An ecological assessment process based on integrated remote sensing model: A case from Kaikukang-Walagan District, Greater Khingan Range, China

As the impacts of global climate change, rapid economic development, and anthropogenic activities on the environment are intensifying, it is becoming increasingly apparent that we need to understand ecological conditions and their responses to climate change and human disturbances. The objective of this study was to present an ecological assessment of the Kaikukang-Walagan District using the remotely sensed ecological index (RSEI) and the newly introduced integrated ecological environment index (IEEI). This assessment will reveal the ecological responses to disturbances, and place-specific emphasis on ecological conservation. Various data such as Landsat images, advanced spaceborne thermal emission and reflection radiometer global digital elevation model (ASTER GDEM), moderate-resolution imaging spectroradiometer (MODIS) water vapor products, meteorological records, soil thickness, and soil N content data were collected and sampled. First, land surface temperature (LST), normalized difference vegetation index (NDVI), brightness, and wetness were obtained. Second, the RSEI was determined using LST, NDVI, brightness, and wetness via principal component analysis (PCA). Subsequently, IEEI was derived from the band operation between the standardized RSEI (RSEIS) and slope, soil thickness, and soil N content data. The results show that the mean RSEIS for 2000, 2002, 2007, 2011, and 2017 ranged from 0.26 to 0.48, and the coefficient of variation was 0.22. The number of areas with very good or excellent ecological conditions increased between 2000 and 2002, then fluctuated between 2002 and 2011, and reached a peak in 2017. The influence of climate change in the study area was not evident. The standardized IEEI (IEEIS) revealed that most of the study areas possessed excellent or very good ecological conditions; areas with good or fair ecological conditions were primarily located and bare land surrounded by vegetation, and areas with poor ecological conditions were primarily distributed in the urban areas of Walagan and Xiufeng. It was also shown that the IEEI is suitable for a comprehensive ecological assessment incorporating multiple ecological factors.