The toxic bracken ferns, a member of the delicate fern family, has colonised most grasslands in the Shola forests of the Western Ghats, causing habitat problems, particularly to the deer population.
The carcinogenic fern (genus Pteridium) has survived from the Paleozoic Era by dominating other ground-cover plants.
According to associate professor Smitha Hegde and researcher Sudha Sajeev, of Rondano Biodiversity Laboratory in St Aloysius College, the fern was the main cause of the shrinking vegetation in the grasslands.
The researchers discovered this during their visits to compile the first-ever field guide on ferns in the Kudremukh National Park.
Ruling out any ecological imbalance, Hegde felt the mineral-rich soil (iron ore content) and ‘fire lines’ (paths made by the Forest Department to control spread of forest fires) facilitated the fern’s rapid colonisation in the area.
Their findings on the habitat loss for deer and identification of 38 species of ferns, of which some are endemic to the Western Ghats, were submitted to Chief Conservator of Forests S Shantappa, who was transferred to Bangalore a week ago.
Shantappa, realising the magnitude of the problem, invited Hegde and members of the Indian Fern Society to discuss programmes to eradicate the weed recently.
Associate professor Smitha Hegde of Rondano Biodiversity Laboratory in St Aloysius College told Express that the Indian Fern Society members, after studying the Shola Forests, realised that the control of the fern was a complex issue. The bracken fern, which was an insect-repellent, was also resistant to fire, she said.
Earlier, the British government had tackled a similar problem of colonising ferns by launching an eradication programme, she recalled.
But the area of the grasslands in the Western Ghats covered by this fern ran into hundreds of hectares, she said.
The other suggestions of mixing soda ash to make the soil alkaline, as done in tea estates to discourage propagation of ferns, was found to be unrealistic as all human interventions were banned in the grasslands coming under the Kudremukh National Park, Hegde said.
The Forest Department is now toying with an option of growing a grass adaptable to local conditions that can out-compete the bracken fern.
On the bright side, ferns are nature’s marvel. Genoplastic in nature, ferns are metal indicators as they absorb heavy metals in the soil. They also have many medical applications. Oil from the root of a male fern plant can expel parasitic worms from the body.