Monitoring land use/land cover change and high-altitude vegetation trends along with their climatic controls across the Central and Eastern Himalayas

Parida, Bikash Ranjan, Sparsha, Shaily, Bar, Somnath, Pandey, Arvind Chandra and Kumar, Navneet (2022) Monitoring land use/land cover change and high-altitude vegetation trends along with their climatic controls across the Central and Eastern Himalayas. In, Handbook of Himalayan Ecosystems and Sustainability, Volume 1: Spatio-Temporal Monitoring of Forests and Climate. CRC Press, pp. 225-243. (doi:10.1201/9781003268383-15).

Abstract

Monitoring the spatial pattern of vegetation growth trends is important in the Central and Eastern Himalayas as many ecosystems in the Himalayas are sensitive to climatic change. The human-induced land use/land cover (LULC) changes are the potential driving forces for changes in ecosystems. This study employed MODIS (MCD12Q1) product to quantify the spatial pattern of LULC from 2001 to 2019. The long-term vegetation datasets (NDVI3g) (1982-2015) were utilized to estimate vegetation trends and climatic variables (e.g., precipitation, soil moisture, temperature, solar radiation) trends. The Mann-Kendall (τ) test and Theil-Sen’s slope were deployed for computing trends over vegetation (e.g., forests, shrublands, savannas, croplands, and grassland). The results showed a prominent large-scale greening trend of croplands (77% of area) and forests including shrublands, savannas, and grassland (42% of area), mostly across the Central (Nepal) Himalayas. The browning trends of forests were also evident, especially over the Eastern Himalaya (Bhutan). The greening trends of vegetation were mainly associated with climatic factors like precipitation and soil moisture, and the corresponding correlation coefficients (r) were 0.69 and 0.28, respectively at p-value ̼ 0.001. Additionally, temperature control on vegetation was found at higher elevation zones of the Central and Eastern Himalayas (r = 0.93, p-value ̼ 0.001), whereas browning trends of vegetation occurred due to temperature-induced moisture stress along with the decreasing trends of solar radiation, and a profound impact was seen over Bhutan. Human-induced land-use change (e.g., shifting cultivation, deforestation) was also attributed to declining vegetation growth since an increase in built-up area was noticed that mainly replaced the croplands and barren land over the study regions. Therefore, the quantification of vegetation trends is important for understanding and managing agriculture and forests ecosystems located in the high-altitude zone, and attention from ecologists and policymakers is required to monitor and manage vegetation in the Himalayas.

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Contributors

Author: Somnath Bar

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