生物多样性 ›› 2002, Vol. 10 ›› Issue (2): 135-142.doi: 10.17520/biods.2002016

所属专题: 生物多样性与生态系统功能

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生产力、可靠度与物种多样性:微宇宙实验研究

张全国, 张大勇*   

  1. 生物多样性与生态工程教育部重点实验室,北京师范大学生态学研究所,北京 100875
  • 收稿日期:2001-11-26 修回日期:2002-04-09 出版日期:2002-05-20

Productivity, reliability and species diversity in aquatic microcosms

ZHANG Quan-Guo, ZHANG Da-Yong*   

  1. Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering & Institute of Ecology,Beijing Normal University,Beijing 100875
  • Received:2001-11-26 Revised:2002-04-09 Online:2002-05-20

近年来,生物多样性与生态系统功能的关系成为生态学领域内一个重大科学问题。有一些实验研究表明,物种多样性的降低会使生态系统的生产力、稳定性等功能受损。然而对这些实验结果的解释却产生了激烈的争论,因为有两种机制——“生态位互补”和“抽样效应”都可能会产生这种结果。本项研究通过微宇宙实验探讨了物种多样性与生态系统生产力及其可靠度的关系。在10种单细胞藻类中随机抽取物种,构建具有不同物种丰富度的水生群落,并使同一物种丰富度水平的群落之间没有物种交叉,然后检测物种丰富度对群落生产力及其可靠度的作用。群落生产力以藻类干重表示,自实验开始后第4周起,每周测定1次,共测5次。结果显示:物种丰富度对群落生产力有正效应,并且这种正效应随时间推移而增强;许多混合群落的生产力超过了该群落内所有物种的单产,即发生了超产现象;在实验初期某些特定物种对一些混合群落生产力有主要贡献,而在实验后期却没有任何多物种群落的生产力受个别物种存在与否的影响;群落生产力的可靠度与物种丰富度之间不存在显著相关。从以上结果可以得知:物种多样性对群落生产力有逐渐增强的正效应;物种多样性对生产力的正效应是生态位互补和抽样效应共同作用的结果,但随时间推移,抽样效应逐渐减弱。本项研究支持了关于生态位互补与抽样效应在多样性正效应中共同起作用的认识,并说明了这两种机制的相对重要性随时间推移而发生改变。

The relationship between biodiversity and ecosystem functioning has emerged as a major issue in ecology. Several experiments have provided evidence for the notion that decreasing species diversity may impair ecosystem processes. The interpretation of these experiments, however, has been controversial because two types of mechanisms, “niche complementarity” and “sampling effect”, may operate. By means of microcosm experiments, we investigated the relationship between species diversity and ecosystem functioning. Aquatic microcosms in laboratory conditions are designed to contain different numbers of unicellular algal species, with no overlap in species composition between microcosms with the same number of species. Algal dry mass, an index of community productivity, was measured once a week after four weeks from the start of the experiment. The experiment lasted for a period of eight weeks, and in total, five measurements were obtained. Algal species richness had progressively stronger effects on community productivity. A number of higher-diversity mixtures outperformed the most productive monoculture as the experiment proceeded. Certain species dominated some mixtures in initial stages, but this effect disappeared in later stages. There was no significant correlation between reliability of community productivity and species richness. The experimental results reported here support the recent suggestion that both niche complementarity and sampling effect may be involved in the diversity effect, and show that the relative importance of the two mechanisms may undergo substantial changes through the course of community maturation.

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