Helena Vallicrosa (WSL / EPFL), member of the ReCLEAN consortium, presented new experimental findings on how climate extremes shape nitrogen cycling in grasslands during her seminar “The role of plant–soil–microbe interactions on nitrogen cycling under drought and warming in grasslands.” Using a large-scale pot experiment with six grassland species and contrasting soil-management histories, Vallicrosa simulated drought and warming to understand how plants and soil microbes share – or compete for – nitrogen under future climate conditions.

Early results show that drought exerts a far stronger influence than warming, reducing plant productivity and altering microbial nitrogen stocks. The effects also depended on management history: grasslands from extensively managed soils were more resilient, while intensively managed ones showed a shift toward plants becoming net nitrogen sources under stress. Functional group differences further emerged, suggesting that grasses, forbs and nitrogen-fixers coordinate with soil microbes in distinct ways when water becomes limiting.

Vallicrosa highlighted that these interactions are often overlooked in ecosystem models, despite their central role in determining nutrient cycling and grassland resilience. Her work underscores the need to consider soil microbial communities alongside plants when developing climate-adaptation strategies for managed European grasslands.

Watch the seminar here.