Browsing by Subject "Functional diversity"

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Effects of land-use intensity on functional community composition and nutrient dynamics in grassland
(2024) Walter, Julia; Thumm, Ulrich; Buchmann, Carsten M.; Heinonen-Tanski, Helvi
Land-use intensity drives productivity and ecosystem functions in grassland. The effects of long-term land-use intensification on plant functional community composition and its direct and indirect linkages to processes of nutrient cycling are largely unknown. We manipulated mowing frequency and nitrogen inputs in an experiment in temperate grassland over ten years. We assessed changes in species composition and calculated functional diversity (FDis) and community weighted mean (CWM) traits of specific leaf area (SLA), leaf dry matter content (LDMC) and leaf and root nitrogen of the plant community, using species-specific trait values derived from databases. We assessed above- and belowground decomposition and soil respiration. Plant diversity strongly decreased with increasing land-use intensity. CWM leaf nitrogen and SLA decreased, while CWM LDMC increased with land-use intensification, which could be linked to an increased proportion of graminoid species. Belowground processes were largely unaffected by land-use intensity. Land use affected aboveground litter composition directly and indirectly via community composition. Mowing frequency, and not a land-use index combining mowing frequency and fertilization, explained most of the variation in litter decomposition. Our results show that land-use intensification not only reduces plant diversity, but that these changes also affect nutrient dynamics.
Increases in functional diversity of mountain plant communities is mainly driven by species turnover under climate change
(2023) Schuchardt, Max A.; Berauer, Bernd J.; Duc, Anh Le; Ingrisch, Johannes; Niu, Yujie; Bahn, Michael; Jentsch, Anke
Warming in mountain regions is projected to be three times faster than the global average. Pronounced climate change will likely lead to species reshuffling in mountain plant communities and consequently change ecosystem resilience and functioning. Yet, little is known about the role of inter‐ versus intraspecific changes of plant traits and their consequences for functional richness and evenness of mountain plant communities under climate change. We performed a downslope translocation experiment of intact plant‐soil mesocosms from an alpine pasture and a subalpine grassland in the Swiss and Austrian Alps to simulate an abrupt shift in climate and removal of dispersal barriers. Translocated plant communities experienced warmer and dryer climatic conditions. We found a considerable shift from resource conservative to resource acquisitive leaf‐economy in the two climate change scenarios. However, shifts in leaf‐economy were mainly attributable to species turnover, namely colonization by novel lowland species with trait expressions for a wider range of resource use. We also found an increase in vegetative height of the warmed and drought‐affected alpine plant community, while trait plasticity to warming and drought was limited to few graminoid species of the subalpine plant community. Our results highlight the contrast between the strong competitive potential of novel lowland species in quickly occupying available niche space and native species' lack of both the intraspecific trait variability and the plant functional trait expressions needed to increase functional richness under warming and drought. This is particularly important for the trailing range of many mountain species (i.e. subalpine zone) where upward moving lowland species are becoming more abundant and abiotic climate stressors are likely to become more frequent in the near future. Our study emphasizes mountain plant communities' vulnerability to novel climates and biotic interactions under climate change and highlights graminoid species as potential winners of a warmer and dryer future. Keywords: alpine grassland, functional diversity, invasion, species turnover, traitspace, translocation
Laufkäfer(Col., Carabidae) in Feldhecken Südwestdeutschlands : Vergesellschaftung und Biodiversität in Abhängigkeit von der Habitatqualität
(2013) Theves, Florian; Zebitz, Claus P. W.
The drastic decline of species caused by intensification of farming in the long run reduces the flexibility and productivity of our agroecosystems. One possibility to counter this negative development is the preservation of typical local species compositions in anthropogenic cultivated ecosystems. The conservation of valuable, or the creation of new habitat patches is a way to maintain these requirements. So far, there is too little knowledge yet, which habitat traits are most important for a given group of organisms. As the habitat requirements of many species vary on a regional level, it is necessary to categorize biotopes into types as a precondition for the application of those types on a broader scale. In this study, the zoo-ecological value of hedgerows is categorized by using ground beetles (Carabidae). Using the ?Filderebene? south of Stuttgart as an example, multivariate methods were used to distinguish general types of hedgerows to which regional bioindicators are assigned. Furthermore, the components of ground beetle diversity in hedges are investigated on different spatial scales and a method to estimate functional diversity is tested. It has been demonstrated that hedgerow types can be distinguished by a gradient of ground area size and age. Each of these types contain specific species, suitable for differentiation, established by calculation of species-associatons and indicator-analyses. While richness in species and individuals alone shows no clear dependency, especially forest carabids were positively correlated with hedgerow size. Besides, species-accumulation-curves show that few large hedges contain more species than small ones. Furthermore, it could be proven, that the carabid beetle associations are not only affected by the factors size and age, but also by the coverage of herbaceous vegetation and zonation of the hedgerows. The biodiversity components show a dependency on hedgerow size, too. While alpha-diversity per hedge increases significantly with decreasing area, beta-diversity decreases simultaneously. This relationship can be explained by the immigration of field species into the small hedges, whereas large and old hedges have a greater variety in structure, which results in a large number of microhabitats occupied by carabids. On site-level, the large hedges showed a higher alpha- and gamma-diversity than small hedges, which can be attributed to a higher general species richness of sites with extended hedgerows. In small hedges, biodiversity depends on the surrounding crops, whereas carabid beetle associations of large hedges are less affected by bordering habitats. This was evident, because homogenization of the surrounding crops caused a decline of alpha-diversity and an increase of beta-diversity in the hedges. A comparison between beta-diversities at site- vs. hedgerow-level shows higher heterogeneities inside than between hedges. In order to consider the functional component of biodiversity as well, the carabids of the hedgerows were partitioned into functional groups (guilds) by means of cluster-analysis based on their morphological and ecological traits. The number of guilds in a hedgerow can be used as an estimate for its functional diversity and efficacy of resource use. The average number of three guilds per hedge varies with hedgerow size and age. This results in a shift of species composition of carabid guilds based on hedgerow type and the continuity, of the functional groups occurence during the investigation period. In smaller hedges, the guild of ?forest species? is substituted by less specialized field species and the number of different significant guilds is less stable than in larger hedges.