Unit 5 · Land and Water Use

Tragedy of the commons ● (core concept) — 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.

Clearcutting effects ● (core concept) — Clearcutting can be economically advantageous but leads to soil erosion, increased soil and stream temperatures, and flooding.

Forests and carbon storage ● (core concept) — Forests contain trees that absorb pollutants and store carbon dioxide. The cutting and burning of trees releases carbon dioxide and contributes to climate change.

Green Revolution ● (core concept) — The Green Revolution started a shift to new agricultural strategies and practices in order to increase food production, with both positive and negative results. Strategies included mechanization, genetically modified organisms (GMOs), fertilization, irrigation, and the use of pesticides.

Mechanization of farming ● (core concept) — Mechanization of farming can increase profits and efficiency for farms, but it can also increase reliance on fossil fuels.

Environmentally damaging agricultural practices ● (core concept) — Agricultural practices that can cause environmental damage include tilling, slash-and-burn farming, and the use of fertilizers.

Agricultural water use ● (core concept) — On a global scale, approximately 70% of human freshwater consumption is used for agriculture.

Irrigation methods ● (core concept) — Types of irrigation include drip irrigation, flood irrigation, furrow irrigation, and spray irrigation.

Waterlogging ● (core concept) — 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 ● (core concept) — 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 ● (core concept) — Flood irrigation involves flooding an agricultural field with water. About 20% of the water is lost to evaporation and runoff, and it can also lead to waterlogging of the soil.

Spray irrigation ● (core concept) — Spray irrigation involves pumping groundwater into spray nozzles across an agricultural field. It is more efficient than flood and furrow irrigation, with only 1/4 or less of the water lost to evaporation or runoff, but it is more expensive and requires energy to run.

Drip irrigation ● (core concept) — Drip irrigation uses perforated hoses to release small amounts of water to plant roots. It is the most efficient method, with only about 5% of water lost to evaporation and runoff, but it is expensive and so is not often used.

Salinization ● (core concept) — Salinization occurs when the salts in groundwater remain in the soil after the water evaporates. Over time, salinization can make soil toxic to plants.

Aquifer depletion (Ogallala) ● (core concept) — Aquifers can be severely depleted if overused for agricultural irrigation, as has happened to the Ogallala Aquifer in the central United States.

Pesticide resistance ● (core concept) — 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 pests and increases crop yields.

Genetically engineered crops ● (core concept) — Crops can be genetically engineered to increase their resistance to pests and diseases. However, using genetically engineered crops can lead to loss of genetic diversity of that particular crop.

Meat production methods ● (core concept) — Methods of meat production include feedlots and concentrated animal feeding operations (CAFOs), as well as pasture-based systems such as rotational grazing and free-range grazing.

Meat vs. plant-based environmental impacts ● (core concept) — Meat production requires more land, water, and energy per gram of protein produced than the production of plant-based foods, and it increases nutrient pollution and emissions of greenhouse gases such as methane. The environmental impacts vary by the type of livestock raised and production practices used.

CAFOs ● (core concept) — Concentrated animal feeding operations (CAFOs) can be more economically efficient, which lowers costs for consumers. Animals raised in CAFOs are kept in confined spaces and fed grain- and soy-based diets. CAFOs have high concentrations of manure that can contaminate nearby waterways if not properly managed, and routine use of antibiotics in CAFOs can contribute to the global risks of antibiotic resistance.

Free-range and pasture-based grazing ● (core concept) — Free-range or pasture-based grazing systems allow animals to feed on grass or forage for most of their lives. Rotational grazing can improve the sustainability of these systems. Manure delivers nutrients to pasture soils, but runoff and erosion risks remain if animal density is high. These systems require more land, leading to higher consumer costs, and not all free-range systems are antibiotic-free.

Overgrazing ● (core concept) — Overgrazing occurs when the livestock population exceeds the land's capacity to regenerate vegetation. This results in reduced plant cover, soil erosion, and soil compaction, all of which reduce soil fertility. Overgrazing also reduces biodiversity and lowers carbon storage. Rotational grazing can help prevent or minimize these impacts.

Desertification ● (core concept) — Overgrazing can lead to desertification in arid and semi-arid regions. Implementing restoration efforts, soil conservation measures, and improved grazing practices can help slow or reverse the desertification process.

Reducing meat consumption ● (core concept) — Less consumption of meat, especially from ruminant livestock such as cattle and sheep, can lower emissions of CO2, CH4, and N2O, conserve freshwater resources, and reduce reliance on antibiotics and growth hormones. Advances in feed quality and precision farming technologies can also mitigate environmental impacts.

Overfishing ● (core concept) — 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.

Lower-grade ores ● (core concept) — 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 (strip mining) ● (core concept) — 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.

Mining wastes and impacts ● (core concept) — Mining wastes include the soil and rocks moved to gain access to the ore (overburden) and the waste, called slag and tailings, that remain when the minerals have been removed from the ore. Mining provides low-cost energy and materials for products, but coal mining can destroy habitats, contaminate groundwater, and release dust particles and methane.

Subsurface mining ● (core concept) — 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.

Urbanization and resource depletion ● (core concept) — Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle.

Urbanization and the carbon cycle ● (core concept) — 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 ● (core concept) — 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 ● (core concept) — 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.

Ecological footprint ● (core concept) — Ecological footprints compare resource demands and waste production required for an individual or a society.

Sustainability ● (core concept) — 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 ● (core concept) — Sustainable yield is the amount of a renewable resource that can be taken without reducing the available supply.

Methods to reduce urban runoff ● (core concept) — Methods to increase water infiltration and reduce urban runoff include replacing traditional pavement with permeable pavement, planting trees, increased use of public transportation, and building up, not out.

Integrated pest management (IPM) ● (core concept) — 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.

Benefits of IPM ● (core concept) — The use of integrated pest management (IPM) reduces the risk that pesticides pose to wildlife, water supplies, and human health.

Drawbacks of IPM ● (core concept) — Integrated pest management (IPM) minimizes disruptions to the environment and threats to human health but can be complex and expensive.

Soil conservation methods ● (core concept) — 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.

Improving soil fertility ● (core concept) — Strategies to improve soil fertility include crop rotation and the addition of green manure and limestone.

Rotational grazing ● (core concept) — Rotational grazing is the regular rotation of livestock between different pastures in order to avoid overgrazing in a particular area.

Benefits of aquaculture ● (core concept) — Aquaculture has expanded because it is highly efficient, requires only small areas of water, and requires little fuel.

Drawbacks of aquaculture ● (core concept) — 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.

Mitigating deforestation ● (core concept) — Some of the methods for mitigating deforestation include reforestation, using and buying wood harvested by ecologically sustainable forestry techniques, and reusing wood.

Protecting forests from pests ● (core concept) — Methods to protect forests from pathogens and insects include integrated pest management (IPM) and the removal of affected trees.

Prescribed burn ● (core concept) — Prescribed burn is a method by which forests are set on fire under controlled conditions in order to reduce the occurrence of natural fires.