Positive effects of organic viticulture on carabid beetles depend on landscape and local habitat conditions

Abstract

Agricultural intensification is a major cause of biodiversity loss. Organic farming may counteract the loss of species, however, knowledge about its benefits for perennial agroecosystems such as vineyards is incomplete. We, therefore, analysed the effects of organic viticulture on carabid beetles, a frequently used indicator group in agroecology. We investigated organic and conventional vineyards in two different landscapes (‘simple’ vs. ‘complex’) in SW Germany using a paired design. As a key result we found positive effects of organic viticulture on carabid diversity only in the simple landscape while such an effect was not obvious in the more complex landscape. Moreover, the species composition was differently influenced by organic management between the two landscapes indicating context-dependent responses of carabid species towards the farming practice. We conclude that positive effects of organic viticulture on carabid beetle diversity differ with landscape context and depend on local habitat conditions such as slope inclination and the inter-row vegetation. Our results therefore indicate that organic viticulture benefits are not only highly variable among taxonomic groups, but can have even varying effects within one insect family.