Ecological niche modeling and local knowledge predict new populations of Gymnocladus assamicus a critically endangered tree species

Abstract

Gymnocladus assamicus is a critically endangered tree species endemic to northeastern\nIndia. Local inhabitants traditionally used this species for a variety of purposes. However, rapid population\ndeclines led to the species being considered extinct, until fieldwork in 2004 to 2007 identified\n14 discrete populations of 1 to 7 trees each. To overcome constraints on field surveys imposed by the\nregion’s remoteness and rugged terrain, we targeted areas of further field inventories by estimating\nthe potential distribution of the species. Ecological niche modeling enabled us to identify 26 sites\nwhich the model predicted to be highly suitable for the species’ occurrence. We conducted rapid field\nsurveys at 14 of the most accessible of these predicted sites. New populations were discovered at 5 of\nthe 14 surveyed sites. In the remaining 12 less accessible sites, we interviewed residents from nearby\nvillages and obtained indirect evidence of populations at 5 additional sites, which remain to be confirmed\nby direct field observations. This study demonstrates the utility of niche modeling as a tool for\nlocating new populations of rare and endangered species. Our results will enhance ongoing efforts\ntowards in situ conservation of this endangered species.