Biodiversity benefits humanity in many ways. It helps make the global economy more resilient, it functions as an integral part of our culture and identity and it’s even linked to our physical health.
However, despite its importance, Earth’s biodiversity has decreased significantly over the last few decades. The core threat to biodiversity on the planet and therefore a threat to human welfare is the combination of human population growth and resource exploitation. The population requires resources to survive and grow and those resources are being removed unsustainably from the environment. Man has begun to overuse or misuse most of the natural ecosystems.
Due to this unsustainable use of resources, once-productive forests and grasslands have been turned into deserts and wastelands have increased all over the world. Mangroves have been cleared for fuel wood and prawn farming, which has led to a decrease in the habitat essential for breeding of marine fish. Wetlands have been drained to increase agricultural land. These changes have grave economic implications in the longer terms.
The current destruction of the remaining large areas of wilderness habitats, especially in the diverse tropical forests and coral reefs, is the most palpable threat worldwide to biodiversity. A report finds that around 1 million animal and plant species are now threatened with extinction, many within decades, more than ever before in human history.
Scientists have estimated that there are around 8.7 million species of plants and animals in existence. However, only 1.2 million species have been identified and described so far, most of which are insects. The number of species, however, is likely to be greater by a factor of at least 10. Plants and insects as well as other forms of life not known till date are continually being identified in the world’s hotspots of diversity. Unfortunately, at the present rate of extinction, about 25 per cent of the worlds ‘species will undergo extinction fairly rapidly. This may occur at the rate of 10,000- 20,000 species per year at a rate 1000- 10, 0000 times faster than the expected natural rate.
Human actions could well exterminate 25 per cent of the world’s species within the next twenty or thirty years. Much of this mega-extinction is related to human population growth, industrialization and changes in land use patterns. A major part of this extinction will, of course, occur in bio-rich areas such as tropical forests, wetlands and coral reefs. The loss of wild habitats, due to rapid human population growth and short-term economic development, is the contributor to the rapid destruction of biodiversity.
Island flora and fauna, which have high endemism in small isolated areas surrounded by the sea on all sides, have so far been most seriously affected by human activity. This has already led to the extinction of many island plants and animals (the Dodo in Madagascar is a well-known example). Habitat loss also results from the introduction of species from one area into another by humans, disturbing the balance in existing communities. In the process, the purposely or accidentally introduced organisms (some notorious examples being Eupatorium, Lantana, water Hyacinth, Congress grass or Parthenium) have led to the extinction of many species and have also adversely affected human health. The loss of species occurs due to the destruction of natural ecosystems, either for conversion to agriculture or industry, or by over-extraction of their resources or through pollution of air, water and soil.
In India, forests and grasslands are continuously being converted to agricultural land. Encroachments have been repeatedly legalized. Similarly, our natural wetlands systems have been drained to established croplands resulting in loss of aquatic species. Grasslands that were once sustainably used by a relatively smaller number of human beings and their cattle are either changed to other forms of use or degraded by overgrazing.
Our natural forests are being deforested for timber and replanted using teak, Sal or other single species for their timber value. Such monoculture plantations do not support the same biological diversity as a multistoried natural forest, which has a closed canopy and a risk undergrowth of vegetation; nor do they nourish the soil. When excessive firewood is collected from the forest by lopping the branches of trees, the forest canopy is opened up and this alters the local diversity.
Foraging cattle retard the regeneration of forest as young seedlings are constantly trampled. The ever increasing human population pressing on the fringes of our forest areas degrades forest ecosystems and the not-so-subtle daily encroachments gradually decrease the buffer zones and the forested areas. A primary example is the Gir National Park, the last bastion of the Asian lion- a metre-gauge railway runs through the park, a state expressway and three temples. This is a major factor to consider in evaluating the quality of the ecosystem. Repeated fires started by local grazers to increase the growth of grass ultimately reduce regeneration and lower the diversity of plant species. Without an alternate source of fodder, this pressure cannot be decreased.
Another factor that disrupts forest biodiversity is the introduction of exotic weeds, which are not a part of the natural vegetation. These weeds spread at the expense of the diverse range of indigenous undergrowth species. The impact on the diversity of insects, birds and other wildlife species, though not adequately studied, is quite obvious. In our country a variety of traditional farming techniques evolved over several centuries-slash- and –burn cultivation in the Himalayas and rab, lopping off tree branches to act as wood-ash fertilizers in the Western Ghats are two such systems. When the human population in these areas was low, these were sustainable methods of agriculture. Unfortunately, these areas now have a large number of people who subsist largely on forest agriculture. These methods are now unsustainable and are leading to loss of forest biodiversity.
The overharvesting of fish, especially using large trawling boats, is leading to serious depletion of fish stocks. Marine turtles, which are inadvertently caught in fishing nets, are being massacred off the coast of Orissa. The rare whale shark, a highly –endangered species, is being killed off the coast of Gujarat. Specific threats to certain animals are related to large economic benefits. The skin and bones of tigers, ivory of elephants, horns of rhinos and perfume of the musk deer are extensively used abroad. Bears are killed for their gall bladders.
Corals and shells are also collected for export or sold on the beaches of Chennai, Kanyakumari and the Andaman and Nicobar islands. Tortoises, exotic birds and other small animals are packed into tiny containers and smuggled abroad for pet trade. A variety of wild plants with real or sometimes dubious medicinal values are being over-harvested. The commonly collected plants include Rauwolfa, Nux vomica, Datura and others. The garden plants collected for illegal trade include orchids, ferns and mosses.
We do not see all the varied functions that biodiversity plays in our lives because they are not obvious. We rarely see how they control our environment unless we study nature closely, over a period of time. We tend to overlook nature’s inter-relationship and take short-term actions that can have a serious impact on biodiversity and its habitats. Humans do not have the right to do this. We only share this planet with millions of other species that also have a right to survive. It is morally wrong to allow our actions to lead to the extinction of other species.
(The views expressed are personal)
