图1. 陆地生态系统中植物和土壤微生物活动相互关联的概念模型。一方面植物凋落物为土壤微生物生长活动提供底物, 同时土壤微生物分解底物产生的无机氮供植物生长利用, 它们之间是互利共生的。另一方面, 当养分供应(特别是氮)缺乏时, 它们之间又转换为竞争关系。改绘自Zak等(2000)。

Fig. 1. A conceptual model illustrating the links between plant and soil microbial activity in terrestrial ecosystems. On one hand, plants and microbes are mutualistic, since plant residues constitute the main substrate for microbial biomass that in turn produces inorganic nitrogen used by plants. On the other hand, their interaction is in competition for soil nutrients, N in particular. The competitive interaction is regulated by the relative distribution of roots and microbes in the soil, but it also depends on the pathway followed by the mineralized N. Redraw based on Zak et al. (2000).