Effect of grazing on chemical characteristics of litter in alpine grassland during the cold season

To understand the effects of grazing on litter decomposition characteristics during the cold season in the alpine grassland of Qinghai Tibet Plateau, biomass and C, N, and P chemical measurements of litter in the cold season pasture under three different grazing intensities were studied. The results showed that the amount of litter decreased with an increase in grazing intensity. In light grazing (LG, 22.50 sheep unit·ha-1), moderate grazing (MG, 26.25 sheep unit·ha-1), and heavy grazing (HG, 32.04 sheep unit·ha-1) alpine meadows, the litter biomass ranged from 45.72 to 125.52, 17.32 to 56.6, and 8.64 to 30.96 g·m-2, respectively. The C content of the existing litter under different grazing intensities gradually decreased during the grazing season, and the C content of litter decreased in the order of LG, MG, and HG during the same period. In addition, the C content of litter showed a significant increasing trend in MG and HG during the rest from grazing period. The content of N in litter decreased during the grazing period, whereas the P content of the litter decreased in the order of HG, MG, and LG. During the rest from grazing period, the decreasing order of P content in the existing litter was HG, LG, and MG. The C/N of existing litter was above 90 in LG, and the C/P of existing litter was higher during the early rest from grazing period (July), which was greater than 1 000. The results from the present study demonstrated that litter loss rate increased significantly, N content decreased, C content did not change significantly, and P content appeared enriched with an increase in grazing intensity.