Annual Conference of the

Association for Tree-Ring Research

 

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TRACE 2006 - Abstracts


Abstract of Invited Talks
Abstract of Talks
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Invited talks

Dendrochronological proof of origin of historic timber – retrospect and perspectives

Dieter Eckstein

University of Hamburg, Department. of Wood Science, Germany.

Dendro-provenancing has been developing rather unnoticed since about 30 years before it took shape as a sub-field of dendrochronology. The earliest dendrochronological evidence for long-distance timber transport in Central Europe is reported for the early medieval settlement of Dorestad, The Netherlands, the Viking-time trade-place Hedeby/Schleswig-Holstein, and the Slovanic settlement in Wollin/Poland in the estuary of the river Oder. However, these timbers mostly were not intentionally imported but served as containers for the transport of various goods. At their destination, they were re-used as enclosures for wells. The determination of the origin of wood entered the focus of interest only when dendrochronology started to be applied in art-history in the early 1970s. It turned out that the Dutch, Flemish and early German painters up to around 1650 AD painted on oak panels of at least two provenances with completely different tree-ring characteristics. This mystery was disclosed only after nearly two decades when a regional oak chronology had been assembled for the Gdansk area in northern Poland. Meanwhile a pretty dense network of regional and supra-regional chronologies has evolved. But these chronologies were primarily established as a dating tool. However, for dendro-provenancing many of them will have to be dismantled and re-assembled on the basis of specific criteria whose suitability has still to be verified in a joint venture.

The evolution of roofing in Northern France and Belgium from the 11th to the 18th century as revealed by dendrochronology

Partick Hoffsummer

Université de Liège, Laboratoire de dendrochronologie, Allée du 6 Août, 17 (Bât. B5a), 4000 Liège, Belgium.

Thanks to the joint research of the University of Liège (European Center of Archeometry, Laboratory of Dendrochronology), the Center for Research on Historic Buildings (Paris, Ministry of Culture, Media Library of Architecture and Patrimony) and partially based on the work of Henri Deneux, it was possible to publish, in 2002, a synthesis on the evolution of double-sloped roofs in the north of France and Belgium, from the XI to the end of the XVIII century. Using dendrochronological techniques, new material was gathered from almost 100 roofs of the 300 cases considered. The dendrochronological data were analysed by the laboratories of Besancon and Liège, and made it possible to create a chronology for oak spanning the last millennium. All these analyses were integrated into a study focussed on the archaeological context. Certain major monuments, like the cathedrals of Amiens and of Beauvais, or the Hospital of Bijloke in Ghent, were the subject of in-depth studies, using data from 70 to 100 samples per building. At this moment, the work is extended to the study of roofs from the west of France.

 

Abstracts of Talks (alphabetically ordered by first author) (Abstracts of posters see below)

Tree-ring chronology derived from ring widths of the alpine dwarf shrub Empetrum hermaphroditum in the Norwegian mountains

Annette Bär

Department of Geography, University of Bonn, Germany, Department of Biology and Environmental Sciences, University of Oldenburg, Germany

Attempts to derive growth ring chronologies from dwarf shrubs have reveived increasing attention during the last years. Earlier dendroecological analyses of dwarf shrubs were mainly restricted to age determination and descriptions of wood anatomical features. However, efforts to crossdate ring width-patterns failed so far. Thus, successful dwarf shrub growth-environment correlations nowadays avails other parameters than ring width such as annual shoot elongations, flower buds and leaf production.
The crucial point for retrospective growth studies with dwarf shrubs is the correct dating of growth increments to calendar years. Cross-dating has not been successful due to difficulties with (a) the visibility and measurability of annual rings due to their size and distinctiveness, (b) the occurrence of many discontinuous rings due to the asymmetric geometry of dwarf shrub stems, (c) high internal variability within individuals and (d) little knowledge about plant physiology related to annual growth increments in comparison to trees. We overcame these difficulties and succeeded in building an 80 years long chronology of Empetrum hermaphroditum from individuals growing in the middle alpine belt in the continental part of the Norwegian Scandes.
The determination of annual increment areas of each growth ring showed that the asymmetric geometry and occurrence of discontinuous rings within one cross section hardly influenced ring width curve synchronicity. However, synchronization solely based on one single stem section per plant failed due to high internal variability of growth rings within one individual and due to the occurrence of partly missing rings. Thus, three representative plants of each site were analyzed by serial sectioning to derive estimations of internal variability of growth ring formation and to detect partly missing rings. By visual comparison of different stem sections, missing rings could be located exactly in the highly replicated ring width curves. Mean curves of every individual analyzed by serial sectioning served as a reference for other individuals from the same habitat. Nevertheless, some uncertainties about the amount of missing rings in some dwarf shrub individuals remained. These completely missing rings in the Empetrum hermaphroditum samples could be located by the help of a chronology from Betula pubescens growing at the local tree line. Furthermore, first estimations of climate-growth relationships for Empetrum hermaphroditum in the middle alpine belt are presented.

Finding best regression approach for description of climate-growth relation­ships by floating time spans of varying width

Wolfgang Beck

Federal Research Centre for Forestry and Forest Poducts; Institute for Forest Ecology and Forest Inventory, Eberswalde

 Mathematical description of the climate-growth-system (FRITTS, 1976) is a central topic of tree ring research. Especially against the background of changing climate the quantified knowledge about the effects of climatic elements on tree growth is of outstanding importance.
Up to now all approaches use monthly values of climatic variables (temperature, precipitation, combinations of both) or aggregations of these variables within a time span which is thought to be important according to the experience of the author. Any method of data pooling seems to be reasonable at first because climatic data exist at least in daily resolution. Otherwise the flood of data would be unmanageable.
The approach chosen here does not set monthly limits. The only distinction drawn here is between vegetation period (April till October) and dormant period (December till March). Inside these time spans (vegetation period and dormant period) floating time-windows of different width (21 days till 183 days during summer; 21 days till 84 days during winter) are used to aggregate balances of temperature and of precipitation in relation to the averaged values of the period from 1951 to 2003.
All possible variants (about 20 thousands per chronology) according to position and width of the floating time span are tested within multiple regressions by a special computer program. The optimal time span is found if both coefficient of determination and coefficient of “Gleichläufigkeit” between time series of tree ring index and time series of modelled values of tree ring index arrived maximum. Simultaneously the size of sensitivity of the original time series should nearly be arrived by the modelled time series.
In this way the most important time spans related to tree growth inside of the year are found and summarized to a full regression model. After this, model-reduction is carried out by backward selection strategy (t-test).
The result of the whole procedure consist of reliable mathematical descriptions of how climate acts on tree growth. The regression models express the majority of variance (66% to 90%) and reflect the properties of original index series by high degrees of “Gleichläufigkeit” and sensitivity of the modelled series.
By using this method it seems to be feasible to acquire the knowledge base which is necessary as decision support for future forest tree species choice by silviculture.

Answer to the climatic signal in the dependence on site type in spruce stands of Borecka Primeval Forests

Szymon Bijak

Department of Dendrometry and Forest Productivity, Faculty of Forestry, Warsaw University of Agriculture

The aim of the study was to determine the reaction of spruce trees for climate conditions depending on the different habitat type.
Increment cores were taken from three, spruce-dominated stands located in Borecka Primeval Forests, which is considered as one of the least polluted areas in Poland. The stands represent a mixed-deciduous forest habitat type and differ with moisture level.
Tree-ring chronologies ranging from 1846 to 2005 were built for each moisture class and for the whole area separately using available computer programs (ARSTAN, ZGODA, DENDRO). Relationships between meteorological conditions and width of the annual increment ring were examined for temperature, precipitation and synthetic indices describing thermal and pluvial conditions. Analysis was based on the ‘response function’ procedure (program RESPO) and on pointer years which were determined with ‘normalisation in a moving window’ method.

Dendroarchaeology in the Federsee-basin (southern Germany)

Niels Bleicher

Römisch-Germanisches Zentralmuseum Mainz, Ernst-Ludwig-Platz 2, D–55116 Mainz, Germany

In the Federsee-basin near Ulm in southern Germany several settlements from the late neolithic (ca. 3300 – 2900 BC) have been found in a peat-bog. Due to the lack of oxygen in the peat organic matter and especially wood has been preserved. The wooden remains of the architecture have been investigated dendrochronologically. In this presentation some aspects and examples of the current analyses will be given as well as their implications for archaeological studies.
Archaeological wood does not only provide us with an absolute timescale but has the potential to give information on settlement-dynamics, stone-age economy and ecology. The analysis of the settlement-dynamics can give better estimates of settlement-density, because it is often impossible to tell by archaeological means alone whether two settlements are synchronous, but there are also further indications on social organisation that can be inferred from tree-ring data. The underlying question in terms of economy and ecology is how the use of wood was organized: which aspects of the economical activities made use of wood, how were they organized and how did this influence the local ecology? Did shortages in wood-supply already exist in the stone-age?
The material to answer these questions consisted nearly completely of stems with a diameter between 5 and 15 cm. Few material was larger due to human activities and selection for technical purposes. The species that were used for the houses and trackways were mainly Ash (Fraxinus exc.), Beech (Fagus sylvatica), Alder (Alnus spec.), and several other less important deciduous species. Thus the measurements were extremely difficult due to missing rings, short sequences and very heterogeneous curves because of the distorting effects applying to understory-growth. Furthermore the preservation was sometimes a problem. Great care had to be taken in the building of the chronologies. Since the reference-chronologies consisted of oak and material that has been collected about 100km further to the south some of the dating had to be accomplished by wiggle-matching.
To overcome all these difficulties a thorough dendrotypological analysis was applied and using archaeological data as indicators for relative dating it was even possible to achieve the heteroconnection, which means to cross-date mean-curves of different species.
It can be shown that there existed different concepts of the use of forests. These differences comprise the used species, their age and shape at the time of felling and the rhythms of felling-activity. Corresponding to this there also existed different settlement-types and planning-depths. Within a small regional frame the archaeodendrological analysis revealed different economical strategies. It was also possible to investigate a complex stratigraphy at Alleshausen-Grundwiesen. The rhythms and organisation of forest-use were not only locally but also regionally different. This leads to the question how the local ecology and climate influenced cultural behaviour.

Dendro-ecological reconstruction of a Late-Glacial pine forest in Reichwalde, E-Germany.

Ilse Boeren, Hans-Peter Stika, Maria Knipping, Michael Friedrich, Manfred Küppers

Inst. für Botanik (210), Universität Hohenheim, 70593 Stuttgart.

A vast and well preserved Late-Glacial pine-birch forest has been excavated in a lignite mine in Reichwalde. The advantageous circumstances for the preservation of organic material (inundation and peat-formation) provided more than 1500 subfossil trees “in situ”. They cover a period of about 800 years in the Bølling-Allerød Interstadial (14100–13300 yrs BP). Additionally, information about Late-Glacial vegetation development is given by peat sediments, prior and subsequent to the preserved forest. The dendrochronological dating of stratified pines makes it possible to precisely date the sediment, to directly connect the trees with the bog stratigraphy and thus to compare the results of the dendro-ecological investigations to the pollen and botanical macro-remains analysis. In this way, bio- and chronostratigraphy can be connected.
The fact that most of the trees were found “in situ”, allowed us to reconstruct the stand structure of great parts of the forest, over the different generation phases. This revealed that most stands have had a rather open structure and that the populations existed out of trees of different age.
There is a great difference between the tree-ring parameters in the older part (first 350 yrs) and those in the younger part (last 450 yrs) of the chronology. In the first part the rings are wider and the trees died younger than in the second part. The tree-ring series are more sensitive, but there are less pointer years in the chronology. The Mean Fire Return Interval is about ten times shorter and much more charred botanical material is found in sediments from this time. All these features indicate that in the earlier Allerød, the trees were more influenced by environmental factors than by climate and that in the later Allerød, the climate must have become more interfering with tree growth. This can also be confirmed by the better correlation of the Reichwalde chronology with the northern and southern Germany chronologies in the younger 400 years. This switch in character of the series coincides with a presumptive large-scale water-level increase, which made it impossible for trees to grow on the greater part of the bog. The only trees which are younger than that event have been standing on a small higher-scale part in the north. Pollen and macro-remains confirm a change in hydrology at that time.
Using precisely dated fire scars on the trees, we composed an 800 year fire chronology. This chronology, as well as the age structure of the forest, suggest that fires were a dominant ecological factor in the forest. The severity of the fires has probably not been strong, since most of the trees have survived many fires; the frequency, on the contrary, was very high. This could be confirmed by the results of the palaeobotanic investigations: bushes were rarely found, the undergrowth was dominated by sedges, grasses and other grass-like vegetation.

Calibration of Radiocarbon dates

Mathieu Boudin, Mark Van Strydonck

Royal Institute for Cultural Heritage, Brussels, Belgium.

Calibration of a radiocarbon date is necessary to link the radiocarbon time scale to the calendar time scale. Calibration curves are available in the time range 0 - 26,000 BP. The younger part of this curve (0-12.4 cal ka BP) is established by radiocarbon dating of dendrochronologically established master curves. Tests have shown that there is a small offset between the Northern and Southern hemisphere. Changes in the production rate of atmospheric 14C results in periods of higher and lower precision (wiggles).
Radiocarbon can be a tool in dendrochronological studies: (1)An absolute age can be given to a floating tree ring curve, (2)Wiggle matching can give much more precise dates, (3) Calibration of post-bomb 14C samples can provide calendar dates of post 1950 trees dated by radiocarbon.
The most common tools available to the user are the OXCAL program and the CALIBOMB program available on the internet. Also other programs are available (CALIB, BCAL, CALPAL, WINCAL) on the internet. However, one has to be very alert in using the CALIBOMB program because of an error in the program.

Tree growth and climate in the Tatra Mountains

Ulf Büntgen (1), David Frank (1), Ryszrad J. Kaczka (2), Anne Verstege (1), Tomasz Zwijacz-Kozica (3) and Jan Esper (1)

(1) Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
(2) Faculty of Earth Science, University of Silesia, 60 Bedzinska 50, 41-200 Sosnowiec, Poland
(3) Tatra National Park, Chalubinskiego42a, 34-500 Zakopane, Poland

We aggregate 24 tree-ring width and 4 maximum latewood density chronologies from the greater Tatra region (Poland/Slovakia). The network comprises 1,183 tree-ring width and 153 density measurement series, and considers four conifer species (Picea Abies, Larix decidua, Abies alba, and Pinus mugo) from elevations between 800-1,550 m asl. Individual spline detrending is used to retain annual to multi-decadal scale information from the data. 20th century temperature and precipitation data from 16 grid-boxes covering the 48-50°N and 18-19°E region are utilized for comparison. The network is analyzed to assess growth/climate response as a function of species, elevation, parameter, frequency, and site-ecology. Twenty ring width chronologies correlate significantly with June-July temperatures, while the density chronologies reveal strongest response to the wider April-September season. Increasing precipitation response with decreasing elevation is observed. Climatic effects of the previous year are generally insignificant, while site elevation and frequency are evident. Correlations between summer temperatures and the annual growth rates of Larix decidua are lower than for Picea abies, although cyclic defoliation patterns of larch budmoth outbreaks are not distinguished. Principal component analysis elucidates five dominant eigenvectors from the network. The first principle component contains highest loadings from 12 Picea abies ring width chronologies and explains 42% of the network’s variance. The mean of these chronologies correlates at 0.62 (p<0.001) with June-July temperatures, while the mean of the three density chronologies that load most strongly on the second principle component, correlates at 0.69 with April-September temperatures (1901-2002). These mean chronologies allow for the robust estimation of June-July (1661-2004) and April-September (1709-2004) temperatures, respectively. Regional- to continental-scale network analyses from the Alps and Central Europe support the dominant role of homogeneous warm season temperatures on high-elevation tree-growth. Our findings are valid for any revised climatic reconstruction, and long-term estimation of forest net primary productivity in the greater Tatra region.

Threshold of land-use abandonment controls the rate of tree regeneration and forest dynamics in a Mediterranean mountain ( Provence, France)

Sandrine Chauchard (1,2), Christopher Carcaillet (1), Frédéric Guibal (2)

(1) Centre de Bio-Archéologie et d’Ecologie (UMR 5059 CNRS), Institut de Botanique, 163 rue Broussonet, 34090 Montpellier, FRANCE
(2) Institut Méditerranéen d’Ecologie et de Paléoécologie (UMR 6116 CNRS), Bâtiment Villemin, Domaine du Petit Arbois, Avenue Philibert, BP 80, 13545 Aix en Provence, FRANCE

Mediterranean ecosystems are impacted for millenniums by human practices such as permanent agricultural and pastoral activities. Since the end of the 19 th century, the traditional land-use abandonment has lead to shrubland and forest expansion, especially in mountain areas. Here, we analyze a mountain forest dynamics by dendrochronology. The approach includes analysis of land-use from archival documents crossed with tree-ring analysis to investigate the origin, establishment and development of forest following the chronology of land-use abandonment. Forest structure and dynamics are investigated with respect to the local agricultural history and former land-uses. Tree colonization started in the 1890s with Scots pine (Pinus sylvestris) regenerating quickly after abandonment. The net rate of recruitment increased during the 1930s when pasture by sheep kept dropping. Beech (Fagus sylvatica) and fir (Abies alba) have been regenerating in the understorey of pines since the 1960s. Regeneration appears controlled by a threshold of grazing pressure. However the timing of forest colonization differs according to the former type of land-use: colonization began in pastures then in ploughed areas. In a Mediterranean mountain ecosystem, agricultural history and the rhythm of land-use abandonment are a significant driving force explaining forest dynamics. Knowledge of the agricultural history and former land-use is critical to understand and predict forest dynamics in the Mediterranean mountain.

Nature and periodicity of growth rings in Sonneratia apetala Buch.-Ham., a Bangladesh mangrove species

Qumruzzaman Chowdhury (1), Nele Schmitz (2,3), Anouk Verheyden (3), Ute Sass-Klaassen, Nico Koedam (2) & Hans Beeckman (3)

(1) Forest Ecology and Forest Management group, Center for Ecosystem Studies, Wageningen University, P.O box 47, 6700 AA Wageningen, The Netherlands.
(2) Laboratory for General Botany and Nature Management (APNA), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium.
(3) Royal Museum for Central Africa (RMCA), Laboratory for Wood Biology and Xylarium, Leuvensesteenweg 13, 3080, Tervuren, Belgium.

Mangroves occur along the coast of (sub)tropical areas and play an important economical as well as ecological role (Rönnbäck 1999; Dahdouh-Guebas et al. 2005; Walters 2005). In Bangladesh Sonneratia apetala is the main species used for coastal afforestation purposes (Hoque and Datta 2005) and has proven its value as a barrier against extreme flood events (Blasco et al. 1992).
Because of the absence of a clear dormancy of the cambial activity, many tropical trees fail to produce distinct growth rings which prevent dendrochronological applications (Sass et al., 1995). Nevertheless, Sonneratia has been mentioned to show distinct growth rings bordered by a layer of flattened fibres (Panshin 1932; Rao et al. 1987). However, their periodicity has never been analysed before. In this study the dendrochronological potential of S. apetala’s growth rings is investigated. Knowledge about the periodicity of the growth rings will possibly enable age and growth-rate determinations, important to improve the efficiency of mangrove management programmes. In addition, an analysis of the ring periodicity could make it possible to trace environmental changes that cause mangrove decline worldwide (Spalding et al. 1997; Kovacs et al. 2001).
In this study the nature and periodicity of S. apetala’s growth rings is investigated. On three stem disks of a plantation of known age rings were counted and ring width measured using digital image analysis software (Analysis 3.0). In addition, high resolution measurements were carried out of several wood anatomical characters (vessel density, vessel grouping, tangential and radial vessel diameter) in transects from pith to bark to trace possible periodic signals (Verheyden et al. 2004; Verheyden et al. 2005).
Ring counts corresponded with plantation age and ring width chronologies were crossdatable. In contrast, no clear periodicity was found in the time series of the vessel characters. It is concluded that the growth rings in S. apetala from Bangladesh are delimited by a band of flattened fibres and show an overall annual nature. This finding reveals the suitability of S. apetala for further dendrochronological investigations.

The origin of large oak clusters in the Netherlands

Paul Copini, Ute Sass-Klaassen & Jan den Ouden

University of Wageningen, Forest Ecology and Forest Management, PO Box 47, 6700 AA, Wageningen, The Netherlands

In the Netherlands large oak clusters (Quercus robur L. & Q. petraea (matt.)Liebl.) with sizes up to 33 meters in circumference were discovered in 2001. Genetic research of oak clusters in a drift sand area as well as in an area with preglacial material showed that these large clusters can be genetically identical, but can also contain a mixture of genotypes. Still there is the question how these oak clusters originated?
We used amongst others a dendrochronological approach to study growth pattern and age of stems belonging to oak clusters with a known history (e.g. coppice stools, grazed oaks shrubs) in order to find characteristics, which could be used to test hypothesis about the origin of these large oak clusters with unknown history.

Influence of climatic factors on the radial growth of Pinus sylvestris in different regions and habitat types in Latvia

Didzis Elferts

University of Latvia , Faculty of Biology, Kronvalda bulv. 4, Riga, Latvia, LV-1586

Scots pines (Pinus sylvestris) in Latvia grow in different habitat types, for example, on dunes, in bogs, on sandy soils. The climatic conditions across Latvia also differ, and there are some regional changes that could have an effect on the growth of pines. The aim of this study is to determine the main climatic conditions affecting the growth of Scots pine (Pinus sylvestris) in Latvia and if there are differences across regions and habitat types.
Samples of tree-rings from pines were taken in different regions (sites) of Latvia using coring (one sample per tree) or taking stem disks (measured at three diameters). The habitat types were bogs, bog islands, dunes, forests on sandy soils. Tree-ring series were dated, then residual chronologies were built for every site, and also one common chronology including trees from all sampling-sites. Correlation and multiple regression analyses were used to determine the relationships between climatic factors (temperature and precipitation) and tree growth. Information on temperatures and precipitation were available starting from 1850 for the Riga region and from 1924 for other regions.
The response to climatic conditions differed among habitat types and regions in Latvia but there were cases when trees across Latvia responded similar to some climatic factors, especially in years with extreme climatic changes, for example, years with lower temperature compared to average temperature.
This study was financially supported by European Social Fund.

On chronology development and changes in sample replication.

David Frank, Jan Esper

Swiss Federal Research Institute WSL, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland

 It is a common property of environmental time-series data that the number of observations does not remain constant over time. This consideration is inherent to dendrochronology whereby a chronology composed of living trees typically contains the greatest numbers of samples in recent years, with replication declining in earlier decades and centuries. Similar considerations apply to chronologies that combine relict/historical/sub-fossil material, networks of chronologies, and instrumental data. Varying sample replication results in quality changes in the mean-value estimate as well as changes in its local variance. In the case of the variance, if left uncorrected, the mean value function and any subsequent analyses will be systematically biased solely due to sample replication changes. In this talk, dendroclimatic results ranging from single site chronologies to a Hemispheric-scale temperature reconstruction will be presented that show how replication changes may manifest themselves in the mean time-series and also be considered/corrected.

Dendroclimatology in the Low Mountain Ranges, Germany

 Dagmar Friedrichs, B. Neuwirth & J. Löffler

Department of Geography, University of Bonn, Meckenheimer Allee 166, 53115 Bonn, Germany

The world-wide precipitation amount increased at about 2% within the 20 th century due to a changing atmospheric circulation. The spatial and temporal variability of this increase is not completely understood. Hence, for a profound assessment of the impact of global change on the regional scale further spatial high resolved analyses are indispensable. These analyses can only benchmark the current precipitation patterns by using long-term reconstructions. These reconstructions should place recent changes in context of the previous environmental situation. Although earlier studies indicate that precipitation is a dominant growth-limiting factor at specific sites, only few attempts have been made in Central Europe to reconstruct precipitation from tree rings. Initial dendroecological investigations in the Rheinische Schiefer­­­­­gebirge confirm the strong influence of precipitation on growing-patterns of oaks and demonstrate that tree-ring/climate-relationships are not constant over time. In this study long and annually resolved tree-ring records will be used to estimate changes in precipitation variability over, at least, the last three centuries for the northern low mountain ranges in Germany and parts of some neighbouring countries. By combining recent and historical ring-width series, we intend to analyse the signals of both, temperature and precipitation on tree-ring growth in order to reconstruct precipitation patterns. A new methodological approach will be established, whereby we will consider the spatial and temporal variability of relationships between tree rings and climate. This approach combines dendroecological methods and multivariate statistics such as cluster analysis and GIS techniques. To include the spatial variability of precipitation patterns in the dataset a spatially high-resolved network of sites will be arranged for the entire study area. The reconstructions will present precipitation variability on different temporal scales, from interannual to multi-decadal.

Wood formation in locally heated and cooled stem of Norway spruce (Picea abies)

Jožica Gričar, Katarina Čufar, Primož Oven

University of Ljubljana, Biotechnical Faculty, Department of Wood Science and Technology, Rožna dolina, Cesta VIII/34, SI-1000 Ljubljana, Slovenia

Experiments performed in controlled conditions are useful to better understand the influence of individual climatic factors on wood formation. The purpose of this study was to investigate the response of the cambium of Norway spruce (Picea abies) to experimental heating (23-25°C) and cooling (9-11°C) in the growth period 2005. For the experiment, three 70-year old Norway spruce test trees were selected in an urban Norway spruce/beech forest Rožnik in Ljubljana, Slovenia. One adult tree was used for the heating and one for the cooling experiment. The third Norway spruce was non-treated and served as a control. Small blocks of samples (1 x 1 x 3 cm 3) containing inner phloem, cambium and outer xylem were taken from trees at 20-day intervals (from 24 th April until 4 th November, 2005). Samples were fixed in FAA, dehydrated and embedded in paraffin. Transverse sections (13 µm in thickness) were prepared on a rotary microtome, stained with safranin an astra blue, and observed under light microscope. Cooling part of the stem of Norway spruce tree shortened regular cambial activity (approximately for 3 weeks). Constant low temperatures reduced xylem increment for one third comparing to the control tree. In addition, the rate of cell production on the xylem side was slowed down during the entire growth period. Very narrow xylem growth ring of cooled Norway spruce reflected typical structure of the trees growing in unfavourable conditions. Warming part of the stem of the Norway spruce didn’t cause drastic alterations in regular cambial activity or cell differentiation during the growth period. The heat treatment didn’t extend cambial activity at the end of the growing season, as previously expected. Divisions in the cambium stopped in the first half of August, similar as in the control tree. Xylem increment was slightly wider compared to that in the control tree probably due to higher rate of cell production in the cambium, especially at the beginning of the vegetation period. Our experiments demonstrated that heating and cooling influenced cambial activity in Norway spruce and confirmed the importance of external factors (in addition to internal factors) on cambial activity and corresponding cell differentiation.

Combining different tree-ring parameters for a multi-proxy approach: an example from the Tibetan plateau

Jussi Grießinger (1,2), Achim Bräuning (2) & Gerhard H. Schleser (1)

(1) Forschungszentrum Jülich, Institute für Chemie und Dynamik der Geosphäre ICG-V, Abt. Isotopengeochemie und Paläoklima, D-52425 Jülich
(2) Universität Stuttgart, Institut für Geographie, Azenbergstr. 12, D-70174 Stuttgart.

Analysing climate and environmental information from tree ring data is a common tool for reconstructing past environments. Most of these reconstructions are mainly based upon one single parameter like ring width or maximum latewood density. In recent publications, McCarrol et al (2003) and Gagen et al (2004) demonstrated the high potential of combining different tree-ring proxies for dendroclimatological investigations.
The location of our sampling site is close to the upper treeline near the city of Qamdo in south-eastern Tibet. The location is representative for the regional climate of the eastern part of the Tibetan plateau. The trees at the study site are very sensitive to climate variations and therefore very suitable for a detailed proxy-climate investigation. The region is characterized by a seasonal change of two major atmospheric circulation systems. During summer, humid air masses of the Indian summer monsoon and the East Asian monsoon are the prevailing factors of regional climate. In winter, cold westerly winds with small amounts of precipitation are dominating.
The aim of our study is to analyse the potential of combining different tree-ring parameters like ring width, maximum latewood density data and stable carbon and oxygen isotope series for a comprehensive climate reconstruction. To study tree-species specific reactions to climate forcing we use two different tree species. We selected junipers (Juniperus tibetica) from a southern slope and spruce (Picea balfouriana) from a northern slope. Both species provide continuous, annually resolved records covering a period of approximately the last 400 years for all investigated proxies.

McCarroll, D., R. Jalkanen, S. Hicks, M. Tuovinen, M. Gagen, F. Pawellek, D. Eckstein, U. Schmitt, J. Autio & O. Heikkinen (2003): Multiproxy dendroclimatology: A pilot study in northern Finland. In: The Holocene 13(6):831-841.
Gagen, M., D. McCarroll & J.-L. Edouard (2004): Latewood width, maximum density and stable carbon isotope ratios of pine as indicators in a dry, subalpine environment. In: Arctic, Antarctic and Alpine Research 36(2):166-171

Wood anatomy and Dendrogeomorphology - Reaction wood varieties caused by different experimental treatments

 Ingo Heinrich (1), H. Gärtner(2) & M. Monbaron(1)

(1)Department of Geosciences, Geography, University of Fribourg, 1700 Fribourg, Switzerland
(2)Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland

Geomorphic events such as debris flows usually have a significant impact on tree growth resulting in conspicuous changes of ring-widths and wood densities. To date, several dendroecological techniques have been developed for the successful determination of frequencies of these events. However, it has only rarely been accomplished to retrieve more information from the reaction wood, e.g., type and intensity of the geomorphic event. Additional qualitative information retrieved from the reaction wood of trees hold the potential to not just date but reconstruct important characteristics of natural hazard events. The ability to date mass movement events intra-seasonally and also to retrieve more qualitative details would be particularly helpful in study regions without detailed knowledge of the predominant geomorphic process. Long-term reconstructions of geomorphic events would also benefit because it is likely that the tree-ring signals for different mass movements such as debris flows and avalanches can not be separated when occurring at the same site and consequently are all mixed into one reconstruction not distinguishing between the different processes. Consequently, comprehensive wood anatomical analyses of reaction wood induced artificially as part of a growth experiment have the potential to obtain more complete information on the potentially different tree reactions to these dissimilar events. To refine the methods already used in dendrogeomorpology long-term growth experiments imitating typical impacts of different geomorphic events were set up. During the experiments the wood anatomical reactions of four common European tree species (Picea abies, Larix decidua, Fagus sylvatica and Alnus glutinosa) were monitored over a period of 18 months. The results demonstrate that the tree species show distinct variations in their reactions due to the various experimental treatments differing in intensity and intra-seasonal timing. This new interdisciplinary approach has advanced commonly used techniques in dendrogeomorphology which will help to extract more detailed qualitative and quantitative information stored in trees and to improve the knowledge of natural hazard processes in future applications.

Intra-seasonal oxygen stable isotope signals in the arboreal system – A case study with Pinus strobus and Fagus sylvatica

Gerd Helle (1), T.J. Drees (2), P. Strauch (2) & G.H. Schleser (1)

(1) Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre, ICG-V: Sedimentäre Systeme, 52425 Jülich, Deutschland
(2) Westfälische Wilhelms-Universität, Institut für Ökologie der Pflanzen, Hindenburgplatz 55, 48143 Münster, Deutschland

Dendrochronology has in the past provided most valuable information (wood anatomy, ring density, ring width, and wood isotopes) on environmental change at annual/seasonal resolution. However, tree rings do not directly record changes in their vicinity. Therefore, it is very difficult to deduce quantitative information on annual or seasonal scale, because the applied (statistical) methods, based on our current understanding of tree-ring formation are rather limited. A better understanding of the processes governing tree-ring response to environmental forcing is needed for understanding the causes and limits on past and future tree growth. In this respect, high resolution intra-annual isotope studies of the arboreal system can help to elucidate the seasonal signal transfer in trees and their response to environmental changes.
It has to be considered, that intra-seasonal changes of ambient environmental conditions are recorded within a tree-ring by the specific way continuous accumulation of wood cells develops during the growing season. Furthermore, climatic factors govern isotopic effects, mainly at the site of photosynthesis, i.e. leaf level, and subsequent fractionations re­lated to plant physiological processes alter further the isotope signals stored in the tree-rings.
The poster will focus on results from the ongoing ecophysiological process studies on isotope signal transfer in trees from a forest lysimeter facility in St. Arnold in NW-Germany. Up to now over 40 years of tree-growth measurements, meteorological variables and local water cycling data are at hand. Results on intra-seasonal oxygen stable isotope variations in relation to carbon isotope and wood density analyses on Pinus strobus and Fagus sylvatica trees will be presented.

Interactions between archaeology, trees and climate in northern England.

Jacqui Huntley

English Heritage and Department of Archaeology, Durham University.

Sea defense management at Staithes in North Yorkshire, UK uncovered timbers and associated roundwood considered to be man-made. Archaeological investigation was undertaken. The large timbers were radiocarbon dated to the Bronze Age, ca 3300 years ago and their ring sequences produced a good internal cross-match. These, however, could not be matched to any master chronology, despite knowing their radiocarbon age. This paper produces some research undertaken to investigate this, looking at the two species of British oak, Quercus robur and Q. petraea and their responses to warmth and moisture. Preliminary results suggest that there are significant differences in these responses meaning that any technique to characterise archaeological wood towards one or other of these two species could be crucial.

The dendrochronological records of debris flow activity in SE Quebec

Ryszard J. Kaczka, Hubert Morin

Laboratoire d'Écologie Végétale, Université du Québec à Chicoutimi, Quebec, Canada

The debris flow, rapid mass movement of water-saturated sediments, is one of the main processes modeling the high mountainous slopes. However this phenomenon can occur on each steep hill covered by unconsolidated sediments. The postglacial relief of the south-east Quebec, rich of steep-slope fjord type valleys, is conducive to study the debris flows activity in non-mountainous environment. The area of investigation covered by boreal forest consists of coniferous species as balsam fir ( Abies balsamea ), white spruce ( Picea glauca ) black spruce ( Picea mariana ). The aim of the study was to assess the spatial and temporal dynamics of that particular kind of mass movement. The stages of debris flows activity and the post-event evolution of the debris flow were reconstructed. The scars, inter-trunk wood anomalies (reaction wood, resin ducts) and tree ring patterns (growth reduction) were use as sources of information about the debris flows activity. They record both the date and intensity of the mass movement with annual precision. The existence of the model of inter-annual ring development of balsam fir in boreal forest, gives the opportunity of even more accurate dating. The study of the phase of development of exposed part of the ring reflects the period of the growing season when injures of trees and damages of the cambium occurred. The research was conducted in three valleys in north of the Saguenay River . Twelve cases of two types of debris flows were studied. The geomorphologic characteristic of slopes and the debris flows were established by field examination and analysis of the maps and satellite images. The disc samples (approximately 20 per site) were taken from the trees growing on the edge and fan of debris flows. The comparison of existing records of daily precipitation and obtained dates of debris flows events shows that even daily rainfall, which reached 40 mm could trigger the failure. The last and also very intense period of debris flows activity occurred in 1996, and was related to extremely high precipitation (almost 100mm on July 19 th and 50mm on September 14 th). All 12 examinated debris flows were active in 1996 and for some of them evidences of previous movement were not found. Erosion of all uncovered parts of the debris flows (levee, lob and fan) has remained the main post-event morphological process after 10 years of the events. Most of the dated events occurred in the second part of the 20 th century. The dynamic of boreal balsam fir forest is the main limiting factor of the dating of older events (the average age of sampled tees did not reach 100 years).

Response kinetics of tree radial growth to environmental perturbations - A challenge to the equilibrium hypothesis

Hans-Peter Kahle

Institute for Forest Growth, University Freiburg, Germany,

Tree radial growth varies on different time scales. In chronology building the concept of standardization builds on the hypothesis of equilibrium growth. Elasticity is an important component of equilibrium conditions. Systems that maintain their properties despite disturbance and that return rapidly to their original state exhibit more stable properties. However, depending on the nature, magnitude, and duration of the perturbation and on the nature of the system itself it may never recover to its original state but will be converted to a new state. Hence, the stability of an ecological system to environmental perturbations can be assessed by means of its elasticity.
This research into the growth response kinetics of Norway spruce (Picea abies L. Karst.), silver fir (Abies alba Mill.) and common beech (Fagus sylvatica L.) trees is based on observational growth data from southern Germany. Long-term tree-ring time series from selected sites were retrospectively analyzed using superposed epoch analysis. Response surfaces were parameterized to model growth elasticity.
The rate of radial growth elasticity depends on the magnitude of the initial growth deflection, it differs between tree species and depends on tree age as well as on the site conditions. Furthermore it is shown, that radial growth elasticity is not constant over time.

Dendroglaciological reconstruction of late-Holocene glacier activity in the southern Boundary Range, British Columbia Coast Mountains, Canada .

Sarah Laxton (1), S. Jackson (2) and D.J. Smith (2)

(1) Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221-0013, U.S.A.
(2) University of Victoria Tree-Ring Laboratory, Department of Geography, University of Victoria, Victoria, British Columbia V8W 3P5, Canada.

Accelerated glacial recession and downwasting in Pacific North America is exposing land surfaces and features buried by glacial advances that, in many locations, predate the recent Little Ice Age. Dendrochronologic analyses of increment core samples from living trees (Abies lasiocarpa,Tsuga mertensiana) and samples of subfossil wood collected in the Todd Icefield area, Boundary Ranges, British Columbia Coast Mountains, provide the basis for a dendroglaciological reconstruction of late-Holocene glacier activity. Radiocarbon analyses and tree-ring crossdating resulted in the identification of several phases of late-Holocene glacier activity including the: Sage Advance (BC 420-200); the Bridge Advance (AD 405-640); and, four intervals of Little Ice Age glacier fluctuation (AD 1200-1390; 1250-1420; 1400-1630; 1640-1950). Our findings confirm the timing of late-Holocene glacier activity emerging from other regions in the British Columbia Coast Mountains. In addition, they provide the basis for developing an annually resolved tree-ring and glacial advance chronology that potentially spans the last three millennia.

Long-term trends in growth of Siberian spruce and Scots pine in Komi Republic, Russia

Eugene Lopatin (1,2), Taneli Kolström (2), Heinrich Spiecker (3), Hans-Peter Kahle(3)

(1) Institute of Biology, Komi Science Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
(2) University of Joensuu, Mekrijärvi Research Station, Joensuu, Finland,
(3) Albert-Ludwigs-University Freiburg, Institute for Forest Growth , Freiburg, Germany

To adopt forest management practices to changing environment, it is important to understand the response of unmanaged natural forests to changing climate. Komi Republic is the region of Northwestern Russia where large areas of natural boreal forest still exist. Analysis of climate data for the last century showed that significant long-term trends in climate can be identified in this region. During the last 20 years air temperature increased at most of the meteorological stations compared to the preceding 40 years period and precipitation began to increase too. Length of thermal growing season substantially extended in the region.
In order to retrospectively analyze tree growth along a latitudinal transect across the region stem discs or increment cores from sample trees were collected in six stands in four forest zones of Komi Republic: south taiga sub zone of boreal forests, middle taiga sub zone of boreal forests, northern taiga sub zone of boreal forests, and forest-tundra transition zone. Mature dominant trees without visible signs of damage were randomly selected as sample trees (n=92 trees of Siberian spruce and n=90 trees of Scotch pine).
Significant long-term trends of increasing site productivity were detected. Increase in mean apical growth of Siberian spruce in the forest-tundra transition zone for the last 50 years was 29.8% compared to the long-term mean level of growth of the previous 50 years. The respective figures for the other zones are: northern taiga zone 25.0%; middle taiga zone 19.1%, and southern taiga zone 0.4%. Increase in apical growth of Scotch pine in the northern taiga zone was 6.8%; in middle taiga zone 37.9%; in southern taiga zone 88.3%.

Dendrochronological records of erosion and accumulation in mid-mountain stream ( Jeseniki Mountains – Czech Republic)

Ireneusz Malik, Piotr Owczarek

University of Silesia, Faculty of Earth Sciences, Bedzinska 60, 41-200 Sosnowiec, Poland

Date of exposure of spruce roots as result of bank erosion and tree rings reduction as result of mechanical stress was investigated on the Cerny Potok in the north-eastern Czech Republic. Following the exposure of roots, wood cells in the tree rings divide into early wood and late wood. Root cells within the tree rings also become smaller and more numerous. These processes permit the erosion episodes in which roots were exposed to be dated. Material is transported downstream and wounding spruces growing in the bottom of the valley as result of this process tree rings reduction occur. Forty root samples and thirty five cores from trees were taken from seven sampling sites. The results of root exposure dating and trees wounding were compared to historical data on hydrological flooding. Using the root exposure tree ring reduction dating method, several erosion episodes were recorded in the last 100 years.
The greatest bank erosion was recorded in July 1997 during an extraordinary flood, but several another erosion and accumulation episodes were recorded. A lot of signals were recorded in 1953, 1968, 1983 and 1986. Signals recorded by exposed roots analyse very often are not synchronic with signals recorded by tree rings reduction. Material is delivered into the river channel not only as results of bank erosion. Numerous debris flow events in the upper part of the studied valley supply material to the riverbed.

Influence of urban environment on cambial growth in Aesculus hippocastanum L. and Acer platanoides L.

 Lena Marion (1,2), Jožica Gričar (1), Primož Oven (1)

(1) University of Ljubljana, Biotechnical Faculty, Department of Wood Science and Technology, Rožna dolina, Cesta VIII/34, 1000 Ljubljana, Slovenia
(2) Tisa d.o.o., Ižanska cesta 213, 1000 Ljubljana, Slovenia

 Trees in urban area are mostly growing in much harder conditions compared to their natural environment. The aim of the study was to asses the influence of common urban growing conditions on cambial activity and wood formation in horse chestnut (Aesculus hippocastanum L.) and Norway maple (Acer platanoides L.) in the City of Ljubljana, Slovenia.
Two groups of each species were selected: a control group of six unaffected trees and a group of six heavily affected trees due to poor, compacted and with de-icing salts polluted soil, lack of root space and mechanical wounding by excessive pruning. Micro-cores (diameter 1.8 mm) were taken from trees at the breast height with Trephor instrument. Sampling was performed at weekly intervals during the growing season 2005. Tissues were fixed in FAA and embedded in paraffin. Cross-sections were prepared with a rotary microtome, stained with safranin and astra blue and mounted in Euparal for light microscopy.
Our results confirmed great effect of harsh conditions on tree growth. Unaffected trees had considerably bigger diameter at breast height and bigger crown diameter compared to the affected ones. In addition, differences in wood anatomy were noticed. The more the trees were affected, the narrower were their xylem growth rings with less distinctive growth ring boundaries. Narrow xylem growth rings in Norway maple had more distinctive growth ring boundaries comparing to horse chestnut.
Compared to affected trees, the average period of cambial activity and wood formation in unaffected trees was 4 and 6 weeks longer for horse chestnut and Norway maple, respectively. Higher variability (more than one month) in period of cambial activity and wood formation was detected among affected trees.
Influences of pollution with de-icing salts, water stress, soil compaction and area with limited space for normal root development lead to suppressed radial growth, poorly developed crowns with dying branches and finally higher mortality of trees. Our results show urgent need for city tree management action to prevent further dieback of trees.

Dendrogeomorphological analysis of alpine trees and shrubs growing on active and inactive rockglaciers  

Isabelle Roer (1,2), Holger Gärtner (1) & Ingo Heinrich (3)

(1) Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
(2) Department of Geography, University of Bonn, Meckenheimer Allee 166, 53115 Bonn, Germany
(3) Department of Geosciences, Geography, University of Fribourg, Pérolles, 1700 Fribourg, Switzerland

The occurrence of permafrost and related landforms (rockglaciers) is a widespread phenomenon in many high mountain geosystems. Diverse methods like geomorphic mapping, geodetic survey as well as photogrammetric analyses were applied for the determination of permafrost distribution and rockglacier kinematics in order to understand the geosystems’ sensitivity to climatic changes. In this study we present the first-time application of dendrogeomorphological methods in this context.
To determine the impact of permanently frozen ground and the influence of ground movements (by permafrost creep) on plants, wood-samples were taken from active and inactive rockglaciers in the Turtmann Valley, southern Swiss Alps. Due to their typical position above timberline, the occurrence of trees is limited. Therefore, the investigation was restricted to single trees (Pinus cembra) and several shrubs (mainly Salix helvetica). The plants sampled cover a period of 30 to 40 years. Working with dwarf shrubs, the extraction of cores is in most cases not possible. Thus, the whole plant was cropped and samples were taken from roots and stems. Besides the analysis of ring-width variations, the analysis focused on the anatomical structure of the rings and the distribution of vessels in stems and roots.
The findings indicate a probable influence of the ground movement on the plants. The reaction wood in a Pinus cembra stem at the rockglacier front clearly suggests an increase in horizontal velocity in the beginning of the 1990s which is supported by velocities quantified by photogrammetrical analyses. Regarding the Salix helvetica shrubs, no obvious differences in ring width variations between the unstressed and stressed samples from the inactive and active rockglaciers, respectively, were found. However, a comparison of vessels within individual rings of the stressed and unstressed samples revealed general differences in size. Especially the vessels in roots taken from the inactive rockglacier tend to be larger than those from the stressed site.

Genetic control of tree ring response to climate characteristics in a maritime pine clonal test

Nahum M. Sanchez Vargas, Philippe Rozenberg, Catherine Bastien, Leopoldo Sanchez

Institut National de la Recherche Agronomique (INRA)

Short term variation of climate characteristics during the growing season affect cambium activity and thus characteristics of xylem cells deposited. In conifer trees growing under temperate climates, an X-ray microdensity profile drawn through a ring had reveal a pattern related with the variation of the balance between the water availability and the water demand during the fraction of the year where cambium is active: density can be understood as the level of tree response to specific environmental conditions. As a result we interpret within ring density variation as phenotypic plasticity of tree response to environmental changes. This work presents some results concerning the clonal variation of the characteristics of the relationship between density and climatic data, estimated at the tree levels for three selected rings. A drought index explaining the within-ring density data was constructed. Genetic parameters were obtained for both the parameters of the ring density model and the parameters of the relationships between the ring density model and the within-growing season drought index. The genetic parameters describing the clonal control of the tree response to withing-growing season climate variation can be interpreted in terms of adaptation.


Growth layer formation in Avicennia marina: the story beyond

Nele Schmitz (1,2), Anouk Verheyden (2), J.G. Kairo (3), Hans Beeckman (2) and Nico Koedam (1)

(1) Vrije Universiteit Brussel (VUB), Laboratory for General Botany and Nature Management (APNA), Pleinlaan 2, 1050 Brussels, Belgium.
(2) Royal Museum for Central Africa (RMCA), Laboratory for Wood Biology and Wood collection, Leuvensesteenweg 13, 3080, Tervuren, Belgium.
(3) Kenya Marine and Fisheries Research Institute (KMFRI), P.O. Box 81651, Mombasa, Kenya.

On sanded stem disks of the mangrove Avicennia marina (Avicenniaceae) a distinct pattern of light coloured phloem bands and darker xylem bands can be observed. However, few studies have addressed the controlling factors of the successive cambia that create these growth layers. Whereas Chapman (1947) considered the rings to be annual, Gill (1971) found them to be related to stem diameter and suggested an endogenous control. The aim of this study is to establish whether the growth layer formation of A. marina is characterized by a certain periodicity and whether it is influenced by environmental factors such as salinity and inundation frequency.
First, the non-annual character of the growth layers is demonstrated. An annual formation of three growth layers as compared to a half is found in three plantation trees of known age and three cambially marked trees respectively. As suggested before the prime determinant of the production of new cambia is presented to be stem size. However, the relationship between growth layer width and environmental factors is noteworthy. Based on an additional 28 stem disks from three study sites we noticed a decrease in growth layer width with increasing salinity and/or inundation frequency of the site. Although the relation is not necessarily linear it implies that the possibility of age estimations based on growth layer count can not be excluded yet, at least within one site. It is concluded that the banded pattern of A. marina is unsuitable for dendrochronological applications. Nevertheless, the functional and/or mechanical significance of the variation in growth layer width offers interesting perspectives.

References
Chapman VJ. Secondary thickenings and lenticels in Avicennia nitida. Proceedings of the Linnean Society 1947;158:2-6.
Gill AM. Endogenous control of growth-ring development in Avicennia. Forest Science 1971;17(4):462-465.


Life spans of herbs and dwarf shrubs

Fritz Schweingruber

Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland

Most dwarf shrubs and dicotyledonous herbs from temperate climates form distinct annual rings. Rings are best expressed in the transition zone between shoot and root. Determination of plant ages is possible in all individuals with taproots.
The oldest dwarf shrub is a Rhododendron ferrugineum with 202 rings and the oldes herb a Draba aizoides with 43 rings.
Annual ring analysis allow the reconstruction of vegetation establishment processes in glaciar forefields, sea shores and recultivated land give important informations about the development of the vegetation after fires or different land and meadow managements.
Xylem anatomy and ring counting of herbs open a new playground for wood anatomists. The anatomical structures of thousends of new species can be related to plant systematic criterea, life forms, growth forms, climatic zones and sites.


Oak dendrochronology at the Basque Country

Josue Susperregi

ARKEOLAN, Dendrochronology Laboratory, Francisco Gainza, Nº 4, 20302 Irun, Spain,  

Arkeolan was created in 1989 as a centre for historic and archaeological research, and it is placed at Irun (north of the Basque Country).
Between its activities, we could outstand the archaeological excavations of roman sites, medieval towns, necropolis and fortifications, and the studies of roman mining, medieval and post medieval iron working, roman and medieval pottery, and shepherds settlements from the Bronze Age to medieval and post medieval times.
Because of the excavation of the roman port of Oiasso in 1992, and the datation of its wooden structure by dendrochronological methods, an interest was shown to build up a reference chronology for the Basque Country. Oak was chosen as the reference specie, as it has been used since prehistoric times at the construction of buildings and many other structures.
Since 1998 until this moment, more than 2000 samples have been recollected from living trees, timbers, beams and archaeological woods. In the beginning the sample recollection from living trees was focused on the Gipuzkoa Territory. Great difficulties were found because of two particularities of our working area: on the one hand, and due to its complex orography, eight local chronologies had to be elaborated in order to build up a regional curve; on the other, a extremely complacent growth, with really large increment rings, made it really difficult to find living trees older than 200 years. The solution became when the sampling area was extended to other basque territories like Araba, where there was a transition to the continental climate, with less precipitations and more variable temperatures. Thanks to this fact, it was possible to create an almost 400 years long chronology from living trees of the specie Quercus faginea. By using this chronology, lots of timbers coming from different sites have been dated, and finally a reference curve that reaches to the end of the XIVth century has been built up. The next objective will be, besides the curve extension to the past according to the wood disponibility, the series analysis in order to obtain climatic data, and, at an early future, begin with climatic reconstructions.


Twentieth century as the wettest period in Northern Pakistan over the past millennium

Kerstin Treydte (1), Gerhard Schleser (2), Gerhard Helle (2), David Frank (1), Matthias Winiger, Gerald Haug, Jan Esper (1)

(1) Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland
(2) Forschungszentrum Jülich, Institute für Chemie und Dynamik der Geosphäre ICG-V, Abt. Isotopengeochemie und Paläoklima, D-52425 Jülich.

There is evidence that 20th-century warming could lead to increases in the moisture holding capacity of the atmosphere altering the hydrological cycle and the characteristics of precipitation. Despite the existing co-variability of both climate variables, attention in long-term climate reconstruction has recently concentrated on temperature changes. We present the first annually resolved oxygen isotope record from tree-rings, providing a millennial-scale reconstruction of precipitation variability in the high mountains of northern Pakistan. Low-frequency variations reveal dry conditions at the beginning of the past millennium, and through the 18th and early 19th centuries, with precipitation increasing during the late 19th and the 20th century to yield the wettest conditions of the last 1000 years. Comparison with long-term precipitation reconstructions from synoptically different regions like Europe or Western USA indicates a large-scale intensification of the hydrological cycle coincident with the onset of industrialisation and global warming. Its unprecedented amplitude argues for a human role.

Treydte, K., Schleser, G.H., Helle, G., Frank, D.C., Winiger, M., Haug, G., Esper, J. 2006: Twentieth century as the wettest period in Northern Pakistan over the past millennium. Nature, in press.

Fire-climate interactions in the Mediterranean climate areas of California, Southern Oregon, and Western Nevada

Valerie Trouet, Alan Taylor

The Pennsylvania State University, Department of Geography, 302 Walker Building, 16802-5011, University Park, PA, USA

Wildland forest fires are, and have been, an important process shaping forest ecosystem structure and function in the fire-prone Mediterranean Climate Area (MCA) forests of the North American Pacific Coast. The long-term and large-scale suppression of fire activity in many forests in the Western U.S. has led to an increased risk of devastating fires because fuels are allowed to build up to unnaturally high levels. The development of prefire management plans, with a primary goal of reducing the build-up of fuels, is critical to alleviate loss of life and property associated with wildfires and to facilitate long-term sustainability of forest ecosystems in the region. Understanding the role of wildfire in forest ecosystems and the factors influencing wildfire behavior is essential for the development of these management plans.
The goal of this study is to identify the relationships of inter-annual and intra-decadal climate variation and multi-decadal and multi-century climate change on sub-regional variation in fire regimes in the MCA of the Pacific Coast. The fire occurrence variation on a sub-regional to regional scale over periods of decades to centuries is determined using fire scar chronologies as a proxy of fire activity. Long-term fire-scar records were collected at more than 50 sites, extending from northern Baja California to Southern Oregon. The variation in fire occurrence is related to multi-century tree-ring reconstructions of climate (temperature, precipitation, PDSI) and dominant modes of circulation (PDO, ENSO, PNA).

Analysis of rootwood of Scots pine

Hanuš Vavrčík, Vladimír Gryc, Michal Rybníček

Mendel University of Agriculture and Forestry Brno, Faculty of Forestry and Wood Technology, Department of Wood Science, Zemědělská 3, 613 00 Brno, Czech Republic

Dendrochronological and anatomical analysis of rootwood of Scots pine (Pinus sylvestris L.) tree was carried out. The relation (synchronization) between widths of rings in the root and widths of rings in the stem was studied. We supposed that widths of rings in root may be the valuable source of ecological signal the same as widths of rings in stem. Ring analysis of stem was carried out for comparison. The curves of ring widths of horizontal roots were synchronized together with high values of the corelate coeficient and paralellism coeficient. The curves of ring widths of roots were synchronized with ring widths of tree stem.
Radial diameters and thickness of cell walls of tracheids were measured in one horizontal root (8 m in length total). Rings of root from part close to the stem base shown the similar structure (earlywood and latewood portion) as stemwood rings. Rings visibility and portion of latewood decreased along the root length (from the stem base to the root tip). Latewood of each ring in rootwood was formed only by one or two tracheids in each radial row. False rings occurred frequently in rootwood.
The number of tracheids per ring decreased along the root length. The radial dimension of tracheids increased along the root length.
There were different trends of the dependency of the radial dimension of tracheids on the relative position of tracheid within ring (root section 0.2m from the stem base).
The radial dimensions of tracheids decreased from earlywood to latewood within rings close to cambial zone. On the other hand the dimensions increased within almost whole ring in rings that were close to the central part of the root. Remarkable decrease of the radial dimensions of tracheids was observed in last tracheids of each ring. Variability of cell wall thickness of tracheids from central part of root was lower than variability of tracheids from rings close to cambial zone (valid for section taken from 0.2m from the stem base).
The project was financially supported by the research plan of LDF MZLU in Brno, MSM 6215648902.

Radial growth as influenced by light and nutrient availability

Pascale Weber, R.D. Bardgett

Department of Biological Sciences, Lancaster University, Lancaster, LA1 4YQ, United Kingdom

Tree growth is, besides endogenous factors, influenced by various exogenous factors such as light and nutrient availability. However, the relative importance of belowground properties related to nutrient availability for tree growth and regeneration has not yet been studied. In this study, we combined dendroecological with soil ecological methods to investigate how single freestanding trees influence soil properties and thereby the growth of regenerating trees in their neighbourhood zone. We tested the hypothesis that soil properties affect the radial growth of the regeneration besides light availability and browsing pressure.
In a remnant of the old Caledonian forests in Scotland, 16 old and dominant Scots pine (Pinus sylvestris L.) trees were chosen. These trees can be described as making up a patch on their own and probably causing a gradient in light and nutrient conditions from their stems to their outer crowns. Around each tree, soil samples were taken and the vegetation was recorded in three zones, defined as inner, middle and outer zone of influence. Increment cores of both the dominant and adjacent regenerating trees were extracted to measure the age and the radial growth of each tree.
Soil properties, such as moisture content and availability of different nutrient forms, were found to differ among the three zones. These differences might be explained by several processes, such as the tree’s water uptake and transpiration, the needle litter input to the soil, which alters the decomposer community and nutrient cycling, and root actions.
The results of the soil ecological analyses together with forthcoming light measurements at each tree are aimed at revealing the relative importance of below- (nutrients) versus above- (light) ground factors for the abundance and growth of Scots pine regeneration in the forest remnants. Currently, regenerating these forests is mainly based on reducing browsing intensity by fencing and by downsizing dear populations through culling. With this study, we hope to provide new insights in the regeneration ecology of Scots pine with respect to light and nutrient requirements to further enhance conservation and management strategies.

Reconstructing the flow of the river Nile from carbon isotopes and other proxies in Juniperus procera tree rings

Tommy H.G. Wils (1), I. Robertson (1), Z. Eshetu (2) & M. Gagen (1)

(1) Department of Geography, University of Wales Swansea, Singleton Park, SWANSEA SA2 8PP, United Kingdom
(2) Ethiopian Agricultural Research Organization (EARO), PO Box 2003, ADDIS ABEBA, Ethiopia

The aim of this project is to extend the limited discharge records of the river Nile by several centuries using carbon isotope ratios and other proxies from tree rings in 400-year-old Juniperus procera trees growing at a number of sites in Northwest Ethiopia.
The resulting hydrological and climatic records will highlight the influence of climate change on Nile discharge and improve water resources management in the basin, which is of great importance due to the increasing population depending on the Nile waters for agriculture and electric power.
Rainfall in the Ethiopian Highlands accounts for most of the Nile waters in Egypt through the Blue Nile, Atbara and Sobat rivers. Carbon isotope ratios in trees are strongly related to precipitation through its influence on stomatal conductance. However, this proxy is also influenced by varying rates of photosynthesis. This project will assess the impact of these competing influences by determining carbon isotope ratios, tree-ring widths, tree-ring density and earlywood-latewood ratios. All proxies will be measured at annual resolution and from at least five trees to ensure an adequate degree of replication. The reconstructed flow of the river Nile will be validated against historical measurements from the Rauda Nilometer in Cairo, Egypt.

Abstracts of posters (abstracts of talks see above)

Dynamics of subalpine forest communities characterized by Abies alba in the northern dry Alps ( Savoy, France)

Fabien Beilhe, Sandrine Chauchard, Christopher Carcaillet

Center de Bio-Archaeology and Ecology (UMR5059, CNRS/EPHE/UM2), Institut de Botanique, 163 rue Broussonet, 34090 Montpellier, France,

Land-use abandonment is a driving force behind intense forest dynamics in the European mountain regions. Silver fir (Abies alba), a well known late successional species, susceptible to humidity, regenerates well in areas above 2000 m asl, known to be its growing limit. We aim to study whether the fir establishment in subalpine forests dominated by cembra pine (Pinus cembra) and larch (Larix decidua) is either a process dependent on land-use abandonment, or linked with global warming, or whether it is a late successional mechanism. Forests are situated in the northern slope of a dry continental valley in the western Alps. Thirty-one (31) forest stands were sampled above 2000 m asl. Stands measure 314 m 2 and are centred within a ray of 10 m around a silver fir. All trees and seedlings are collected for tree-ring counting and basal area measurements. Trees with ø>5 cm are sampled with a Pressler corer, and all individuals with ø<5 cm are cut at collar. Height was measured only on individuals with ø<5 cm. Firs were found up to the exceptional elevation of 2250 m asl, i.e. 100 m below the upper tree-line. Stands are co-dominated by cembra pine and larch, followed by spruce (Picea abies). Most stands contain only one fir. Tree age structure varies greatly between stands. Rare cembra pine and larch regenerated during the 18 th century. The age structure indicates an increase in tree density during the 20 th century, which is exponential since the 50’s. The main net regeneration concerns Pinus cembra. The pattern of fir regeneration covers the 20 th century and follows the same temporal distribution as the other species, although it remains infrequent. We observe a large variability between the age of silver fir individuals and the mean age of forest stands, suggesting independence between the forest stand age and the timing of fir regeneration. The sporadic age/structure of Abies alba through the 20 th century suggests an hazardous process of regeneration, likely independent from climate, but linked to the same process affecting the other species, i.e. the known regional land-use abandonment.

Comparison of different avalanche and debris flow study areas in terms of growth disturbances occurrence in tree rings

Marco Bezzi, M.G.Cantiani, M.Ciolli

University of Trento , Department of Civil and Environmental Engineering, via Mesiano 77, I-38100 Trento, Italy

Investigation on the best choice of growth disturbances in tree-rings can optimize dendrochronological procedures for avalanche and debris flow reconstruction. To improve the knowledge on growth-disturbance indicators and to investigate new approaches for data analysis different study areas were selected in Trentino Alto Adige ( Italy) within the Stelvio National Park and the Paneveggio National Park.
Approximately 850 cores from different tree species were collected and examined for the analysis of growth anomalies caused by avalanches or debris flows, with anomalies including compression wood, abrupt growth reductions and releases, traumatic resin ducts and scars. Data were analysed to find the most reliable tree ring indicator for the frequency reconstruction of avalanche and debris flow phenomena. Firstly, the percent presence of each indicator was analysed. Secondly, a nonparametric statistical test was applied to the data set. And thirdly, an additional methodology was applied to the data set to investigate fluctuations in the frequency of the phenomena, through comparison of different combinations of the selected indicators. The analysis of growth disturbances over time made possible the reconstruction of the frequency of avalanche and debris flow activity over the last 50 years and, in some areas, over the last century.
A detailed analysis of one of the avalanche tracks provided interesting results as regards the reconstruction of avalanche dynamics and a mathematical model validation. Analysis of scars on buried stems of Pinus Sylvestris also provided interesting results in terms of debris-flow-volume estimations. This research, financed by the Italian National Institute for Mountain Research (IMONT), confirms again the potential of dendrochronological reconstruction of past geomorphological events and demonstrates the technique’s greater precision compared with other available methodologies currently applied.

Study of the elemental concentration variation of (metals) Mn, Fe, Cu, Zn and Pb in rings of growth of Abies religiosa and Pinus montezumae from Mexico Valley Surroundings

German Calva-Vázquez (1), G. Razo-Angel (1), P. Flores-Nieves, M. Hernández-Tapia, Cruz-Munoz, A.R., L. Rodríguez-Fernández (2) and J.L Ruvalcaba-Sil (2)

(1) Laboratorio de Contaminación Atmosférica, FES Zaragoza, UNAM, Calzada I. Zaragoza esq. Av. Guelatao s/n, 09230, Mexico, D.F., México.
(2) Instituto de Física, UNAM, Apartado Postal 20-364, 01000, Mexico, D.F., México

It is accepted that the elemental concentration in the rings of growth of trees are related to growth conditions and the elements abundance in the soil. Pine and fir species have been used to study pollution, human activities effects and volcanic eruptions on forests. In this work, a study of the variations of metallic elements contents in rings of summer and spring growth of pine (Pinus montezumae) and fir (Abiesreligiosa) from forests from Mexico Valley is presented.
The tree cores were extracted by a 5 mm diameter stainless steel Pressler drill from trees from El Chico (ECP) and Desierto de los Leones (DDLP) National Parks. These forests are respectively at 70 km North and 20 km South from Mexico City. Twenty trees were chosen randomly in regions from 2800 to 3200 m over the sea level.
For the elemental analysis of the cores, Particle Induced X-ray Emission Spectrometry (PIXE) was used. The extracted cores were dried at 100 oC for 48 hours before the irradiation. Each ring in the tree core was irradiated by a collimated 0.5 mm x 3 mm proton beam under a helium atmosphere. X-ray emitted and backscattered protons were collected simultaneously using a LEGe detector and a particle detector, respectively. Then, rings corresponding to the last 30 years were analyzed individually for monitoring pollution and environmental conditions in the Mexico Valley.
Typical elements registered in the rings were: Mn, Fe, Cu and Zn. Pb were not observed in all the rings. Their variations of concentration in the tree rings indicate that these elements are related to volcanic eruptions, soil acidity changes and growth conditions of trees.

Authors thank the technical assistance of K. López and F.J. Jaimes for the accelerator operation. This work was supported by a DGAPA-UNAM grant under contract IN216903.

Annual formation of tree rings in Quercus ilex L. in NE Spain: the support of dendrometers data and climate

 Filipe Campelo (1), E. Gutiérrez (2), M. Ribas (2), C. Nabais (1) & H. Freitas (1)

(1) Departamento de Botânica, Universidade de Coimbra, Calçada Martim de Freitas, 3001-455 Coimbra, Portugal
(2) Departament d’Ecologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal, 645, 08028 Barcelona, Spain

Tree rings are generally induced by seasonally alternating favourable and unfavourable growth conditions. Under Mediterranean climate, besides the cambial dormancy during the cold winter, exceptional dry and warm summers can induce cambial resting, with consequent formation of a double ring during the same calendar year (i.e. false rings), making extremely difficult the correct dating of their growth rings. Due to the difficulties on tree ring identification dendrochronological studies are scarce in Mediterranean areas. The present study was carried out to check the annual formation of tree rings of Quercus ilex and compare the radial growth response to climate at three heights categories: lower (0 and 0.3 m); middle (0.6 and 0.9 m) and upper (1.2 and 1.5 m). Ten trees were felled in an unmanaged 22-year-old stand coppice, in NE Spain . Data from 10 dendrometer bands were used to aid the accuracy of the tree ring identification. The good synchronization between discs from the same tree and from different trees, the correspondence of tree-ring width with dendrometer measurements and the narrow tree-rings with dry-summer years confirmed that Q. ilex formed annual rings in the study area. The structures of lower, middle and upper standard chronologies were the same after standardization and responded similar to climate.

Influence of extreme climatic condition on radial growth of Norway spruce along an altitudinal gradient in the Šumava Mountains

Alzbeta Cejkova

University of South Bohemia, Faculty of Biological Sciences, Branisovska 31 Ceske Budejovice, 370 05 Czech Republic

The growth of trees is influenced by many ekological factors from which climatic conditions and altitude are essential. Each region has its specific macroclimatic conditions which represent the main determining signal for growth of trees in this area. Specific diversity of macroclimatic conditions exists simultaneously in this region. Climatic conditions show being modified by terrain morphology, elevation, exposition etc. in tree-ring series in particular site. Growth response of woody species to climatic conditions can vary within a relatively small area. These differences of the growth response are more obvious in extremely climatic events – pointer years. This situation is detected even on relatively small range of elevation and central european climate in the region of the Šumava Mountains, Czech Republic. The aim of this study is to find out what influence the extreme climatic conditions have on the growth of Norway spruce (Picea abies) in the region of the Šumava Mountains and whether this influence is different or similar in different elevation zones. Principal component analysis, correlation matrix and hierarchical cluster analysis identified three altitude zones for seventeen Norway spruce chronologies in the region (low < 698 m; intermediate 760 – 946 m, high > 979 m a. s. l.). Event years were detected using five-year moving window in measured tree-ring width series. The pointer year was determined, when event year was detected in 50% of tree-ring width series. Comparison of pointer years occurrence for common time span 1922 – 2000 shows different limits for the growth of spruce along altitudinal gradient in the study region. Trees from low and high elevation zones have not the same pointer years. Trees from intermediate elevation zones show some pointer years identical with trees from lover elevation zone, which point on gradual change of growth response to climatic condition in this part of altitudinal gradient.

Large herbivores control the invasive potential of non-native Austrian black pine (Pinus nigra ssp. nigra) in a mixed deciduous Mediterranean forest.

Sandrine Chauchard, Gaëlle Pille, Christopher Carcaillet

Centre de Bio-Archéologie et d’Ecologie (UMR 5059 CNRS), Institut de Botanique, 163 rue Broussonet, 34090 Montpellier, FRANCE

The invasive potential of the non-native Austrian black pine (Pinus nigra ssp. nigra Arn.) was analyzed in a 100-year old Mediterranean mixed deciduous forest in the Massane Nature Reserve, eastern Pyrenees ( France). The reserve holds ca. 120-150 semi-feral cattle (Bos taurus L.) that browse and trample the woody regeneration. Tree age structure was by dendrochronology to reconstruct the pine population dynamics in grazed and non-grazed (fenced in 1954) portions of the forested reserve. The age structure of the pine population regenerating before 1960 was similar between the inside and outside of the enclosed reserve area. Since 1960, pine recruitment has occurred only in the non-grazed area. The diameter variability with age changed since the 19th century. For pines <20-years old, the diameter variability is low, whereas it is very high for individuals older than 100 years. Diverse forest structural changes (composition, canopy height and density, etc.) likely explain the variability in diameter at a given age. Cattle do not appear to affect tree growth as it is similar inside and outside the fenced area, but they control the regeneration of non-native Austrian black pines, which can spread in the absence of cattle. If non-native black pine poses a risk for forest conservation, large herbivores may play a useful role in maintaining this species at low abundance.

Drought response on hydraulic architecture of Quercus pubescens Willd. and Pinus sylvestris L. in the Wallis Valley, Switzerland

Md. Qumruzzaman Chowdhury (1), U.G.W. Sass-Klaassen (1), F.J. Sterck (1) and Roman Zweifel (2)

(1) Forest Ecology and Forest Management group, Center for Ecosystem Studies, Wageningen University, PO box 47 , 6700 AA Wageningen, The Netherlands
(2) Institute of plant Science, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland

The hydraulic architecture was studied for pubescent oak ( Quercus pubescens Willd. ) and scots pine ( Pinus sylvestris L.) at Salgesh in the Wallis Valley, Switzerland. The hydrology of the dry area was only influenced by precipitation whereas in the wet area additional water is supplied by a water channel. Trees were selected on the basis of similar diameter for both species in each site. Wood cores were collected from 50 cm above the ground for dendrochronological and wood anatomical analysis. Trees of the dry site were older than those from the wet site along the water channel. Ring width is positively correlated with the precipitation in and prior to the growing season (previous September to current October) in both species on the both sites. Previous winter and current spring precipitation is positively correlated with tree growth in each case. Summer temperature is negatively correlated with tree ring width and latewood width of oak.
Leaf specific conductivity was calculated for each tree as the ratio between stem conductance and total leaf area. Stem conductance depends on sapwood area, conduit diameter and conduit density (stem conductance ~ sapwood area * (conduit diameter) 4 * conduit density) (leaf specific conductivity ~ (stem conductance) / total leaf area)
Leaf specific conductivity is considered a measure of the ‘water supply sufficiency’ of a stem to the leaves supported by that stem. For both pines and oaks, leaf specific conductivity was lower at lower water availability. The positive effect of water availability on stem conductance was mainly due to changes in sapwood area, and only slightly by conduit diameter and density. Since water availability had a stronger effect on stem conductance than on total leaf area, leaf specific conductivity was higher in trees of the wet site. Similar results were found for oak. Thus, in both species, trees had more efficient water supply to leaves in the wet site. Trees of dry sites apparently suffered from limited radial growth, limiting the water supply sufficiency. The decline in leaf specific conductivity with tree diameter may ultimately limit tree size in either site.

Dendrochronological monitoring of air pollution in the Ghent canal area

Maaike De Ridder

Royal Museum for Central Africa, Laboratory for Wood Biology and Xylarium, Leuvensesteenweg 13, 3080 Tervuren, Belgium  

In this study, tree rings patterns of three indigenous species – 50 pedunculate oaks ( Quercus robur L. ), 30 beeches (Fagus sylvatica L.) and 30 pines (Pinus sylvestris L.) - were used to investigate the influence of air pollution by heavy metals. The emission of heavy metals is assumed to be a possible limiting factor for tree growth. Tree ring analysis was done on tree cores sampled on the grounds of an important steel producer with high emission values ( Sidmar NV). Reference plots with lower emission values were situated in two nearby forests, Kloosterbos and Heidebos. The three forests have similar stand and soil properties.
Climatologic variations and individual growth trends were filtered out of the tree ring series to receive a signal that strengthens the external disturbances. Years with extreme low or high tree ring values (pointer years) were defined and compared with important events in the history of the Ghent canal area. The conclusions of this comparison are hard to determine statistically. Another option is the study of trends in radial increment and emissions of heavy metals in the air. Emission data for nine years (1995-2003) were available for lead and zinc. Unlike lead, zinc emissions have a significant influence on the radial increment for this period. The tree ring series of every plot of pedunculate oak (Sidmar and reference plots) showed a consistent, negative correlation with the trend in zinc emissions. This means that high zinc emissions corresponded with low radial increments and vice versa. Despite this significant result it is not advisable to draw a final conclusion on the influence of zinc on the tree rings of pedunculate oak. The emission data only covered a short period and were the result of different emission sources. A longer data set, based on the emissions of one source, and the modeling of the plume of smoke from this source can provide further evidence. Meanwhile, it is not possible to determine one specific species as a monitor for air pollution by heavy metals in the Ghent canal area.

Phenotypical modifications of Siberian larch in the ecotone of the upper forest bound at Polar Urals, Russia

Nadezda Devi

Institute of Plant and Animal Ecology. 8 Marta Str, 202, Ekaterinburg, Russia, 620144

Phenotypical modification, or an ability to exist in a number of different growth forms, is a basic adaptation of Siberian larch trees to severe climatic conditions in the Polar Ural mountains ( N 66 040’, E 65 035’).
We devide mat, creeping, multi-stemmed or arborescent growth forms of Siberian larch, that can change one to another under the change of environmental conditions.
Using dendrochronological technologies we’ve dated the remains of previous growth forms and restored a history of climate change in the ecotone of the upper forest bound at Polar Urals for the tree lifetime period.

The work is performed with financial support of the grants RFFR 04-04-48687and INTAS 04-83-3788.

Dendrochronological techniques applied on standing structures: a pilot study on the Czar Peter House in Zaandam, The Netherlands

Marta Domínguez Delmás (1), Tamara Vernimmen (1) & Gerard Horneman (2)

(1) Hollandia Archeologie / DendroLab NL, Tuinstraat 27ª, 1544 RS Zaandijk, The Netherlands, www.dendrolab.nl
(2) Zaans Museum / Czaar Peterhuisje, Krimp 23, 1506 AA Zaandam, The Netherlands,

August 1697. Czar Peter the Great arrives in Zaandam, the Netherlands, determined to become personally acquainted with the arts of shipbuilding, which Dutchmen are famous for. Zaandam was at that time the most important centre of such craftsmanship and the Czar had planned to stay the whole winter. The massive attention he received from the local population, however, forced him to leave after only 8 days.
During his short stay, Peter the Great was lodged at a small and humble wooden house, which was built, like many of the houses in the Zaandam area, with planks from boats taken apart at the local wharfs. The impact of his visit was so strong that the little dwelling was later turned into a museum and has become a place of pilgrimage for Russians and historians all over the world.
Still, certain parts of the Czar Peter House have been altered over the last centuries to safeguard the integrity of its structure. However, traces of further alterations have been found which do not appear to be documented.
In order to identify and date the modifications the house was subjected to, a dendrochronological pilot study has been undertaken in collaboration with the Zaans Museum/Czaar Peterhuisje. Due to the fact that the house is a protected historical monument none of the usual techniques apply. Therefore the tree-ring pattern of the planks had to be measured in situ using a relative or non-fixed scale, in the radial to tangential section. No preparation of the surface was allowed. Micro-samples were taken for wood identification in non-visible parts of the planks.
Preliminary results show three different wood species present in the house: Abies alba Mill., Picea abies L. (Karst.) and Pinus sp. Synchronisation between planks proved possible in some cases. The dating of the index series is still pending as the research is ongoing. Provenance of the samples will also be investigated. Recording and dating the tree ring patterns of conifers in the radial/tangential section with a relative scale has proved to be a challenge, yet not impossible.

The use of stable Sr isotopes in dendrochemistry: biomonitoring and understanding of tree physiological processes

Thomas Drouet (1), D. Demaiffe (2), and J. Herbauts (1)

(1) Laboratoire de Génétique et d’Ecologie végétales, Université Libre de Bruxelles (ULB), chaussée de Wavre 1850, B-1160 Bruxelles, Belgium
(2) Laboratoire de Géochimie Isotopique, Université Libre de Bruxelles (ULB), CP 160/02, av. F.D. Roosevelt 50, B-1050 Bruxelles, Belgium.

Acidification of forest soils by atmospheric deposition involving leaching of nutrient cations is still an active subject of research. Many studies made in Europe and North America have shown an increasing depletion of exchangeable base cation that may cause tree nutritional deficiencies in sensitive soils. The two main sources of Ca delivered to forest ecosystems are mineral weathering release and atmospheric deposition. We use the strontium isotopic composition ( 87Sr/ 86Sr) to determine the origin of Ca in forest stands. Strontium can be used as a proxy of Ca because these ions have similar chemical structure and behave similarly in the soil and plant compartments [1]. Tree-ring analysis of Sr isotopes provides information on past condition and on the evolution of Ca availability over time. Dendrochemistry assumes that a change in tree-ring chemistry reflects the historical pattern of change in the soil solution. The main objectives of this study were (a) to verify the reliability of the tree-ring recorder; (b) to evaluate the contribution over time of mineral weathering and atmospheric deposition of Ca to tree nutrition.
The reliability of the tree-ring recorder was verified using a well-controlled nutritional perturbation induced 30 years ago in a forest stand by a liming operation with a known liming Sr isotopic signature. The Sr isotopic dendrochemical pattern showed that the wood isotopic ratio was influenced about 50 years before the liming application date. That can be explained by the lateral re-equilibration process: the conducting cross-section is continuously reequilibrated with cation from the mineral sap (influenced by current soil solution) until the inactivity of the ring. So, this process could foredate by several decades the isotopic signature observed in a growth ring.
In this limed stand, we don't observe significant change in the Sr isotopic signature between different wood components (total wood cation and hydrosoluble cation), commonly considered as fractions with different mobility [2]. Therefore, measurements of 87Sr/ 86Sr ratios in several wood components can be used as a tool for a better understanding of inter-annual cation exchanges between tree-rings.
In other forest contexts, we performed strontium isotope dendrochemical analysis to monitor possible change of tree source of nutrient [3]. Strontium isotopic ratio was measured in beech wood (Fagus sylvatica L.) growth rings in 4 sites and in pedunculate oak (Quercus robur L.) tree-rings in one site (chronologies of 130 to 180 years). We observe a steep decrease from pith to outer wood of the Sr isotope ratio from ~1870 to ~1920 in the stands developed on soils with a poor Ca status. Assuming the contribution of atmospheric deposition (low 87Sr/ 86Sr ratio) to the soil to be constant during this period, a change toward a lower Sr isotope ratio in younger wood must result from a decreasing contribution of Sr from the weathering source (high 87Sr/ 86Sr ratio). This may occur when cations are displaced from the soil exchange complex by acidic deposition at a rate faster than they can be replenished by mineral weathering.
Our data suggest that forest ecosystems were affected by atmospheric inputs of strong acids earlier than previously thought. Similar patterns of decrease in Sr ratio over time in bolewood of different tree species found by other authors in Scandinavia and northeastern USA may indicate that this process is a general feature in industrial regions.

References
[1] Drouet Th., Herbauts J., Gruber W., Demaiffe D. (2005) Geoderma126: 203-223.
[2] Herbauts J., Penninckx V., Gruber W., Meerts P. (2002) Can. J. For. Res. 32: 1829-1837.
[3] Drouet Th., Herbauts J., Demaiffe D. (2005) Global Change Biology11: 1926-1940.

Pinus sylvestris tree-ring size differences at breast-high and at base level in different habitat types in Latvia

Didzis Elferts, Roberts Matisons, Zane Striķe, Guntis Brumelis

University of Latvia , Faculty of Biology, Kronvalda bulv. 4, Riga, Latvia, LV-1586,

In dendrochronological studies, samples from living trees are usually taken at breast height (1.3 m), due to the tree taper and to standardize methods. However, these cores do not give the true age, and the error cannot be objectively estimated for shade tolerant trees as it can range from 10 to 100 years for some species such as Picea abies. The aim of this study is to determine if the similar patterns of variability of tree-ring width can be obtained by coring at/near tree base and at breast height for Pinus sylvestris.
Samples of tree-rings from pines were taken in two different habitat types of Latvia using coring. One area was a coastal dune system in Latvia, where trees that had fallen on the dune system from a bluff beach after a storm were cored. Some when standing had been buried by sand up to a height of 1 m. The other site was a mire where previous study had found the oldest tree (454 years) in Latvia. Samples were taken at 1.3 m from the base and at the base. Three cores were removed in different directions at breast height.
Tree-ring sizes were measured using the program LignoVision or a LINTAB III measuring table. Tree-ring series were dated, then two chronologies for every site were built – one from tree-ring series at breath-high and one from tree-ring series at base-level. Those two chronologies for every site were compared using correlation analyses, and also the relation of each chronology to climatic factors (temperature and precipitation) was determined. Information on temperatures and precipitation were available starting from 1850 for the Riga region and from 1924 for other regions.

This study was partly financially supported by European Social Fund.

Tree-growth based management system to realize rules of nature conservation

Stefanie Fischer, Burkhard Neuwirth, Jörg Löffler

University of Bonn, Department of Geography, Meckenheimer Allee 166, 53115 Bonn, Germany

Nowadays, laws of nature conservation become more and more important in national and international politics. Rules like the FFH-RL (Fauna-Flora-Habitat Richtlinie) prescribe the installation of protected areas. The aim is the maintenance or improvement of the actual status of conservation of species worth to be protected. But it becomes obvious that status and development of conservation of forest-trees could not be proved by conventional ecological methods.
Dendroecology now offers the possibility to detect high-resoluted growth variations. Within this study temporal and spatial variations of tree-growth will be analysed over the period of 1900 to 2005. At the same time the influences of variable determining factors especially climate change and measures of nature conservation have to be examined. Due to the already existing dendrochronological network of the working group “Dendrochronologie” of the University of Bonn the research area will be Nordrhein-Westfalen. Further study sites will be arised to complete the data set necessary for this special project.
The central aim of this study is the development of a management system making possible the formulation of statements about the aptitude of different sites for realization of nature conservation rules with reference to the existing determining factors.

3D-modelling of roots - New application for analysing root system development

Holger Gärtner

Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland

Several attempts have been made in recent years to collect data on the morphology of root systems to represent their spread and size in three-dimensional space.
A practical tool to acquire data on the architecture of exposed root systems is the exertion of a magnetic field enclosing the root. A point-by-point exploration by means of a 3D-digitizer enables to measure and represent root lengths and bifurcations in three-dimensional space. The advantage of this method is the possibility to include branching order and branching pattern in the dataset. Regarding a more detailed analysis of total root structure, growth development as well as total and partial biomass measurements, the digitizing complexity would be too high. Further, no effort has been attempted so far to blend in tree-ring values into the digitized data. To realize this, a high resolution model of the root needs to be generated, which would necessitate an extensive digitizing work.
The application of a 3-D laser scanner to the admission of the structure of whole root systems, presented here, is a step towards the solution of this problem. Within Geosciences, laser systems are mostly used to generate digital terrain models. The possibility of receiving high resolution data (~1 mm) in short time combined with a fast and cost-effective post-processing of the data makes the data gathering and representation of highly complex structures a feasible task. At the Swiss Federal Research Institute WSL a ground based 3D- laser scanner was used in a feasibility study for the first time as a base to generate a three dimensional model of an exposed root system of a mature spruce tree. The study was accomplished to investigate the prospects and limitations of this technology.

Structure of Norway spruce wood (Picea abies /L./ Karst.) with the occurrence of reaction wood

Vladimír Gryc, Michal Rybníček, Hanuš Vavrčík

Mendel University of Agriculture and Forestry Brno, Faculty of Forestry and Wood Technology, Department of Wood Science, Zemědělská 3, 613 00 Brno, Czech Republic,

The presented project deals with the structure of Norway spruce wood (Picea abies /L./ Karst.) with the occurrence of compression wood. The macroscopic and microscopic description of wood were carried out on a selected sample tree along height and stem radius. The division of stem zones was based on the presence of compression wood (CW zone), opposite wood (OW) and side wood (SWL and  SWR zones).
In the macroscopic part, problems of the annual ring width were studied in relation to the position in a stem. Statistically significant differences were corroborated between particular zones. The compression wood zone showed larger width of annual rings and the higher percentage of late wood. The width of annual rings changed above all with the stem radius. Variability of the annual ring width with the stem height was not proved. The compression wood zone became evident in the lower part of a stem by dark colour and created crescents (severe compression wood). At higher positions, the continuous zone of compression wood was not created but annual rings showed only local enlargement (mild compression wood). Compression wood was formed in the lower part of a bent stem.
On the cross section, variability was studied of the width of tracheids in relation to their position in a stem. Statistically significant differences were found in radial dimensions of tracheids with the stem radius and height. On the basis of results obtained 3D models were constructed to describe spring and late tracheids in particular stem zones. Changes were described in the tracheid cross section within annual rings both with and without the presence of compression wood.
Statistically significant dependence of the change in the cell wall thickness within annual rings with the stem radius and height was demonstrated. The thickness of the tracheid cell wall in annual rings with the presence of compression wood showed a different trend as compared with annual rings from the opposite zone.
On tangential sections, the length of spring and late tracheids was measured. Differences between the length of spring and late tracheids were not proved in CW, OW and SWL zones. Only in zone SWR, statistically significant differences were found. The length of spring and late tracheids from CW zone demonstrated significant differences as compared with other zones. 3D models were crated from the results (for CW, OW, SWL and SWR zones; models for a spring and late tracheid) which depicted changes in the length of a spruce tracheid in relation to its position in a stem. Significant changes were found in the length of spring and late tracheids with the stem radius and height.
On a tangential section, statistically significant changes were found in dimensions of horizontal resin ducts with the stem radius and height. On the basis of results obtained 3D models were constructed (for CW, OW, SWL and SWR zones) which described variability in the diameter of horizontal resin ducts in relation to their position in a stem.
The project was financially supported by the research plan of LDF MZLU in Brno, MSM 6215648902.

Comparison of extreme conditions of the South and Polar Ural using frost rings in wood of Siberian Spruce

Marina A. Gurskaya

Institute of Plant and Animal Ecology, Ekaterinburg, Russia

Frosts during vegetation season damage xylem of coniferous trees and as result of this influence we can observe formation so-called frost damages within a tree ring. A degree of tree-ring damage, recurring frequency of frost damages and their position within the limits of the tree ring characterise severity of climatic conditions of tree growth.
We have collected cores of a Siberian Spruce (Picea obovata, Ledeb.) on three sites. Two sites are located at the upper tree-line of their distribution: on the Southern ( 1365 m a.s.l.) the Polar Ural ( 280 m a.s.l.) and third site is situated at northern tree-line beside at the bottom of mountain valley ( 90 m a.s.l.) on the Polar Ural. All chosen trees are growing in forest-tundra ecotone on good moistening place on southern slopes. Cores are collected at 0.2 m height of a trunk; the central ring was at 70 % of samples. It is known, that frost rings are formed at xylem of young trees in first 20-30 years. In total in our analysis we include only in 3000 year rings from each site for the Polar Ural and up to 30 000 rings for the South Ural.
The greatest quantity of damages is revealed at trees, growing at the bottom of mountain valley at the Polar Ural, namely 17 % from common number of tree rings, and the least amount (0.3%) was revealed at the upper tree-line of a wood on the Polar Ural. On the South Ural 10 % of tree rings is injured. Therefore further comparisons we carried out using frost damages of trees from the South Ural and the mountain valley bottom mountain valley at the Polar Ural.
To make our analysis more detailed and accurate we divided a tree ring into three parts: a beginning of earlywood (first 1-2 lines трахеид), other part of earlywood and latewood. Frost damage located in the beginning of early wood, indicate late spring frosts, in other part of early wood it shows early summer frosts and in latewood frost damage mark summer frosts. In tree from the South Ural frost damages prevail in earlywood. In latewood the amount of such damages is not much. On the contrary in the Polar Ural’ trees most frequently frost damages are revealed in latewood, that specifies high frequency summer frosts. The quantity of frost damages into both parts of earlywood is much less in comparison with their quantity in late wood, and it is a little bit less, than their amount in tress at the South Ural. Hence, on the South Ural the most widespread and catastrophic events for tree species are late spring and early summer frosts. Feature of the Polar Ural’ climate, which specifies severity condition for wood plants, is the high frequency of repeatability and catastrophic of summer frosts and rather low frequency late spring frost. Early summer frosts are observed approximately with the same frequency and force, both at the South and the Polar Ural.
We revealed years, when frost rings are formed per the same year both on the South and the Polar Ural. There are 23 common years when frost damages form in earlywood in two compare sites. However probability of casual concurrence of formation of damages shows that in early wood of damage are formed rather independently. Only strong frost, when trees have a high share of frost damages were observed on the large territory. These are 1916, 1935, 1951, 1956, 1995. The damages revealed in late wood, are formed under influence strong frosts, widespread on all Ural’s mountains.
The temperature conditions of years with frosts are determined. Agrees by the instrumental data of meteorological supervision, on the South Ural temperatures damaging spruce xylem is high than on the Polar Ural. However, it is necessary to take into account, that meteostation on South Ural is on 1000 м below the site where we collected samples, than on Polar Ural. Hence, we can suppose that the injuring temperatures are equal on the South and the Polar, or even below, than in the mountain valley bottom on the Polar Ural.
In conclusion, upper tree line of the South Ural is characterise extreme events like strong frost in late spring, upper tree line of the Polar Ural has cold vegetation season but without any strong frost. Strong summer frost, which reduce vegetation season till several weeks at the Polar Ural, we can reveal on the bottom of the mountain valley.

True and false rings in Toona ciliata

 Ingo Heinrich

Department of Geosciences, Geography, University of Fribourg, 1700 Fribourg, Switzerland

Tree-ring proxy data from subtropical to tropical Australasia are valuable though rare sources for climate reconstructions. Toona ciliata M. Roem. occurring naturally in this region is among the most promising tree species for future tropical tree-ring research. New increment core samples of T. ciliata collected in the Australian tropics and subtropics exhibited difficult tree-ring structures. During tree-ring analysis two growth anomalies (extensive zones of narrow and indistinct rings) and three types of false rings were discovered which complicated crossdating. Furthermore, little is known about the species’ phenological behaviour and the influence of environmental conditions on intra-seasonal growth and wood anatomical properties. This necessitated a closer examination of the wood anatomy, possible false rings and the species’ crossdating capacity. Hence, growth experiments were conducted on young trees to investigate their responses to different treatments and whether false rings could be induced artificially. The results show that phenology and growth were adjusted according to the severity of the treatments. Restricted growth conditions often caused longer leafless periods, shorter flushes of leaves, decreased height and diameter growth increments and partly resulted in more but smaller vessels. Under optimum conditions T. ciliata did not become leafless, had multiple leaf flushes, sustained growth throughout the experiment and did not form a tree-ring boundary. All specimens entering leafless or at least semi-leafless periods formed one tree-ring boundary during the experiment. The growth reaction was more distinct in the latewood than in the earlywood, in extreme cases suppressing the latewood totally. Only one type of false ring could be induced artificially by totally defoliating young trees. It was possible to alter their phenological performance by artificially changing the environmental conditions. Visual crossdating of samples originating from northeast Australia was feasible within and between trees. For selected years a positive relationship between ring width and precipitation data was found. Although the experiment was conducted on young trees and hence might not be simply generalised and applied to adult specimens the results suggest that the species is well suited for reliable dendroclimatological investigations.

Virtual microscopy applied to wood anatomy

Benoit Jourez (1), Michel Herin (2), Jacques Hebert (3),

(1) Direction de Technologie du Bois, Centre de Recherches de la Nature, des Forêts et du Bois, Ministère de la Région wallonne, Avenue Maréchal Juin 23, 5030 Gembloux
(2) Laboratoire cellules et tissus, Département d'Histologie-Embryologie, Faculté de Médecine, Facultés Universitaires Notre-Dame de la Paix, Rue de Bruxelles 61, 5000 Namur
(3) Unité de Gestion des Ressources forestières et des Milieux naturels, Faculté universitaire des Sciences agronomiques, Passage des Déportés 2, 5030 Gembloux

Objective of virtual microscopy
A preparation is first digitised with a special tool that combines a microscope and a digital camera. The image of the digitised preparation can be instantaneously displayed on a screen with a chosen magnification. Actually, the digitisation concerns several levels of magnification and produces a multitude of tiles that a viewer software collects and displays according to the zone selected by the user.

Opportunities
Located on a server, these images can be shared by several users simultaneously (students during practical work or scientists working in distinct laboratories) located in the same site or in different sites and using, in this case, an Internet access. The classical tools for image analysis provide additional advantages compared to conventional microscopy.

Principles applied to wood anatomy
The project in progress deals with main temperate species in our region. About thirty species were selected. The Research Centre for Nature, Forests and Wood (Gembloux) carried out cuts of 12 m thickness according to 3 ligneous plans. The Laboratory of Cells and Tissue of the Faculty of Medicine of Namur University takes care of the digitisation of the cuts.

Illustration
The attached print screen shows a transverse section in a sample of oak. The software offers various tools: zoom, window of navigation, magnifying glass, measurement...

Additional information
Virtual microscopy applied to wood anatomy will be revealed to the general public on the occasion of the exposition "Knock on Wood" organised by the museum of Central Africa in May 2007. The visitors will be able to handle the images at their disposal.

Growth/climate response along the Carpathian arc

Ryszrad J. Kaczka (1) and Ulf Büntgen (2)

(1) Faculty of Earth Science, University of Silesia, Poland
(2) Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland

Besides the European Alps, the Carpathian arc, with a dimension of ~190 000 km 2, describes the largest mountain system of the continent (45-50 oN and 17-27 oE). The mountain range is characterized by several independent sub-regions providing elevations above 1500 m asl. Highest peaks >2500 m asl are located in the north-western Tatra Mts. and in the most southern part of the range. Widespread forest stands reaching from the montane to sub-alpine zone are typical landscape elements, with climate-driven treeline ecotones, herein predominantly triggered by thermal summer conditions, being situated in an altitudinal belt of 1500-1900 m asl. Here we compile a high-elevation network of tree-ring width data, collected at six sites along a north-south gradient of ~1000 km. The network includes ring width measurements from near timberline forest stands situated in the Beskids Mts., Tatra Mts. (both Poland), Chernogora Mts. (Ukraine), Cahlua Mts., Transilvanian Alps and Retezat Mts. (Romania). The dominant species considered is Norway spruce [Picea abies (L.) Karst.]. Average number of core samples collected per site is 60, with individual chronology lengths ranging from 123-300 years after truncation <5 series. Chronologies are developed on a site-by-site basis using standard techniques, and analyzed to assess local growth/climate response patterns. The six records reveal common inter-annual to multi-decadal scale variability, with a significant (p=0.05) June-July summer temperature signal preserved. Monthly correlations with temperature means of the previous year, and precipitation sums of the previous and current growth year remain insignificant. Spatially coherent pointer years, e.g., annual growth depressions in 1815 and 1912/3 are defined and compared with the timing of summer cooling affects due to the radiative forcing of volcanic eruptions. Longer-term growth variations mimic the transition from the Little Ice Age towards the 20th century warming. Lowest growth rates are described during the Dalton solar minimum in the early 19th century, followed by an increase with slight depressions in the 1910-20s, and 70-80s, and highest productivity within the last decade.

13CO2 pulse-labeling of photoassimilates reveals carbon allocation within and between tree rings.

Akira Kagawa (1), Atsuko Sugimoto (2), Trofim C. Maximov (3)

(1) Wood Anatomy and Quality Laboratory, Forestry and Forest Products Research Institute, Tsukuba Norin P.O.Box 16, Ibaraki 305-8687, Japan
(2) Division of Geoscience, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan
(3) Institute for Biological Problems of Cryolithozone, Yakutsk, Russia.

In order to reconstruct past climate or to study tree growth response to expected climate change, tree-ring parameters such as ring width, density or stable isotope ratios have been used by many investigators. However, more knowledge on the physiological background of dendroclimatology is needed for improved quality of climate reconstruction. For example, autocorrelation is often observed in dendroclimatological research and potentially interferes with climate reconstruction. Proposed causes for autocorrelation are stored carbohydrates, climate effects on formation of buds, leaves, roots, and fruits, or hormones. Clarifying how much photosynthate in the previous year(s) is stored and then remobilized for current year’s tree ring formation will improve our interpretation of dendroclimatological data. Such potential problem is also pointed out in isotope dendroclimatological research. Farquhar model explains carbon isotope fractionation relatively successfully at leaf level, but it excludes downstream fractionation processes such as storage and remobilization of sugar and starch. For example, the model can not fully explain intra-annual δ 13C variation of ring-porous oak wood (Helle & Schleser 2004). Photosynthates assimilated close to the end of growing season can be stored and then remobilized for next year’s earlywood formation. For example, high correlation is reported between earlywood δ 13C values and latewood ones of the previous year in ring-porous English oak (Robertson et al. 1997). In order to apply tree physiological knowledge on carbon allocation to better interpret dendrochronological data such as autocorrelation of tree ring parameters, we need to study long-term carbon allocation with longer chase period up to a few years. We applied 13CO2 pulse-labeling method developed for studying the use of photosynthates for wood formation (Kagawa et al. 2005) to deciduous Siberian trees, in order to study seasonal course of translocation, storage and remobilization of photosynthates (Kagawa et al. 2006b) and time lag in its use for tree-ring formation (Kagawa et al. 2006a). We pulse-labeled 12 saplings of Larix gmelinii (Rupr.) Rupr. at the beginning (June), middle (July), and end (Augusut) of the growing season with the 13CO2. We enclosed the whole tree into a pulse-labeling chamber and later sampled the trees with chase periods from 3 days up to 3 years. Carbon allocation of 13C-labeled photosynthates to different body parts: leaves, branches, phloem & xylem of stem and roots were examined. Acid-soluble starch was extracted from each body part to study carbon turnover of storage material. High-resolution δ 13C analysis of the tre e ring formed was conducted by using a rotary microtome at 30 μm resolution. The spring (June) photosynthates were mainly allocated to aboveground part (over 92 %) and were used relatively quickly for earlywood formation. Relatively more summer (July) and autumn (August) photosynthates were allocated to belowground part (32-44% and 12-24%, respectively) and were used for following year’s tree ring formation. About 60% of labeled carbon in stored starch was replaced every year. Compression wood showed higher δ 13C values compared to normal wood, probably because compression wood is a strong sink of carbohydrates.

References
Helle G. & Schleser G.H. (2004) Beyond CO 2-fixation by Rubisco - an interpretation of 13C/ 12C variations in tree rings from novel intra-seasonal studies on broad-leaf trees. Plant, Cell & Environment, 27, 367-380.
Kagawa, A., Sugimoto, A., Yamashita, K., Abe, H. (2005) Temporal photosynthetic carbon isotope signatures revealed in a tree ring through 13CO 2 pulse-labeling. Plant, Cell & Environment. 28, 906-915.
Kagawa, A., Sugimoto, A., Maximov, T.C. (2006a) 13CO 2 pulse-labeling of photoassimilates reveals carbon allocation within and between tree rings. Plant, Cell & Environment (in press).
Kagawa, A., Sugimoto, A., Maximov, T.C. (2006b) Seasonal course of translocation, storage, and remobilization of 13C pulse-labeled photoassimilate in naturally growing Larix gmelinii saplings. New Phytologist (in review).
Robertson I., Switsur V.R., Carter A.H.C., Barker A.C., Waterhouse J.S., Briffa K.R. & Jones P.D. (1997) Signal strength and climate relationships in 13C/ 12C ratios of tree ring cellulose from oak in east England. Journal of Geophysical Research, 102, 19507-19516.


Changes in species composition of historical timber from the Šumava Region, Czech Republic  

Tomáš Kolář

Department of Botany, Faculty of Biological Sciences, University of South Bohemia

The study was focused on the changes in species composition of timber, which were used for constructions of historic buildings, during last six centuries. Studied area (the Šumava Mountains and the Šumava foothills) was divided into three zones in accordance with several studies from this region, which were carried out on recent specimens. Three zones (<700 m a.s.l., 700–1,000 m a.s.l., >1,000 m a.s.l.), from which local chronologies have similar characteristics, were distinguished in the Šumava Mountains. Tree-ring series from intermediate altitude (700–1,000 m a.s.l.) are the least similar. In high altitudes, not enough historic buildings were found; this study compared only timber from low and intermediate altitudes. Oak, spruce and fir timber was found in historic buildings from both zones, also pine timber was localized in roofs of historic buildings from low altitudes. Dating of spruce samples from intermediate altitudes was found out to be very difficult in accordance with studies on recent material. Only 21 spruce samples (18.9%) from intermediate altitudes were successfully dated – in comparison with 80% of spruce samples from low altitudes. Changes in species composition of historic timber from intermediate altitudes, where 84% of all samples were spruce samples, couldn't be described for this reason. In most cases, timber of all species from low altitudes could be successfully dated. Fir and spruce were dominant species that were harvested during the 15 th and 16 th century. Substitution of fir timber get in the 17 th century and was supplied by pine timber from the end of the 17 th to the beginning of the 19 th century when pine is the dominant tree species that was harvested for timber. During the 19 th century the quantity of spruce timber get larger and became the most common timber at the end of the 19 th century in accordance with changes in forest management. Mean sensitivity of spruce samples from both altitudinal zones was also compared. The results are very close to the results of studies that were carried out on recent material. The spruce timber samples from intermediate altitudes had significantly lower mean sensitivity than the samples from low altitudes. It is caused by the spruce climatic optimum in intermediate altitudes. Also spruce timber from low altitudes that were harvested in the 18 th and 19 th century had higher sensitivity than timber samples from intermediate altitudes. It shows that timber of historical constructions was harvested in low altitudes and was not probably transported from intermediate altitudes.

Pointer years in spruce and fir in Mazury Lakeland

Marcin Koprowski, Mariusz Gławenda

Laboratory of Dendrochronology, Institute of Ecology and Environment Protection, Nicolaus Copernicus University, Gagarina Street 9, 87-100 Torun, Poland

Spruce and fir are native tree species in the Polish flora. In the Mazury Lakeland, spruce is within its natural range, but fir, naturally distributed in southern Poland, was introduced into northern Poland as a result of forest management. Comparison of the two species negative pointer years revealed different reactions to extreme climatic conditions.
A research sites were established in the Wichrowo forest district, samples were taken with an increment borer and measured to 0,01mm. Pointer years were calculated using the WEISER program (Gonzales, 2001) and verified visually. The PRECON program was used for dendroclimatological analysis (Fritts 1996).
A typical pointer year for fir is 1956 and for spruce, 1992. What happened in these two years? Why did one species react while the other did not? Analysis of climatic records reveals a sudden, strong temperature decrease in February 1956; while from May to August in 1992 there was low total precipitation. Additional analysis of pointer years and response function suggests that fir is less sensitive to summer drought, while spruce is more resistant to sharp winter frosts.

Dynamics of pine radial increment under the impact of air pollution in Forest and Steppe zones of Ukraine

Iryna Koval

Laboratory of Forest Ecology, Ukrainian Research Institute of Forestry and Forest Melioration

The analysis of radial increment of trees with accounting both for air pollution load and weather conditions is one of growing points in dendrochronology. The objects of the research were pure pine artificial stands at age of 65-70 years. The density of stocking was 0,41-0,73 (forest zone) and 0,63-0,97 (steppe zone). The type of forest habitat conditions according to Ukrainian classification system was C 2 (relatively fertile, moist) in forest zone and B 2 (relatively poor, moist) in steppe zone.
The basic method of the research was comparative-ecological. Pine stands were studied in different natural zones (forest and steppe), within each stand – on ecological profiles, where experimental plots were established at different distances from the source of emissions in direction of prevailing wind. The data were processed by the International Tree-Ring Data Bank Program. The quality of ring measurements was controlled by the program COFECHA by cross-dating between measurement series. The chronologies STANDART, RESIDUAL, ARSTAN were calculated by the program ARSTAN.
Statistical processing of the data was accomplished as well as correlation and regression analysis of relations of radial increment with climatic conditions and the amount of emissions. Climatic indices for different parts of vegetation period and hydrological year were used in correlation analysis. The relations between the indices of radial increment and hydro-temperature indices such as Bitvinskas’s indices О 1 and О 3, aridity indices , Lang’s pluvio-factors were estimated by the program ITRDB ARI etc.
The changes in formation of annual rings of Pinus sylvestris L. caused by the emissions of air pollutants were analysed in forest zone (factory for production of nitrogenous fertilisers in Rivne) and in steppe zone (industrial agglomeration Lisichansk-Pubezhnoe-Severodonetsk). The absolute values of annual rings’ width were bigger in pine trees in forest zone as compared with trees from steppe zone. The influence of weather conditions of the current year together with three previous years on radial increment was found in Polissya while in steppe zone weather conditions of the current year have main effect on radial increment.
The dynamics of pine radial increment is caused by pollution of forest ecosystems and by droughts in steppe conditions. In forest zone the droughts concurred with the pollutants in decreasing pine radial increment, but the most evident and synchronous reduction of radial increment in the area of intensive pollution was observed in years with the raise of chemical “aggression” of toxicant agents that was amplified by maximum sum of precipitation and high air humidity.
The early wood responds substantially on climatic indices of previous year and those of first half of vegetation period of the current year (mainly, temperature), while the late wood responds on climatic factors of the current year (mainly, precipitation) within the time of this wood formation.
The influence of air pollution is evident in the process of increasing the percentage of late wood with maturing in pine stands in steppe zone. The decrease of pine radial increment occurred together with the increase of the percentage of late wood in conditions of the intensification of air pollution.
The correlation between the indices of pine radial increment and the amounts of the pollutants’ emission is strong and was described by third degree equalization in forest zone, where the source of air pollution is local. The correlation between the same parameters is medium in steppe zone, where sample plots are located near several industrial cities. The correlation between the indices of radial increment and the climatic parameters is low to medium in both zones. More close relations were found between the indices of radial increment and temperature in forest zone, and between these indices and precipitation in steppe zone. In general, the impact of air pollution strengthens the relations between radial increment and climatic parameters.

Dendroecological research of inter- and intra-annual wood-anatomical features in recent and subfossil oaks in Central Europe

Alexander Land (1), Michael Friedrich (1), Ute Sass-Klaassen (2)

(1) Institute of Botany, University of Hohenheim, Germany
(2) Forest Ecology and Forest Management, Wageningen University, Netherlands

During the last decennia more extreme weather events such as high-magnitude floods, like in 1999, and hot and dry summers, like in 2003, in combination with mild and wet winters occurred in Central Europe. These weather extremes caused considerable stress on forest ecosystems. Up to now, there is a lack of knowledge on the effect of the expected climate/weather changes on the growth and vitality of different tree species. European oak (Quercus robur,Q. petraea ) is an economically and ecologically important tree species in Central Europe. Oak has a wide ecological amplitude and grows under various site conditions such as floodplain forest but also on dry sites.
In our poster the outline of a project is presented. The plan is to study the susceptibility of oak growing under different site conditions to changing weather conditions whereby special focus is laid on oaks from floodplain forests. By using classical dendrochronological and new wood anatomical variables we will try to assess climate-growth relationship with a high temporal resolution. Specific wood anatomical features are linked to environmental impacts. The study material comprises 80-100 year old oaks from temporary wet floodplain forests along the river Main. In drought, flooding and defoliation experiments are performed on young potted oaks. The results of the study on recent floodplain oaks and the experiments are carried over to wood-anatomical features measured on subfossil oaks from former floodplain forests to enable the reconstruction of extreme climate and weather events for parts of the Holocene.

Subfossil pine wood and wooden trackways in the Campemoor (Lower Saxony, Germany) – dendrecological evaluations in context with the history of peatlands and climate change

Hanns Hubert Leuschner (1), Andreas Bauerochse (2) & Barbara Leuschner (3)

(1) Labor für Dendrochronologie u. Dendroklimatologie, Universität Göttingen, Von-Siebold-Str. 3a, D-37075 Göttingen, Germany
(2) Niedersächsisches Landesamt für Denkmalpflege, Scharnhorststr. 1, D-30175 Hannover, Germany
(3) Dendrochronologisches Labor Göttingen, Rosdorfer Weg 10, D-37073 Göttingen, Germany

Most of the raised bogs in Germany are situated in the Lower Saxony part of the North German Lowlands, in a landscape that was moulded during the ice age. In many of these peatlands within the peat, at the base of the raised bog peat, a subfossil wood layer of pine (Pinus sylvestris) exists. In the Dümmer Geestniederung, one of the most important early settlement areas in northwest Germany, in the Campemoor these layers have been palynologically and dendroecologically investigated.
The dendroecological correlation of the frequency, germination and dying-off of these trees with those of the subfossil oak trunks from Lower Saxony shows the change of the ecological conditions in a large time scale. As a result of these investigations the transition from a drier to a more humid climate period that initiated the raised bog growth happened in two phases at the beginning of the 3 rd millennium, interrupted by a drier period between 2825 – 2770 BC. Afterwards large areas of former settlement sites within today´s Campemoor became inaccessible and were covered by raised bogs.

The impact of climate change on forest growth trends in Komi Republic ( Northwestern Russia): combination of dendrochronological data and remote sensing analysis

Eugene Lopatin (1,2), Taneli Kolström (2), Heinrich Spiecker (3)

(1) Institute of Biology, Komi Science Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
(2) University of Joensuu, Mekrijärvi Research Station, Joensuu, Finland
(3) Albert-Ludwigs-Universität Freiburg, Institute for Forest Growth , Freiburg, Germany

To adopt forest management practices to changing environment, it is important to understand the response of unmanaged natural forest to changing climate changes. Komi Republic is the region of geographical Europe where the largest areas of natural forests still exist. Analysis of climate data for the last century showed that there is a clear long-term climate change trend. During the last 20 years, the temperature increased in most of the meteor ological stations for the last during and 40 years ago and precipitations began to increase. Growing season extended in the region. This increase has resulted in accelerated tree growth across the Komi Republic and changes in of site productivity.
Discs, cores and model trees were c ollected in 4 forest zones of Komi Republic: south taiga sub zone, middle taiga sub zone, northern taiga sub zone, forest-tundra transition zone. Mature dominant trees without visible signs of damage were randomly selected as sample trees (126 trees of Siberian spruce and 85 trees of Scots pine). Chron ologies covering the period from 1774 to 2003 for Siberian spruce and from 1786 to 2003 for Scots pine were built for each forest zone. Dendroclimatic analysis was used to identify those climatic factors that influence high frequency variation in the radial growth of Siberian spruce and Scots pine. The total variance is explained by temperature varied change from 14% to 48% and precipitation from 10% to 58%. The significant climatic parameters for radial increment in Komi Republic were identified, but the response to climate parameters changes over the time.
The vegetation ev olution in the Komi Republic (Northwestern Russia) was analyzed from 1982 to 2001 using calibrated NDVI temporal series ( Pathfinder Land dataset) from NOAA-AVHRR images. A statistically significant correlation between NDVI data and tree ring width has been identified for the territory of Komi Republic ( Northwestern Russia). The increased site productivity caused increase rise in integrated NDVI values from June to August. This allows using NDVI as a proxy for estimation of forest growth trends for the last decades. A positive and significant trend in NDVI data has been identified from 1982 to 2001 coinciding with a site productivity increase in the study area. The distribution of the trends in NDVI data changes in Komi Republic on from south-west to north-east gradient. NDVI data could be used to increase spatial res olution of tree ring width series.

The study was financially supported by the INTAS fellowship grant 04-83-2209, INTAS infrastructure grant 03-70-618 and NorFA grant “Network for Dendrochronological Research in Northern Europe”.

Dendroecological study of Pinus sylvestris growing on a bog lake island in Latvia

Iluta Lūce

Faculty of Biology, University of Latvia, Kronvalda bulv. 4, Riga LV – 1586, Latvia

The study was conducted in Cena Mire, a large with the total area of 2133 ha located in the Coastal Lowland of Latvia. Cena Mire is included in the list of protected nature areas of Latvia, and is an Internationally Important Bird Area. However, the area has been affected along its border by extensive peat extraction, which began in the 1930’s. Presently, very little is known about the effect of the drainage for peat removal on the natural ecosystems. At the same time, a EU LIFE – Nature project is underway to block the water flow in the drainage ditches to raise the water levels.
Scot’s pine growing in the mire may offer a retrospective picture of the past fluctuation in the hydrological regime on the ecosystem.
Part of the drainage system was established close to a bog lake. The lake contains several islands covered with pine. In a preliminary study, all trees (36) on one island were cored as close as possible to the tree base. The cores were glued into grooves, sanded and scanned. Tree ring widths were measured using LIGNOVISION software.
Tree age on the island reached 202 years. Rapid establishment of pine began 80 years ago, probably as a result of ditching of the mire for peat extraction.
Chronologies were established for the trees over 100 years old, and for trees younger than 80 years. Radial growth was analyzed in relation to climatic and hydrological factors.

Genetics of wood formation in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), response to drought stress events.

Alejandro Martinez Meier, Philippe Rozenberg, Leopoldo Sanchez, Dalla Salda Guillermina, Pastorino Mario.

Institut National de la Recherche Agronomique (INRA), Unite Amelioration Genetique et Physiologie Forestieres, 2163 Avenue de la Pomme de Pin, BP 20619, Ardon 5166, France

Extremely high temperatures were reached in several European countries including France during summer 2003, broking in some cases all-time maximum temperatures. The low precipitation during the same period failed to compensate for the evapotranspiration, creating an accumulative water balance deficit. Many trees were manifestly affected, from partial foliage necrosis to the death of individuals. Douglas-fir (Pseudotsuga menziesii) was one of the most affected species.
During the growing season, cambial activity and characteristics of xylem cells deposited are affected by variation of water balance. Thus genetic variation of characteristics of wood formed in reaction to an extreme climate event like the 2003 heat wave can provide information about tree adaptation. This information can be used in tree breeding programs, for example to help select better-adapted genotypes.
Simple microdensity characteristics of the wood formed during the 2003 growing season were compared among nine Douglas-fir clones installed in three different geographical locations, to the characteristics of rings 2002 and 2004, formed during normal years from the climatic point of view.
Our results show that: (1) the heatwave impacted more one site than the other two, (2) in this site, all characteristics of the ring 2003 that we studied were significantly affected by the 2003 heat wave: the values of all ring variables except one significantly decreased from 2002 to 2003 (ring width, ring mean density, ring maximum density and within-ring density standard deviation). Only minimum ring density significantly increased from 2002 to 2003. On the contrary, the values of all ring variables but one (ring minimum density, which significantly decreased) significantly increased from 2003 to 2004. (3) The reaction of Douglas-fir to the 2003 heat wave and the 2004 recovery was described using between-successive-year differences for the ring variables. The results show that there is significant genetic control of tree reaction for all ring variables, except for ring maximum density between 2002 and 2003.

2003 – where is the negative pointer year? A case study for West Germany

Burkhard Neuwirth und Marc Hennen

University of Bonn, Department of Geography, Meckenheimer Allee 166, 53115 Bonn, Germany

Since the beginning of meteorological data measuring the summer of ad2003 was one of the warmest. In this extreme summer positive temperature anomalies from July to September corresponding with a long period of missing rainfall lead to extraordinary dryness stress situations for plants.
From the biological point of view trees react to extreme dry weather conditions by closing their stomata and accordingly by reducing their physiological activities. As a consequence trees built a narrow tree ring such as in the very warm and dry year ad1976. But in 2003 there were no negative growth reactions in the tree-ring widths of West German deciduous trees.
What is the matter?
The presented poster gives answers.
For this study pointer years since ad1901 for more than 300 dominant and subdominant beech (Fagus sylvatica) and oak (Quercus petraea) trees were investigated. The trees are distributed over 20 sites representing the site ecological spectrum of West German forests and are located in the Eifel mountains.

Age and spatial structure of a wet old growth Pinus sylvestris forest in Latvia

Zanna Osmane, Guntis Brumelis

Faculty of Biology, University of Latvia, Kronvalda bulv. 4, Riga LV1586, Latvia

Seržu mire was recently found to support the oldest known Pinus sylvestris trees in Latvia. The area is part of a Nature Reserve, established mainly due to its importance as a capercaillie Tetrao urogallus lekking area. As required in habitat selection for this bird species, the forest stand is fairly open, with an uneven structure. The forest raised the attention forest ecologists, as it appeared visually to lack the common pulse establishment by cohorts for pine, and since there was no evidence of fire scars on the older trees. The study was initiated to determine the past establishment of the stand by aging the trees.
20m*20m plots were set up in diffferent parts of the mire. All trees were cored as close as possible to the base. Tree diameter at breast height and position in the plots were measured. Cores were glued in grooved boards and sanded. Tree rings were measured using the Lignovision program.
The age structure of trees in the mire supported the hypothesis of continuous establishment of seedlings. However, seedlings in the mire are rare and spatially, and the ground cover and understorey (feather moss, Sphagnum, ericaceous shrubs) are known to hinder establishment. As it is well known that Pinus sylverstris requires disturbance to initiate a new cohort, further study will aim to determine the factors supporting seedling establishment in the mire.

Dendroecological study of Beech (Fagus sylvatica L.) and pedunculate Oak (Quercus robur L.) in Belgium

Valérie Penninckx

The poster highlights the specific methods of ring measurement and standardization we used and answers some of the main questions of the study: (1) What are the major climatic influences on the growth of these two species in Belgium? (2) May on of these species be used as an efficient bioindicator of Belgian forest environment evolution?
The strength of the study lies in the comparison of the two species in a (Belgian-) wide range of ecological conditions.

1876 - a structural pointer year for Eastern Carpathians

Ionel Popa (1), Zoltán Kern (2)

(1) Forest Research and Management Institute, Research Station for Norway Spruce Silviculture, C âmpulung Moldovenesc, Romania
(2) Eötvös Loránd University, Department of Physical Geography, Department of Paleontology, Pázmány Péter sétány 1/c, 1117

The width of the tree’s annual ring varies from one year to another in a manner more or less regular, most of this variability being due to the past and current particular climatic conditions of the growth period. Extreme climatic condition generates extreme response from tree, mostly on structural plan. This poster presents the effect of a freezing day in the year 1876 on the Eastern Carpathians. Analyzing the dendrochronological series for coniferous species from different mountainous areas ( Eastern Carpathians) in the year 1876 we have a significant reduction of growth and this can be interpreted as pointer year. A detailed analysis of the structure of this ring put in evidence a structural modification characteristic for a frost ring. This structural aspect was identified at the majority of trees and at all coniferous species (spruce, fir, stone pine, mountain pine, larch) from Eastern Carpathians. Reviewing the documentary sources we have found transactions about heavy frost event from the year of 1876. According to historical documents there was a widespread frost in the Carpathian Basin at 19-20-21 of May, 1876, and this event is the only mentioned frost event from the vegetation period of the year. The above average temperatures in April could enhance the cessation of winter dormancy and accelerate the initiation of growing season, however the subsequent May was much severe than the average so the saturated juvenile cells suffered frost lesion.
This year through him particularly anatomical structure and growth reduction is a structural pointer year for Eastern Carpathians with great valence in crossdating.

The influence of wood ants on the forest trees growth

Michal Rybníček (1), Jan Frouz (2), Vladimír Gryc (1), Hanuš Vavrčík (1), Ondřej Štourač (1)

(1) Mendel University of Agriculture and Forestry Brno, Faculty of Forestry and Wood Technology, Department of Wood Science, Zemědělská 3, 613 00 Brno, Czech Republic
(2) Institute of Soil Biology, Biological Centre Academy of Science of the Czech Republic, Na Sádkách 7, 370 05, České Budějovice

Influence of wood ant (Formica polyctena, Foerster) on growth of spruce (Picea abies (L.) Karst.) was studied in Central Bohemia. The ants (Formicidae) represent a frequent member of forest ecosystems they are important predators, support aphid population and honeydew production, and have significant impact on physical, chemical and biological properties of soil. Here we explored affects of ants activity on the soil and forest tree growth using soil analysis and tree-ring analysis. Our research showed that the activity of ants shifts the pH of soil towards the neutral value and increases content of some nutrients in soil (P, K, N). The tree-ring analysis reveals that trees located directly in the ant nest or in the immediate vicinity (within 1 m from the nest) have higher increment of tree-ring widths than trees located in a distance from 5 to 50 m from the nest. However the trees within 1 m from the ant nest have lower increment of tree-ring widths than trees growing on control stands without presence of wood ants (about 300 m from closest nest). This indicates complex effects of ants on tree growth.
The project was financially supported by the research plan of LDF MZLU in Brno, MSM 6215648902 and the CR Grant Agency 526/03/H036.



Is wood analysis a useful tool for studying growth respiration in tree stems?

An Saveyn, Kathy Steppe and Raoul Lemeur

Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium

Interest in stem respiration is increasing as many quantitative estimates show that it is a large component of the annual carbon balance of forest ecosystems. Although the biochemical pathways are similar, stem respiration is generally separated into two components: maintenance respiration, which maintains existing living cells, and growth respiration, which provides the energy needed to synthesize new tissues. Growth respiration is supposed to be a function of diameter growth, which is usually measured with band-dendrometers or linear variable displacement transducers. However, several studies showed that peak of CO 2 emission by stems is much later in the growing season than maximum diameter growth. Diameter growth mainly reflects cell expansion. Cell expansion is a physical process requiring little chemical energy. The greatest energy requiring process is the incorporation of carbon skeletons into new cell structures. Unfortunately, this process can not be simply measured with a sensor. Therefore, this abstract aims at opening a new ground for discussion on the possibilities of wood analysis for growth respiration studies.

GWL-Fingerprints in Central European Tree Rings

Johannes Schultz, Burkhard Neuwirth, Jörg Löffler

University of Bonn, Department of Geography, Meckenheimer Allee 166, 53115 Bonn, Germany.

The large-scale weather situations (Großwetterlagen, GWL) are the pre-dominant factors for the meteorological and climatological conditions in Central Europe. The main target is to detect the signals of European large-scale weather situations in tree rings.
Further more we are interested in the changes of circulation. Especially since the late-sixties the frequency and persistence of European large-scale weather situations with southerly flows over Central Europe have increased. In contrast, large-scale weather situations with northerly flows have decreased.
Due to the fact that climate is the major forcing factor influencing tree ring growth these changes in circulation and persistence of the GWL ought to be proved by dendroclimatogical investigations.
The connection between tree-ring growth and GWL will be analysed by a dendroclimatological network basing on the data bank software ORACLE. The dendrochronological part of the network includes ring-width data from more than 500 Central European sites. Within this project all important Central Europe forest-tree species will be investigated (Abies alba, Fagus sylvatica, Larix decidua, Pinus cembra, Pinus uncinata, Picea abies, Quercus petrea, Quercus robur).
The conceptional approach of this new project as well as the dendrochronological and climatological databases will be presented on our poster.

Will a mechanistic model for radial stem growth make it in dendroecology?

Kathy Steppe and Raoul Lemeur

Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium

Radial stem growth reflects the conditions in which a tree is growing. Eco-physiological disturbances on tree growth can be tracked down by studying the changes in radial stem growth. Radial stem growth dynamics can be monitored by taking micro-cores at regular time steps of the outermost tree rings of naturally grown trees in the field and newly formed cell layers can be counted and measured. Less labour-intensive is the application of linear variable displacement transducers (LVDTs) for a continuous detection of radial variations of the stem. However, the LVDT-signal consists of several components of which the radial stem growth and the water-related shrinkage and swelling of the bark are the most important ones. Hence, mechanistic modelling is necessary to separate the measured stem diameter variations into radial stem growth and water-related fluctuations. Based on tree-water relations, we were able to develop a first part of this comprehensive mechanistic model. The second step is to extent the model for structural stem growth (i.e., the incorporation of carbon skeletons in new cell structures). Because there still is a missing link between tree physiological and wood anatomical knowledge it remains difficult to mechanistically model structural stem growth and predict radial growth of individual trees from climate. Therefore, this abstract aims at opening new ground for discussion on possible mechanisms for radial stem growth.

How do stable isotopes react on Larch Budmoth Outbreaks?

Kathrin Weidner (1,2), G. Helle (2), J. Löffler (1), B. Neuwirth (1), G. H. Schleser (2)

(1) Department of Geography, University of Bonn, Meckenheimer Allee 166, Germany
(2) Research Centre Jülich GmbH, Department of Chemistry and Dynamics of the Geosphere, ICG-V: Sedimentary Systems , Germany

European Larch ( Larix decidua Mill.) from the subalpine forest is commonly used for low-frequency temperature reconstructions (Büntgen et al., 2005). These subalpine forests form the habitat of the larch budmoth (LBM; Zeiraphera diniana Gn). A strongly increase of the population of this insect at intervals of 7-11 years leads to a typical tree-ring pattern, which is characterized by an abrupt growth reduction in the year of the outbreak and a slow increase of ring width in the following years. This typical tree-ring pattern causes problems in high-frequency climate reconstructions. The aim of this study was to investigate to what extent LBM outbreaks modify the signature of the stable carbon and oxygen isotopes of the corresponding tree-rings. The inter-annual and intra-annual carbon and oxygen isotope analyses bear more information on the mechanisms which are responsible for the observed pattern. Cores of two sites on the south-exposed slope at 2000 m and 1700 m a.s.l. in the Lötschental/Switzerland are prepared to investigate the reaction on LBM outbreaks of different intensities.

Tree rings chemical content fluctuations between acid and calcareous soils of Fagus sylvatica L stands measured by microanalysis.

Anny Weitner, J.L. Dupouey, R. Bailly, C. Rose

UMR Forest Ecology and Ecophysiology , Phytoecology team, INRA-NANCY, France

Differences in mineral nutrients content in beech (Fagus sylvatica L.) tree rings in the HNE network (Beech stands of north-eastern France) have been evaluated on two soils types. Six stands are located on acids soils and six others are located on calcareous soils. Three dominant trees have been cored in each stand. The chemical measurements have been made in the earlywood (12 stands, 3 trees by stand, one core per tree and two periods by core corresponding to ten rings in heartwood and ten rings in sapwood). The microanalysis of mineral nutrients concentration in tree rings have been measured with an energy dispersive spectrometer (EDS) coupled with a low vacuum scanning electron microscope.
We found differences between calcareous and acid stands in tree rings element concentration. Calcareous stands have typically high calcium and low manganese concentration in tree rings in comparison to acid stands. These differences are mostly representative of the nutrient richness of the soil and especially saturation rate and soil upper horizon pH. We also undertook to measure element concentration in the bark. It appears that differences in elements concentrations are greater when considering the bark compared to the wood. These results point out the ability of SEM/EDS method to measure differences in two soils type differing in acidity status. We showed that tree nutrient status is reflected in wood and to a better extend when considering the bark only. Bark seems to have a high potential to be used as a tree nutritional status diagnostic.



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