黄土高原4种典型植被对土壤活性有机碳及土壤碳库的影响

对黄土高原丘陵沟壑区4种典型植被(荒草地、文冠果林地、柠条灌丛、沙棘林地)进行了活性有机碳(MBC,Microbial Biomass Carbon;EOC,Easily Oxidated Carbon;POC,Particle Organic Carbon)及有机碳的测定,结果表明:4种植被土壤活性有机碳含量随着土层深度的增加呈逐渐降低的趋势,土壤有机碳为文冠果林地荒草地沙棘林地柠条灌丛,且差异显著(P0.05)。荒草地0—40 cm范围内土壤MBC含量分别比文冠果林地、柠条灌丛、沙棘林地显著降低了8.61%、23.84%、41.42%(P0.05);荒草地土壤POC含量分别比文冠果林地、沙棘林地降低了14.47%、16.67%,比柠条灌丛POC高出了25.00%;但荒草地土壤EOC含量、碳库活度及碳库管理指数均显著高于其他3种植被类型(P0.05)。4中植被类型中沙棘林地土壤微生物熵(SME,Soil Microbial Entropy)最大,而柠条灌丛土壤有机碳储量最小。土壤SOC与土壤EOC、有机碳储量(SOCS,Soil Organic Carbon Storage)显著相关(P0.05),而土壤SOC与POC呈极显著的相关(P0.01);土壤EOC与土壤POC显著相关(P0.05),但土壤MBC与SOC、POC、EOC、SOCS均呈现出不同程度的负相关性。因此土壤活性有机碳能客观反映土壤肥力和土壤质量的变化情况,是描述土壤质量和评价土壤管理的重要指标。

Effects of four typical vegetations on soil active organic carbon and soil carbon in Loess Plateau

We determined active organic carbon (microbial biomass carbon, MBC; easily oxidized carbon, EOC; and particle organic carbon, POC) and organic carbon in four typical vegetations (grassland, Xanthoceras sorbifolia, Caragana korshinskii shrub, and Hippophae rhamnoides) in the hilly-gully region of the Loess Plateau. The results showed that the soil organic carbon content during planting gradually decreased as the soil depth increased, Xanthoceras sorbifolia > grassland > Caragana korshinskii shrub > Hippophae rhamnoides, and the difference was significant (P < 0.05). The soil MBC content in the 0-40 cm soil layer of the grassland was significantly lower than that in Xanthoceras sorbifolia, Caragana korshinskii shrub, and Hippophae rhamnoides by 8.61%, 23.84%, and 41.42%, respectively (P < 0.05). The POC content in the grassland soil was 14.47% and 16.67% lower than that in Xanthoceras sorbifolia and Hippophae rhamnoides, respectively, and 25% higher than that in Caragana korshinskii shrub; however, the EOC content, carbon activity, and carbon management index were significantly higher in the grassland than in the other three vegetation types (P < 0.05). The soil microbial entropy(SME) of Hippophae rhamnoides in the four vegetation types was the highest, and soil organic carbon of Caragana korshinskii shrub was the lowest. Soil SOC was extremely significantly correlated with soil EOC,soil organic carbon storage (SOCS) (P < 0.05), whereas soil SOC was significantly correlated with POC (P < 0.01) and soil EOC with soil POC (P < 0.05). However, soil MBC and SOC, POC, EOC, and SOCS showed different degrees of negative correlation. Therefore, soil active organic carbon can objectively reflect the changes in soil fertility and quality, and it is an important index to describe soil quality and evaluate soil management.