Changes in fungal diversity and key-stone taxa along soil-eroding catena

Abstract

Fungal communities play an important role in soil biogeochemical cycles and ecosystem function. The redistribution of water and soil causes significant differences in the soil physicochemical properties in eroding landscapes. However, changes in soil fungal diversity and key-stone taxa in soil-eroding catena remain poorly understood in these landscapes. In the current study, the diversity and key-stone taxa of the fungal community in topsoil samples were analyzed from three typical erosive topographic units (autonomous, transitional, and depositional zones). The Chao 1 index showed a decrease from the autonomous and transitional zones (1759.7 and 1752.6, respectively) to the depositional zone (1535.3), but there were no significant differences in the Shannon index. Transitional and depositional networks had fewer edges (318 and 387, respectively) and clustering coefficients (0.236 and 0.301, respectively) than the autonomous network (911 and 0.362, respectively). At the phylum level, the nutritional strategists of key-stone taxa tended to shift from r- to K-strategists along the soil-eroding catena, indicating that the majority of key-stone taxa were dominated by the phylum Ascomycota in the autonomous and transitional zones, whereas the phylum Basidiomycota was dominant in the depositional zone. The recalcitrant carbon composition (CC/CO, autonomous vs. transitional vs. depositional: 3.82 vs. 5.09 vs. 7.52) may have contributed to the decreased fungal richness along the soil-eroding catena. The primary controlling factors affecting key-stone taxa were soil organic carbon (SOC), total nitrogen (TN) and Olsen-P in the autonomous zone, SOC and CH/CO in the transitional zone, and CC/CO in the depositional zone. Exploring the changes in fungal diversity and key-stone taxa among different erosive topographic units can contribute to an in-depth understanding of the biogeochemical cycle in the eroding environment.