Willow trees planted in a vineyard: what is the effect on microclimate, vine physiology and soil?

Summary

Introduction
Climate change poses major challenges for viticulture through rising temperatures, more frequent heat waves, and prolonged drought periods. These changes can affect grapevine physiology, berry composition, and ultimately wine quality. In response, winegrowers are increasingly exploring innovative and sustainable strategies to enhance the resilience of vineyards. One approach is vitiforestry, the integration of trees within vineyards. Planting trees within vineyards has emerged as a potential strategy to mitigate climate change associated risk by modifying vineyard functioning in several ways. Through shading and evapotranspiration, tree could modify the microclimate, potentially reducing canopy temperature. They may also affect vine water relations by altering soil moisture dynamics. In addition, the presence of trees can contribute to improved soil structure, enhanced nutrient cycling, and increased soil biodiversity.
Methodology
This study investigated the effects of trees on vine performance and soil chemistry in an established vitiforestry system planted in 2012 in Bremblens, western Switzerland, consisting of 70 grapevine rows interspersed with 18 willow trees (Salix sp.) arranged in two rows 20 m apart. To examine the effect of the trees on soil chemistry, soil samples were collected at the rootstock and in the alley of two rows with trees and two rows without trees at two depths (Figure 1). In addition, roots and rhizosphere samples were collected to characterize the microbiome. Building on previous work on arbuscular mycorrhizal fungi (Bodenhausen et al., 2025) , the present study characterized the entire fungal community using full-length ITS metabarcoding and PacBio sequencing.
Results
Results on microclimate, water availability, productivity and berry quality were shown at EURAF 2024. Soil chemical properties were mainly determined by soil depth, with topsoil and subsoil clearly differing in nutrient composition, while slope position had a weaker effect. Topsoil contained significantly higher boron and copper concentrations, with boron accumulating downslope and copper concentrations reflecting long-term fungicide use. The presence of willow trees significantly reduced copper concentrations in nearby vine soils, particularly in the rootstock zone, suggesting a localized mitigation of copper accumulation.
Conclusions
This study suggests that integrating Salix alba into vineyards can reduce soil copper accumulation and enhance vineyard sustainability, although effects on soil microbial communities were limited and influenced more strongly by environmental factors such as slope position.