内蒙古高原针茅草原植物多样性与植物功能群组成对群落初级生产力稳定性的影响

内蒙古高原4类地带性草原群落，贝加尔针茅（Stipa baicalensis Roshew.）群落、大针茅（S.grandis P.Smirn.）群落、克氏针茅（S.krylovii Roshev.）群落和小针茅（S.klemenzii Roshev.）群落初级生产力连续12年的定位研究结果表明，在气修波动下群落生产力及其稳定性与群落多样性特征的变化是一致的，从贝加尔针茅群落到小针茅群落。植物多样性显下降，群东中起重要作用的植物功能群的数量逐渐减少，群落初级生产力及其稳定性也逐渐降低。生活型功能群组成中，多年生丛生禾草、多年生根茎禾草与苔草和多年生杂类草功能群多样性与群落初级生产力稳定性极显地呈正相关。生态类群组成中，旱生植物和中旱生植物功能群多样性也与群落初级生产力稳定性极显地呈正相关，生态位互补效应（niche complementary effect）可能是高植物多样性群落具有高生产力的机制，而植物多样性对群落初级生产力稳定性的影响可能是通过不同功能群间的补偿作用来实现的。

The Influence of Plant Diversity and Functional Composition on Ecosystem Stability of Four Stipa Communities in the Inner Mongolia Plateau

The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa communities in the Inner Mongolia Plateau. The research work was based on a 12_year study (from 1984 to 1995) of species abundance, diversity, and primary productivity of four Stipa communities, i.e. S. baicalensis Roshev., S. grandis P. Smirn., S. krylovii Roshev., and S. klemenzii Roshev. respectively. The Shnnon_Wiener index was used as a measurement of plant diversity, while functional composition was used to differentiate the functional groups that were included in the communities. The plant species of four Stipa communities were classified into functional groups based on the differences in life forms and ecological groups, which influence their performance in resource requirements, seasonality of growth, tolerance to water stress, and life history. Plant species were classified into five functional groups based on their differences in life form, shrubs and half shrubs, perennial bunch grasses, perennial rhizome grasses, forbs, annuals and biennials. Based on their differences in water requirement these species were classified into four functional groups: xerads, intermediate xerads, intermediate mesophytes, and mesophytes. The results showed: 1) Plant species diversity stabilized ecosystem processes. Shannon_Wiener index were 2.401?4, 2.172?0, 1.624?8, 0.354?3 from S. baicalensis community to S. grandis, S. krylovii and S. klemenzii community, respectively. The dynamics of the aboveground net primary productivity (ANPP) for a 12_year's period showed a reverse pattern, the coefficients of variation of the four communities were 21.94%, 20.63%, 29.21% and 39.72% respectively. 2) The life form functional group component of diversity was a greater determinant of the ecosystem processes than the species component of diversity. The effects of perennial bunch grasses, perennial rhizome grasses and forbs on community stability were highly significant. 3) The ecological group component of diversity was also a great determinant of the ecosystem processes. The effects of xerads, intermediate xerads, and mesophytes on community stability were also very strong.