Die chronologische Liste zeigt aktuelle Veröffentlichungen aus dem Forschungsbetrieb der Hochschule Weihenstephan-Triesdorf. Zuständig ist das Zentrum für Forschung und Wissenstransfer (ZFW).
Phytosociology is a subdiscipline of plant ecology that describes the co‐occurrence of plant species in communities. Gradient analysis and classification are its complementary tools. Various peculiarities and anachronisms of Central European phytosociology conceal its similarity with Anglo‐American approaches. Phytosociology deserves to be updated as a part of modern vegetation science that can build on a vast heritage of high‐quality data and the tools to store and analyse them in ways that go beyond syntaxonomy. By providing a context to more specialized pure and applied research, it has a crucial role to play in understanding community structure, ecosystem functioning and biological evolution.
Prof. Dr. Andreas Rothe,
Prof. Dr. Jörg Ewald,
David E. Hibbs
Berechtigungen: Peer Reviewed
Do admixed broadleaves improve foliar nutrient status of conifer tree crops? (2003) Forest Ecology and Management 172 (2-3), S. 327-338.
DOI: 10.1016/S0378-1127(01)00800-3
We investigated three Douglas fir–red alder stands in Oregon, USA, and five Norway spruce–European beech stands in Bavaria, Germany, to test the hypothesis that admixtures of broadleaved trees improve nutritional status of conifers. At each site needle samples from 20 to 30 conifer trees with varying proportions of broadleaves adjacent to the sample trees were taken and analysed for needle mass and the macronutrients N, P, K, Ca and Mg. The neighbourhood of each tree was described by the proportion of deciduous basal area within an 8 m circle. Ordination methods (principal component analysis; redundancy analysis) were used to test the dependency of the multivariate nutritional pattern in conifers on deciduous neighbours and rank correlation and regression were used to analyse bivariate relationships between tree species composition and descriptors of needle status. The statistical analyses yielded no evidence that deciduous admixtures improve foliar nutrition of conifers. Alongside with other empirical studies this shows that beneficial effects of broadleave admixtures on conifer nutrition are less common than postulated. Future research investigating the whole causal path relevant for tree nutrition and growth is necessary to improve our knowledge in the complex field of nutrition of mixed species forests.
Prof. Dr. Jörg Ewald
Berechtigungen: Peer Reviewed
The sensitivity of Ellenberg indicator values to the completeness of vegetation relevés (2003) Basic and Applied Ecology 4 (6), S. 507-513.
DOI: 10.1078/1439-1791-00155
Ordination and calibration (indicator species analysis) are based on the taxonomic composition and richness of communities. How strongly does the performance of a widely used method like weighted averaging of Ellenberg indicator values depend on the completeness of samples? Based on a stratified random sample of coincident phytosociological relevés of forest understorey and environmental measurements (overstorey cover, elevation, moisture index, pH and C/N-ratio in topsoil) indicator values for light, temperature, moisture, soil acidity and nitrogen were tested. To simulate reduced sampling effort and uncomplete representation of plant diversity, the original compositional matrix was reduced by randomly deleting 1, 10, 20, 40 and 80% of species records with low abundance. The relationship between indicator values based on the full matrix and environmental variables was closest for temperature (R2 = 0.53) and lowest for soil nitrogen (R2 = 0.28). Deletion of low-abundance species records affected the correlations only weakly. With as little as 20% of the original species records (or 40% of gamma- and 20% of alpha-diversity) explained variance was still in a range of 0.26 to 0.37. The overall multivariate association between species composition and environment, as measured by Mantel statistics, was more strongly affected by the ommission of species records than the Ellenberg method. The relative resilience of Ellenberg indicator values to incomplete sampling is attributed to its predominant reliance on coarse structural information, i.e. the dominance pattern of relatively few plant species. Finely-tuned local indicator systems perform better by exploiting the idiosyncratic information of rare species. Choosing an optimal sampling scale involves a tradeoff between noise and completeness, an issue that has been largely neglected by environment-composition studies.
Prof. Dr. Josef Kainz,
Ulrich Rössler,
R. Winkler
Spin splitting and spin-relaxation rates in semiconductor quantum structures (2002) PASPS, Würzburg, 2002 .
Prof. Dr. Josef Kainz,
Ulrich Rössler,
R. Winkler
Spin splitting and spin-relaxation time in semiconductor heterostructures (2002) 12th International Winter School on New Developments in Solid State Physics, Mauterndorf, Österreich .
Betreuung der Publikationsseiten
Gerhard Radlmayr
Referent für Wissenstransfer und Forschungskommunikation
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