Unit 5 - Land and Water Use Flashcards
tragedy of the commons
- when individuals use shared/public resources in their own self interests degrading them
- must be a public resource (not privately owned)
examples of tragedy of the commons
overgrazing, overfishing, water and air pollution, overuse of groundwater
why does tragedy of commons occur
- when no one owns the resource, no one directly suffers
- people assume others will overuse it if they dont
- no penalty for overusing
externalities
negative costs associated with human actions that aren’t accounted for in the price (unintended side-effects)
overfishing
can lead to fishery collapse (population crash), loss of income and starvation
pesticide runoff
from farms contaminates drinking water
how to solve TOC
- private land ownership
- fees or taxes for use
- taxes, fines, criminal charges for pollution of shared soil, air, water resources
clearcutting
practice in which most or all trees in an area are uniformly cut down
direct effects of clear cutting
- soil erosion
- increased soil and stream temp
- flooding an landslides
what replaces clear-cuts
tree plantations
effects of tree plantations
- lowers biodiversity
- all the same age (lowers biodiversity more)
slash and burn
method of clearing land for agriculture by cutting trees and burning them releases CO2, N2O, and water vapor into the atm.
- return nutrients in plants to soil
green revolution when and where
- 1950s to late 1960s
- where: worldwide but major impact on developing countries like Mexico and India
what was the green revolution
a shift in agriculture away from small family operated farms to large industrial scale agribusiness
- increase in productivity due to higher yield crops that were pest and disease resistant
- increased use of mechanization, GMOS, irrigation, fertilizers,
- short term profitability
consequences of green revolution
soil erosion, loss of biodiversity, ground surface water contamination, requires massive input of water
mechanization
introduction of machinery
mechanization: pros
increased use of tractors for plowing and tilling fields = increased yield and profits
mechanization: cons
- increased reliance in fossil fuels
- emits GHGs
- heavy machines compact soil. decrease water holding capacity
high yield variety crops
- hybrid or genetically modified crops that produce a higher yield (amt of crop produced per unit of area)
GMOs
genetically modified crops that have genes for drought tolerance, pest resistance, faster growth, larger
GMOs: pros
increases profitability with fewer plants lost to drought, disease, or pests; larger plant size
GMOs: cons
crops are genetically identical so genetic diversity is decreased and susceptibility to diseases or pest is increased
synthetic fertilizer
shift from organic fertilizer (like manure and compost) to man made NH4, nitrate, phosphate
synthetic fertilizer: pros
increased yields and profits with more key nutrients
irrigation
drawing water from the ground or nearby surface waters and distributing it on fields to increase plant growth
irrigation: pros
make ag. possible for parts of the world that are naturally too dry (dont receive enough rain)
irrigation: cons
- can deplete groundwater sources, esp. aquifiers
- overwatering can drown roots and cause soil salinization
example of pesticides harming nontarget species
- DOT thinned shells of bird eggs, especially eagles
- atrazine turns amphibians and fish intersex
monocropping
growing one single species (corn, wheat, soy) of crop
monocropping is highly efficient for
harvest, pesticide, and fertilizer application
negatives of monocropping
- greatly decreases biodiversity
- increases soil erosion (crops harvested all at once and soil left bare)
- decreases habitat diversity for species living in an area
tilling
mixing and breaking up soil to make planting easier; loosen soil for roots
negatives of tilling
- increases erosion by loosening topsoil, breaking up leftover root structure from harvest
- loss of organic matter and topsoil nutrients over time
- increases PM in air