CHENNAI: By 2050, the state may lose 32% of evergreen forests due to the impact of climate change and extremely poor soil fertility that hampers forest regeneration.
These were the findings of a first-of-its-kind study and climate modelling by Centre for Climate Change and Disaster Management (CCCDM), Anna University. The study titled ‘Climate Risk Assessment in Forestry Sector Tamil Nadu’ was presented at senior forest officers conference on Monday.
The baseline data (1985-2014) show the state has 1,881 sq. km of evergreen forest, 13,394 sq.km of deciduous forest and 4,292 of thorn forest.
“Due to climate variables like increasing temperature and reduced rainy days, there will be a reduction of evergreen forest cover by 32%, deciduous forest by 18% during the period 2021-2050. The thorn forest cover will dominate, increasing by 71%,” said A Ramachandran, emeritus professor at CCCDM and member of TN Governing Council on Climate Change.
The analysis indicates the Nilgiris district is most vulnerable with maximum reduction in evergreen and deciduous forest types in the near future. The other districts showing reduced suitability for evergreen forest types are Dindigul, Coimbatore, Kanniyakumari, Tirunelveli and Tiruppur. The district with least reduction in habitat suitability for evergreen forest type is Krishnagiri.
Similarly, in Eastern Ghats, Salem is the most vulnerable with significant reduction in habitat suitability of evergreen forests followed by Namakkal in the near future.
Kurian Joseph, director, of CCCDM, said the changes occur due to historic blunders like felling of trees for timber.
Forest soil fertility dropping
Meanwhile, the climate studio of CCCDM has also done soil analysis in 560 carefully-selected locations in the forest areas to assess the current soil organic carbon (SOC), which has a direct correlation to the health of the forest ecosystem.
It was found that the existing SOC was an abysmal 0.8%. The bare minimum requirement to support forest generation is 1%. Ramachandran, who developed a web application on soil status for each district, told TNIE: “In some areas, the soil is literally dead with zero organic carbon. All the afforestation attempts by the forest department to improve the green cover will fail.”
The evergreen and semi-evergreen forest currently has SOC value ranging between 5 to 15%, which is healthy. “Our focus should be on thorn and deciduous forest areas, which are spread over 10.49 lakh and 5.31 lakh hectares respectively. Of these, 3.16 lakh hectares are highly degraded. The forest department needs to urgently enrich the soil in these degraded areas, of which 59,891 tonnes of compost is needed.”
Chief Wildlife Warden Srinivas R Reddy acknowledged that there was carbon and nitrogen depletion in the soil and there was little attention paid.
A Udhayan, PCCF and director of Advanced Institute of Wildlife Sciences, said the government has to think about bringing legislation for protecting soil. “Not many know that soil stores more carbon than evergreen forest.”