Land & Water Use

Essential Knowledge for Unit 5

Topic #5.1: 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.

Adding more sheep results in more money for the individual sheepherder but everyone else who also uses the land is hurt.

Dinosaur Comics explains the tragedy of the commons

According to Business Insider, "American billionaires have made an average of $42 billion a week throughout the pandemic." Jeff Bezos of Amazon became the first person ever to amass $200 billion in wealth in August 2020. Meanwhile, Amazon employees make $15 per hour and many have been exposed to COVID-19. This is one of many economic examples of the tragedy of the commons.

Topic #5.2: Clearcutting

• 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.

A video about clearcutting from the Oregon timber industry

A video about clearcutting from members of the Cree First Nationa of Waswanipi

25 yrs

Weak trees removed

Clear cut

30 yrs

Years of growth

15 yrs

Seedlings planted

5 yrs

10 yrs

Clear-Cutting Forests

Advantages

Higher timber yields

Maximum profits in shortest time

Can reforest with fast-growing trees

Once old growth forest is cut down for harvesting timber, creating crop fields or building roads, it takes a very long time to restore. It can take many decades and possibly hundreds of years for a new forest to develop "old growth" characteristics. Meanwhile, habitat is "fragmented" or split up, decreasing biodiversity.

New highway

Old growth

Cleared plots

for agriculture

Highway

Cleared plots

for grazing

The Hiram College Biological Field Station contains the second largest uncut beech-maple forest in Ohio, but some of the stand was cleared for a development with expensive homes.

old growth forest

housing development

The Global Forest Change website shows the global loss in forest cover over the last 20 years as red dots.

Topic #5.3: The Green Revolution

• 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.

The Green Revolution

• Increases crop yields
• Monocultures of high-yield key crops
• Rice, wheat, and corn
• Large amounts of fertilizers, pesticides, water
• Multiple cropping
• Second Green Revolution
• Genetically modified organisms (GMOs)
• Fast growing dwarf varieties
• World grain has tripled in production

Continued expansion of farming areas, double-cropping existing farmland, and using seeds with superior genetics drove the Green Revolution in India.

Topic #5.4: Impacts of Agricultural Practices

• Agricultural practices that can cause environmental damage include tilling, slash- and-burn farming, and the use of fertilizers.

Agricultural practices are responsible for about half of the greenhouse gas emissions that are causing climate change.

Fertilizer runoff from farm fields adds nutrients to Lake Erie, which causes harmful algal blooms (HABs) that result in fish kills and contaminated drinking water.

Topic #5.5: Irrigation Methods (1/6)

• The largest human use of freshwater is for irrigation (70%).
• Types of irrigation include furrow irrigation, flood irrigation, spray irrigation, and drip 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.

Topic #5.5: Irrigation Methods (2/6)

• 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.

Topic #5.5: Irrigation Methods (3/6)

• 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.

Topic #5.5: Irrigation Methods (4/6)

• Spray irrigation involves pumping groundwater 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.

Topic #5.5: Irrigation Methods (5/6)

• 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.

Topic #5.5: Irrigation Methods (6/6)

• 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.

From the mini-series "Earth: A New Wild", host Dr. M. Sanjayan looks at the impacts of irrigation on the Colorado river in the United States and Mexico (start at 31:09)

Topic #5.6: Pest Control Methods

• 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.
• 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.

From the mini-series "America Revealed: Food Machine", host Yul Kwon looks at farmers use GMOs and pesticides to fight destructive pests (start at 31:48)

From the mini-series "America Revealed: Food Machine", host Yul Kwon looks at how pesticides are impacting pollinators such as bees and other insects (start at 38:51)

Topic #5.7: Meat Production Methods (1/4)

• Methods of meat production include concentrated animal feeding operations (CAFOs), also called feedlots, and free-range grazing.

Topic #5.7: Meat Production Methods (2/4)

• 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 operations (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.

Topic #5.7: Meat Production Methods (3/4)

• 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.

Topic #5.7: Meat Production Methods (4/4)

• Less consumption of meat could reduce CO₂, methane, and N₂O emissions; conserve water; reduce the use of antibiotics and growth hormones; and improve topsoil.

From the mini-series "America Revealed: Food Machine", host Yul Kwon looks at how cows are raised in CAFOs to decrease the cost of beef (start at 21:03)

Topic #5.8: Impacts of 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.

This map provides data from 1900 on predatory fish populations of such species as bluefin tuna and halibut in the North Atlantic.

By the year 2000, many of these predatory fish species had been wiped out by overfishing.

From the mini-series "Earth: A New Wild", host Dr. M. Sanjayan looks at the impacts of overfishing in Lake Malawi and how it's making people sick (start at 7:06)

Topic #5.9: Impacts of Mining (1/2)

• 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.

Coal mining techniques in Appalachia include underground mining and surface mining.

Removing mountaintops in order to get to the coal below can result in significantly altered landscapes.

Surface mining, including strip mining and mountaintop removal, causes signficant damage to local ecosystems and decreases biodiversity.

"Over five hundred mountains in West Virginia have been destroyed because of new mining techniques used by coal companies in the Appalachians."

Topic #5.9: Impacts of Mining (2/2)

• 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.

Mining wastes, also known as "tailings", can seep into surface water when rain dissolves the toxic heavy metals that are left behind by mining companies.

In 2015, a mistake by the EPA during an abandoned mine cleanup accidentally spilled 3 million gallons of contaminated water into Colorado's Animas River.

A common phrase from the mining industry is, "If it can't be grown, it has to be mined." As of 2020, there are over 330 million Americans. What is the cumulative impact of everyone needing these resources for modern life?

Topic #5.10: Impacts of Urbanization

• 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.

This map visualizes the history of urban settlements over 6,000 years.

This animation shows some of the numbers driving the rapid growth of cities in China.

More impervious surface results in more runoff and less infiltration by precipitation; in other words, less rain soaks into the ground and instead ends up in surface water.

As people move out of crowded cities into suburbs, urban sprawl not only disturbs local ecosystems but also results in greater fossil fuel emissions as people have to drive farther to go to work, school, and shopping centers

Most of global population growth is happening in urban areas, a trend that is projected to continue for decades.

An example of urban sprawl: Las Vegas, 1984

An example of urban sprawl: Las Vegas, 1999

An example of urban sprawl: Las Vegas, 2009

Topic #5.11: Ecological Footprints

• Ecological footprints compare resource demands and waste production required for an individual or a society.

When thinking of an ecological footprint, imagine the damage done when a big boot steps on a flowerbed. The bigger the boot, the greater the damage.

According to the World Wildlife Fund, the average American uses 7.19 global hectares (gha) of resources each year, which is #5 largest in the world. The average human footprint is 2.8 gha per person, while Earth's biocapacity is only 1.7 gha per person.

A hectare is an area 100 meters long by 100 meters wide (10,000 m²), which is similar to the size of the entire grassy area inside the track of Roosevelt Stadium.

Since around 1970, human activities have exceeded the planet's ability to generate new resources and repair damage. This is known as "Earth overshoot". Each year, we use resources as if we have 1.7 Earths, but we only have one.

Topic #5.12: Introduction to 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.

Sustainability is a complex topic that involves the environment, the economy, and society. How can humans live in a way that works for everyone, forever?

These are some examples of possible sustainable cities. What would sustainable living look like? How much effort will it take? How much will it cost? Will we like it?

Topic #5.13: Methods to Reduce 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.

The Cleveland Tree Plan is a $60 million effort to double the city's tree canopy by 2040 so that it can improve life in Cleveland in multiple ways, including reducing stormwater runoff and combined sewer overflow (which is illegal).

Topic #5.14: 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.
• 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.

Topic #5.15: Sustainable Agriculture

• 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.

Topic #5.16: 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.

Topic #5.17: Sustainable Forestry

• 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.

A wide variety of industries contribute to deforestation.

A typical sustainable forest will contain trees of all ages and often different species of trees. As the trees mature they are felled and the wood is processed at saw mills. Felled trees are replaced with seedlings so that the forest is constantly renewed. It can also provide jobs for the tourist industry.