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选取黄土高原丘陵沟壑区延河流域两个典型植被区(森林植被区、草原植被区)下相同植被不同坡向(阳坡、阴坡)的土样进行分析,研究了不同坡向土壤微生物生物量碳(SMBC)、微生物生物量氮(SMBN)、微生物生物量磷(SMBP)和可溶性有机碳(DOC)的含量及其相互关系.结果表明,森林植被区阳坡、阴坡0～10 cm土层SMBC分别为532.1～792.5 mg·kg-1、333.6～469.8 mg·kg-1,SMBN分别为53.66～87.31 mg·kg-1、47.58～61.38 mg·kg-1,两者均表现为阳坡高于阴坡,草原植被区SMBC分别为68.90～75.34 mg·kg-1、65.29～128.67 mg·kg-1,SMBN分别为13.94～18.61 mg·kg-1、13.00～20.10mg·kg-1,两者均表现为阴坡高于阳坡;两个植被区SMBP与SMBC、SMBN变化不一致;SMBC占SMBC与DOC之和(SMBC+DOC)的比例在森林植被区阳坡最高,达77.74%,在草原植被区按阴坡到阳坡、0～10 cm土层到10～30 cm土层的顺序依次递减.相同植被区不同坡向土壤水分、温度的差异对土壤微生物生物量产生重要影响,进而使SMBC占SMBC+DOC的比例不同,SMBC+DOC比SMBC更能反映土壤碳素有效性,森林植被区阴坡阳坡0～10 cm土层土壤微生物群落结构可能已发生明显改变.
The soil samples of different slope (sunny slope and shady slope) of the same vegetation under two typical vegetation zones (forest vegetation zone and grassland vegetation zone) of Yanhe River Basin in the hilly-gully region of the Loess Plateau were selected for analysis. Soil microbial communities (SMBC), SMBN, SMBP and DOC of the forest were studied.The results showed that the sunny slopes and shady slopes of 0 ~ 10 cm Soil SMBC were 532.1-792.5 mg · kg -1,333.6 ~ 469.8 mg · kg -1, and SMBN were 53.66 ~ 87.31 mg · kg -1,47.58 ~ 61.38 mg · kg -1, respectively, both of which were positive The SMBC of grassland vegetation area were 68.90-75.34 mg · kg-1 and 65.29-128.67 mg · kg-1, respectively, SMBN were 13.94-18.61 mg · kg-1 and 13.00- 20.10 mg · kg-1, respectively , Both showed shady slopes higher than the sunny slopes. SMBP, SMBC and SMBN in the two vegetated areas varied inconsistently. The ratio of SMBC to SMBC and DOC (SMBC + DOC) was highest in the sunny slope of the forest vegetation area, reaching 77.74% , Decreasing in descending order from shady slopes to sunny slopes and from 0 ~ 10 cm soil layers to 10 ~ 30 cm soil layers in the order of shady vegetation area.The soil moisture and temperature in different slopes of the same vegetation area SMBC + DOC ratio of SMBC + DOC is more than that of SMBC, the soil carbon availability of SMBC + DOC is better than that of SMBC, Microbial community structure may have changed significantly.