TDEF and Auroville

Tags: eco restoration afforestation indigenous species regeneration tropical dry evergreen forest TDEF

Tropical dry evergreen forests  (TDEF) are found in tropical regions with seasonal rainfall, resulting in several months of severe drought. Such conditions have provided the selective pressures for the evolution of highly distinctive vegetative forms.TDEF is thought to be the "most threatened of all major tropical forest ecosystems". It covered once 40-45% of all tropical lands. Today the intact TDEFs comprise only 1-2% of their original area. And this remaining area is exposed to a high level of threat.TDEFs were exploited from early times for their valuable timber. As the tree canopy giants were selectively harvested in the 1800s, many TDEFs became progressively used for cattle grazing, farmland or extractive production of fuel wood and charcoal. At present, fragmented TDEFs and adjacent areas are often used for livestock grazing.

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The indigenous forest of the Auroville bioregion is called Tropical Dry Evergreen Forest (TDEF). In India it extends as a coastal belt from Ramanathapuram in the south of Tamil Nadu to Visakhapatanam in Andra Pradesh (latitude 11°55´ N and longitude 79°52´ E).It has a narrow range some 500km long (north to south) and 50km wide at its broadest point.It provides a rare biological richness due to its high species abundance. The TDEF it is now close to extinction, it is estimated that only 0.1% survives most of it in the form of sacred groves and in isolated reserve forest patches. Sacred groves are clusters of trees around local temples. Those trees have not been cut since they stand on sacred ground. Field studies suggest that only 5% of the remaining forest cover is anything close to primary forest. Consequently the TDEF of southern India is considered to be one of the rarest types of forest ecosystem in the sub-continent. The southern Indian TDEF ecosystem was largely neglected until the late 1970s but since then there has been growing interest from a range of groups including universities, NGOs, and the Forest Department.

Around 200 years ago the Auroville Plateau was covered in jungle and herds of elephants roamed the area. A stone was discovered in Kilianur dating from 1750 that described the local king hunting for elephants and tigers in the nearby forest. Later people started to log trees in order to drive away the tigers. The tropical forest diminished rapidly and gave space to the growing cities like Pondicherry or Kalapet. The valuable timber of the local TDEF was exported. This was accelerated by the policy of the British Raj to allocate plots of land to anyone that would clear the jungle and start cultivating it for at least a year.  Much of the cleared land was left fallow, and the strong monsoon rains washed away the precious top soil, erosion inevitably began. In the 1950’s the last remaining forests (around 2,000 mature neem trees) were cut down for timber to make boats. In less than 200 years, what once had been forest had turned into an expanse of baked red earth scarred with gullies and ravines which had been carved out by the monsoon floods. Each year tons of the remaining topsoil were swept into the nearby Bay of Bengal.


Related video: Preserving the TDEF

Source: Sustainable Future, CSR


The TDEF ecosystem has a canopy rarely higher than 8m tall, with trees interlinked by lianas. The forest floor has a thick layer of leaf matter that is efficiently recycled by a dense mass of feeder roots in the top centimeter of the soil.  Since the nutrient wealth of the forest is held in the canopy, when the forest is cut the soil is quickly leached of nutrients by intense monsoon rains. Species remaining in the forest despite the degradation include porcupine (Hystrix indica), mongoose (Herpestes edwarsi), and civet cat (Viverricula indica).

TDEF is a highly divers vegetation, it contains over 160 woody species of which around 70 are found within the climax vegetation. The TDEF is composed predominantly of trees and shrubs which have thick, dark green foliage throughout the year. Today there is hardly any of this forest that remains free from human interference, and most of it is little more than degraded thorny thickets, lacking in the inherent nobility of the climax vegetation.  Including all the herbaceous species that grow in ecological niches within this forest type, the number of species approaches 1000. It is recorded that out of this more than 600 are used for mankind, either medicinally, culturally or in religious rituals.

The forest comprises six vegetative elements: trees, shrubs, lianas, epiphytes, herbs and tuberous species. In the pristine state, these components weave together to form a complex, diverse habitat that is home to myriad animal species, as well as a host of microbes. Not more than 500 acres of undisturbed forest remains and many of the listed species of trees, shrubs and lianas are on the verge of extinction.
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