Nitrogen enrichment and warming shift community functional composition via distinct mechanisms: the role of intraspecific trait variability and species turnover

1. Global change factors may shift community functional composition by driving species turnover (species occurrence and species relative abundance) and intraspecific trait variability. However, their relative contribution in determining the functional response of community to global change, especially nitrogen enrichment and warming, remains unclear.

2. We conducted a fully factorial field experiment in a Tibetan alpine meadow to examine responses of plant community functional composition to nitrogen enrichment and warming by quantifying seven plant functional traits in each plot. Using the sum of squares decomposition, we further disentangled the relative contribution of intraspecific trait variability and species turnover to changes in community functional composition.

3. We found that nitrogen enrichment caused a shift of plant community toward a more resource-acquisitive strategy, while warming resulted in a shift toward a more resource-conservative strategy. Plant intraspecif...