高原鼠兔对高寒草甸植物群落生物量的影响

Effects of plateau pika (Ochotona curzoniae) on plant community biomass in alpine meadow

2010年和2011年8月在青海省果洛州矮嵩草草甸,采用样方法测定了不同密度高原鼠兔栖息地内杂草斑和秃斑植物群落特征及地上生物量的变化。结果表明:2010年与2011年相比,相同高原鼠兔密度的栖息地内杂草斑和秃斑植物总盖度、平均高度和总地上生物量差异不显著,但同一年份不同密度栖息地间差异显著。高原鼠兔低、中、高密度栖息地植物总盖度、平均高度和总地上生物量显著低于无鼠兔对照组(P<0.05),不同密度间无明显变化规律。低、中、高密度栖息地的莎草、禾草和豆科植物盖度、平均高度和地上生物量显著低于无鼠兔对照组(P<0.05),秃斑上豆科植物消失;杂类草平均高度在低密度栖息地和无鼠兔对照组显著高于中、高密度栖息地(P<0.05),盖度和地上生物量对照组最小,随高原鼠兔密度增加呈增加趋势。2010年和2011年,高原鼠兔低、中、高密度栖息地内杂草斑面积分别占样地面积的4.0%、4.3%、13.3%和3.8%、4.3%、11.0%,秃斑面积分别占样地面积的0.2%、2.6%、4.0%和0.2%、2.2%、3.4%;植物损失地上生物量分别为110.84 kg/hm2、203.18 kg/hm2、431.58 kg/hm2和107.67 kg/hm2、189.46 kg/hm2、365.72 kg/hm2。高原鼠兔的密度(x)与植物损失地上生物量(y)之间存在对数曲线关系,说明高原鼠兔的活动显著降低了植物总盖度、平均高度和总地上生物量,同时也改变了植物功能群组成。随高原鼠兔密度增加,栖息地内杂草斑、秃斑的面积和植物损失地上生物量呈增加趋势。

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 thelegumes 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 min- imum 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 ar- ea 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/hmz, 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 platean pika density （x） and loss of plant aboveground biomass （y） was a Ln- curve. We can conclude that total plant coverage, mean height and total aboveground biomass decreased because of the ac- tivities of plateau pika, the plant functional group composition was also changed. The area of weeds patches and bare pat- ches, and the loss of plant aboveground biomass, increased as the plateau pika density increases.