GS Paper III

News Excerpt:

An invasive weed, native to North America, is posing a threat to the Chengalpet forests and Vedanthangal Bird Sanctuary’s local vegetation, ecology, and habitat of migratory birds.

About the Invasive species:

• Cuscuta dodder, a parasitic vine without roots, has infested trees in the reserve forests and has begun to spread inside Vedanthangal Bird Sanctuary.
• Dodder is a group of ectoparasitic plants (A group of organisms that infest the skin of human beings and other animals) in the genus, Cuscuta.
• These plants have very thin, sting-like twining stems that appear to be leafless. They do have leaves but they are reduced to tiny scales that are barely visible. 
• These have very low levels of chlorophyll, so are not green. 
• Because of the lack of chlorophyll, most produce very little food on their own and therefore depend on their host plants for nutrition. 
• The plants cover their host plants in a spreading, tangled mass of intertwined stems, especially when growing in full sun (twining and attachment is greatly reduced in shaded areas).
• It builds a canopy on the host plant and casts thousands of tendrils to form a dense spectacle before it strangles and eventually kills the host.
• The seeds of Cuscuta are spheroid and have a hard coat, which aids them to survive up to 50 years in dry storage and at least 10 years in the field. 
• Unlike root parasites, Cuscuta seeds do not require a specific stimulant to induce germination.
• It poses a serious problem in oilseeds, pulses, and fodder crops in the states of Andhra Pradesh, Chhattisgarh, Gujarat, Orissa, West Bengal, and parts of Madhya Pradesh under rain-fed as well as irrigated conditions.
• Legislation in 25 countries has listed this species as a ‘declared noxious weed’ with seeds and plant material denied entrance. 
• In the United States, it is the only weed seed whose movement is prohibited in every state.

Additional Information:

What is an Invasive species?

It is a species that is:

1. Non-native (or alien) to the ecosystem under consideration and,
2. Its introduction causes or is likely to cause economic or environmental harm or harm to human health.

How do Invasive Species Spread?

• Invasive species are spread primarily by human activities, often unintended. 
• People, and goods transported, travel quickly around the world and often carry uninvited species with them. 
• Invasive species can be introduced to an area by ship ballast water, firewood, accidental release, and by people. 
• Insects can be transported easily in wood, shipping palettes, and crates shipped across the globe. 
• Ornamental plants can become invasive after escaping into the wild. Released unwanted pets are another way invasive species are spread. 

What are the Impacts of Invasive Species?

• The introduction and establishment of invasive species (intentional or unintentional) can pose a significant threat to native and plant communities. 
• Invasive species can lead to the extinction of native plants and animals, destroy biodiversity, and permanently alter habitats. 
• Various impacts of invasive species can be economic and social, environmental and ecological, and on human health.

Vedanthangal Bird Sanctuary:

• The sanctuary comprises a small irrigation tank with an area of 40.348 ha in Vedanthangal village and the surrounding 5 km zone around the lake (declared as a bird sanctuary in 1998). 
• This bird sanctuary is one of the oldest bird protected areas in the country as well as in the State of Tamil Nadu. 
• This site is also recognized internationally, as an Important Bird and Biodiversity Area (IBA). 
• This Site is an Important Bird and Biodiversity Area (IBA) due to the presence of several species including the black-headed ibis (Threskiornis melanocephalus), Eurasian spoonbill (Platalea leucorodia), black-crowned night heron (Nycticorax nycticorax) and painted stork (Mycteria leucocephala). 
• The sanctuary is located in Maduranthagam Taluk of Chengalpattu District (erstwhile Kancheepuram) in the state of Tamil Nadu.

• This site was also declared a Ramsar site in 2022. 

• The wetland also provides educational and research opportunities. 
• The wetland also plays a vital role in nutrient cycling and groundwater recharge, which supports irrigation activities in the immediate vicinity.