基于无人机和MODIS数据的巴丹吉林沙漠植被分布特征与动态变化研究

Distribution Characteristics and Dynamic Changes of Vegetation in Badain Jaran Desert: Based on UAV and MODIS Data

荒漠植被在减缓沙漠扩张、阻挡风沙入侵绿洲、维护绿洲稳定性方面具有重要意义。通过无人机搭载多光谱相机获取地面样地高分辨率NDVI数据以计算植被覆盖度,结合MODIS-NDVI数据,分析了MODIS-NDVI与无人机获取NDVI数据之间的一致性,进而建立MODIS-NDVI数据与样方植被覆盖度的空间反演模型,以研究巴丹吉林沙漠植被分布特征、动态变化及其对气温、降水的响应规律。结果表明:(1)基于无人机多光谱数据大样方植被覆盖度和MODIS-NDVI数据构建的植被覆盖度反演模型具有较高的模拟精度。(2)研究区总体植被覆盖度较低,空间上呈由东南向西北递减的趋势。(3)植被覆盖度总体呈现上升趋势,沙漠边缘的增速较沙漠内部更为明显,其中沙漠边缘增长率达1.53%/10a,而沙漠内部为0.84%/10a。沙漠边缘57.12%植被出现改善,而沙漠内部植被改善的面积约为21.26%。(4)植被生长主要受制于生长季降水量并呈现出明显的季节变化,此外植被对降水和气温的响应存在一定的滞后效应。

The desert vegetation is of great significance in restraining the desert expansion,preventing the sandstorm invasion and protecting the oasis stability.In this paper,we obtained the high resolution NDVI data by the multispectral camera on a UAV(Unmanned aerial vehicles)to calculate the vegetation coverage at sample area,and the vegetation NDVI data was extracted from the MODIS data.We analyzed the consistency between MODIS-NDVI and UAV-NDVI and constructed the spatial inversion model by combining the MODIS-NDVI data and the vegetation coverage,to study the distribution characteristics,the dynamic change of vegetation,and its response to the temperature and precipitation in Badain Jaran Desert and its marginal region.The results show that:(1)The inversion model in combination with the MODIS-NDVI data and the vegetation coverage based on multi-spectral data had high simulation accuracy.(2)As a whole,the vegetation coverage was relatively low,and the spatial pattern was gradually decreasing from southeast to northwest.(3)The annual average of vegetation coverage showed an upward trend,and the growth rate of the desert edge was more obvious than that of the desert interior,in which the growth rate was 1.53%per ten years in desert marginal regions while 0.84%per ten years in the desert interior regions.Simultaneously,57.12%of the vegetation improved in marginal regions,while about 21.26%meliorated in interior desert regions.(4)The vegetation showed the seasonal changes and its growth was mainly constricted by precipitation in growing seasons,furthermore,the response of vegetation to precipitation and temperature had a certain lag effect.