Information is also limited on the condition and value of biological resources, as well as uses and management techniques employed by traditional cultures over centuries.
Government policies designed to encourage some sectors, such as agriculture and forestry, also encourages the destruction of biodiversity. This is especially true if these policies do not incorporate sustainable development components as part of the development requirement. Lack of coordination between government agencies with overlapping responsibilities may also result in loss of biodiversity. The growth of such farming systems has often been at the expense of species-rich forests, wetlands, and diverse small-scale agricultural lands. Globally, there are inequities between rich and poor countries.
Jenkins, ed. The value of goods and services derived from biodiversity are typically not taken into consideration or undervalued, thereby promoting directly or indirectly their depletion. The value of biodiversity are almost totally ignored in national economic accounts because it is so difficult to value. However, when markets undervalue biodiversity, policies may encourage unsustainable or destructive activities.
In order to preserve and manage biodiversity:. These items will be permanently deleted and may not be recovered. Are you sure? Recently, many forests have been subjected to deliberately-set and accidental fires, to which they have little resistance, and to which they are rarely naturally subjected.
People often set fire to cut-over areas adjacent to forests to clear them of debris. These fires often get out of control and burn large areas, extend into the forest interior, and inhibit edge regeneration by killing pioneer forest vegetation.
ROOT CAUSES OF BIODIVERSITY LOSS
If conditions remain severe, the forest will recede and be replaced by scrub. Herbicides blow from cleared agricultural areas into forests, and exotic species introduced by farmers and ranchers spread, often displacing native species. These exotic organisms interrupt the forest ecosystem and, since they have few or no natural enemies in their new environment, they are difficult to eradicate. These invasions drive the loss of indigenous species. Canopy trees dominate the forest structure, and they provide fruits and shelter for many animals.
The mortality of trees in fragmented patches in Brazil has been found to be twice that of similar trees in the forest interior Laurance, et al. Large trees may be more vulnerable in fragmented forests because they are not as well buffered from wind and natural forces, because there are more tree parasites lianas , and because they are more subject to dessication at forest edges. Loss of these largest trees has several corollary effects — the alteration of biogeochemical cycles transpiration, carbon cycles , the reduction of species complexity, and the reduction of fecundity.
As mentioned above, large trees are essential habitats and food sources for many other organisms, both plant and animal; they are the source of much of the primary productivity of the forest; and they are responsible for many effects on the water and nutrient cycles. They are irreplaceable in the forest ecosystem.
Pathogens introduced through human activities by land use practices in areas surrounding the forest can be lethal to forest plants and animals. Fragments are much more easily accessible to human incursions than are intact forests. This leads to a variety of extractive activities within the forest interior. Intensive hunting, by depleting animal populations, inhibits plant reproduction, since many seeds can neither be dispersed, nor flowers be pollinated without them.
Where these seed dispersers have been eliminated, are at low population densities, or cannot move between forest fragments, seed dispersal will be very limited, and as a result tree species dependent upon animal dispersers may become locally extinct. As this forest becomes more and more fragmented, these birds are disappearing, so eventually the trees dependent upon them will be unable to replace themselves.
In some fragments, all large vertebrates including seed-eaters have been hunted to extinction, and in some places the fragments are so distant from each other that these animals cannot pass from one to another. The Alagoas curassow, a large fruit-eating bird of this area, is now extinct; many others toucans, aracaris, guans are endangered by hunting pressures.
Other species are sensitive to disturbance of their environment and they become locally extinct.
Wildlife and Habitat
In addition, in fragmented forests, seeds will frequently land in deforested areas where they are in the open, and exposed to heat, light and desiccation in which they cannot germinate, and the seedlings cannot survive. In Brazil, three to seven times as many Heliconia acuminata seedlings planted in continuous areas of forest germinated as compared to those planted in fragmented areas Bruna, Whatever the explanation for the lower rate of seedling germination in fragmented forests, whether due to inbreeding or other causes, fewer and fewer individuals in fragments grow to adulthood.
Those which do will breed, but since populations are small, inbreeding occurs and the downward spiral continues until the population becomes locally extinct. This effect is seen frequently in forest fragments. Turtles are heavily harvested for meat and their eggs are collected for food almost everywhere in the tropics and subtropics. Asian tropical freshwater turtles are in serious decline because they are extensively hunted for food or for use in traditional Chinese medicines.
Thousands of tons of live turtles are caught or sent to China annually, a completely unsustainable level of collection. There are apparently no turtles left in the wild in Vietnam for this reason Gibbons, et al. More than 80 species of Asian turtles are at such low population numbers that they will become extinct unless emergency measures — restrictions on international trade, increased habitat protection, captive breeding programs — are taken immediately.
Some of the hunting is done for subsistence purposes by villagers; some by farmers, miners and loggers, who live in the forest and use forest animals as a major food source; some by commercial hunters to supply urban markets.
This is a major source of income in many rural tropical areas. In Gabon alone, a tiny country, 3, tons of bushmeat are consumed annually Tuxill, Surveys of bushmeat consumption in Bolivia and Honduras showed that people will eat more bushmeat as their income rises, but when they become more affluent, consumption declines.
Consumption declines as well when bushmeat prices rise and the price of alternative sources of protein declines Wilkie and Godoy, Part of the remedy for overexploitation of wildlife resources, then, lies with improving the income levels of local residents so bushmeat becomes less attractive as a protein source , in increasing the costs of hunting, and in lowering the prices of alternative protein sources.
Many animals are trapped for the pet trade tropical fish, birds, reptiles, monkeys or for zoos or medical research. Other animals are trapped for their hides or furs, and some are killed because they live too close to human habitation and impinge on human activities. For instance, ocelots and other small carnivores may be shot when they attempt to prey on chickens or other domestic animals. Many tropical animals are hunted mercilessly for their value in traditional Asian medicines. Tigers, bears, deer, snakes, and many other animals are near extinction in many places because of this trade.
Tigers in India are almost gone and only tigers still exist in the wild anywhere Tuxill, Many of these animals, or their parts, are smuggled illegally from Southeast Asian and other countries to China and other countries with large Chinese populations for these uses. In these ways many tropical plants and trees depend upon animals, for, without them, they will not be able to reproduce. For instance, the seeds of Inga ingoides , a South American tree, are dispersed widely by the spider monkey Ateles paniscus.
This can be very detrimental to forests, which generally have high genetic diversity, because more homogeneous plants are generally less fit. The loss of elephants in African countries due to hunting has led to a loss of reproductive ability in many valuable tree species Tuxill, These techniques not only catch the few desired specimens, but kill all of the other animals in the area. Commercial fishing operations are not sensitive to issues of sustainability.
They catch as many marketable fish as possible, and intensify their efforts when fish populations drop declines due in the first place to overfishing. Such unsustainable fishing operations have led and are leading to severe declines in fish in major river systems within tropical rainforests see the case of the tambaqui, Part II, F3, b, ia. Fragmentation may be more serious than previously imagined because the consequences of fragmentation are not static, but progressive.
Eventually fragments may disappear altogether or undergo ecological collapse. Why do people heedlessly decimate the precious biodiversity of their planet?
Some of them feel they have no economic alternative, while others are driven by the desire for short-term profit. Pollution 5. Global Climate Change 6. Population Growth and Over-consumption 7. Illegal Wildlife Trade 8. Species extinction. A habitat is the place where a plant or animal naturally lives. Factors responsible for this are deforestation, fire and over-use and urbanization. Over-exploitation of resources has coasted more environmental degradation than earning. For example; shrimp farming in India, Thailand, Ecuador and Indonesia results in Wetland destruction, pollution of coastal waters and degradation of coastal fisheries.
Scientific studies have concluded that cost of environmental degradation resulting from shrimp farming was costing more than the earning through shrimp exports. These species become established in their new environment and spread unchecked, threatening the local biodiversity. These invasive alien species have been identified as the second greatest threat to biodiversity after habitat loss.