~ by Archita Sharma
Two conservation priority landscapes in India - the Western Ghats and Central India remain major strongholds for several endemic and threatened species. However, urbanization and land conversion have resulted in wide-scale habitat fragmentation in both the landscapes. Fragmentation can alter how animals move across a landscape.
Wide-ranging mammals are particularly affected because they travel long distances to forage, breed, and find new territories. Identifying where and how have the mammalian movements been impacted at large regional scales will be critical in ensuring habitat connectivity and preventing local extinctions.
A new study published in Biological Conservation evaluated landscape-wide permeability to the movement of five endangered and vulnerable mammals - Asian Elephant, Gaur, Leopard, Sambar, and Sloth Bear in these two priority landscapes. The expansive study area covered 120,000 km2 of the Western Ghats and 729,000 km2 of the Central Indian region. For each of the five study species, the researchers modelled movement in the presence and absence of landscape features such as land-use land-cover, infrastructure and human population. They generated spatially explicit maps identifying areas where animal movement is impeded, reduced, unrestricted, increased, and channeled. These categories can be interpreted as follows – movement is impeded and reduced due to underlying high resistance landscape features, unrestricted due to underlying low resistance areas, finally increased and channeled due to high resistance surrounding landscape features.
The findings of the study reveal reduced movement across all five focal species. Impeded dispersal or movement was directly linked to human land-use, high linear infrastructure density, and human population. Roads, power lines, railways, coupled with human modified land-use, offered high resistance to mammal movement. In contrast, natural areas supported movement, including those lying close to the human population. These natural areas included forests, scrublands, grasslands, and barren lands. Natural areas made up 50-70% of unrestricted movement in Central India and 20-55% in the Western Ghats. Since unrestricted movement areas offer the highest permeability to moving mammals, it is imperative to preserve the identified natural areas critical for movement.
Notably, the study shows that the existing tiger corridors such as Kanha- Pench and Kanha-Achanakmar in Central India, as well as Cauvery-Bannerghatta and Periyar-Shendurney in the Western Ghats, offer unrestricted and increased movement areas for all focal species. This finding adds to the conservation value of corridors for maintaining dispersal and gene flow. The persistence and movement of many wide-ranging mammals outside of Protected Areas can only happen by planning for connectivity in multi-use landscapes and conserving wildlife corridors.
India's land use policy and infrastructure planning must involve landscape ecologists in the early stages of planning. The research team highlights the need to adopt site-specific guidelines for reducing the impacts of human land-use and infrastructure on mammal movement. The permeability maps generated by the study are available online (https://indiaunderconstruction.com/) and can be highly useful in prioritizing sites in need of conservation measures in the Western Ghats and Central India. Finally, the study outlines an approach that can be extended to other conservation landscapes to assess how permeable are current landscapes for wildlife movement in India.
Original Paper: Jayadevan, A., Nayak, R., Karanth, K. K., Krishnaswamy, J., DeFries, R., Karanth, K. U., & Vaidyanathan, S. (2020). Navigating paved paradise: Evaluating landscape permeability to movement for large mammals in two conservation priority landscapes in India. Biological Conservation, 247, 108613. https://doi.org/10.1016/j.biocon.2020.108613
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