Land use is the way in which humans modify and utilize natural environment for agricultural, industrial, urban, and other similar purposes.
Land use has major environmental impacts on water, soil, animals and plants, and can lead to serious environmental damages if not adequately regulated. Common reasons for land degradation include:
- Lack of land planning or proper implementation
- Financial incentives encouraging erroneous land use
- Large scale planning based on the principle of maximized use of land resources
Because of industrialization and urban growth, there is less and less land to support a growing population. Developing countries who fight poverty and whose populations are exploding the fastest often have the largest land use conflicts. Indonesia and Brazil have the most severe deforestation, accounting for more than half of emissions from land use changes. Some other worldwide statistics include:
- 65% of Africa’s agricultural land has been affected by soil degradation.
- Arable (cultivated land) is lost at 30-35 times the historical rate.
- Potential productivity loss due to soil degradation is an estimated 20 million tons of grain per year, worldwide.
- 1/3 of the earth’s surface has been turned to desert.
Each year about 13 million hectares of the world’s forests are lost due to deforestation.
- Almost 1 million acres of land, including cropland are paved every year for roads and parking lots.
- 1.4 billion tons of ore are extracted every year to produce steel primarily for automobiles, household appliances, and construction.
Deforestation is the removal of forested areas for alternative land use, such as agriculture and cattle-ranching, mining, oil and gas, dams, and logging. Forests cover around 30% of the world’s land area, with 10 countries accounting for two-thirds of all forest area: Australia, Brazil, Canada, China, the Democratic Republic of the Congo, India, Indonesia, Peru, Russia and the United States of America.
South America suffered the largest net loss of forests between 2000 and 2005, followed by Africa, which lost 4 million hectares each year. Fires in the Amazon have been seen from space. Primary forests (forests with no visible signs of human impact), account for about 36 percent of total forest area, but are lost at a rate of 6 million hectares a year through deforestation. Indonesia has the fastest deforestation rate of any single country in the world.
Most countries have national forestry management plans. Because the countries with the most valuable forests tend to be those at a relatively early or middle stage of development, their land management processes easily succumb to corruption and are too weak to withstand global demand for timber. Many countries also lack law enforcement and legislation for land protection. As a result, powerful corporations take over local resources easily, encouraging illegal logging and land-grabs for agriculture.
Forests make an enormous contribution to the biosphere in the following ways:
- Forests influence local climate and rainfall through respiration
- Forests store water and filter it through their root structure
- Forests protect soil quality and quantity
- Forests are habitat for species biodiversity
- Forests are a source of natural healants
One hectare of Amazon rainforest can contain more plant species than the whole of Europe. Some believe the current rate of plant and animal extinction by deforestation is 1,000 times greater than that in pre-human history.
Agricultural Land Use
Agriculture uses land for the production of crops, meat and vegetable products, fibers and fuels. Approximately 68% of all agricultural land is used in the production of live stock, and total farmland increased by 5 million hectares annually between 1992 and 2002. The use of land for agricultural purpose has had a devastating impact on our environment, such as massive soil erosion, deforestation, loss of biodiversity, and water pollution from agricultural waste and pesticides. As the world’s population continues to grow rapidly, the challenge is to find a sustainable way of producing enough food while avoiding negative environmental outcomes.
Over 1/3 of the world’s population lives in urban areas. Urban land use is when land is used for building cities and towns. Urban development results in profound changes to the landscape, such as habitat destruction and deforestation to construct buildings and roads. Buildings in a city require natural resources like timber and materials from mines. Condensed populations must also use land to store large amounts of waste (including hazardous waste). A condensed population also puts stresses on the supply of energy, water, clean air, food, and wastewater treatment.
Cities are often unsafe, unhealthy, and poor, especially in the developing world.
- Less than 35% of cities in developing countries have treated wastewater.
- ½ to 1/3 of solid waste in low and middle income countries is not collected.
- 5.8% of children in cities in developing countries die before age 5.
Natural soil erosion is a process by which water or wind breaks down, carries away, and then deposits soil layers. Human caused erosion occurs more quickly with negative impacts in water and soil quality. Humans accelerate erosion with:
- Burning biomass
- Poor agriculture methods
Coastal erosion is also a problem. Coasts erodes from:
- Rising sea levels
- Natural run-off and storms
- Ocean waves
- Human use of beaches
- Construction near the shore.
Africa experiences some of the greatest erosion in the world. The continent loses 18 billion tons of top soil every year and parts of Western Africa have as much as 98 feet of coastal erosion every year.
Desertification is when land becomes depleted of nutrients and moisture, unable to support life. These dried up lands are in half of the world’s countries. Some causes include:
- Climate variations and drought
- Over pumping
- Over cultivation
Dried out land affects people and their environment in the following ways:
- Diminished food production from declining soil productivity
- Increased flooding
- Reduced water quality
- Increased sedimentation in rivers and lakes
- Health problems from dust
- Loss of livelihood, forcing people to migrate
Soil salinity is a measurement of the salt content of the soil, which affects crop yield. Salts occur naturally and are a product of soil and rock weathering. Water evaporates, leaving the excess salt behind. Salty soil is more crumbly and has less water permeability, preventing vegetation growth. Excess salinity comes from:
- High evaporation
- Low precipitation
- Restricted soil drainage from sandy, rocky, or dense soil (because of naturally occurring minerals or over plowing)
Land use and natural resource extraction
Resource extraction is a sure way to degrade land because dozens of mineral and metal pollutants get left behind during and after mining. After miners extract all resources available, they often abandon the degraded land. Mining produces waste in the following forms:
- Slag (left over waste after refinement)
- Sludge (fine mud from drilling)
- Tailings (mining residue)
- Leaching (left over waste after removing ore with water)
(For more information see our Pollution page)
Impact on Species
Habitat destruction is the greatest factor in driving species to extinction. Wildlife cannot live where we have constructed buildings, filled in wetlands, grown crops, or burned down the forest. Species also decline when their habitat is cut into smaller pieces (fragmentation). Fragmented lands are more likely to be developed. Fragmentation also affects the genetic biodiversity of species living in them.
One example is the Ethiopian wolf. Land clearing eliminates their habitat and forces wolves to encroach on human settlements, threatening humans and livestock. Wolves become more threatened when trapped, shot, or poisoned. They also loose rich genetic biodiversity by interbreeding with domestic dogs. Domestic dogs also cause Ethiopian wolves to spread the rabies disease.
Impact on Climate Change
An earth covered in healthy soil and vegetation is important for the balance of climate. Degrading earth’s natural areas can disrupt that balance. The UN’s Intergovernmental Panel on Climate Change reports that 10-30% of human caused air emissions are due to land use changes. Trees capture carbon dioxide by taking it into their cells through photosynthesis. They store the carbon in their bodies; a tree is comprised of about 50 percent carbon.
In the U.S. forests absorb between one million and three million metric tons of carbon dioxide each year, which offsets 20-46% of the country’s greenhouse-gas emissions. Also, if temperatures continue to increase, land uses will change. Fertile lands will become too hot and dry to farm. (For more on climate change, visit our Global Warming page)
Impact on Human Populations
The impacts listed above directly affect human populations, and can indirectly reduce human health. The way humans use land affects safety, and air and water quality. Erosion and desertification can lead to increased flooding and landslides. Urbanization increases human vulnerability to new and old disease epidemics.
Intensely farmed land and soil degradation thwarts the hunger problem. Land quality is important for the economy and health of a population. 57% of Asia’s poor and 51% of Africa’s poor live on low quality lands. Negative environmental impacts also contribute to financial stress. Ecological devastation in China, along with pollution, causes an economic loss equivalent to 10% of the country’s GNP.
- Some common national policies include the following:
- Chemical and hazardous waste prevention/limits
- Landfill and nuclear waste storage regulations
- Clean up and re-use of land
- Zoning laws for type and density of buildings
- Pre-building requirements to analyze potentially impacted natural resources
- Urban sprawl limits
An example of an urban sprawl law was set in the state of Oregon 20 years ago. The state required each community to project 20 year growth and then draw a city boundary. The law forced new development to be more dense and built in existing urban areas.
Local and national laws protecting agricultural resources include regulations and permits on the following:
- Farming on steep slopes
- Farming, grazing, or logging close to stream banks
- Growing plants with high water demands in arid areas
- Water rights and pumping
- The number and density of trees harvested
- Large scale ranches
NGOs and some national governments implement large scale conservation plans for endangered plants and animals, and habitat areas like forests and wetlands. According to the World Resources Institute, there are about 8,163 protected areas (marine and land). The percent of protected national land area is about 5.1%
Conservation within land use often begins with the following:
1. Identify and protect rare lands: Sensitive habitat like wetlands or coasts, or habitat with endangered plants and animals.
2. Protect large, contiguous critical habitats to avoid fragmentation.
3. Minimize the introduction and spread of non-native species
4. Avoid ecological disturbance when planning land use. For example, strategically build roads away from wild areas.
5. Incorporate natural and wild areas into land use planning. For example, build urban gardens or a small preserve.
Restoration includes building erosion controls to keep soil in place, such as:
- Grassed waterways
- Water and sediment control basins
- Filter strips
- Riparian buffers
- Terracing and contouring
- Drainage tiles
Protection and conserving land also requires considering the benefits and disadvantages to local people groups. When setting aside protected land, conflicts often arise between environmentalists and those who live off the land such as hunters, loggers, fishermen, miners, and tourism operators. Because of such conflicts, along with changing policies and budget cuts, protected lands require intensive management.
The Shinyanga region of Tanzania, once known as a desert, has been undergoing land use changes by a government program called HASHI. Tanzanians had cut down the abundant woodland to eradicate the disease carrying tsetse fly and later to clear land for crops. Because of clearing and low rainfall, Tanzanians couldn’t support their growing population as soil began degrading. Grasses, fruit, and medicinal plants also grew scarce in this poor region, whose people depended on livestock and crops. Large scale efforts in the 1970s failing to involve villagers did little to help the Shinyanga region.
In 1986, the president Nyerere tried a new community based program, resulting in successful soil conservation. The HASHI resulted in re-growth of acacia and miombo trees. Food crops are allowed, but in small patches with strict soil conservation measures. The HASHI program is successful because of local agro-pastoralists who have years of ecological knowledge. The successful statistics are listed below.
- 250,000 hectares of enclosed, restored land
- Protected land in 833 villages
- Higher household incomes, better diets, and greater livelihood for Tanzanians
- Greater biodiversity in trees, shrubs, grasses, herbs, birds, and mammals