Age and growth rate relationships: Are young trees growing faster than their predecessors?

Marc D. Abrams, Sarah E. Johnson
School of Forest Resources, Penn State University, 307 Forest Resources Building,University Park, USA

    We hypothesize that individual trees within a species approach maximum longevity by growing very slowly throughout most or all of their life. Within that framework, species longevity, and thus growth rate, will vary by shade tolerance and site quality. This study utilizes data from the International Tree Ring Data Bank website and tree cores collected in the field to explore the relationships between growth rate (basal area increment; BAI) and age class (from young to old) for seven contrasting eastern tree species in the eastern U.S. Our results support the hypothesis that older trees within each species have very slow growth and that growth rate and longevity varies inversely with shade tolerance between species and with site inferiority. Almost all trees exhibit increasing basal area increment with increasing age (i.e., from past to present), even among the oldest individuals. In addition, we found that younger trees (< 50-100 years of age) within each species are consistently growing faster than the older trees did at the same age. This suggests that global change phenonmenon, such as land-use changes, global warming, and precipitation chemistry (nitrogen input) has increased the growth rate of trees during the last half-century or more in the eastern U.S.


Blue Reflectance – Method and First Results

F. Babst¹, D. Frank², U. Büntgen², D. Nievergelt², J. Esper^2
1Department of Environmental Sciences, University of Basel, Basel, Switzerland, fbabst@gmx.ch
²Swiss Federal Research Institute WSL, Birmensdorf, Switzerland

    Blue reflectance is a relatively new approach which aims to substitute the cost-intensive and time consuming standard method to measure maximum latewood density (MXD). This experimental technique is based on reflected instead of transmitted light (using x-ray films) and can therefore be accomplished with a common flatbed scanner and adequate imaging software. The blue channel of an RGB picture is most sensitive for the lignin content of the latewood and therefore most likely resembles the MXD best. The blue reflectance method was tested using a series of 12 high-elevation pine (Pinus uncinata) samples from the Spanish Pyrenees with known maximum latewood density in order to evaluate the ability of the reflected blue light curve to resemble the output of the standard x-ray based method. Attention was paid on the sensitivity of this method to wood and surface preparation, scanning resolution, and other influential parameters. The first results proved to be promising but showed a strong variability of the resulting curve with changing treatment.
In a next step, we produced 30 pine pieces in order to standardize the preparation. Both, the x-ray based method and the experimental blue reflectance method were carried out and the results compared. The outcome shows a significant reciprocal correlation (-0.56 to -0.89) between the two methods. The slope of linear trends however can differ considerably. Based on these preliminary results, further research needs to be carried out producing whole chronologies for different species in order to examine the expression of linear trends, long term shifts, age trends and the influence of different scanner systems.


Autocorrelation and sensitivity in tree ring series – opportunities for biological interpretations

Wolfgang Beck
vTI, Institute for Forest Ecology and Forest Inventory, Eberswalde, Germany

    Autocorrelation and sensitivity are basic parameters of tree ring series which can be calculated quick and easy. Both parameters show a specific informational value. Autocorrelation of first and higher order describes the dependence of the current tree ring width from preceding ring widths. The natural meaning of this statistical parameter is that tree ring widths at each time step are never independent on their own. Current impacts are damped but persist by after-effects. Autocorrelation can be seen as a mathematical expression of the biological inertance of tree growth and may be interpreted as buffering ability of trees against external forces. The ability to buffer prevents trees and forests from immediate suffering and dying off by singular external impacts. It‘s a principle of survival. Sensitivity within tree ring series indicates the year-to-year changings of ring width. It shows if moderate or more extreme environmental factors did affect tree growth. Low sensitivity stands for low fluctuations of environmental factors but high sensitivity must be seen as a clear indicator of stress conditions. Both, autocorrelation and sensitivity can be calculated and applied to entire time series or subranges of these; comparisons of different stands, tree species, age classes, types of stand structure; a number of sample trees inside one stand. Autocorrelation and sensitivity may also be calculated simultaneously for floating subranges within the same time series and may be investigated concerning potential interrelations and their temporal drift.   With the help of a number of beech and spruce chronologies from Germany a simultaneous decrease of autocorrelation and increase of sensitivity was found. It must be interpreted as an increased vulnerability, especially against unfavourable climatic impacts. Compared to other tree species in Germany, beech must be regarded as beeing especially endangered by climate change. Spruce stands outside of their natural elevation range show a quite similar pattern concerning the temporal drift of the autocorrelation–sensitivity relation. Consecutive development stages may be identified. Investigations of such changings can comprise the mean ring width series of chronologies as well as the patterns of a number of single trees within one stand. A number of examples will be shown.


Growth reduction of black pine stands associated with defoliation by the pine processionary moth

Darío Martín-Benito, Miren del Río, Isabel Cañellas
Departamento Sistemas y Recursos Forestales. CIFOR-INIA, Madrid, Spain, dmartin@inia.es

          Around the year 1963, an outbreak of the pine processionary moth (PPM; Thaumetopoea pityocampa) began in the Iberian Mountain Range of eastern Spain. Severe and even total pine defoliation was observed mainly on black pine (Pinus nigra) whereas no damage was observed on P. sylvestris and P. halepensis. According to a report from 1968, this outbreak lasted at least until that year because of the PPM diapause behavior. As part of a research project to study long-term radial growth trends of black pine in Spain, we have observed plots where trees show narrow rings for the years of the outbreak while other plots show normal rings. The objective of this work was to interpret these different patterns and to asses growth reductions caused by PPM. The observed reductions in ring width of the ‘attacked’ plots ranged from 20 to 40 % for the duration of the outbreak as compared to ‘not attacked’ (control) plots. Ring-width decreases were also observed before and after the outbreak but during the outbreak period trees showed the maximum growth reduction for one single year and the longest period of maintained growth reduction. We present these growth decreases in terms of total ring-width, earlywood and latewood and discuss them with climatic variables.


Is it really possible to date old chestnut (Castanea sativa Mill.) timber structures in Italy? A case of study.

¹Mauro Bernabei, ¹Claudio Pollini, ²Nicola Macchioni
¹CNR/IVALSA, S. Michele all'Adige, Trent, Italy, ²CNR/IVALSA, Sesto Fiorentino, Florence, Italy

    The possibility of dating chestnut timber (Castanea sativa Mill.) by means of dendrochronological analysis is very debated. Chestnut is estimated that accounts for 90% of the timbers in historic buildings of central and southern Italy. However, despite the abundance of such material, dendrochronological dating of it is a very problematic topic. First of all, the shortness of the series. Chestnut is cultivated since ancient time as coppice. The high growth rate of chestnut in the Central Italy allows short turnover: around 12 years or less. Consequently a limited number of measurements in the samples is constantly found, even when the pieces of the wooden structure are of large size. The small number of rings impedes significant statistical correlation, so that dating is often of limited reliability. Second: the species has always been subjected to strong human influence. It is sufficient to think that the most part of the chestnut woods in Italy derives from ancient replacement of oak forests by man. Cultivation, for wood or fruits, alters the natural growth rhythms that are the basis for dendrochronological dating. Furthermore, even ancient chestnut timber is prone to this problem. It is in fact a mistake to think that, in Italy, forests grown centuries ago are more “natural” than forests of today. Forestry in Roman times, and perhaps even in the centuries before, was very intensive in that area, and not much different from now. Third: in peninsular Italy, there are no long reference chronologies for the species. The only existing chronology extends for little more than a century and, in general, in central Italy there are no master chronologies for deciduous trees that exceed 5 or 6 centuries. It is therefore very difficult to develop any inter-specific synchronization, such as chestnut with oak. So, what can we do with this species? We have just to consider this material simply not datable or it is worth to try to date with an approach strictly related to the behaviour of the species? Work reported here shows that adapting classical dendrochronological analysis to the specific characteristics of the species it is possible to date an important building structure constructed prevalently in chestnut. The Royal Palace in Naples was the centre and image of power, as well as the seat of the historical events in Naples and the South of Italy for almost four centuries. The Sala Diplomatica, is an anti-chamber of the Throne room and one of the most important rooms in the palace, due to its dimensions and decorations. It is located in the centre of the historic building facade, facing Piazza del Plebiscito, which is considered the main square of Naples. In the wider context of a diagnostic study of the building, dendrochronology permitted dating of the structure as a whole and enabled the design of precise restoration solutions. The limited reliability linked to the small number of rings in chestnut timbers was overcome due to a generally good visual synchronisation of the series. The presence of a long tree ring series of fir in the same structure allows to date the material. In conclusion, it is always worth to approach the wood with mind free from prejudice.


North Atlantic Oscillation signal in pointer years of oak in Poland

Szymon Bijak

    The North Atlantic Oscillation (NAO) is recognised as a driving factor of climate conditions over vast areas of Europe. Two various nodes of NAO, described with positive or negative values of NAO index, correspond to either warmth and dryness or chill and humidity occurring in different parts of the continent. This, in turn, influences directly growth of trees. However the question arises whether this general climate pattern is responsible also for extraordinary growth reactions that can be indicated by pointer years or these phenomena have other reasons The study analyses the relationship between tree growth and NAO pattern on the example of 13 English oak chronologies from different parts of Poland. Special attention was gained to the character of NAO during detected pointer years, especially those occurring on larger part of the country. Obtained results show that NAO has rather slight influence on growth of English oak in Poland. Neither monthly, nor seasonal and annual NAO indices relate to ring widths significantly. No clear relation between the character of NAO and pointer years was found either. It seems that the influence of NAO does not reach that far eastwards and unusual oak increments have rather local than global causes.


Late-glacial fires and water-level increases disturbed a pine forest in Reichwalde, E-Germany

Ilse Boeren^1,2, Michael Friedrich¹, Hans-Peter Stika¹, Maria Knipping¹, Manfred Küppers^1
1Inst. für Botanik (210), Universität Hohenheim, Stuttgart, Germany
²Laboratory for Wood Biology and Xylarium, Royal Museum for Central Africa, Tervuren, Belgium

    A well preserved Late-Glacial pine-birch forest has been excavated in a lignite mine in Reichwalde. The excavation took place in two dried-out peat bogs located at about 300m from each other: Grossteich Altliebel and Neuteich. The advantageous circumstances for the preservation of organic material, inundation and peat-formation, provided more than 1500 subfossil trees in situ, together with the soil they were standing on, their undergrowth and the litter they produced. They cover a period of 860 years in the Bølling-Allerød Interstadial (14100–13300 yrs BP – end of Bølling and first two thirds of Allerød). The dendrochronological dating of stratified pines makes it possible to precisely date the sediments, 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. Different tree-ring parameters indicate that, in the early 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 is confirmed by the better correlation of the Reichwalde chronology with the northern and southern Germany chronologies in the younger 400 years. The fact that most of the trees were found “in situ” and that maps of the trees excavated in Grossteich were drawn by the Landesamt fuer Archaeologie Sachsen, allowed us to reconstruct the stand structure of parts of the forest, over different generation phases during the first 450 years of the chronology. This revealed that most stands had a rather open structure and that the populations existed out of trees of different age. Moreover, the mean age of the pines from Grossteich is not very high (about 85 years) and there is a clear lack of young trees in the population. This means that the pine population has been frequently disturbed. Using precisely dated fire scars found on the trees, we charted an 800-year fire chronology. Frequent fires not only destroyed the undergrowth and the seedling and sapling populations of the pines, but also scarred the older trees. The fires were not very severe; most of these trees have survived and have registered many of them during their lives. The results of the palaeobotanic investigations confirm high frequency and low severity of the fires: bushes were rarely found, and sedges, grasses and other grass-like vegetation dominated the undergrowth. The fires, however, did not account for the periods of very strong die-off in the pine population happening at least three times in the 450 years of tree preservation in Grossteich. During these periods, in parts of the excavation area, almost all the pines died and the tree rings of the surviving trees were discovered to be very narrow or missing. Through the discovery of a surviving tree with a negative geotropic root that started to grow right after a die-off, we could explain that these big and sudden disturbances in the population are caused by periods of strong water-level increase in the area.


Cambium activity and phenology in temperate dicotyledon trees

Anaïs Boura, Elise Tancoigne, Dario De Franceschi

         In mid latitude, there is a strong relationship between plant phenology, especially spring events (budding, leafing, flowering) and some environmental factors especially photoperiod and temperatures. In the same time, it exists a close connection between phenology and cambial activity.  In order to better understand this link, the wood formation and phenology of three dicots trees (Castanea sativa Mill., Fagus sylvatica L. and Corylus avellana L.) with different life cycle (time of flowering, leafing ...) was followed between 2005 and 2007, in two French sites.
In each area, wood from both trunk and newly formed branches were harvested and prepared, and on the same time, phenological data were recorded throughout the growing season. Results obtained from repeated cell analysis showed a relatively short cambial activity period for the three species divided in three step; a slow beginning, followed by a fast growth in the middle of the vegetation period and a decreasing wood formation activity towards the end of the period. No time-lag could be detected between sites whereas differences between species, especially in cambial reactivation were noticed. Indeed, in Castanea sativa the beginning of wood formation is very rapid and occurs simulteanously throughout the entire tree (branches/trunk) a few days prior to bud break. On the contrary, in Fagus sylvatica and Corylus avellana, cambial reactivation seems to begin at the base of the swelling buds and then proceeds downward the base of the tree.  These differences may reflect alternative designs of growth and survival, especially in sap conduction and refilling of vessels after the winter for species with different wood porosity patterns.


Gums and plums: recent progress towards a dendroclimatological network in the Australian Alps

Matthew Brookhouse
Fenner School of Environment and Society, The Australian National University, Australia

    Drought is a familiar and devastating feature of climate in Australia. However, the current drought is exceeding previous records on both the duration and intensity of droughts in Australia and has significantly reduced inflows to major water storages, resulting in shortages in rural and urban areas of the continent. These shortages have significant implications for the agricultural and electricity-generation industries. One question that has emerged is what role climate change and natural variability are playing respectively. To answer this question, governments are increasingly looking to sources of data on pre-instrumental climate. Following previous studies that have shown strong correlations between ring width in subalpine Eucalyptus pauciflora and variables such as soil dryness and river flow, we have commenced the development of a dendroclimatological network within the Australian Alps. To complement the record available from E. pauciflora we have also begun analysis of a longer-lived tree species Podocarpus lawrencei (plum pine). Like Eucalyptus pauciflora, Podocarpus lawrencei appears to be highly sensitive to snow cover and appears, therefore, to hold potential for reconstruction of river flow and records of drought in south-east Australia. Preliminary results from the first chronologies in the network and an outline of future activities will be presented.


Three centuries of Central European drought dynamics

U. Büntgen¹, R. Brázdil², D. Frank,J. Esper^1
1Swiss Federal Research Institute WSL, Birmensdorf, Switzerland, buentgen@wsl.ch
²Institute of Geography, Masaryk University, Brno, Czech Republic

    Tree ring data from Slovakia are used to reconstruct decadal-scale fluctuations of the self-calibrated Palmer Drought Severity Index (scPDSI) over 1744-2006. The ring width chronology correlates at 0.58 with inter-annual and up to 0.88 with decadal-scale variations of Central European (48-50° N and 18-20° E) June-August scPDSI (1901-2002). Driest and wettest spells common to the proxy and target data are 1947, 1948, 1964, and 1916, 1927, 1938, 1941, respectively. The model further preserves decadal swings with dry conditions ~1780-1810, 1850-1870, 1940-1960, and during the late 20th century. The wettest period occurred ~1745-1775. Comparison with nine annual-resolved hydro-climatic reconstructions from Central Europe indicates significant high to low-frequency coherency for most records, including a longer-term drift from initially pluvial to drier climate at the transition of the 18th-19th century. Disagreement between the Slovakian and all other estimates is most evident from 1880-1890. Comparison with European-scale fields of 500 hPa geopotential height reveals stable synoptic patterns of Central European high pressure for the driest summers back to 1744. Low pressure over Western Europe triggers wet conditions in the Carpathian region. Documentary evidence and instrumental measurements further allow characteristic weather conditions of reconstructed scPDSI extremes to be detailed.


Calibrating proxy-climate relationships in central Sweden using stable isotopes in tree rings

Rochelle Campbell, Iain Robertson, Danny McCarroll, Neil Loader, Håkan Grudd, Bjorn Gunnarson
Department of Geography, Swansea University, UK

    The physical and chemical analysis of tree rings provides a method of obtaining climatic information prior to the instrumental period. The various proxy variables used, however, have a number of limitations. In general, the advantages of using carbon isotopes determined on tree-ring cellulose to reconstruct past climates are: i) the factors that control the relative amounts of the stable isotopes are perhaps better understood than those that controlling ring-width and relative density; ii) at less marginal sites, the strength of the common signal is often higher than other proxies; and iii) only minimal detrending of the time-series is believed to be required. Consequently, it may be possible to reconstruct the lower-frequency climatic variations that are often removed when harsh detrending techniques are employed with other proxies and to place statistically defined errors upon the resulting climatic reconstructions. This research presents the relationships between carbon stable isotopes (δ13C), blue intensity and ring widths in absolutely-dated Scot’s pine (Pinus sylvestris L.) tree rings from Mora, southern Sweden with summer air temperature, and precipitation for the period AD 1750 to 2005.


Do females differ from males? Dendrochronological study of Taxus baccata.

Anna Cedro¹, Grzegorz Iszkuło^2
1Climatology and Marine Meteorology Department, Szczecin University, Szczecin, Poland
²Insitute of Dendrology and Agricultural University, Faculty of Forestry, Poznań, Poland

    The research was carried out on five populations of common yew from western Poland; four protected in the reserves: „Cisy Rokickie im. Stanisława Króla”, „Cisy” and „Cisowa Góra” in the Kłodzko region, „Przełomy Książa pod Wałbrzychem”, as well as yew trees from the Arboretum in Kórnik. Altogether 196 samples were taken with Pressler increment borer from 98 female and 98 male trees. Based on measurements of annual growth rings, ten chronologies were produced (five for female specimens and five for male ones), which, in turn, were applied for dendrochronological and dendroclimatological analyses. Female specimens display lower convergence of individual dendrograms, more frequent reductions of annual increments, as well as generally lower values of their widths, comparing to the male specimens. Results of the signature year and the response function analyses are also pointing out different reactions to changing weather conditions at both the examined populations. Winter temperatures are the predominating factor affecting growth of the yew trees, female specimens, however, are also sensitive to the thermal conditions of the end of the previous vegetation season and June of the current season. Moreover, June and July rainfall seems to have higher impact on the cambium activity at the females, than at the male specimens. Different reactions growth-climate, depending on the sex of the yew trees, may present special influence on growth, development, as well as the extent of this tree species in the time of advancing climate changes.


Tree Ring and Climate Change Study in Nepal-A Case Study of Langtang National Park

Parveen Kumar Chhetri
Central Department of Environmental Science, Tribhuvan University, Katmandu, Nepal

    Analysis of available short term climatic data shows that climate is changing in Nepal including Langtang National Park of central Nepal. Long term climate trend is needed for proper understanding of climate change phenomenon and this can be achieved through dendrochronological study. Dendrochronology in Nepal is still in growing phase. Most significant studies have been carried out by Bhattacharyya et al., 1992, Cook et al., 2003 and Sano et al., 2005 with the other published and unpublished works. These studies show that Nepal has high potential of dendrochronological work which can be helpful in understanding past climatic variability and current climate change happening.  For present study a total of 120 tree cores from 60 trees of Abies spectablies (D.Don) Spach from two different sites of Langtang National Park have been collected. Local people perceptions toward climate change were also collected by key informants interview and interactions with elderly people. A 300 year long chronology was developed and response analysis of tree-ring parameter with available climate records show that the ring width was negatively correlated with May minimum monthly temperature and positively correlates with March and June total monthly precipitation. This result indicate that ring width is primarily controlled by the pre monsoon temperature and precipitation. On the basis of this result past climate was reconstructed which indicated recent global warming. Local people also felt abnormality in climate pattern which they believe to be the cause of law agriculture productivity and law productivity of grazing lands. They noticed changed in their surrounding in the form of less snowfall, intensive rainfall, frequent landslides, early blossoming of rhododendron species, low grass productivity in rangelands etc.


Climat, Gallic War and dendrochronology of oak (Quercus) in the first Century B.C.

Sébastien Durost¹ , Benoît Rossignol² , Georges Lambert³, Vincent Bernard^4
1Centre Européen d’Archéométrie, Université de Liège, B – Liège.
²Université Paris I Panthéon-Sorbonne, F – Paris.
³Laboratoire de Chrono-Écologie, UMR 6565 CNRS, Université de Franche-Comté, F – Besançon.
⁴Civilisations Atlantiques et Archéosciences, UMR 6566 CNRS, Université de Rennes 1, F – Rennes.
sebastien.durost@ulg.ac.be, benelsa@wanadoo.fr, joellamb@club-internet.fr, vincent.bernard@univ-rennes1.fr

    A comparison between dendrochronological and historical data requires a preparation that leads to several models. Dendrochronology produces three chronological models , a first one, a model of high frequency continuous and annual, a second one, which is smoothed (middle frenquency), and a third model, which is discontinuous and selects special years (event years). Although deduced ones from others, these models offer several points of vue on the environment and climate significance of the dendrochronological signal. Information from these three models are combined to build a spatial annual model. This model, for the first Century before Christ, in Northern France, shows particular situations for fifty two years. These situations were classified into ten classes. Classe C2 caracterizes a strong summer drought. It marked the year 54 before Christ, which precedes raising troubles in Gaul. The detailed analysis of the written historical information reinforce the hypothesis of the drought of 54 B.C. More, using arguments of type “delayed effects”, proposals are put forward events and troubles that happend in the years 53 and 52 B.C.


Comparison of radial growth response to precipitation and temperatures between dry and wet Scots pine (Pinus sylvestris L.) sites in Eastern Latvia

Didzis Elfert, Iluta Luce, Zane Strike, Guntis Brumelis
University of Latvia, Faculty of Biology, Riga, Latvia, LV-1586, didzis.elferts@lu.lv

    Previous studies in Kemeri bog (Latvia) have shown that there are differences in response to the climatic factor and ground-water level changes between dry and wet Scots pine sites – in wet sites growth is more controlled by the water-level but in dry sites more by temperatures and precipitation. To make general conclusions about the differences in response in dry and wet sites, it is necessary to extend studies to other sites, particularly where there has been no drainage conducted. For this purpose Gulbju bog was chosen. Gulbju bog is situated Eastern Latvia within the Gulbju and Platpirovas bog nature reserve. Trees in the dry soil site and bog site were sampled by coring (two cores per tree) in the year 2006. Tree ring widths were measured using measuring table or Lignovision, measurement quality was checked with COFECHA or TSAP and chronologies established using ARSTAN. Correlation analysis was performed to determine the relationship between climatic factors (mean monthly, autumn, winter, spring, summer temperature and precipitation sum) and chronologies. Regression analysis was conducted to determine the proportion of tree-ring width variation explained by the climatic factors. For regression analysis predictors were chosen using response function analysis using the program DendroClim 2002. Initial results show that at the wet site mean tree age is 100 years (minimal 69, maximal 158 years), at the dry site mean tree age is 136 years (minimal 92, maximal 188 years). At the wet site there were problems with cross-dating of tree-ring series because Scots pines growing on peat-lands tend to have compression wood.
Acknowledgment:
This study was partly supported by European Social Fund.


Lateglacial environmental changes as reflected in the Swiss pine chronology spanning 1606 years

Kaiser Klaus Felix^{1, 2}, Schaub Matthias^{1, 2}, Kromer Bernd³, Talamo Sahra3
¹Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
²Geographic Department, University of Zurich, CH-8057 Zurich, Switzerland
³Heidelberg Academy of Sciences, INF 229, 69120 Heidelberg, Germany

    During the last several years, significant progress has been made in the development of Lateglacial tree-ring chronologies in Switzerland with different sites on the northeastern Swiss Plateau near the cities of Winterthur and Zurich yielding multiple floating chronologies. Notably, work at new find sites (Gaenziloo and Landikon) has resulted in a new continuous pine chronology composed of 151 trees, spanning 1606 years between Bølling [BØ] (approx. 14,300 cal BP, 1950) and early Younger Dryas [YD] (approx. 12,750 cal BP). Additional radiocarbon dated floating chronologies and single trees appear to nearly bridge the ~200 year gap between the absolute chronology (12,593 cal BP). The filling of this gap will result in nearly a two millennia extension of the absolute chronology. Lateglacial pines usually grew under geomorphic stress and were gradually buried by loamy alluvia until the aggrading sediment killed the trees. Crossdating is complicated by both commonly observed growth disturbances during the first 100 years of a trees life and the poorer preservation of the outmost sapwood cells often characterized by warped tree-ring structures. Crossdating under normal conditions is based on an overlap of 50 up to 100 rings. Numerous decadal high precision 14C-age determinations assisted and verified the dendrochronological crossdating, although 14C plateaus and inversions between 12,700 and 12,300 cal BP complicated this procedure. Measurements of 140 decadal samples will provide a contribution to and extension of the 14C calibration curve. Initial results suggest a shift in the reservoir-correction offset of up to 250 years during the Allerød (AL). While fluctuations in the chronology are driven in part by local geomorphic activities, fluctuations may also coincide with short stadials and interruptions such as Older Dryas [OD], volcanic events (e.g., Laacher See eruption) and the Gerzensee deviation. Splitting the spline-detrended dataset into subgroups demonstrates the potential for detecting common environmental signals. Variations in age-related trends indicate changes in environmental conditions over the 2500 years spanning the AL, YD and Preboreal. Comparisons of tree growth and life span of trees between AL and YD suggest the YD to be rather a period of reduced winter temperatures than of low temperatures during the growing season. The dendroclimatic-style analyses presented herein are the first to be perfomed on Lateglacial tree-ring chronologies. Future efforts should focus on robustly preserving lower-frequency environmental variations and comparisons with other high resolution archives to quantify and calendrically date the main climatic fluctuations during the Lateglacial and early Holocene.


Effects of various site ecological features on radial growth pattern in North Rhine-Westphalia (W-Germany)

S. Fischer, B. Neuwirth, J. Löffler & M. Winiger
Institute of Geography, University of Bonn, Bonn, Germanye-mail: fischer@giub.uni-bonn.de

    Tree ring analyses are often focused on the investigation of climate/growth relations and their spatial variations. Many of them are based on dendrochronological networks which include more and more data from lowlands and low mountain regions. Nevertheless there is still a shortage of data from lower situated sites and in consequence a lack of knowledge about tree growth behaviour in these regions. For this study, which is located in North Rhine-Westphalia (West Germany), an already existent network with oaks will be completed with data from other tree species. 60 Tree-ring width chronologies for Fagus sylvatica, Quercus robur, Quercus petraea, Picea abies, Pinus sylvestris and Acer pseudoplatanus L. forms the multi species data set. The sampling sites are situated in lowlands as well as in low mountain regions with elevations ranging from 100 to 750 m a. s. l. They show varied expositions and inclinations and represent a great diversity of site ecological attributes. Detailed site information like soil of vegetation type is collected for forest ecological test areas in line with the Biomonitoring of the LANUV (former LÖBF). In this study the effects of various site ecological features on radial tree growth will be analysed. This investigation is based on an analysis of the radial growth pattern in North Rhine-Westphalia, applying single year analyses (according to Cropper) and interseries correlations.The talk presents the detected growth behaviour in a species specific and in a site ecological context.


Dendroecology of Quercus ilex in the Iberian Peninsula

G.; Gea-Izquierdo, D.; Martín-Benito, I., Cañellas
Departamento Sistemas y Recursos Forestales, CIFOR-INIA, Madrid, Spain, guigeiz@inia.es

    Dendrochronological studies from low elevations in the Western Mediterranean are scarce. Most dendrochronological studies in this region have used long-lived conifers from high elevations, being very scarce studies from broadleaf species. We present the first chronology (144 years) of Quercus ilex L., from a mesomediterranean site, and compare with other 42 Iberian chronologies. The most influential climatic variables upon Q. ilex growth were early summer precipitation which enhanced growth; and high temperatures in the previous August and current July which reduced growth. Very similar summer responses have been observed in other Mediterranean species such as Quercus suber L. Crossdating among chronologies was more related to a combination of orientation and altitude than to species. The Q. ilex chronology crossdated with many conifer chronologies from mid-high elevations, but were responding to a different climatic signal than Pinus pinea L. chronologies from low elevations. Termophyllous chronologies of this species from low elevations followed a distinct pattern in the PCA ordination, whereas the rest of the chronologies (mostly conifers from mid-high elevations) associated regionally. Iberian southern most chronologies from Andalusia were classified closest to P. pinea chronologies from lower elevations south of the Central Range. The Q. ilex chronology was clustered together with chronologies from the west Central Range and west-Southern locations of the Iberian range. These clusters were probably reflecting a common response to local precipitation.


Dendroclimatological aspects and wood formation dynamics of sessile oak in 2007

Jozica Gricar, Tom Levanič
Slovenian Forestry Institute, Department of Yield and Silviculture, Ljubljana, Slovenia, jozica.gricar@gozdis.si

    We investigated long-term variation in xylem ring widths, also in relation to climate, and seasonal dynamics of wood formation in 2007 of sessile oak (Quercus sessiliflora Salisb.) in Ljubljana, Slovenia (46°03’N, 14°28’E, 323 m a.s.l.). Local chronology of the investigated sessile oak span over 160 years, i.e. period 1848-2007. The mean xylem growth ring width (TRW) was 1.74 mm, the mean earlywood (EW) width 0.67 mm and the mean latewood width (LW) 1.03 mm. Raw data chronologies of the TRW, EW and LW demonstrated that the pattern of the variability in the TRW and LW coincides, whereas EW chronology was less variable and differed from the others. Pearson’s correlation coefficients calculated between residual xylem ring chronology of sessile oaks and climatic parameters showed that TRW was negatively affected by temperatures in June and positively by precipitation in March and June. Moreover, TRW proved to be negatively correlated also with the temperatures in July of the previous year and EW negatively with the precipitation in October of the previous year. Observation of cross-sections under light microscope revealed that cell division in the cambium started in all investigated trees before bud-break; i.e. at the end of March, when number of cambial cells increased. First xylem cells in stage of post-cambial growth were observed at the beginning of April, when superficially expanding vessels were distinctly noticeable. Secondary cell wall deposition and lignification initiated in the cell corners and middle lamella of vessels and neighbouring fibres in mid-April. The delay in wall thickening and lignification of the remaining tissue was very distinctive during the entire vegetation period. In the second half of April, second ring of earlywood vessels started to form. Seasonal dynamics of wood formation in all investigated groups of sessile oaks was described using Gompertz function. We detected first latewood tracheids in post-cambial growth at the end of May. Transition from early to latewood was identified by the decreasing diameter of the vessels, which were no longer arranged in characteristic rings. Rate of radial growth in this period slowed down. Latewood vessels with small diameters had smaller impact to the final TRW. By the end of August/ beginning of September, cambial activity ceased and the number of cells diminished. Xylem cells below the cambium were in the final stages of maturation at that time, and after one month the xylem growth ring of 2007 was fully developed. Although the test oaks were of comparable characteristics, we found differences in radial growth patterns among trees. Combination of inter- and intra-annual analysis of oak wood features revealed supplemental knowledge about radial growth of sessile oak at the selected location.


Carbon and oxygen stable isotope signals in Juniperus excelsa from Anatolia, Turkey – preliminary results

Ingo Heinrich¹, Ramzi Touchan², Kathrin Weidner¹,Gerhard Helle^1
1Research Centre Jülich, Jülich, Germany
²Laboratory of Tree-Ring Research, The University of Arizona, Tucson, USA

    The climate of the eastern Mediterranean is characterised by extremes of heat, highly variable precipitation, and limited water resources.  These features are of great significance to the growing human populations and can play a role in the dynamics of regional demographic, socio-cultural, economic, and environmental changes of the area. Therefore, understanding natural climate variability is of great importance as it will help to better predict its future variability, thus helping the societies affected to better adapt to the effects of climate change. Developing this understanding is difficult from the relatively short instrumental record available for the eastern Mediterranean region. Natural archives such as tree rings and other proxy records can be used to capture information about climate variability on longer time scales. Dendroclimatology has only recently been applied systematically in the eastern Mediterranean region but studies of carbon and oxygen stable isotopes in tree rings have not been conducted yet. We present carbon and oxygen stable isotopes series derived from tree rings of eight Juniperus excelsa trees from a site in Anatolia, Turkey. This site is part of a network of proxy data within the EU project MILLENNIUM assessing the climate variability over the last 1000 years throughout Europe. While measurements of carbon stable isotopes are still being conducted, first results for oxygen stable isotopes indicate significant correlation with precipitation. The dendroclimatological significance of both carbon and oxygen stable isotopes will be presented at the TRACE 2008 meeting.


Physiological processes of carbon isotope signal transfer from leaves to tree rings

Akira Kagawa
Wood Anatomy and Quality Laboratory, Forestry and Forest Products Research Institute, Tsukuba, Japan. (Current affiliation, Forschungszentrum Jülich GmbH ICG-V Jülich Germany)

    Stable carbon isotope ratio of leaf photosynthate reflects environmental conditions at the time of carbon fixation, and the fractionation process at the leaf level is explained rather successfully by conventional models. However, we still do not have a reliable model to explain how the carbon isotope signal at the leaf level is then transferred to tree rings. Understanding these key processes is indispensable for improving the quality of climate reconstruction. The first topic in this chapter is these signal transfer processes. 13CO2 pulse-labeling used in combination with high-resolution analysis of tree-ring isotopes is an effective tool to elucidate the processes of signal transfer. By pulse-labeling trees and analyzing the resulting distribution of the 13C label in the tree rings, we can visualize the deposition pattern of photosynthetic isotope signal to tree rings. In our studies on Larix gmelinii from Siberia, we have found that a significant portion of summer and autumn photosynthate is stored and used for earlywood formation in the following year. Based on the results from recent pulse-labeling experiments, we have developed a preliminary model that takes storage processes into consideration to explain the isotope signal transfer processes. The second topic is the time resolution of tree-ring isotope analysis when used as an environmental archive. Our key question is, “Do tree rings contain intra-annual information down to seasonal, monthly, weekly or even daily resolution?” From the widths of 13C peaks observed in tree rings of pulse-labeled trees, we have estimated the time resolution of tree-ring carbon isotope ratios and found it to range widely from weekly to yearly levels according to species and climatic regions. Finally, optimal microtome sectioning methods for tree ring samples will be also discussed to enable extraction of intra-annual information from tree rings at the finest resolution possible.
References:
Kagawa A. et al. (2006) 13CO2 pulse-labelling of photoassimilates reveals carbon allocation within and between tree rings. Plant, Cell & Environment 29, 1571-1584.
Kagawa A. (2008) Physiological processes of carbon isotope signal transfer from leaves to tree rings. Stable Isotope Dendroclimatology - Physiology, Systematics, Chronologies & Instrumentation. Eds. G.D.Schleser, G. Helle, S.W.Leavitt et al. Springer (in review).


Natural dynamics in dense, uniform subalpine forests

Frank Krumm¹, Momchil Panayotov¹, Peter Bebi¹, Heinrich Spiecker^2
1Swiss Federal Institute for Snow and Avalanche Research, Davos Switzerland
²Insitute for Forest Growth, University of Freiburg, Germany

    Large areas of subalpine forests in the Alps fulfil important protection functions against avalanches and other natural hazards. Dense c. 80-120 year old spruce dominated forests in the self-thinning phase are potentially critical concerning their sustainable protection functions.  While forest maintenance has generally aimed towards avoiding such dense and uniform stand structures, decreased funding for maintaining protection forests may cause an increase of such stands in remote areas of the Alps. However, but little is known about their natural dynamics without management. We investigate such unmanaged, dense forest structures (self-thinning stages) in the subalpine zone of the Alps in order to find out how long self-thinning processes last, and on which spatial scales disturbances occur. We also aim to gain knowledge about the possible differences in the protection function against natural hazards of managed versus unmanaged forests. A comparison with similar sites in the Bulgarian mountains will provide us information of untreated forests. We are using data from three Swiss forest inventories (LFI), 1985-1987, 1995-1997 and 2004-2007. With multivariate statistical methods we study the changes and the development in the study areas particularly concerning their protection functions. Furthermore we examine some plots with dendrochronological methods. This will provide us detailed information about stand history and tree age, and allow us to make conclusions concerning their dynamics. Preliminary results suggest that there are no considerable differences between managed and unmanaged forests concerning their protection functions in subalpine forests. Mainly small-scale disturbances occur in such dense subalpine forests.


Towards a 14000 Year Oak Chronology: Methods, Progress, and Challenges

Erin R. McMurry, Michael C. Stambaugh, Richard P. Guyette
Missouri Tree-Ring Laboratory, School of Natural Resources, University of Missouri-Columbia, Columbia, USA, ermfcd@mizzou.edu

    The value of millennial-length annual resolution tree-ring chronologies has increased exponentially as global climate change has moved to the forefront of many research interests.  While many such chronologies have been constructed, our research indicates that it may be possible to construct a Holocene-length chronology in the United States using subfossil oak buried in streams. Since 1999, we have collected over 500 subfossil oak (Quercus macrocarpa, Q. bicolor) cross-sections from glacial till streams and sediments in Missouri and Iowa (40°22' N, 93°18' W).  The alluvial streams flow through agricultural and forested lands and are low in gradient (~ 0.4 m/km). Stream channels meander in broad floodplains (0.5 to 3 km in width), are composed of sediments with low resistance to hydrologic erosion (glacial tills, silts, sands, and clays), and are generally unconstrained by bedrock.  Sub-fossil oak in these streams and sediments is relatively abundant (about 10 logs per km of stream reach) and well preserved.  Because of the high frequency of flooding disturbance, new oak wood is buried and uncovered with each flooding event. We use three methods for dating subfossil oak samples: a low-resolution density-based method, radiocarbon dating, and dendrochronological cross-dating. To date, over 370 pieces have been radiocarbon dated, with pieces dating from modern (<100 yrs) in age to over 14k yrs BP. An absolutely dated chronology has been constructed extending from AD 912 to 2004.  Several “floating” chronologies have also been developed: a 134-yr chronology at about AD 700; a 407-yr chronology at about AD 300; a 183-yr chronology at about 250 BC; a 273-yr chronology at about 500 BC; a 312-yr chronology at about 1800 BC; and, a 302-yr chronology at about 10000 BC. At present, we are working to connect these floating chronologies and extend the absolute dated chronology as far as possible. There are several challenging aspects to this endeavor, including: tree-ring segment length and temporal gaps in chronology, loss of wood cellular structure, storage and preservation of wood, abundance of wood available for sampling, and the length of time required for a project of this scope. Further collection of samples, more radiocarbon dates, and continued cross-dating work are planned as we work towards a long oak tree-ring chronology for the mid-continent region of the United States.


Climatic controls on intra-annual growth variations in larch and spruce along an altitudinal gradient in the Lötschental, Switzerland

L. Moser¹, P. Fonti², D. Frank², U. Büntgen², Julia Franzen², J. Esper^2
1Institute of Geography, University of Bern, Bern, Switzerland, moser@giub.unibe.ch
²Swiss Federal Research Institute WSL, Birmensdorf, Switzerland

    Forests, covering about 30% of all land area are among the most productive ecosystems and thus describe an important biosphere component with high cultural and commercial importance. Moreover, trees are one of the best sources on past climate variability, with long climate reconstructions strongly relying on their ability to contain a defined climatic signal. Knowing the sensitivity of tree growth to particular climate parameters is of great importance, especially when comparing the recent warming trend to past and future variations. Therefore, long-term understanding of intra-annual growth responses to climate variability and change describes one of the key questions in tree-ring research. Detailed knowledge on the precise timing and the amount of growth rates during the vegetation period and related biomass productivity needs to be assessed, and subsequently implemented in both modelling studies and improved climatic reconstructions. Here we assessed the influence of a warming climate on tree-growth. To reach this objective, we have selected a study location (Lötschental Valley in the Central Swiss Alps) that offers a 1000 meter elevational gradient within a confined geographical region. The Lötschental offers both north and south facing slopes that are forested from the valley bottom (~1300 m asl) to treeline (~2300 m asl) with inter-mixed evergreen spruce (Picea abies) and deciduous larch (Larix decidua) trees. The temperature change along this transect (~ 4°C) roughly corresponds with that projected for the year 2100. As effects from warming may involve non-linear and subtle shifts in growing season length and cellular activity, we placed particular emphasis on temporally highly-resolved (intra-seasonal) field measurements including: the weekly collection of microcore samples, hourly dendrometer measurements, weekly phenological observations, and in-situ meteorological measurements. Thousand micro-core samples were prepared as micro-sections and the number of cells in the different stages of development counted. Preliminary results show an air temperature change along the Lötschental-transect of about 4°C but only little difference due to exposure. Soil temperature decreases with altitudinal distance while exposure effects are more evident. The analysis of the phenological data reveals a clear delay of bud burst of larch and spruce with increasing altitude whereas the bud burst of Larch is about 30 days earlier. Compared to larch the bud burst of spruce shows hardly any exposure effects. Xylem formation data of 24 larches and 10 spruces indicate a similar trend as detected in the phenological data, above all the onset of enlargement and of cell wall thickening are delayed with increasing elevation. The ending of these stages of development does not reveal such a trend. Future research strategies along the Lötschental-transect will provide details on the timing and duration of tracheid growth for different growing seasons (2007-2010) and as a function of elevation, will allow determination of climatic influences upon growing season length and growth rates. These high-resolution data will be extended over the past couple hundred years by increment cores to retrospectively assess radial growth, density, and wood anatomical characteristics. As relative growth influences may change over time (e.g., as a function of mean temperature) and are additionally inter-correlated, a cambial growth model will be applied as an objective framework for investigating climatic forcing. In a two-way process, this model will be parameterized/verified by the intra-seasonal measurements, and will then be used to hindcast growth variations over the past 100+ years. Regionally available long instrumental temperature, precipitation, and radiation series should be employed for both empirical and modelling assessments. Expected results will, for the first time, integrate intra-annual observations, long-term measurements, and modeling runs of tree growth along an elevational transect, thereby providing new data and insights of species specific responses to temperature change.


Impact of climatic variation on growth and wood density of young poplar

Jorge Olivar
University of Freiburg, Germany

    Short-rotation forestry is regarded as a silvicultural practice employing high-density plantations of fast-growing tree species on fertile land with a short rotation period. Poplar species are often selected for these plantations since they produce large quantities of biomass in short periods of time. In the present study, samples from two poplar clones in two different sites were selected to evaluate their variation on growth and wood density concerning impact of climate. Ring features as the annual growth ring width and the dielectric constant of the wood were tested as potential short-term indicators of climate effects on tree growth and impacts on biomass production. High-frequency densitometry, as the method adopted in this research project, proved to be successful in permitting the non-destructive assessment of climate variation impacts on growth and wood density of young poplar. The approach used in this study of examining short-term climate responses of young poplar species on contrasting sites, clones and years would appear to be an important first step in understanding and anticipating responses to future climate change. The annual growth ring width correlated with the annual rainfall better than with the mean annual temperature in the study sample while the dielectric constant of the wood did not seem to correlate neither with the annual rainfall nor with the mean annual temperature on the selected young poplars. It showed a general slightly decreasing inter-annual pattern that could be interpreted as a decreasing density of the wood from pith to bark, with no clear impacts from the summer drought on 2003. There was a considerable decrease in above ground biomass production in 2003 as compared to the mean annual increment pattern of the period of time between 2001 and 2004. The annual biomass production was, apparently, more affected by the changes of the annual growth ring width than by the changes in the wood density, as it was considered to have rather constant values along the 4 years of the study. Therefore, the decrease in biomass production in the year 2003 might be interpreted as a consequence of the decrease of the ring width, more strongly influenced by the attenuation of precipitation than by temperature.


Pinus peuce and Pinus heldreichii tree rings as a key to past mountain climate in Southeastern Europe

Momchil Panayotov^1,2, Peter Bebi², Steffan Yurukov¹, Frank Krumm^2
1University of Forestry, Sofia, Bulgaria
²Swiss Federal Institute for Snow and Avalanche Research, Davos, Switzerland

    We present two tree-ring chronologies from subalpine forests in Pirin Mountains, Southwestern Bulgaria. The first chronology is from Macedonian pine (Pinus peuce Griseb.), an endemic species located in several regions on the Balkan Peninsula and listed in the IUCN Red List of Threatened Species. The second one is from Bosnian pine (Pinus heldreichii Christ), which is also a rare species found mostly on the Balkans and in isolated stands in Southern Italy. Some of the best-preserved forests from these species are located on steep slopes near the treeline in Pirin National park. Pinus peuce trees grow on North and West exposures mostly on soils above granite rocks, while Pinus heldreichii forests can be found on South and East exposures on soils above marble rocks. Since these species grow at close distance to each other, but on slopes with different ecological conditions, it is interesting to compare their relationship with the most varying climate elements - temperature and precipitation. We have collected cores from breast height with increment borer. After measuring the tree ring widths, the obtained numerical series were cross-dated with the use of visual clues and the computer program COFECHA. Master-chronologies construction was performed with ARSTAN software using modified exponential and liner functions for standardization. At the present moment the Pinus peuce chronology is 300 years long, while the Pinus heldreichii one is 700 years long. Climate-growth relationship analysis was performed with DENDROCLIM2002 software using average monthly temperatures and precipitation sums for months from June of the year prior to growth to September of the present year. The chronologies have significant correlation with each other. While most of the years with lowest and highest indices are the same, there are certain years, in which they deviate. This demonstrates that although tree-ring growth is responding in similar way to the common for the two species hydrothermal regime, additional factors, which are site-dependent and differ for the two species, also have importance in certain years. Climate-growth relationship analysis shows that while Pinus peuce is mostly dependent on temperatures in the growth season of the previous and the present year and responds positively to high temperatures, Pinus heldreichii cambial activity is limited by low summer precipitation. This provides the opportunity to obtain information both for temperature and precipitation variation in the mountain by studying the chronologies simultaneously. This is of increasing importance in the context of growing need of knowledge about the past and present climate variation in different parts of the world and the fact that proxy climate data is almost missing for the region.


Carbon, oxygen and hydrogen isotopes in tree rings - a climate and anthropogenic impact study

Slawomira Pawelczyk¹, Anna Pazdur¹, Malgorzata Szczepanek¹, Tatjana Boettger², Marika Haupt², Marek Krapiec³, Elzbieta Krapiec-Szychowska^3
1Department of Radioisotopes, Institute of Physics, Silesian University of Technology, Gliwice, Poland,  Slawomira.Pawelczyk@polsl.pl
²UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Sektion Hydrogeologie, AG Paläoklimatologie; Halle/Saale, Germany
³Dendrochronological Laboratory, AGH University of Science and Technology, Cracow , Poland

    Tree rings preserve climatic and environmental data and therefore tree rings widths, maximum late wood density and other parameters such as stable isotopic composition can be used for reconstructing of past climatic and environmental changes. Investigations of stable isotopic C, H, and O composition in alpha-cellulose extracted from tree rings of pines (Pinus sylvestris L.) and oaks (Quercus Robur L.) growing in the Suwalki region (North Eastern Poland) and Niepolomice Forest (Southern Poland) were undertaken. Presented isotope records cover the period of 1600-2003. Those measurements constituted a part of more complex investigations of stable isotopic composition in tree rings for last 400 years in the frame of European project ISONET. Values of δ13C, δ18O and δ2H measured in the tree ring a-cellulose are compared to meteorological data (temperature, precipitation, sunshine). On the basis of those investigations δ13C, δ18O, δ2H can be regarded as indicators of summer climate change. Relations between isotopic and meteorological data (temperature and precipitation) demonstrate that precipitation influences the stable isotopic carbon, oxygen and hydrogen ratios to a lower extend than temperature. Carbon isotopes are widely used as indicators in the study of atmospheric CO2 variability in space and time. After removing individual components of δ13C originating from climatic factors (temperature and precipitation) greenhouse CO2 emission for Polish region was estimated.


Hydraulic architecture of Avicennia marina (FORSSK.) VIERH. along an ecological gradient in Gazi Bay, Kenya

Elisabeth M. R. Robert^1,2, Nele Schmitz^1,2, James G. Kairo³, Hans Beeckman², Nico Koedam^1
1Vrije Universiteit Brussel (VUB), Laboratory for Plant Biology and Nature Management (APNA), Brussels, Belgium
²Royal Museum for Central Africa (RMCA), Laboratory of Wood Biology and Wood collection, Tervuren, Belgium
³Kenya Marine and Fisheries Research Institute (KMFRI), P.O. Box81651, Mombasa, Kenya

    Although mangroves have been extensively studied, little is known about their functional wood anatomy so far. The aim of this study is to measure and to make an ecological interpretation of different wood characteristics (vessel density, vessel grouping and vessel diameters) of Avicennia marina (FORSSK.) VIERH. (Avicenniaceae), a species with a broad local distribution and a representative of the genus with the largest latitudinal range. Relationship between these wood characteristics, measured in 35 trees from seven different sites in Gazi Bay on the east coast of Kenya, and two environmental factors (salinity and inundation frequency) as well as different tree characteristics (Leaf Area Index, tree height and tree diameter) were investigated. A comparison with Rhizophora mucronata LAMK. (Rhizophoraceae), another mangrove species with a different ecology and habit but also growing in Gazi Bay, was made. Results have shown different ways in which the hydraulic system of A. marina seems to be adapted to local environmental conditions. Higher vessel density and higher vessel grouping was observed with higher soil water salinity. More stressful environmental conditions were related to smaller radial vessel diameters and smaller vessel area. Mean vessel density and vessel grouping was higher in A. marina compared to R. mucronata. Furthermore A. marina had smaller vessel diameters and vessels of mainly horizontally elliptic, almost round shape. We can conclude that the plasticity in vessel characteristics of A. marina towards environmental factors at least contributes to the capacity of A. marina to grow in sites with of diverse environmental conditions. It seems that this species is better adapted than other mangrove species to a large range of stressful environmental conditions by a safe hydraulic system (high mean vessel density, high vessel grouping and small, almost round vessels). This is a possible explanation of the ecologically broad local distribution and the wide latitudinal range of the species.


Dendroecological studies on Bosnian Pine (Pirin Mountains, Bulgaria)

Jörg Scheithauer¹, Karsten Grunewald¹, Gerd Helle², Jürgen König³, Björn Günther^3
1Landscape Research Centre Dresden, Germany
²Research Centre Jülich, Institute of Chemistry and Dynamics of the Geosphere (ICG), Germany
³University of Technologies Dresden, Institute of Forest Utilization and Forest Technology, Germany

    Coniferous trees at the subalpine forest- and timberline are excellent archives for climate proxies. The lack of knowledge in the fields of modern climate development in southeast Europe and high level ecology of the peripheral mediterranean regions shall be closed by physio-geographical analyses of extreme stands in the northern Pirin Mountains conbined with dendroecological analyses on Bosnian pines. In this talk parameters of site and growth are utillized to characterise the timberline ecotone. Particular relief and soil characteristics are tightly related to tree physiology and tree-ring width. In the vicinity of the forestline Bosnian pines on slightly evolved rendzinas with an average tree-ring width of 1.0mm are predominant, whereas timberstands are dominated by narrow annual rings and regosols resp. skeleton soils. The chronologies created for three test areas with different site parameters evince similar curve shapes. Umpteen global events are saved in the series of annual rings which partly reach back more than 700 years for example the Maunder-Minimum of sunspot activity 1672-1704 and the eruption of Katmai in 1912. Further this talk gives a prospectus on the Bosnian pine´s potential as a climate archive. In particular the average temperatures in spring and the annual amount of snowfall days correlate significantly with tree-ring width.


Circulation patterns as origin of negative pointer years from Central European tree-rings

J. Schultz, B. Neuwirth, J. Löffler, M. Winiger
University of Bonn, Department of Geography, Bonn, Germany, schultz@giub.uni-bonn.de

    Tree growth is influenced by many ecological factors. Especially the climate conditions are essential for tree-ring growth. The predominant factor for the climate conditions in Central Europe is the large-scale circulation which can be described by a classification with 29 weather regime types, the so called Großwetterlagen (GWL). All 29 GWLs are associated with different air masses. These air masses have got their own specific combination of properties in terms of temperature, moisture etc. Furthermore the weather conditions during one GWL are not homogeneous because each GWL has got its own distinctive pattern regarding the weather conditions. This pattern is modified by the topography and the changing tracks of the anticyclones and cyclones. The aim of the study is to find out the impact of the circulation pattern, derived from the GWL record, on the spatial pattern of negative pointer years (calculated with Cropper) in Central Europe for the period from 1900 to 1976. The first step is to explain the spatial pattern of the Central European negative pointer years with a specific combination or persistence of the various GWLs. The next step is to establish a linear relationship between the detected GWL constellations and the tree-ring width chronologies. For this study 300 dendrochronological sites with all important Central European forest-tree species are used (Abies alba, Fagus sylvatica, Larix decidua, Pinus cembra, Pinus uncinata, Picea abies, Quercus petrea, Quercus robur). The sites represent a varying ecological spectrum regarding altitude, inclination, exposition and forest community. All chronologies cover  the period from 1894 to 1982 and consist of about 12 dominant trees. The talk presents the impact of the GWL on the spatial pattern of negative pointer years in Central Europe. It shows that persistence and appearances of specific GWL constellations are responsible for the spatial pattern of the negative pointer years in Central Europe.


A flood ring of Celtis sinensis found in the following year of the 1896 autumn extreme flood of Lake Biwa, Japan

Kenjiro Sho¹, Miklós Kázmér^2
1Department of Civil Engineering and Systems Management, Nagoya Institute of Technology, Nagoya, Japan,
²Department of Palaentology, Eötvös University, Budapest, Hungary

    300-year chronologies of peak water level and rainfall in floods have been reconstructed using historical documentary records for Lake Biwa, central Japan. In this study we analyzed the signature of an extreme flood in autumn of 1896 on tree rings aiming at developing an estimation method of flood water level from tree-ring records to supplement the documentary records. The sample tree of this study is an enoki hackberry (Celtis sinensis Pers.) with 70 cm DBH and 117 rings that used to grow in the yard of Izu Shrine located at the west shore of Lake Biwa. This tree was felled during 28-31th July in 2002, and the cut-down trunk is still in place. We took four disks from the stump and the trunk at the positions corresponding to 1, 2, 3, and 4.5 m height above the ground. The elevation of soil surface at the position of the sample tree was surveyed as BSL (Biwa Standerd Level; 84.37 m a.s.l.) +2.63 m. Comparing to the daily observation record of lake level, the base of this tree should have been inundated for 24 days from 9th September to 2nd October in the 1896 flood. As a result of observation under stereomicroscope, a flood ring with abnormally thin alignment of earlywood vessels of relatively small diameter in the pore zone was found in the 1897 ring on each disk. This feature is the most significant at the 1 m height and less obvious at higher positions. The measured ring-width series indicated the abrupt drop in growth in 1897 and the suppressed growth persisting for several years thereafter. It looked the recovery of growth is comparatively faster at lower positions. Some ring-porous species are known to form a flood ring with the features described above in the case where the tree is inundated for weeks in the season when the earlywood vessels are formed in the corresponding year. Therefore, such signature of inundation has been applied only to reconstruction of past snowmelt floods in spring. The result of this study implies the possibility that severe damage on trees by prolonged inundation in autumn can cause the formation of flood ring in the following year of the event.</