Habitat+Destruction

=__**Human Impact: Habitat Destruction**__=

Habitat destruction remains perhaps the most important issue to consider when analyzing human impact on the environment. With an increasing human population and very limited space on this Earth, natural habitats fall to the wayside as human presence expands. Usually, habitat destruction occurs as humans use the land previously occupied by animals and plants and convert the land for agricultural use, resource exploration (for example, mining), or city and road construction.

Its effects are essentially the starting point for all other aspects of human impact, from loss of biodiversity to global warming/climate change.

Here we have divided habitat destruction into three separate (though interrelated) topics: deforestation, desertification, and marine environment destruction.

**What is Deforestation?**
Deforestation is the conversion of forest areas to non-forest land for use such as arable land, pasture, urban use, logged area, or wasteland. Generally, the removal or destruction of significant areas of forest cover has resulted in a degraded environment with reduced biodiversity. In many countries, massive deforestation is ongoing and is shaping climate and geography

**Causes of Deforestation:**

 * conversion of forests and woodlands to agricultural land to feed growing numbers of people
 * development of cash crops and cattle ranching, both of which earn money for tropical countries;
 * commercial logging (which supplies the world market with woods such as meranti, teak, mahogany and ebony) destroys trees as well as opening up forests for agriculture;
 * felling of trees for firewood and building material; the heavy lopping of foliage for fodder; and heavy browsing of saplings by domestic animals like goats.
 * the poor soils of the humid tropics do not support agriculture for long. Thus people are often forced to move on and clear more forests in order to maintain production.

**Effects of Deforestation:**

 * __The carbon cycle:__ Forests act as a major carbon store because carbon dioxide (CO2) is taken up from the atmosphere and used to produce the carbohydrates, fats, and proteins that make up the tree. When forests are cleared, and the trees are either burnt or rot, this carbon is released as CO2. This leads to an increase in the atmospheric CO2 concentration. CO2 is the major contributor to the greenhouse effect. It is estimated that deforestation contributes one-third of all CO2 releases caused by people.
 * __The water cycle__: Trees draw ground water up through their roots and release it into the atmosphere (transpiration). In Amazonia over half of all the water circulating through the region's ecosystem remains within the plants. With removal of part of the forest, the region cannot hold as much water. The effect of this could be a drier climate.
 * __Flooding__: is a quite serious consequence of deforestation. Clearing the forest dramatically increases the surface run-off from rainfall, mainly because a greater proportion of the rain reaches the ground due to a lack of vegetation which would suck up the excess rainfall
 * //__Soil erosion:__// With the loss of a protective cover of vegetation more soil is lost.
 * //__Silting of water courses, lakes and dams:__// This occurs as a result of soil erosion.
 * //__Extinction of species__// __which depend on the forest for survival:__ Forests contain more than half of all species on our planet - as the habitat of these species is destroyed, so the number of species declines (see Enviro Facts "Biodiversity").
 * //__Desertification__//: The causes of desertification are complex, but deforestation is one of the contributing factors (see Enviro Facts "Desertification")

Solutions for Deforestation:

 * Decreasing the need for the amount of products that are harvested from the rainforests. If all countries, especially developed ones, enforced programs that used recycling, the need for disposable products would be diminished and the loggers would not have a business. If the demand is cut off, there is no need for the supply.
 * Stop and even reverse deforestation of the preceding centuries through substituting timber by other products and more efficient use of land that had been farmed for many centuries.
 * Governments and Communities can all have an impact in reducing reforestation simply by using fewer goods that come as a result of deforestation. Re-use and recycling goods can be extremely helpful. Simple changes in lifestyle can have a dramatic impact

__Examples of Solutions put into Action__


 * In the People's Republic of China, where large scale destruction of forests has occurred, the government has in the past required that every able-bodied citizen between the ages of 11 and 60 plant three to five trees per year or do the equivalent amount of work in other forest services. The government claims that at least 1 billion trees have been planted in China every year since 1982
 * The Arbor Day Foundation's Rain Forest Rescue program is a charity that helps to prevent deforestation. The charity uses donated money to buy up and preserve rainforest land before the lumber companies can buy it. The Arbor Day Foundation then protects the land from deforestation. This also locks in the way of life of the primitive tribes living on the forest land

What is Desertification?:
Desertification is the process which turns productive into non- productive desert as a result of poor land-management. Desertification occurs mainly in semi-arid areas (average annual rainfall less than 600 mm) bordering on deserts. In the Sahel, (the semi-arid area south of the Sahara Desert), for example, the desert moved 100 km southwards between 1950 and 1975. The result is the destruction of topsoil followed by loss of the land's ability to sustain crops, livestock or human activity. The economic impact is horrendous, with a loss of more than $40 billion per year in agricultural goods and an increase in agricultural prices.


 * Climatic changes can trigger the desertification process
 * Overcultivation exhausts the soil. Cultivation of marginal lands, i.e lands on which there is a high risk of crop failure and a very low economic return, for example, some parts of South Africa where maize is grown.
 * Incorrect irrigation practices in arid areas can cause salinization, (the build up of salts in the soil) which can prevent plant growth.
 * Deforestation removes trees that hold the soil to the land. Destruction of vegetation in arid regions, often for fuelwood.
 * Overgrazing is the major cause of desertification worldwide. Plants of semi-arid areas are adapted to being eaten by sparsely scattered, large, grazing mammals which move in response to the patchy rainfall common to these regions.
 * Poor grazing management after accidental burning of semi-arid vegetation.
 * Droughts due to natural lack of rainfall can coincide with human causes and result in degradation of land
 * Increasing populations and poverty leads to increased usage and irresponsible usage of the environment

Effects of Desertification:
Desertification reduces the ability of land to support life, affecting wild species, domestic animals, agricultural crops and people. The reduction in plant cover that accompanies desertification leads to accelerated soil erosion by wind and water. South Africa losing approximately 300-400 million tonnes of topsoil every year. As vegetation cover and soil layer are reduced, rain drop impact and run-off increases. Water is lost off the land instead of soaking into the soil to provide moisture for plants. Even long-lived plants that would normally survive droughts die. A reduction in plant cover also results in a reduction in the quantity of humus and plant nutrients in the soil, and plant production drops further. As protective plant cover disappears, floods become more frequent and more severe. Desertification is self-reinforcing, i.e. once the process has started, conditions are set for continual deterioration. __Examples of Desertification Effects:__
 * About one third of the world's land surface is arid or semi-arid. It is predicted that global warming will increase the area of desert climates by 17% in the next century. The area at risk to desertification is thus large and likely to increase.
 * Worldwide, desertification is making approximately 12 million hectares useless for cultivation every year. This is equal to 10% of the total area of South Africa or 87% of the area of cultivated lands in our country.
 * In the early 1980s it was estimated that, worldwide, 61% of the 3257 million hectares of all productive drylands (lands where stock are grazed and crops grown, without irrigation) were moderately to very severely desertified. The problem is clearly enormous.

Solutions for Desertification:

 * To halt desertification the number of animals on the land must be reduced, allowing plants to regrow. Soil conditions must be made favourable for plant growth by, for example, mulching. Mulch (a layer of straw, leaves or sawdust covering the soil) reduces evaporation, suppresses weed growth, enriches soil as it rots, and prevents runoff and hence erosion. Reseeding may be necessary in badly degraded areas. Mulching and reseeding are expensive practices.
 * Use of good land management in semi-arid areas
 * Taking part in activities of conservation groups
 * Bring issues of desertification to the attention of government officials
 * Simple Changes in lifestyle can alter and deter desertification if such changes are made on a wide scale
 * Involvement in restoring and rehabilitation measures is most important within communities

What is Marine Environment Destruction?:
Marine environment destruction includes the destruction of marine populations, introduction of deadly chemicals, and severe alterations in the patterns of marine life. These are largely caused by human activity: Water pollution, over-fishing, habitat alteration, and the effects of climate change.

Causes of Marine Environment Destruction:

 * //Water Pollution//: includes sewage dumping from towns and cities (as well the unrelated trash lost in ocean waters such as fishing nets) and oil spills
 * //Over-Fishing//: simply means fishing to the point where entire species are endangered. (See [|here] for the USA Today article explaining why 90% of edible sea life will be lost by 2048.) Includes destructive human behavior such as exploding coral reefs to get more fish, and the technique called "bottom trawling" in which gigantic nets basically scrape the ocean floor clean of seafood.
 * //Habitat Alteration//: mostly refers to oil drilling (or other types of resource exploitation). Also includes effects of radioactivity and, again, over-fishing.
 * //Climate Change//: the important thing to remember here is that **heat is a pollutant**. Climate change means increasing temperatures and rising CO2 concentration in marine ecosystems.

Effects of Marine Environment Destruction:

 * //Production of deadly bacteria:// the toxicity of sewage is such that bacteria are produced in the water, including **hepatitis A, E. coli, and giardia**. Not only do marine animals and plants suffer, but human populations dependent on a single body of water can be deeply affected, too.
 * //Rapid algae and plant growth//: this sounds like it should be a positive, but in fact the excess nitrogen and phosphorus introduced into bodies of water by sewage and trash means that the "blooms" of plant life are detrimental to the ecosystem. These algae and plants grow so much that they block out sunlight (a condition worsened when they die and decay), which obviously hinders photosynthesis. And if oxygen can't be produced, the anaerobic bacteria at the bottom of water bodies can only produce acids. This not only increases acidity of the water body, but also means more production of nitrogen and phosphorus. And the cycle continues.
 * //Oil spills destroy coastal life in particular, and spread//: some estimates say that for every million tons of oil transported, one ton of oil is spill. The spills are dangerous for marine life, especially animals who find their coats covered in the slick, toxic substance. And water currents mean that a single spill can easily spread to far-reaching bodies of water. Even oil //drilling// leads to oil spills, no matter how much care is taken with it. Oil spills also create deadly oil slicks that harm coral reefs (whose importance is outlined below).
 * //Destruction of coral reefs//: using dynamite to blow up coral reefs affects entire ecosystems. Coral reefs form nurseries for 25% of the world's fish. If they are properly managed, they can support 15 tons of fish and other seafood per square kilometer a year (one billion people in the world depend on coral reefs for food and income). If not, then refer to the USA Today article. For more information on coral reefs, go [|here] (the WWF site has further links on marine environment destruction and conservation).
 * //Loss of medical advancement:// like tropical forests, coral reefs hold the key to many of the world's secrets. They are already being used to further the fight against cancer and AIDS. We are not helping the cause by exploding them.
 * //Disturbing bottom sediment//: bottom-trawling means that chemicals and pollutants accumulated at the bottom of water bodies are re-introduced into upper layers of water and re-suspended. They are mostly toxic and the marine life not used to living in its presence will die because of them. Oil drilling and other resource explorations also disturb the bottom sediment.
 * //Rising temperatures impacts ecosystems//: evidence has shown that phytoplankton (the primary producers of all ocean life) are drastically changing in response to climate change. As they form the basis of ecosystems, the impact on them trickles down to the rest of marine life.
 * //Loss of biological diversity//: the net effect of marine environment destruction is to kill off a whole lot of marine species. Refer to the USA Today article. Over-fishing, oil spills, destroying coral reefs... all these rob the planet of its many, many marine organisms.

Solutions for Marine Environment Destruction:

 * //Legislation//: government measures have been surprisingly effective in the past. Most prominent is America's **Clean Water Act** of 1972, which gave $50 billion to cities and states to control surface water pollution, setting the standard of "swimmable and fishable." And bans on fishing have been made in many different areas of the world, the most recent one being the fishing ban on the Philippines' Apo Reef, the second largest reef in the world.
 * //Improving transport and resource exploration techniques//: oil spills are just waiting to happen every time someone goes on cruise liner or lowers a giant drill into the ocean floor. If more effective ships and drills were built, the chances of disastrous oil spills could be minimized. In the case of ships, a better shot would be to use alternate energy sources to power the transportation.
 * //Information:// will probably, however, be the only thing that can save marine life. Educating people, making the cause known, is the only way to ensure that those taking strolls along the beach won't keep finding rusted whaling spears being washed onshore (or, even worse, people walking along beaches //throw// the rusted spear into the ocean).There are many organizations dedicated to marine conservation, including the Moore Foundation ([|http://www.moore.org/marine-conservation.aspx).]

Sources:
Deforestation [|http://www.umich.edu/~gs265/society/deforestation.htm] http://www.greenpeace.org/usa/campaigns/global-warming-and-energy/science/deforestation http://www.nationalgeographic.com/eye/deforestation/deforestation.html http://www.bcb.uwc.ac.za/Envfacts/facts/deforestation.htm http://www.greenpeace.org/usa/campaigns/forests/solutions-to-deforestation

Desertification [|http://pubs.usgs.gov/gip/deserts/desertification/] [|http://www.botany.uwc.ac.za/Envfacts/facts/desertification.htm] [|http://www.didyouknow.cd/deserts.htm] http://www.greenfacts.org/en/desertification/#6

Marine Environment Destruction http://marinebio.org/Oceans/Conservation/HabitatConservation.asp http://www.science.mcmaster.ca/biology/CBCN/genetics/fos_tig5.htm http://www.greenpeace.org/india/campaigns/save-our-seas/threats/habitat-destruction (More information on the nature of bottom sediments and bacteria: [|http://www.clean-flo.com/lake_aerator.html)] (The best two sites are below) [|http://www.umich.edu/~gs265/society/waterpollution.htm] http://www.american.edu/ted/projects/tedcross/xseap17.htm#r2

//This page by Montanna Cheng and James Mao (D Block)//