Examining day forest dynamic change with times series LANDSAT images (Djibouti)

抄録

The Day forest, containing one of the only two relic forested areas of Djibouti is disappearing at an alarming rate mainly due to a combination of man-induced degradation and climatic condition. We investigate the forest cover dynamics changes in Day forest by using multi-spectral temporal satellite imagery series (from 1990 to 2016). The research was conducted by two approaches that employ different method to assess dynamics changes. First, we proceed with image differencing procedure of NDVI of different dates in order to quantify the overall vegetation change that occurred throughout time. Then, differences between the NDVI are classified as either forest gain or forest loss. Finally, we compared the resulted classified forest dynamics changes against the post classification comparison method. The results of both methods indicated a drastic decrease in the forested area Since 1990 to 2016. From 15 km² (NDVI differencing) and 28 km² (post classification) in 1990 to 204 km². (NDVI differencing) and 216 km² (post classification) in 2016. The recent climatic changes (period of drought since 1999) and the anthropogenic activities in the area are the main resean why such regression is observed.