Unit 5 Flashcards
Tragedy of the commons
the theory that individuals will use shared resources in their own self-interest, therefor degrading them.
ex. overgrazing, overfishing, overuse of ground water
Externalities
negative costs associated with human actions. (side effects due to tragedy of the commons)
Effects of Clear Cutting
Soil erosion
Increased soil and stream temperature
flooding and landslides
why does stream temp. increase as an effect of clear cutting?
loss of shade from trees increases the temperature of rivers and streams
Effects of tree plantations
lower biodiversity-mature, diverse forests are replaced by all the same species.
All trees are the same age-All trees are planted at the same time so there are no old dead trees for woodpeckers, insects or decomposers.
Consequences of Deforestation
-Reduces air filtering and carbon storing services
-releases CO2 into the atmosphere
Slash and Burn
a method of clearing land for agriculture by cutting trees and burning them (releases GHG into the atmosphere, but returns nutrients to the soil)
-Increases particulate matter in air which leads to respiratory issues
Green Revolution
a shift in agriculture away from small family farms to large industrial agriculture
-increased mechanization
-increased efficiency of land (high yeild)
Benefits and downsides of mechanization
benefit: increased yield and profit
Drawback: increased reliance on fossil fuels (released GHG) and heavy machinery compacts soil
High Yield Variety Crops
genetically modified crops that increased yield and food stability in regions where there was famine.
GMOs benefits and drawbacks
Benefits: have genes that allow them to grow faster, survive drought, or be tolerant to pests
Drawbacks: crops are all genetically identical. So genetic diversity is decreased, and crops are more receptable to disease.
Monocroping
growing one single species of crop
-very effective for harvest, but decreased biodiversity and increases soil erosion
Tilling
Mixing and breaking up soil to make planting easier
Drawbacks: increases erosion by loosening topsoil, loss of organic matter in topsoil over time, increased particulate matter in the air and turbidity in nearby streams
What are the drawbacks of synthetic fertilizers
-the do not increase the H2O holding capacity of the soil
-Nutrients may be leached and contaminate groundwater
-Fossil Fuels are used to produce synthetic fertilizers
Leaching
when water carries excess nutrients into groundwater or nearby surface water.
Furrow Irrigation
trenches dug along crops and filled with water (easy and inexpensive)
-66% efficiency
Flood Irrigation
entire field is flooded (easier, but may be disruptive to plants)
-80% efficiency
Drip Irrigation
Hoses are put on the ground and distribute water directly to plants roots.
-very efficient (95%), but very costly
Spray Irrigation
nozzles spray water onto crops
-very efficient, but very costly
Waterlogging
overwaters so the soil is fully saturated, and all of the pore space is filled with water so there is no air flow.
-can stunt growth or kill crops
Soil Salinization
when salt builds up in the soil overtime due to using ground water for irrigation (groundwater contains small amounts of salt that build up over time)
Why does soil salinization harm plants?
excess salt in the soil can dehydrate the plants roots and prevent them from absorbing enough water.
Soulutions to soil salinization
drip irrigation
soil aeriation
flushing with fresh water
How is water used by humans? (%)?
19% is used for industrial purposes
11% is used for Municipal purposes.
70% is used for agricultural purposes
Unconfined aquifers
Aquifers closer to the surface that are able to be replenished quicker
Confined aquifers
Aquifers with a layer of impermeable rock above them. They replenish much slower but are usually cleaner.
Bt Corn
Corn with a bacteria gene that produces its own pesticides.
-decreases insecticide use
Round Up Ready crops
crops that are genetically modified to be resistant to the herbicide round up
-increases herbicide use