菌根类型对森林树木净初级生产力的影响

摘要

In terrestrial ecosystems, symbiotic associations between plant roots and mycorrhizal fungi are near ubiquitous, with 90 per cent of all plant species forming mycorrhizas. At the global scale, mycorrhizal symbioses, including seven types varied between host species and fungal taxa, play key roles in important ecosystem processes and functions. To enhance our understanding of the functional diversity of mycorrhizal associations, we analyzed the impact of mycorrhizal strategies on net primary productivity (NPP) on the global scales based on a global forest database. The results showed that the NPP of trees varied with the differences of mycorrhizal strategy at the global forest ecosystem. When the different mycorrhizal strategy was considered, the NPP of trees was higher in arbuscular mycorrhizas (AM) dominated forest with a mean of C 679.49 g-m-2a-1 than in ectomycorrhizas (ECM) dominated forest with a mean of C 479.00 g·m-2·a-1. The response of above-and below-ground NPP of trees also highly varied among different mycorrhizal strategies. AM contributed more to below-ground NPP than above-ground when compared with ECM. It was contrary of the effects of ECM. In addition, mycorrhizal strategy affected significantly the NPP of leaf, stem, branch, and coarse and fine root AM increased the NPP of leaf and fine root, and ECM enhanced the NPP of stem and branch. We conclude that the total NPP and NPP of their different parts were significantly different with the variation of mycorrhizal strategies.%菌根是土壤真菌与植物根系形成的共生体,存在于绝大多数植物(90％)的根系和生境中.菌根共有7种类型,在生态系统的过程和功能方面都扮演着十分重要的角色.为了增强对菌根在森林生态系统中重要功能的理解,文章基于全球森林数据库,在全球尺度上研究了不同菌根类型对森林树木净初级生产力(NPP)的影响.结果表明,森林树木NPP随菌根类型的不同而不同,AM类型菌根森林的NPP[679.49 g·m-2·a-1(以C计)]要显著高于含ECM类型菌根的森林[479.00 g·m-2·a-1(以C计)]；菌根类型的不同对森林树木地上和地下及其各组分NPP的影响和贡献也存在着显著的不同,AM类型菌根对地下NPP的贡献要高于ECM菌根,而ECM菌根对地上NPP的贡献则较大.菌根类型对地上、地下NPP组分的影响分析则表明,AM类型的菌根对树叶和细根NPP的贡献较大,而ECM类型菌根则对树木主干和枝NPP的贡献较大.可见,森林树木总体NPP及其各组分NPP都随着菌根类型的不同而存在显著的差异.