ASSESSING ECOLOGICAL SERVICES IN THE THREE-NORTH SHELTER FOREST AREA OF CHINA USING REMOTE SENSING

This study analyzes the change characteristics of the vegetation's net primary productivity (NPP) and calculated the economic value of ecosystem services in the TNSFP area from 2000 to 2019 using NPP, normalized vegetation index, and precipitation data. Consequently, the following observations were derived from the study's results. First, the annual average vegetation NPP of the project area range was 4.5 gC center dot m-2 center dot a-1-581.7 gC center dot m-2 center dot a-1, and the annual average vegetation NPP was 162.1 gC center dot m-2 center dot a-1; high (low) NPP were mainly concentrated in the eastern (western) part. Second, the areas where the NPP increased (decreased) significantly (p<0.05) accounted for 42.70% (0.27%) of the entire area; the areas where it did not change significantly (p>0.05) accounted for 42.78% of the total area. Third, the total ecosystem service value of the TNSFP area was 0.27x1018 dollar/a; the economic value of soil conservation, carbon fixation and oxygen release, water conservation, and nutrient circulation was 0.23x1018 dollar/a (84.20% of the total area), 0.42x1017 dollar/a (15.61%), 0.15x1010 dollar/a (0.01%), and 0.50x1015 dollar/a (0.19%), respectively. Lastly, human activities and increased precipitation are the dominant factors causing vegetation restoration. Essentially, the study's findings provide theoretical and practical references for the healthy and sustainable development of the ecological environment in the Three-North Shelterbelt Area.