消费者多样性对食物网结构和生态系统功能的影响

Effects of consumer diversity on food web structure and ecosystem functioning:current knowledge and perspectives

前所未有的生物多样性丧失使人们越来越关注生物多样性的生态系统功能。现有的绝大多数研究都是局限在单一营养级别上,主要是植物上,但是今天越来越多的证明表明消费者的多样性对生态系统结构和功能具有深刻影响。综述了消费者多样性对相邻或非相邻营养级的种群密度、物种多样性和生产力等方面影响的最新进展,同时也提出了若干研究展望。总体上,消费者多样性,无论是草食动物还是肉食动物,都倾向于增加该消费者所在营养级的养分和能量利用效率,以及生产力。这可能源于取样效应,或者物种之间的互补作用,类似于植物物种多样性影响初级生产力的机制。草食动物可能降低或者提高植物物种多样性,或者没有显著影响,其具体效应取决于生态系统生产力水平和草食动物的大小。捕食者能通过直接抑制草食动物而间接提高植物的多样性和生产力,但这种效应的大小差异很大,甚至效应的方向,都可能随团体内捕食者所占的比例而改变。未来的研究,应该考虑应用较大尺度的实验来检测食物网复杂营养关系对生态系统特性的影响,继续探讨消费者对生态系统功能的影响机制。认为异速生长法则和生态化学计量学在食物网组分关系研究中的应用将有利于增强人们对消费者-生态系统功能关系的理解。另外,全球变暖和转基因植物对食物网中消费者结构和生态系统的功能的影响也将是未来的一个重要研究方向。

The role that biodiversity plays in ecosystem functioning has attracted much attention during the last decade because of concern over the currently unprecedented rate of biodiversity loss. However, most studies of diversity —— ecosystem functioning relationships have been performed in single trophic level, mostly plant communities, although recent studies have shown that consumers diversity have a profound effect on the structure and functioning of ecosystems. This paper reviews recent developments on the effect of consumer diversity on population density, species diversity, and production, of adjacent and non-adjacent trophic levels, and also suggests several research perspectives. In general, consumer diversity, of either herbivore or predator, tends to increase nutrient and energy use efficiency, and the productivity of the trophic level, which may result from sampling effect, and/or complementary between species, as found for the relationship between plant species diversity and primary productivity. Herbivores may decrease or increase plant species diversity, biomass, and primary production, depending on ecosystem productivity, herbivore identities, and environmental gradient. Predators usually have an indirect, positive effect on the plant diversity and primary production via a direct, negative effect on the herbivores, but the positive effect can be weakened and even the effect direction can be changed when intraguild predators occupy a large proportion of the predator density. In future, large-scale experiments, both of spatial and temporal,should be conducted to explore the effect of complex trophic interaction in real food webs on ecosystem properties, especially of terrestrial ecosystems. We propose that allometric growth law and ecological stoichiometry theory may be applied to study the trophic cascading effect of consumer diversity in order to improve the understanding of the relationship between biodiversity and ecosystem functioning. In addition, the effects of global warming and growing transgenic plants on consumer diversity and ecosystem functioning should be studied in recent future.