Several studies indicate detrimental effects of land-use intensification on arthropod diversity and linked ecosystem functions. Most empirical studies, however, focused solely on grasslands or local approaches limited generalizations. Large-scale studies are still missing, especially in forests. In the present study, conducted within the Biodiversity Exploratories Project, we investigated effects of land-use intensity in forests and grasslands in a large scale approach, including 3 regions in Germany (Schorfheide-Chorin, Hainich-Dün, Schwäbische Alb), 100 plots per region representing different land-use forms, and different forest (forest floor, understorey, canopy) and grassland (ground, vegetation) strata. We hypothesis that 1) increasing land-use intensity decreases species and functional diversity in forests and grasslands. 2) effects of land-use depend on habitat type (forest, grassland), region and strata. Arthropods were sampled by pit-fall traps and flight-interception traps (understorey, canopy) in the forest and pit-fall traps and sweep-netting in the grasslands during the whole vegetation period (April-October) in 2008.
Results/Conclusions
Preliminary results clearly indicate that effects of land-use indeed depend on habitat type, taxa, ecological guilds, stratum and region. Overall, the hypothesis of a higher arthropod diversity in natural habitats could not be supported by our results. In forests we found, for example, some indication for a higher diversity of different functional groups (e.g. predatory spiders, plant sap sucking true bugs) in unnatural conifer forests compared to natural beech forests. On the other hand, for herbivorous and saproxylic beetles diversity was highest in natural forests, but only in one region (Schwäbische Alb). In grasslands, diversity of some herbivores (Saltatoria, Auchenorrhyncha, Heteroptera) decreased with increasing land-use intensity, but in each case only in one region. Results show that we have to be very cautious in generalizing data based on data limited in spatial (and probably in temporal) scales, habitats and target groups. We need more sophisticated analyses including ß-diversity, food web structures, body-size relationships and functional diversity analyses. Moreover it seems to be necessary to link arthropod data to a finer or ideally continuous scale of management intensity to enable more detailed insights on land-use effects.
