Inter-row vegetation benefits soil invertebrates in Mediterranean organic vineyards

In perennial crops, such as vineyards, permanent inter-row vegetation may help to preserve soil fauna and their associated ecological functions. However, vegetation is often removed by tillage to avoid water competition, even though this practice is recognized to be detrimental for soils and biodiversity. The objective of our study is to assess the effects of an intensity gradient of inter-row management on vegetation, soil chemistry and soil invertebrates. Vegetation, soil, and fauna (i.e. springtails, mites and earthworms) were sampled in 25 organic vineyards located in the Luberon (south-eastern of France). Three management practices were considered: fully vegetated vineyards, one out of two inter-rows vegetated, and fully shallow-tilled vineyards. Shallow tillage had limited direct negative effects on Gamasida mites and Symphypleona springtails only. A path analysis revealed that plant cover and diversity had the strongest effects. Earthworm, in particular Lumbricus terrestris abundance, increased with vegetation cover, and earthworm species richness increased with plant diversity. Moreover, an increased plant species richness had a positive effect on soil organic matter and nutrient content which can be, in turn, beneficial to meso- and macrofauna. This study highlights the importance of reducing the intensity of soil tillage in vineyards and of restoring a diverse inter-row vegetation to improve habitat quality and diversity that are crucial for soil organisms and their associated ecological functions.