Grassland degradation alters the effect of nitrogen enrichment on the multidimensional stability of plant community productivity.
Abstract
Nitrogen (N) enrichment threatens the ability of grasslands to support sustainable functions. However, we do not know whether grassland degradation can alter the effect of N enrichment on the multidimensional stability of plant community productivity. Using data from N enrichment experiments at temperate grassland sites (no, moderate and severe degradation) that experienced a flooding event, we tested the impact of N enrichment on multidimensional stability (resistance, resilience, recovery and temporal stability) of plant community productivity. In non-degraded and moderately degraded grasslands, N enrichment negatively influenced resistance and temporal stability but positively altered resilience and did not change recovery. Species asynchrony altered all stability dimensions, except for recovery. In severely degraded grasslands, the effects of N enrichment on multidimensional stability shifted. Resilience and recovery were negatively affected by N enrichment, while resistance and temporal stability were not influenced. A decrease in dominant species stability reduced community resilience and recovery in severely degraded grasslands. Synthesis and application. Grassland degradation regulates the effect of N enrichment on the multidimensional stability of plant community productivity. Thus, our findings highlight the need to consider grassland degradation in future studies for a comprehensive understanding of grassland dynamics.