Plant litter influences the temporal stability of plant community biomass in an alpine meadow by altering the stability and asynchrony of plant functional groups

The stability of a plant community is defined as its ability to resist and be resilient to changes. Plant community stability can be driven by a range of external perturbations as well as by plant community traits. Plant litter traits (species or mass) are widely recognized drivers for plant community composition and diversity changes in grasslands. Yet, the effects of litter traits on the temporal stability of plant communities in natural grasslands are largely unknown. In this study, a field experiment was conducted at an alpine meadow on the Qinghai Tibetan Plateau to quantify the effects of litter from Elymus nutans, Kobresia setchwanensis and Ligularia virgaurea on the temporal stability of plant community biomass at five different mass levels (0, 100, 200, 400 and 600 g/m(2)). The experiment was conducted over the period from the pre-growth to peak-growth stage between 2017 and 2019, during which temporal stability of plant community biomass was assessed in relation to plant community characteristics. The effects of litter on temporal stability of plant community biomass were mainly driven by the litter mass rather than the litter species. A hump-shaped relationship between litter mass and temporal stability of plant community biomass was found, with the highest stability under intermediate litter mass treatment (200 g/m(2)). A structural equation model identified that this response was driven by the indirect effects of litter mass on the temporal stability of the biomass of the dominant (forbs) and subdominant (grasses) functional groups in the community and the asynchrony of plant functional groups. The results of this study demonstrate that plant litter traits are important drivers for maintaining plant community stability in natural grasslands, highlighting the importance of grassland management decisions (e.g. grazing intensity) relating to the quantity and quality of litter accumulation. A free Plain Language Summary can be found within the Supporting Information of this article.