Tropical dry woodland loss in India since 1880 and its relation to current megafauna distributions

Abstract

Tropical dry woodlands provide ecosystem services to hundreds of millions of people and support high biodiversity. Despite their importance, many dry woodlands are under high and rising human pressure, including in India, where they provide essential habitat for iconic megafauna. However, there are notable gaps in our understanding of long-term changes in dry woodlands and how they relate to the present-day distribution of megafauna. Here, we reconstructed tropical dry woodland change since the 19th century, identified archetypes of change, and explored their relationship with current megafauna distributions. More specifically, we compared the reliability of existing satellite-based woodland maps and integrated them into an ensemble map of contemporary dry woodland cover in India. This allowed us to derive recent changes in dry woodlands since 1995 and, by integrating them with historical maps, long-term changes since 1880. Finally, we used non-parametric spatial clustering to detect typical patterns of long-term woodland change and compared these to the current distribution of 14 megafauna species. These analyses yielded four major insights. First, we show a massive historical loss of dry woodland cover in India since the 19th century, with over 22 Mha (equaling 65% of dry woodlands) lost, underscoring the threatened nature of these ecosystems. Second, we identified six archetypes of woodland change, three characterized by different levels of continuous woodland decline and three showing a forest transition pattern of historical decline, stability, and subsequent recovery. This highlights the regional variations in woodland dynamics across India's dry woodlands. Third, we found a strong and positive link between current megafauna distribution and high woodland cover, especially for threatened species (r = 0.43, p < 0.05), regardless of woodland histories, pointing to the importance of maintaining larger tracts of dry woodlands for safeguarding megafauna and for megafauna restoration potential where woodlands are recovering. Finally, we show that Indian dry woodlands are still undergoing widespread losses of 6.5 Mha since 1995, and pressure on them has been increasing recently. Therefore, better protection and monitoring of dry woodlands is urgently needed, and our analyses can provide a basis for context-specific land-use and conservation planning.