Abstract:

Studies along environmental gradients have shown that intraspecific trait variation (ITV) may contribute considerably to community-level trait variation. However, we lack knowledge about how the extent of ITV varies on a local scale and whether a varying extent of ITV is related to differences in local environmental site and plant community characteristics.

We investigated plant height, specific leaf area (SLA), leaf dry matter content (LDMC) and leaf greenness of three common grass species (Arrhenatherum elatius, Dactylis glomerata, Poa pratensis) in 12 mown grasslands in a local study area around Jena (Thuringia, Germany) across three spatially hierarchical sampling levels: between sites, between subplots within site and within subplots.

Arrhenatherum elatius and D. glomerata had higher means in plant height and a lower variation in leaf traits than P. pratensis. The major proportions of variation in leaf traits of P. pratensis and D. glomerata were found within subplots, while the traits of A. elatius varied mainly between sites. Trait correlations across the hierarchical sampling levels were highly consistent in A. elatius, but more variable in D. glomerata and P. pratensis. Environmental site and plant community characteristics mostly explained a larger proportion of variation in trait means in A. elatius than in D. glomerata and P. pratensis, while metrics of ITV were generally less predictable. Our results suggest that trait variation in P. pratensis and D. glomerata is more strongly related to within-site conditions (i.e. biotic interactions), while differences in local environmental conditions between sites have a strong impact on trait variation in A. elatius. Since our study was limited to three grass species, further studies with a greater number of species are required to make generalizations about the importance of biotic interactions and environmental conditions as drivers of ITV at local scale.

Key words: grass species, intraspecific trait variation, leaf traits