呼伦贝尔草原植物功能群对围封及放牧的响应特征

Response characteristics of plant functional groups to enclosure and grazing in Hulunbuir grassland

植物功能群可以表征草地群落结构的复杂性和稳定性。文中以呼伦贝尔草原为研究对象,采用样线法开展植物群落样方调查,对比分析不同放牧强度下(轻度放牧-LG、重度放牧-HG、长期围封不放牧-EN)草地植物功能群(多年生根茎禾草-PRG、多年生丛生禾草-PBG、多年生杂草-FO、灌木及半灌木-SHS、一、二年生草本-AB、莎草-SE)的群落结构、多样性及生物量变化,以揭示围封与放牧对呼伦贝尔草原植物功能群的影响。结果表明:1)与放牧样地相比,围封后多年生杂草重要值降低,一、二年生草本功能群消失。2)轻度放牧能够维持较高的多样性水平,LG样地植物功能群的Shannon-Wiener指数、Simpson指数显著高于HG、EN样地(P<0.05)。3)围封有利于提高功能群的地上生物量,FO与PBG、PRG之间存在显著的生态互补效应。综合分析,适度放牧是较为合理的草地利用方式。

Plant functional groups(PFGs) can characterize the complexity and stability of grassland community structure. In this study, the effects of enclosure and grazing on the plant functional groups in Hulunbuir grassland was revealed by comparing with the changes of PFGs community structure, diversity and biomass among different grazing intensities(the long-term enclosure without grazing disturbance, light grazing, heavy grazing)by sampling method. The PFGs includes perennial rhizome grasses(PRG), perennial bunch grasses(PBG), forbs(FO), shrubs and subshrub(SHS), annuals and biennials(AB) and sedges(SE). The results showed that: 1) Compared with grazing, the important value of forbs under enclosure decreased, and the annuals and biennials disappeared. 2) Light grazing could maintain a high level of diversity, and the Shannon-Wiener index and Simpson index of PFGs in the LG plots were significantly higher than that in the HG and EN plots(P<0.05). 3) Enclosure was beneficial to the increase of aboveground biomass of PFGs. And there was an obvious ecological complementary effect between FO and PBG, PRG. In summary, moderate grazing is a reasonable way of grassland utilization.