阴山北麓草原生态功能区植被覆盖度遥感动态监测

摘要

In order to reveal the spatial-temporal dynamic changes of fractional vegetation cover and the correlation between the temporal dynamics of vegetation coverage and the climate,the eco-function area of the grassland on the northern foot of the Yinshan Mountains was selected as the research area.The area was classified as a wind-break and sand-fixation area in the National Planning of Main Function Areas issued by the State Council in 2011.The MODIS long time series vegetation index was taken as the data source.The spatial and temporal changes of the fractional vegetation coverage and the correlation coefficient between the fractional vegetation coverage and the precipitation and temperature were analyzed by using the dimidiate pixel model,linear regression method and correlation analysis method.The results showed that the vegetation coverage condition of the eco-function area of the grassland on the northern foot of the Yinshan Mountains was poor.The fractional vegetation coverage of Chahar Right Middle Banner was the highest,ranging from 30％ to 60％,while that of Urad Rear Banner was the lowest,ranging from 2.31％ to 8.89％.The overall fractional vegetation cover showed a fluctuant decrease from 2000 to 2010.The fractional vegetation coverage of the eco-function area was dominated by low-grade (0 ～20％) vegetation and lower-grade (20％ ～40％) vegetation,which accounted for more than 90％ of the total vegetation area.High-grade (60％ ～ 80％) vegetation and higher-grade (80％ ～ 100％) vegetation just accounted for 0.62％.Moreover,during the research period,the trend of conversion from high-grade to low-grade vegetation coverage was obvious.The area of degraded vegetation accounted for 53.4％ of the eco-function area,while the area of improved vegetation accounted for just 1.63％;basically unchanged area accounted for 44.97％.According to statistical correlation analysis,the results showed that the correlation between the fractional vegetation coverage and the precipitation of the corresponding period was favorable,showing a positive correlation in most parts of the area.However,the correlation between the fractional vegetation coverage and the temperature of the corresponding period was not obvious,showing a negative correlation in most parts of the area.These indicated that precipitation was the major natural factor that affected the changes of the fractional vegetation cover in the eco-function area of the grassland on the northern foot of the Yinshan Mountains.%为揭示植被覆盖度时空动态变化及其与气候因子的相关关系,以2011年国务院印发的《国家主体功能区规划》中划定的防风固沙类型的阴山北麓草原生态功能区为研究区域,以MODIS长时间序列的植被指数产品为数据源,采用像元二分法、一元线性趋势法以及相关分析法等,对阴山北麓草原生态功能区植被覆盖时空变化及其与气温和降水的关系进行分析.结果表明:阴山北麓草原生态功能区植被覆盖较差,其中以察哈尔右翼中旗的植被覆盖度为最高,数值在30％ ～ 60％之间;乌拉特后旗植被覆盖度为最低,处于2.31％ ～8.89％之间.2000-2010年研究区植被覆盖整体呈波动下降趋势,以低等级(0 ～20％)和较低等级(20％～40％)为主,两等级面积占90％以上;处于高等级(60％ ～ 80％)和较高等级(80％～100％)水平的区域面积总和仅占研究区总面积的0.62％.2000-2010年植被覆盖度由高等级向低等级的转化趋势明显,植被退化面积占研究区总面积的53.4％,植被改善面积仅占1.63％,基本不变的区域占44.97％.相关分析显示,研究区植被覆盖度与同期降水响应关系良好,大部分区域二者呈正相关;植被覆盖度与同期气温关系不明显,大部分区域二者呈负相关,说明降水是影响阴山北麓草原生态功能区植被覆盖度变化的主要自然因素.