[Effects of different aspects on soil microbial biomass and dissolved organic carbon of the loess hilly area].

Soil samples from different aspects (southern slope and northern slope) under the same vegetation in two typical vegetation zones (forest vegetation zone and steppe vegetation zone) of Yanhe basin in the loess hilly area were chosen and analyzed, in order to investigate the content and correlation of soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soil microbial biomass phosphorus (SMBP) and dissolved organic carbon (DOC). The results show that, in 0-10 cm soil layer of forest vegetation zone, SMBC in southern slope and northern slope are 532.1-792.5 mg x kg(-1) and 333.6-469.8 mg x kg(-1), SMBN are 53.66-87.31 mg x kg(-1) and 47.58-61.38 mg x kg(-1) respectively, both of them are higher in southern slope than those in northern slope, but in steppe vegetation zone, SMBC and SMBN in southern slope are lower than those in northern slope, with SMBC of southern slope and northern slope are 68.90-75.34 mg x kg(-1) and 65.29-128.67 mg x kg(-1), SMBN are 13.94-18.61 mg x kg(-1) and 13.00-20.10 mg x kg(-1) respectively, SMBP in both vegetation zones have a different variation trend compared with SMBC and SMBN; the ratio of SMBC to the sum of SMBC plus DOC (SMBC + DOC) in southern slope of forest vegetation zone reaches the maximum value in two vegetation zones, which is 77.74%. In steppe vegetation zone, this ratio both decreases from northern slope to southern slope and 0-10 cm soil layer to 10-30 cm soil layer. The difference of soil moisture and temperature between different aspects under the same vegetation have a significant effect on soil microbial biomass, it also makes the ratio of SMBC to SMBC + DOC different, SMBC + DOC can reflect soil carbon availability better than SMBC, there might be an obvious change in soil microbial communities in 0-10 cm soil layer of different aspects in forest vegetation zone.