三峡库区不同退耕还林模式水土保持效益定位监测

Located Monitoring of Soil and Water Conservation Benefits of Different Reforestation Patterns in Three Gorges Reservoir Region

摘要:

摘要：选择三峡库区内4种典型退耕还林模式，基于2004，2007，2010年3年的定位观测，对三峡库区退耕还林模式水土保持效益进行动态研究。结果表明：①与坡耕地相比，退耕还林促使土壤容重降低、孔隙度增加，但各模式变化存在差异。②地表径流量、径流系数、土壤侵蚀模数均呈现明显的降低趋势，其中地表径流平均减少量80.43%～86.82%，变化趋势为坡耕地＞茶园＞刺槐林＞板栗林＞柑橘+紫穗槐林；径流系数变化减少范围在0.017～0.025之间，柑橘+紫穗槐林86.79%、板栗林85.39%、茶园83.33%、刺槐林80.95%；土壤侵蚀模数减少1 409.39～1 458.15 t·（km2·a）-1，为坡耕地＞刺槐林＞板栗林＞茶园＞柑橘+紫穗槐林。③随着退耕年限的增加，除了板栗林表现为逐渐升高外，其他退耕还林模式土壤有机质含量均表现为先降低后升高。全氮含量在刺槐林和柑橘+紫穗槐林表现为先降低后升高，而板栗林和茶园则表现为逐渐增加的趋势。全磷含量在各退耕模式中不断增加。除柑橘+紫穗槐林的全钾含量增加35%外，其他模式都逐渐降低，分别为刺槐林37.24%、板栗林12.33%、茶园8.23%。

Abstract:

Abstract:We chose four typical patterns of converting farmland to forest in Three Gorges Reservoir region as study subject, which were Robinia pseudoacacia,Citrus reticulata+Amorpha fruticosa,Castanea mollissima,tea plantation, and chose slope land as reference.Based on the located observation of 3 years including 2004, 2007 and 2010，the dynamic change on soil and water conservation benefits of the patterns of converting farmland to forest was studied. Here come the conclusions: ① Compared with the slope farmland, the soil bulk density of four different patterns of converting farmland to forest decreased, and the porosity increased,but there were differences among different patterns. ② Surface runoff,runoff coefficient and soil erosion modulus for the four different modes of converting farmland to forest had a obvious significant decreasing trend. The average reduction for surface runoff was 80.43%～86.82%,the trend showed farmland＞tea plantation＞Robinia pseudoacacia＞Castanea mollissima＞Citrus reticulata + Amorpha fruticosa.The runoff coefficient for every mode of returning farmland to forest land ranged from 0.017 to 0.025, The reduce number for different mode varied as Citrus reticulata+Amorpha fruticosa(86.79%),Castanea mollissima(85.39%), tea plantation (83.33%),Robinia pseudoacacia (80.95%) respectively. The average reduction for soil erosion modulus was 1 409.39～1 458.15 t·（km2·a）-1, the trend showed farmland＞Robinia pseudoacacia＞Castanea mollissima＞tea plantation＞Citrus reticulata+Amorpha fruticosa.③ With the increasing of farmland returning, except that the soil organic matter of Castanea mollissima showed a gradual increasing,that of other patterns decreased at first and then increased.The total nitrogen content of Robinia pseudoacacia and Citrus reticulata+Amorpha fruticosa firstly decreased and then increased, while that of Castanea mollissima and tea plantation showed a gradually increasing trend. And the total phosphorus content increased continuously in all typical patterns of converting farmland to forest.Except that the total potassium content of Citrus reticulata+ Amorpha fruticosa increased 35%,that of other modes gradually reduced, which values were Robinia pseudoacacia(37.24%), Castanea mollissima(12.33%), and tea plantation (8.23%) respectively.