47.3A: Habitat Loss and Sustainability
- Describe the effects of habitat loss to biodiversity and concept of sustainability
Habitat Loss
Humans rely on technology to modify their environment and replace certain functions that were once performed by the natural ecosystem. Other species cannot do this. Elimination of their ecosystem – whether it is a forest, a desert, a grassland, a freshwater estuary, or a marine environment – will kill the individuals within most species. Remove the entire habitat within the range of a species and, unless they are one of the few species that do well in human-built environments, the species will become extinct.
Effects of Habitat Loss on Biodiversity
Habitat loss is a process of environmental change in which a natural habitat is rendered functionally unable to support the species present. This process may be natural or unnatural, and may be caused by habitat fragmentation, geological processes, climate change, or human activities such as the introduction of invasive species or ecosystem nutrient depletion. In the process of habitat destruction, the organisms that previously used the site are displaced or destroyed, reducing biodiversity.
Human destruction of habitats has accelerated greatly in the latter half of the twentieth century. Natural habitats are often destroyed through human activity for the purpose of harvesting natural resources for industry production and urbanization. Clearing habitats for agriculture, for example, is the principal cause of habitat destruction. Other important causes of habitat destruction include mining, logging, and urban sprawl. Habitat destruction is currently ranked as the primary cause of species extinction worldwide.
Consider the exceptional biodiversity of Sumatra. It is home to one sub-species of orangutan, a species of critically endangered elephant, and the Sumatran tiger; however half of Sumatra’s forest is now gone. The neighboring island of Borneo, home to the other sub-species of orangutan, has lost a similar area of forest, and forest loss continues in protected areas. The orangutan in Borneo is listed as endangered by the International Union for Conservation of Nature (IUCN), but it is simply the most visible of thousands of species that will not survive the disappearance of the forests of Borneo. The forests are being removed for their timber, and to clear space for plantations of palm oil, an oil used in Europe for many items including food products, cosmetics, and biodiesel.
A five-year estimate of global forest cover loss for the years 2000–2005 was 3.1 percent. In the humid tropics where forest loss is primarily from timber extraction, 272,000 km 2 was lost out of a global total of 11,564,000 km 2 (or 2.4 percent). In the tropics, these losses also represent the extinction of species because of high levels of endemism.
Since the Neolithic Revolution, about 47% of the world’s forests have been lost to human use. Present-day forests occupy about a quarter of the world’s ice-free land, with about half of these occurring in the tropics. In temperate and boreal regions, forest area is gradually increasing (with the exception of Siberia), but deforestation in the tropics is of major concern.
Feeding more than seven billion human bodies takes a heavy toll on the earth’s resources. This begins with the appropriation of about 38 percent of the earth’s land surface and about 20 percent of its net primary productivity. Added to this are the resource-hungry activities of industrial agribusiness: everything from crops’ need for irrigation water, synthetic fertilizers, and pesticides, to the resource costs of food packaging, transport (now a major part of global trade), and retail.
Sustainability
Sustainability is a concept that describes how biological systems remain diverse and productive over time. Long-lived and healthy wetlands and forests are examples of sustainable biological systems. For humans, sustainability is the potential for long-term maintenance of well-being, which has ecological, economic, political, and cultural dimensions. Sustainability requires the reconciliation of environmental, social, and economic demands, which are also referred to as the “three pillars” of sustainability.
Healthy ecosystems and environments are necessary for the survival and flourishing of humans and other organisms, and there are a number of ways to reduce humans’ negative impact on the environment. One approach is environmental management, which is based largely on information gained from earth science, environmental science, and conservation biology. A second approach is management of human consumption of resources, which is based largely on information gained from economics. A third, more recent, approach adds cultural and political concerns into the sustainability matrix.
Loss of biodiversity stems largely from the habitat loss and fragmentation produced by human appropriation of land for development, forestry and agriculture as natural capital is progressively converted to human-made capital. At the local human scale, sustainability benefits accrue from the creation of green cities and sustainable parks and gardens. Similarly, environmental problems associated with industrial agriculture and agribusiness are now being addressed through such movements as sustainable agriculture, organic farming, and more-sustainable business practices.
Key Points
- Habitat destruction renders entire habitats functionally unable to support the species present; biodiversity is reduced in this process when existing organisms in the habitat are displaced or destroyed.
- Clearing areas for agricultural purposes is the main cause of habitat destruction; other principal causes include mining, logging, and urban sprawl.
- The primary cause of species extinction worldwide is habitat destruction.
- Sustainability is a term that describes how biological systems remain diverse and productive over time, creating the potential for long-term maintenance of human well-being.
- Reducing negative human impact requires three concepts: environmental management, management of human consumption of resources, and awareness of cultural and political concerns to increase sustainability.
Key Terms
- sustainability : Configuring society so that each person can meet their own needs and greatest potential, while preserving biodiversity and natural ecosystems, and planning for future generations to maintain this potential.
- endemism : The ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere.
- biodiversity : The diversity (number and variety of species) of plant and animal life within a region.