论文标题:黄河源区玛曲县草地沙化动态监测及区域景观结构分析研究
Grassland Sandification Dynamic Monitoring and Landscape Pattern Analysis of Maqu County in Source Region of Yellow River
论文作者
论文导师 王辉,论文学位 硕士,论文专业 水土保持与荒漠化防治
论文单位 甘肃农业大学,点击次数 505,论文页数 59页File Size2536K
2006-05-26论文网 http://www.lw23.com/lunwen_1525542/
Source region of the Yellow River; Grassland desertification; landscape pattern;3S technology
草地沙化是引起草地持续退化和生产力不断下降的主要原因之一。在多因素综合作用下,玛曲县近50年来天然草地沙化面积迅速扩大,沙化程度不断加剧。特殊的地理位置及独特的生态作用,该区域的草地沙化具有典型特征和重要的研究意义。本文以TM影像资料为信息源,结合GPS地面定位样方调查及历史资料、利用GIS分析手段,分析研究了玛曲县草地沙化现状及近14年来变化动态,并应用景观生态学原理与方法,对沙化区域的景观结构特征及沙化对区域景观的影响进行了分析研究,结果表明: (1)玛曲县草地沙化面积总体呈较为明显的增加态势。区域现有沙化草地面积7136.77 hm2,与1999年相比增加了1056.77hm2,总增长率为17.38%,年均增长率为4.35%。其中,流动沙地和半固定沙地是区域沙化土地面积增加的主要类型。 (2)区域沙化程度整体上属重度水平。在玛曲县现有沙化草地中流动沙地占沙化土地总面积的35.5%,半固定沙地占沙化土地总面积的12%,固定沙地占沙化土地总面积的52.5%。全县极重度和重度沙化草地面积总计占沙化面积的41.4%,中度、轻度沙化草地面积分别占31.4%和27.2%。 (3)区域沙化土地分布具有一定的规律性。玛曲县沙化土地主要分布在沿黄河两岸的阶地带和冲积河滩。其中,固定沙地、半固定沙地是沙化草地的主体,分布相对集中在冲积河滩和过渡放牧的退化草地内部;而流动沙地的分布较为分散,主要分布在黄河阶地及河湾滩地。 (4)从沙化发展动态看,玛曲县沙化范围呈逐步扩展趋势。天然草地的沙化范围总体呈现出向黄河源头和下游延伸的趋势,沙化所涉及的黄河沿岸长度已达186.12 km,占县境内黄河总长的43%。同时,沙化草地分布区已从原来主要分布的沿黄河两岸阶地、河湾滩地,扩展到部分退化草场以及南部的部分湿地边缘。 (5)区域沙化存在着较为明显的潜在发展空间。从沙化现状分析,现有沙化草地中,固定沙地和半固定沙地占比重较大,它们是转化为流动沙地的主要来源。另外,3616.07 hm2的潜在沙化地将是未来沙化土地增加的主要源区。如果不及时加以治理,潜在沙化土地将进一步退化,从而使区域沙化土地面积不断增加。 (6)从整体水平来分析,区域景观具有一定稳定性。玛曲县沙化区域景观呈现出以草地为基质,湿地、灌木林地、沙化草地、水体及居民工矿用地等6种景观要素类型镶嵌分布的总体形式。草地、湿地、河流水体及灌木林地等自然景观是景观格局的主要构成要素。居民地作为区域典型的人工景观在整个区域景观中所占比例较小,对景观结构的影响微弱。 (7)受黄河走向及阿尼玛卿山和西倾山两大山脉的地理位置和典型地形地貌的影响,玛曲县沙化区域景观格局呈明显的条带状分布特征。景观结构格局依其要素组成及
Grassland sandy desertification is one of the main reasons that the grassland ecosystem degradation and productivity decline continuously. Under many synthetical factors, the area of desertification grassland extended quickly and the degrees of desertification turn worse continuously in the last five decades in Maqu County. The special geographical position and ecological function makes the grassland desertification of this district have the typical features and important research significance. Based on the data of TM images, the historical data and investigated results through the GPS Land-based positioning, the present situation of natural grassland desertification of Maqu County was investigated and contrasted with the Monitoring result of the last 14 years. The result showed that: (1) The area of the desertification grassland increased evidently in this region. The total area of the desertification grassland in Maqu County is 7136.77hm2. Contrasted with the 1999, it had increased 1056.77hm2, the total growth rate is 17.38% and the Annual mean growth rate is 4.35%. Mobile dune and semi-fixed sand land are the main causes of desertification land increase. (2) The degrees of regional desertification were serious. The area of mobile dune, semi-mobile sand land and fixed sand land of the current desertification area occupies respectively 35.5%, 12% and 52.5% of total. The percentage of the severe and very severe degrees is 41.4% of the total area. The slight degrees and moderate degrees is 31.4% and 27.2%. (3) The desertification land distributions show the certain orderliness. The desertification land distribute mainly in fluvial terrace and alluvion. Fixed sand lands and semi-fixed sand lands are the main type of the desertification grassland, their distribution concentrate correspondingly in the alluvion and the overgrazing grassland, while the mobile dune intersperse on the fluvial terrace and alluvion of river bend. (4) The range of desertification extended gradually. The distribution range of desertification extends to the upper stream and lower reaches of the Yellow River, and the drainage area of desertification land reached 186.12km long, which occupies 43% of the Yellow River basin in Maqu County. The desertification grassland extends its distribution area, from the fluvial terrace and alluvion to part of the degenerate grassland and the marsh margin. (5) The development of the regional desertification shows a wide potential range. Fixed sand lands and semi-fixed sand lands have large percentage of the current desertification land types, they are the main type of mobile dune is converted. In addition,potential sand land of 3616.07hm2 is main source of desertification land in the future. If the potential sand land is
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