Invasive Species

Syllabus: General Studies Paper 3

An invasive species, Senna spectabilis, an exotic tree, has taken over between 800 and 1,200 hectares of the buffer zones of the Mudumalai Tiger Reserve (MTR) in the picturesque Nilgiris hill district. 

The Forest Department is coming up with a comprehensive strategy to deal with the spread of the invasive species, which continues to spread rapidly in the buffer zone.

About 

• Introduced as an ornamental species and for use as firewood from South and Central America, the species has become highly invasive in the Sigur plateau in both the core and buffer zones of the MTR.
• Over the last few years, its bright yellow flowers have become more visible across the Tiger Reserve, with conservationists stating that the invasive weed has a negative effect on local biodiversity, crowding out native species and limiting food availability for wildlife.
• The Forest Department was also formulating a 10-year-plan to systematically remove Lantana camara, the other major weed that poses a threat to biodiversity in both the core and buffer zones of the Tiger Reserve.

Five major invasive weeds

• Senna spectabilis
• Lantana camara
• Wattle  
• Eucalyptus and 
• Pine
• Eucalyptus and Pine though exotic, do not spread as quickly as the other species and are considered easier to manage,

Invasive Species

An alien species is a species introduced outside its natural past or present distribution; if this species becomes problematic, it is termed an invasive alien species. The climate change, movement of people and goods around the world increases the threat for introduction of invasive alien species.

Threat posed by invasive alien species on native ecosystem:

• Invasive alien species are the most common threat to amphibians, reptiles and mammals on The IUCN Red List. 
• They may lead to changes in the structure and composition of ecosystems detrimentally affecting ecosystem services, human economy and wellbeing.
• Worldwide, invasive alien species constitute one of the leading threats to biodiversity, second only to the destruction and fragmentation of entire habitats.
• Alien species may threaten indigenous species by competing with them for the same resources, by predation, by spreading diseases or parasites, or by cross-breeding with these species in the wild.
• Alien species are also known to have changed the structure of food chains and to have affected the functioning of entire ecosystems.
• Invasive alien species cause harmful social impacts and substantial financial losses to a variety of actors. 
• Many invasive alien species are major pests for agriculture and forestry industries.
• Fishing and fish farming may also suffer from the spread of invasive alien species. 
• Alien species can also pose a health hazard or function as disease carriers.

Examples of Invasive species:

• Ipomoea (Ipomoea carnea)
• Mimosa (Mimosa himalaica)
• Parthenium (Parthenium hysterophorus) is believed to have come to India as contaminants in a consignment of wheat imported from the U.S. in the 1950s
• Lantana (Lantana camara) was brought by the British as ornamental plants from South America two centuries ago.
• Bombax ceiba (locally called Semul)
• Largestroemia speciosa (locally called ejhar)