| Thin layer of black soil caused by serious soil erosion at the typical watershed of blacksoil region, and soil erosion reduce the function of soil ecosystem, which seriously affectedfood production and sustainable agricultural development in this region. Currently, researchon the spatial distribution of soil microbial indicators in this basin were seldom, changes ofsoil microbial indicators can be seen as an early indication of changes in soil ecosystemfunction, which may characterize soil quality in the long run. Therefore, it is necessary tocarry out research on soil microbial indicators. Therefore, soil samples from different slopepositions of Binzhou river basin were collected to analyze the spatial distribution of soilmicrobial indicators, study the correlation among soil microbial indicators、organic matter andnitrogen, explore the relationship of spatial distribution between soil erosion-deposition andsoil microbial indicatos. The main results are as follows:(1) This paper studies characters in the average of soil microbial indicators in summerand autumn. The results showed that averages of soil microbial indicators in summer are allhigher than that of soil microbial indicators in autumn. The average of soil microbialcommunities is1.71×10~7cfu, the value is2.69times than that of in autumn; the average ofbacteria is1.47×10~7cfu, the value is2.69times than that of in autumn; the average of fungi is2.04×10~5cfu, the value is1.63times than that of in autumn; the average of actinomycetes is2.13×10~6cfu, the value is1.38times than that of in autumn. The average of SMC and SMNare1.39and2.64times than that of in autumn respectively, the average of soil respirationentropy and soil respiration rate are2.11and1.31times than that of in autumn repectively.(2) This paper analyzes the watershed distribution of soil microbial indicators in summerand autumn respectively. The results show that the distribution of microbial indicators isdifferent between summer and autumn at the watershed scale. In summer, the number of soilmicrobial communities and bacteria ranked as downstream＞mid-stream＞upper-stream atthe watershed scale, the number of fungi ranked as upper-stream＞downstream＞mid-stream,and the number of actinomycetes reached the highest value in middle of stream; the content of soil microbial biomass carbon and nitrogen ranked as upper-stream＜mid-stream＜downstream; soil basal respiration rate ranked as upper-stream＜mid-stream＜downstream,soil respiration entropy ranked as downstream＜mid-stream＜upper-stream. In autumn, thenumber of microbial communities and bacteria ranked as mid-stream＜upper-stream＜downstream at the watershed scale, and the number of fungi ranked as downstream＜mid-stream＜upper-stream, the number of actinomycetes ranked as mid-stream＜upper-stream＜downstream; the content of microbial biomass carbon and nitrogen ranked asupper-stream＜mid-stream＜downstream; soil basal respiration rate ranked as mid-stream＜upper-stream<downstream, soil respiration entropy ranked as downstream＜mid-stream＜upper-stream.(3) This paper explores slope distribution of microbial indicators in summer and autumnrespectively. The results show that the distribution of microbial indicators is different betweensummer and autumn at the slope scale. In summer, the number of microbial communities andbacteria ranked as mid-slope＜upper-slope＜downslope at the slope scale, the number offungi ranked as downslope＜mid-slope＜upper-slope, the number of actinomycetes ranked asmid-slope＜downslope＜upper-slope; the content of microbial biomass carbon and nitrogenranked as downslope＜mid-slope＜upper-slope; soil basal respiration rate ranked asmid-slope＜upper-slope＜downslope, soil respiration entropy ranked as upper-slope＜mid-slope＜downslope.In autumn, the number of microbial communities and bacteria rankedas mid-slope＜upper-slope＜downslope at the slope scale, the number of fungi ranked asmid-slope＜downslope＜upper-slope, the number of actinomycetes ranked as downslope＜mid-slope＜upper-slope; the content of soil microbial biomass carbon ranked as downslope＜mid-slope＜upper-slope, the content of soil microbial biomass nitrogen ranked as upper-slope＜mid-slope＜downslope; soil basical respiration rate ranked as mid-slope＜upper-slope＜downslope, soil respiration entropy ranked as upper-slope＜mid-slope＜downslope.(4) This paper analyzes the relationship among microbial indicators、organic matter andtotal nitrogen in summer. The results showed that: through analyzing soil microbialcommunity composition, except that there was a significantly positive relationship betweenthe number of soil bacteria and soil organic matter content, there was also a significantlynegative relationship between the number of actinomycetes and total nitrogen content, otherindicators did not reach the significantly correlative level; there was a significantly positiverelationship between the content of microbial biomass carbon and soil organic matter content,there was also a significant positive correlation between the content of microbial biomasscarbon ang soil total nitrogen content, the content of microbial biomass nitrogen hadsignificant positive correlation with soil organic matter, and significantly positive correlation with total nitrogen; through analyzing microbial activity indicators, except that soil basalrespiration and soil organic matter content had significant positive correlation, and except thatsoil organic matter content and soil respiration entropy had highly significant negativecorrelation, other indicators did not reach significant correlation.(5) This paper compares the correspondence of spatial distribution between microbialindicators and soil erosion-deposition. The results showed that: analyzing from the watershedscale, in summer, in addition to the number of fungi and actinomycetes, other microbialindicators corresponds with the spatial distribution of soil erosion-deposition; in autumn, soilmicrobial biomass carbon、microbial biomass nitrogen content and respiratory quotientcorrespond with the spatial distribution of soil erosion-deposition. At the slope scale, insummer, the number of microbial communities、bacteria、soil basical respiration correspondswith the slope distribution of soil erosion-deposition. In autumn, the number of microbialcommunities、bacteria、fungi and soil basical respiration rate corresponds with the slopedistribution of soil erosion-deposition. |
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