Abstract. Litter decomposition and N release are the key processes that strongly
determine the nutrient cycling at the soil–plant interface; however, how
these processes are affected by grazing or grazing exclusion in the alpine
grassland ecosystems on the Qinghai-Tibetan Plateau (QTP) is poorly
understood. So far few studies have simultaneously investigated the influence
of both litter quality and incubation site on litter decomposition and N
release. Moreover, previous studies on the QTP investigating how grazing
exclusion influences plant abundance and biodiversity usually lasted for many
years, and the short-term effects have rarely been reported. This work
studied the short-term (6 months) effects of grazing and grazing exclusion on
plant community composition (i.e., plant species presented) and litter
quality and long-term (27–33 months) effects on soil chemical
characteristics and mixed litter decomposition and N release on the QTP. Our
results demonstrate that (1) shorter-term grazing exclusion had no effect on
plant community composition but increased plant palatability and total litter
biomass; (2) grazing resulted in higher N and C content in litter; and (3) grazing
accelerated litter decomposition, while grazing exclusion promoted N
release from litter and increased soil organic carbon. In addition,
incubation site had significantly more impact than litter quality on
litter decomposition and N release, while litter quality affected
decomposition in the early stages. This study provides insights into the
mechanisms behind the nutrient cycling in alpine ecosystems. We suggest that
periodic grazing and grazing exclusion is beneficial in grassland management
on the QTP.
Plant community composition and structure under short-term grazing exclusion in steppic arid rangelands
