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Apex predator threatened by a plant

The National Tiger Conservation Authority (NTCA) released a study recently on the status of tigers, which has revealed alarming facts about their survival in the country, all thanks to multiple invasive plant species growing at a rapid rate.

Apex predator threatened by a plant

Representative image (Photo Credits: Justin Goerge)

CHENNAI: In a shocker to the conservationists, a report titled ‘Status of Tigers – Co-predators and Prey in India 2022’ released by the National Tiger Conservation Authority (NTCA) has pointed out that increasing invasion of plant species in the forest areas threatens tiger population and its conservation efforts as those alien plant species spread at a rate of around 730 sq km per year.

During the study conducted by NTCA and Wildlife Institute of India, it was found that 71% of the total sampled forested area of 3,58,551 sq km has been invaded by 11 high-priority invasive alien plant species including Lantana camara, Prosopis juliflora and Parthenium hysterophorus.

Large-scale invasion

The study also estimated that 66% of the total forested area in the country has been invaded by alien plants. India has a total forest cover of 7,13,789 sq km as per Forest Survey of India.

“The survival of tigers depends on high densities of herbivores that requires large wilderness areas with abundant nutritious forage; protecting such areas from deleterious invasive plants is thus a conservation priority,” the report said.

It added that savannas are the most invaded followed by moist grasslands and dry deciduous forests, while evergreen forests were relatively less invaded. Among the invasive plants, Lantana camara had the largest expanse of 5,74,186 sq km of natural areas and occurred across all natural systems, while the Mikania micrantha had a relatively restricted expanse, predominantly in moist grasslands and forests.

“Most species have an eco-climatic affinity. For example, 94% of Prosopis juliflora invasions 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, whereas Mikania micrantha and Ageratina adenophora were distributed in moist grasslands and evergreen forests,” the study found out.

The report has warned that the invasive alien species is spreading at an average rate of 729 sq km per year. Among the 11 invasive plants, Chromolaena odorata had the highest rate of invasion at around 2,000 sq km per year, while the Parthenium hysterophorus had the lowest invasion rate.

The highest invasion rates were recorded in the areas such as the multi-use areas of the Central Highlands, The Nilgiri Hills, Western Terai, and semi-arid savannas of Central India and the Deccan Peninsula.

The transition zone between grassy open ecosystems and forest systems had the highest invasion rates.

Issues facing TN reserves

While degradation of forest areas due to invasive species is a ubiquitous problem across the tiger habitats in the country, the study also identified localised issues affecting the tiger population in Tiger Reserves in Tamil Nadu.

• Anamalai tiger reserve (ATR): It faces threats due to high human-wildlife conflict and presence of many coffee and tea estates inside and around the periphery of the reserve. Also, activities like poaching, tourism and large numbers of human settlements affect tigers in ATR.

• Kalakad-Mundanthurai tiger reserve (KMTR): Waterbodies in this reserve are dammed up by the Tamil Nadu electricity board and extensive work is ongoing for hydro-power generation. This has led to the shortage of water in certain parts of the park. Densely-populated human habitations, tea and coffee plantations and linear infrastructure developments are resulting in a massive change of land use patterns.

• Mudumalai tiger reserve (MTR): Heavy tourist activities and heavy traffic on the 15 km stretch of Mysore-Gudalur National Highway and 14.3 km of State highway linking Theppakadu, Masinagudi and Ooty passing through the reserve is the biggest source of disturbance, which needs to be appropriately mitigated, the report added.

• Sathyamangalam tiger reserve (STR) “is plagued by the high number of human settlements interspersed between the park and the proliferation of invasive species. Traffic movements on NH 209, passing through the core area, is a major source of disturbance”.

• Srivilliputhur-Meghamalai tiger reserve (SMTR): Since it’s a newly-formed tiger reserve, the study suggests the strengthening of linkages so that the SMTR can become contiguous with KMTR cluster, which allows tigers to move between the habitats and establish new meta-population.

Depletion of wild prey

The study also pointed out that the depletion of prey impacts the tiger density negatively. “It’s clear that the forests of Chhattisgarh, Jharkhand, Odisha, parts of Bihar, southern Uttar Pradesh, and barring some prestigious protected areas in the north east (Kaziranga, Manas, and Orang), the entire region of the northeast, is depleted of wild prey. Tigers from these areas have become locally extinct or persist at very low densities, which are not sustainable in the long term,” the report said.

Moreover, the report also recommends the governments to ensure contiguous forest areas connecting tiger habitats to ensure gene-flow.

Meanwhile, a recently conducted tiger census has estimated 3,167 tigers in the country, which is higher than tiger population recorded during earlier censuses. There were 2,967 tigers recorded in 2018, and 2,226 tigers in 2014.

In 2006, there were only 1,411 tigers in India. Tamil Nadu has 306 tigers in its 5 tiger reserves.

During the initial stages of Project Tiger, 9 tiger reserves were announced and presently, there are 53. Total area of tiger reserves has been increased to 75,796 sq km from 18,278 sq km.

Avoided carbon emission

A recent study published in the Nature Ecology and Evolution, the online-only monthly journal, estimated that the tiger reserves in the country have avoided over 1 million tonnes of carbon emissions between 2007 and 2020. India has saved $6.24 million from avoiding social costs of emissions.

The study, which was aimed to establish the link between biodiversity conservation programmes and climate change mitigation programmes, has noted that the Project Tiger has averted forest loss of over 5,802 hectares, though some of the reserves, including Anamalai Tiger Reserve, did lose a certain amount of forest.

The loss of forest in the tiger reserves has been avoided due to stricter enforcement to preserve deforestation.

Rudhran Baraasu
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