线虫区系分析指示土壤食物网结构和功能研究进展

Approach of nematode fauna analysis indicate the structure and function of soil food web

土壤食物网结构复杂,功能众多,直接测定土壤食物网各功能群生物量并结合数学模型来推断土壤食物网结构和功能,工作量大且分析过程繁琐。线虫生态学的发展为土壤食物网的研究开辟了一条新的思路,即利用线虫区系分析来定性推断食物网的结构和功能。线虫作为土壤中数量最丰富的后生动物,占据着土壤食物网的中心位置,其物种多样性、食性多样性、生活史策略多样性、功能团多样性奠定了其作为土壤食物网结构和功能指示生物的生态学基础。线虫区系分析根据发展历史可以分为个体分类、生活史策略分类、功能团分类和代谢足迹分类四个时期,其中后两个时期主要用于推断土壤食物网结构和功能。基于功能团的线虫区系分析将线虫的食性和生活史策略结合起来,发展出一系列指数来判断土壤食物网的连通性、食物网链长度、外界养分投入情况、分解途径及对外界干扰的响应等。基于代谢足迹的线虫区系分析在功能团分析基础上,加入线虫能流分析,从而定性反映了土壤食物网功能的大小。两者在指示土壤食物网自下而上调节及对植物线虫控制等方面起着重要的作用。

Soil food web is a nonlinearity system with complex structure and multifunctions, and described by three step-up levels of connectedness web, energy flow web and functional web. However, it is difficult to infer directly the structure and function by measuring the biomass of soil organism and calculating the energy flux among the functional groups with modes. Therefore, it is important that searching a simple bioindicator evaluate indirectly the structure and function of soil food web. Nematode is a good biondicator of soil food structure and function because it is the most abundant metazoan with high diversity of species composition, feeding habits, life history strategies and functional guilds, and participate in several links and energy channels within the soil food web, and occupy the central position of soil food web. The paper reviewed the history, principle, calculation, meaning of nematode fauna analysis （NFA） as well as the application of NFA in managing soil food web. The NFA can be divided four developing stages of individual taxon, life history strategy taxon, functional guild taxon and metabolic footprint. Actually, only the latter two stages give insight into soil food web. The NFA based on functional guilds developed a serial indices through integrating the feeding habit and lifehistory strategy, and indicate the soil food web connectedness and condition, food chain length, decomposition path, the input of external resource and response to disturbance. However, the NFA based on functional guilds only provide the relative proportion of services and functions, but not of their magnitude. The magnitude can be indicated by the NFA based on metabolic footprint that determined by the carbon of nematode biomass and respiration. Seven metabolic footprint indices were developed and some of them, such as enrichment footprint and structure footprint, are corresponding to the enrichment index and structure index that deduced from NFA based on functional guilds. NFA based on functional guild taxon and metabolic footprint had been used widely to evaluate the bottom-up regulation of soil food web through the input of external resource and top-down suppression on plant parasite nematodes.