Chennai: Rain forests degradation threatens endemic rivers

Chennai: Concerned over the degradation of forests and to improve the quality of rainforests officials and ecologists attached to the Tirunelveli forest division are now working on recent satellite images and research papers dating back to 1970s.

“The rain forests of Tamil Nadu, which serve as lifeline for rivers in southern Tamil Nadu, had extensively degraded since 1973. Satellite images since 2004 and field samples taken over a period of 40 years for various research journals focusing Kalakad Mundanthurai Tiger Reserve (KMTR) in Tirunelveli has shown that 16 per cent of evergreen rainforests have degraded to semi-evergreen forests”, explains A. Venkatesh, chief conservator of forest and field director, KMTR, who is now on a mission to reclaim the leased out tea estates that were once pristine Shola forests.

Of the total 316 square km of original rainforests in KMTR, only a patch of 188 square km of the forest is left and it is deteriorating further due to climate changes. Similarly, the dry evergreen and moist deciduous forests of KMTR have also lost their land cover to the inferior type of forests.

The grassland covering about 73 square kilometres is largely distributed among the Kodayar, Manjamparai and adjoining areas of Agasthyamalai region. The area under grassland has shown a significant increase of 166 per cent during the period 1973-2004 and this continues.

The changes in the vegetation cover based on digital classification through satellite images shows a significant decrease of evergreen forest mostly to semi-evergreen forest types. Of the total area covered by natural vegetation (857 square kilometres) the evergreen and semi-evergreen forest occupied 60 per cent of the area. In 2004, the evergreen forest had diminished by 40 percent due to its land cover loss. Whereas the semi-evergreen forest gained by 36 percent to 265 square kilometres. 

Several data on forest degradation have been published in international journals by scientists associated with the International Water Management Institute, Colombo, National Remote Sensing Centre, Hyderabad and International Centre for Integrated Mountain development, Kathmandu, the conservator explained. 

Deforestation to turn most perennial rivers seasonal by 2025

Perennial rivers in Tamil Nadu are on the verge of losing their originality and by 2025 most of the rivers will be turn seasonal due to the forest cover degradation and climate change along Western and Eastern Ghats, warn experts in conservation and forest ecology.  

“The evergreen forests of the Anamalai Tiger Reserve comprising Valparai and KMTR have undergone extensive degradation in the past few decades. For instance now there is good rainfall in the upper altitude areas of Sathyamangalam tiger reserve due to continuous forest, but there is a seasonal deficit in the rainfall in the lower patches due to development and depletion of forests”, explains conservation scientist Dr A. Kumaraguru, member, Sathymangalam Tiger Conservation Authority.

Habitat destruction for tea estates, road development, plantations, industries not only affect the quality of forests but also pose severe threat to wildlife that are endemic to rainforests. Species like King Cobra, Lion tailed Macaque, Nilgiri Langur and Hornbill will face adverse effects if evergreen rain forests deplete and succeed into semi-evergreen forest rivers like Thamirabharani, Bhavani, Moyar and Siruvani will be affected, Kumaraguru said explaining that tropical rainforest soils contain rich mineral nutrient and act like giant sponges soaking up moisture and then release it gradually preventing floods and ensure that that the rivers flow even during periods of lower rainfall and summer, he added.