Vegetation composition and interspecific associations of alpine meadow under different utilization rates on the northeast Qinghai-Tibet Plateau

The vegetation community structure and interspecific association are the main evaluation indices of grassland stability and community succession. It is important to study the vegetation composition and interspecific association under different utilization rates for grassland management and revealing the mechanism of stability maintenance in alpine meadow. This study analyzed vegetation composition, inter-species relationship and community stability under the annual average grassland utilization rate of 60%～70% (moderate utilization grassland, MG), 80%～90% (heavy utilization grassland, HG) and > 90% (extreme utilization grassland, EG) in the northeastern Qinghai-Tibet Plateau. It aimed to explore the relative suitable grassland utilization rate in the northeastern Qinghai-Tibet Plateau. The results showed that 1) MG grassland dominated by grass (Elymus nutans, Stipa krylovii and Poa crymophila) and HG grassland dominated by Elymus nutans, Kobresia humilis and Stipa krylovii, while the EG grassland dominated by Kobresia humilis. 2) With the increasing of utilization rate, plant species richness decreased, and the β diversity index, Shannon-Wiener diversity index and Simpson dominance index showed a declining trend, reaching the lowest in EG grassland; the aboveground biomass proportion of sedge increased, while the aboveground biomass proportion of grass decreased. 3) Compared to EG grassland, MG and HG grasslands had a closer interspecific association and stronger community stability, and EG grassland showed a trend of degradation. The study concluded that the moderate utilization rate under the rotational grazing pattern was beneficial to maintain the vegetation community stability in alpine meadow.