5.1 - Tragedy of the Commons (TOC)

Tragedy of the Commons:

• Individuals will use shared/public resources* in their own self-interest, degrading** them

  • *Must be a public resource (not privately owned)

  • **Must be degraded, overused, depleted, used up in some way\

• Examples:

  • Overgrazing, overfishing, water and air pollution, overuse of groundwater

Why Does it Happen:

• 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, or polluting many public resources

What’s the Problem:

• 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

• Air pollution from coal power plants can lead to bronchitis, asthma, increased healthcare costs

• Pesticide runoff from farms contaminates drinking water

How to Solve the TOC:

• Private land ownership (individual or government)

• Fees or taxes for use

  • Ex. permit system for grazing, logging

• Taxes, fines, criminal charges for pollution, or shared air/soil/water resources

  • Examples:

    • Clean Air Act

    • Clean Water Act

    • Safe Drinking Water Act

• BLM (Bureau of Land Management)

  • Manages rangelands in the western US by collecting grazing fees from ranchers, evaluating land, and repairing effects of overgrazing

5.11 - Ecological Footprint

Ecological Footprint

• The measure of how much land a person/group consumes, expressed in area of land

• Factors (Land required for):

  • Food production

  • Raw materials (wood, metal, plastic)

  • Housing

  • Electricity production

    • Coal, natural gas, solar, wind, etc.

  • Disposing waste produced (landfill space)

Ecological Footprint vs. Carbon Footprint

• Ecological Footprint: measured in land (gha - global hectare) which is a biologically productive hectare (2.47 acres)

• Carbon Footprint: measured in tonnes of CO2 produced per year

  • All CO2 released from an individual or group consumption and activities

    • Material goods

    • Food production

    • Energy use (gasoline, heat, electricity)

Factors That Affect Footprint

• Increase Footprint

  • Affluence (wealth) increases carbon and ecological footprint

    • Larger houses

    • More travel (gas)

    • More resources are needed for material goods (cars, etc.)

  • Meat Consumption - more land, more water, more energy

  • Fossil fuel usage (heating, electricity, travel, plastic)

• Decrease Footprint

  • Renewable energy use (wind, solar, hydroelectric)

  • Public transportation (less gas)

  • Plant-based diet

  • Less consumption, less travel, less energy use

If The Whole World Lived Like Us

• Ecological footprint can also be expressed in the “number of earths” required if the entire world consumed the same level of resources as a given individual or group

  • The current average US footprint is 5.1 Earths

    • 5.1 earth’s worth of resources needed if the entire world consumed resources of leverage American

  • The current global footprint is 1.85 earths

    • This means that each year, humanity consumes 1.85 times what the Earth can produce in a year

5.3 - The Green Revolution

The Green Revolution

• A shift in agriculture away from small, family-operated farms to large, industrial-scale agribusiness

  • Increased use of mechanization, GMOs, irrigation, fertilizers, and pesticides

• Positive:

  • Greatly increases the efficiency of lands, short-term profitability, and food supply

    • Decreased world hunger and increased earth’s carrying capacity for humans

• Negative:

  • Bring neg. Consequences (soil erosion, biodiversity loss, ground & surface water contamination)

Mechanization

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

• Negative

  • 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

GMOs

• Genetically modified crops have genes for drought tolerance, pest resistance, faster growth, and larger fruit/grain

  • Positive:

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

  • Negative:

    • GMO crops are all genetically identical so gen. diversity is decreased and susceptibility to diseases or pest is increased

  • Ex:

    • Bt corn has been modified with a gene from soil bacteria (Bacillus thuringiensis) to produce a protein that kills many different corn pests

      • 

Synthetic Fertilizer

• Shift from organic fertilizers (like manure and compost) to synthetic fertilizers (man-made ammonium, nitrate, phosphate)

  • Positive:

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

  • Negative:

    • Excess nitrate, phosphate are washed off fields and into nearby waters where they cause eutrophication (algae blooms)

    • Require FFs for production, releasing CO2 (climate change)

Irrigation

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

  • Positive:

    • Make agriculture possible in many parts of the world that are naturally too dry (don’t receive enough rain)

  • Negative:

    • Can deplete groundwater sources, especially aquifers

    • Overwatering can drown roots (no O2 access) and cause soil salinization (increase salt level in soil)

Pesticides

• Increase in use of synthetic pesticides - chemicals sprayed on crops that kill weeds, insects, rodents and other pests that eat or damage crops

  • Positive:

    • Increases yield and profits with fewer plants lost to pests

  • Negative:

    • Can wash off crops in runoff and kill or harm non-target species in local soil or waters (bees especially)

      • Ex:

        • DDT thinned shells of bird eggs, especially eagles

          Atrazine turns amphibians and fish intersex

5.4 - Impact of Agricultural Practices

Monocropping

• Growing one single species (corn, wheat, soy) of crop

  • Positive:

    • Highly efficient for harvest, pesticide and fertilizer application

  • Negative:

    • Greatly decreases biodiversity (more prone to pests, fewer nat. 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

  • Positive:

    • Also loosens soil for roots

  • Negative:

    • Increases erosion by loosening topsoil, breaking up leftover root structure from harvest

    • Loss of organic matter & topsoil nutrients over time

    • Increased PM in air (rerp. irr) and sediments in nearby water (turbidity)

Slash & Burn

• Cutting down vegetation and burning it to clear land for ag. & return nutrients in plants to soil

  • Negative:

    • Deforestation

      • Loss of: habitat, biodiv, 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

Synthetic (inorganic fertilizers)

• Don’t return organic matter to soil; no increased H2O holding cap. & no soil decomposers

• Leaching: water carries excess nutrients (nitrates and phosphates) into groundwater or into surface waters (as runoff)

  • Contaminates groundwater for drinking

  • Causes eutrophication of surface waters

5.5 - Irrigation

• Furrow Irrigation:

  • Trench dug along crops & filled with water

  • Easy & inexpensive; water seeps into soil slowly

  • ~66% efficient, 33% lost to runoff & evap.

• 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/evap.

• Spray Irrigation:

  • Ground or surface water pumped into spray nozzles

  • More efficient (less water loss) than flood or furrow

  • More expensive (requires energy for pumps & movement of sprinklers

Waterlogging

• Overwatering can saturate the soil, filling all soil pore space with water

  • Doesn’t allow air into pores, so roots can’t take in 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 & water to drain through soil

Soil Salinization

• Salinization is the process of salt building up in a soil over time

• Groundwater used for irrigation naturally has small amounts of salt

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

• Solution:

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

Global Human Power Use

• Industrial: power plants, metal/plastic manufacturing

• Municipal: households (toilet, shower, drinking water)

• Agriculture: water for livestock, irrigation water for crops

Aquifers and Groundwater

• Groundwater: H2O stored in pore space of permeable rock & sediment layers

• Aquifers: useable groundwater deposits for humans

• Replenished by groundwater recharge (rain water percolating down through soil into aquifer)

• Unconfined aquifers recharge quickly

• Confined aquifers recharge are longer-term water deposits that recharge more slowly

Depletion of Aquifers

• Saltwater Intrusion: excessive pumping near coast lowers water table pressure, allowing saltwater to seep into groundwater

• Cone of depression: forms when water table is lowered by excessive pumping, depleting water & drying nearby wells

5.6 - Pest Control Methods

Pesticides

• Chemicals that are toxic to pests

  • Rodenticides kill rodents

  • Fungicides kill fungi

  • Insecticides kill insects

  • Herbicides kill plants

• Can cause pests to become resistant to pesticides with overuse

  • Genetic biodiversity gives some pests resistant traits to pesticide

  • Pesticide artificially selects for pests with resistance by killing all the non-resistant individuals, leaving only resistant ones

GMOs (Genetic Modification)

• Gene for pest resistant trait is added to the plant through genetic modification

  • Bt corn with bacteria gene that produces Bt crystals toxic to pests

  • Roundup Ready crops are GM to be resistant to broad herbicide (Roundup) meaning roundup will kill weeds, but not crops

GMOs and Pesticide Use

• Roundup Ready crops have increased herbicide (glyphosate) use since crops can’t be harmed by it

• Bt corn has decreased insecticide use since corn makes its own insecticide (Bt crystals)

GMOs and Genetic Diversity

• GM crops are all genetically identical (clones) so there is no genetic diversity in the pop.

• If there is a disease or pest that does affect the GM crops, they’re all vulnerable and there’s no chance of a genetic mutation providing an adaptive trait

5.14 - Integrated Pest Management (IPM)

IPM Basics

• Using a variety of pest control methods that minimize env. disruption and pesticide use

  • Researching & monitoring pests and targeting methods to specific pest life cycles

  • Biocontrol (Bringing in a natural predator or parasite to control the pest)

  • Crop rotation

  • Intercropping

Biocontrol

• Introducing a natural predator, parasite, or competitor to control the pest population

• Can include actually purchasing & spreading the control organisms in fields, or building homes for them/planting habitat they need to attract them naturally

  • Ladybugs for aphids

  • Spiders for many pest insects

  • Parasite 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.

  • Rotating crops (planting a different crop each season) can prevent pests from becoming established since it disrupts their preferred food choice

  • Also disrupts weed growth since diff. 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 away from crop

  • “Pull” plants emit chemicals that attract moths to lay eggs in them, instead of crop

  • Can provide habitat, or “pull” plants that emit chemicals that attract natural pest predators

Benefits and Drawbacks of IPM

• Benefits:

  • Reduces death & mutation of non-target species from

    • Ex:

      • intersex frogs (atrazine)

      • Eagle death (DDT)

      • Bee die offs (glyphosate)

  • Reduces effects on human consumers of produce

    • Ex:

      • many pesticides are carcinogens (cause cancer)

  • Reduces contamination of surface & ground water by agricultural runoff with pesticides

• Drawbacks:

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

    • Ex:

      • researching specific pests & planting numerous species of crops

5.7 - Meat Production Methods

CAFOs

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

  • Positive:

    • Maximizes land use and profit (most meat production per/unit of area)

      • Minimizes cost of meat for consumers

  • Negative:

    • 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 amounts of CO2, CH4 (methane), and N2O (greenhouse gasses → climate change)

Manure Lagoons

• Large, open storage pits for animal waste (manure)

• Waste contains: ammonia (N), hormones, antibiotics, fecal coliform bacteria (e. coli)

  • e. Coli → toxic to humans

  • Ammonia (N) → eutrophication

  • Antibiotics & growth hormones → alter endocrine (hormonal system) of humans

• Heavy rain can flood lagoons & 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 & grow at a natural rate without growth hormones

  • Positive:

    • 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

  • Negative:

    • Requires more total land use/pound of meat produced

      • More expensive to consumer

Overgrazing

• 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

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

• Solution:

  • 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

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: 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 and package

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

• Water: all of the water for crops that animals eat PLUS the water the animals drink

Impacts of Overfishing

• Fisheries: populations of fish used for commercial fishing

• Fishery collapse: when overfishing causes 90% population decline in a fishery

  • Pop. may never recover from fishery collapse due to: decreased biodiversity, inability to find mates, inbreeding depression

• Negative:

  • Pop. may never recover from fishery collapse due to: decreased biodiversity, inability to find mates, inbreeding depression

  • Economic consequences: lost income for fishermen, lost tourism dollars for communities

Economic Impact

• Overfishing in period of 1975 - 1985 led to sharp loss of profits from 1985 - 2018

• Tragedy of the Commons: no incentive or penalty to prevent overfishing from 75’ - 85’

Bottom Trawling

• Especially harmful fishing method that involves dragging a large net along the ocean floor

  • Negative:

    • Bycatch: unintended species like dolphins, whales, turtles caught in nets

    • Stirs up ocean sediment (turbidity) & destroys coral reef structure

    • Decreases biodiv. by killing non-target species & 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 pop. limits fishery recovery and decreases food supply of marine mammals & seabirds

5.9 - Mining

Mining Basics

• 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, & rocks that are removed to get to an ore deposit below

• Tailings & slag: leftover waste material separated from the valuable metal or mineral within ore (often stored in ponds at mine site)

Surface Mining

• Removal of overburden to access ore near surface

• Different types: open pit, strip, mountaintop removal, placer

  • Mnt. top removal = esp. damaging to landscape & habitats, streams nearby

• Negative:

  • Mnt. top removal = esp. damaging to landscape & habitats, streams nearby

    • Topsoil erosion

    • Habitat loss

    • Increased stream turb.

    • Increase PM in air

• As ore near surface becomes more scarce, mining moves deeper underground to subsurface mining (more dangerous & expensive)

Subsurface Mining

• More expensive due to higher insurance & health care costs for workers

• Risks: poor ventilation leading to toxic gas exposure, mine shaft collapse, injury from falling rock, lung cancer, asbestos, fires, explosions

• Vertical “shaft” drilled down into ground

  • Elevator to carry down workers & transport out resource

  • Often used for coal

• Increasingly used as surface coal deposits are depleted

Environmental Impacts of Mining

• Rainwater carrier sulfuric acid into nearby streams, or infiltrates ground water

• Lowers pH of water, making toxic metals like mercury & aluminum more soluble in water sources (killing aquatic org.)

• Methane Release: coal mining releases methane gas (CH4) from rock around coal

  • Vented out of mine to prevent explosion & continues seeping out after mine closes

  • GHG → climate change

• PM Release: coal mining especially, releases lots of soot and other particulates that can irritate human & animal lung

• Acid mine drainage: rainwater leaks into abandoned mine tunnels & mixes with pyrite, forming sulfuric acid

• Negative:

  • Topsoil erosion

  • Habitat loss

  • Increased stream turb.

Mine Reclamation

• Process of restoring land to original state after mining has finished

• Includes:

  • Filling of empty mine shafts/hole

  • Restoring original contours of land

  • Returning topsoil, with acids, metals, and tailings removed

  • Replanting of native plants to restore community to as close to original state as possible

5.10 - Urbanization

Urbanization

• Removing of vegetation to convert natural landscape to city (urban)

• Replaces soil, vegetation, wetlands , with impervious surfaces (concrete, asphalt, cement) which don’t allow water to infiltrate into the ground

• CO2 emissions:

  • Cement production

  • Construction machinery

  • Deforestation (loss of future carbon sequestration + decomposition of cut trees)

  • Landfills needed for disposing trash from large pop.

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

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 → 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 is suburban population

• Overall trend in US & many other nations is away from less dense rural (country) areas and toward more urban (city) areas

  • Suburbs: less dense areas surrounding urban areas

Urban Sprawl

• Pop. movement out of dense, urban centers to less dense suburban areas surrounding the city (GR → Kentwood, Wyoming, F. Hills, etc.)

• 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, 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 + businesses create blight (unsightly, rundown infrastructure) so more people leave

Urban Sprawl Consequences

• 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 and easier to commute from suburbs into urban areas

• Solutions:

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

  • Public transport & 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 & sense of place

5.2 - Clearcutting

Direct Effects of Clearcutting

• Soil Erosion

  • Caused by loss of stabilizing root structure

  • Removes soil organic matter & nutrients from forest

  • Deposits sediments in local streams

    • Warms water & makes it more turbid (cloudy)

• Increased Soil and stream temp.

  • Loss of tree shade increases soil temperature

    • Soil has lower albedo than leaves of trees

  • Loss of tree shade along rivers & streams warms them

    • Erosion of sediments into rivers also warms them

• Flooding and Landslides

  • Logging machinery compacts soil

  • Increased sunlight dries out soil

  • Loss of root structure = erosion of topsoil & O horizon

    • All of these factors decrease H2O holding capacity of soil causing flooding & landslides

Tree Plantations

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

  • Lowers Biodiversity

    • Biodiverse, mature forests are replaced with single species forests

    • Less species diversity = lower resilience

    • Less habitat diversity for other org.

  • 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

  • Stomata (leaf pores) remove VOCs, NO2, PM from air & store in tree

• Removal and storage of CO2 from atmosphere

  • Trees take in CO2, store carbon as sugar, wood, other tissue & release O2

• Habitat for organisms

  • Many organisms live in forests (biodiv, ecotourism)

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)

5.12 - Sustainability

Sustainability

• Consuming a resource or using a space in a way that does not deplete or degrade it for future generations

  • using compost (renewable) over synthetic fertilizer (fossil fuel dependent)

Maximum Sustainable Yield

• The maximum amount of a renewable resource that can be harvested without reducing or depleting the resource for future use

  • Roughly ½ carrying capacity. Maximizes yield (resource harvest) and regeneration rate of the population

Environment Indicators of Sustainability

• Factors that help us determine the health of the environment and guide us towards sustainable use of earth’s resources

  • Biodiversity

    • Genetic, species, and ecosystem

    • Higher biodiv. = healthier ecosystems

    • Declining biodiversity can indicate pollution, habitat destruction, and climate change

    • Global extinction rate = strong environment indicator since species extinction

Food Production

• Indicates ability of earth’s soil, water, and climate to support ag.

• Major threats to food prod. = Climate change, soil degradation (desertification, topsoil erosion), groundwater depletion

• Increasing meat consumption = further strain on food prod. (takes away water and land from grain production)

• Global grain production per capita has leveled off & sown signs of decline recently

Atmospheric Temp. and CO2

• Life on earth depends on very narrow temperature range

• CO2 is a GHG (traps infrared radiation & warms earth’s atm.)

  • Increased CO2 = increased temp.

• Deforestation (loss of CO2 sequestration) & combustion of FF (emission of CO2) increase atm. CO2

• Increasing CO2 = unsustainable (Dries out arable (farmable) land, destroys habitats, worsens storm intensity)

Human Population and Resource Depletion

• As human pop. grows, resource depletion grows

• Resources are harvested unsustainably from natural ecosystems & degrade ecosystem health

  • More paper (lumber) = deforestation

  • More food = soil erosion, deforestation, groundwater depletion

  • More travel = FF mining = air, water, soil pollution, habitat destruction

5.15 - Sustainable Agriculture

Soil Conservation

• Agricultural techniques that minimize erosion

  • (US is losing topsoil to erosion 10x faster than it forms)

• Prevents loss of:

  • Nutrients in topsoil

  • Soil moisture

  • Decomposers in topsoil

  • Organic matter that traps soil moisture

Contour Plowing

• Plowing parallel to natural slopes of the land instead of down slopes prevents water runoff & soil erosion

• Forms mini terraces that catch water running off, conserving soil & water

Terracing

• Cutting flat “platforms” of soil into a steep slope

• Flatness of terraces catches water & prevents it from becoming runoff and eroding soil

Perennial Crops

• Crops that live year round and are harvested numerous times

• Longer, more established roots & 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, fruit (income)

• Can provide habitat for pollinators & other species

No Till

• Leaving leftover crop remains in soil instead of tilling under

• Adds org. matter to soil (nutrients, soil cover, moisture)

• Prevents erosion from loosened soil

Strip Cropping

• Another name for intercropping

• Alternating rows of dense crops (hay, wheat) with rows of less dense crops (corn, soy, cotton) to prevent runoff from eroding soil from less dense rows of crops

Improving Soil Fertility

• Methods of restoring nutrient levels in the soil (N, P, Ca, Mg)

• Crop Rotation

  • Replanting same crops continuously depletes soil of the same nutrients

  • Crop rotation can allow soil to recover from nitrogen-demanding crops like corn

  • Peas/beans (legumes) have nitrogen fixing bacteria in their root nodules that can return nitrogen to the soil

• Green Manure

  

  • Green manure is leftover plant matter from a cover crop - a crop planted in the offseason, between harvest & replanting of main crop

    • Cover crop roots stabilize soil limiting topsoil erosion

    • Remains of cover crops (green manure) left on field breakdown to release nutrients into 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 (leeching them out)

    • Acidic soil also makes toxic metals (aluminum) more soluble in soil

    • Calcium is a needed plant nutrient as well

Rotational Grazing

• Regular rotation of livestock to different pastures to prevent overgrazing

  • Overgrazing can kill plants, compact soil, and lead to erosion of topsoil

  • Rotational grazing can actually promote pasture growth at faster than normal rate

  • Clips grass back to length where growth is fastest & encourages deeper root growth

5.16 - Aquaculture

Aquaculture Benefits

• Raising fish, or other aquatic species in cages/enclosures underwater

  • Requires only small amount of water, space, and fuel

  • Reduces risk of Fishery collapse (90% population decline in a fishery)

  • Doesn’t take up any land space (compared to beef, pork, chicken)

Aquaculture Drawbacks

• High density produces high concentration of waste (e. coli & eutrophication risks)

• High density increases disease risk, which can be transmitted to wild populations as well

• May introduce non-native species or GMOs to local ecosystem if captive fish escape

• Fish are fed antibiotics which can contaminate water via their waste

5.17 - Sustainable Forestry

Ecologically Sustainability Forestry

• Forestry (using trees for lumber) that minimizes damage to ecosystem (habitats destruction, soil erosion, etc.)

• Selective cutting or strip cutting

  • Only cutting some of the trees in an area (biggest & oldest) to preserve habitat (biodiv.) and topsoil

• Using human & pack animal labor to minimize soil compaction from machinery

• Replanting same species being logged

• Maximizes long-term productivity of land & preserves forest for future generations

Sustainable Forestry Practices

• Using recycled wood, or simply reusing without recycling (furniture, decoration)

• Wood can be chipped and used as mulch for gardens or agricultural fields

• Reforestation: replanting of trees in areas that have been deforested

• Selectively removing diseased trees to prevent spread of infection through entire forest

  • Removes host for disease

  • Decreases density, making spread less likely

Fire Suppression

• Stopping Natural Fires

  • Fire supressionsion is the practice of putting out all natural forest fires as soon as they start

• Leads to more biomass buildup

  • Putting out fires immediately leads to more dry biomass buildup

  • Makes future fires worse

• Monitoring Instead

  • Close monitoring can prevent fire damage & worse fires in the future

Prescribed Burns

• Dead biomass builds up

  • Fuel for large forest fires

  • Stored nutrients trapped in dead biomass

  • Dead trees = susceptible to disease & pest spread

• Small, controlled fires burn lots of dead biomass

  • Uses up dead biomass (fuel) preventing larger forest fires later

• Promotes nutrient recycling

  • Nutrients in dead biomass are recycled → new growth

4.6 - Watersheds

Watersheds

• All of the land that drains into a specific body of water (river, lake, bay, etc.)

  • Determined by slope; ridges of land divide watersheds (diff. runoff directions)

  • Vegetation, soil composition, slope play a large role in how watersheds drain

    • More vegetation: more infiltration and groundwater recharge

    • Greater slope: faster velocity of runoff and more soil erosion

    • Soil permeability: determines runoff versus infiltration rates

• Human activities of a watershed impact water quality

  • Ex.

    • agriculture, clearcutting, urbanization, dams, mining

Chesapeake Bay Watershed

• 6 state region that drains into a series of streams/rivers and eventually into Chesapeake Bay

  • Mix of fresh & salt water + nutrients in sediment make estuary habitats like the salt marshes in the bay highly productive

• Estuaries and wetlands provide ecosystem services:

  • Tourism revenue - hotels, restaurants, permits

  • Water filtration (grass roots trap pollutants)

  • Habitats for food sources (fish & crabs)

  • Storm protection (absorbing & buffering floods)

Human Impacts on the Chesapeake Bay

• Nutrient pollution (N and P) leads to eutrophication in the Bay

  • Algae bloom due to increase of N/P → decreased sunlight → plants below surface die → bacteria use up O2 for decomp. → hypoxia (low O2) & dead zones

• Major N/P sources:

  • Discharge from sewage treatment plants (N/P levels from human waste)

  • Animal waste from CAFOS

  • Synthetic fertilizer from ag. fields & lawns

• Other major pollutants:

  • Endocrine disruptors (from sewage treatment)

  • Sediment pollution (deforestation, urbanization, tilling ag. fields)

    • Increases turbidity (reduced photosynth) & covers over rocky streambed habitats

Solution to Watershed Pollutants:

5.13 Reducing Urban Runoff

Environmental Consequences of Urban Runoff

• Decreased infiltration (groundwater recharge)

• Rain washes pollutants into storm drains & 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: Permeable Pavement

• Specially designed to allow stormwater to infiltrate & recharge ground water

• Decreases runoff, decreasing pollutants carried into storm drains & into local surface water

• Decreases likelihood of flooding during heavy rainfall

• Negative:

  • More costly than traditional pavement

Solution: Rain garden

• 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

Solution: Public Transit

• More cars on the road = more pollutants on streets to runoff into storm drains & local waters

  • Motor oil

  • Tire pieces

  • Gasoline

  • Antifreeze

• More cars = more lanes & parking lots (impervious surfaces) & more stormwater runoff

• Public transit decreases urban runoff, pollutants on road, CO2 emissions & even traffic!

Solution: Building up, not out

• Building vertically decreases impervious surfaces (decreasing urban runoff)

• Can be combined with “green roof” or rooftop gardens to further decrease runoff

• Green roof also sequesters CO2 and filters air pollutants out

  • Plants absorb NO2, PM and other pollutants into stomata and store in tissue or soil