Grazing management strategies on alpine meadows vary with different
degrees of degradation on northeastern Qinghai-Tibetan Plateau
Abstract
In recent decades, alpine grassland has been serimously degraded across
the Qinghai Tibetan Plateau (QTP), although grazing exclusion has been
widely adopted to restore degraded QTP grassland. It remains unknown
whether this management approach is effective for all degraded alpine
grasslands. In this study, plots with three grazing management
treatments (free grazing, FG; reduced grazing, RG; grazing exclusion,
GE) and four degradation stages (non-degradation, ND; light degradation,
LD; moderate degradation, MD; heavy degradation, HD) were compared. Our
results showed that the total aboveground biomass (AGB) and species
richness (SR) were reduced while total belowground biomass (BGB)
increased with increasing degradation, and the responses of SR, AGB and
BGB to grazing management varied with the degree of degradation. The
total AGB in the LD, MD and HD stages reduced significantly after 6
years under RG and GE, but there was no significant change of AGB in the
ND stage. Meanwhile, SR reduced significantly after 6 years under RG and
GE across all degradation stages except for HD. Furthermore, the
responses of plant functional groups to grazing management varied. After
6 years under RG and GE, the Gramineae AGB increased significantly
across all degradation levels; that of the sedges decreased (except in
the MD stage); and that of the forbs increased significantly in LD and
HD but decreased significantly in ND. Our result suggested that the
light degradation grassland can be restored by reducing grazing, and
moderate degradation and heavy degradation grassland can restored by
grazing exclusion.