Terracing in steep slope viticulture and its potential to promote biodiversity in vineyard ecosystems

Abstract

Viticulture on steep slopes has shaped exceptionally species-rich cultural landscapes in Germany. However, the area under vines has declined sharply in recent decades due to insufficient profitability. Vineyard terracing could be a solution to reduce further abandonment and maintain economic viability.

However, little is known about the effects of abandonment and changes in vineyard management on biodiversity. Over a three-year period, we investigated the effects of vineyard management types (vertically oriented vs. terraced), as compared to vineyard abandonment, local conditions and the surrounding landscape on plant, Orthoptera, wild bee and spider diversity at 45 study sites along the Upper Middle Rhine Valley (UMRV) in Germany.

The small-structured landscape of the UMRV supported high species diversity, high numbers of threatened species and diverse species communities across vineyard management types and fallows. Species responses were group and taxon specific and were driven by different management intensities, local vegetation structures and landscape structure. In short, plant and Orthoptera diversity benefited from terraced vineyards with nutrient-poor and extensively managed terraces. Wild bee diversity was determined by their specific nesting needs and was particularly favoured by the woody structures of the fallows, while spiders benefited from high landscape complexity.

In summary, heterogeneous landscapes, including actively managed and abandoned vineyards and natural elements providing complementary resources, were critical to meeting the many specific needs. However, active vineyard management is essential to maintain the characteristic flora and fauna of steep slope viticultural landscapes. Terraced vineyards, especially when revegetated with regional seed mixes, have a high biodiversity potential and can help to combine economically viable steep-slope viticulture with nature conservation objectives in a land-sharing approach.