SOMETHING

Tragedy of the Commons

individuals will use shared/public resources in their own self interest, degrading them

Key concepts that make up TOC

•must be a public resource (not privately owned)
•must be degraded, overused, depleted, used-up in some way

Example of TOC

•overgrazing
•overfishing
•water and air pollution
•overuse of groundwater

Why does TOC occur?

•when no one owns the resource (land, water, air) no one 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

What's the problem with TOC?

•overfishing can lead to fishery collapse (population crash) loss of income and starvation
•air pollution from coal power plants can lead to bronchitis, asthma, increased health care costs
•pesticide runoff from farms contaminates drinking water

Externalities

negative costs associated with human actions, that aren't accounted for in the price (unintended side-effects) *unintended consequence*

How to solve the TOC

•private land ownership (individual or government)
•fees or taxes for use
•taxes, fines, criminal charges for pollution of shared air, soil, water resources

Example of solutions for TOC

•clean air act
•clean water act
•safe drinking water act
•BLM (bureau of land management): manage rangelands in western US by collecting grazing fees from ranchers, evaluating land, and repairing effects of overgrazing

Direct effects of clearcutting (soil erosion)

•caused by loss of stabilizing root structure
•removes soil organic matter & nutrients form forest
•deposits sediments in local streams (warms water & makes it more turbid *cloudy*)

Direct effects of clearcutting (increased soil & stream temperature)

•loss of tree shade increases soil temperature (soil has lower albedo than leaves of trees)
•loss of tree shade along rivers & streams also warms them (erosion of sediments into rivers also warms them)

Direct effects of clearcutting (flooding & landslides)

•logging machinery compacts soil
•increased sunlight dries out soil
•loss of root structure = erosion of topsoil & O horizon

Tree plantations

areas where the same tree species are repeatedly planted, grown, and harvested

Tree plantations (lowers biodiversity)

•biodiverse, mature forests are replaced with single species forests
•less species diversity = lower resilience
•less habitat diversity for other organisms

Tree plantations (all the same age)

•all trees planted at the same time = all the same age
•lowers biodiversity further (no dead trees for woodpeckers, insects, decomposers)

Forest Benefits

•filtering of air pollutants
•removal & storage of CO2 from atmosphere
•habitat for organisms

Deforestation consequences

•reduces air filtering and carbon storing services
•cutting trees down releases CO2 from decomposition of leftover organic material
•slash & burn method of clearing land for agriculture by cutting trees & burning them releases CO2, N2O and water vapor into the atmosphere (all GHGs)

The Green Revolution

•shift in agriculture away from small, family operated farms to large, industrial-scale agribusiness
•increased use of mechanization, GMOs, irrigation, fertilizers, and pesticides

The Green Revolution PROS

•greatly increases efficiency of lands, short-term profitability, and food supply
•decreased world hunger and increased earth's carrying capacity for humans

The Green Revolution CONS

•soil erosion
•biodiversity loss
•ground surface water contamination

Mechanization PROS

•increased use of tractors for plowing and tilling fields, and combines for harvesting = increased yield + profits

Mechanization CONS

•increases reliance on fossil fuels (gasoline/diesel fuel) *emits GHGs to atmosphere → climate change*
•heavy machinery also compacts soil, decreasing H2O holding capacity *makes topsoil more prone to erosion*

High Yield Variety (HYV) Crops

•hybrid, or genetically modified crops that produce a higher yield (amount of crop produced per unit of area)
•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
•Example = Bt corn

Synthetic fertilizer

•shifts from organic fertilizer (like manure and compost) to synthetic fertilizers (man made from ammonium, nitrate, phosphate)
•PRO = increases yield and profits with more key nutrients needed for plant growth (N, P, K) added to the soil
•CONS = excess nitrate, phosphate are washed off fields and into nearby waters where they cause eutrophication; requires FFs for productions, releasing CO2

Irrigation

-drawing water from the ground or nearby surface waters and distributing it on fields to increase plant growth

Pesticides

-increase in use of synthetic pesticides-chemicals sprayed on crops that kill weds, insects, rodents, and other pests that at or damage crops

Pesticide PRO

-increases yield and profits with fewer plants lost to pests

Pesticide CONS

can wash off crops in runoff and kill or harm non-target species in local soil or waters

Pesticides examples

-DDT thinned shells of bird eggs, especially eagles
-atrazine turns amphibians and fish intersex

High Yield Crop Variety (HYV) PRO

-increased yield and food stability in regions previously prone to famine (India, Pakistan, Mexico)

GMOs PRO

-increases profitability with fewer plants lost to drought, disease, or pests + larger plant size + yield/acre

GMOs CONS

-GMO crops are genetically identical so genetic diversity is decreased and susceptibility to diseases or pest is increased

Synthetic Fertilizer PRO

-increases yield and profits with more key nutrients needed for plant growth (N, P, K) added to the soil

Synthetic Fertilizer CONS

-excess nitrate, phosphate are washed off fields and into nearby waters where they cause eutrophication
-requires FFs for production, releasing CO2
-don't return organic matter to soil, no increased H2O capacity and no soil decomposers

Irrigation PRO

-make agriculture possible in many parts of the world that are naturally too dry

Irrigation CONS

-can deplete groundwater sources, especially aquifers
-over watering can drown roots (no O2 access) and cause soil salinization (increase salt level in soil)

Monocropping

-growing on single species (corn, wheat, soy) of crop

Monocropping PRO

highly efficient for harvest, pesticide and fertilizer application

Monocropping CONS

-greatly decreases biodiversity (more prone to pests, fewer natural predators)
-increases soil erosion (crops harvested all at once & soil left bare)
-decreases habitat diversity for species living in the area

Tilling

mixing and breaking up soil to make planting easier-also loosens soil for roots

Tilling CONS

-increases erosion by loosening topsoil, breaking up leftover root structure from harvest
-loss of organic matter and topsoil nutrients over time
-increased PM in air (rerp. irr) and sediments in nearby water (turbidity

Slash and burn

cutting down vegetation and burning it to clear land for agriculture and return nutrients in plants to soil

Slash and burn CONS

-deforestation (loss of habitat biodiversity, CO2 sequestration (storage), loss of air pollution filtration
-releases CO2, CO, N2O-all GHGs that lead to global warming
-increases PM in air (asthma)
-lowers albedo, making area warmer

Leaching

-water carries excess nutrients (nitrates and phosphates) into groundwater or into surface waters runoff
-contaminates groundwater for drinking
-causes eutrophication of surface waters

Furrow irrigation

-trench dug along crops & filled with water
-easy and inexpensive; water seeps into soil slowly
-66% efficient, 33% lost to runoff and evaporation

Drip irrigation

-most efficient, but also most costly
-over 95% efficient
-holes in hose allow water to slowly drip out
-avoids waterlogging & conserves waters

Flood irrigation

-flood entire field; easier but more disruptive to plants
-can waterlog the soil & drown plants
-80% efficient, 20% runoff/evaporation

Spray irrigation

-ground or surface water pumped into spray nozzles
-more efficient (less water loss to runoff or evaporation)
-more expensive (equipment)

Waterlogging

-overwatering can saturate the soil, filling all soil pore space with water

Waterlogging problems

-doesn't allow air into pores, so roots can't take in O2 they need
-can stunt growth or kill crops

Waterlogging solution

drip irrigation, or soil aeration-poking holes or cores in soil to allow air in & water to drain through soil

Soil salinization

-salinization is the process of salt building up in soil over time
-groundwater used for irrigation naturally has small amounts of salt

Soil salinization problems

-water evaporates, and salt is left behind in soil. Over time, it can reach toxic levels, dehydrating plant roots & preventing growth

Soil salinization solution

drip irrigation, soil aeration, flushing with fresh water, switch to freshwater source

Global Human Water Use-industrial

power plants, metal/plastic manufacturing

Global Human Water Use - municipal

household (toilet, shower, drinking water)

Global Human Water Use- agriculture

water for livestock, irrigation water for crops

Groundwater

H2) stores in pore space of permeable rock and sediment layers

Aquifers

-useable groundwater deposits for humans
-refill at recharge areas
-unconfined aquifers recharge quickly
-confined aquifers recharge are longer-term water deposits that recharge more slowly

CAFOs

also called feedlots-densely crowded method where animals are fed grain (corn) to raise them to as quickly as possible

CAFOs PROS

-maximizes land use and profit (most meat production per/unit of area)
-minimizes cost of meat for consumers

CAFOs CONS

-given antibiotics & growth hormones to prevent disease outbreak & speed meat production
-animals produce large volume of waste which can contaminate nearby surface or groundwater
-produces large amount of CO2, CH4 (methane), and N2O (greenhouse gases -> climate change)

Manure lagoons

-large, open storage pits for animal waste
-waste contains: ammonia, hormone, antibiotics, e. coli
-heavy rain can flood lagoons & contaminate nearby surface and groundwater with runoff
-denitrification of ammonia in manure produces N2O
-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

Free-range grazing PROS

-no need for antibiotics with dispersed pop.
-doesn't require production of corn to feed animals
-waste is dispersed over land naturally, acting as fertilizer instead of building up in lagoons
-animals can graze on land too dry for most crop growth

Free-range grazing CONS

-requires more total land use/pound of meat produced
-more expensive to consume

Overgrazing problems

-too many animals grazing an area of land can remove all the vegetation (grass) which leads to topsoil erosion
-animals also compact soil, decreasing H2O; holding capacity -> more erosion

Overgrazing solutions

-rotational grazing (moving animals periodically) can prevent overgrazing
-can even increase growth of grass by distributing manure (natural fertilizer) & clipping grass back to size where growth is most rapid

Desertification

can occur if plants are killed by overgrazing & soil compacted so much that it can't hold enough water anymore

Inefficiency of Meat

producing meat for human to eat is far less efficient than producing plants in terms of energy, land and water use

Inefficiency of Meat (Energy)

all of the energy needed to plant, grow, harvest plants to feed to animals PLUS:
•energy needed to bring water to animals
•energy needed to house animals
•energy needed to slaughter & package

Inefficiency of Meat (Land)

all of the energy needed to grow plants to feed animals PLUS room the animals take up

Inefficiency of Meat (Water)

all of the water for corps that animals eat PLUS the water the animals drink

Fisheries

populations of fish used for commercial fishing

Fishery collapse

when overfishing causes 90% population decline in a fishery

Fishery collapse problems

•decreases genetic biodiversity of fish populations and species biodiversity of ocean ecosystems if species are lost from ecosystem
•economic consequences: lost income for fishermen, lost tourism, dollars for communities

Bottom trawling

especially harmful fishing technique that involves dragging a large net along the ocean floor

Bottom trawling problems

•bycatch: unintended species like dolphins, whales, turtles caught in nets
•stir up ocean sediment (turbidity) and destroys coral reef structure

Urbanization

•removing of vegetation to convert natural landscape to city
•replaces soil, vegetation, wetlands, with impervious surfaces (concrete, asphalt, cement) which don't allow water to infiltrate into the ground

What does urbanization prevent?

it prevents groundwater recharge, causing precipitation to runoff into local bodies of water

population growth in coastal cities can lead to saltwater intrusion due to. . .

•sea level rise
•excessive groundwater withdrawal

Sea level rise

due to warming of ocean (thermal expansion) and melting of ice caps (increasing ocean volume) can contaminate fresh groundwater with salt

Excessive groundwater withdrawal

near coast lowering water table pressure, allowing saltwater to seep into groundwater

Trend in Pop.

•people move from rural to urban areas for jobs, entertainment, cultural attractions
•urban areas are more densely populated, minimizing driving & land use per person (decreases env. impact per person)
•highest growth currently it suburban population

Urban sprawl

population movement out of dense, urban centers to less dense suburban areas surrounding the city

Urban sprawl causes

•cheaper property in suburbs than in cities
•domino effect
•cars make it easy to still get from the suburbs into the city for work, entertainment, cultural attractions
•highway expansion

Urban sprawl solutions

• urban growth boundaries: zoning laws set by cities preventing development beyond a certain boundary

• public transport and walkable city design that attract residents to stay

• mixed land use: residential, business, and entertainment buildings all located in the same area of a city (enables walkability and a sense of place)

Ecological footprint

measures of how much a person/group consumes, expressed in area of land

IPM (Integrated Pest Management)

•using a variety of pest control methods that minimize env. disruption and pesticide use
•researching and monitoring pests and targeting methods to specific pest life cycles

Biocontrol

•introducing a natural predator, parasite, or competitor to control the pest population
•can include actually purchasing and spreading the control organisms in fields, or building homes for them/planting habitat they need to attract them naturally

Biocontrol examples

•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 source

Crop rotation benefits

•rotating crops can prevent pests from becoming established since it disrupts their preferred food choice
•disrupts weed growth since diff. crops can be planted at different times, preventing bare soil from being taken over by weeds

Intercropping

planting different types of crops in alternating bands or other spatially mixed arrangements

"Push" plants

emit volatile chemicals that naturally repel pests away from crop

"Pull" plants

emit chemicals that attract moths to lay eggs in them, instead of crop

IPM PROS

•reduces death and mutation of non-target species
•reduces effect on human consumers of produce
•reduces contamination of surface and ground water by agricultural runoff with pesticides

IPM CONS

•can be more time consuming & costly than just crop dusting pesticides

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