功能多样性和功能冗余对高寒草甸群落稳定性的影响

功能多样性和功能冗余是影响群落稳定性的重要因素,但它们对稳定性影响的相对强弱尚有争论。通过在青藏高原高寒矮嵩草(Kobresia humilis)草甸为期6a的刈割(不刈割、留茬3cm、留茬1cm)和施肥(施肥、不施肥)控制实验对此进行了探讨。研究结果显示,群落稳定性随着功能多样性和功能冗余的增大而单调增加,但由于功能多样性的变异性大于功能冗余的变异性,功能多样性与物种多样性间的相关性强于功能冗余与物种多样性间的相关性,功能多样性与群落稳定性间的相关性也强于功能冗余与群落稳定性间的相关性,因此,尽管功能冗余产生的保险效应对维持群落稳定性具有促进作用,但功能多样性的互补效应对维持群落稳定性的作用更大。结果表明,功能多样性和功能冗余对群落稳定性的相对影响与其变化程度正相关,功能多样性与群落稳定性的变化具有更紧密的联系,能更好地预测生态系统稳定性的变化。研究为草原生态系统的可持续管理提供了重要启示。

Effects offunctional diversity and functional redundancy on the community stability of an alpine meadow

Functional diversity and functional redundancy are crucial to maintaining the stability of a community, but the strength and relative importance of these effects remains poorly understood. In this study, a field manipulation experiment was conducted in an alpine Kobresia humilis meadow at the Haibei Research Station of the Chinese Academy of Sciences from 2007 to 2012, with the aim of gaining insight into the relationship between community stability, functional diversity, and functional redundancy. The experiment used a split-plot design with three clipping levels (stubbled 1 cm, 3 cm, and unclipped) used on the whole plot, and subplots were treated with or without fertilizer (12.75 g m^-2 a^-1 urea + 3.06 g m^-2 a^-1 ammonium phosphate or unfertilized). Our results showed that the community stability monotonously increased with increasing functional diversity and functional redundancy; however, the effect of functional diversity on stability was greater than that of functional redundancy, given that the coefficient of variation of functional diversity under different treatment combinations was greater than that of functional redundancy. Furthermore, the degree of positive correlation between functional diversity and species diversity was stronger than that between functional redundancy and species diversity. We also found a closer positive relationship between functional diversity and community stability than that between functional redundancy and community stability. Although the insurance effect from functional redundancy may improve the stability of a community, the complementary effect of functional diversity on stability appears to be much greater. As such, this result suggests that the relative strength of the effects of functional diversity and functional redundancy on community stability is positively correlated with the degree of variation in functional diversity and redundancy, which confirmed our speculations. Meanwhile, functional diversity is more tightly related to the community stability and can be a better predictor of ecosystem stability than species diversity or functional redundancy. Our study provides a critical insight into sustainable management of rangeland ecosystems.