TRACE Tree Rings Archaeology Climatology Ecology

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Roots - the hidden key players in estimating the potential of Swiss forests to act as carbon sinks. H. Gärtner & O.U. Bräker Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland; e-mail: gaertner@wsl.ch Introduction The role of root systems in the CO 2 budget of forests is still largely unknown. One of the reasons is doubtlessly the extraordinary effort involved in gathering information about the size and spread of a complete root system of a tree. In recent years, multifaceted modeling approaches have been developed based on existing data to assess the root spread of different tree species (Adiku et al. 1996; Brown et al. 1997; Lynch 1997). More recently, models have been developed to estimate root biomass (Cairns et al. 1997; Laclau 2002; Vogt et al. 1998). The results are ambiguous: they show widely differing percentages of calculated root biomass vs. above-ground biomass. These differences also apply to existing conversion factors that include root biomass into the computation of total biomass. Possible reasons for these differences are the difficult accessibility of the roots and, more importantly, the varying environmental factors affecting root growth. According to Schmid- Haas & Bachofen (1991), who investigated root systems of uprooted Norway spruce saplings, the radii of these roots depend basically on: (i) (ii) (iii) <strong>Tree</strong> size (positive correlation to breast-height diameter) Soil type (negative correlation to soil porosity) Stand density (negative correlation to stand density) According to this investigation, the variability of the size of root systems (of for example Norway spruce) is very high. However, it should be noted that this investigation did not take into account the coarse roots which remained in the soil. Furthermore, the pH-value of the soil influences the longitudinal growth of roots. The root growth of Pinus pinaster showed a reduced longitudinal growth at a pH-value of 3.5 (higher values at pH 6.5), whereas biomass values according to an increased secondary growth are high (Arduini et al. 1996). The ROOKEY-project (Roots – the hidden key players) at the Swiss Federal Research Institute WSL aims to analyze root systems of wind-thrown European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) saplings, to enable the computation of sitedependant correlations between above-ground and below-ground biomass. There are two main questions to be answered in this project: (i) which role do roots play related to above ground biomass; (ii) is the presently increased growth of trees based on a shift in the relation between above-ground and below-ground biomass? This report concentrates on the role of roots related to above ground biomass. 13
Material and methods In the first phase of the project, existing data (root-ball dimensions) of 128 European beech and 129 Norway spruce saplings thrown by the “Lothar” storm-event in the winter of 1999 were analyzed. Next, correlations were calculated between the different root-ball parameters (radius, diameter, depth) and the respective breast-height diameter (dbh) of the stem. In order to enable accurate calculations, all above ground parameters of the trees (height of stem and crown, dbh, age and growth rates) were taken into account. The disadvantage of this approach is that root-ball data represent the volume of the whole root ball, instead of the volume of the real root system (figure 1). Consequently, the soil has to be removed to analyze the real biomass of the root system. For this reason, the root system of a 120 year old Norway spruce, also thrown in 1999, was exposed to get an impression of the real amount of roots. Unfortunately, all fine roots were decayed and bigger parts of the coarse roots were rotten. The coarse roots could nevertheless be sampled for analysis of the relationship between longitudinal and radial growth of the vertical and horizontal roots. A) RbR R B) RbR RbR RbD Rbd W RbD W Rbd W W = Root collar;: RbR = Root-ball radius, RbD = root-ball diameter, Rbd = root-ball depth Figure 1: A) Measured root-ball data. Root distribution and biomass can only be estimated. B) Real biomass determination can only be done after the removal of the soil Additionally, the root systems of 15 naturally-grown European beech and 28 Norway spruce saplings (age: 5 – 10 years) were excavated, and their spread, volume and weight were measured. In August 2002, a thunderstorm threw a 150-year old European beech in the area of Zürich, Switzerland. The fracture points at the coarse roots around the root ball were rather small, so about 95% of the whole root system was covered in the root ball. The topicality of the event ensured the possibility to expose the coarse as well as the fine roots for biomass calculation. After exposing the whole root system it was cut off and transported in peaces to the lab. Further analyses were based on a 3D grid dividing it into sectors of 30cm (see figure 2 and 3). Currently, roots belonging to each sector are being cut out and their volume and weight are being measured. 14
Page 1 and 2: Forschungszentrum Jülich in der He
Page 3 and 4: Schriften des Forschungszentrums J
Page 5 and 6: Bibliographic information published
Page 8 and 9: CONTENTS SECTION 1 ECOLOGY A. Bräu
Page 10: T. Vernimmen and U. Sass-Klaassen:
Page 13 and 14: Tree-ring studies in the Dolpo-Hima
Page 15 and 16: Rara MLD (Abies) Rara RW (Abies) Ts
Page 17: Cook, E.R., Krusic, P.J. & P.D. Jon
Page 21 and 22: Correlations for all trees (no site
Page 23 and 24: Acknowledgements The authors wish t
Page 25 and 26: Results and interpretation Species
Page 27 and 28: Figure 3: Multitemporal maps of est
Page 30 and 31: SECTION 2 GEOMORPHOLOGY
Page 32 and 33: Zurich Geneva Study site Zermatt Fi
Page 34 and 35: lot of debris-flow events can be se
Page 36 and 37: Changes in growth rates and wood an
Page 38 and 39: Growth reductions and eccentricity
Page 40 and 41: 40% of all trees in the landslide a
Page 42 and 43: Figure 1: Location of study areas H
Page 44 and 45: Ai− rBi Eccentricity for year i i
Page 46 and 47: The event frequency per year for th
Page 48: Shroder, J.F. (1980): Dendrogeomorp
Page 51 and 52: Temporal and spatial variability of
Page 53 and 54: 120 100 80 (Dlink/Dmax)*100 60 Uppe
Page 55 and 56: Figure 6: Results of stepwise clust
Page 57 and 58: Figure 8: Forest types and forest d
Page 59 and 60: The first principal component of a
Page 61 and 62: Figure 2: Correlations of the 1 st
Page 63 and 64: NAO and Tree Rings - A dendroclimat
Page 65 and 66: 5°E 10°E 15°E 50°N 45°N Figure
Page 67 and 68: The smaller bars show the number of
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a b c d Significant correlating are
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Neuwirth, B., Esper, J., Schweingru
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Unterspreewald,Brandenburg,Germany
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Unterspreewald, Brandenburg, German
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Leuschner, H.H., Delorme A. & H.-C.
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Figure 1: Location of the monitorin
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Figure 3: Examples of the distribut
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On the potential of cedar forests i
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At every site, two cores per tree w
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Maximum replications are reached in
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Schweingruber, F.H., Eckstein, D.,
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developed that can be used to study
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4 3 2 1 0 -1 -2 normalized Schmidha
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This value is based on the fact tha
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Stokes, M.A. & T.L. Smiley (1968):
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The use of stable isotope dendrochr
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3.0 2.5 Z74 2.0 1.5 1.0 0.5 0.0 3.0
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Conclusions The combined stable car
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The climatic signal in oxygen isoto
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Results Figure 2 shows the raw ring
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Secondly, the records are short and
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Jouzel, J., Hoffmann, G., Koster, R
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Although the difference between min
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SECTION 5 PALAEO-ENVIRONMENTS
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Results and discussion Of 59 oaks a
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Acknowledgements This research was
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Great efforts on small woods Analys
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Some 250 of them - mainly beeches (
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References Billamboz ,A. (1990): Da
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coefficient can be expected from in
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country region covered by theCATRAS
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Figure 2: Map of the Netherlands an
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Jansma, E., Sass-Klaassen, U., de V
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The aim of the current study is to
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Figure 1: Map of archaeological sit
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0.8 correlation coefficient (r) 0.4
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Acknowledgements We would like to e
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Figure 2: 17th century forgery (Mus
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1400 1450 1500 1550 1600 1650 1700
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Table 2 - Average annual-growth ind
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Conclusion The data set we studied
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Figure 1: Collapsed foundation (Pho
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A list of the archaeological sites
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personal communication) believe tha
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Table 4: Success rates of the dendr
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wood with no strong common tree-rin
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Jansma, E. (1996): An 1100-Year Tre
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Malacochronology, the application o
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Fladen Grounds 100 m Norway 30 m UK
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higher with the chronology of growt
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0 140 200 growth index 120 100 80 6
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an underlying mechanism but demonst
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Witbaard, R., Jenness, M.I., Van de
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TRACE 2003 Utrecht (NL) 1 st -3 rd
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TRACE 2003 Utrecht (NL) 1 st -3 rd
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Schriften des Forschungszentrums J
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Forschungszentrum Jülich in der He
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