草甸和沼泽植物群落功能多样性与生产力的关系

Relationship between functional diversity and productivity in meadow and marsh plant communities

功能多样性-生产力关系研究结果支持质量比假说和多样性假说,但对于这两种假说的适用条件尚有争议。通过对吉林省西部草甸和沼泽植物群落的地上生物量、2个物种多样性指标(物种丰富度和Shannon-Weaver指数)、7种植物性状的两类功能多样性指标(群落权重均值和Rao二次熵),以及土壤环境因子进行调查测量,研究了群落功能多样性与生产力的关系。结果表明:1)功能多样性与生产力的关系比物种多样性与生产力的关系更为密切;2)功能群落权重均值解释生产力变异的能力好于Rao二次熵,即优势物种对群落生产力的影响作用更大;3)水淹条件影响着功能多样性与生产力的关系,以群落权重均值为基础的质量比假说适于解释草甸群落功能多样性与生产力的关系,而以Rao二次熵为基础的多样性假说适于解释有强烈环境筛(水淹)的沼泽群落功能多样性与生产力的关系。

Aims There are two hypotheses on the mechanism of functional diversity driving ecosystem processes：one is the mass ratio hypothesis based on dominant species, and the other is the diversity hypothesis based on ecological niche. Both hypotheses have been supported by different studies, but their applicability and universality are still controversial. Our objective was to clarify whether the explanatory ability of these two hypotheses to productivity is influenced by the existence of intensive environmental filtering, which was flooding in this study. Methods Three meadow communities and three marsh communities were studied over two years in the Momoge National Nature Reserve in western Jilin Province. The aboveground biomass, species diversity （species richness and Shannon-Weaver index）, functional diversity （community weighted mean and Rao’s quadratic entropy）, and several environmental factors were compared among different communities. The functional diversity was calcu-lated for seven plant traits. The relationship between diversity index and aboveground biomass was explored by simple linear regression analysis and multiple linear regression analysis with stepwise method. Important findings Both Rao’s quadratic entropy and community weighted mean could explain more variation in community productivity than species diversity. Furthermore, both mass ratio hypothesis and diversity hypothe-sis supported the diversity-productivity relationship. However, the mass ratio hypothesis may play a relatively greater role than the diversity hypothesis, indicating that the ecosystem function mainly depended on the func-tional traits of dominant species. Intensive environment filtering in terms of flooding affected the diver-sity-productivity relationship. The mass ratio hypothesis based on community weighted mean explained more variation of the productivity in meadow communities without flooding filtering, while diversity hypothesis based on Rao’s quadratic entropy explained more variation of the productivity in marsh communities with flooding fil-tering.