A multidisciplinary approach to assess the impact of future drought scenarios on vineyard ecosystems

Abstract

Drought events can strongly affect grapevine and berry physiology and subsequent wine quality, as widely demonstrated in controlled experiments. However, the potential impacts of summer drought on the whole vineyard ecosystem, combining vegetation, soil and its microbiota, remains poorly explored, especially in cooler climate regions.

To fill this gap, we set up a multidisciplinary drought simulation experiment in a Chasselas vineyard in Yvorne (Switzerland). Four rainout shelters were installed to prevent natural rainfall in April 2024. Under these shelters, the experimental plots were subjected to three different water supply regimes: 1) a control regime representing the 20-year average local rainfall; 2) a high-water stress regime, based on RCP 8.5 climate projections for 2085; 3) an extreme water stress regime, with water supply reduced to 50% of the 2085 projections. Additionally, an external control was setup for each replicate.

Vine physiology (such as water potential, photosynthesis, δ13C, vigour, fertility, yield), berry composition (organic acids, sugars, amino acids), wine quality, plant species composition, soil properties and soil microbial diversity were monitored throughout the 2024 growing season. These measurements will be repeated in 2025 and 2026. Below and aboveground temperature and humidity are continuously recorded at various heights and depths.

Preliminary results from the first year revealed that the extreme water stress regime reduced vine fertility, berry weight, yield and most assimilable nitrogen by one-third compared to the control treatments. Water stress also altered soil cover composition. In the drought-induced plots, soil cover predominantly consisted of mulch and plant species composition shifted towards more drought-resistant species.

Altogether, this study will deepen our understanding of summer drought impacts on vineyard ecosystems and provide further insights into the interactions between soil, vegetation and vines under different water conditions. This study will also contribute to develop innovative vineyard management practices better suited to future climatic conditions.