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Seed, germination and site characteristics: which parameters of arable weeds do explain the change of frequency in Germany?

Summary
For 130 arable weed species occurring in Germany we analysed their combinations of seed, germination and habitat traits by means of Principal Components Analyses. Special attention was paid to species with presently de- or increasing populations. Results did not yield any indication that advantageous strategies like, e. g. a rapid and complete germination of seeds, have a beneficial effect on the present situation of the weed species. Germination rates and the time span needed to reach the peak of germination showed little differentiation between species. Thus, these germination traits are not well suited to explain the success or failure of species. Presently expanding weed species (high ‘tendency of change’-value according to ELLENBERG et al. 1992) were characterised by high optima and wide amplitudes in germination temperature, and high Ellenberg nutrient values.
In general, the tendency of change for arable weeds showed higher correlations with habitat traits (expressed as Ellenberg indicator values) than with seed and germination traits. Expanding species were characterised by high nutrient values, high moisture values and low light values. Remarkably, many species with this combination of traits are considered introduced species in Germany (neophytes). Arable weed species may also profit from modern agronomy with its constant adaptations of cultivation and harvesting practices, which create favourable new site conditions for contemporary crop species. However, our results show that mainly neophytes benefit from modern agriculture, and not the native arable weeds.

german version

Keywords/Stichworte:Arable weeds; seed weight; germination; requirements for germination

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Autor:A. OTTE, S. BISSELS, R. WALDHARDT, Professur für Landschaftsökologie und Landschaftsplanung, Justus-Liebig-Universität Giessen, Heinrich-Buff Ring 26-32, 35392 Giessen, E-Mail: annette.otte@agrar.uni-giessen.de, stephanie.bissels@agrar.uni-giessen.de, rainer.waldhardt@agrar.uni-giessen.de

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