Invasive plant species threaten 66% of India’s natural systems

Subject: Environment

Section: Biodiversity

Context:

About 66 per cent of the country’s natural systems are threatened with invasive species, according to the report published in the Journal of Applied Ecology.

Details of the study:

The study offered the first account indicating distribution status of high-concern invasive plants spread across the country.
The findings are a result of a national-level survey conducted in India.

Key findings:

The 11 high-concern invasive plant species that showed presence in 20 states of the country included Lantana camara, Prosopis juliflora and Chromolaena odorata.
The economic loss due to biological invasions would cost the Indian economy up to $182.6 billion.
The data indicated that invasive cover increases with temperatures up to a threshold and declines with increasing rainfall, seasonal vegetation opening and human modification index.
- Human modification index is based on 13 anthropogenic sensors that provide a cumulative measure on impact of the human modification of terrestrial lands across the globe.

Spread and threats of Invasive Alien Species (IAS):

Susceptibility to invasive species: Highest in Savannas (87%), followed by moist grasslands (72%), dry deciduous forests (72%) and evergreen forests (least susceptible at 42%).
The suitability of individual alien plants and its drivers varies for each species.
Some invasive species are: Prosopis juliflora, Senna tora, Xanthium strumarium, Mesosphaerum suaveolens, Mikania micrantha and Ageratina adenophora.
Invasive species that have invaded most are: Lantana camara (Maximum expanse at 50%), Mikania micrantha (least expanse at 13%).
Nilgiri Biosphere Reserve in Western Ghats was one of the largest impacted hotspot areas due to invasion dominated by Lantana camara, Prosopis juliflora and Chromolaena odorata.
Southern Eastern Ghats were found to host the most densely invaded landscapes with maximum vegetation of Prosopis juliflora and Lantana camara.
Central Indian Highlands: Invaded along the ecocline between dry and moist systems by Prosopis juliflora.

Causes of these invasions:

Human modifications, shifting soil moisture regime, historical propagation of invasive plants and altered cycles of natural disturbances.
Human modifications include: Increasing work population densities and proportional increase of demand for food, infrastructure, energy and socio-ecological drivers.

Source: DownToEarth