Comparing invasiveness of native and non-native species under changing climate in North-East India: ecological niche modelling with plant types differing in biogeographic origin.

We assess the invasive potential of Ageratum conyzoides, Hevea brasiliensis, Urena lobata and Imperata cylindrica differing in habit and biogeographic origin through ecological niche modelling in the context of the 2000 and 2050 climates of North-East (NE) India. Out of these four species, Ageratum conyzoides, Urena lobata and Imperata cylindrica are naturally occurring weed species and Hevea brasiliensis is a cultivated tree species. This study tries to address a basic question whether species with similarity in biogeographic origin may have some uniform strategy to succeed in invasion process. Ecological niche models predicted that Ageratum conyzoides (a shrub) and Hevea brasiliensis (a tree) of South American origin have greater potential to invade/distribute in NE region of India by 2050 than two other species, Urena lobata and Imperata cylindrica, of South-Asian origin. The latter two species show lower potential to invade in NE India in 2050 compared with their extent of distribution in 2000. A set of major contributing bioclimatic factors responsible for distribution of two South-Asian species (Urena and Imperata sp.) remain more or less constant between 2000 and 2050 climates. However, the distribution of Ageratum sp. and Hevea sp. with respect to two climate scenarios is attributed by two different sets of major bioclimatic factors. This indicates the robustness of the species to get adapted to different set of climatic variables over time.