|
Management of an ecosystem
The Amazon Rainforest, Brazil
Location
Much of the Amazon is under threat from deforestation. One such area is Rondonia which lies on the southern edge of Amazonia. Since 1970, it has suffered some of the highest deforestation rates in Brazil.
Climate:
The equatorial climate is hot and wet all year. Rainfall is very heavy and falls most afternoons. The weather for each day is very similar. Temperatures hover around 28 degrees, whilst rainfall totals 1800mm per year.
Management of the ecosystem
|
Group/activity
|
Uses
|
Effect on environment
|
|
Cattle ranching
|
Over a quarter of the forest is cleared for cattle ranching. Most of the meat is sent to the USA for use in burgers.
|
Trees are cleared and do not grow again. The land becomes covered in grasses. As a result, the soil lacks nutrients. New grasses become weaker and weaker. Consequently the ranchers move onto a new area of land.
|
|
Mining
|
Mining companies use the forest to mine for minerals such as copper and iron ore.
|
Trees are cut down to build roads and waste deposits are fed into rivers, killing animals and fish.
|
|
Logging
|
International timber companies usually only want two or three specific species from the hundreds available (mahogany).
|
Although only two or three trees may be felled per hectare, many are destroyed in the process.
|
|
Shifting Cultivation
|
Local tribes use the forest for building materials, firewood, food, medicines, weapons and resins.
|
These people are shifting cultivators. They clear new patches of ground every three years, leaving old plots fallow for approximately 15 years allowing the fertility to return.
|
Effects of deforestation
•· Once the tree canopy has gone, the soil gets thinner and less fertile. Consequently, the crops yields fall.
•· Trees no longer intercept the heavy rain. As a result, erosion rates increase. The upper soil layers which contain most of the nutrients are washed away.
•· As more sediment enters the river, flooding becomes a greater risk further downstream. River conditions also change downstream and fish (an important source of protein) are threatened.
•· Farmland beside the river is flooded more regularly as deposits increase on the bed of the river. As a result, crops can be ruined and food supplies reduced.
•· Less dead vegetation falls to the ground and a hard crust forms. This means that less water is absorbed by the soil and surface run-off rates increase.
•· Less moisture can lead to increased risk of forest fires. In 1987, 83,000 sq km of forest went up in smoke. Therefore, more CO2 enters the atmosphere which leads to global warming.
Towards sustainable development:
•· Agroforestry has been encouraged. Farmers imitate the natural ecosystem, selecting appropriate crops that can cope with the conditions.
•· Restrictions made concerning the type of machinery used in the forest. This is done to limit noise and lower the general impact on wildlife.
•· Appropriate and Eco-tourism encouraged to educate people about the delicate balance in the rainforest and generate additional income.
•· Investment in the protection of forested areas.
•· Use of selective logging methods. A maximum limit on the number of trees to be felled in a certan area. Only trees above a certain age and size\are removed.
D.Drake 2008
|
