RESUMO
Revealing the responses of soil microbial community to soil erosion can provide guidance for agricultural ecosystem management. We investigated the impacts of soil erosion intensity on soil microbial quantity at the Binzhou River Basin, a typical thin layer Mollisol area in Bin County of Heilongjiang Province, using 137Cs tracer. The results showed that there were seasonal variations in soil microbial quantity. The abundance of soil microbes in summer was considerably higher than that in autumn. Bacteria was more sensitive to seasonal variation than fungi and actinomycetes, which was increased by 1.4-2.6 times and 1.4-2.2 times in summer compared with autumn in different parts of slope and watershed, respectively. The spatial variation of soil erosion intensity had an important effect on the spatial distribution of soil microbial community. The highest proportion of bacteria was found at lower deposition area of slope (84.4%) and at the lightly eroded area of the downstream (85.4%). The numbers of soil microbes, soil bacteria and actinomycetes were negative linearly correlated with soil erosion modulus, with correlation coefficients of -0.595, -0.554 and -0.291, respectively. Soil erosion and deposition induced spatial differences in soil physical and chemical properties, with consequences on spatial distribution of soil microbial community.
