Unit 5: Land and Water Use

Explain the concept of the tragedy of the commons.

• The tragedy of the commons suggests that individuals will use shared resources in their own self-interest rather than in keeping with the common good, thereby depleting the resources.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe the effect of clearcutting on forests.

• Clearcutting can be economically advantageous but leads to soil erosion, increased soil and stream temperatures, and flooding.
• Forests contain trees that absorb pollutants and store carbon dioxide. The cutting and burning of trees releases carbon dioxide and contributes to climate change.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe changes in agricultural practices.

• The Green Revolution started a shift to new agricultural strategies and practices in order to increase food production, with both positive and negative results. Some of these strategies and methods are mechanization, genetically modified organisms (GMOs), fertilization, irrigation, and the use of pesticides.
• Mechanization of farming can increase profits and efficiency for farms. It can also increase reliance on fossil fuels.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe agricultural practices that cause environmental damage.

• Agricultural practices that can cause environmental damage include tilling, slash-and-burn farming, and the use of fertilizers.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe different methods of irrigation.

• The largest human use of freshwater is for irrigation (70%).
• Types of irrigation include drip irrigation, flood irrigation, furrow irrigation, drip irrigation, and spray irrigation.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe the benefits and drawbacks of different methods of irrigation.

• Waterlogging occurs when too much water is left to sit in the soil, which raises the water table of groundwater and inhibits plants’ ability to absorb oxygen through their roots.
• Furrow irrigation involves cutting furrows between crop rows and filling them with water. This system is inexpensive, but about 1/3 of the water is lost to evaporation and runoff.
• Flood irrigation involves flooding an agricultural field with water. This system sees about 20% of the water lost to evaporation and runoff. This can also lead to waterlogging of the soil.
• Spray irrigation involves pumping ground water into spray nozzles across an agricultural field. This system is more efficient than flood and furrow irrigation, with only 1/4 or less of the water lost to evaporation or runoff. However, spray systems are more expensive than flood and furrow irrigation, and also requires energy to run.
• Drip irrigation uses perforated hoses to release small amounts of water to plant roots. This system is the most efficient, with only about 5% of water lost to evaporation and runoff. However, this system is expensive and so is not often used.
• Salinization occurs when the salts in groundwater remain in the soil after the water evaporates. Over time, salinization can make soil toxic to plants.
• Aquifers can be severely depleted if overused for agricultural irrigation, as has happened to the Ogallala Aquifer in the central United States.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe the benefits and drawbacks of different methods of pest control.

• One consequence of using common pest-control methods such as pesticides, herbicides, fungicides, rodenticides, and insecticides is that organisms can become resistant to them through artificial selection. Pest control decreases crop damage by pest and increases crop yields.
• Crops can be genetically engineered to increase their resistance to pests and diseases. However, using genetically engineered crops in planting or other ways can lead to loss of genetic diversity of that particular crop.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Identify different methods of meat production.

• Methods of meat production include concentrated animal feeding operations (CAFOs), also called feedlots, and free-range grazing.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe the benefits and drawbacks of different methods of meat production.

• Meat production is less efficient than agriculture; it takes approximately 20 times more land to produce the same amount of calories from meat as from plants.
• Concentrated animal feeding operation (CAFOs) are used as a way to quickly get livestock ready for slaughter. They tend to be crowded, and animals are fed grains or feed that are not as suitable as grass. Additionally, feedlots generate a large amount of organic waste, which can contaminate ground and surface water. The use of feedlots are less expensive than other methods, which can keep costs to consumers down.
• Free range grazing allows animals to graze on grass during their entire lifecycle. Meat from free range animals tends to be free from antibiotics and other chemicals used in feedlots. Organic waste from these animals acts as fertilizer. Free range grazing requires large areas of land and the meat produced is more expensive for consumers.
• Overgrazing occurs when too many animals feed on a particular area of land. Overgrazing causes loss of vegetation, which leads to soil erosion.
• Overgrazing can cause desertification. Desertification is the degradation of low precipitation regions toward being increasingly arid until they become deserts.
• Less consumption of meat could reduce CO₂, methane, and N₂O emissions; conserve water; reduce the use of antibiotics and growth hormones; and improve topsoil.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe causes of and problems related to overfishing.

• Overfishing has led to the extreme scarcity of some fish species, which can lessen biodiversity in aquatic systems and harm people who depend on fishing for food and commerce.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe natural resource extraction through mining.

• As the more accessible ores are mined to depletion, mining operations are forced to access lower grade ores. Accessing these ores requires increased use of resources that can cause increased waste and pollution.
• Surface mining is the removal of large portions of soil and rock, called overburden, in order to access the ore underneath. An example is strip mining, which removes the vegetation from an area, making the area more susceptible to erosion.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe ecological and economic impacts of natural resource extraction through mining.

• Mining wastes include the soil and rocks that are moved to gain access to the ore and the waste, called slag and tailings that remain when the minerals have been removed from the ore. Mining helps to provide low cost energy and material necessary to make products. The mining of coal can destroy habitats, contaminate ground water, and release dust particles and methane.
• As coal reserves get smaller, due to a lack of easily accessible reserves, it becomes necessary to access coal through subsurface mining, which is very expensive.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Describe the effects of urbanization on the environment.

• Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle.
• Urbanization, through the burning of fossil fuels and landfills, affects the carbon cycle by increasing the amount of carbon dioxide in the atmosphere.
• Impervious surfaces are human-made structures—such as roads, buildings, sidewalks, and parking lots—that do not allow water to reach the soil, leading to flooding.
• Urban sprawl is the change in population distribution from high population density areas to low density suburbs that spread into rural lands, leading to potential environmental problems.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Explain the variables measured in an ecological footprint.

• Ecological footprints compare resource demands and waste production required for an individual or a society.
• Enduring understanding EIN-2: When humans use natural resources, they alter natural systems.

Explain the concept of sustainability.

• Sustainability refers to humans living on Earth and their use of resources without depletion of the resources for future generations. Environmental indicators that can guide humans to sustainability include biological diversity, food production, average global surface temperatures and CO₂ concentrations, human population, and resource depletion.
• Sustainable yield is the amount of a renewable resource that can be taken without reducing the available supply.
• Enduring understanding STB-1: Humans can mitigate their impact on land and water resources through sustainable use.

Describe methods for mitigating problems related to urban runoff.

• Methods to increase water infiltration include replacing traditional pavement with permeable pavement, planting trees, increased use of public transportation, and building up, not out.
• Enduring understanding STB-1: Humans can mitigate their impact on land and water resources through sustainable use.

Describe integrated pest management.

• Integrated pest management (IPM) is a combination of methods used to effectively control pest species while minimizing the disruption to the environment. These methods include biological, physical, and limited chemical methods such as biocontrol, intercropping, crop rotation, and natural predators of the pests.
• Enduring understanding STB-1: Humans can mitigate their impact on land and water resources through sustainable use.

Describe the benefits and drawbacks of integrated pest management (IPM).

• The use of integrated pest management (IPM) reduces the risk that pesticides pose to wildlife, water supplies, and human health.
• Integrated pest management (IPM) minimizes disruptions to the environment and threats to human health but can be complex and expensive.
• Enduring understanding STB-1: Humans can mitigate their impact on land and water resources through sustainable use.

Describe sustainable agricultural and food production practices.

• The goal of soil conservation is to prevent soil erosion. Different methods of soil conservation include contour plowing, windbreaks, perennial crops, terracing, no-till agriculture, and strip cropping.
• Strategies to improve soil fertility include crop rotation and the addition of green manure and limestone.
• Rotational grazing is the regular rotation of livestock between different pastures in order to avoid overgrazing in a particular area.
• Enduring understanding STB-1: Humans can mitigate their impact on land and water resources through sustainable use.

Describe the benefits and drawbacks of aquaculture.

• Aquaculture has expanded because it is highly efficient, requires only small areas of water, and requires little fuel.
• Aquaculture can contaminate wastewater, and fish that escape may compete or breed with wild fish. The density of fish in aquaculture can lead to increases in disease incidences, which can be transmitted to wild fish.
• Enduring understanding STB-1: Humans can mitigate their impact on land and water resources through sustainable use.

Describe methods for mitigating human impact on forests.

• Some of the methods for mitigating deforestation include reforestation, using and buying wood harvested by ecologically sustainable forestry techniques, and reusing wood.
• Methods to protect forests from pathogens and insects include integrated pest management (IPM) and the removal of affected trees.
• Prescribed burn is a method by which forests are set on fire under controlled conditions in order to reduce the occurrence of natural fires.
• Enduring understanding STB-1: Humans can mitigate their impact on land and water resources through sustainable use.