GS Paper III

News Excerpt:

The unprecedented rise in the world’s invasive alien species contributes to 60 percent of extinctions and puts ecosystems at risk, causing serious concerns among environmentalists.

About the Invasion of Alien Species:

• Invasive species breed profusely in places far away from their original ecosystem, occupy more areas and soon alter their new territories while displacing the native species.
• Alien species are now one of the five major drivers of change in nature along with land and sea use change, direct exploitation of organisms, climate change, and pollution. 
• No place on the planet remains untouched by biological invasion, driving thousands of species to extinction.

About Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES):

• It is an independent body comprising more than 140 member states.
• It has released an assessment report “The Assessment Report on Invasive Alien Species and their Control”, the most comprehensive account so far, on invasive alien species and their impacts on the planet’s people and biodiversity. 
• It was prepared by 86 experts from 49 countries, who covered some 13,000 studies over four-and-a-half years. 

Key findings of the IPBES report:

• It acknowledges that invasive species will continue to spread to new geographies, with deep and irreversible impacts on the natural ecosystem.
• Human activities have caused the translocation of some 37,000 alien species across the planet, with 200 new alien species recorded every year.
• The proportion of established alien species known to be invasive varies among taxonomic groups, ranging from 6% of all alien plants to 22% of all alien invertebrates.
• Invasive alien species have contributed solely or alongside other drivers to 60% of recorded global extinctions, and are the only driver in 16% of the documented global animal and plant extinctions.
• At least 218 invasive alien species have been responsible for more than 1,200 local extinctions. 
• 85% of the impacts of biological invasions on native species are negative.
• It is estimated that by 2050, the total number of alien species will be 33% more than the number in 2005.

Impacts of Invasive alien species:

• There are humongous economic costs to these biological invasions. Invasive species do not just alter the local ecosystems but also afflict the local water, biology, and soil security making livelihood difficult, particularly for those who depend on ecosystems for survival.
• It is estimated that in 2019, such invasions cost the world $423 billion. 
• The vast majority of global costs (92 percent) accrue from the negative impact of invasive alien species on nature’s contributions to people or on good quality of life.
• While only 8 percent is related to management expenditures of biological invasions.

• Invasive alien species can add to marginalization and inequity, including, in some contexts, gender and age-differentiated impacts.
• An increase in invasive species means a loss in ecosystem services from forests and increased propagules (a vegetative structure that if detached from a plant can give rise to a new plant) into agricultural areas that will result in economic losses.
• The survival of apex predators like tigers depends on the abundance of herbivores, which in turn depend on habitats free from the negative impacts of plant invasions. 
• The proliferation of invasive plants jeopardizes these delicate ecosystems, with far-reaching impacts on species and people dependent on these ecosystems.

Impacts of Alien Species Invasion in Indian Perspective:

• A study, published in the Journal of Applied Ecology in October 2023, states that about 66% of the country’s natural systems are threatened with invasive species.
• The findings are a result of a national-level survey conducted in India, and note that 158,000 plots in 358,000 sq km of wild area are invaded by alien species. 
• 11 high-concern invasive plant species showed presence in 20 states of the country, including Lantana camara, Prosopis juliflora, and Chromolaena odorata.

• The study estimates that loss due to biological invasions would cost the Indian economy up to $182.6 billion.
• A different study titled “Massive economic costs of biological invasions despite widespread knowledge gaps: a dual setback for India”, published in the journal Biological Invasions in April 2022, found that in the last six decades invasive alien species cost India $127.3 billion.
• The data also indicates that the invasive cover increases up to a threshold with the rise in temperatures, and then declines in conditions of increasing rainfall, seasonal vegetation opening, and Human Modification Index.
  • The Human Modification Index is a set of 13 anthropogenic sensors that provide a cumulative measure of the impact of human modification on terrestrial lands across the planet.
• Savannas are reported to have the highest susceptibility (87 percent) to invasions, followed by moist grasslands and dry deciduous forests (72 percent each). 
  • Savannas were largely invaded by woody Prosopis juliflora, particularly surrounding semi-arid protected areas.
• Evergreen forests were found to be least suitable for invasive species, at 42 percent susceptibility.
• The study points out that Lantana Camara had the largest expanse, spread across 574,186 sq km, covering 50 percent of natural areas across all natural systems. 
• Mikania micrantha had the least expanse, stretching over an area of 148,286 sq km and covering 13 percent of the natural area, mainly moist grasslands and forests.

• Most species depict the eco-climatic affinity of these plants. 

• • 94 percent invasion of Prosopis juliflora coincided with dry grassland savannas and dry deciduous forests. 
  • Species like Senna tora, Xanthium strumarium and Mesosphaerum suaveolens were predominant in dry savannas and deciduous forests, 
  • Mikania micrantha and Ageratina adenophora were distributed in moist grasslands and evergreen forests.

• The Nilgiri Biosphere Reserve in the Western Ghats is one of the largest impacted invasion hotspot areas, dominated by Lantana camara, Prosopis juliflora and Chromolaena odorata.

• Fragmented forests of Central Indian Highlands were also largely and densely invaded forest systems, typically along the ecocline between dry and moist systems. 
• Ecocline: A gradation from one ecosystem to another when there is no sharp boundary between the two. It is the joint expression of associated communities (coenocline) and complex environmental gradients.

Major Reasons behind the increased invasion of alien species:

• Human modifications, shifting soil moisture regimes, historical propagation of invasive plants, and altered cycles of natural disturbances are the main driving factors behind the invasions. 
• The increasing work population densities and proportional increase of demand for food, infrastructure, energy, and socio-ecological drivers further threaten to intensify and possibly escalate the already accelerating invasion.
• Species have been moving to alien lands and becoming invasive since 1500 when colonization and global trade tentatively started. 
• However the growth of global trade and large-scale transport systems have caused a fivefold increase in the size of the global economy over the last 50 years, and it has resulted in alien species being recorded at an “unprecedented” rate.

Mitigation strategies for Invasive species:

• Mitigation strategies focus first on prevention, followed by early detection, rapid response, and finally containment, eradication, and control. 
• Public education campaigns, laws, and regulations should be implemented to prevent the future spread of invasive species.
• Managing invasive species demands more than mere removal, it necessitates context-sensitive restoration, stakeholder participation, and adaptive holistic policies that can enable positive changes.
• Effective control and management requires a clear understanding of species identification, biology, ecology, vectors of spread, and the most appropriate management methods. 

Way Forward:

The rise of invasive alien species poses a significant threat to global ecosystems, contributing to extinctions and economic losses. Mitigating this threat requires comprehensive strategies for prevention, early detection, and stakeholder participation. Addressing invasive species is crucial for preserving biodiversity and ecosystem services for future generations.