【作者】 马志林；

【导师】 周心澄； 王治国；

【作者基本信息】 北京林业大学 ， 工程绿化， 2009， 博士

【摘要】 占总面积66.3%的山区旱坡地是三峡库区江河泥沙的主要来源,为了控制三峡库区水土流失,科技人员对三峡库区坡耕地土壤侵蚀进行了大量的调查研究,但对于构建不同植被类型下的水土流失特征及其生态效应研究还停留在定性描述的阶段。本文以三峡库区几种典型植被治理类型为对象,通过大量的实地调查和定位观测试验,系统研究了不同植被类型下坡耕地水土流失的主要影响因子、特征、规律及其土壤理化性质变化情况,并对不同生态治理类型的生态效益进行了综合评价。观测分析表明,三峡库区坡耕地不同植被类型泥沙和径流流失规律基本一致,水土流失主要发生在几个关键月份,4、8、9月累积径流流失共占全年总流失量的83.53%,泥沙流失共占全年的98.55%。径流和泥沙流失程度最轻的均为水土保持型,其次是生物篱类型和生态经济林类型,最重的是裸地。典型降雨对径流和泥沙流失都具有决定性作用,3次典型降雨累积泥沙流失量占流域年总量的90.28%,径流流失量占63.28%。雨后泥沙和雨前表土颗粒变化表明,泥沙对细颗粒,即＜0.25mm的微团聚体和＜0.001mm的粘粒具有富集特征。灰色相关分析表明,各降雨因子对不同植被类型径流和泥沙流失的影响,总的表现为:对径流流失的影响,降雨量（Y₁）最大,其次是最大30min雨强（Y₄）和降雨强度（Y₃）,降雨历时（Y₂）影响程度最小;对泥沙流失的影响,降雨历时（Y₂）最大,其次是降雨强度（Y₃）,影响最小的是最大30min雨强（Y₄）和降雨量（Y₁）。对不同植被类型坡耕地径流流失、泥沙流失与次降雨侵蚀力、次降雨量之间的相关模型分析表明,其间存在着不同的函数关系。不同植被类型降雨后表土各养分含量均低于雨前表土养分含量,而且速效氮、磷、钾的衰减幅度大于全量养分。泥沙中0.05～0.001mm的粉粒和＜0.001mm的粘粒是表土中养分流失的主要附着颗粒（载体）。且泥沙中各养分浓度明显大于表层土壤,远远大于径流,径流中养分浓度很小。但由于三峡库区雨量充沛,径流量是泥沙量的20倍以上,所以随径流流失的养分量也不容忽视,应视为径流和泥沙两者共同携带养分流失。不同农业耕作制度下,雨季不同地面覆盖度与该期土壤侵蚀量呈明显的负相关性。5～9月平均覆盖度,以两熟制小麦-红薯最低,只有50.72%,三熟制均达到70%以上,三熟制流失量明显小于二熟制。不同生态治理类型,随着时间的变化,土壤特性呈现有规律的良性发展趋势,即土壤容重逐渐减小,土壤孔隙度逐渐增大,且均优于裸地。不同植被类型土壤平均持水能力为157.69m³/hm²,是裸地持水能力（60.97m³/hm²）的2.59倍;持水能力由大到小依次为竹林＞茶林＞紫穗槐＞金荞麦＞板栗退耕＞针阔混交林＞马尾松林＞板栗间种。不同植被类型在不同时期或同一时期表层土壤（0～10cm）养分含量均表现出一定的变化规律,土壤颗粒粒径变化也较大。综合分析发现,竹林对土壤的物理性状改善比较大,其次是针阔混交林、马尾松林和紫穗槐。模糊综合评价表明,不同植被类型综合生态效益,生态经济林复合类型＞水土保持林类型＞生物篱类型＞农耕地,且三种生态治理类型林地均为坡耕地的3倍左右。说明生态经济林复合类型、水土保持林类型和植物篱类型的实施,对三峡库区生态环境的改良作用十分明显。今后还要不断加强理论和应用推广研究,为库区水土流失治理提供支撑。更多还原

【Abstract】 Arid mountain slopes land of 66.3%of the total area in Three Gorges reservoir area is a major source of river sediment,in order to control soil and water erosion of Three Gorges reservoir area,a lot of investigation and research of soil erosion of slope land have been taken by the scientific and technical personnel.But the study of soil erosion characteristics and the ecological effects to build under the ecological control pattern also remained at the stage of qualitative description.In this paper,taking several typical control types of Three Gorges reservoir area as the example,the effect factors, characteristics and rules of the soil erosion and its diversification of the soil physical and chemical properties under different vegetation types were studied by large numbers of pilot field survey and positioning observation.And different ecological control types for the ecological benefits were comprehensively evaluated.Observation analysis showed that the sediment loss rules were basically the same as the runoff loss under different vegetation types of the slope land of Three Gorges reservoir area.Soil and water erosion of arable land occurred mainly in a few critical months.The cumulative runoff loss of April,August and September occupied 83.53%of the annual total loss,and sediment loss was 98.55%of the annual total loss.The extent of runoff and sediment loss indicated that:the lightest type was soil and water conservation;the followed was biological fence pattern and ecological forest model;and the most serious one was the bare land.In addition,the typical rainfall played a decisive role to runoff and sediment loss.It showed that 90.28%sediment loss and 63.28%runoff loss in total was accumulated after three times typical rainfall of a year.The change of topsoil particles of before and after the rain showed that the＜0.25mm sand agglomerates and the＜0.001mm clay particle had the enriched characteristics.According to the grey correlation analysis,the impact of runoff and sediment loss of different vegetation types from the factors of rainfall showed that:to the impact of the runoff,rainfall（Y₁） was the largest;followed by 30min largest rainfall intensity（Y₄） and rainfall intensity（Y3）;rainfall duration （Y₂） was the minimum impact.In addition,to the impact of the sediment,rainfall duration（Y₂） was the largest;followed by rainfall intensity（Y₃）;the impact of the 30min largest rainfall intensity（Y₄） and rainfall（Y₁） were the smallest.On the correlation model analysis between runoff and sediment loss and rainfall erosivity and sub-rainfall of different vegetation types,it showed that there were different functions. The nutrient content of surface soil after rainfall was lower than that before rainfall under different vegetation types.Also the decay extent of available nitrogen,phosphorus and potassium was greater than the total nutrient content.Sediment of 0.05～0.001mm and＜0.001mm in the silt was a major adhesion particles（cartier） for the nutrient loss of the surface soil.Even the nutrient concentrations in sediment were bigger than the topsoil and were far greater than the runoff which was in much lower concentrations.However,the amount of runoff was 20 times more than sediment in the Three Gorges reservoir area due to abundant rainfall.So the nutrients loss of runoff can not be ignored and should be regarded as the nutrient loss with the sediment loss together.The correlation between ground cover and soil erosion was significant negative during the different rainy season under different agricultural systems.According to the average coverage from May to September,that of the two-cropping of wheat-sweet potato was only 50.72%which was the lowest.The average coverage of triple cropping system was more than 70%.So the soil erosion of triple cropping system was significantly less than the loss of the two cropping system.Among different vegetation types,soil characteristics had a positive development trend as the time was changed.It was found that:soil bulk density decreased;and soil porosity increased gradually.Also all of them were better than bare land.The average soil water-holding capacity of different vegetation types was 157.69m³/hm²,which was 2.59 times of that of bare land（60.97m³/hm²）.The descending rule of water-holding capacity was that:bamboo＞Tea＞Amorpha fruticosa＞Golden buckwheat＞Chestnut of return farmland＞mixed forest＞pine forest＞chinese chestnut Intercropping.Under different ecological control models,the nutrient content of the surface soil（0～10cm） at different time or during the same period showed some variation rules.The soil particle size changed clearly as well.Comprehensive analysis found that the bamboo played a more important role on improving the physical properties of the soil.And the second of that were mixed forest,pine forest and Amorpha fruticosa.Fuzzy comprehensive evaluation showed that the integrated eco-efficiency of different vegetation types had the following rules:ecological economic forest complex types＞water and soil conservation forest types＞biological fence pattern＞farmland.Even the eco-efficiency of the three ecological control types was three times of slope land.The result indicated that the implementation of the three ecological control models played a essential role in making better the environment of Three Gorges reservoir area.Furthermore,theoretical and applied research should be strengthened in order to provide support for preventing water and soil erosion in the Three Gorges reservoir area.更多还原