Changes in specific leaf area of dominant plants in temperate grasslands along a 2500-km transect in northern China

Specific leaf area (SLA) is a key trait with great ecological importance as it correlates with whole plant growth. We aimed to investigate how SLA varies with environmental factors at a geographical scale in temperate grasslands. We measured SLA and mass-based leaf nitrogen content (N (mass)) of four dominant plant genera along a 2500 km climatic gradient in northern China grassland, and correlated SLA with mean annual precipitation (MAP), mean annual temperature (MAT), soil nitrogen concentration (soil N), soil C:N and N (mass). Climate accounts much more for SLA variation than soil variables for Stipa, Cleistogens and Carex. SLA of Stipa is negatively associated with MAP and soil N, while positively with MAT, but Cleistogenes and Carex show the opposite. For Leymus, soil N promotes SLA and accounts for largest fraction of SLA variation. Overall, SLA was positively correlated with N (mass) in semi-arid regions, but not significant in arid regions. The genus-dependent responses of SLA may have consequences on ecosystem functioning, thus may help to predict the community composition and ecosystem functions under future climate scenario. The finding of SLA-N (mass) trade-off and its susceptibility to precipitation will advance our understanding on plant resource use strategies.