Environmental filtering (niche process) and dispersal limitation (neutral process) are two primary forces driving community assembly in ecosystems. As an important component of soil microorganism communities, ectomycorrhizal (EM) fungi establish mutualistic relationships with plants and play key roles in biogeochemical cycling and plant community dynamics. Fagaceae plants, as EM hosts with high species diversity in China, have very important ecological and economic values. However, how environmental filtering and dispersal limitation processes affect the Fagaceae-associated EM fungal community at regional scales is poorly documented. In this study, we collected 760 root samples of 61 plant species belonging to Castanea (3 species), Castanopsis (20 species), Cyclobalanopsis (12 species), Fagus (3 species), Lithocarpus (7 species) and Quercus (16 species) at 30 Chinese forest sites (geographic distance up to ~3,757 km). The EM fungal communities were examined by using Illumina Miseq sequencing of ITS2 sequences. The relative effect of environmental filtering (i.e. host plant phylogeny, soil and climate) and dispersal limitation (i.e. spatial distance) on the EM fungal community was disentangled using various models.
Results/Conclusions
In total, 2,706 operational taxonomic units (OTUs) of EM fungi were recovered at a 97% sequence similarity level, corresponding to 54 fungal lineages. The EM fungal OTU richness ranged from 21.3 ± 0.8 to 27.8 ± 1.1 (mean ± SD) in the six plant genera, and was significantly affected by soil pH and nutrients and host phylogeny. The nonmetric multidimensional scaling analysis showed that the EM fungal community composition was significantly different among the six plant genera, except between Lithocarpus and Cyclobalanopsis. The EM fungal community composition was mainly affected by host phylogeny (14.0% of variation explained), followed by spatial distance (5.3%), climate (0.8%), soil factors (each ≤ 0.3%) and altitude (0.3%). EM fungus/host preference analysis showed that 55.7% of host plant species and 67.9% of abundant EM fungal OTUs (> 2,000 reads) showed significant preferences toward specific symbiotic partners. The study suggests that the EM fungal community assembly is forced by both environmental filtering and dispersal limitation, with host effect being the most important determinant at the regional scale.