V. Balodis

Valdis Balodis, Didzis Tjarve and Andris Kalnins

Department of Botany and Ecology, University of Latvia, Kronvalda blvd. 4,

LV 1842 Riga, Latva

Abstract.

Changes in environmental quality were investigated using annnal tree ring width time series for the previous 42 years. Tree core samples at 1.3 m height were collected from 20 and more trees in each of 76 plots, in similar dominant Scotch pine forests (Norway spruce understorey) throughout Latvia. Cored trees were aged 70 - 100 years. For each plot the mean relative additional annual increment values, and the cumulative relative additional annual increment values for the retrospective periods 1971 to 1980 and 1981 to 1990, were determined in relation to the control period 1959 to 1969. In almost all cases, significant decreases in expected growth were observed in areas with known anthropogenic sources of stress. Negative additional increment values occurred near the Mazeikai Oil Refinery (began operation in 1990), the Skrunda Radio Location Station (began operation in 1971), around urban areas (Riga, Olaine etc.) and close to previous Soviet military bases.In a few areas signifcant decrease in growth cannot presently be explained and further work is required in those areas to determine possible sources (drainage, pests etc.).

In general the tree increment time series have adequately reflected changes in environ-mental quality in Latvia. The major benef~t of dendroindicative assessment is that retrospective comparison can be achieved.

Abstract:

The ongoing development of tourism in the Alps is about to increase the potential of damage by natural hazards. Particularly hazardous are mud and debris flows. On the occasion of the 1989 event we started to investigate the debris fan of Multetta, Val Mustair, neor Tschierv (Switzerland), dating debris flows and trying to ascertain their frequencies. The loose tree stand covering the fan allows age determinations by dendrochronological methods, focussing on abropt changes in growth, scars, and the formation of aUventitious roots, which can all be dated on the grounds of tree rings. Since the end of the 1 5th century six aggradations heve thus been differentiated by analysing adventitious roots and two more have been determined through interpreting scars.

Silvio Borella

ABSTRACT

Theoretical models and measurements of precipitation waters show that measurements of D ¹⁸O and D ¹³C of cellulose of tree rings is a potential means to reconstruct D ¹⁸O of precipitation water and climate. Its well known that D ¹⁸O of precipitation depends among other parameters on the condensation temperature, and theoretical considerations show that evapotranspiration produces an enrichment of the leaf-water in the heavy isotopes, which depends on the relative humidity of the surrounding atmosphere. On the other hand a fractionation model of carbon assimilation shows that less opened stomata leads to a lower fractionation during assimilation, hence to higher D ¹³C values.

We measured these two parameters from several locations on the Swiss Plateau for the last 50 years and compared them with precipitation water and meteorological parameters. Spring temperature is the main influence of the long-term variations (> 10 years) of the oxygen isotope content, whereas the relative humidity causes short term variations (year to year). The carbon isotope content is mainly influenced by the summer precipitation amount. Our experiments confirm theoretical expectations.

Besides these tree ring measurements, we tested the influence of the cellulose extrac-tion on isotope values. These tests showed that an incomplete extraction (due for example to too coarsely milled wood) can lower the D ¹³C value of up to 0.15, and increase the standard deviation of the overall method to more than 0.1 which is 5 times more than the reproducibility reached with very fine milled standard cellulose.

Dieter Eckstein, Dirk Dujesiefken, Hamburg

Abstract

Increment boring means wounding the tree and causes discoloration with subsequent colonization by fungi. There are considerable differences between tree species as re-gards the efficacy of a tree to compartmentalize a wound. The treatment of boreholes using special chemical substances is of only minor influence. However, the season of sampling plays an important role, at least with broadleaved trees. Each increment bor~ng should only be done after having considered the pros and cons.

The Yenisey River Driftwood in Siberia - a dendrochronological study

Abstract for Eurodendro97

Dr. Olafur Eggertsson

Department of Quaternary Geology

Lund University

Tornavagen 13

223 63 Lund

Sweden

Driftwood occurs on most beaches in the Arctic and on nearby islands that are influenced by arctic water, e.g. on the shores of islands in the North Atlantic Ocean, the Bering Sea and Baffin Bay. The amount of driftwood varies greatly, from scattered logs to beaches completely covered with wood.

The driftwood presently resting on the arctic coasts originates in the circumpolar boreal forest regions. Rivers draining these regions to the north carry the wood into the Arctic Ocean. The occurrence of the wood is due to two different processes; 1 ) trees wither began drifting because of natural processes, or 2) because of human activity. The first group includes trees with their root system preserved when they were washed ashore on an arctic beach, meaning that they were eroded from a river bank. The second group includes trees that have obviously been cut with a saw before they began drifting, indicating that they came loose during timber rafting.

During the summer of 1995, samples were collected from driftwood for dendro-chronological studies from the banks of the Yenisey River in Siberia between the villages Jenissejsk in the south and Komsa in the north. A total of 500 samples were collected.

The aim of this fieldwork was to get a representative collection of driftwood that is currently transported by the Yenisey River to the Arctic Ocean and to prove a earlier stated hypothesis that a large amount of driftwood presently resting on the shores of Iceland and Svalbard originates from the Yenisey River drainage. The driftwood samples were analyzed dendrochronologically and compared with earlier constructed driftwood chronologies from Iceland and Svalbard. The stated hypothesis could be proven to be right showing a high synchronisation between the Yenisey River driftwood and the wood resting on the Atlantic Islands.

Devon is the third largest county in England and is also one of the wealthiest counties in terms of its historic standing buildings. Yet the available chronology coverage is remarkably poor. The chronologies available for the period AD1000 to the present day are dominated by timbers from buildings and archaeological sites in Exeter, which is the major town/city in Devon. The rest of the county is represented by only two replicated chronologies. A number of other buildings have been analysed but the dendrochronological success rate has been very low. As a consequence it was decided to set up a research project in the county with the following aims:

1. To extend the network of reLerence chronologies in a currently underrepresented problem area.

2. To enhance the understanding of the development of buiding techniques and timber technology by providing precise dating evidence.

3. To provide evidence concerning the historic landscape and man's interaction with woodlands of the past.

4. To obtain information concerning the effects of the varied geography of the county on tree growth.

5. To assist assessment of the importance of protection of buildings and thier future management.

Cathy Groves

Dendrochronology Laboratory

Archaeology Research School

Dept of Archaeology & Prehistory

Sheffield University

West Court

2 Mappin Street

Sheffield S 1 4DT

UK

Sheila Hicks¹ Olavi Heikkinen² and Mervi Tuovinen²

1Department of Geosciences, University of Oulu, FlN-90570 Oulu, Finland

2Department of Geography, University of Oulu, FlN-90570 Oulu, Finland

FOREST (Forest Response to Environmental Stress at Timberlines: Sensitivity of Northern, Alpine and Mediterranean forest limits to climate) was accepted as a project within the Environment and Climate section of the European Union IVth Framework programme. Work started in February 1996 and the project will run initially for 3 years. Thirteen Universities or Research Institutes are involved from 9 different European countries (Finland, Norway, UK, Germany, France, Switzerland, Austria, Portugal and Greece). The co-ordinator is Docent Sheila Hicks while the other members of the Oulu group are Olavi Heikkinen, Mervi Tuovinen, Jyrki Autio and Petri Pellikka.

The objectives of the project are to determine the effects of environmental stress on European timberline forests, and then to predict the effect of the anticipated global warming on the timberline. This involves: 1) The production of a calibration data-set of climate/environment factors and tree growth responses over the last 100 years along transects across the timberline in Northern Fennoscandia and on the Alpine and Mediterranean mountains, 2) The use of this data-set to model the effects of climate on timberline forests, 3) Testing of the model on past situations of timberline and climate different from today, and 4) The building of a model to predict the responses of timberline forests to future changes in climate.

The Oulu group is focusing on three aspects. Firstly monitoring modern pollen deposition and establishing its relationship to both the surrounding vegetation and annual variations in climate. Secondly the detailed monitoring of meteorological factors across the altitudinal timberline and thirdly the dendroecological analyses (tree-ring width and density) of timberline pines. Finnish material is also the basis for other analyses including needle density and needle retention (Rovaniemi Forest Research Institute), the density of stomata on needles (Bergen University), the stable carbon isotope content of the late pine wood (Swansea University), the cell structure and seasonal growth of pine (Hamburg University) and comparative fossil pollen material (Helsinki University).

B. Kupper, A. Giesemann, H.-J. Weigel, S. Klas, I. Wohler, S. Augustin, G. Buttner,

M. Duve

. Keywords: Forest Decay, S02 - Air Pollution, Industrial Emission Source, Specific Impact, Integrated Monitoring, S02 - Distribution Model, Deposition - Model, Structured Sampling, Chemical Fingerprinting, Passive Monitor Bark, CIR-Analysis, Visible Injury, Lichens, Ecological Variation, Soil Analysis, Critical Levels & Loads, Dendroanalysis, Tree Ring Width, S, d34S, K, Ca, P, Mg, Na, Mn, Ba, B, Sr, Cu, Zn, Ti, Rb, Pb, Ce, Co, La K, Ca, Al, Fe, Si, CalAl, Mn/Ba, Ratio Specific Impact Source / Background Pollution, pH Soil, N-Impact Agriculture, ICP-MS, MS, RMA (EDAX), Pollution Chronology

Abstract:

The task was to identify the specific air pollution impact of an S02 - emission source in respect to manifested forest decay in the area. For this purpose we started an Integrated Monitoring Model in 1993 and finished it in 1996. It consisted of four main compartments:

1. Distribution of air pollution and ecological effects. This included the analysis of the emissions, the estimation of the S02- immission by a Gaussian Distribution Model, measurements of air pollution depositions with bark as passive monitor and ecological effects at more than 150 sites (CIR, terrestrial investigations of wood damages, lichens as indicators for S02- impact, tree ring width reductions, soil analysis, needle analysis).

2. Chemical Fingerprinting to distinguish between the specific impact of the emission source on one side and the impact of the background pollution and other sources on the other side: S, stable isotopic ratio of sulphur d34S, and 54 elements.

3. Characterising the ecological variation in respect to forest types, exposition and soils in the area at 27 sites.

4. Chronology of pollution history and ecological effects (records of emissions from begin of operation since 1971 to 1994, Gaussian distribution model in 3-year-periods, Dendroanalysis (tree ring width and chemical fingerprints) from 1955 until 1994, partially back until 1850.

Levanic, T., Cufar, K., Hudolin, Zupancic, M., EURODENDRO '97, Savonlinna, Finland,

28.5-1 .6.1997

Tom LEVANIC*, Katarina CUFAR*, Jernej HUDOLIN**, Martin ZUPANCIC*

*Biotechnical Faculty, Department of Wood Science and Technology,

Vecna pot 2, pp 95, Sl-1001 Ljubljana, Slovenia,

**Slovenian Restoration Centre, Plecuikov trg 2, Sl-1000 Ljubljana, Slovenia

Introduction. Piran is located at the Adriatic coast of Slovenia, approx. 100 km Southeast of Venice. Archaeological investigations have shown that the territory was more or less continuously populated since the prehistoric time. The history of the town was strongly influenced by the Republic of Venice to which it belonged from 1283 to 1797. The medieval centre of the town, where there are nineteen churches and other sights, is well preserved. The church of St. George dominates on the hill and is the biggest church in the town. The excavations and the archived documents indicate that the present church was built by reconstruction of the former romanic, gothic, and baroque ones.

The objective of the study was to conduct a dendrochronological investigation of the roof construction to:

• complete the existing information on the age and past reconstruction of the roof,

• determine the proportion of the elements belonging to different constructional phases,

• get information on possible re-using of the wood.

Results and discussion. The wood identification has shown that the main construction is made of larch (Larix decidua Mill.) and the supporting elements of silver fir (Abies alba Mill.). 88, i.e. 90%, of the investigated cores replicated floating chronologies, two larch and one silver fir, were constructed. Most samples (74%) were included in this chronologies. The dating was possible using the larch chronology from the Italian Eastern Alps

results of the dating are presented in the following table:

As main results we could clearly identify and distinguish the specific S - impact of the air pollution source in space and time.

University of Ljubljana, Biotechnical Faculty, department of Wood Science & Technology, pp 95, Sl-1001 Ljubljana, Slovenia 1

The part of Dendroanalysis was to check the chronology of the pollution and to date some ecological effects. Emissions from the factory were recorded since begin of operation in 1971 until 1994, the additional S02 - immissions at the site could be calculated by the Gaussian distribution model over the time. In combination with the chemical fingerprints, especially the d34S - ratios in the tree rings, it was possible to distinguish the specific S - impact of the source from other S-impacts in the area and the background pollution. The influence of another major S - source since the fifties could be identified. The specific S - impact of the factory appeared in the tree rings after begin of operation in 1971 and it could be followed up until now. Reductions in tree ring growth occurred since the fifties. They increased stepwise after begin of operation and the system collapsed in the eighties, when reductions became as heavy as 50% and more. The Ca/A1- ratio in the tree rings dropped in the fifties, indicating that important changes in soil - pH and the collapse of the exchange buffer system occurred already in this time. The Mn/Ba - ratio turns over 1 after the fifties increasing with time. The Mn/Ba identifies as major influence for the acidification the S02 - pollution. P and Mg increased in the eighties, coinciding with the last collapse of the system: They show up the N - impact of high industrialised agriculture, which was implemented in the area during that time (large pig and poultry stockings). NH4 increases the S-deposition and the acidification of the soil.

The correctness of the dating was additionally confirmed by analysis of signature years and visual comparison of the curves.

Due to the slightly degraded and brittle outer sapwood it was nearly impossible to measure all rings immediately below the "Waldkante" or the bark, which indicates that an important reconstruction of the roof took place after 1262, 1594 and 1878. Individual rafters were built during smaller reparations of the roof. 26% of the samples could not be dated.

It was observed that most rafters were re-used. It is assumed that the former churches at the same location were approximately of the same size as the present church.

By analysing all samples, two continuous larch chronologies spanning the periods 888-1262 and 1399-1807 were built, but its replication is low in some periods. Therefore it is not possible to discuss the probability of 1-2 missing rings in the master chronology of Bebber around 1400, as mentioned by Friedrich, Spurk and Nicolussi (personal communication).

We assume that the wood originates from the NE Italian Alps. Tree ring analyses of larch trees from Slovenia are planned to obtain additional information to discuss the provenience of the wood.

The work was funded by the Slovenian Ministry of Science and Technology and by the Slovenian Restoration Centre.

Literature: Bebber, A. E.,1990. Una cronologla del larice (Larix decidua Mill.) delle Alpi orientale italiane. Dendrochronologia, 8, s.119-140. Levanic, T.,1996. Dendrochronological and dendroecological study of dominant and co-dominant silver firs (Abies alba Mill.) in Dinaric phytogeographic region. Dissertation thesis, Ljubljana, University of Ljubljana, Biotechnical Faculty, Dept. for Wood Science and

Technology,165 s.

University of Ljubljana, Biotechnical Faculty, department of Wood Science &

Technology, pp 95,

Sl-1001 Ljubljana, Slovenia

Institute of botany and ecology, Tartu University

Estonia has long been a blank patch in a dendrochronological map of Europe. At present, tree-ring research is carried through by the author at Tartu University.

In 1994, following advises of Prof. D. Eckstein, I initiated a dendrochronological research project of dating rooLs of country churches in Estonia. The project found no fonding by Estonian Science Foundation. It did not fit either under botany or under history. There was no such a discipline as dendrochronology in their list of sciences. In spite of that I consulted with art historians and started sampling with a borer in Estonian country churches. Kind help by Institute for Wood Biology of University of Hamburg, where I was invited to elaborate the tree-ring samples, provided to carry through the research.

Meanwhile, Estonian Maritime Museum has tried to date ship wrecks by tree-rings.

For today, 31 historical buildings, mainly churches, were sampled by A. Laanelaid. Twenty object chronologies of them were dated, initially by using a Gotland pine chronology and other reference chronologies at the Institute for Wood Biology of University of Hamburg. Several Estonian object chronologies cross-dated between themselves. The building timber in Estonia consisted nearly exclusively of pine and spruce. Among 502 cores there were 279 cores (56%) of pine (Pinus sylvestris L.) and 223 cores (44%) of spruce (Picea abies Karst.). Some constructions were built of both pine and spruce. Other constructions were made of only pine or only spruce timber. Oak (Quercus robur L.), although growing naturally in this area, is a rare exclusion in buildings. There were a few oak beams found in excavations at the ancient fortification hill in Tartu. The horizontal beam of triumph arc of St. John's church of Tartu was made of oak.

The twenty dated chronologies fell into 17to 19 centuries (mostly 18 century). North War in the beginning of 18 century was destructive for many bnildings in Estonia: very seldom older wood can be found. Separate chronologies were built up for pine and spruce. In churches I took samples from their roof constructions. Thus their dates refer to renewal of the roofs, not to the original building of the church itself Dating of Uppsala House in Tartu is made jointly with Dr. J. Merilainen and Dr. O. Eggertsson. Most of the chronologies were dated by the help of Prof. D. Eckstein. The undated chronologies wait for new local reference chronologies. It seems that pine chronologies are better datable than spruce chronologies. In 1997 the project will continue with sampling in a number of country churches in Estonia.

MATERIAL AND AIMS

An old disc of Scots pine was found in the barn close to the Forest Research Station in Pu~kaharju. The disc was observed there already in 1972. Where did it come from and when?

The comparison of the disc with a number of regional chronologies of Finland proved the best fit with the pine chronology of eastern Lapland.

CONCLUSION

The pine disc came to Punkaharju from eastern Lapland aÎter the summer of 1963 (the last tree-ring), likely in the car of some forestry employee working or visiting at Punkaharju.

Later the disc was divided into two parts. One part preserved in the floor of Lusto.

Jouko Merilainen, Esko Jarvelainen and Markus Lindholm

University of Joensuu

Saima Centre for Environmental Sciences

Linnankatu 11

FIN-57130 SAVONLINNA

telephone +358-15-5759 861 Telefax +358-15-5759 852

Email jouko.merilainen@joensuu.fi

esko.jarvelainen@joensuu.fi

markus.lindholm@joensuu.fi

Esko Jarvelainen', Markus Lindholm² and Jouko Merilainen³

A master tree - ring chronology of Scots pine has been built for eastern Finland. The research area covers a region surrounding the central parts of the Lake Saimaa basin, between 29° - 30° E and 61 ° - 62° N. Currently our chronology starts in the year 974 A.D.

Altogether 250 living trees were sampled in ten areas. Ring - width was measured to the nearest 0.01 mm. The resulting measurement series were standardized. Ring - width series from different subareas correlated highly with each other and thus enabled the construction of ten areal chronologies. Also the areal chronologies synchronized well with each other producing a regional chronology.

In order to extend the chronology temporally, samples were taken from wooden structures of numerous historical buildings in the town of Savonlinna and nearby villages. In addition, sample were taken from logs found at the bottom of three small lake. The dead trees were measured and standardized by the same way as the living trees. Currently over 300 dead trees are succesfully ross - dated and combined with the master chronology. The regional chronology has already been used for dating purposes, e.g. the wooden structures of medieval castle, the Olavinlinna. In addition, the chronology will be used for dendroclimatological purposes, viz. comparison of growth responses between northern and southern boreal zones

71,2 and 3

University of Joensuu

Saima Centre for Environmental Sciences

Linnankatu 11

FIN- 57130 SAVONLINNA

telephone +358-15-5759 861 Telefax +358-15-5759 852

Email jouko.merilainen@joensuu.fi

Esko.esko.jarvelainen@joensuu.fi

markus.lindholm@joensuu.fi

Paola NOLA

Dipartimento di Ecologia del Territorio - Università degli Studi di Pavia, Italy

Climbing ivy (Hedera helix L.) is usually considered a competitive species for the "host" tree and it is regarded as a growth inhibitor. Therefore, in most cases climbing ivy was cut or removed from productive forests.

Recently some authors have reviewed the ecological role of ivy addressing the question whether it is really a competitive or a cooperative species. This dendroecological study is an attempt to find some answers to the question.

Within a beech stand in the "Foresta Umbra" (Gargano, Apulia) 54 cores were taken from 29 beeches and 16 cores from 8 beech-climbing ivy. Beech cores were measured and individual chronologies obtained for each tree. Growth releases from suppressions were detected in order to date disturbance in the beech stand. Ivy cores were used to date the establishment of each climbing ivy. Then the average growth of host-trees was calculated for different periods, before and after the establishment of climbing ivy, whose effects on beech growth were then assessed.

All the host trees seem to benefit of the presence of climbing ivy, as indicated by a general growth increment.

This result is discussed taking into account stand disturbance history and the role of climbing ivy within the forest ecosystem.

Possibilities to improve expressed enviroomental signal (EPS) derived from tree ring chronology was studied on 19 trees sampled from a permanent Scots pine (Pinus sylvestris L.) thinning experiment in southern Finland. Trees of varying relative size from thinned and untinned plots, as well as radii in different compass directions and different positions at the stem were compared.

EPS values incressed with increasing number of chronologies sampled. The effect of incressing tree number was more pronounced compared to increasing number of radii per tree. EPS increased also when the social status of a tree improved but no clear differences between unthinned and thinned trees were found. Further, no clear trend existed between different heights at the stem. Highest EPS values were found in directions of west, southwest, and south; accordingly, the lowest value was at the north side of the bole followed by sides to northeast and east.

It was concluded that some reduction of noise present in tree ring chronologies may be achieved by paying more attention to sample selection within and between stems. Especially, sunny side of the bole as well as dominant trees shouid be preferred. However, the most important factor in noise reduction is adequate replication.

1)Finnish Forest Research Institute, P.O Box 18, 01301 Vantaa, Finland

2)University of Helsinki, Department of Forest Ecology, c/o Saima Centre for Environmental Sciences, Linnankatu 11, 57130 Savonlinna, Finland

Anna-Liisa Pirhonen ¹ and Markus Lindholm ²

' University of Helsinki, Department of Geology, P O. Box 11, 00014 University of Helsinki, Finland University of Joensuu, Saima Centre forEnvironmental Sciences, Linnankatu 11, 57130 Savonlinna, Finland

The research area of this work is located about 60 kilometers north of the actual forest limit, at Kevo of the Utsjoki region in Finland, 69°45'21" N and 27°00'45"E (Figure 1). In this region the growing season is short. Although temperatures are generally low, there is enough light for growth, since the sun shines almost continnously day and night throughout the growing season. However, below zero temperatures at nights disturb growth frequently.

The warmest month of the year is July (12,1°) and the coldest is January (-15,3°) The Arctic Ocean has strong influence on local weather. During winter for example the temperature may change very rapidly from -30° to above zero degrees. There exists also sharp climate differences between locations in the mountains and in the valleys.

43 trees were sampled from two areas located on glasifluvial terraces in a river valley, about 90 - 1 10 meters above the sea level. The soils of these dry fields are very acid podsols and easily permeable to water, as is characteristic of northern forest stands. The sampled trees were relatively young, 45 - 110 years old. Samples were taken from three directions according to the point of the compass using an increment borer. Ring-widths were measured to the nearest 0.01 mm. All the measurement series were cross-dated, standardized and developed into site chronologies (Figure 2). Negative exponentials and alternatively regression lines were applied in modelling the growth trends to be removed.

In calibration, the traditional response function analysis was used to study the growth responses of pines to climatic factors. 24 climate variables, including mean monthly temperatures and total precipitations, were used to predict radial growth. In order to handle the effects of typically strong autocorrelation, three prior growth variables were used in response functions together with the climate variables.

Unexpectedly, the response function analyses revealed that the mean monthly temperature in August is the most important climatic factor affecting the growth of these pines (Figure 3). The amount of precipitation during June proved to be an almost equally good predictor. The results are in contrast with the well known fact that mid-summer temperatures determine the radial growth of pines in the forest-limit region. However, the work described here was done beyond the actual timberline, in a region where the Arctic Ocean has strong influence on climate. In addition, it has to be borne in mind that the trees studied here were relatively young. It is reasonable to expect different age groups of trees to have different responses.

O.M. Raspopov, O.I. Shumilov, E.A. Kasatkina (SPbF IZMIRAN,

P.O. Box 188, St.-Petersburg, 191023, Russia

E-mail: oleg@omr.izmi.ras.spb.ru)

N.V. Lovelius (Botanic Institute of RAS, St.-Petersburg, 197022, Russia)

Tree-ring data collected close to forest timber-line give important information on climatic variation in the Past. However under processing of the data one should be certain that the trce used had not had technological influence which during few years increased greatly on environment at northern regions. This influence on environment is especialy pronounced at Kola peninsula where the nickel plants, many open mines and other industrial objects are located. As a result of our investigations we revealed those regions of Kola peninsula where the influence on nickel plants on the forest was most pronounced and those areas where the technological influence was practicaly absent. The last ones as it was obtained were located along Tuloma river. Using tree-ring data taken in the region it was obtained that climatic variation on the Past demonstrated cyclic character. The frequencies got correspond to main ones of the solar activity and as well to the frequencies which are combinatory frequencies from main solar activity ones. The last fact demostrates that solar variability action on Earth environment has non-linear character.

Giorgio Strumia, Michael Grabuer and Rupert Wimmer

Wood Biology and Tree Ring Research Group

Universitat für Bodenkultur Wien A-1180 Vienna

First results of a dendroclimatological investigation conducted mainly in the Wiener Becken, south of Vienna (Lower Austria) with Black pine (Pinus nigra ssp. austriaca) are presented.

This species grows mostly on poor and soils with low water storage capacity. The climate is dry and warm during the growing season with annual precipitation down to 500 mm which let us hypothesise that precipitation is the limiting growth factor of black pine.

Over 200 trees were sampled at 20 different sites covering an area of about 50 km (north-south) by 20 km (east-west). Cores were measured using the LINTAB+ device to the nearest 0.01 mm. We have measured total ring widths as well as the widths of earlywood and latewood. Data management and cross-dating were done by mainly using TSAP+ software with visual checking and final quality control using COFECHA. Special care was taken with frequently encountered intraannual density variation.

The black pine sites proofed to be highly sensitive (up to 0.40) with signal to noise ratios up to 16.5. Mean interval trend, which is the percentage of samples with a upward or downward trend, was calculated with the aim to evaluate the pointer years in each site. A table with the years which present a negative or positive trend in more than 75% of the samples was produced. The table shows pointer years that appear in at least 75% of the sites for the last 200 years:

Negative pointer years

1832, 1857, 1865, 1901, 1907, 1915, 1917, 1956, 1959, 1965, 1968, 1976

Positive pointer years

1871, 1876, 1878, 1897, 1902, 1916, 1936, 1945, 1972, 1989, 1994

To find the limiting climatic factors for the tree growth we did also a preliminary response function analysis using the PRECON program. Three sites were selected and the raw data were standardised using ARSTAN. With climatic data (Hohe Warte / Vienna) representative for the region we found that precipitation of May, June and

July is the most limiting factor for the annual growth of the trees. Separate use of earlywood and latewood widths revealed even a more significant relationship with monthly precipitation. In summary, Black pine has proofed to be very useffil for the reconstruction of summer rainfall in the pannonic region. Further analysis should make this possible for the last 500 years.

References:

CHRISTENSEN, K.I. (1987): Taxonomic revision ofthe Pinus mugo complex and

P.x rhaetica (P. mugo x sylvestris) (Pinaceae). Nord. J. Bot. 7 (4): 383-408, Copen

hagen.

SCHMID, JENNIFER; BOGENRIEDER, A. und SCHWEINGRUBER, F. H., 1995:

Verjtingung und Wachstum von Moorkietern (Pinus rotundata Link) und Fichien

(Picea abies AL.A H. Karsten) in Mooren des sadostlichell Schwarzwaldes (Suid

deutschland).

Mitt. Eidgenoss. Forsch.anst. Wald Schnee Landsch. 70, 2: 175-223.

Jennifer Schmidl, Arno Bogenriederl and Fritz H. Schweingruber2 1 Institute for Biology II - Geobotanik, University of Freiburg, Schanzlestr. 1, 79104 Freiburg, Germany 2Swiss Federal Institute for Forest, Snow and Landscape Research, 8903 Birmensdorf, Switzerland

In the Black Forest, a mountain range in the South of Germany, the edges of raised bogs are mainly settled by Pinus rotundata Link, the bog pine. The bog pine belongs to the mountain pine group, the Pinus mugo Turra complex. A detailed taxonomic revision ofthis species complex is given by CHRISTENSEN (1987).

Pinus rotundata grows only in rather poor habitats such as very wet open bog sites and drier wooded bog sites. The ecological balance of most of the bogs in the Black Forest is disturbed by different activities of man like draining, peat cutting, lumbering or

using this habitat for waste disposal.

Thus, as you can observe, the vegetation of many raised bogs is changing. This has an impact on many populations of bog pine. To preserve this species, it is necessary to

study the ecological factors which influence its regeneration.

Studies of germination, establishrnent and growth of young trees in a raised bog show that "light" is an important factor for the regeneration of Pinus rotundata (SCHMID et al. 1995). Light increases the germination rate of bog pine seeds. Furthermore, in undisturbed bogs the conditions on open sites are more favourable for the establishment of young bog pine seedlings than the conditions on wooded sites. More than 40 % of marked seedlings survived the first two years on open bog sites. However, on

wooded, shady bog sites the seedlings have little chance to survive. Spruce also germinates on undisturbed bogs, but the seedlings are not able to establish themselves.

They die atter a few months.

Matters are quite different on drained peat bogs. Here you can observe the successful establishment of spruce. Furthermore they grow much faster than bog pines. On such sites the vegetation is undergoing a change. The bog pine has to compete with the invading spruce. In the long term the bog pine will disappear on such sites because it

cannot regenerate in the shade of spruce.

Studies of the wood anatomy of young trees growing on bogs show how extreme the conditions for tree growth on a bog are. Young trees generate a lot of reaction wood. Out of 100 investigated cross sections, 96 samples showed reaction wood. The fonnation of reaction wood is probably caused by the pressure of wet and heavy snow at the end of almost every winter.