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.
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.
According to P. Arunkumar, Deputy Director, MTR (Buffer Zone), the Forest Department estimates that the species has spread over 800-1,200 hectares of the buffer zone.
Local residents said they had noticed the species seemed to be spreading faster over the last five years, during which time the trees seem to have become more common.
The Forest Department is still demarcating areas where the species is spreading, but officials stated that they were looking at ensuring that the removal of the trees begins before the problem becomes more difficult to manage.
According to officials, policy-level discussions are under way on the Tamil Nadu Newsprint and Papers Limited (TNPL) plan to use wood from Senna spectabilis from the MTR for paper-making. They said the funds so raised would be used in eco-restoration to bring back native species.
Mr. Arunkumar said that 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.
Senna spectabilis, along with Lantana camara, is among five major invasive weeds that had taken over vast swathes of the Nilgiris, with wattle being the other major invasive species. Eucalyptus and pine, though exotic, do not spread as quickly as the other species and are considered easier to manage, Forest Department officials said.
Officials also stated that the Madras High Court was hearing petitions calling for the removal of exotic species, and that judges from the court had inspected the Tiger Reserve this year to monitor progress in the removal of invasive species.
Top Forest Department officials said that Senna spectabilis was spreading fastest in the Singara and Masinagudi forest ranges in the MTR buffer zone, as well as in Kargudi range in the core area of the reserve. They said that policy-level decisions are being formulated that will allow the TNPL to remove the species from the landscape. They added that 125 hectares of Lantana camara was removed in 2021, and that 70 hectares of the weed are to be removed this year.