Causes of Biodiversity Depletion
Conversion of Forest Areas for Non-forestry Purposes: Due to various requirements like electricity, irrigation and drinking water, several dams have been constructed in the natural forests of the State, construction of roads for better access, power transmission lines, guest houses, dormitories, etc affecting or depleting the environment and the rich biodiversity. Even the making of trekking paths for various purposes affects the floral and faunal populations in different ways, directly and indirectly.
Encroachments and other Illegal Occupations:Due to population pressure and need for more areas to construct dwelling houses and practice cultivation of various domestic and economic species, people of the midlands and lowlands encroach forest areas , which are also regularized from time to time. Encroachers also rear domestic animals which are allowed to graze in natural forest areas, affecting the wild plant diversity and spreading diseases to wild animals. In many a case, diseases of the cultivated crops are also transmitted to the indigenous plant species. Poaching by encroachers and also their associates is yet another force, affecting the wild animal diversity of the State, that too at species level.
Plantation Establishment, especially of Exotic Species:In order to meet the timber and pulpwood requirements of the State, in the forested zone of the Highlands, more than 70000 ha of natural forests are converted into forest plantations, mainly of teak and eucalypts. Even though plantations of teak, which is an indigenous species, allow the sustenance of certain amount of plant diversity and provide habitats for less characteristic wild fauna, there is substantial reduction in both the components of natural biodiversity, due to the intense silvicultural operations carried out in such plantations. In the case of Eucalypts, which is an exotic species of very short rotation period, the growth and survival of wild flora and fauna in these plantations is very poor. Also, Eucalypt plantations, raised in the higher altitude grasslands of the State with unique biodiversity, are very harmful to the overall wealth of indigenous biological resources of the State.
Ecotourism and Pilgrimage: There are a few very popular pilgrim centers and tourist spots within the forest areas of the State like Sabarimala, Tekkady, Malayattoor, Athirappilly and Agasthyamala. People in large numbers traverse the forest areas for long distances on foot to reach the destinations, and in that process, pollute the environment and especially the water bodies, remove forest plants and leave aside used carry bags, bottles, food items, cloths, and so on. They also disturb the habitats, home ranges and movement patterns of wild animals. Ecotourism is yet another recent development in the State, wherein people in large numbers are allowed to go into both protected and other natural forest areas for recreation, carrying with them various items and discarding the packing items, carry bags, etc. there, degrading the environment. Tourists also take away with them flowers and other plant parts, seedlings seeds, animal parts, etc. affecting the regeneration of various plant and animal species. Such influx of people also become a disturbance factor to the wild fauna population, which require undisturbed forest areas for their free movement, feeding, breeding and multiplication.
Invasion of Exotic Weeds: The forest areas of the State, and especially the plantations within, have become the entry points and major habitats for the colonizing exotic weeds like species of Mikania , Lantana , Eupatorium , Mimosa , and so on . Because of their gregarious nature, these weeds not only suppress the native flora but also smother the trees in the plantations, leading to their poor growth or even death. Weeds also obstruct the free movements of wild fauna and reduce their fodder availability by suppression of the regeneration and growth of indigenous flora; at the same time, weeds are also not palatable to the wild animals. The soil is also much degraded, affecting the growth of indigenous plant species. All these factors act as driving forces to reduce the plant and animal diversity and the quality of the natural environment of the highland region.
Over-exploitation of Natural Resources: The rich floral and faunal components of the natural forests of the highlands are also the rich source of several timber and non-timber products. Because of the increasing demand, stemmed from the increased population, such items are being exploited legally and illegally, on a highly unsustainable manner, which depletes their source species and degrade their habitats. Timber of various kinds, non-timber products of plant and animal origin like medicinal plants, firewood, bark and bark products, honey, fur, horns, etc. all belong to this category of products.
Natural Calamities: Fire, landslides, soil erosion, wind, etc., occur erratically in the forested zone of the Highlands of the State. They act as driving forces to devastate the biodiversity and disturb the environment of the region. Many instances are also there when man induces fire to promote sprouting of grasses for their domestic animals, facilitate hunting of wild animals, collection of NTFPs, drive away wild animals, and so on. This, in turn, removes the plant diversity of extensive areas, affect the wildlife populations and degrade the environment to various degrees, depending upon the magnitude of the calamity.