Seeds of invasive species dispersed

Study finds native mammals disperse ‘Senna Sepctabilis’ in the Western Ghats

The ‘Senna Sepctabilis’ plant is posing a serious threat to the wildlife habitat

A recent study has revealed that native mammals disperse the highly invasive ‘Senna Sepctabilis’ in the Western Ghats. The plant is posing a serious threat to the wildlife habitat in the Wayanad Wildlife Sanctuary as well as the adjacent Bandipur and Mudumalai Tiger Reserves in Tamil Nadu and Karnataka.

The study, carried out by the Ashoka Trust for Research on Ecology and Environment (ATREE), Bengaluru and the Ferns Nature Conservation Society, Mananthavady, in the Wayanad Wildlife Sanctuary, found that mammals such as Asian elephants, chital and the Indian-crested porcupine were dispersing seeds of this tree. The study was published in a recent edition of the international journal Biotropica .

The study was carried out by analysing the faecal samples of wild animals and livestock, collected from the sanctuary.

The researchers found that native wide-ranging animals, especially elephants, are capable of dispersing seeds over long distances. The study warns of seed dispersal by such animals facilitating the fast spread of this species to large areas in forest landscapes.

Major drivers

“The nutrient content, taste and smell of the pods might have been the major drivers attracting the herbivores,” N.R. Anoop, research scholar, ATREE, who led the team, said.

“As a single seed pod of the plant contains more than a hundred of seeds, a single mature tree could produce more than a lakh of seeds a year,” Mr. Anoop said.

The invasive plant is spreading rapidly in the sanctuary and it suppresses the natural growth of other plants. A very large portion of the sanctuary and adjacent tiger reserves are densely covered by this species now.

“Interestingly, this species suppresses the growth of other invasive species like lantana and eupatorium” P.A. Vinayan, a member of the team, said. “As large mammals like elephants are involved in the seed dispersal of this tree, we should very soon expect its invasion to the wet forests, which hold very rich plant diversity in the Western Ghats,” Mr. Vinayan, said.

The rampant growth of the species is already posing a threat to the wildlife habitat from Tholpetty range of the sanctuary to the Thirunelly elephant corridor. If the authorities failed to adopt steps to contain the spread of the plant, it would pose a threat to the open patches and grasslands of the adjacent Brahmagiri Wildlife Sanctuary in Karnataka too , Mr. Vinayan said.

Thyagarajan Ganesh and Sandeep Sen of the ATREE are the other members of the team.