Tage der Biodiversität 2027

Environmental gradients shape community assembly by constraining the ecological strategies that can persist within plant communities. We investigated how multidimensional community trait space changes with elevation and whether these changes parallel variation in local species richness in alpine pastured grasslands of the Central Eastern Alps, Italy. We quantified abundance-weighted trait space across four elevational bands (1000–2500 m a.s.l.) using Gaussian kernel hypervolumes based on four plant functional traits representing plant size, nutrient requirements, seed production, and dispersal ability. We complemented these analyses with estimates of functional overlap, plot-level regression models, and leave-one-species-out analyses.

Community trait space contracted markedly with increasing elevation, while functional overlap among communities increased, indicating greater similarity in the trait space occupied at higher elevations. In contrast, local species richness increased along the same gradient. Furthermore, a small number of functionally distinctive species contributed disproportionately to maintaining community trait space.

The opposing trends in species richness and trait space suggest stronger environmental filtering and increasing functional convergence with elevation. Our findings demonstrate that taxonomic and functional diversity can follow contrasting patterns along environmental gradients. Multidimensional trait-space analyses may therefore reveal changes in community assembly that species richness alone obscures, while highlighting the importance of functionally distinctive species in maintaining ecological strategies.