Ornamental tree species relentlessly invades Mudumalai Tiger Reserve, experts say native flora could be lost

In 2019, the Forest Department estimated that around 20 hectares of forests in the core area of the tiger reserve had become overrun with Senna spectabilis; this could pose a huge problem as wildlife depend on native species of flora

Dangerous trend: Invasive plants such as Senna Spectabilis arrest the growth of other indigenous species of trees.

A species of ornamental tree that was introduced to the Western Ghats, Senna spectabilis , has continued its relentless spread throughout the Mudumalai Tiger Reserve (MTR) in the last two years, threatening biodiversity in the tiger reserve’s core areas.

The species, which was introduced for its bright-yellow flowers that bloom during summer, is spreading rapidly and destroying native biodiversity in the process. Coupled with the continued presence of the Lantana camara , Eupatorium and Parthenium species, local ecologists fear that crucial wildlife habitats will face the pressures of this more recent threat to the landscape.

In 2019, the Forest Department estimated that around 20 hectares of forests in the core area of the tiger reserve had become overrun with Senna spectabilis . In the following years, it’s feared that the species could have doubled its coverage area.

Godwin Vasanth Bosco, a member of the Madras High Court-appointed expert committee on invasive species management and a Nilgiris-based ecologist, agreed that the species was spreading quickly. “One of the most concerning facets of the spread of this species is that it seems to be taking over moist-deciduous forests, which have a huge variety of native biodiversity,” he said.

Mr. Bosco said with invasive species like Senna spectabilis and Lantana camara, the areas they take over quickly lose native species of flora on which wildlife in the reserve depend on.

Shiny Mariam Rehel, programme co-ordinator for the Biodiversity Restoration Programme at Keystone Foundation, said that the profuse flowering of the species as well as other factors, lead to it spreading quickly. “We need to study the impacts this species has on ecology. At this point in time, we can only theorize about the potential negative impacts,” she said.

“Unless managed, large parts of the reserve could become populated by this species,” added Mr. Bosco.

When contacted, D. Venkatesh, Field Director of MTR, said that the Forest Department awaited policy-level decisions on how to manage and eradicate all invasive species from the Nilgiri Biosphere Reserve. “Once we get a clear roadmap, we will phase out invasive species of flora over a period of time,” he said.