黄土高原植被覆盖时空变化的遥感监测及其驱动力分析

发布时间：2018-04-18 07:36

本文选题：黄土高原 + 植被覆盖变化　；参考：《中国科学院大学(中国科学院遥感与数字地球研究所)》2017年硕士论文

【摘要】：植被是一个地区承载水系、连接土壤、沟通大气的关键节点,植被覆盖度的高低往往直接关乎地表生态系统的健康与否,是评价一个地区生态环境健康的重要指标。黄土高原生态环境脆弱、植被覆盖稀疏、人类活动频繁、水土流失严重,气候变化和人类活动导致该区域植被覆盖及生态环境面临严重挑战,为了探究其植被覆盖时空变化以及背后驱动力,本文以MODIS卫星遥感数据为基础,获取2000-2015年植被覆盖度分布特征,并以此结果分析不同空间范围和不同研究时期植被覆盖度时空变化特征。结合相应时相的气象和社会经济数据分析植被覆盖与气候因素(气温、降水)以及人类活动(人口、GDP、退耕还林政策、城市化进程)之间的关系。论文主要结论如下:(1)黄土高原地区植被覆盖在空间上呈现明显的地带差异,植被覆盖由东南向西北依次递减,NDVI年平均值在0.48-0.58之间,整个研究区域多年平均值为0.53。在2000-2015年的15年期间,黄土高原植被覆盖整体处于修复状态,其NDVI值升高了约0.08。(2)黄土高原地区温度东南高、西北低,年平均气温为9.6摄氏度。降水的分布特征则表现为由东南向西北、由山地向平地递减,年平均降水448.3毫米。气温与降水对植被覆盖的影响在不同区域呈现不同相关性,与气温呈正相关区域占总的研究区域面积的62.35%,显著正相关区域(P0.05)占26.22%,两者相关系数为0.476,处于显著水平;而降水量与植被覆盖呈显著正相关区域占31.15%,两者相关系数为0.834,处于极显著水平。同一年内1-4月、10-12月,温度对植被覆盖的影响占主导作用,而在5-9月,降水量则起主要作用。(3)植被覆盖度随着人口密度和GDP的增加而逐渐降低,人口密度和GDP越高时,NDVI均值越低;同时,相对人口密度较小、GDP较低区域而言,在人口越密集、GDP越高的区域人口密度、GDP每升高一个等级,该区域NDVI均值下降的越快。退耕还林使得植被覆盖度有了明显的提升,退耕还林后年均NDVI增加了0.065。城市化进程—以西安市为例,会导致大量的耕地、绿色生态用地转化为建设用地,因此该区域植被覆盖度明显下降。(4)1999年开始的大规模退耕还林政策对黄土高原植被覆盖变化的贡献率为48.793%,其次降水量的贡献率为26.602%,气温与降水类似,都对整个研究区的植被覆盖产生影响,排在第三,前三部分的总贡献率达到85.849%;其他在局部范围对植被覆盖产生影响的驱动力因子贡献率较小,仅占14.151%,而它们之间的排序为:人口城市化GDP。
[Abstract]:Vegetation is a key node to carry water system, connect soil and communicate atmosphere in a region. Vegetation coverage is often directly related to the health of surface ecosystem, and is an important index to evaluate the health of ecological environment in a region.The ecological environment of the Loess Plateau is fragile, the vegetation cover is sparse, the human activity is frequent, the soil erosion is serious, the climate change and the human activity cause the vegetation cover and the ecological environment in this region to face the serious challenge.In order to study the spatial and temporal variation of vegetation cover and the driving force behind it, the distribution characteristics of vegetation coverage from 2000 to 2015 are obtained based on MODIS satellite remote sensing data.The spatial and temporal variation characteristics of vegetation coverage in different spatial ranges and different study periods were analyzed.The relationship between vegetation cover and climatic factors (temperature, precipitation) and human activities (population GDPP, policy of returning cropland to forest, urbanization process) was analyzed by using the corresponding meteorological and socio-economic data.The main conclusions are as follows: (1) the vegetation cover in the Loess Plateau is different in space, the annual average value of NDVI is 0.48-0.58 from southeast to northwest, and the annual average of vegetation cover is 0.53 in the whole study area.During the 15 years from 2000 to 2015, the vegetation cover of the Loess Plateau was in a state of restoration, and its NDVI value increased about 0.08. 2) the temperature was high in the southeast and low in the northwest of the Loess Plateau. The annual average temperature was 9.6 degrees Celsius.The distribution characteristics of precipitation are from southeast to northwest, from mountain to flat land, and the annual average precipitation is 448.3 mm.The effect of air temperature and precipitation on vegetation cover was different in different regions. The positive correlation area was 62.35, and the significant positive correlation area was 26.22. The correlation coefficient was 0.476, which was at the significant level.The area with significant positive correlation between precipitation and vegetation cover was 31.15, and the correlation coefficient between them was 0.834, which was very significant.From October to December in the same year, the effect of temperature on vegetation cover was dominant, while in May and September, precipitation played a major role.) the vegetation coverage decreased with the increase of population density and GDP. The higher the population density and GDP, the lower the mean value of GDP.At the same time, the higher the population density and the higher the population density, the faster the average NDVI decrease in the region where the population density is lower than that of the lower population density.The conversion of cropland to forest resulted in a significant increase in vegetation coverage, with an average annual NDVI increase of 0.065 per year after returning cropland to forest.Urbanization process-take Xi'an as an example, will lead to a large amount of cultivated land, green ecological land into construction land,Therefore, the policy of returning cropland to forest, which began in 1999, contributed 48.7933to the change of vegetation cover on the Loess Plateau, followed by the contribution rate of precipitation was 26.602, and the temperature and precipitation were similar.In the third place, the total contribution rate of the first three parts reached 85.849 percent, while the other driving force factors contributing to the vegetation cover in the local area were relatively small.Only 14.151%, and the order between them is: population urbanization GDP.
【学位授予单位】：中国科学院大学(中国科学院遥感与数字地球研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948;TP79

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