放牧强度对克氏针茅草原植物功能群的影响

植物功能群及其多样性是维持群落结构复杂性和稳定性的基础,一定程度上反映着草地生态系统的健康状况。本研究以内蒙古呼伦贝尔草原的克鲁伦河流域草原为研究对象,以植物生活型划分功能群类型,比较了3种放牧强度对植物功能群的组成结构、地上生物量和优势度的影响。结果表明,1)轻牧、中牧和重牧3种放牧条件下的总物种数分别为20、23和18种,符合"中度干扰假说";3种放牧强度下多年生非禾草物种数在群落中均占较高比例。2)轻度放牧条件下物种丰富度较低,但各放牧强度下功能群多样性无显著差异(P0.05),物种丰富度与功能群多样性无显著关系。3)随着放牧强度的增加,多年生禾草和灌木、半灌木在群落中的优势地位呈现下降趋势,与之相反,多年生非禾草优势地位越来越显著。重度放牧增加了一、二年生草本在群落中的物种数和地上生物量,但与轻牧、中牧相比,其优势度无显著变化(P0.05)。

Effects of grazing intensity on plant functional groups of Stipa krylovii steppe

Plant functional groups and their diversity are the basis for maintaining the complexity and stability of community structure and to a certain extent,reflect the health of grassland ecosystems.In the present study,the grassland of the Kelunen River Basin in Hulunbeier,eastern Inner Mongolia Plateau was analyzed.Plant functional groups were compared to determine the effects of three grazing intensities on their composition of plant functional groups,aboveground biomass,and species richness.The results showed that:1) The total number of species under the three grazing conditions was 20,23,and 18,respectively,whichagreed with the “moderate disturbance hypothesis”.The number of perennial graminoids in the three grazing intensities accounted for a higher proportion in the community;2) Species richness was lower under light grazing conditions.However,there was no significant difference in the diversity of functional groups under different grazing intensities (P＞0.05).There was no significant relationship between species richness and functional group diversity;and 3) With an increase in grazing intensity,the dominance of perennial graminoids,and shrub,subshrub in the community showed a decreasing trend.On the contrary,perennial forbs were in the dominant position.Heavy grazing increased the number of species and aboveground biomass of annual or biennial herbs in the community;however,there was no significant change in the dominance compared to light grazing and moderate grazing (P＞0.05).