Geographic distance and soil microbial biomass carbon drive biogeographical distribution of fungal communities in Chinese Loess Plateau soils.

Fungi are ecological drivers of carbon cycle in soils and also effectively mediate mineral nutrition for plants especially in the severely eroded Loess Plateau of China. However, factors determining variations in fungal diversity and their biogeographic patterns in this rigorously affected landscape area remain poorly understood. Therefore, we performed Illumina MiSeq high throughput sequencing of the fungal specific, internal transcribed spacer 2 (ITS2) region from 24 representative soils covering forest, grassland and agricultural lands from 8 distinct landscapes. Using this technique, we demonstrate that fungal members belonging to phylum Ascomycota dominated in all soils investigated in this study with an average relative abundance higher than 80%. High fungal richness in the Loess Plateau soils is ascribed to the retrieval of 1,822,499 quality sequences belonging to 13,533 different phylotypes. However, this richness/phylotype number decreased (from 779 to 561) with increasing longitudinal gradient through 107°39' to 109°36'. Interestingly, higher fungal diversity (in terms of presence of diverse fungal taxa) occurred as microbial biomass carbon (MBC) concentration decreased (approximately from 500 to 100mgkg) in soils. Variation partitioning analysis revealed that geographic distance contributed more to fungal community variation (38.3%) than soil properties (22.2%) at the landscape level (~400km). As indicated by non-metric multidimensional scaling (NMDS), among soil properties, concentrations of MBC primarily affected (significantly corrected with NMDS 1; r=0.620; p<0.01) fungal community structure in the current study. This study therefore constitutes an essential set of information and recommends usage of information on fungal community structure as a potential ecological indicator of the Loess Plateau region.