Invasive species comprise one of the most important yet subtle threats to biological diversity and bioresources in the Eastern and Western Himalayas. Against the overarching negative effects of invasive plant species, the global agenda has been to prevent and contain them and thereby mitigate their impacts on local bioresources, ecosystem function and human health.

The invasive alien plant species were found to spread along a wide range of altitudes in the districts of Darjeeling and Kalimpong Himalaya. Darjeeling and Kalimpong districts are the two northernmost districts of West Bengal with unique environmental eco-perception. The relief varies from 100 mts above sea level to the mighty Kanchenjunga. The area is bounded by the Sikkim Himalaya in the north, the Bhutan Himalaya in the east and Nepal Himalaya in the west. The majority of the total population is engaged in agriculture and allied sectors. The majority are marginal and small farmers cultivating crops like paddy, maize, millet and pulses, and also seasonal vegetables like cabbage, cauliflower and beans. Besides farming, animal husbandry forms a major part of their livelihood. Different invasive alien plant species were found to be colonising the habitat at different climatic conditions. Some species like Lantana camara, Ageratum conyzoides and Eupatorium adenophorum have high allelopathic potential and are harmful to the natural plant ecosystem.

Eupatorium adenophorum, which is locally known as ‘Banmara’ (forest killer), prevents forest regeneration and hampers attempts of afforestation with its fast-growing dense bushy stands. The worst invaders among these alien species include Lantana camara, Mikania micrantha, Chromolaena odorata, Eupatorium adenophorum and Ageratum conyzoides, to name a few. The alien species are rapidly growing, and they have been dominating the resident species of the region. The species are either human-introduced or natural invasions through different sources. To reduce the impact of invasive plant species on native environment and convert these into value-added products that could contribute towards local livelihoods and developing invasive species-based products in the Himalayan region.