Divergent responses of soil bacterial communities in erosion-deposition plots on the Loess Plateau

Abstract

Soil erosion and deposition occur widely from regional to global scales and have profound impacts on ecological services and sustainability. Despite their crucial roles in biogeochemical cycles, the responses of soil bacterial communities to soil erosion and deposition remain largely unclear. In this study, a field simulation experiment was conducted to examine variation in soil bacterial communities across eroding slopes and depositional zones with three slope gradients (5°, 10° and 20°) on the Loess Plateau of China (2015–2017). The results showed that soil physicochemical properties were altered by redistribution of runoff and sediment across eroding slopes and depositional zones. Soil bacterial alpha diversity was higher in the depositional zones of both 10° and 20° slopes compared with the 5° reference slopes but no markedly difference was found between eroding slopes and reference slopes. By contrast, bacterial community structure differed between eroding slopes and reference slopes but not between depositional zones and reference slopes. Differentiation of bacterial communities between eroding slopes and depositional zones increased with increasing slope gradients. The bacterial network was greater and more complex within depositional zone than eroding slope, indicating more extensive bacterial interactions and greater community stability potential. Erosion- and deposition-induced redistribution of soil moisture, soil organic matter, available P, and available K were the key determinants of variation in bacterial community structure. Our findings demonstrate the contrasting effects of soil erosion and deposition on soil bacterial communities, which should be given further attention across eroding landscapes.