A recent report in the Journal of Applied Ecology reveals that invasive species threaten around 66% of India’s natural ecosystems. The study provides the first account of the distribution and impact of invasive plants across the country.
- A nationwide survey underpins these findings. It found invasive species in 158,000 plots spanning 358,000 square kilometres of wild area.
- 11 particularly harmful invasive plant species, including Lantana camara, Prosopis juliflora, and Chromolaena odorata, were found in 20 Indian states.
- The survey covered substantial portions of various ecosystems: 31% of savannas, 51% of dry deciduous forests, 40% of moist deciduous forests, 29% of semi-evergreen forests, 44% of evergreen forests, and 33% of moist grassland savannas.
Biological Invasions Impact On The Indian Ecosystem
- Indian ecosystems face significant harm due to biological invasions.
- These invasions could potentially cost the Indian economy as much as $182.6 billion.
- Researchers found that 53% of surveyed plots contained at least one of 11 high-risk invasive plants.
- These plants have invaded 72% (equivalent to 254,880 square kilometers) of the land.
- There’s a correlation between temperature and invasive cover. The latter increases with temperature up to a certain point, then decreases.
- High-risk invasive plants were found in 22% of natural areas and could potentially pose a threat to 66% of these areas.
- The data suggests that invasive cover decreases with increasing rainfall, seasonal vegetation change, and a global measure of human impact called the “human modification index.”
- Savannas showed the highest susceptibility to invasions at 87%, followed by moist grasslands and dry deciduous forests at 72%.
- Evergreen forests were least susceptible to invasive species, with a susceptibility rate of 42%.
- The susceptibility of individual alien plants and their drivers varied for each species.
Distribution Of Invasive Species In Indian Biodiversity Hotspots
- The study reveals that Lantana camara is the most extensive invasive plant, covering half of the natural areas. It spreads over 574,186 square kilometers.
- Mikania micrantha, on the other hand, has the smallest expanse. It covers only 13% of the natural area, particularly in moist grasslands and forests. Its area is about 148,286 square kilometres.
- The invasion of Prosopis juliflora, accounting for 94%, aligns with dry grassland savannas and dry deciduous forests.
- Senna tora, Xanthium strumarium, and Mesosphaerum suaveolens are primarily found in dry savannas and deciduous forests.
- Mikania micrantha and Ageratina adenophora mainly distribute in moist grasslands and evergreen forests.
- The Nilgiri Biosphere Reserve in the Western Ghats is heavily impacted by the invasion of Lantana camara, Prosopis juliflora, and Chromolaena odorata.
- Southern Eastern Ghats have been identified as densely invaded landscapes due to the widespread vegetation of Prosopis juliflora and Lantana camara.
Impact Of Invasive Plants On Tiger Habitats
- The findings from the regions with a high tiger population hold great importance and relevance.
- Tigers, as apex predators, rely on abundant herbivores.
- Herbivores, in turn, require habitats free from invasive plant impacts.
- Invasive plant growth can destabilise these delicate ecosystems.
- This destabilisation can deeply affect both species and people depending on these ecosystems.
- Project Tiger is designed as a beacon to monitor changes in carnivores, herbivores, and their habitats.
- Invasive plants can dramatically change habitats.
- These plant invasions can trigger complex ecological shifts across various biomes.
Addressing Invasive Species Impact
- The surge in population density amplifies the demand for food, infrastructure, and energy. This leads to an alarming increase in ecological invasions.
- Invading species disrupt forest ecosystems, causing a decrease in their beneficial services and leading to economic losses in agriculture due to the spread of propagules (plant parts that can grow into new plants).
- Rise in invasive plants means less food for herbivores. This can lower their population and, in turn, reduce food availability for apex predators.
- The management of invasive species goes beyond simple eradication. It requires:
- Restoration that takes into account the ecological context.
- Inclusion of stakeholders in the process.
- The formulation of adaptive, comprehensive policies to foster positive change.