三峡库区消落带不同高程桑树林地土壤抗蚀性及影响因素

Characteristics and soil anti-erodibility effects of mulberry forest lands at different altitudes of water-level fluctuation zone of the Three Gorges Reservoir

消落带是典型的生态脆弱区,研究消落带土壤抗侵蚀特点对三峡库区水土流失防治具有重要意义。为了研究三峡库区消落带桑树林地土壤抗蚀性在不同高程处的差异,本文以典型消落带桑树林地为研究对象,采用土壤理化性质研究法对不同高程桑树林地土壤抗蚀性特征及其影响因素进行了分析。结果表明：1）不同高程桑树林地0～20 cm土层土壤抗蚀性指数具有较大差异,表现为180 m（38.22%）〉170 m（23.09%）〉165 m（18.4%）〉175 m（10.5%）,且未淹没区（高程为180 m）大于淹没区（高程≤175 m）;对于同一高程,表层（0～10 cm）土壤抗蚀性优于底层（10～20 cm）。2）土壤15个抗蚀性指标优化为F1、F2、F3 3个主成分,其土壤抗蚀性综合评价模型为F=0.655F1＋0.236F2＋0.109F3,评价结果表明不同高程桑树林地土壤抗蚀性大小为180 m〉170 m〉165 m〉175 m。3）相关性分析表明土壤抗蚀性指数与土壤黏粒（〈0.001 mm）、〉0.25 mm水稳性团粒含量呈极显著正相关（P〈0.01）,相关性系数分别为0.878和0.732;与土壤有机质含量呈显著正相关（P〈0.05）,相关性系数为0.689;与砂粒和粉粒含量相关性不显著。说明黏粒、〉0.25 mm水稳性团粒和有机质是影响三峡库区消落带土壤抗蚀性的重要因子。研究结果可为三峡库区消落带不同区域土壤流失进行针对性防治提供重要科学依据。

Due to periodic wet and dry processes, water-level fluctuation zone of the reservoir area is typically ecologically fragile. It is therefore important for protection of the eco-environments of reservoir areas to control soil and water loss in such specifically fragile zones. Mulberry forest plots were selected in the water-level fluctuation zone of the Three Gorges Reservoir in September 2012 at four altitudes（165 m, 170 m, 175 m and 180 m）, with no flooding at the 180 m altitude. Soil physio-chemical characteristics, anti-erodibility and the driving factors of mulberry forest lands at different altitudes were studied. The aim of the study was to explore soil anti-erodibility effect of mulberry forests at different altitudes. The study further provides scientific basis for controlling soil and water loss in the reservoir area. Results suggested that soil anti-erodibility indexes for the 0-20 cm soil layer of mulberry forest lands at different altitudes were greatly different, and were in the order of 180 m（38.22%）〉 170 m（23.09%） 〉165 m（18.4%）〉 175 m（10.5%）. Soil anti-erodibility index was greater for unsubmerged area than submerged areas. For the same altitude, soil anti- erodibil-ity index of the 0-10 cm layer was higher than that of the 10-20 cm layer. Fifteen indicators of soil anti-erodibility were optimized to 3 principal components ― F1, F2 and F3. The comprehensive evaluation model of soil anti-erodibility index was F = 0.655F1 ＋ 0.236F2 ＋ 0.109F3. Based on the comprehensive model evaluation, soil anti-erodibility was ranked as 180 m 〉170 m〉 165 m 〉175 m. Correlation analysis showed that soil anti-erodibility index had significant positive correlation（P〈0.01） with soil clay content and greater-than 0.25 mm water stable aggregate content, with respectively correlation coefficients of 0.878 and 0.732. A significant positive correlation was observed between soil anti-erodibility index and organic matter content, with a correlation coefficient of 0.689. There was no significant correlation between soil anti-erodibility index and sand or silt content. It was concluded that soil clay, greater-than 0.25 mm water stable aggregate and organic matter were the key factors influencing soil anti-erodibility in the water-level fluctuation zone of the Three Gorges Reservoir area.