Resource availability differentially drives community assemblages of plants and their root-associated arbuscular mycorrhizal fungi

Understanding the role of resource availability in structuring biotic communities is of importance in community ecology. This study investigates how light and soil nutrient availability drive assemblages of both plants and their root-associated arbuscular mycorrhizal fungi (AMF). We conducted a 4-year light [full light or shade] and soil fertility [unfertilized or fertilized with (NH4)(2)HPO4] interactive manipulations in an alpine meadow ecosystem. Species and phylogenetic compositions of plant and AMF communities were simultaneously measured, and the primary ecological processes structuring both communities were inferred from the community phylogenetic analysis. Reducing light and/or increasing soil fertility significantly reduced species richness and changed community compositions of both plant and AMF. Plant community phylogenetic structure shifted from random in untreated control to overdispersion in other treatments, whereas AMF communities were phylogenetically clustered and random in unfertilized and fertilized plots, respectively. These results suggest that plant communities in treated plots were mainly determined by competitive exclusion, and that AMF communities in unfertilized and fertilized plots were determined by environmental filtering and random process, respectively. We observed strong effects of light and soil nutrient availability on both plant and AMF communities, and our findings highlight that the primary ecological processes that drive plant and AMF assemblages should be highly dependent on the level of resource availability.