Abstract:
Species richness plays an important role in ecosystem stability and health. Mycorrhizal type is an important factor affecting ecological processes. How mycorrhizal types affect understory herb species richness and their responses to environmental changes remain largely unknown. We investigated the effects of mycorrhizal types on species richness and their responses to environmental change in understory herbaceous communities based on data of three mycorrhizal types of dominated trees (including 1604 arbuscular mycorrhiza (AM) trees, 4654 ectomycorrhiza (ECM) trees, and 5568 AM+ECM trees) and environmental factors in America. The results showed significant differences in species richness of herbaceous plant communities among different mycorrhizal types. Forests with higher dominance of AM plants tended to have higher herbaceous plant richness, supporting the mycorrhizal mediation hypothesis. The impacts of environmental factors (latitude, temperature, precipitation, nitrogen deposition, and soil characteristics) on species richness of herbaceous plant communities depended on mycorrhizal type of forests. The species richness of understory herbs in AM, ECM, and AM+ECM forests was mostly affected by nitrogen deposition, temperature, and soil pH, with the relative importance of 42.3%, 41.1% and 48.7%, respectively. Mycorrhizal types of dominant trees played a vital role in regulating the species richness of understory herbs and influenced their responses to environmental changes.
物种丰富度对生态系统的稳定和健康有着重要意义,菌根类型是影响生态过程的一个重要因素,目前缺乏对菌根类型影响林下草本植物物种丰富度及其对环境变化响应的认识。本研究基于美国1604个丛枝菌根(AM)森林、4654个外生菌根(ECM)森林和5568个AM+ECM型森林的草本植物群落物种丰富度和环境因素数据,探讨菌根类型对物种丰富度及其对环境变化响应的影响。结果表明:不同菌根类型森林的草本植物群落物种丰富度间有显著差异,含有AM优势植物越多的森林的草本植物丰富度越高,这一结果为菌根介导假说提供了有力的证据。环境因子(纬度、温度、降水、氮沉降及土壤性状)对森林草本植物群落物种丰富度的影响也随菌根类型的不同而有着较大差异。在AM型、ECM型和AM+ECM型森林植被中,林下草本植物群落的物种丰富度分别受氮沉降、温度和土壤pH的影响最大,这些因素的相对重要性高达42.3%、41.1%和48.7%。森林优势植物的菌根类型在调节林下草本植物群落物种丰富度方面有着重要作用,且影响着群落物种丰富度对环境变化的响应。.