Authors: Wersebeckmann, Vera; Entling, Martin H.;Leyer, Ilona;

Viticulture on steep slopes has shaped both landscape and biodiversity in wine growing regions. However, viticultural area suffered strong declines in recent decades due to insufficient profitability. A solution to reduce further abandonment and maintain cultivation economically viable could be vineyard terracing. However, little is known about the effects of vineyard abandonment and a change of vineyard management type on biodiversity.
We determined the effects of vineyard management types in contrast to vineyard fallows, local conditions and the surrounding landscape on wild bee diversity in 45 study sites along the Upper Middle Rhine Valley in Germany. Alongside the Rhine environmental conditions altered slightly i.e. soil shifted from fertile loess to schistose soils which in turn was correlated with increased vineyard abandonment.
Although floral resources were higher in managed vineyards, overall wild bee species richness was highest in vineyard fallows. Ground-nesting bees decreased alongside the Rhine with altering site, especially soil conditions irrespective of vineyard types. In contrast, above-ground nesting bees showed stronger responses to vineyard management and were more closely associated with vineyard fallows. Our results show that suitable nesting conditions rather than floral resources structured wild bee communities. Therefore, conservation efforts need to consider both foraging and nesting requirements.