【作者】 赵彩霞；

【导师】 郑大玮；

【作者基本信息】 中国农业大学 ， 生态学， 2004， 博士

【摘要】 阴山北麓农牧交错带已成为北京及周边地区沙尘源的主要来源地之一，恢复该地区生态环境具有重要的理论与实践意义。本文以内蒙古武川县为例，采用GPS定位的方法，对不同土地利用类型下植被覆盖度、土壤等指标进行了动态观测，并在中科院兰州寒旱所进行了风洞实验。同时，结合前人的研究基础，构建了土壤风蚀量与植被覆盖率、风蚀气候因子指数与时间之间的定量关系式，从而从动态的观点比较和分析了不同类型的植被防治风蚀的性能及风蚀量与覆盖度的动态关系，这在国内外尚未见到相关报道。在此基础上，提出了适合于该地区的防治风蚀沙化的主要恢复对策与关键技术。主要结论如下： ◆ 该地区具有发生风蚀的潜在气候与土壤条件。风蚀气候侵蚀力与植被覆盖率及土壤含水量等的变化在时间上的不同步性是该地区风蚀危害严重的主要原因。 ◆ 不同类型植物覆盖度在时间上的变异是相当大的。其中作物与一年生牧草为季节性覆盖，覆盖度的月动态变化表现为作物＞一年生牧草；灌木、多年生牧草与林木则全年覆盖着地面，覆盖度的月动态变化表现为灌木＞多年生牧草＞林木。 ◆ 不同类型植被覆盖下土壤潜在风蚀量动态变化存在着显著差异，表现为灌木＜多年生牧草＜林木＜作物＜一年生牧草。也就是说，不同类型植被防治风蚀的性能的动态变化为灌木＞多年生牧草＞林木＞作物＞一年生牧草。 ◆ 潜在风蚀量与覆盖度呈“反相位”的动态变化表明，增加地面覆盖率，尤其是风蚀季节地面覆盖率是防治风蚀的最直接、最根本的措施。 ◆ 风洞试验结果表明，土壤风蚀速率随风速的增大而增大，18m／s风速是风蚀强度急剧增加的一个转折点：土壤含水量越高，土壤风蚀临界启动风速越大，风蚀率越小。6％含水量水平是风蚀强度由强变弱的一个转折点。 ◆ 不同土地利用类型防治风蚀的作用是不同的。其中灌木地是最不易蚀的，其次是天然草地；农田最易于发生风蚀危害，但退耕后种灌种草有利于防治风蚀，如若弃耕，经过多年的自然恢复最终也能起到防治风蚀的作用；农田防护林地不仅能够起到防治风蚀作用，而且能够通过降低风速而将上空的细土粒沉降下来，增加土层的厚度；但丘陵林地则不同，由于不能正常生长而减弱了其防治风蚀的作用。所以，该地区的退耕应以还灌草为主。 ◆ 退化生态系统在恢复过程中首先要遵循生态学原理。土地利用类型不同，采取的主要恢复对策与关键技术也不同，具体要因地因时而异。更多还原

【Abstract】 Dryland farming is one of the most important fields of agricultural research on which China has concentrated in recent years. Wind erosion is considered one of the more serious disasters in developing countries. The agro-pastoral ecotone in the north foot of Yinshan Mountain has been a main dust source of sandstorm in Northern China. It has been an urgent need to control and resist soil wind erosion as well as restoring ecological environment in this area. The study was carried out at Wuchuan County of the Inner Mongolia Autonomous Region, which lies in the North of China. Wuchuan County belongs to the semiarid to arid climatic zone. Wind erosion is determined by the interaction between erosive factors and factors of erodibility. Therefore, in studying patterns of soil erosion and in preventing and combating it, the relationship between the climatic conditions and factors of erodibility in their effects on wind erosion must be studied first. Subsequently one has to consider those factors that people can influence and utilize their mitigation to minimize the wind erosion. Some primary factors influencing soil wind erosion were qualitatively and quantitatively studied through meteorological data analysis, wild experiment and wind tunnel simulation test. This paper develops a simple index to show the importance of temporal variation in vegetation cover and to guide planting policies for wind erosion reduction. The main results of this thesis can be showed as blow: The region has potential wind erosion risk in the meteorological and soil factors. The main reason for serious wind erosion in this region is the nonidentity of the dynamic of wind erosion climatic factor, ratio of vegetation cover and soil water content in time. The differences of the various plant types covering a ground are very large in time. The time of crop and annual pasture covering ground are shortest and changed acutely with the time. Theirs monthly dynamic cover shows crop higher than manual pasture. While the shrub, perennial pasture and woodland in hill having covered the ground all the time, and theirs monthly dynamic cover behave shrub>perennial pasture>woodland in hill >crop>annual pasture. The respective amounts of monthly wind erosion for different plant types were also calculated. Amounts of wind erosion show annual pasture>crop>forest>perennial pasture> shrub. That is to say, shrub is the most effective in combating wind erosion, and crops without leaving stubble in winter and annual pasture are least effective. A simple index combining a wind erosive factor and a soil cohering factor allows quantification of expected erosion, a forecasting of the wind erosion hazard under the conditions of Wuchuan County, Inner Mongolia, that can be extended to other parts of the region. Because ground cover with much surface contact is absolutely necessary to reduce wind erosion, it is strongly recommended to plant perennial grasses with bush/shrubs above planting forests/woodland, annual pasture and crops that are totally harvested, in thatsequence. The results of wind tunnel simulation experiment show that wind erosion rate increased with the increasing of wind velocity. The wind speed of 18m/s is the turning point to aggravate the wind erosion. The higher of soil water content the wind erosion rate is the lighter. The’ content of soil moisture equal 6% is turning point from severity to light for the rate of wind erosion. The effects of controlling and resisting wind erosion are different in different land utilizing types. The ability of controlling and resisting wind erosion shows shrub>natural grassland>farmland, and farmland protective plantation>woodland in hill. Returning farmland to shrub and perennial pasture also benefit to controlling and resisting wind erosion. Therefore it is should be given priority to return shrub and pasture in the region. Ecological theory is the first-line in restoring degraded ecosystem. It is different in different land utilizing typ更多还原