Unravelling the effects of vineyard inter-row vegetation on soil biodiversity in South Africa

For sustainable viticulture it is suggested that farmers maintain vegetation cover in inter-rows to promote ecological balance. However, the extent to which inter-row vegetation influence soil biodiversity and associated ecosystem functions remains an open question. This study explored how different vineyard inter-row vegetation management practices influence soil fauna diversity, composition and functional structure. The research was conducted across 24 sites in the Stellenbosch area, Western Cape, South Africa. Three treatments were compared: bare (no vegetation), covered (vegetation allowed to grow), and natural (natural fynbos vegetation outside of the crop areas). Natural vegetation and covered vineyards had significantly higher species diversity and proportion of detritivores compared to bare vineyards. Vegetation cover had a positive influence on soil fauna diversity, particularly for spiders, and functional groups such as detritivores, omnivores, and predators. However, herbivores were negatively affected by vegetation cover, suggesting that vineyards with higher vegetation cover may have fewer herbivores. Litter cover was the primary variable influencing soil fauna diversity and composition, highlighting the importance of retaining organic matter in vineyards. The study also shows that plant species richness had a negative impact on ant species diversity, possibly due to increased competition for resources. In contrast, spiders were positively affected by litter cover, which may have facilitated prey trapping and reduced soil disturbance. The findings of this study emphasize the significance of vegetation management in maintaining soil fauna diversity and composition in vineyards. The results suggest that covered vineyards can support a more diverse range of soil fauna, which can contribute to ecosystem services. Overall, this study highlights the importance of adopting sustainable vineyard management practices that prioritize soil fauna conservation and biodiversity.