Introduced as an ornamental plant from Latin America by the British in the 1800s, it soon spread throughout the country. By 2020, it is estimated to have occupied more than 40% of India’s tiger habitats.
Mudumalai Tiger Reserve The (MTR) in the Nilgiris is home to over 100 tigers, but has also suffered from lantana invasion, which has reduced vegetation and green cover in its core and buffer zones. That begs the question: Is MTR a dying forest?
The Tamil Nadu Forest Department’s Lantana weed eradication drive helped restore the vanishing Mudumalai Sanctuary and in doing so reduced human-wildlife conflict
But then, last year, there was a sudden change. Native species Vegetation has begun to grow throughout the reserve, and it appears that there is a complete revival of vegetation in the forest. wildlife officer He said this improvement was due to concerted efforts to remove invasive weeds, which helped restore the ecosystem.
The MTR covers 32,100 hectares of land Core Zone Spread over six ranges, the core zone has an additional area of 36,700 hectares, while the buffer zone spread over four ranges has an additional area of 36,700 hectares. Posing a threat to the ecosystem, invasive and exotic species such as Lantana camara, Senna spectabilis, Prosopis juliflora and Wattle are being removed. While the buffer zone—a scrub forest—is filled with various invasive species, the core zone, a dense forest, is filled with Lantana. The process of removing these invasive species began in early 2022.
About 20% of the area in the buffer zone of MTR is encroached. invasive speciesWhile at least 50% of the core zone is occupied mainly by lantana, the continuous removal of invasive plants has led to regeneration of natural grasses and other native species, says D Venkatesh, forest conservator and field director, MTR. “We maintain the cleared areas, but this process needs to continue for five years to make the forest free of invasive plants,” he adds. Though the invasive plants are initially uprooted completely, the seeds or small roots left behind pose a threat as their dormancy period can last up to 50 years, potentially giving them a chance to sprout again decades later.
Lantana camara is a perennial shrub that grows about 2 m to 5 m tall and forms dense thickets in various environments. “Lantana is the primary invasive species in MTR, preventing natural regeneration of grasses and native species. Once it is cleared, it is easier to remove secondary invasive plants,” says Venkatesh.
MTR is home to 25 species of grasses and legumes, including a variety of protein-rich grasses. “Wild animals help spread the seeds of these species in the forest, maintaining a natural cycle facilitated by wildlife in any forest land,” says Venkatesh.
“Even after the invasive plants are uprooted, the plants will grow again in the forest,” says Arun Kumar, deputy director, MTR-Buffer Zone. “This makes maintenance crucial. Without it, the initial efforts will go to waste. The health of the habitat is important as regenerated grasslands attract both small and large herbivores.”
The forest department has identified key routes in the reserve for removing invasive animals. In the vast 50-hectare area of the Singara range, where invasive animals have been removed and second year maintenance is underway, elephant herds are often attracted to the fresh grass, says Arun Kumar. “The health of a forest triggers a chain reaction in the ecosystem. Natural regeneration of grasses and legumes can help reduce conflict in marginal areas, as a healthy habitat keeps animals within their boundaries.”
Tamil Nadu Newsprint and Paper Limited is involved in the removal of the Senna spectabilis species found in the buffer zone of the MTR. “The bark of senna is so resilient that even if a small piece is left behind, it can regrow quickly. Hence, extra care is required during the removal process,” he says.
C Vidya, deputy director of MTR-Core Zone, says the presence of senna species is very low in the core area of MTR. “The real issue is lantana. But we cannot say that lantana is completely bad. It also provides ambush cover for carnivorous animals and fruits for birds and monkeys. In some ways, it also plays an eco-friendly role. If we focus only on tigers and herbivorous animals, lantana appears to be a threat.”
Vidya says 50% of the core area is affected by lantana. “Our fight against lantana is focused on important animal routes and rivers, ensuring that the removal does not leave the forest completely open. Rivers and water bodies are lifelines for animals during summer, and must be protected.”
The forest department has carried out individual assessments of each grid-compartment in the core zone. Officials say that since herbivorous animals do not consume much lantana, they do not contribute to its spread. Instead, lantana fruits are mainly dispersed by birds and monkeys. After passing through their digestive systems, the seeds become even more viable, and are more likely to germinate than through natural spread.
Vidya confirms that the flourishing of grasses and native species is a direct result of the removal of lantana. “When you remove invasive species, there are changes in the ecosystem, which increases the carrying capacity and utility index of the grasslands,” says Gajanan D Muratkar, professor of environmental science at Amravati University in Maharashtra and an advisor to 39 tiger reserves, including MTR. “An interconnected ecosystem is formed among the grasslands, which modifies the diversity index of the vegetation growing on the ground. This helps control small and large herbivores within these areas.”
Uprooting invasive species also restores soil characteristics such as moisture, colour and texture. He says natural regeneration of grasses leads to improved soil quality.
To remove lantana, the forest department relies on local tribal communities, who are skilled in the techniques needed for this task. However, the department faces limited funding for removal efforts, often using money from selling senna species to support the work.
In the core zone, 1,221 hectares of land has been identified as critical for lantana removal, of which about 355 hectares – 29% – has been cleared. In the buffer zone, 1,615 hectares of land has been cleared and maintained for the second year. This process continues in other areas as well, step by step. “We are seeing amazing results. Once fully completed, Forest ecosystem “It will sustain itself and support wildlife,” says Venkatesh.
