【作者】 张海涛；

【导师】 宫渊波；

【作者基本信息】 四川农业大学 ， 水土保持与荒漠化防治， 2013， 硕士

【摘要】 随着人类对自然的改造程度日益加深,水土流失问题逐渐凸显出来,严重制约了人类发展,目前水土流失已成为世界头号生态环境问题。本试验利用人工模拟降雨装置,以3个坡度(10。、20。、30。)、3类雨强(10mm/h、20mm/h、30mm/h)、4种植被盖度(裸地、30%、50%、80%)为变量因子,探讨在不同条件下四川盆地紫色土土壤可溶性碳(DOC)和土壤可溶性氮(DON)随径流流失量的变化。旨在探究土壤可溶性养分流失规律,为水土流失治理提供相关参考依据。通过试验主要得出了以下结论：(1)地表不同植被覆盖度对土壤可溶性碳和可溶性氮流失的影响土壤DOC和DON在相同雨强、相同坡度条件下,径流携带流失量整体变化趋势为随植被覆盖度增加而减少。其中裸地径流小区DOC和DON流失量均为最大,与裸地相比,随着植被盖度增加,另外3个径流小区DOC平均流失量分别减少3.5%、5.76%、7.39%,DON平均流失量分别减少7.78%、10.84%、14.33%。(2)不同坡度对土壤可溶性碳和可溶性氮流失的影响在相同植被盖度、相同降雨强度条件下土壤DOC、DON流失量随坡度增大而增加。坡度从10。增加至20。时,DOC流失量分别增加6.1%,DON流失量增加96.25%；当坡度从20。提升至30。时,DOC流失量增加10.97%,DON流失量增加24.41%。DOC流失速率在第2次坡度增加过程时提升较快,而DON流失量则在10。至20。时变化最大。(3)不同雨强对土壤可溶性碳和可溶性氮流失的影响土壤DOC和DON在相同植被盖度、相同坡度条件下流失量随降雨强度的增大而增大。本试验模拟了小雨、中雨、大雨3类雨强模式,试验结果表明大雨强下DOC和DON流失量均大幅度高于中雨和小雨流失量。与小雨强DOC流失量相比,中雨和大雨分别增加2.94%、13.56%；与小雨强DON流失量相比,中雨和大雨分别增加7.89%、18.44%。说明当降雨强度超过一定值时,雨强成为影响水土流失强度的主要因素。(4)不同土壤含水率对土壤可溶性碳和可溶性氮流失的影响土壤前期含水率直接影响土壤水分下渗能力。下渗能力越弱,表层土壤就越容易形成地表径流,地表径流是土壤水力侵蚀的根本。本试验对比相同降雨强度、坡度、植被盖度后发现,土壤高含水率条件下其DOC流失量比低含水率条件下增加5.75%；DON流失量增加6.22%。从而印证了地表径流大小直接影响土壤侵蚀强度的观点。更多还原

【Abstract】 With the deeply transform on nature by humans. The problem of soil erosion prominent gradually, and it restricts human development seriously. Soil erosion has become the most serious world’s ecological and environmental problem. We do the experiment by an artificial rainfall device with3slopes,3rainfalls,4vegetation covers as the variable factors to explore the loss of Purple Soil’s Dissolved Organic Carbon (DOC) and Dissolved Organic nitrogen (DON) in Sichuan Basin. Aimed to explore the losing of soil soluble nutrient and provide reference basis for soil erosion control. We got the following conclusions:(1)The influence by soil surface vegetation cover soluble working on DOC and DON losingThe loss of DOC and DON were reduced with the increasing of vegetation covers which in the same rainfall, the same slope conditions. Bare land soil’s DOC and DON losing are the largest. The80%vegetation cover is the smallest. It shows that plants can protect surface soil nutrients from suffering erosion well.(2) The different slope effected on DOC and DON losing.In the same vegetation cover and rainfall intensity DOC and DON increased with the slope increases. But when the slope increased from10°to20°, DOC and DON losing increased were not significantly obvious. It showed that the slope was not the main factors affecting the soil nutrient losing when the slope was small. When the slope increased from20°to30°, DOC and DON losing both improved significantly. We got a jump slope between20°-30°which made the soil nutrient losing rate increased.(3) Different rainfalls effected on the DOC and DON losing.DOC and DON losing amount increases with the increase of rainfall intensity in the same vegetation cover and slope conditions. The rains was the main factor led to soil erosion in Southern China. This test simulated3rainfalls called light rain, moderate rain and heavy rain. The test results showed that intensity the DOC and DON losing of volume in heavy rain is significantly higher than that in moderate rain and light rain. Therefore, how to fight against soil erosion by the heavy rainy season is particularly important in our real life.(4) Different soil moisture effected on the DOC and DON losing. The soil moisture has an obvious influence on water infiltration. Infiltration ability is weaker, the easier forming surface soil run-off. The experiment result showed that high moisture content of DOC loss than low moisture content increased by5.75%, DON turnover increased by6.22%through comparing the same rainfall intensity, slope, plant coverage. It confirmed that the run-off had a significant affects on soil erosion.更多还原