Tropical forests are the most complex and diverse terrestrial ecosystems on earth, which are undergoing rapid fragmentation, degradation (Janzen, 1998), and deforestation posing an enormous threat to global biodiversity (Barlow et al., 2016;Hare et al., 1997). It covers only 7% of the earth's land surface with >50% of the known species that are disappearing at a rate of 0.8-2.0% year −1 (Sagar et al., 2003) with the global declining rate of 13.5 Mha of forests year −1 (Kobayashi, 2004). More than half of the forest tree species worldwide are being threatened with anthropogenic disturbances and environmental changes (ter Steege et al., 2015) of which ~7800 tree species are threatened with extinction (Oldfield et al., 1998).