关键词: 高原鼠兔, 杂草斑, 秃斑, 损失生物量, 植物群落

Abstract: We studied the variation of plant community characteristics and aboveground biomass in weeds patches and bare patches using sampling in Kobresia humilis meadow in Guoluo autonomous prefecture in habitat with different plateau pika (Ochothona curzoniae)densities in August,2010 and 2011. The results showed that there were no significant differences in total plant coverage,mean height and total aboveground biomass in weeds patches and bare patches in habitats with the same pika densities,between years,but there were significant differences among habitat different pika densities within the same year. Total plant coverage,mean height and total aboveground biomass in low density (LD),middle density (MD) and high density (HD)were significantly lower than those in Control at the 0. 05 level,but there was no obvious regularity among different densities habitat. Plant coverage,mean height and aboveground biomass of sedges,grasses and legumes in weeds patches and bare patches in LD,MD and HD were significantly lower than those in Control at the 0. 05 level,but the legumes disappeared in bare patches. Mean plant height of forbs in weeds patches and bare patches in LD and Control were significantly higher than those in MD and HD at the 0. 05 level;plant coverage and aboveground biomass of forbs were minimum in Control,they increased as the plateau pika density increased. In 2010 and 2011,the proportions of area of weeds patches were 4. 0% ,4.3% ,13.3% and 3. 8% ,4. 3% ,11. 0% in LD,MD and HD,respectively. The proportions of area
of bare patches were respectively 0.2% ,2. 6% ,4.0% and 0.2% ,2.2% ,3.4% ,loss of aboveground biomass were respectively 110. 84 kg/ hm² ,203.18 kg /hm² ,431. 58 kg / hm² and 107.67 kg /hm² ,189.46 kg /hm² ,365. 72 kg / hm² in LD,MD and HD. The relationship of plateau pika density (x) and loss of plant aboveground biomass (y)was a Lncurve.We can conclude that total plant coverage,mean height and total aboveground biomass decreased because of the activities of plateau pika,the plant functional group composition was also changed. The area of weeds patches and bare patches, and the loss of plant aboveground biomass,increased as the plateau pika density increases.

Key words: Bare patch, Loss of biomass, Plant community, Plateau pika (Ochotona curzoniae), Weeds patch