三峡库区不同林草措施土壤活性有机碳及抗蚀性研究

采用野外定位观测,研究三峡库区坡耕地7种林草治理措施下土壤活性有机碳组分(颗粒性有机碳、可溶性有机碳、易氧化有机碳和微生物生物量碳)含量和团聚体数量特征,并分析了团聚体的分形特征和可蚀性.结果表明,不同林草治理措施下,土壤有机碳及活性有机碳组分含量随土壤深度的增加而降低,其中0～10 cm土壤有机碳及各活性有机碳组分含量显著高于20～30 cm.林草措施治理对土壤团聚体稳定性也具有显著影响,>0.25 mm水稳性大团聚体总量总体上表现为:栾树+黄花槐>植物篱>封山育林>自然恢复>经济林>传统农作>裸地对照,且与土壤有机碳含量呈正相关.不同林草治理措施下土壤具有一定的土壤分形特性.其中栾树+黄花槐措施下土壤的分形维数、可蚀性K值最小,土壤结构稳定性和抗侵蚀能力相对较强.不同土壤深度下活性有机碳组分与土壤可蚀性K值均呈极显著负相关关系,以上研究表明通过不同林草治理措施的治理可改变土壤性状,从而影响土壤抗蚀能力.

Effects of Biological Regulated Measures on Active Organic Carbon and Erosion-Resistance in the Three Gorges Reservoir Region Soil

To gain a better knowledge of characteristics of soils and provide a scientific basis for soil erosion control in the Three Gorges Reservoir Area, contents of aggregates and total soil organic carbon(SOC), as well as soil active organic carbon fractions including particulate organic carbon(POC), readily oxidized organic carbon(ROC), dissolved organic carbon(DOC), microbial biomass carbon(MBC) in the 0-30 cm soil layer under seven different biological regulated measures were studied by the field investigation combined with the laboratory analysis. Results showed that the content of the SOC and active organic carbon fractions decreased with the increasing soil depth; the content of the SOC and active organic carbon fractions in 0-10 cm was significantly higher than that in 20-30 cm. The stability of soil aggregates were also significantly influenced by biological regulated measures, the content of >0.25 mm water-stable aggregates in seven types of biological regulated measures was in the order of Koelreuteria bipinnata + Cassia suffruticasa >hedgerows>closed forest>natural restoration>economic forest>traditional planting>control plot, moreover, the content of 0.25 mm water-stable aggregates correlated positively with the content of SOC. Soils under different biological regulated measures all demonstrated fractal features, and soil under the measure of Koelreuteria bipinnata + Cassia suffruticasa was found to have the lowest value of fractal dimension and soil erodiable K, indicating a relatively strong structure stability and erosion-resistant capacity. Negative correlation was observed when compared the content of active organic carbon fractions with the soil erodiable K. It can be concluded that properties of soil can be managed through biological regulated measures; thence had an influence on the soil erosion-resistant capacity.