Showing papers by "Swiss Federal Institute for Forest, Snow and Landscape Research published in 2003"
TL;DR: An interpretation of anomalies found in the wood structure and, more generally, of cambial activity in such environments are presented and a classification of tree‐ring formation in mediterranean environments is proposed.
Abstract: We review the literature dealing with mediterranean climate, vegetation, phenology and ecophysiology relevant to the understanding of tree-ring formation in mediterranean regions. Tree rings have been used extensively in temperate regions to reconstruct responses of forests to past environmental changes. In mediterranean regions, studies of tree rings are scarce, despite their potential for understanding and predicting the effects of global change on important ecological processes such as desertification. In mediterranean regions, due to the great spatio-temporal variability of mediterranean environmental conditions, tree rings are sometimes not formed. Often, clear seasonality is lacking, and vegetation activity is not always associated with regular dormancy periods. We present examples of tree-ring morphology of five species (Arbutus unedo, Fraxinus ornus, Quercus cerris, Q. ilex, Q. pubescens) sampled in Tuscany, Italy, focusing on the difficulties we encountered during the dating. We present an interpretation of anomalies found in the wood structure and, more generally, of cambial activity in such environments. Furthermore, we propose a classification of tree-ring formation in mediterranean environments. Mediterranean tree rings can be dated and used for dendrochronological purposes, but great care should be taken in selecting sampling sites, species and sample trees.
394 citations
TL;DR: The authors developed a quantitative chironomid-July air temperature inference model based on surface sediments from 81 Swiss lakes and applied it to the Holocene subfossil chironmid record of Hinterburgsee, a small subalpine lake in the northern Swiss Alps.
Abstract: We developed a quantitative chironomid-July air temperature inference model based on surface sediments from 81 Swiss lakes and applied it to the Holocene subfossil chironomid record of Hinterburgsee, a small subalpine lake in the northern Swiss Alps (present-day mean July air temperature of 11.3°C). After smoothing to reduce the high between-sample variability of inferred temperatures, the reconstruction indicates July air temperatures of 10.4– 10.9°C at the end of the Younger Dryas, of 11.9–12.8°C during the early and mid-Holocene (11500–4000 cal. BP), and slightly lower temperatures of 11.5–12.0°C during the late Holocene (3500–1000 cal. BP). A warming trend inferred for the past millennium is most likely an artifact of human impact on Hinterburgsee's chironomid fauna, rather than a genuine temperature signal. The most prominent climatological events during the Holocene were two periods of lower temperatures at c. 10700–10500 cal. BP and 8200–7700 cal. BP and an abrupt shift to a cooler late-Holocene cl...
250 citations
TL;DR: In this article, the influence of climatic factor changes on tree-ring growth at high latitudes was investigated to investigate influence of seasonal growth and tree cell-wall thickness in larch trees at six sites near the northern timberline in Siberia.
Abstract: Wood material for at least 12 larch trees at six sites [Larix sibirica Ldb, Larix gmelinii (Rupr.) Rupr, Larix cajanderi Mayr] near the northern timberline in Siberia was analyzed to investigate influence of climatic factor changes on tree-ring growth at high latitudes. Tree-ring cell size, maximum latewood density and ring width measured by means of image analysis and X-ray radiodensitometry and calculated latewood cell-wall thickness were used. Correlation analysis of tree-ring structure parameter chronologies with temperatures averaged over periods of 5 days (pentad) shows that early summer temperature (mean for 5–6 pentads, depending on the region, starting from the middle of June) and date of snow melt are the most important factors that define seasonal growth and tree-ring structure. Analysis of instrumental climatic data indicates that a positive trend of early summer temperature was combined with winter precipitation (October–April) increase and this combination leads to later snow melt. Based of the results of tree-ring growth modelling, it was shown that later snow melt (hence, delayed initiation of cambial activity and, as a result, decrease of wood production) explains the changes in the relationship between tree ring width and summer temperature dynamics observed after the 1960s for a large area of the Siberian Subarctic. The understanding of the role of winter precipitation in controlling ring growth, through its effect on the timing of cambial activation, suggests the possibility of using ring structure parameters to create reconstructions of past winter precipitation variations.
227 citations
TL;DR: In this article, the authors used radiocarbon-dated sediments from four lakes in Switzerland to study palynologically the effects of climate change on harvest yields and found that harvest yields would have increased synchronously over wide areas of central and southern Europe during periods of warm and dry climate.
186 citations
TL;DR: In this article, the effects of increased N deposition on new and old pools of soil organic matter (SOM) were investigated, where spruce and beech growing on an acidic loam and a calcareous sand were exposed to increased N and elevated atmospheric CO 2.
Abstract: The aim of this study was to investigate the effects of increased N deposition on new and old pools of soil organic matter (SOM). We made use of a 4-yr experiment, where spruce and beech growing on an acidic loam and a calcareous sand were exposed to increased N deposition (7 vs. 70 kg N ha −1 yr −1 ) and to elevated atmospheric CO 2 . The added CO 2 was depleted in 13 C, which enabled us to distinguish between old and new C in SOM-pools fractionated into particle sizes. Elevated N deposition for 4 yr increased significantly the contents of total SOM in 0–10 cm depth of the acidic loam (+9%), but not in the calcareous sand. Down to 25 cm soil depth, C storage in the acidic loam was between 100 and 300 g C m −2 larger under high than under low N additions. However, this increase was small as compared with the SOM losses of 600–700 g C g C 0.25 m −1 m −2 from the calcareous sand resulting from the disturbance of soils during setting up of the experiment. The amounts of new, less than 4 yr old SOM in the sand fractions of both soils were greater under high N deposition, showing that C inputs from trees into soils increased. Root biomass in the acidic loam was larger under N additions (+25%). Contents of old, more than 4 yr old C in the clay and silt fractions of both soils were significantly greater under high than under low N deposition. Since clay- and silt-bound SOM consists of humified compounds, this indicates that N additions retarded mineralization of old and humified SOM. The retardation of C mineralization in the clay and silt fraction accounted for 60–80 g C m −2 4 yr −1 , which corresponds to about 40% of the old SOM mineralized in these fraction. As a consequence, preservation of old and humified SOM under elevated N deposition might be a process that could lead to an increased soil C storage in the long-term.
165 citations
TL;DR: In this paper, two different types of hydrological models, the physically based WaSiM-ETH model and the conceptual PREVAH model, were used to simulate runoff generation in the Rietholzbach and Dischmabach catchments.
Abstract: In mountainous catchments the quality of runoff modelling depends strongly on the assessment of the spatial differences in the generation of the various runoff components and of the flow paths as coupled with the amount and intensity of precipitation and/or the snow melting. These catchments are also suitable for the intercomparison of different kinds of hydrological models, particularly of different approaches for the simulation of runoff generation. Two differently structured catchment models were applied on the pre-alpine Rietholzbach research catchment (3.2 km 2 ) within the period 1981-98 and on the high-alpine Dischmabach catchment (43 km 2 ) within the period 1981-96 for the simulation of hydrological processes and of the runoff hydrographs. The models adopted are the more physically based WaSiM-ETH model, with grid-oriented computation of the water balance elements, and the rather conceptual PREVAH model, based on hydrological response units. The simulation results and the differences resulting from the application of the two models are discussed and compared with the observed catchment discharges, with measurements of evapotranspiration, soil moisture, outflow of a lysimeter, and of groundwater levels in three access tubes. The model intercomparison indicates that the two approaches for determining runoff generation with different degrees of complexity performed with similar statistical efficiency over a period longer than 15 years. The analysis of the simulated runoff components shows that the interflow is the main runoff component and that the portion of the runoff components depends strongly on the approach used. The snowmelt model component is of decisive importance in the snowmelt season and needs to take into account the role of air temperature and radiation for simulating runoff generation in a spatially distributed manner.
163 citations
TL;DR: In this paper, the authors investigated the mechanisms enabling plants to tolerate high concentrations of available Cu in their rhizosphere, and showed that the complexation of Cu2+ ions in the root apoplasm by phenolic compounds could alleviate Cu-mediated toxicity.
Abstract: The mechanisms enabling plants to tolerate high concentrations of available Cu in their rhizosphere are still poorly understood. To better understand the mechanisms involved, Lupinus albus L. (white lupin) was grown over 40 days in a hydroponic system compelling roots to develop under sterile conditions in the presence of a nutrient solution containing 0.5, 20 or 62 μM Cu. The following parameters were investigated in detail: low molecular weight phenols in nutrient solution (colorimetric assay), high molecular weight phenols in roots and in solution (HPLC-MS, HPLC-UV), pH, redox potential in solution (electrochemistry) and Cu distribution in the plant (AAS) as well as in apical root sections (EDX microanalysis). Finally, in vitro adsorption studies using voltammetry were conducted to evaluate the Cu adsorption behaviour of different phenolic compounds. When exposed to 62 μM Cu, biomass production of white lupin was strongly reduced. Plants grown in the presence of 20 μM Cu had a similar dry matter production compared to the control plants grown in a 0.5 μM Cu solution. However, an increased release of soluble and high molecular weight phenols into the solution was observed. The concentration of polyphenolic compounds in the roots (particularly isoflavonoids like genistein and genistein-(malonyl)-glucoside) was significantly higher for lupins grown in a 20 μM Cu solution compared to the control plants. As shown by an in vitro adsorption study, these phenolic compounds can bind Cu ions. In addition, plants exposed to 20 and 62 μM Cu cumulated high Cu amounts in root cell walls whereas only low amounts reached the symplasm. Therefore, it is proposed that the complexation of Cu2+ ions in the rhizosphere and in the roots apoplasm by phenolic compounds could alleviate Cu-mediated toxicity.
159 citations
TL;DR: In this article, the authors proposed a framework for a mathematical unification of geostatistics, mul- tivariate data analysis, and the analysis of variance that may enable ecologists from a broad range of fields to incorporate spatial effects into their research and to integrate analyses across different levels of biological organization.
Abstract: Spatial structure in plant communities occurs in the forms of (1) single- species aggregation and dispersion patterns, (2) distance-dependent interactions between species, and (3) the response to the spatial structure of environmental conditions. Different methods deal with these components of spatial variation: geostatistical analysis reveals autocorrelation in a spatial sample; the variance of species richness has been used as an indicator for interspecific interactions due to niche limitation; and ordination techniques describe multispecies responses to environmental factors. Based on the mathematical prop- erties of presence-absence data, it is shown how variogram modeling, the testing of in- terspecific associations, and multiscale ordination can be integrated using the same set of distance-dependent variance-covariance matrices (variogram matrix). The variogram matrix partitions the variance of community data into spatial components at the levels of the individual species, species composition, and species richness. It can be used to factor out the effects of single-species aggregation patterns, interspecific interactions, or environ- mental heterogeneity. The mathematical integration of traditionally unrelated methods in- creases the interpretability of variograms of plant communities, provides a spatial extension and an empirical null model for the variance test of species richness, and extends multiscale ordination to nonsystematic spatial samples. Beyond the individual applications, the var- iogram matrix provides a framework for a mathematical unification of geostatistics, mul- tivariate data analysis, and the analysis of variance that may enable ecologists from a broad range of fields to incorporate spatial effects into their research and to integrate analyses across different levels of biological organization.
125 citations
TL;DR: Application of the modified TTC assay to seedling roots stressed either by drying or by exposure to the toxic metals Cd or Al resulted in significant decreases in TF formation that were related to both the duration of stress and the concentrations of toxic substances, indicating that themodified TTC assay can be used to assess the physiological condition of roots.
Abstract: Reduction of triphenyltetrazolium chloride (TTC) by tissue to the red-colored insoluble triphenylformazan (TF) is directly linked to the activity of the mitochondrial respiratory chain Thus, only living tissues should reduce TTC to TF However, TF production can be detected when the TTC test is applied to control tissues boiled in water This artifact is mainly the result of the hot ethanol extraction step, which is used to disintegrate the cells and solubilize the TF We observed that cell wall materials such as cellulose and pectin interact with TTC at temperatures above 60 degrees C, reducing the TTC to TF By replacing the hot ethanol extraction step with an extraction procedure that involved grinding the boiled tissues and extracting the TF with ethanol at room temperature, the formation of TF was almost entirely eliminated Application of the modified TTC assay to fine roots of Norway spruce from forest topsoil indicated that the extent of TTC reduction was related to root morphological class as: white fine roots > brown fine roots > black fine roots > boiled fine roots, corresponding to formation of 108, 61, 02 and 01 mM TFg(-1)DW, respectively No significant differences in TTC reduction were recorded between fresh and frozen tissues (frozen in liquid N2) for any fine root class Application of the modified TTC assay to seedling roots stressed either by drying or by exposure to the toxic metals Cd or Al resulted in significant decreases in TF formation that were related to both the duration of stress and the concentrations of toxic substances, indicating that the modified TTC assay can be used to assess the physiological condition of roots
119 citations
TL;DR: In this article, the effect of a forest fire on the hydrogeological response of a given catchment was analyzed in terms of territorial safety in the Riale Buffaga watershed.
Abstract: The debris flow of 28 August 1997 which occurred in the Riale Buffaga, a torrent channel in the territory of the village of Ronco s./Ascona (Ticino, Switzerland), has been simulated with a good degree of reliability due to the existence of morphologic surveys of the torrent channel preceding the flood event and the presence of a rain gauge that registered the rainfall event at a resolution of 10 minutes. With these data it is possible to conduct a quantitative analysis of the effect of a forest fire on the hydrogeological response of a given catchment. In the case at hand, a 10-year rainfall event caused a 100- to 200-year flood event. This result clearly quantifies the possible consequences of a forest fire in terms of territorial safety. Copyright © 2003 John Wiley & Sons, Ltd.
97 citations
TL;DR: In this paper, the influence of different soil types on the net input of new C into soils under CO2 enrichment and the stability and fate of these new C inputs in soils was estimated.
Abstract: The aim of this study was to estimate (i) the influence of different soil types on the net input of new C into soils under CO2 enrichment and (ii) the stability and fate of these new C inputs in soils. We exposed young beech–spruce model ecosystems on an acidic loam and calcareous sand for 4 years to elevated CO2. The added CO2 was depleted in 13C, allowing to trace new C inputs in the plant–soil system. We measured CO2-derived new C in soil C pools fractionated into particle sizes and monitored respiration as well as leaching of this new C during incubation for 1 year. Soil type played a crucial role in the partitioning of C. The net input of new C into soils under elevated CO2 was about 75% greater in the acidic loam than in the calcareous sand, despite a 100% and a 45% greater above- and below-ground biomass on the calcareous sand. This was most likely caused by a higher turnover of C in the calcareous sand as indicated by 30% higher losses of new C from the calcareous sand than from the acidic loam during incubation. Therefore, soil properties determining stabilization of soil C were apparently more important for the accumulation of C in soils than tree productivity. Soil fractionation revealed that about 60% of the CO2-derived new soil C was incorporated into sand fractions. Low natural 13C abundance and wide C/N ratios show that sand fractions comprise little decomposed organic matter. Consistently, incubation indicated that new soil C was preferentially respired as CO2. During the first month, evolved CO2 consisted to 40–55% of new C, whereas the fraction of new C in bulk soil C was 15–23% only. Leaching of DOC accounted for 8–23% of the total losses of new soil C. The overall effects of CO2 enrichment on soil C were small in both soils, although tree growth increased significantly on the calcareous sand. Our results suggest that the potential of soils for C sequestration is limited, because only a small fraction of new C inputs into soils will become long-term soil C.
TL;DR: A highly significant correlation is found between the changes in the numbers of plant species and red deer, with species richness increasing with increasing deer density, and a sharp increase in species richness between 1917 and 1999.
TL;DR: In this article, an improved photographic method of analysing vertical vegetation structure was designed to study various spatial parameters, especially in pione er and grassland ecosystems, following standardised data sampling in the field based on digital photography.
TL;DR: It is suggested that the genetic variation among CHV-1 subtypes did not evolve in Europe and support the hypothesis of multiple introductions of CHv-1 into Europe.
TL;DR: In this article, the authors used Canonical Correspondence Analysis (CCA) as a prediction tool and image segmentation as a filter for reducing the number of incorrect predic- tions.
Abstract: The objective of the present study was to map dominant plant communities of an alpine area in the northeast- ern Alps (Austria), based on computer modelling. We em- ployed gradient analysis by means of Canonical Correspond- ence Analysis (CCA) as a prediction tool and image segmen- tation as a filter for reducing the number of incorrect predic- tions. Topographical variables reflecting relief properties at different scales were used as surrogates for environmental conditions in combination with spectral band values from infrared orthophotographs. Coupling topographic correlation using CCA and image analysis proved practicable to map the distribution of alpine plant communities. Although plant com- munities often showed similar spectral response, they were mapped according to their specific topographical niches. Gen- erally, topographic variables, indicative of environmental gra- dients controlling plant distribution, provided this information in most cases. The importance of spectral vs topographic variables varied among plant communities. Whereas the cor- relation between topography and plant species distribution was particularly significant for mapping alpine grasslands, spectral texture measures proved to be of major importance in discriminating between pioneer communities. Post-process- ing by image segmentation improved overall accuracy by 12%. A total of 17 plant communities and their mosaics were mapped, with an overall accuracy of 69.4% and a κ value of 0.64. Inaccuracy resulted from insufficient resolution of the available digital elevation model and confounding effects of additional controls like land use history, which could not be accounted for by topographic descriptors.
TL;DR: Spread of the hypovirus was more frequent within treated Sprout clusters than between sprout clusters, and both the nuclear and mitochondrial genomes of the introduced strain persisted in the treated cankers but did not spread beyond them.
Abstract: Biological control of plant diseases generally requires release of living organisms into the environment. Cryphonectria hypoviruses function as biological control agents for the chestnut blight fungus, Cryphonectria parasitica, and hypovirus-infected C. parasitica strains can be used to treat infected trees. We used naturally occurring molecular marker polymorphisms to examine the persistence and dissemination of the three genomes of a hypovirus-infected C. parasitica strain, namely, the double-stranded RNA genome of Cryphonectria hypovirus 1 (CHV1) and the nuclear and mitochondrial genomes of its fungal host. The hypovirus-infected strain was experimentally introduced into a blight-infested chestnut coppice forest by treating 73 of 246 chestnut blight cankers. Two years after introduction, the hypovirus had disseminated to 36% of the untreated cankers and to 35% of the newly established cankers. Spread of the hypovirus was more frequent within treated sprout clusters than between sprout clusters. Mitochondrial DNA of the introduced fungus also was transferred into the resident C. parasitica population. Concomitant transfer of both the introduced hypovirus and mitochondrial DNA was detected in almost one-half of the treated cankers analyzed. The introduced mitochondrial DNA haplotype also was found in three resident isolates from newly established cankers. The nuclear genome of the introduced strain persisted in the treated cankers but did not spread beyond them.
TL;DR: Evaluation of the results indicated a large variability among the teams and call for adequate training of the observers prior to symptom assessment for quality assurance purposes.
TL;DR: In this paper, the authors presented the validation of soil moisture and evapotranspiration (ET) simulation during the special observing period (R-SOP) of the Riviera Project (July-November 1999), a sub-project of the Mesoscale Alpine Programme (MAP).
Abstract: . Detailed plot-scale observations of basic hydrometeorological variables represent valuable data for assessing the quality of the soil moisture module and evapotranspiration scheme in hydrological models. This study presents the validation of soil moisture and evapotranspiration (ET) simulation during the special observing period (R-SOP) of the Riviera Project (July–November 1999), a sub-project of the Mesoscale Alpine Programme (MAP). The location investigated was a sandy soil plot at the edge of a corn field. The hydrological model PREVAH was driven using three meteorological data sets: hourly data from an experimental tower in the Riviera Valley (southern Switzerland), hourly data interpolated for the Riviera site during the R-SOP period from permanent automatic stations (MeteoSwiss network) and interpolated daily data (1980–2000). The quality of the interpolated meteorological data was evaluated with respect to data collected at an experimental tower. The interpolated data proved fairly representative for the location under investigation. The hydrological simulations were compared with recorded observations of soil moisture and latent heat flux (LE). The simulation of soil moisture was accurate in case of all three meteorological data sets. The results of ET simulations with three simple parameterisations showed high correlation to LE derived using the Bowen ratio and measured through eddy correlation. The quantitative agreement between observed and simulated LE was poorer because of the presence of a fully developed wind valley system during periods of good weather. This wind system claims part of the available energy and therefore reduces the amount of energy available for LE. The 21-year simulation at daily time step shows that the R-SOP period in 1999 was warm and wet compared to the last 21 years. Keywords: MAP-Riviera Project, soil moisture, evapotranspiration, hydrological modelling, model evaluation
TL;DR: A field experiment to test various management practices of sustainable forestry was conducted in a Swiss spruce forest for two growing seasons as discussed by the authors, where samples were taken on a 5 × 5 m grid once a year with a soil corer to determine fine root biomass and soil pH of the topsoil.
Abstract: A field experiment to test various management practices of sustainable forestry was conducted in a Swiss spruce forest for two growing seasons. Treatments were a control (C), yearly application of 4000 kg ha−1 wood ash (A), daily irrigation with a steady state fertilisation as ‘optimal nutrition’ (F) and irrigation with a water control (W). Samples were taken on a 5 × 5 m grid once a year with a soil corer to determine fine root biomass (≤ 2 mm) and soil pH of the topsoil. A subset of the fine root samples was further analysed for its nutrient composition by CN and ICP-AES analyses. The dynamics of root growth were observed with the aid of ingrowth-cores after 1, 1.5, and 2 years of treatment and the growth pattern was analysed in terms of biomass, tips, forks, length and root diameter of the samples. The A, F and also the W treatment resulted in a significant increase of soil pH in the topsoil. The fine root density increased over the two growing seasons, irrespective of the treatment. The root growth was only slightly different between the treatments with a initially faster growth under the A treatment. The W treatment reduced the number of root tips and forks, and the root length, while the A treatment increased the number of root tips, forks and the root length, but reduced the diameter. The differences between the three harvesting times (March 1999, October 1999, March 2000) of the ingrowth-cores stressed seasonal differences in root growth and the development of quasi ‘steady state’ root dynamics. The root turnover was not changed by the treatments. The elements in the fine roots were strongly affected by the treatments A and F and sometimes by W. Fine root N increased with the F treatment, while C concentrations decreased under the A, F and W treatments. The Ca and Mg concentrations were strongly enhanced by A but also by the F treatment. The K and P concentrations in the fine roots were improved by all three applications. Due to the pH increase Al, Fe and Mn concentrations in the fine roots were decreased by the A and F treatments. S and Zn concentrations showed inconsistent changes over the growing seasons. The results of this study were comparable with those of other studies in Europe and confirm the abilities of the fine roots as indicators of forest nutrition, to some extent more sensitive than the commonly used foliar analysis.
TL;DR: The study demonstrates that the soil is a major determinant of plant responses to environmental changes, and that intraspecific differences in growth-sensitivity to CO2 or N are considerable, especially on fertile soils, and in the longer term, such differences could alter genotypic composition of temperate forest communities.
TL;DR: On the basis of flora and vegetation data bases, the phenomenon of calcicole richness is tested by analyzing the forest vegetation and the flora of Switzerland and found corresponding patterns and questions several assumptions, e.g. the time considered before the Pleistocene bottleneck, the area considered for speciation/extinction, and the role of habitat diversity rather than two substrate classes.
Abstract: The study of the disparity concerning the sizes of calcicole and calcifuge floras in Central Europe is a surprisingly young scientific branch. Accordingly, explanations of the patterns have not yet been consolidated. In this paper, we comment on the solution of the “calcareous riddle’ proposed by JorgEwald (Folia Geobot. 38: 357–366, 2003). On the basis of flora and vegetation data bases, we tested the phenomenon of calcicole richness by analyzing the forest vegetation and the flora of Switzerland and found corresponding patterns. A clear overbalance of calcareous forest habitats contrasts with an overbalance of acidic topsoils, as derived from a large representative sample in Swiss forests. Calcicole/calcifuge ratios reveal an overbalance of calcicoles in most mapping units of the distribution atlas of vascular plants in Switzerland. Central crystalline parts of the Alps, however, show a clear overbalance of calcifuges. Patterns from the different community and regional scales are explained by (micro-)habitat diversity. With respect to the “calcareous riddle”, we question several assumptions, e.g. the time considered before the Pleistocene bottleneck, the area considered for speciation/extinction, and the role of habitat diversity rather than two substrate classes.
TL;DR: In this paper, the authors verglichen historische (1957) and aktuelle (2001/02) Daten of 19 Bestanden, welche zu drei verschiedenen Bestandestypen gehoren: Bergfohre, „Mischbestand“ and „Arve“.
Abstract: Die traditionelle land- und forstwirtschaftliche Nutzung durfte im Alpenraum in der naheren Zukunft wirtschaftlich bedingt immer haufiger aufgegeben werden. Dieser Trend wird mit groser Wahrscheinlichkeit die Dynamik von Gebirgsokosystemen und damit das Landschaftsbild stark beeinflussen. Aus diesem Grund stieg in den letzten Jahrzehnten das Interesse, die Sukzession auf nicht mehr bewirtschafteten Flachen zu verstehen. Die Bestandesstruktur und -entwicklung von subalpinen Fichtenwaldern (Picea abies L.) wurde bereits intensiv untersucht; uber Entwicklungsprozesse in zentralalpinen Bergfohren- (Pinus montana Miller) und Arven-/Larchenwalder (Pinus cembra L./Larix decidua L.) ist hingegen nur wenig bekannt. Der seit 1914 vom Menschen nur noch touristisch genutzte Schweizerische Nationalpark (SNP) ist eines der wenigen Gebiete in Westeuropa, welches uber langere Zeit nicht bewirtschaftet wurde. Der Park bietet daher die einzigartige Moglichkeit, die Veranderungen in Bestandesstruktur und -zusammensetzung nach Bewirtschaftungsaufgabe zu beobachten. Wir verglichen historische (1957) und aktuelle (2001/02) Daten von 19 Bestanden, welche zu drei verschiedenen Bestandestypen gehoren: „Bergfohre“, „Mischbestand“ und „Arve“. In den letzten 45 Jahren nahm die totale Stammzahl in allen drei Bestandestypen um 45 bis 57% und die Jungbaumzahl pro Hektar um 64 bis 76% signifikant ab, was vor allem auf den starken Ruckgang der lichtbedurftigen Bergfohre zuruckzufuhren ist. Parallel zu dieser Entwicklung, nahm die Menge an liegendem Totholz in allen Bestandestypen von weniger als 4 t/ha auf 36 bis 67,7 t/ha zu, wahrend die Anzahl toter Baume pro Hektar um 72 bis 94% abnahm. Die Biomasse des stehenden Totholzes (t/ha) hat sich hingegen nur leicht verandert. Unsere Resultate beschreiben die sukzessionale Entwicklung von subalpinen Waldern der Zentralalpen und zeigen, wie sich Walder in ahnlichen Berggebieten in der nahen Zukunft entwickeln konnten.
TL;DR: It is suggested that the causal agents in cyclic insect population dynamics should be clarified by field experimentation, since trophic interactions are complex and are further modified by abiotic factors such as climate.
Abstract: The mast depression hypothesis has been put forward to explain the 9- to 10-year population cycle of the autumnal moth (Epirrita autumnata; Lepidoptera: Geometridae) in northern Fennoscandia. We analysed long-term data from Finnish Lapland in order to evaluate the critical assumption of the mast depression hypothesis: that better individual performance of herbivores, followed by high annual growth rate of populations, occurs in the year following mast seeding of the host, the mountain birch (Betula pubescens ssp. czerepanovii). Since mast seeding has been suggested to occur at the expense of chemical defence against herbivores, we bioassayed the quality of birch leaves from the same trees by means of yearly growth trials with autumnal moth larvae. We also measured the size of wild adults as a determinant of potential fecundity of the species in different years. The relative growth rate of larvae was poorer in post-mast years compared to other years, rather than better as assumed by the hypothesis. Conversely, a slight indication of the increase in potential fecundity was observed due to the somewhat larger adult size in post-mast years. Population growth rate estimates, however, showed that the increase in fecundity would have to be much higher to facilitate population increase towards a cyclic peak with outbreak density. Accordingly, our two data sets do not support the assumption of a higher annual growth rate in autumnal moth populations subsequent to mast seeding of the host, thereby contradicting the predictions of the mast depression hypothesis. Temperatures, when indexed by the North Atlantic Oscillation and accumulated thermal sums, were observed to correlate with the abundance or rate of population change of the autumnal moth. The factors underlying the regular population cycles of the autumnal moth, however, remain unidentified. Overall, we suggest that the causal agents in cyclic insect population dynamics should be clarified by field experimentation, since trophic interactions are complex and are further modified by abiotic factors such as climate.
TL;DR: CROCO can provide more consistent and less variable estimates of crown transparency than visual assessments and that it can serve as a reference to detect differences in visual transparency assessments between countries over time.
Abstract: Estimates of crown transparency calculated using the semi-automatic image analysis system CROCO were compared with the visual estimates of survey teams from 12 European countries. For each of five European species (Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.), Scots pine (Pinus sylvestris L.), beech (Fagus sylvatica L.), oak (Quercus robur L.)) 15 trees were assessed. In 64% of the comparisons, CROCO estimates and the survey teams' scores differed significantly, while differences between countries were significant in 58% of all comparisons. We calculated Spearman's rank correlation and the standard deviation of the differences between CROCO and each country and between pairs of countries. We then computed the medians for CROCO and each country. CROCO and only a few countries had for all species a higher median correlation and lower median standard deviation than the median for the comparison between countries. In addition no country had a consistently higher correlation or lower standard deviation than CROCO. We conclude that CROCO can provide more consistent and less variable estimates of crown transparency than visual assessments and that it can serve as a reference to detect differences in visual transparency assessments between countries over time.
TL;DR: In this paper, the authors show that spruce seedlings are able to mobilize and take up Al from solid phases, even under conditions of very low bulk-soil solution concentrations of Al.
Abstract: The usual way to evaluate Al toxicity in forest ecosystems is to consider the concentration of Al 3+ in soil solution. The objective of this paper is to show that Al may affect tree seedlings even under conditions of very low bulk-soil solution concentrations of Al. Picea abies (L.) H. Karst. seedlings, with or without ectomycorrhizal inoculation [Hebeloma crustuliniforme (Bull.: St. Amans) Quel.], were grown in perlite substrate with addition of 0, 0.1, and 0.5 mM Al. The perlite buffered the pH at values > 5 and no soluble Al was detected in the system. However, plant biomass was significantly reduced when 0.5 mM Al was added without fungal inoculation, and Al uptake was 2 to 3 times higher than in the control treatment. Fungal inoculation compensated the growth reduction, but did not reduce Al uptake. These results indicate that spruce seedlings are able to mobilize and take up Al from solid phases.
TL;DR: In this article, the authors investigated short-term 15NO3 uptake by Norway spruce roots after tracer application both in the field and in the laboratory and found that the 15N enrichment in fine roots was not affected by wood ash and liquid fertiliser treatments applied in the previous year.
Abstract: Short-term N uptake by Norway spruce roots was investigated after tracer application both in the field and in the laboratory. In the forest the influence of wood ash or liquid fertiliser treatments on the uptake was studied. A rapid uptake of the 15NH415NO3 tracer into the fine roots was observed. Within 1 day of application about 50% of the maximum δ15N value observed was measured and within 1 week as much as 70–90%. The 15N enrichment in fine roots was not affected by wood ash and liquid fertiliser treatments applied in the previous year. δ15Ν increased continuously until 2 months after 15N application and decreased to 60% of its maximum value within 1 year. Nine months after the tracer application, an analysis of δ15N distribution throughout the root system was conducted. The δ15N values were highest in roots of the topsoil compared to roots at deeper soil layers, and higher in fine roots than in larger roots. The 15N was not translocated within the root system. The laboratory experiment, using Norway spruce seedlings, aimed at describing short-term 15NO3 uptake and assimilation into free amino acids with 2 mM or 20 mM nitrate application. The 15N was detected within 4 h to 1 day in the amino acids Glu, Gln, Asp of roots, while in Asn, Ala and Ser and in the shoots, the 15N was retrieved at the earliest after 1 day. The enrichment factor in the amino acids increased to a maximum within 3–7 days, depending on the nitrate concentration applied.
01 Jan 2003
TL;DR: In this article, the potential of sample surveys to produce estimates of some aspects of the fragmentation status of a landscape, where forest and non-forest are used as example classes, is discussed.
Abstract: Ecosystem fragmentation is being recognized as an important characteristic of landscapes, with numerous implications on its ecological and socio-economic valuation, and for the sustainable management of forest and natural resources in general. Particularly in regions where the population pressure on natural resources is heavy, and where the natural and man-influenced ecosystems are highly vulnerable, monitoring of landscape pattern provides valuable insight in and indicators of ecological landscape development. Pattern is a relatively complicated and multi-dimensional characteristic of landscape. Among the constituting agents are number of vegetation classes considered, number, size, shape, and relative and absolute spatial arrangement of the single patches, as is the scale (spatial resolution, level of detail) with which the landscape pattern is analysed. If an analysis shall go beyond a merely narrative and descriptive approach, indexes are frequently employed to quantitatively characterize the landscape pattern. These indexes are calculated from one or more measurable attributes. Usually, those indexes are derived on the basis of complete maps produced from remote sensing imagery and GIS analysis, and assuming that segmentation and classification of the imagery has been made with a high level of accuracy. Relatively little has been published on how to possibly estimate landscape pattern from sample surveys. This paper discusses the potential of sample surveys to produce estimates of some aspects of the fragmentation status of a landscape, where forest and non-forest are used as example classes. Sample based indexes can be derived from different sampling and plot designs, where area and perimeter length are attributes that can most easily be estimated. However, not all attributes interesting for landscape pattern description can be estimated from samples. We present a method that gives a metric, which is related to mean patch size. Sample-based approaches have some interesting properties: some analysis of pattern can be done in the absence of complete maps, and also for historic inventory data, when neither maps nor imagery are available. The proposed analysis of estimating a mean patch size related metric could easily be done with common forest inventory plot designs, where no additional measurements are required. This may make it interesting for “time series” using old forest inventory data.
TL;DR: In this article, a 3D model derived from the logistic equation for estimating vegetation change, using native and non-native plant diversity, was proposed, which can be used directly for cross-scale evaluations of vegetation data, and indirectly for estimating ecosystem or environmental change.
Abstract: Plant diversity is used as an indicator of the well-being of vegetation and ecological systems. Human activities and global change drive vegetation change in composition and competition of species through plant invasions and replacement of existing species on a given scale. However, species diversity indices do not consider the effects of invasions on the diversity value and on the functions of ecosystems. On the other hand, the existing methods for diversity index can not be used directly for cross-scale evaluation of vegetation data. Therefore, we proposed a 3-dimensional model derived from the logistic equation for estimating vegetation change, using native and non-native plant diversity. The two variables, based on the current and the theoretical maximum diversity of native plants on a given scale, and the result of the model are relative values without units, and are therefore scale-independent. Hence, this method developed can be used directly for cross-scale evaluations of vegetation data, and indirectly for estimating ecosystem or environmental change.
TL;DR: The second IUFRO 7.04.00 report in this series emanating from concurrent sessions held during the 20th International Meeting for Specialists in Effects of Air Pollution on Forest Ecosystems “Air Pollution, Global Change and Forests in the New Millennium” follows as mentioned in this paper.
Abstract: The IUFRO Research Group 7.04.00 “Impacts of Air Pollutants on Forest Ecosystems” in 1998 adopted, as one of its outputs from biennial international meetings, production of a series of general statements [Percy, et al., 1999, Water Air Soil Pollut. 116, 443–448] on the state of science from each of its Working Parties (WP). These discipline-oriented WP have continued to evolve in focus in tune with emerging issues and overall international research direction. The second IUFRO 7.04.00 report in this series emanating from concurrent sessions held during the 20th International Meeting for Specialists in Effects of Air Pollution on Forest Ecosystems “Air Pollution, Global Change and Forests in the New Millennium” follows.
TL;DR: In this paper, the development of the stem numbers, standing volume, increment, utilisation, diameter distribution, diameter class proportions and other parameters relevant to growth and yield are shown, interpreted and compared with the research area Hasliwald in Oppligen.
Abstract: Dursruti is an example for an extreme variation of a selection forest that is characterised by its very high standing volume over a long period of time. Dursruti is also a part of Swiss forestry history: timber marking of the famous thick silver firs, of which only one remains, was reserved for high officials from the federal administration and from research institutions. Dursruti has been a research area of the growth and yield research since 1914. The development of the stem numbers, standing volume, increment, utilisation, diameter distribution, diameter class proportions and other parameters relevant to growth and yield are shown, interpreted and compared with the research area Hasliwald in Oppligen. The tree giants in the Dursruti forest are also examined. The features of this forest as a selection forest are compared with models according to MEYER (1933) and SCHUTZ (1975, 1999). Dursruti forest has undergone a dramatic change in the last decades, which is expressed in the sharp decrease of the stand...