草原毛虫对小嵩草草地植被群落的影响

Effects of grassland caterpillar on the vegetation community of Kobresia pygmaea alpine meadow

采用人工控制方法(移除和未移除),研究了草原毛虫对高寒草甸小嵩草草地植被群落(地上生物量、植被盖度、群落高度及植物多样性等)的影响。结果表明:在不同调查期草原毛虫种群数量随着时间的变化呈现出先增加后降低的趋势,最大值出现在7月10日,最小值是8月11日。草原毛虫对草地地上总生物量影响不大,但对莎草科和杂类草植物地上生物量影响显著。草原毛虫显著降低莎草科生物量,增加杂类草生物量(P<0.05),草原毛虫移除试验区莎草科的地上生物量比对照增加26.92%,而杂类草的地上生物量仅为对照的64.08%。草原毛虫对群落盖度影响不大,能够显著降低群落高度(P<0.05),移除试验区的高度是对照区的1.43倍。草原毛虫对丰富度指数没有影响(P>0.05),显著降低了Simpson指数、Shannon-Wiener指数和Pielou指数(P>0.05)。草原毛虫对草地群落的影响主要是由其选择性采食,改变了群落植物种的竞争关系,使其生态位发生变化。

The effects of grassland caterpillar on the vegetation community（aboveground biomass,cover,height and plant biodiversity）of Kobresia pygmaea alpine meadow were studied through caterpillar removing and non-removing.The results showed that the density of grassland caterpillar increased during the first period of the experiment and decreased after then.Grassland caterpillar had little effect on the total above-ground biomass,but reduced sedge biomass and increased forbs biomass significantly（P〈0.05）.Grassland caterpillar had no effect on coverage,but significantly reduced height（P〈0.05）.Except the richness index,grassland caterpillar significantly reduced the Simpson index,Shannon-Wiener index and Pielou index（P〈0.05）.These effects of grassland caterpillar on vegetation might be caused mainly by the caterpillar grazing behavior which changed the competitive relationship and niche among plant species.