【作者】 闫丽；

【导师】 包慧娟；

【作者基本信息】 内蒙古师范大学 ， 自然地理学， 2010， 硕士

【摘要】 土地沙漠化是人类面临的重大全球生态环境问题之一,造成了严重的环境恶化和经济贫困,威胁着人类社会的生存和发展。我国沙漠广布,是世界上受沙漠化危害最为严重的国家之一,沙漠化的研究对于中国具有十分重要的意义。植被变化和风沙活动是半干旱地区两种主要的地表过程,影响着沙漠化发展的方向。深入研究植被和裸沙的空间分布及其动态特征为阐明植被变化和风沙活动的相互关系提供基础,为进一步解释半干旱区地表变化的规律及其机制提供依据。基于以上的考虑,本文以半干旱地区植被变化和风沙活动明显的奈曼旗沙质草地为例,在景观生态学理论的指导下,采用遥感与地理信息系统等手段,结合野外调查,对以下内容进行研究。1.对研究区遥感影像进行分析,结合实地考察归纳总结得到奈曼旗沙质草地植被和裸沙的空间分布类型主要有如下三种:相对均匀型,梯度型,几何型。相对均匀型指植被斑块和裸沙斑块在空间分布上比较均匀,植被或裸沙地的空间分布没有明显的集中或渐变特征。梯度型主要是指从完全裸沙地到植被集中区,植被和裸沙的空间分布具有明显的梯度渐变过程,主要分布在河流和湖泊附近。几何型指具有几何形状的农田植被与裸沙地在空间上的分布形式。2.对奈曼旗沙质草地植被和裸沙空间分布进行深入研究发现:奈曼旗沙质草地植被-裸沙空间分布主要集中在连续的几个NDVI值之间,不同分布类型峰值的大小和半峰宽各不同。植被破碎化主要发生在两个NDVI区段内。在斑块破碎化过程中植被为基质,裸沙斑块状分布与高植被梯度型分布的斑块变形程度相似。植被和裸沙细密度均匀分布类型中斑块变形高于其他类型。低植被梯度分布型中斑块的变形不明显。3.对同一NDVI值斑块的空间分布特征分析发现:同一NDVI值内,存在着斑块数量随着斑块面积的增加而呈幂函数减小,随斑块周长的增加而呈幂函数增加的规律,且斑块数量越多时该规律表现越明显。4.对典型样带近二十年植被-裸沙空间分布的面积曲线,斑块密度曲线,形状指数曲线的动态特征参数进行分析,发现植被-裸沙动态变化具有三种主要模式。模式一为1987年到1992年斑块面积快速集中在较窄的NDVI值之间,并快速向低NDVI移动,斑块形状快速简单化;1992年到2002年斑块面积较慢集中较窄的NDVI值之间,快速向高NDVI移动;2002年到2009年斑块面积缓慢集中较窄的NDVI值之间,缓慢向低NDVI移动,斑块形状缓慢简单化。模式二为1987年到1992年斑块面积缓慢分散在较宽的NDVI值之间,缓慢向低NDVI移动,斑块形状快速简单化;1992年到2002年斑块面积快速集中在较窄的NDVI值之间,快速右移向高NDVI移动,斑块形状缓慢简单化;2002年到2009年斑块面积较快分散在较宽的NDVI值之间,缓慢向低NDVI移动,斑块形状缓慢简单化。模式三为1987年到1992年斑块面积分布基本不变,缓慢向低NDVI移动,斑块形状快速简单化;1992年到2002年斑块面积快速分散在较宽的NDVI值之间,快速向高NDVI移动,斑块形状缓慢简单化;2002年到2009年斑块面积快速集中在较窄的NDVI值之间,缓慢向高NDVI移动,斑块形状较慢复杂化。5对奈曼旗沙质草地植被-裸沙动态的驱动力分析发现:气候因素中大风、降水量和蒸发量变化与植被-裸沙空间分布动态的相关性较大;人为因素的影响不大,但与年末牲畜栅栏头数和农牧民纯收入具有一定的相关性。并对Lancaster气象模型进行了验证。更多还原

【Abstract】 Desertification is one of the major global environmental problems that human faced, It has caused serious environmental degradation and economic deprivation and even hazard the survival and development of human society. Desert widely distributed in China and it is one of the countries that damaged seriously by desertification. Therefore, desertification has great significance to China. Vegetation change and sand activity is two major surface processes in semi-arid regions, affecting desertification development. For clarifying the relationship between vegetation changes and sand activities and further explaining the variation of the surface and mechanism in Semi-arid areas, this paper studied the vegetation coverage together with spatial distribution and dynamic Characteristics of the bare sand deeply.Based on the considerations above, it takes sandy grassland in Naiman Banner, which has apparent vegetation change and drift activity, for example. This paper is under the guidance of landscape ecology, using remote sensing and geographic information systems and field investigation to research on the following contents.1. From analysis of remote sensing image in study area combine with the field investigation, it can conclude the sandy grassland vegetation and spatial distribution of the bare sand in Naiman Banner, there are three main types as follows: relatively uniform type, gradient type, geometry type. Relatively uniform type refers to vegetation patches and bare sand patches distribute uniformly in space and the dirtibution is no obvious concentration or gradient characteristics. Gradient-based mainly refers the completely bare sand move to vegetation clusters areas. The distribution of vegetation and bare sand has obvious gradient gradual process.It mainly distributed in the vicinity of rivers and lakes. Geometry type means with geometric shape of the field vegetation and form of the bare sand in the spatial distribution.2. From the reasearch on the vegetation coverage together with spatial distribution and dynamic characteristics of the bare sand in Naiman Banner, we found that: Sandy grassland vegetation - bare sand distribution in Naiman Banner concentrated mainly in a few NDVI values, peak size and half-peak breadths of distribution types vary from unit to unit. Vegetation - bare sand fragmentation occurred mainly in two NDVI sections. The vegetation is basis in patch fragmentation process, bare sand and patchy distribution and patch of High vegetation - bare of sand gradient type distribution similar to their deformation. Plaque deformation in vegetation and uniform density type of bare sand higher than other types. Plaque deformation in Low vegetation - bare patch of sand in the gradient distribution is not relatively significant.3. From the analysis features about the spatial distribution of same NDVI values for plaque we found that: the Area and patch number of the same NDVI values for plaque has power function relationship, index of location parameters is negative; Patch perimeter and area of the same NDVI values for plaque aslo has power function relationship, index of location parameters is Positive.4. From the analysis of area curve about vegetation - the spatial distribution of bare sand, patch density curve, the shape of the dynamic characteristic parameter exponential curve in typical sample with nearly two decades, we found that vegetation - bare sand dynamics has three main modes. Mode 1 for the 1987 to 1992 concentrated fastly between a more narrow NDVI values and took rapid movement to the low NDVI values, simplification of plate was fast. From 1992 to 2002, it focused slowly between the more narrow NDVI values and moved rapidly to high NDVI; From 1992 to 2002, it slower focused between the more narrow NDVI values and moved slowly to low NDVI values, simplification of plate was slow. Mode 2 for the 1987 to 1992 concentrated slowly between a more wide NDVI values and took slow movement to the low NDVI values, simplification of plate was fast. From 1992 to 2002, it focused fastly between the more narrow NDVI values and moved rapidly to high NDVI; simplification of plate was slow.From 2002 to 2009, it focused rapidly between the more wide NDVI values and moved slowly to low NDVI values, simplification of plate was slow. Mode 3 for the 1987 to 1992, it basically unchanged and took slow movement to the low NDVI values, simplification of plate was fast. From 1992 to 2002, it focused fastly between the more wide NDVI values and moved rapidly to high NDVI; simplification of plate was slow.From 2002 to 2009, it focused rapidly between the more narrow NDVI values and moved slowly to high NDVI values, complication of plate was slowish.5. From the analysis on driving force of Sandy grassland vegetation - bare sand dynamics in Naiman Banner, we found that climate change is the the main reason for vegetation - bare sand Changes, In particular, wind, precipitation and evaporation. Human activities on Sandy grassland vegetation - bare sand dynamics in Naiman Banner also has some impact, but not obvious.更多还原