Tracking forest loss and fragmentation between 1930 and 2020 in Asian elephant (Elephas maximus) range in Nepal

Ashok Kumar Ram,Naresh Subedi,Dipanjan Naha,Lakshminarayanan Natarajan,Samrat Mondol,Babu Ram Lamichhane,Bivash Pandav,C Sudhakar Reddy,Nabin Kumar Yadav,Pem Narayan Kandel

doi:10.1038/s41598-021-98327-8

Abstract

Forest cover is the primary determinant of elephant distribution, thus, understanding forest loss and fragmentation is crucial for elephant conservation. We assessed deforestation and patterns of forest fragmentation between 1930 and 2020 in Chure Terai Madhesh Lanscape (CTML) which covers the entire elephant range in Nepal. Forest cover maps and fragmentation matrices were generated using multi-source data (Topographic maps and Landsat satellite images of 1930, 1975, 2000, and 2020) and spatiotemporal change was quantified. At present, 19,069 km2 forest cover in CTML is available as the elephant habitat in Nepal. Overall, 21.5% of elephant habitat was lost between 1930 and 2020, with a larger (12.3%) forest cover loss between 1930 and 1975. Area of the large forests (Core 3) has decreased by 43.08% whereas smaller patches (Core 2, Core 1, edge and patch forests) has increased multifold between 1930 and 2020. The continued habitat loss and fragmentation probably fragmented elephant populations during the last century and made them insular with long-term ramifications for elephant conservation and human-elephant conflict. Given the substantial loss in forest cover and high levels of fragmentation, improving the resilience of elephant populations in Nepal would urgently require habitat and corridor restoration to enable the movement of elephants.

Highlights

Deforestation and conversion of natural areas into human use impacts the earth’s ecosystems and functions, and threatens b iodiversity[1, 2]
The increase in human population and expansion of agriculture had led to habitat loss and fragmentation, resulting in a significant decline in elephant populations across Asia and Africa[22,23,24]
Our study provides comprehensive information on forest cover change and fragmentation within the primary elephant habitat in Nepal between 1930 and 2020

Summary

Introduction

Deforestation and conversion of natural areas into human use impacts the earth’s ecosystems and functions, and threatens b iodiversity[1, 2]. The increase in human population and expansion of agriculture had led to habitat loss and fragmentation, resulting in a significant decline in elephant populations across Asia and Africa[22,23,24]. Elephants use large areas to meet their dietary and reproductive r equirements[25, 26] Their home range size varies according to the forage. Expanding human settlements and agriculture areas has reduced connectivity, caused the loss of habitats, and a rise in human impacts on elephants, resulting in frequent conflict ranging from crop damage to human casualty and persecution of elephants[21, 30].

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Conclusion