Regional assessment of diversity and distribution of native tree species in South Asia

Trees have evolved as vital elements of terrestrial ecosystems and provide various ecosystem services. The presence of several biodiversity hotspots highlights South Asia as a biodiversity rich with a high degree of endemism. However, little is known about the diversity of native tree species in this region. Here, we summarize the information on the diversity and distributions of native tree species in South Asia. A country-wise inventory of native tree species and their geographical occurrence was compiled across eight South Asian countries using the “Global Tree Search” and “Global Biodiversity Information Facility” database. A total of 3,172 native tree species were recorded in 138 families in the region. We found that > 50% of them belonged to 15 highly diverse families led by Rubiaceae (223 spp), Lauraceae (217 spp) and Leguminosae (164 spp). Syzygium (102 spp), Ficus (81 spp) and Diospyros (74 spp) were the top three genus with high native tree diversity. Although India topped the list with 2,613 species, however, based on the country’s per unit land area, Bhutan and Sri Lanka had high tree diversity. India and Sri Lanka were ranked high, with 651 and 382 species of endemic trees. Around 33% of Sri Lanka’s native tree diversity was found to be threatened and had a high risk of loss of biodiversity. Two Himalayan neighbours, Bhutan, and Nepal had 50% similarity in their native tree species. Overlaying land cover patterns with native tree distribution revealed that South Asian urban landscapes were mainly dominated by IUCN’s least-concern (LC) Red Listed native tree species. This study provides important baseline information on native tree species and advocates to promote the development of appropriate conservation measures for native tree species in South Asia, including their use in urban greening.