Xiao Qiang, Tao Jianping, Xiao Yang, Qian Feng
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing Key Laboratory of Plant Ecology, and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, 400715, China.
Chongqing College of Arts and Sciences, Chongqing, 402160, China.
Environ Monit Assess. 2017 Sep 8;189(10):493. doi: 10.1007/s10661-017-6210-1.
In this study, we applied asymmetric Gaussian function fitting to reconstruct a high-quality MODIS normalized difference vegetation index (NDVI) time series dataset. Following this, we retrieved vegetation cover data from the Chongqing area between 2001 and 2010 using this dataset, applying a dimidiate pixel method. We then used several analytical indices to analyze spatial and temporal changes and trends related to these changes. We determined that a reconstruction of the MODIS NDVI dataset using asymmetric Gaussian fitting in conjunction with a data quality weight coefficient improved data quality and created a foundation for accurate estimations of vegetation cover. We also determined that vegetation cover in the Chongqing area decreased gradually from east to west. During the 10-year study period, vegetation cover in the Chongqing area generally increased, changing from low to high coverage. This increase in vegetation cover was mainly the result of ecological protection policies and improving climate conditions. We also found that changes in vegetation cover were mainly the result of urban construction and afforestation initiatives, but vegetation cover improved overall.
在本研究中,我们应用非对称高斯函数拟合来重建高质量的中分辨率成像光谱仪(MODIS)归一化植被指数(NDVI)时间序列数据集。在此之后,我们使用该数据集,采用二分像元法,获取了2001年至2010年重庆地区的植被覆盖数据。然后,我们使用了几个分析指标来分析与这些变化相关的空间和时间变化及趋势。我们确定,结合数据质量权重系数使用非对称高斯拟合重建MODIS NDVI数据集可提高数据质量,并为准确估算植被覆盖奠定基础。我们还确定,重庆地区的植被覆盖从东向西逐渐减少。在为期10年的研究期内,重庆地区的植被覆盖总体上有所增加,从低覆盖度变为高覆盖度。植被覆盖的这种增加主要是生态保护政策和气候条件改善的结果。我们还发现,植被覆盖的变化主要是城市建设和造林举措的结果,但总体上植被覆盖有所改善。