Alien invasive species are species that threaten native plants and animals or other aspects of biodiversity. They are found in all plant and animal groups as competitors, predators, pathogens, and parasites, and have infiltrated nearly every type of native ecosystem. An alien plant, also known as exotic, introduced, foreign, non-indigenous, or non-native, is one that has been intentionally or unintentionally introduced by humans from one region to another. In this article, we will discuss Invasive Alien Flora of India which will be helpful for UPSC exam preparation.

Invasive Alien Flora

• A naturalised species is an alien plant that has escaped from its original ecosystem and is reproducing on its own in the regional flora.
• Naturalized aliens that become so successful that they displace native biota or threaten valuable environmental, agricultural, or personal resources by causing damage are considered invasive.
• For thousands of years, humans have transported animals and plants from one part of the world to another, sometimes intentionally for social or personal gain, and sometimes unintentionally.
• Most such introductions fail, but when they do become established as an invasive alien species, the consequences can be disastrous.
• They can harm the environment, the economy, and even human health.
• Invasive species change the environment they invade and are difficult and expensive to control once they have colonised a landscape due to their phenotypic plasticity (the ability to adapt to environmental stress).
• Invasive plant species use the soil structure and microenvironment to their advantage by producing allelochemicals that destroy native species and local biodiversity.

Invasive Alien Flora - Harmful Effects

• According to the Convention on Biological Diversity, invasive alien species are the world's second leading cause of biodiversity loss, imposing significant costs on agriculture, forestry, and aquatic ecosystems.
• In fact, introduced species threaten native biodiversity more than pollution, harvesting, and disease combined.
• Invasive species are homogenising the world's flora and fauna and are recognised as a primary cause of global biodiversity loss.
• Bio-invasion is a type of biological pollution that has a significant impact on global change and is one of the leading causes of species extinction.
• Once established, some alien species have the potential to displace or replace native plant and animal species, disrupt nutrient and fire cycles, and alter plant succession patterns.

Invasive Alien Flora of India

Needle Bush

• Nativity: Tropical South America
• Distribution: Throughout India
• Remarks: Found on rare occasions in thorny scrub and dry degraded forests, where it forms dense thickets.

Black Wattle

• Nativity: South East Australia
• Distribution: In India, it is found in the Western Ghats
• Remarks: Introduced in the Western Ghats for afforestation. After a fire, it regenerates quickly and forms dense thickets. It can be found in high-altitude forests and grazing lands.

Goat Weed

• Nativity: Tropical America
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Weed that causes havoc in gardens, cultivated fields, and forests.

Alternanthera paronychioides

• Nativity: Tropical America
• Distribution: Throughout India
• Remarks: Occasional weed along the edges of tanks, ditches, and marshy areas.

Prickly Poppy

• Nativity: Tropical Central & South America
• Distribution: In India, it is available throughout the country.
• Remarks: An aggressive coloniser. Winter weed found in cultivated fields, scrub lands, and along the edges of forests.

Blumea eriantha

• Nativity: Tropical America
• Distribution: In India, it is available throughout the country.
• Remarks: An aggressive coloniser. Abundant along railway tracks, road sides, and degraded forest lands.

Palmyra, Toddy Palm

• Nativity: Tropical Africa
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Cultivated and self-sown, occasionally found gregarious near cultivated fields, scrub lands, and waste lands.

Calotropis / Madar, Swallo Wort

• Nativity: Tropical Africa
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Common in cultivated fields, scrub lands, and wastelands.

Datura, Mad Plant, and Thorn Apple

• Native: Tropical America
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Occasional weed on disturbed ground.

Water Hyacinth

• Nativity: Tropical America
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Abundant in still or slow-moving water. Harmful to aquatic ecosystems.

Impatiens, Balsam

• Nativity: Tropical America
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Common along streams in moist forests and on railway tracks; also grows wild in gardens.

Ipomoea / Pink Morning Glory

• Nativity: Tropical America
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Common weed in marshy areas and along the edges of tanks and ditches.

Lantana camara / Lantana, Wild Sage

• Nativity: Tropical America
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Common weed of forests, plantations, habitation, wastelands, and scrublands.

Black Mimosa

• Nativity: Tropical North America
• Distribution: Found in Himalayan and Western Ghats ranges in India.
• Remarks: An aggressive coloniser. It infiltrates water courses and seasonally flooded wetlands.

Touch-Me-Not, Sleeping Grass

• Nativity: Brazil
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Common weed of cultivated fields, scrub lands, and degraded forests.

4 '0' clock plant

• Nativity: Peru
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Runs wild in gardens and close to human settlements.

Parthenium / Congress grass, Parthenium

• Nativity: Tropical North America
• Distribution: Throughout India
• Remarks: Aggressive coloniser. Common weed of cultivated fields, forests, overgrazed pastures, wastelands, and gardens.

Prosopis juliflora / Mesquite

• Nativity: Mexico
• Distribution: Throughout India
• Remarks: An aggressive coloniser. Common weed of wastelands, scrublands, and degraded forests.

Townsend grass

• Nativity: Tropical West Asia
• Distribution: Throughout India
• Remarks: Common along rivers and streams.

Invasive Alien Plants in Nilgiri Biosphere Reserve

• Invasive alien species are non-native plants, animals, pathogens, and other organisms that can cause economic or environmental harm or have a negative impact on human health.
• Because of its rapid growth and coppicing ability, invasive plants, particularly Senna Spectabilis, pose a major threat to the Nilgiri forest region.
• During the summer, the dense foliage stunts the growth of other indigenous tree and grass species, causing a food shortage for the wildlife population, particularly herbivores.
• Furthermore, wildlife would not eat the tree's leaves because they were unpalatable to them.
• The plant began to spread in nearby tiger reserves, including Bandipur and Nagarhole in Karnataka and the Mudumalai tiger reserve in Tamil Nadu.

Conclusion

One of the most serious threats to native species and ecosystems is biological invasion by alien species. The consequences for biodiversity are massive and often irreversible. Invasive alien plants pose a significant threat to biodiversity in catchment areas, potentially disrupting ecosystems' delicate natural balance. We rely on biodiversity for water, food, wood, clean air, medicine, and many other things, so it is critical that we protect this resource.

FAQs

MCQs

1. Which of the following is an example of an invasive alien species in India?

A) Banyan Tree

B) Lantana camara

C) Mango Tree

D) Neem Tree

2. What is the primary characteristic of an invasive alien species?

A) Native to the region

B) Harmful to the ecosystem

C) Beneficial for the local economy

D) Requires minimal water

3. Which of the following invasive alien species is a major threat to aquatic ecosystems in India?

A) Parthenium hysterophorus

B) Eichhornia crassipes

C) Cuscuta

D) Lantana camara

4. How can invasive alien species be controlled in India?

A) By using pesticides

B) Through public awareness campaigns

C) By encouraging the spread of IAS

D) By introducing more alien species

5. What is one of the main consequences of the spread of invasive alien species?

A) Increased agricultural productivity

B) Disruption of natural ecosystems

C) Reduction in pollution levels

D) Improvement in biodiversity

GS Mains Questions and Model Answers

Q1: Discuss the impact of invasive alien species on India's biodiversity. How can India effectively manage these species?

Answer: Invasive alien species pose a serious threat to India’s biodiversity by outcompeting native species for food, space, and sunlight, disrupting natural ecosystems, and sometimes causing extinctions. Species like Lantana camara and Eichhornia crassipes are invasive plants that damage ecosystems. To effectively manage IAS, India should strengthen monitoring and reporting systems, promote public awareness about their impacts, establish rapid response teams to address new invasions, and regulate the trade of exotic species. Additionally, ecological restoration and removal of invasive species must be prioritized to protect native flora and fauna.

Q2: Examine the role of government policies and legal frameworks in addressing the challenges posed by invasive alien species in India.

Answer: The Indian government has enacted several laws to address the threats posed by invasive alien species, including the Biological Diversity Act (2002), which mandates the regulation of foreign species. The National Biodiversity Action Plan (NBAP) also emphasizes the prevention of biological invasions. The government has been actively involved in monitoring and controlling IAS, but there is a need for more stringent enforcement and effective policy implementation. The lack of coordination between various government agencies and insufficient funding for IAS management programs are key challenges that must be addressed to improve the effectiveness of these policies.

Q3: Critically analyze the role of public awareness in controlling the spread of invasive alien species in India. How can public participation be increased?

Answer: Public awareness plays a crucial role in controlling the spread of invasive alien species by educating citizens about the dangers posed by non-native species and encouraging responsible behaviors such as avoiding the introduction of alien species into new environments. Community-based monitoring programs, educational campaigns in schools, and collaborations with environmental NGOs can help build awareness and participation. To increase public involvement, it is essential to create platforms for citizen science, organize workshops on biodiversity conservation, and promote sustainable practices at the grassroots level. Public engagement will foster a collective responsibility toward protecting ecosystems.

Previous Year Questions on Invasive Alien Species

1. UPSC CSE 2020

Question: Examine the impacts of invasive alien species on the ecosystems of India. What measures have been taken to manage them?

Answer: Invasive alien species like Lantana camara and Eichhornia crassipes pose severe threats to India’s biodiversity by outcompeting native species and disrupting ecosystems. Management efforts include the Biological Diversity Act and the National Biodiversity Action Plan, which focus on preventing and controlling the spread of IAS. However, more targeted action, such as ecological restoration and public participation, is needed to effectively address this issue.

2. UPSC CSE 2019

Question: Discuss the role of public policy in mitigating the threats posed by invasive species in India. How can India enhance its biosecurity measures?

Answer: Public policies like the Biological Diversity Act regulate the introduction of alien species, but implementation remains weak. Enhanced biosecurity measures include better border control, stricter enforcement of regulations, and investment in research on invasive species. India can also work on early detection and rapid response strategies to curb the introduction and spread of IAS.