PubMed · 2026-07-08
A field experiment on the Qinghai-Xizang Plateau found that fertilizing grasslands with nitrogen destabilizes plant communities over time, mainly by reducing the richness of native fodder plants and lowering soil pH. Moderate grazing, by contrast, tended to support stability by preserving a diverse mix of functional native grasses, and the study identified a tipping-point ratio where native-to-traditional herbage balance either helps or stops helping community resilience.
Nitrogen addition reduced plant species richness and native herbage richness, producing a net negative effect on aboveground biomass stability despite increasing species asynchrony.
Grazing tended to improve community biomass stability by increasing native herbage richness and compositional stability, though the effect carried substantial uncertainty.
An ecological threshold of 0.86 for the native-to-traditional herbage biomass ratio was identified: below this value, stability declined as the ratio rose; above it, further increases in native herbage proportion yielded no additional stability benefit.