Vegetation dynamics and ecosystem service values changes at national and provincial scales in Nepal from 2000 to 2017

摘要

Identification of vegetation changes and economic valuation of natural resources are important to strengthen national economy and sustainable environment development. This study identified the changes in vegetation and ecosystem service values at the national and provincial scales in Nepal from 2000 to 2017. Mann Kendall test statistics and Sen's slope were computed for temporal and spatial normalized difference vegetation index (NDVI) values in each pixel having a spatial resolution of 250m and at 16-days interval. Land cover types were defined based on the NDVI values and applied ecosystem service values (ESV) coefficient. Results show that NDVI has significantly increased in Nepal with an average trend of 0.0018 yr~(?1) during 2000–2017. Except for Province 6, the NDVI has increased significantly in all the provinces. Results additionally suggested a 27.88% greening in Nepal. At the provincial scale, the highest (56.41%) and lowest (12.52%) greening were observed in Provinces 2 and 6, respectively. In 2017, the total ESV in Nepal was 21.88 billion USD which showed a 1.15 billion USD higher than in year 2000. The ESV has increased in forests but decreased in the croplands, grasslands and barren lands between 2000 and 2017. The ESV of national forest are estimated at 19.17 billion USD in 2017. The highest value of 4.17 billion USD and the lowest of 1.09 billion USD were found in Provinces 1 and 2, respectively. Meanwhile, the available ESV per capita was relatively higher in Province 6 and lower in the Province 2. As the ESV is important lifeline for the society, this study provides crucial information about how this important environmental parameter has changed over time in Nepal.