Species diversity of arbuscular mycorrhizal but not ectomycorrhizal plants decreases with habitat loss due to environmental filtering

Aims Understanding the distribution pattern of biodiversity in fragmented landscapes is important for conserving biodiversity. The mutualistic interaction between mycorrhizal fungi and plants is an important trait influencing ecological processes, such as plant response to environmental conditions; however, we lack a general understanding of how habitat fragmentation differently affects plant diversity of different mycorrhizal types. Methods The diversity of arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) plants, including the number of species on islands, the number of species per plot, and the number of individuals per plot, were calculated on 11 islands within a hydroelectric reservoir in China. We tested the influence of island attributes (island area and isolation), abiotic and biotic variables on the diversity of AM and EcM plants. Results There was a significant positive correlation between island area and species diversity of AM plants, but not EcM plants. After controlling for island attributes, abiotic variables and the diversity of AM fungi significantly affected the diversity of AM plants per plot. The abiotic and biotic variables explained more variance in the number of AM plant species (58%) and number of individuals of AM plants per plot (52%) than EcM plants (less than 20%). The diversity of AM plants but not EcM plants was higher in interior than in edge plots of the islands. Conclusion The results indicate that the decrease of plant species diversity with habitat loss was probably related to the extinction of AM plants caused by selection of abiotic variables and diversity of AM fungi.