【作者】 沈彦；

【导师】 张克斌；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2008， 硕士

【摘要】 草地沙质荒漠化是人类目前面临的重大环境与社会问题,也是我国北方干旱半干旱区草地资源利用与经济可持续发展的主要制约因素。为切实掌握草地沙化成因、发生机制、生态过程以及沙化草地植被恢复措施,本研究以宁夏沙化草地为研究对象,以现代恢复生态学理论为指导,采用野外调查和室内分析相结合的手段,对其植被物种组成、群落结构特征、物种多样性、植被恢复效应及植被遥感监测等进行了全面研究,得到如下结论:(1)盐池县2003年植被生长状况是近年来最好的一年,2005、2006年相对较差。由于全县禁牧政策的顺利实施,区域植被群落逐渐朝正向演替,预计未来5-10年,盐池县将形成以黑沙蒿、老瓜头及苦豆子为主的草原带沙地植被。近5年来盐池植被动态变化特征和5种不同土地类型群落组成结构研究表明,封育措施是沙化草地最有效、最经济的植被恢复措施之一,尤其在退耕还草和天然草地,封育对这2种土地类型的植被恢复与保护是行之有效的。(2)3个不同封育年限中植被的生活型绝大部分为草本植物,其中老封育区以多年生为主,一年生的植物还占有很大比例,饲用价值较高的优良牧草,随着封育的时间增加而减少。对沙化草地实施围栏封育不同年限后,3个不同封育年限的植被盖度、平均高度、地上生物量差异不显著。沙化草地围封4年后,进行适当割草或放牧利用,这样一方面可以使结皮松动,有利于有限的降水被植物充分利用,草地的植被尽快恢复;另一方面可抑制优势种的扩展,使伴生种、特化种获得生存空间,从而增加物种多样性和植物特征值,使生产力得到提升。(3)基于NDVI植被动态遥感监测表明,2001—2004年,盐池县植被状况明显好转,全县成片荒漠化土地逐渐减少,植被覆盖度都朝好的方向转变。中盖度植被是盐池县的主要沙化土地类型,该类型面积大,生态结构简单、脆弱,易受外界干扰而发生改变,在研究时段内变化幅度不大,是未来盐池县荒漠化治理的重点区域,同时要注意对中高覆盖度植被、高覆盖度植被地区的保护。更多还原

【Abstract】 The desertification of grassland is a serious problem of environment and society, which is also the main reason of restriction for grassland resource utilizing and sustainable development of economy in the drought and semi-drought region in north of China. It is purposed to look into the causes, the mechanisms and the ecological processes of grassland desertification and the measures of restoration, for discussing the desertification grassland in Yanchi of Ningxia. A survey for the species composition of vegetation, community structure, species diversity, the ecological process of vegetation restoration and the remote sensing of monitoring grassland vegetation under the direction of theory of restoration ecology, method of field investigation and laboratory analysis. Results are as following:(1)In 2003, the vegetation situation is the best year in recent years of Yanchi county. Because of the smooth implementation of the ban in all over the county, regional vegetation communities gradually towards positive succession, anticipated in the next 5-10 years, the A.ordosica、Cynanchum komarovii and Sophora alopecuroides will be have main position in sandy grassland vegetation of Yanchi. Over the past 5 years, the vegetation dynamics of land and 5 different types of community composition of the study show that exclusive measures grassland desertification is one of the most effective and economic restoration of vegetation. Especially in returning farmland to pasture and natural grassland, fenced way is effective management in this aspect of vegetation restoration and protection application.(2)The life of vegetation in three different closing years most are herbaceous plant, old fencing areas to perennial mainly, but also one-year-old plants account for a large proportion. After 3 different closing years, the vegetation cover, average height and aboveground biomass are not has significant difference. Desertification grassland enclosed 4 years later, proper mowing or grazing use, on the one hand can make such soil skinning loose, the water was limited to make full use of plants, the lawn vegetation resume as soon as possible; on the other hand can inhibit the expansion of the dominant species so that the associated species, access to special kind of living space, thereby increasing plant species diversity and value characteristics, productivity enhancement.(3)Basing on NDVI and the remote sensing of monitoring grassland vegetation, the vegetation state have been improvement in Yanchi county from the year 2001 to 2004. The medium vegetation fraction is the main types of vegetation fraction in Yanchi. Its area is large; its ecological structure is very fragile and it is the stress area of desertification prevention and cure in the future. At the same time, it is important to improve the protection of the vegetation of medium-high coverage and high coverage.更多还原