*Unit 5 Flashcards
What is the tragedy of the commons?
The tragedy of the commons suggests that individuals will use shared resources in the own self-interest rather than in keeping with the common good, thereby depleting the resources.
How do you prevent the tragedy of the commons?
The tragedy of the commons can be avoided by regulating their usage, replenishing their supply, and ensuring compliance with these policies:
Regulating usage:
- Hunting/fishing licenses
- Land permits
- Country quotas (pollution, fish harvest, etc.)
- Selective cutting of trees
Replenishing supply:
- Replant trees
- Throw back fish full of eggs
- Rotate which grasslands are used for grazing
Ensuring compliance:
- Treaties
- Laws
- Oversight of treaties/laws:
- Fines
- Incentives - subsidies, debt forgiveness, etc.
What is “the commons”
“The commons” are areas used by everyone, yet owned by no one (the ocean, forests, grazing lands, etc.).
What is the role of forests in our ecosystems?
Forests…
- serve as a habitat
- aid in soil formation/retention
- moderate local climate
- serve as a food source
- remove air/water pollutants
- increase albedo of Earth
- serve a role in biogeochemical cycles
What are the economic benefits of forests?
Forests provide…
- grazing for livestock
- agricultural land for shade-tolerant plants
- ecotourism and aesthetic-related use
- impact on nearby real estate values
- a source of agricultural products
- a source of potential medicine
- a source of land for other uses - agriculture, mining, residences
What is clearcutting?
Clearcutting is when you cut down all the trees in a forest.
What are the impacts of clearcutting on terrestrial environments?
Impacts include…
- loss of biodiversity
- loss of habitat
- loss of recreational areas for humans
- loss of an aesthetic area
- loss of a food source
With no trees, there’s no leaves and biomass falling to decompose to form humus - the rich layer that’s on top of the topsoil. Desertification starts to appear as topsoil is blown away, exposing subsoil. Decreased albedo means less absorption of sunlight, causing the ground to heat up, which means releasing more water vapor from the soil, and thus anything attempting to grow has less nutrients, topsoil, and water.
What are the impacts of clearcutting on the carbon cycle?
Less trees means less photosynthesis and more carbon dioxide in the atmosphere. It also means that there are less carbon sinks, and therefore, more carbon dioxide in the air. Aerobic decomposition will release carbon dioxide and anaerobic decomposition releases nothing.
What are the impacts of clearcutting on aquatic environments?
Increased soil erosion means less infiltration of fresh water into groundwater sources that discharge into streams, lakes, oceans, and estuaries. In contrast, it does cause a lot of run-off. The water picks up soil, nutrients, and pollution and moves them across the ground. Oftentimes the run-off ends up in rivers.
What are the impacts of turbidity and soil run-off on aquatic environments?
Turbidity: The amount of suspended solids in water
- Increased turbidity results in decreased primary productivity because the solids block out the sunlight, which prevents photosynthesis.
- Increased turbidity also results in a decrease in albedo since it’s darker (due to less sunlight absorption), which heats the water up. Water holds less dissolved gases in warmer temperatures, so when heated, the dissolved oxygen levels in the water decrease, and populations begin to die out.
- Eutrophication
- Loss of habitat/biodiversity
When and what was The Green Revolution?
The Green Revolution (began in the 1940s but didn’t take hold till the 1960s) was a shift to new agricultural strategies and practices in order to increase food production, with both positive and negative results. It was a transition from small scale, individual-run organizations to large industrial corporations, that ran thousands of acres, and were mechanized, high productivity operations.
What are the downfalls of mechanization?
- Increased fossil fuel use
- Impurities released in the process of extraction
- Reliance on machines and the fossil fuels they need to operate
How do large industrial corporations differ from small scale corporations?
Large industrial corporations are very productive and mechanized. They use artificial fertilizer, pesticides, extensive irrigation, and GMOs.
What are the pros and cons of monoculture?
Pros:
- Easy to plant, easy to maintain, easy to harvest
- All plants need the same types of fertilizer
- All plants have the same pests
- All plants have the same watering schedule
Cons:
- Only growing one plant results in loss of limited genetic variability, habitat, biodiversity, and ancestral varieties.
remember that when you decrease genetic diversity, there’s an increased chance for a catastrophic event
What are the pros and cons of pesticides?
Pros:
- Easy to use
- Increase yield
- Increase profits
Cons:
- Pesticide treadmill
- Artificial selection of resistant pests
- Persistence in the environment
- Harm/kill non-target species
What are the pros and cons of GMOs?
Pros:
- Creates crops that can grow on unusable land for agriculture
- Can make crops herbicide resistant
- Can make crops produce their own insecticide
Cons:
- Semi-arid and arid lands converted to agriculture produce low-nutrient soil
- Weeds can become herbicide resistant with excess use of herbicide (ex. Roundup-ready crops)
- Bt crops may kill non-target species
- Bt crops may lead to insecticide resistant pests
- Moral/ethical/economic issues patented with genetic modification
- Reduction in genetic diversity
What are the environmental and economic advantages of genetic engineering?
Environmental:
- Higher yields per acre and hence less acreage needed/impacted by agriculture
- Permits low-tillage agriculture which reduces soil erosion, energy consumption associated with farm machinery, and evaporative water loss
- May have lower fertilizer requirements, insect resistance, drought resistance, disease resistance, salinity tolerance, frost resistance, perennial life spans, and firmer tissue
Economic:
- Permits low/reduced-tillage agriculture resulting in reduced soil erosion, energy consumption associated with farm machinery, water loss that lowers associated costs, reduced greenhouse gas emissions from agricultural activities and associated costs (carbon sequestration), and retention of soil nutrients
- Increased profits/reduced costs due to use of GM crops that have higher yields per acre, lower fertilizer/pesticide/herbicide requirements, insect resistance, disease resistance, healthier appearance, drought resistance, saline resistance, less worker exposure to fertilizer/pesticides/herbicides and lower associated health-care costs, increased nutritional value, pharmacological value, frost resistance - extends seasonal productivity, and firm tissue - less spoilage of crops in transit
- Decreased health-care costs dues to worker exposure to pesticides and better-nourished people
What are the environmental and economic disadvantages of genetic engineering?
Environmental:
- Low-tillage agriculture often depends on high dosage and frequent application of herbicides
- GM crops with: insect resistance may impact beneficial insects, drought-resistance gene may lead to agricultural use of currently marginal, semi-arid areas, leading to increased human pressures/loss of natural landscape, salinity-tolerance gene may lead to agricultural use of currently marginal, saline soils, leading to increased human pressures/loss of natural landscape, altered genes may impact human health with altered proteins and/or subsequent toxins
- Native plant diversity may be impacted by the spread of genes to non-engineered crops
- Higher yields per acre often require higher inputs and often lead to greater soil depletion and erosion
- GM crops are often engineered to have lower genetic variability than non-GM crops, thereby making GM crop monocultures more vulnerable to mass morality than non-GM crop monocultures exposed to disease or pest outbreaks or severe environmental changes
Economic:
- Higher yields per acre often lead to greater soil depletion, requiring higher costs of mitigation
- Low-tillage agriculture often depends on costly high dosage/frequent application of herbicides to control competitive weeds that are normally controlled by tillage
- Decreased profits/increased costs due to use of GM crops have increased fertilizer demand to reach yield potential, require investment in a new generation of pesticides because the GM crop has promoted target insect pest resistance, increase the amount and frequency of pesticide applications to mitigate non-target pests whose virulence increases, have patented and sterile seeds, and risk consumer rejection/import restrictions that result in lower demand for GM crops
Describe agricultural practices that cause environmental damage.
Tillage - Tilling is the process of preparing to plant seeds. However, this leaves the soil bare, which allows soil erosion and run-off to occur. If nutrient-rich soil ends up in a body of water, eutrophication can happen.
Slash and burn agriculture - This is a technique used in developing countries to add nutrients to soil (only works for a couple of years. A farmer will cut down trees in a rainforest, burn them, and use the ashes to amend “enrich” the soil. However, this process is extremely unsustainable as you will eventually end up with an area with no nutrients available that can no longer grow crops (ex. The US Dust Bowl in the 1930s). Additionally, carbon dioxide is released into the atmosphere as a result of the burning of the forests, which disrupts the carbon cycle.
Intensive agriculture - In intensive agriculture, a large number of a singular crop is grown for economic purposes, with limited genetic variation. As seen before, small genetic diversity results in an increased chance of a catastrophic event happening.
What are the pros and cons of synthetic fertilizer versus organic fertilizer?
Pros - Synthetic Fertilizer: Synthetic Fertilizer is easy to transport and use. It’s customizable and the exact levels of nutrient are known.
Cons - Synthetic Fertilizer: This type of fertilizer is very water soluble, so it can end up in streams and rivers, leading to eutrophication. It also does nothing to improve soil structure.
Pros - Organic Fertilizer: Organic Fertilizer can be used to structure soil and hold it in place to prevent run off.
Cons - Organic Fertilizer: The levels of nutrients within this type of fertilizer (ex. cow manure) are unknown. And, since you don’t know precisely what’s in it, it’s harder to use.
What is the process that allows nitrogen to be converted and used in plant growth?
The Haber-Bosch Process: 3H2 + N2 -> 2NH3
Describe the benefits and drawbacks of different methods of irrigation.
Flood Irrigation - In this type of irrigation, crops are planted by a body of water, and, like the name says, they are flooded. There needs to be a low wall to retain the water and the soil needs to be graded (tilted so that gravity forces the water to run down stream). It’s a very simple and inexpensive form of irrigation, but results in a lot of evaporation, which is relatively inefficient.
Furrow Irrigation - This type of irrigation is where furrows or trenches are built between crops. It’s another inexpensive form of irrigation, but is also inefficient due to evaporation. This is used for plants that have a hard time tolerating being partially underwater. Note that this method is not efficient in sandy soil as the water will seep into the sand before it reaches the end of the row.
Spray Irrigation - In spray irrigation, a nozzles are placed and then rotated in a circle above crops for watering purposes. It’s more efficient than flood and furrow irrigation, but still has a decent amount of evaporation. As it’s also more mechanized than flood or furrow irrigation, it’s also more expensive as well.
Drip Irrigation - This type of irrigation is the most expensive of all the types; however, it’s also the most effective. Pipes are placed at the roots of plants to “drip” water directly into the soil. Barely any freshwater is lost to evaporation. Note that unlike flood or furrow irrigation, in drip and spray irrigation, there cannot be much sedimentation in the water as it will clog up the nozzles.
What issues arise from different types of irrigation?
Waterlogging - Underground, plants have small air pockets around their roots for cellular respiration. However, if these crops are overwatered, the pockets are filled, the roots die, and thus the plants die. This can be resolved by letting crops dry out or by simply only using this technique for plants that prefer being partially underwater (ex. rice)
Salinization - When crops are watered, sometimes small particles of salt are left behind. When too much of this salt builds up, it can cause the area to dry out and the plants to die. This can be prevented by flushing out the salt with fresh water (although this depletes the limited fresh water supply)
Tragedy of the commons/Aquifers - Aquifers are areas of groundwater where you have a concentration of water that is recharged by infiltration from rain or from runoff. A major issue with this, however, is the tragedy of the commons. Take the Ogallala Aquifer, which runs from Nebraska to Texas, for example. Farmers keep drawing from the Aquifer faster than it can be replenished. Thus, it will eventually run out.
Saltwater Intrusion - The high pressure of freshwater in aquifers keeps the saltwater out. However, as freshwater is drawn out of the aquifer, the pressure decreases, allowing saltwater in, mixing with the freshwater, rendering the aquifer useless. The solution to this problem is to maintain the freshwater pressure in the aquifer by not depleting the limited resource.
What are the drawbacks of CAFOs?
- CAFOs (Concentrated Animal Feeding Operations) take up a large amount of space
- Animal waste (particularly cattle waste) releases methane emissions. Also, waste is high in nitrates and phosphates, so the effect of waste run-off in water is similar to that of soil run-off.
- Fecal coliforms are normally benign, but those of the E.coli variation can sometimes appear in human foods if not careful
- Antibiotics can drive artificial selection and antibiotic-resistant bacteria, and growth hormones just add outside chemicals to meat.
- If CAFOs are in a given area for a large span of time, soil compaction and soil erosion can occur.
