Restoration of the Tropical Dry Evergreen Forest
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The information contained in this case study is based on a summary of restoration activities in the Auroville Township and its bioregion by Paul Blanchflower.
Ecosystem description
This study is located in South India (latitude 11°55´ N and longitude 79°52´ E). The vegetation of the coastal region of the south-eastern peninsula of India has been defined as tropical dry evergreen forest (TDEF) (Champion and Seth, 1968). It has a narrow range some 500km long (north to south) and 50km wide at its broadest point. The area receives rain in both summer and winter monsoons, in a tropical dyssymetric regime (Meher Homji 1973).
It has been estimated that the proportion of natural TDEF remaining under forest cover is 4-5% (Meher Homji 1992; Wikramanayake et al 2002), with the vast majority of the remaining forest being highly disturbed. Field studies since the 1990s 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.
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).
The Auroville International Township is an international community established in 1968, dedicated to the ideals of human unity. It currently has a population of 1800 people drawn from 35 nationalities. Auroville is located on the Coromandel coastal plains in the state of Tamil Nadu, atop a pre-lateritic plateau with a maximum elevation of 52m above sea level.
Project goals
The initiative aims to restore the tropical dry evergreen forest around the Auroville Township in southern India.
Restoration activities
Initial restoration activities by the first Aurovillian settlers were largely aimed at creating shade and eliminating runoff of rainwater from the plateau. Activities included tree planting, of both exotic pioneer species such as Acacia auriculiformis, Cassia siamea, Eucalyptus sp., and Khaya senagalensis, and native pioneer species including Azidiracta indica, Bridelia retusa, Lannea coromandelica, Morinda pubescens, and Pterocarpus santalinus. The non-native species were largely more successful and became well-established.
Other activities included water and soil conservation work, including the establishment of bunding grids (raised banks of earth following contours or field boundaries) designed to contain rainwater. Check-dams and gully plugs were constructed in ravines to catch any remaining run- off, and existing catchment ponds were de-silted and enlarged. These measures helped to stop the erosion previously caused by water movement and, as the vegetation grew, helped Auroville to achieve its goal of ‘zero run-off’.
By the 1980s a marked difference could be seen in the ecology of the area. A canopy of pioneer species had been established, creating shade and thus the necessary environment for various indigenous plants to be re-established.
By the early 1990s the next stage of the restoration work was taking shape. A group of Aurovillians studied the botany of local plants and surveyed the remnants of the indigenous flora, primarily in reserved forests and temple groves. Plants were identified, seeds collected, and germination techniques determined, gradually establishing a database for some 300 native woody plant species. A herbarium containing documents and specimen sheets on the flora was established, as were plant nurseries containing tens of thousans of trees, shrubs, and lianas for planting out in the forests on an annual basis. Many of these species, some extremely rare, are now well established in the Auroville greenbelt, and some have begun to produce seeds.
Some of the common species of the forest include: Atalantia monophylla, Diospyros ebenum, Drypetes sepiaria, Garcinia spicata, Glycosmis mauritiana, Ixora pavetta, Lepisanthes tetraphylla, Manilkara hexandra, Memecylon umbellatum, Pterospermum suberifolium, and Syzygium cumini. Other important components of the ecosystem include liana such as Combretum ovalifolium and Capparis zeylanica, and both epiphytic (e.g. Vandia tesselata) and pseudobulbous (e.g. Eulophia epidendraea) orchids.
Results
As the forests have grown and native flora have returned, fauna has already returned to the area. The number of bird species increased from approximately 30 to over 90. Species of butterflies, moths, and other insects have taken advantage of the increased diversity of plant food sources, and their diversity has increased also. Many species of reptile are present, including monitor lizards, chameleons, starbacked turtles, and the star tortoises. Up to 19 species of snake are now considered common, including the indian spectacled cobra and Russell’s viper. Mammals whose populations have increased include the mongoose, black-naped hare, and civet cat. Porcupine have also been sighted. The forests of Auroville now cover some 2000 acres, and are managed towards a variety of ends. Some are designated as sanctuaries, while others are managed as mixed forests that in the long term will produce sustainable supplies of timber for the developing township. All the forests are managed with a view to biodiversity conservation and wildlife protection.
Threats
The range of the TDEF has been densely populated for many centuries and this is the main reason that is so rare and fragmented today. However the pressure continues to increase, and during the last ten years whilst surveys of the few remaining remnants have been undertaken a dramatic reduction in the vegetation has been documented. Many of the temple groves adjacent to agricultural land have been felled and cleared to make way for new fields. The other groves that are closer to urban situations have suffered from undergrowth clearance by pilgrims visiting the temples and so in many cases all that remain are the mature trees, which are not replaced when they die.
This situation, which is due to the rapid development in the area, gives greater worth to the restoration that has been carried out on the Auroville lands as this forest now provides a refuge for the genetic stock that is fast diminishing in the rest of the range.
Monitoring
The forest of Auroville have been studied over the years by many students, both indian and foreign, that have passed through. It provides an excellent environment to study the returning fauna and processes of vegatational sucession as well as specific ecological studies such as pollination and seed dispersal. There are three main centers of bioresource study, all of which are engaged in the development of educational materials for the local population using the information gained in the studies.
Bibliography
Champion, H. G. and Seth, V. K. (1968) A Revised Survey of the Forest Types of India.
Government of India
Meher-Homji, V.M. (1973) A phytosociological study of the Albizia amara Boiv. community of
India. Phytocoenologia 1(1): 114-129
Meher-Homji, V. M. (1974) The climate of Cuddalore – a bioclimatic analysis. Geographical
Rev. India. 36(1):1-22
Meher-Homji, V. M. (1992) A document to help formulate a conservation strategy for peninsular
India in relation to vegetation status and bioclimatic conditions. Final Tech. report
Pitambar Pant. Natl. Environ. Fel., Ministry of Environ., New Delhi.
Wikramanayake, E. et al (2002) Terrestrial Ecosystems of the Indo-Pacific – A Conservation
Assessment. Island Press, Washington DC