Disentangling the influence of local and landscape factors on alpha and beta diversities: opposite response of plants and ground-dwelling arthropods in wet meadows

摘要

A large number of studies have tried to understand the determinants of local species richness, i.e. alpha-diversity. Studies dealing with beta-diversity are considerably less numerous but their number has increased in the recent years. In this study, we assessed the relative importance of local and landscape (i.e. composition and connectivity) variables in explaining alpha- and beta-diversities (species turnover and nestedness) of three highly diverse groups, differing in mobility and dispersal: plants, spiders, and carabids. Sampling took place in 2013, using suction samplers for arthropods and phytosociological relev,s for vegetation, in 77 hay meadows distributed along 200 km of the Loire Valley (France). We found plant alpha-diversity to be driven by local factors, whereas spider and carabid alpha-diversities were mostly determined by landscape factors (by composition and connectivity, respectively). Nestedness was negligible for the three groups. Plant beta-diversity was also mainly influenced by local factors, whereas spider beta-diversity was driven by landscape factors (composition and connectivity, equally). Surprisingly, carabid beta-diversity was mainly influenced by local factors and landscape connectivity. Despite these differences, plant, spider, and carabid beta-diversities were not different, suggesting comparable dispersal abilities and/or a low connectivity at large scale, which is in accordance with the high species turnover observed here. Managing biodiversity in meadows consequently necessitates acting at local and landscape scales, the first targeting plants and the second arthropods.