ANALYSIS OF THE CHANGE IN VEGETATION COVERAGE OF CHALK SOIL WASTELAND DURING THE GROWING SEASON BASED ON UAV SEQUENCE IMAGE

Normalized Difference Vegetation Index (NDVI), the most widely applied vegetation index, can accurately reflect the vegetation coverage and growth on chalk soil wasteland, and provide bases for the further optimization of vegetation. In this research, a chalk soil wasteland located in Fengquan District of Xinxiang city of China was taken as the study target, and photos of the vegetation coverage of the chalk soil wasteland during the growing season (March to October) were taken with a multispectral camera carried on Dajiang unmanned aerial vehicle (UAV). The results have shown that the mean NDVI of the wasteland during the growing season is 0.21. After almost two decades of treatment, the ecological environment improves, but it just reaches medium coverage. The monthly mean NDVI of the wasteland during the growing season ranges between 0.12 and 0.30, which is of medium coverage or level below. The monthly NDVI level distribution of the wasteland during the growing season indicates that the ratio of high vegetation coverage is relatively low, and the vegetation environment of the wasteland still needs further improvement. The monthly NDVI gap of the wasteland during the growing season shows that the ratio of NDVI increasing area of most months is far greater than the NDVI decreasing area. But the decreasing area caused by the management, high temperature and draught in May and June is far greater than the increasing area. In August and September, leaves begin to fall, and the chlorophyll content decreases, so the ratio of NDVI decreasing area increases rapidly to the second peak. The species and area coverage of evergreen plants, LAI value of plants and canopy structure would influence NDVI.

Automated summary

This study used the Normalized Difference Vegetation Index (NDVI) to assess the vegetation coverage of chalk soil wasteland in Fengquan District, Xinxiang city, China. The results showed that the vegetation coverage of the wasteland was at a medium level, with the ratio of increasing NDVI area greater than the decreasing area in most months.