The final structural equation models demonstrate that nitrogen addition and mowing change compositional and functional aspects of community resistance (A) and recovery (B) mainly by modulating species asynchrony, the corresponding resistance and recovery of dominant species and grasses.
Newswise — Dr. Zhuwen Xu (Inner Mongolia University, School of Ecology and Environment) oversaw a five-year field experiment at the Erguna Forest-Steppe Ecotone Research Station in Inner Mongolia, China, examining the impact of three-year natural drought (2015-2017), increased nitrogen input, and mowing on the resistance and recovery of temperate grassland. The experiment involved annual implementation of treatments - nitrogen addition (+10 g nitrogen m−2yr−1, N), mowing, and N plus mowing - with natural communities serving as control, receiving no nitrogen addition and no mowing. Throughout the five-year experiment, surveys of plant community's species composition and aboveground biomass were conducted each growing season.
According to the experiment's findings, nitrogen addition led to increased grassland biomass recovery, but reduced structural recovery after drought. Meanwhile, annual mowing increased both grassland biomass recovery and structural recovery, but decreased structural resistance to drought. These results highlight the importance of examining stability at various ecological levels to gain a comprehensive understanding of how human-induced environmental changes impact ecological stability.
The study's authors discovered that the impacts of nitrogen addition and mowing on community biomass, structural resistance, and recovery were primarily influenced by the stability of dominant species and asynchronous dynamics among species. Additionally, the stability of grasses played a significant role in determining community biomass resistance and recovery. These findings emphasize the significance of dominant species and specific plant functional groups, as well as the complementarity effects among species, in determining both the biomass and structural stability of temperate grasslands experiencing drought.
The research offers significant evidence regarding the considerable impacts of nitrogen enrichment and mowing on the drought response of temperate grasslands, highlighting the importance of grassland management in the face of increasing anthropogenic disturbance and extreme climate events.
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