Erratic precipitation and clipping frequency reshape the community structure and species stability of Leymus chinensis steppe

Leymus chinensis steppe is subject to degradation under the combined stresses of climate change and human disturbance. This study aimed to determine the independent and compound effects of precipitation and clipping frequency on the community structure and species temporal stability of L. chinensis steppe. Six treatments were applied in a 9-year field study, comprising three precipitation regimes (precipitation reduced by 50%, R1; unchanged from ambient precipitation, R2; and increased by 50%, R3) and two clipping frequencies (clipping once or twice per year, C1 and C2). We evaluated the soil hydrothermal status, dry matter, importance value and temporal stability of five important species (L. chinensis, Artemisia eriopoda, Cleistogenes squarrosa, Potentilla tanacetifolia, and Stipa krylovii) in the L. chinensis community. The results showed: Change in the soil volumetric water content (+/- 2.4%) altered the competitive capability of L. chinensis relative to its associated species. Drought was beneficial to S. krylovii, wet status was favorable to C. squarrosa and P. tanacetifolia, whereas drought and a wet regime both reduced the importance value and temporal stability of L. chinensis. Erratic precipitation, rather than clipping frequency, decreased the temporal stability of L. chinensis. Net primary productivity and dry matter of L. chinensis were strongly correlated under drought or wet regimes. Restoration of the key species L. chinensis and controlling grazing intensity in severe drought or wet conditions are recommended strategies for sustainable management of L. chinensis steppe.