植物群落物种多样性对生态系统生产力的影响

Effects of plant species diversity on productivity of ecosystem

物种多样性对生态系统功能的影响是生态学领域所研究的核心科学问题之一。本研究利用人工构建的一年生植物群落,就植物群落物种多样性、植物功能群多样性和功能群成分对生态系统生产力的影响进行了研究,并对物种多样性-生态系统功能关系的作用机制———取样效应和生态位互补效应进行了验证。结果表明,随着物种多样性的增加,群落生产力呈增加趋势,物种多样性对生态系统功能存在正效应,物种多样性增加的总体效应可通过生产力与物种数的二次函数关系y=-37.463x2+478.63x+1097.3,(R2=0.9167)得到较好的体现。功能群多样性和功能群成分均对系统功能有显著影响。总体而言,物种数一定时,功能群多样性较高的群落其生产力水平也较高,而功能群多样性一致时,含C3、C4功能成分的群落其生产力水平较其他群落的高。分析结果还表明,在多样性-生态系统功能关系中,取样效应和生态位互补效应共同发生作用,说明物种的特性及物种在资源利用方面表现出的异质性对生态系统功能可能都有重要影响。

The effects of species diversity on ecosystem functioning is one of the most important problems in ecosystem research. To determine whether species diversity affected ecosystem functioning, we performed an experiment using annual plant communities in which the species richness, functional group richness and functional composition was manipulated. We also tested whether the richness effects was the result of two types of mechanisms operating, 'sampling effect' and 'niche complementarity'. The results indicated that higher species richness significantly enhanced community productivity, and annual plant species richness had positive effects on community productivity. The relationship between species richness and community productivity could be represented by quadratic equation y=-37.463x^2+478.63x+1 097.3 (R^2=0.916 7). Functional group richness and functional composition both had significantly effects on ecosystem functioning. In average, the community with more functional groups, while species richness maintained constant, had higher level of community productivity, and the community containing C_4 and C_3 functional group had higher productivity level than other communities in which same functional groups were included. The results also suggested that both sampling effect and niche complementarity effect may operate mechanistically in the diversity effect, and this show that the species with particular traits, such as higher productivity and competitive ability, and the species with resource partitioning are likely to have large impacts on ecosystem functioning.