Abstract:
Vegetation is a crucial component of any ecosystem and to preserve the
health and stability of grassland ecosystems, species diversity is important. The
primary form of grassland use globally is livestock grazing, hence many studies
focus on how plant diversity is affected by the grazing intensity, differential
use of grazing time and livestock species. Nevertheless, the impact of the
grazing time on plant diversity remains largely unexplored. We performed
a field survey on the winter pastures in alpine meadows of the Qinghai-
Tibetan Plateau (QTP) to examine the effects of grazing time on the vegetation
traits. Livestock species, grazing stocking rates and the initiation time of the
grazing were similar, but termination times of the grazing differed. The grazing
termination time has a significant effect on most of the vegetation traits in
the winter pastures. The vegetation height, above-ground biomass, and the
Graminoids biomass was negatively related to the grazing termination time in
the winter pastures. In contrast, vegetation cover and plant diversity initially
increased and subsequently decreased again as the grazing termination time
was extended. An extension of the grazing time did not have any effect
on the biomass of forbs. Our study is the first to investigate the effects
of grazing during the regrowth period on vegetation traits and imply that
the plant diversity is mediated by the grazing termination time during the
regrowth period in winter pastures. These findings could be used to improve
the guidelines for livestock grazing management and policies of summer and
winter pasture grazing of family pastures on the QTP from the perspective of
plant diversity protection.
