The Hindu : Karnataka / Bangalore News : Lantana threatens native species on B.R. Hills

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Lantana threatens native species on B.R. Hills

Divya Gandhi

‘This finding sounds a warning for other deciduous forests such as Bandipur, Nagarahole’

— FILE Photo: K. Murali Kumar

IN SEARCH OF FOOD: A Sambar stands amidst lantana shrubs at Bandipur National Park.

Bangalore: The ornamental but highly invasive shrub Lantana camara has colonised 80 per cent of the Biligiri Ranga Hills, threatening native plant species, wildlife habitats and local livelihoods, says a study.

In the study spanning 11 years, environmental scientists of the Ashoka Trust for Research in Ecology and the Environment (ATREE) have observed a doubling of the area covered by the exotic weed between 1997 and 2008, from 40 to 80 per cent.

The team recorded an eight-fold increase in the density of the plant from 5 per cent to 40 per cent in this timeframe.

The rapid lantana-proliferation that is transforming the once bamboo-dominated landscape of B.R. Hills is in keeping with what scientists have always observed about invasive species, explained Bharath Sundaram, doctoral student at ATREE.

“They take time to establish themselves but once they do so, they spread indiscriminately.” The study looked at 134 plots in the wildlife sanctuary where 16,000 plant stems were documented and compared for the prevalence of the shrub in 1997 and 2008. Lantana is native to South and Central America and was originally introduced in India in the 1800s by the British as ornamental hedges and garden plants.

The shrub has since grown to become one of the most widespread invasive species and is listed by IUCN-World Conservation Union as one of the world’s 100 most invasive species.

Several characteristics make lantana notoriously hardy and a tough competitor to local species. In the aftermath of a forest fire the plant regenerates from its rootstock faster than most native plants.

They flower and fruit year-round producing seeds that are dispersed widely by birds and animals.

They compete aggressively for nutrients in the soil.

The study sounds a warning for other deciduous forests in the Western Ghats where the shrub is known to be spreading, including Bandipur, Nagarahole and Mudumalai, says Ankila Hiremath, ATREE Fellow.

“We have anecdotal evidence of lantana spreading in these regions. What we do need is greater scientific monitoring to understand what is causing the spread, how it is impacting communities and habitats and how to control it.”

Lantana suppresses the regeneration of native species, impacting the livelihood of communities, such as the Soligas of B.R. Hills, who depend upon forest produce, she adds.

The changing ecosystem potentially reduces forage for herbivores while the plant is known to produce secondary compounds that are toxic to ungulates.

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