APES Unit 5: Land And Water Use

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