【作者】 朱远达；

【导师】 张光远； 蔡强国；

【作者基本信息】 华中农业大学 ， 土壤学， 2001， 硕士

【摘要】 土壤侵蚀对土壤生产力的影响是当前水土保持领域界的研究热点。土壤侵蚀主要通过影响土壤养分含量来影响土壤生产力。本研究以三峡库区秭归县水田坝乡王家桥小流域四个径流试验区二十个标准小区为研究对象，通过坡形实地测量、坡面密集采样的颗粒分析和养分含量分析以及人工模拟降雨实验，研究了土壤侵蚀对土壤碳和养分的影响途径和表现，侵蚀作用影响下土壤碳和养分在微地形空间的分布规律；同时，在地理信息系统的支持下，建立了侵蚀条件下的土壤碳和养分变化模型，模拟了侵蚀对土壤碳和养分影响的空间过程，预测了侵蚀影响下土壤碳和养分的年变化及多年变化，并通过研究建立的模型对不同侵蚀控制措施进行了初步的效益评价。本研究的主要目的是探明土壤侵蚀对土壤碳及养分含量影响的表现、途径和过程，并在空间上模拟其动态过程，最后提供一种较为精确计算土壤侵蚀影响下土壤碳和养分含量变化的途径，从而为侵蚀治理、规划、设计以及生态环境建设提供了理论依据和实践指导。 研究中，在前人基础上紧跟研究前沿，主要得出如下成果和创新点： 一、明确了侵蚀作用影响土壤碳和养分含量的具体表现：经过实地测量、采样颗粒分析和养分分析，结果表明，在不同培肥、不同耕作、不同坡度以及不同侵蚀控制条件下，受侵蚀及堆积作用强弱的影响，微地形形态、土壤颗粒组成、碳和养分含量在空间上都可能出现较大的分布差异。 二、明确了侵蚀作用影响土壤碳和养分含量的具体途径：分析表明，侵蚀作用使坡面土壤中大于0.2mm的颗粒含量相对增高，而大量富集养分的、小于0.02mm的颗粒含量则相对减少，从而影响了养分在坡面上的再分配。人工降雨实验结果表明，在降雨强度和侵蚀强度不大时，侵蚀泥沙是全量养分流失的主体，地表径流则是速效养分流失的主体；而当在降雨强度和侵蚀强度极为剧烈时，侵蚀泥沙成为全量养分和速效养分二者流失的主要载体；地表径流中的养分含量很大程度上受土壤中养分含量的影响，土壤中养分含量越高，养分径流流失的可能性越大。 三、在流域空间范围内描述了侵蚀影响土壤碳和养分的现状：在地理信息系统的支持下，模拟了流域各地块的侵蚀过程、现状，充分描述了各个地块在侵蚀影响下土壤碳和养分的年变化现状、过程及多年变化过程，得到在现有侵蚀及耕作管理条件下，全流域中土壤碳、全氮、全磷、全钾下降的地块面积分别占流域总面积的44.1％、55.8％、39.2％、75.7％，以及各个地块的碳和养分含量变化趋势，弥补了前人研究在地域华中农业大学2001届硕士研究生学位论文空间联系上的不足。 四、得到了引起土壤碳和养分发生变化的侵性模数阀值:通过对地块土壤侵蚀模数、碳和养分含量变化的计算，得到了不同利用类型中不同元素含量出现下降的最低侵蚀模数阀值，如耕地全氮为2000一2500吨，果园全氮为3000一3500吨，林地全氮为1000一1500吨，草地全氮为1000-1500吨，从而为流域侵蚀治理规划和生态环境建设提供了科学依据。 五、应用模型预测了土壤碳和养分的长期变化，并对相关规划设计作出了评价:以侵蚀模数大于2000t/匆mZ的坡耕地为例，计算了侵蚀控制后和控制前的碳和养分十年变化状况，得出在现有耕作管理条件不变的情况下，将坡耕地侵蚀模数控制在ZooQ口kmZ时，即可基本控制坡耕地土壤碳和养分含量下降的局面。最后.，就维持土壤碳和养分效益方面，计算比较了坡改梯、坡地布设植物篱两种治理方案的优劣，认为布设植物篱方案对维持土壤碳和养分具有更好的效果，将大大缩短投资回收年限。更多还原

【Abstract】 It is one of hotspots in soil erosion researching that how soil erosion affects soil productivity. Generally, its main approach is affecting contents of soil organic matters and nutrient. Through measuring slope forms on the spot, serried sampling, physical and chemical analyzing, and measuring soil erosion from natural and artificial rainfalls, the project researched in the approaches and behaviors of soil erosion affecting contents of soil carbon and nutrient, and the law of soil carbon and nutrient distributing in micro-topographty under influences of soil erosion. In the same time, supported by Geographic Information System, models of soil carbon and nutrient changing with soil erosion have been built, and spatial processes of soil erosion affecting soil carbon and nutrient have been simulated, and annual and long-term changing of soil carbon and nutrient under impact of soil erosion have been estimated and forecasted, and synchronously, a elementary assessment for different soil erosion management has been performed by using the models built in the study. The main objectives of the study are illustrating behaviors, approaches and processes of soil erosion affecting contents of carbon and nutrient in soil, and simulating its dynamic changing in spatial scale, and providing a methods of estimating content changes of carbon and nutrient under the affluences of soil erosion to guide the practices of soil erosion control, management andprogramming.Knowledge and conclusions educed from the study are following: Firstly, actual behaviors of soil erosion on affecting soil quality have been described. Comparisons of landform measurements on the spots, and results of physical and chemical analyzing indicated that micro-iandform, proportions of soil particles sizes, and contents of soil carbon and nutrient have differences of spatial distribution under different conditions of fertilization development, cultivation, slope, and soil erosion management, which are closely related to intensities of soil erosion and sediment deposition.Secondly, approaches by which soil erosion affects soil quality have been illustrated and confirmed. Results of analysis indicated that, erosion increases correspondingly the particles (>0.2mm) of soil, while the particles (<0.02mm) correspondingly decreased. As the particles (<0.02mm) have enriched nutrient, the redistribution of carbon and nutrient is affected by erosion. Experiments of artificial rainfall showed that sediment is the main body of total nutrient loss and runoff is the main body of available nutrient loss when erosion is slight, but sediment become the main body of total and available nutrient synchronously while erosion is intense. Concentration of nutrient in runoff is most likely to be affected by concentration in topsoil. The higher concentration in topsoil is, the more possible nutrient loss by runoff is.Thirdly, present status of effect of erosion on soil carbon and nutrient has been illustrated in spatial scale of the watershed. Based on Geographic Information System, actuality and process of soil erosion in and between land units were simulated, and actuality and process of annual and long term changing of soil carbon and nutrient in each land unit under erosion were sufficiently calculated and illustrated. Results of simulation and illustration showed that, the relative area in which soil carbon, nitrogen, phosphorus and potassium is deceased is 44.1%, 55.8%, 39.2% and 75.7% respectively. All these results remedied the deficiency of spatial relationship in previous studies.Fourthly, critical value of erosive modulus, which may cause soil carbon and nutrient changing, has been taken. The results of simulation showed that different soil nutrient element(C, N, P, K) have different soil acceptable erosive modulus in different land use types. For example, in this study, the critical value for Nitrogen is located in the range of 1500-2000t/km2for forest land, 2000-2500 t/km2 for tillage land, 2500-3000 t/km2 for garden land, and 1000-1500 t/km2. for grassl更多还原