Invasive Alien Species (IAS) represent a grave threat to India's globally significant biodiversity, agricultural productivity, and public health. These are non-native organismsâÂÂencompassing plants, animals, and microbesâÂÂthat, once introduced, establish themselves and proliferate rapidly, causing devastating ecological and economic consequences. These species disrupt native plant communities, alter ecological processes, and affect sectors such as agriculture, forestry, and protected area management.A Assessment report, compiled by National Biodiversity Authority for the Ministry of Environment, Forests and Climate Change, Government of India, is crucial for framing the national management strategies, identifying species based on their known impacts (such as biodiversity loss, economic loss, and health hazards), and tracking their continued range extension across various Indian ecosystems. With globalization, climate change, and anthropogenic disturbances, the risk and spread of invasive plant species have accelerated, making monitoring and management critical for conservation.
Diversity and Distribution of Invasive Plants in India
India hosts a rich diversity of invasive alien plant species across ecosystems. An inventory documented 1059 invasive species, belonging to 587 genera and 142 families, with most species originating from South America, North America and Europe. Protected areas and forest reserves are particularly affected, with studies documenting 41 major invasive plant species across 54 protected areas. Grasslands, coastal wetlands, and tropical deciduous forests are also vulnerable to invasions. Field surveys have also identified first records of species like Hypoestes phyllostachya in North India, indicating that invasions continue to spread into new regions. To map species distribution and identify invasion hotspots, tools like MaxEnt modelling and remote sensing have been used. Another powerful tool called DNA barcoding has emerged for rapid identification of invasive plants, allowing faster and more reliable detection compared to traditional morphology based approaches.
Drivers and Mechanisms of Invasion
The spread of invasive plants is driven by climatic conditions, anthropogenic factors, and biological traits. Climate anomalies in temperature and precipitation strongly correlate with invasive species distribution. Human activities such as road constructions, fires, and habitat modification create dispersal pathways and disturbances that favor invasive plant species. Biological traits including high reproductive rates, dispersal abilities, and fungal endophyte associations contribute to successful establishment and expansion of invasive plants. Future climate scenarios predict further expansion of species such as Ageratum conyzoides, Ipomoea carnea, and Mikania micrantha, underscoring the need for predictive modelling to guide conservation planning.
Ecological Impacts
Invasive plant species have profound ecological impacts that alter both the composition and function of ecosystems. In Manas National Park, the invasion by Chromolaena odorata and Mikania micrantha has been linked to a decrease in native plant diversity. Similarly, understorey invasive plant species in Palamau Tiger Reserve suppress tree seedlings and saplings, which pose a significant threat to forest regeneration and overall forest structure. Invasive shrubs like Ageratina adenophora and Lantana camara exhibit advanced functional traits, including higher specific leaf area, chlorophyll content, nutrient uptake and leaf litter decomposition compared to native shrubs, which facilitates rapid spread and ecosystem alteration. In addition to the ecological effects, these invasion affect herbivore food source and the livelihood of rural communities dependent on natural resources.
This table lists 54 terrestrial plant species (flora) that are invasive in India.
This table includes all 56 species across aquatic plants, inland fishes, marine species, and microbes found in freshwater/brackish water environments.