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 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.