Forest restoration and support for sustainable ecosystems in the Gandaki Basin, Nepal.

Abstract

Restoring degraded forest is essential if we are to reduce human pressure on natural ecosystems and their biodiversity. Forests were nationalized in 1957 in Nepal and as a consequence, forest cover declined from 45% in 1964 to just 29% in 1994. However, as its response, sectoral plans and policies, particularlyintroduction of community-based forest management programs since the1980s and conservation activities resulted inlargescale forest cover restoration. Here, we examined the forest cover change in the Gandaki River Basin (GRB), thecatchment with the largest altitudinal variation (ranging from ± 93 to 8167m) and environmental and ecological significance. To see how forests have changed since then, we analyzed snapshots of spatiotemporal, ecological and physiographic changes in forest cover, and forest type at decadal intervals from 1996 to 2016 using Landsat 5 and 8 satellite images. We observed an overall gain in forest cover of 207 km2, from 7571 km2 (34.4% of the total area) in 1996 to 7778 km2 (35.3%) in 2016. Of the 21 forest cover types identified, the greatest forest coverage during 2016 was of Schima-Castanopsis forest (25.9%) and hill sal forests (16.4%). In terms of physiographic zones, land below 500m (Tarai) where most people live, witnessed gradual declines in forest cover, in contrast to large increases in forests above 500m. Historical examination of forest cover at ecological and physiographic scales helps to identify the elevation-wise distribution of forest resources, vegetation composition, ecosystem characteristics,anthropogenic pressure upon vegetation, and hence theoverall influence of LULC upon the environment. These outputs willassist planners, policy makers, and researchers in their formulation of effective basin wideplans and policies to ensure the protection of basin level biodiversity and ecosystem function.