The researchers used MODIS data to monitor the vegetation in North Korea's highland areas for 9 years. They found that the vegetation growth period lasted from May to September, with peak growth in July. The start and end of the growth period varied each year, with 2003 having the shortest growth period and 2000 and 2005 the longest. Compared to South Korea's mountains, North Korea's vegetation had a longer growth period and started earlier. This study provides valuable information for creating a forest vegetation map and planning for North Korea's natural environment in preparation for reunification.