Relating plant species and functional diversity to community δ13C in NE Spain pastures

The relationship of plant species and functional diversities to community-level δ13C, as a proxy for water carbon relations, was assessed in pastures from two climatic regions in NE Spain. Overall, community δ13C was negatively related to species diversity, but positively related to functional diversity. However, pronounced differences between climatic regions were found: smaller variations in δ13C and thus carbon–water relations were observed for communities under humid conditions, which had higher species diversity but were more functionally redundant than communities under arid conditions. Thus, if species and functional diversities affect plant carbon–water relations at the community and hence at the ecosystem level seems to depend strongly on functional redundancy, i.e., the overlap in plant traits among the species present.