02282nas a2200181 4500008004100000245010700041210006900148300001600217490000700233520169500240100001401935700001401949700001301963700001701976700001901993700001902012856006902031 2018 eng d00aDefoliation and arbuscular mycorrhizal fungi shape plant communities in overgrazed semiarid grasslands0 aDefoliation and arbuscular mycorrhizal fungi shape plant communi a1847 - 18560 v993 a

Overgrazing substantially contributes to global grassland degradation by decreasing plant community productivity and diversity through trampling, defoliation, and removal of nutrients. Arbuscular mycorrhizal (AM) fungi also play a critical role in plant community diversity, composition, and primary productivity, maintaining ecosystem functions. However, interactions between grazing disturbances, such as trampling and defoliation, and AM fungi in grassland communities are not well known. We examined influences of trampling, defoliation, and AM fungi on semiarid grassland plant community composition for 3 yr, by comparing all combinations of these factors. Benomyl fungicide was applied to reduce AM fungal abundance. Overgrazing typically resulted in reduced dominance of Stipa Krylovii, contributing to degradation of typical steppe grasslands. Our results indicated trampling generally had little effect on plant community composition, unless combined with defoliation or AM fungal suppression. Defoliation was the main component of grazing that promoted dominance of Potentilla acaulis over Stipa krylovii and Artemisia frigida, presumably by alleviating light limitation. In non‐defoliated plots, AM fungi promoted A. frigida, with a concomitant reduction in S. krylovii growth compared to corresponding AM suppressed plots. Our results indicate AM fungi and defoliation jointly suppress S. krylovii biomass; however, prolonged defoliation weakens mycorrhizal influence on plant community composition. These findings give new insight into dominant plant species shifts in degraded semiarid grasslands.

1 aYang, Xin1 aShen, Yue1 aLiu, Nan1 aWilson, G.T.1 aCobb, Adam, B.1 aZhang, Yingjun uhttps://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.2401