水库消落带不同海拔狗牙根草地土壤可蚀性研究
杨 玲1,2,贺秀斌1,鲍玉海1,郑晓岚1,2,宋 娇1,3,李进林1,2

(1.中国科学院、水利部 成都山地灾害与环境研究所山地表生过程与生态调控重点实验室,成都 610041; 2.中国科学院大学,北京 100049; 3.重庆师范大学 地理与旅游学院,重庆 401331)

土壤可蚀性K值; EPIC模型; 草地; 空间分异; 水库消落带

Soil Erodibility of Cynodon dactylon Grassland at Different Altitudes in the Reservoir Riparian Zone
YANG Ling1,2,HE Xiubin1,BAO Yuhai1,ZHENG Xiaolan1,2,SONG Jiao1,3,LI Jinlin1,2

(1.Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,China; 2.University of Chinese Academy of Sciences,Beijing 100049,China; 3.School of Geography and Tourism Science,Chongqing Normal University,Chongqing 401331,China)

soil erodibility K value; EPIC model; grassland; spatial variation; reservoir riparian zone

备注

土壤可蚀性K值对土壤侵蚀定量研究具有重要意义,目前消落带土壤可蚀性研究较为缺乏。采集了三峡水库典型消落带不同海拔狗牙根草地0—20 cm表层土壤,并以180 m海拔未淹水的狗牙根草地为对照,采用EPIC模型计算了各海拔样地土壤可蚀性K值,分析了K值的空间分异规律,并探讨了土壤颗粒组成、水稳定性团聚体含量、有机质等对其的影响。结果发现:(1)表层(0—20 cm)土壤黏粒含量、体积分形维数、大于0.25 mm水稳性团聚体和有机质含量均低于对照,且随海拔升高而增加; 0—10 cm土层土壤有机质高于10—20 cm土层,而0—10 cm土层土壤黏粒含量和>0.25 mm水稳性团聚体含量则显著低于10—20 cm土层;(2)表层(0—20 cm)土壤可蚀性K值为0.049 6～0.061 2,均值为0.054 1,比未淹水对照高7.33%,属于高可蚀性土壤; K值随海拔升高而降低; 0—10 cm土层的K值低于10—20 cm土层,但两者无显著差异(p>0.05);(3)土壤可蚀性K值与土壤黏粒含量、>0.25 mm水稳性团聚体含量和有机质含量呈极显著负相关(p<0.01),与土壤颗粒的体积分形维数呈负相关,与土壤粉粒和砂粒含量呈正相关。综上,可通过消落带植被恢复防止波浪和降雨径流对表层土壤黏粒含量的冲刷,改良土壤结构,增加有机质含量,从而有效降低土壤可蚀性。
The K value of soil erodibility is of great significance to the quantitative study of soil erosion. At present,research on soil erodibility in the reservoir riparian zone is relatively scarce. In this study,0—20 cm topsoils of Cynodon dactylon grassland at different altitudes in the typical riparian zone of the Three Gorges Reservoir were collected,and the soil in Cynodon dactylon grassland at 180 m altitude was used as the control. The soil erodibility K values of the sample plots at different altitudes were calculated by EPIC model,and the spatial variation of K values was analyzed. Meanwhile,the effects of soil particle composition,waterstable aggregate content and organic matter on the K values were discussed. The results show that:(1)the content of clay,volumetric fractal dimension,water-stable aggregates(>0.25 mm)and organic matter in the surface layer(0—20 cm)are lower than those in the control(180 m),and increase with the elevation; the soil organic matter content in the 0—10 cm layer is higher than that in the 10—20 cm layer,while the clay content and water-stable aggregates(>0.25 mm)in the 0—10 cm layer are significantly lower than those in the 10—20 cm layer;(2)K value in the 10—20 cm layer ranges from 0.049 6 to 0.061 2 with an average value of 0.054 1,which is 7.33% higher than that of non-flooded control,belonging to high erodibility soil; the results also show that the K values decrease with the increase of altitude,and K value of 0—10 cm soil layer is lower than that of 10—20 cm layer,but there is no significant difference between them(p>0.05);(3)K value is significantly negatively correlated with the contents of soil clay,water-stable aggregates(>0.25 mm)and organic matter,negatively correlated with the volumetric fractal dimension of soil particles,and positively correlated with the contents of silt and sand. In conclusion,the vegetation restoration in the riparian zone can prevent the erosion of wave and rainfall runoff on the clay content of surface soil,improve the soil structure and increase the content of organic matter,so as to effectively reduce the soil erodibility.