Landscape context determines soil fungal diversity in a fragmented habitat

Habitat fragmentation is a primary cause of biodiversity loss. As an essential part of the ecosystem, soil microorganisms participate in a series of ecosystem processes. However, the role of landscape factors on soil microorganisms is not well understood. Based on high-throughput sequencing of soil samples at three depths (0-10 cm, 10-20 cm, 20-30 cm) from 30 landscape sites along a habitat fragmentation gradient, we calculated soil bacterial and fungal diversity in the agm-pastoral ecotone of northern China. We then investigated the impact of climatic factors, soil characteristics, and landscape context (patch density, edge density, mean patch size, and mean nearest-neighbor distance) on soil bacterial and fungal diversity. We found that soil fungal richness increased with habitat fragmentation (patch density and edge density), although soil bacterial richness did not change significantly. Soil bacterial and fungal community composition both changed with habitat fragmentation. Soil characteristics were key factors determining soil bacterial diversity, especially in the 10-20 cm soil depth. Soil fungal diversity was closely related to landscape context, showing a significant positive correlation with patch density and edge density, and a significant negative correlation with mean patch size. Structural equation modeling showed that landscape factors directly affected soil fungal diversity but indirectly affected soil bacterial diversity by changing soil characteristics. We highlight that soil fungal diversity shows an increasing trend with increased habitat fragmentation. Landscape context plays a stronger role in maintaining soil fungal diversity than soil characteristics and climatic factors.