Plant invasion in protected areas, the Indian Himalayan region, and the North East India: progress and prospects.
Global biodiversity is not uniformly distributed in terms of species richness. The global and national protected areas (PAs), the Indian Himalayan Region (IHR) and the North East (NE) India, are extremely rich in plant biodiversity, contributing to the environment and the socio-economy/livelihood prospects, linked with human health or well-being. However, the anthropogenic disturbances have modified the vegetation structure of PAs, IHR, and NE India, such that the pristine landscapes are now ripe for the encroachment of invasive alien plants (IAPs). The plants invasions is now increasingly being realised as a major threat to biodiversity globally and the ecologically sensitive mountain ecosystems are no exception. The abrupt spread of IAP in these regions can significantly exacerbate the biodiversity conservation problems, as these regions are already faced with challenges of habitat fragmentation and climate change. Also, the complex interactions among the plants invasion, habitat destruction and climate change can further impose a challenge to the restoration ecologists. Interestingly, the invading plants are equipped with several species or site or habitat-specific adaptive mechanisms like the presence of allelochemicals as novel weapons that facilitate their landscape spread and ecological dynamics. This review describes the theories or hypotheses which may account for the accelerated IAPs spread in IHR, NE India and PAs. The research progress in IHR and NE India is discussed with respect to worst invaders like Lantana camara, Chromolaena odorata, Ageratum conyzoides, Parthenium hysterophorus, Mikania micrantha, etc. In this respect, the outcome of preliminary research in NE India to identify the dominant invaders through quantitative methods is also mentioned. Lastly, the management strategies are described to mitigate the IAPs hazards for sustainable biodiversity conservation.