Response of species diversity and stability of typical steppe plant communities on the Mongolian Plateau to different grazing patterns

Grasslands represent a major biome on Earth and play a vital role in
ecosystem functioning and dynamics. However, owing to the variations among
grassland types, the impact of grazing on plant community diversity and
stability remains unclear. This study is based on the typical steppe of
the Mongolian Plateau. Field sampling and data analysis were combined to
qualitatively and quantitatively investigate the structural
characteristics, species diversity, and stability of plant communities
under varying grazing intensities, i.e., four-season nomadic, two-season
rotational, and sedentary grazing (FSNG, TSRG, and SG, respectively). The
results indicated that FSNG pastures exhibited the largest number of plant
species while FSNG and TSRG pastures exhibited relatively high importance
values for the primary dominant species. Carex duriuscula, Chenopodium
glaucum, and Cleistogenes squarrosa were
prominent in SG pastures, with C. duriuscula having the largest
importance value. The mean height, cover, and aboveground biomass of plant
communities in FSNG were significantly higher than those in SG (P <
0.05), with no significant difference observed between FSNG and TSRG. FSNG
also demonstrated the highest Shannon–Wiener, Simpson, and Pielou indexes.
The Shannon–Wiener and Simpson indexes between the FSNG, TSRG, and SG
pastures showed significant differences (P < 0.05). Nomadic plant
communities displayed positive loosely interspecific traits, suggesting
independence and positive succession. Conversely, communities in TSRG and
SG exhibited negative correlations and higher instability. The stability
analysis ranked community stability as FSNG > TSRG > SG,
suggesting that judicious grazing practices could enhance grassland
stability. The findings reveal that grazing patterns influence
plant community composition and function and that FSNG pastures promote
higher species diversity, perennial dominance, and overall stability
compared to TSRG and SG pastures.