Does the number or size of plant patches contribute to vegetation
restoration of restoring degraded alpine steppes via grazing exclusion?
Abstract
Arid and semi-arid vegetation is characterized by plant patches of
different sizes, and plant cover is determined by patch size (PS) and
number of patches (NP). However, it is still unclear how PS and NP
contribute to the restoration of degraded grasslands through grazing
exclusion (GE). Transect lines were sampled in six alpine steppe
communities in Tibet in 2017 and 2018. Both PS and NP were assessed and
compared between inside and outside grazing exclosures. Our results
showed that grazing exclosures increased the mean size but decreased the
total number of plant patches. This pattern of change was common to
other species and could not be attributed to a shift in community
composition. The results suggest that the recovery of the degraded
alpine steppe is being driven by PS at the expense of NP. By promoting
the expansion of the larger patches while excluding the smaller ones, GE
led to an aggregating pattern with a higher proportion of bare ground,
potentially reducing primary productivity.