Browsing by Subject "Hecke"

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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.