Studied by 8 people
the tragedy of the commons theory (TOC)
individuals will use shared or public resources in their own self interest, degrading them
since they don’t experience the negative consequences of doing so
must be a public resource
must be degraded
can help us understand complex issues (air and water pollution)
can help us understand simple issues (why public restrooms are dirty)
why TOC happens
when nobody owns the resource, nobody directly suffers the negative consequences of depleting, degrading, or overusing it
people assume others will overuse the resource if they don’t
there is no penalty for overusing, degrading, polluting many public resources
how to solve the TOC
private land ownership
fees or tax for use
legislation
clearcutting
cutting down all of the trees in a given area at once
usually harvest for lumber or to clear the land for other uses
efficient for clearing land and harvesting lumber
serious consequences
direct effects of clearcutting
soil erosion
increased soil and stream temperatures
flooding and landslides
soil erosion
caused by loss of stabilizing root structure
removes soil organic matter and nutrients from forest
deposits sediments in local streams
warms water and makes it more turbid (cloudy)
increased soil and stream temperatures
loss of tree shade increases soil temperature
soil has lower albedo than leaves of trees
loss of tree shade along rivers and streams warms them
erosion of sediments into river warms them
flooding and landslides
logging machinery compacts soil
increased sunlight dries out soil
loss of root structure = erosion of topsoil and O horizon
all these factors decrease the water holding capacity of soil, causing floods and landslides
tree plantations
areas where the same tree species are repeatedly planted, grown, and harvested. helps after clearcutting, but…
lower biodiversity
biodiverse, mature forests are replaced with single species forests
less species diversity = lower resilience
less habitat diversity for other organisms
all the same age
all trees planted at the same time
more intraspecific competition
lowers biodiversity further
no dead trees for woodpeckers, insects, or decomposers
forest benefits
filtering of air pollutants
removal and storage of carbon dioxide from the atmosphere
habitat for organisms
consequences of deforestation
reduces air filtering and carbon storing services
cutting trees down releases carbon dioxide from decomposition of leftover organic material
slash and burn method of clearing land for agriculture by cutting trees and burning them releases carbon dioxide, N2O, and water vapor into the atmosphere
the green revolution
shift in agriculture away from small, family farms to large, industrial agribusiness
increased use of mechanization, GMOs, irrigation, fertilizers, and pesticides
greatly increases efficiency of lands, short-term profitability, and food supply
decreased world hunger and increased earth’s carrying capacity for humans
brings negative consequences (soil erosion, biodiversity loss, ground and surface water contamination).
mechanization
increased use of tractors for plowing and tilling fields, and combines for harvesting = increased yield and profits
increases reliance on fossil fuels
heavy machinery also compacts soil, decreasing water holding capacity and exposing topsoil to erosion
high-yield variety (HYV) crops
hybrid or genetically modified crops that produce a higher yield
hybrid = cross-pollinating different species or parent plants with ideal traits
increased yield and food stability in regions previously prone to famine
GMOs = crops with new genes spliced into their genome
GMOs
genetically modified crops have genes for drought tolerance, pest resistance, faster growth, and larger fruit/grain
increases profitability with fewer plants lost to drought, disease, or pests + larger plant size + yield/acre
GMO crops are all genetically identical so genetic diversity is decreased and susceptibility to disease or pests is increased
synthetic fertilizer
shift from organic fertilizers to synthetic fertilizers
increases yield and profits with more key nutrients needed for plant growth added to the soil
excess nitrate and phosphate are washed off fields and into nearby waters where they cause eutrophication (algal blooms)
requires fossil fuels for production, releasing carbon dioxide
doesn’t return organic matter to the soil, has no decomposers, and no increased water-holding capacity
leaching: water carries excess nutrients into groundwater or surface water as runoff
contaminates groundwater for drinking
causes eutrophication
irrigation
drawing water from the ground or nearby surface waters and distributing it on fields to increase plant growth
make agriculture possible in many parts of the world that are naturally too dry
can deplete groundwater sources, especially aquifers
over watering can drown roots (no oxygen access) and cause soil salinization (increase salt level)
pesticides
increase in use of synthetic pesticides - chemicals sprayed on crops that kill weeds, insects, rodents, and other pests that eat or damage crops
increases yield and profits with fewer plants lost to pests
can wash off crops in runoff and kill or harm non-target species in local soils or waters (bees especially
monocropping
growing a single species of crop
highly efficient harvest
highly efficient for pesticide and fertilizer application
greatly decreases biodiversity
more prone to pests
increases soil erosion
crops harvested all at once and soil left bare
decreases the habitat diversity for species living in the area.
tilling
mixing and breaking up soil to make planting easier
also loosens soil for roots
increases erosion by loosening topsoil, breaking up leftover root structures from harvest
loss of organic matter and topsoil nutrients over time
increased PM in the air and sediments in nearby water
slash and burn
cutting down vegetation and burning it to clear land for agriculture and return nutrients in plants to soil
deforestation
loss of habitat, biodiversity, carbon dioxide sequestration, loss of air pollution filtration
releases CO2, CO, N2O - all greenhouse gases that lead to global warming
increases PM in air
lowers albedo, making the area warmer
eutrophication
excess nutrient richness in reservoirs
frequently due to surface runoff
causes dense growth of plant life and death of animal life from lack of oxygen in aquatic ecosystems
furrow irrigation
trench dug along crops and filled with water
easy and inexpensive
water seeps into soil slowly
66% efficient
33% lost to runoff and evaporation
flood irrigation
flood entire field
easier but more disruptive to plants
can waterlog the soil and drown plants
80% efficient
20% runoff/evaporation
spray irrigation
ground or surface water pumped into spray nozzles
more efficient (less water loss) than flood or furrow
25% evaporation/runoff
more expensive (requires energy for pumps and movement of sprinklers)
drip irrigation
most efficient
most costly
over 95% efficient
holes in hose allow water to slowly drip out
avoids waterlogging and conserves waters
waterlogging
overwatering can saturate the soil, filling all soil pore space with water
doesn’t allow air into pores, so roots cant take in the O2 they need
can stunt growth or kill crops
solution: drip irrigation or soil aeration - poking holes or cores in soil to allow air in and drain water through soil
soil salinization
salinization: salt building up in soil over time
groundwater naturally has small amounts of salt
used for irrigation
water evaporates and salt is left behind in soil
over time, it can:
reach toxic levels
dehydrate plant roots
prevent plant growth
solution: drip irrigation, soil aeration, flushing with fresh water, switch to freshwater source
global human water use
industrial
power plants
metal/plastic manufacturing
municipal
households
agriculture
water for livestock
irrigation for crops
aquifer
a useable groundwater deposit for humans
replenished by groundwater recharge: rain water percolating down through soil into aquifer
unconfined aquifers recharge quickly
confined (layer of impermeable rock above and beneath) aquifers recharge slowly
longer-term water deposits
groundwater
H2O stored in pore space of permeable rock and sediment layers
depletion of aquifers
saltwater intrusion
excessive pumping near the coast lowers water table pressure, allowing saltwater to seep into groundwater
cone of depression
forms when the water table is lowered by excessive pumping, depleting water, and drying nearby wells.
pesticides
chemicals that are toxic to pests
rodenticides
fungicides
insecticides
herbicides
can cause genetically diverse pests to become resistant to pesticides with overuse through artificial selection
GMOs and pesticide use
roundup ready crops have increased herbicide use since crops cant be harmed by it
GMOs and genetic diversity
GM crops are generally identical/clones
no genetic diversity in the population
if there is disease or pest that affects the GM crops…
theyre all vulnerable
no opportunity for genetic mutation providing an adaptive trait
quick spreading
higher impact
CAFOs
also called feedlots: densely crowded method where animals are fed grain to raise them as quickly as possible
maximizes land use and profit
minimizes meat cost for consumers
given antibiotics and growth hormones to prevent disease outbreak and speed up meat production
animals produce a large volume of waste which can contaminate nearby surface or groundwater
produces large amounts of CO2, CH4 (methane), and N2O (greenhouse gasses → climate change)
manure lagoons
large, open storage pits for animal waste
waste contains: ammonia (N), hormones, antibiotics, fecal coliform bacteria (e. coli)
heavy rain can flood lagoons and contaminate nearby surface and ground water with runoff
denitrification of ammonia in manure produces N2O (extremely powerful GFG)
can be emptied and buried in landfills or turned into fertilizer pellets
free range grazing
animals (usually cows) graze on grass and grow at a natural rate without growth hormones
no need for antibiotics with dispersed population
doesn’t require production of corn to feed animals
waste is dispersed over land naturally, acting as fertilizer instead of building up in lagoons
requires more total land use per pound of meat produced
more expensive to the consumer
animals can graze on land too dry for most crop growth
overgrazing
too many animals grazing an area of land can remove all the vegetation
leads to topsoil erosion
animals also compact soil
decreases water holding capacity and causes more erosion
desertification: a process where fertile land becomes desert. usually due to drought, deforestation, or poor agriculture practices.
can occur if plants are killed by overgrazing and soil is compacted too much to hold water
rotational grazing
can prevent overgrazing and increase grass growth by distribution of manure.
inefficiency of meat
producing meat for humans to eat is far less efficient than producing plants in terms of energy, land, and water use
energy use: all the energy needed to plant, grow, and harvest crops to feed to animals + energy needed to:
bring water to animals
house animals
slaughter and package
land use: all the energy needed to grow crops + the space animals take up
water use: all water needed for crops + what animals drink
fisheries
populations of fish used for commercial fishing
fishery collapse
when overfishing causes 90% population decline in a fishery
population may never recover from fishery collapse due to decreased biodiversity, inability to find mates, inbreeding depression.
bottom trawling
an especially harmful fishing method that involves dragging a fishing net along the ocean floor
bycatch: unintended species like dolphins, whales, and turtles caught in nets
stirs up ocean sediment (turbidity) and destroys coral reef structure
decreases biodiversity by killing non-target species and removing coral reef habitat
fishing down the food web and trophic cascade
as we deplete large, predatory fisheries, we move down to smaller fish species
depletion of smaller fish populations: limits fishery recovery. decreases food supply of marine mammals and seabirds
ore
commercially valuable deposits of concentrated minerals that can be harvested and used as raw materials
metals
elements that conduct electricity, heat, and have structural properties for building
found within ores
reserve
the known amount of a resource left that can be mined
usually measured in years left of extraction
overburden
soil, vegetation, and rocks that are removed to get an ore deposit below
tailings and slag
leftover waste material separated from the valuable metal or mineral within ore
often stored in ponds at mine site
surface mining
the removal of overburden to access ore near surface. many types:
open pit
strip
mountaintop removal
placer
negative effects:
removal of vegetation and soil
topsoil erosion
habitat loss
turbidity increase in streams
increase PM in air
overburden
the material that lies above an area that lends itself to economic exploitation
like the rock, soil, and ecosystem lying above a coal/ore body
mountaintop removal
especially damaging to landscape, habitats, and streams nearby
subsurface mining
more expensive due to higher insurance and healthcare costs for workers
risks: poor ventilation leading to toxic gas exposure, mine shaft collapse, injury from falling rock, lung cancer, asbestos, fires, explosions
vertical shafts drilled down into ground
elevator to transport workers and resources
often used for coal
increasingly used as surface coal deposits are depleted
environmental impacts of mining
rainwater carries sulfuric acid into nearby streams or infiltrates ground water
lowers water pH, making toxic metals like mercury and aluminum more soluble and killing aquatic organisms
methane release (coal mining releases methane gas from rock around coal
vented out of mine to prevent explosion and continues seeping out after mine closes
PM release (coal mining releases a of of soot and particulates that irritate lungs)
acid mine drainage
rainwater leaks into abandoned mine tunnels and mixes with pyrite, forming sulfuric acid
mine reclamation
the process of restoring land to original state after mining has finished. includes:
filling of empty mine shafts/holes
restoring original contours of land
returning topsoil with acids, metals, and tailings removed
replanting of native plants
urbanization
the removal of vegetation to convert a natural landscape to a city (urban)
replaces soil, vegetation, and wetlands with impervious surfaces that don’t allow water to infiltrate into the ground
urbanization prevents groundwater recharge, causing precipitation to run into local bodies of water
natural stormwater damage
stormwater infiltrates into the ground
plants and trees work to absorb stormwater
urban stormwater damage
water hits impervious surface and runs off roofs, streets, parking lots, etc.
runoff goes into the sewers
urbanization carbon dioxide emissions
cement production
construction machinery
deforestation
landfills needed for disposing trash from large population
urbanization in coastal cities
population growth in coastal cities can lead to saltwater intrusion due to:
excessive groundwater withdrawal near coast, lowering water table pressure, allowing saltwater to seep into groundwater
sea level rise due to warming of ocean (thermal expansion) and melting of ice caps (increasing ocean volume) can contaminate fresh groundwater with salt
trends in population
people move from rural to urban areas for jobs, entertainment, cultural attractions
urban areas are more densely populated, minimizing driving and land use per person (decreases environmental impact per person)
highest growth is currently in suburban population
urban sprawl
population movement out of dense, urban centers to less dense suburban areas surrounding the city
refers to unplanned, poorly planned, or excessive spreading of urban areas
urban sprawl causes
cheaper property in suburbs than in cities (larger home for same price)
cars make it easy to still get from the suburbs into the city for work, entertainment, and cultural attractions
domino effect (neighbors leave so you leave)
fewer residents in cities leads to decline in tax revenue for city (decrease in city services)
residents leave so businesses follow
abandoned homes and businesses create blight (unsightly, rundown infrastructure) so more people leave
expanded highway system makes travel easier and increases driving
increase in driving increases fuel tax revenue, which is used to build more highways
highway expansion makes it easier to commute from suburbs into urban areas.
urban sprawl solutions
urban growth boundaries: zoning laws set by cities preventing development beyond a certain boundary
public transport and walkable city design that attracts residents to stay
mixed land use: residential, business, and entertainment buildings all located in the same area of a city
urban development
highway systems and urban sprawl disrupt natural ecosystems
ex: suburban neighborhoods or highways dividing habitats
solutions:
wildlife corridors and wildlife crossings
highway fencing
enforced anti-littering laws
encourage carpooling
urban growth
often reduces productive agricultural land near the city
solutions:
rooftop gardens
vertical farming
zoning for micro-livestock, bees, chickens, etc.
incentivize the development of unused land like under power lines for community gardens and green spaces
ecological footprint
measure pf how much a person/group consumes, expressed in an area of land. some factors (land required for) are:
food production
raw materials
housing
electricity production
disposing waste produced
carbon footprint
measured in tonnes of carbon dioxide produced by year, a measure of carbon dioxide released from an individual or groups consumption and activities
material goods
food production
energy use
factors that increase footprint
affluence increases carbon and ecological footprint
larger houses
more travel (gas)
more resources are needed for material goods
meat consumption
fossil fuel usage
factors that decrease footprint
renewable energy use
pubic transportation
plant-based diet
less consumption, less travel, less energy use
sustainability
consuming a resource or using a space in a way that does not deplete or degrade it for future generations
maximum sustainable yield
the maximum amount of a renewable resource that can be harvested without reducing or depleting the resource for future use
roughly half carrying capacity
maximizes yield and regeneration rate of the population
see in previous unit as cultural carrying capacity
environmental indicators of sustainability
factors that help us determine the health of the environment and guide us toward sustainable use of the earth’s resources
biodiversity
genetic, species, and ecosystem
higher biodiversity = healthier ecosystems
declining biodiversity can indicate pollution, habitat destruction, or climate change
global extinction rate is a strong environmental indicator since species extinction decreases global species richness
food production
indicates ability of earth’s soil, water, and climate to support agriculture
major threats to food production:
climate change
soil degradation
groundwater depletion
increasing meat consumption = further strain on food production
global grain production per capita has leveled off and shown signs of decline as of recent
atmospheric temperature and carbon dioxide
life on earth depends on a very narrow temperature range
carbon dioxide is a greenhouse gas, increasing temperature
deforestation and combustion of fossil fuels increases atmospheric carbon dioxide
increasing carbon dioxide is unsustainable
human population and resource depletion
as human population grows, resource depletion grows
resources are harvested unsustainably from natural ecosystems and degrade ecosystem health
more paper leads to deforestation
more food leads to soil erosion, deforestation, groundwater depletion
more travel leads to fossil fuel mining leads to air/water/soil pollution and habitat destruction
environmental consequences of urban runoff
decreased infiltration (groundwater recharge
rain washes pollutants into storm drains and into local surface waters
pollutants and effects:
salt:
plant and insect death
sediment:
turbidity
fertilizer:
eutrophication
pesticides:
kill non-target species
oil and gasoline:
suffocate fish/kill aquatic insects
solution:
rain gardens:
permeable pavement
public transit
building up, not out
permeable pavement
specially designed to allow stormwater to infiltrate and recharge ground water
decreases runoff, decreasing pollutants carried into storm drains and local surface water
decreases likelihood of flooding during heavy rainfall
more costly than traditional pavement
rain gardens
gardens planted in urban areas, especially surrounding a storm drain
decreases runoff by allowing it to soak into garden soil surrounding storm drain
decreases likelihood of flooding during heavy rainfall
creates habitat for pollinators, sense of place, and stores carbon dioxide
public transit
more cars on road leads to more pollutants on streets to runoff into storm drains and local waters
motor oil
gasoline
tire pieces
antifreeze
more cars = more lanes and parking lots (impervious surfaces) and more stormwater runoff
public transit decreases urban runoff, pollutants on road, carbon dioxide emissions, and traffic
building up, not out
building vertically decreases impervious surfaces and urban runoff
can be combined with a green roof or rooftop gardens to further decrease runoff
green roof also sequesters carbon dioxide and filters air pollutants out
plants absorb NO2, PM, and other pollutants into stomata and store them in tissue or soil
Integrated Pest Management
also known as IPM
reduces the risk that pesticides pose to wildlife, water supplies, and human health
minimizes disruptions to the environment and threats to human health
can be complex and expensive
pest control methods are:
biocontrol
crop rotation
intercropping
Biocontrol
introducing a natural predator, parasite, or a competitor to control the pest population
can include actually purchasing and spreading the control organisms or building homes for them / planting a habitat they need to attract them naturally
ladybugs for aphids
spiders for many pest insects
parasitic wasps for caterpillars
crop rotation
many pests prefer one specific crop or crop family. they lay eggs in the soil, so when larvae hatch, they have preferred food sources
rotating crops can prevent pests from becoming established since it disrupts their preferred food choice
also disrupts weed growth since different crops can be planted at different times, preventing bare soil from being taken over by weeds.
intercropping
“push-pull” system can be used
push plants emit volatile chemicals that naturally repel pests
pull plants emit chemicals that attract pests to them instead of the crop
can provide habitat or pull plants that emit chemicals that attract the pests predators.
soil conservation
prevents loss of:
nutrients in topsoil
soil moisture
decomposers in soil
organic matter that traps soil moisture
contour plowing
plowing parallel to natural slopes of the land instead of down slopes. prevents water runoff and soil erosion.
forms mini terraces that catch water running off, conserving soil and water
terracing
cutting flat platforms of soil into a steep slope
flatness of terraces catches water and prevents it from becoming runoff and eroding soil
perennial crops
crops that live year-round and are harvested numerous times
longer, more established roots and prevention of bare soil between harvest
windbreaks
using trees or other plants to block the force of the wind from eroding topsoil
can be used as a source of firewood or fruit
can provide habitat for pollinators or other species
no till
leaving leftover crop remains in soil instead of tilling under
adds organic matter to soil
prevents erosion from loosened soil
strip cropping
another name for intercropping
alternating rows of dense crops with rows of less dense crops to prevent runoff from eroding soil from less dense rows of crops.
crop rotation
replanting the same crops continuously depletes soil of the same nutrients
crop rotation can allow soil to recover from nitrogen-demanding crops like corn
peas/beans have nitrogen fixing bacteria in their root nodules that can return nitrogen to the soil
green manure
leftover plant matter from a cover crop, a crop planted in the offseason, between harvest and replanting of main crop
cover crop roots stabilize soil, limiting erosion
remains of cover crops left on field breakdown to release nutrients in the soil
limestone
limestone releases calcium carbonate (base) which neutralizes acidic soil
acidic soil has high H+ ion concentration which displaces + charge nutrients from soil
acidic soil also makes toxic metals more soluble in soil
calcium is a needed plant nutrient as well
rotational grazing
regular rotation of livestock to different pastures to prevent overgrazing
aquaculture
raising fish or other aquatic species in underwater enclosures. some benefits are:
it’s expanded because of its efficiency
requires only small amounts of water, space, and fuel
reduces risk of fishery collapse (90% population decline)
doesn’t take up any land space
drawbacks:
high density aquatic life produce a high waste concentration
increased risk of e. coli contamination, eutrophication, etc.
high density increases disease risk which can be spread to wildlife too
may introduce non-native species or GMOs to a local ecosystem if fish escape
fish are fed antibiotics which contaminates water via their waste
parasites are common due to density
forestry
using trees for lumber
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Flashcard (21)