Joseph BOULNOIS, supervised by Ludovic Henneron at the Ecodiv Laboratory (University of Rouen), successfully completed his M2 internship. He conducted sampling and measurements on understory species within the OPTMix and Gis-Coop networks during spring-summer 2025.
Forest stand density influences understory biodiversity and functioning, but the relationships between silvicultural practices and plant functional traits remain little explored. This study, conducted on an experimental network of 24 plots, analyzes the effect of different thinning intensities on the composition, biomass, and leaf traits of understory herbaceous species. Trait measurements (SLA, LDMC, nitrogen content, and average plant height) were performed on several dominant species, including seedlings of Quercus petraea. Results show that canopy opening favors heliophilous species and increases total biomass, while shade-tolerant species decline. Functionally, thinned stands display higher SLA and nitrogen content, indicating a resource-acquisitive strategy that supports growth. However, these patterns vary among species, reflecting high interspecific variability. Stand density thus emerges as a key factor structuring understory communities and their functioning. Silvicultural practices, particularly thinning, therefore represent a potential lever to guide biodiversity dynamics and the resilience of managed forests.
