AP Environmental Science Course Review Part 2
AP Environmental Science Course Review Part 2
Evolution
Genetic changes in a population of species overtime
Adaptation: inherited traits that helps an organism better survive
Natural selection: some organisms are better able to survive and reproduce than others
Coevolution: 2 populations of species influence each others evolution over a long period of time
Poisonous newt + poison-resistant snake
Mutations: genetic changes in DNA that occur randomly and can encourage evolution
Types of Selection
Speciation
When a population ends up breaking into 2 populations in some way
Allopatric speciation: species are separated by a physical barrier and cannot cross-breed, leading to independent evolution and speciation
Sympatric: species are NOT separated but changes in behavior leads to lack of mating and eventual speciation
Types of Species
Indicator: alters us to changes in the environment earlier than either species due to their sensitivity to changes (ex. frogs)
Foundation: alters the environment in a way that influences other species (ex. Elephants that push trees, create paths in savanna)
Keystone: species that exert a large influence over an ecosystem and is dependent on by many other species (ex. otters)
Generalist species: occupy broad niches, eat a variety of food, can withstand varying conditions (ex. mice)
Specialist species: occupy specific narrow niches often with species food sources, sensitive to changes and more prone to extinction should conditions change (ex. koala)
Primary VS. Secondary Succession
Primary Succession | Secondary Succession |
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Intermediate disturbance hypothesis: Ecosystems can withstand a moderate amount of disturbance and it often increases biodiversity more than a low/high amount of disturbance
A high amount of disturbance>> extinctions
Biodiversity
Higher biodiversity = higher ecosystem/population resilience to disturbance
Species diversity: number and variety of species contained in a habitat
Species richness: number of species specifically
Species evenness: refers to whether or not species are in equal abundance
A rainforest would have high species evenness (lots of species + not one dominates)
Pine forest has low species evenness (pine trees are majority in ecosystem)
Island Biodiversity
Larger islands have greater biodiversity than smaller islands as do islands that are closer to the mainland
Larger islands have higher rates of migration of NEW species from the mainland as do closer islands than smaller islands and islands away
Range of Tolerance
Different types of changes in the ecosystems that an organism can withstand
Optimum range doesn't affect them
high/low= physiological stress or death (having to do w salinity, temp, DO, pH, etc)
Life Strategies
R-Selected | K-Selected |
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Growth Patterns
Population growth is limited by resource availability
Resources are always finite
When resources are abundant, population growth increase
When resources are scarce, unequal distribution may result in increased mortality + decreased fecundity (ability to produce new offspring)
Overshoot: refers to when a pop exceeds the carrying capacity of an ecosystem
Can result in environmental consequences such as resource degradation or dieback of population
Logistic Growth
As population approach limits on food/water/resources; carrying capacity (K) slows down pop growth
After approaching K, they'll be around stable
Exponential Growth
A lot of pop experiences early in their population
No limits on food/resources
Carrying Capacity: the maximum number of individuals the habitat can support based on food, water, and other resources (density-dependent factors)
Carrying capacity can change as available resources change
If populations overshoot carrying capacity, the lack of resources will result in a decline in pop #
Survivorship Curves
Type 1: longer lives, most make it to maturity, low infant deaths, less offspring produced, higher parental vcare
Ex. People, k-selected species
Increasing mortality with age
Type 2: equal chance of dying at any point in life
Ex. birds
Type 3: high infant deaths, those that do make it usually survive to adulthood, offspring often over-produced
R-selected species
Age Structures
Rapid growth:
wide pyramid with wide base (lots of younger individuals and likely lots of future growth)
Top is skinny: little access to medical care
Slow growth:
Lots of older individuals>loner life span and increased access to medical care
Zero growth:
Rectangular shaped; TFR is at replacement level (2.1)
Negative growth/decline
Total Fertility Rate
TFR: the numbers of babies on average that women in a country have (ages 15-45)
Replacement fertility: 2.1 (replaces mom and dad), leads to population stabilization
Higher TFR in less developed countries, lower TFR in more developed countries
Factors affecting TFR: medical care, jobs for women, death (infant), literacy in women, labor (needed for child labor), birth control access, government policies/laws
Population Math/Calculations
Population growth rate= (birth rate + immigration) - (death rate + emigration)/total pop) x 100
Doubling Time= 70/r; r=growth rate
Birth rate (as a %): (total births/total population) x 100
Crude birth rate (per 1,000)= (total births/total population) x 1000
Death Rate (as a %): (total deaths/total population) x 100
Crude Death rate (per 1,000)= (total deaths/total population) x 1000
Global population growth rate (r) = (CBR/1000-CDR/100) x 100
National population growth rate (r) - ((CBR+immigration)-(CDR+emigration))/10
Percent rate of change: (new-old)/(old) x 100
Demographic Transition Model
Characteristics of developing countries:
Higher infant mortality rates
More children in workforce
Lower life- expectancy
Lower rates of access to modern medicine, education, safe drinking water, and sanitation
Stage 1 Pre-industrial: high BR and DR
Ex. not good living condition, struggling economy, war-torn country
agrarian/agricultural (more children=financial benefit from farms)
Stage 2 Transitioning: dropping DR, still high BR
Life span begins to increase
Rapid pop growth
Stage 3 Industrial: low DR, declining BR
Pop growth begins to slow down
Increased education/opportunities increases age of first pregnancy decreasing # of children born per woman, more children=financial burden; increased average ay m marriage, increased access to contraception + family planning
Stage 4 Post-industrial: BR approaching DR
TFR may fall below RLF
Pop growth may be near 0, or negative
Human population growth (or decline) in a geographic area is influenced by:
Birth rates, infant mortality rates, death rates, access to family planning, access to education, age at marriage
Globally, human population growth is limited by:
Earth’s carrying capacity, food supply (population growth tends to grow exponentially but food supplies grow linearly- Malthusian’s theory)
Population growth can be affected by density-dependent or density-independent
Density dependent: factors affect a population more as the population size increases
Access to clean water, access to clean air, availability of food resoeces, disease transmission, territory size
Density-independent: factors that affect a population at the same rate, no matter what the population size
Major storms (hurricanes, tornadoes, tsunamis, etc); fires; prolonged heat waves; doughts
4.1 Plate Tectonics
Plate Tectonics: Theory explaining the movement of the Earth’s rigid lithospheric plates is the result of convection processes in the underlying partially molten mantle
Earth’s Structure
Core: Dense mass of solid nickel, iron, and radioactive elements that release heat
Mantle: liquid layer of magma surrounding the core, kept liquefied by intense heat from core
Asthenosphere: solid, flexible layer of mantle, beneath the lithosphere
Lithosphere: thin, brittle layer of rock floating on top of mantle ( broken up into tectonic plates
Crust: very outer layer of the lithosphere, Earth’s surface
Plate Boundaries
Divergent Plate Boundary: Plates move away from each other
Rising magma plume from mantle forces plates apart
Forms: mid-oceanic ridges, volcanoes, seafloor spreading, and rift valleys (on land)
Convergent Plate Boundary:Plates move towards each other
Leads to subduction (one plate being forced beneath another)
Forms: mountains, island arcs, earthquakes, and volcanoes
Transform fault Plate Boundary: plates slide past each other in opposite directions
Forms: earthquakes (occurs when the stress on lithospheric plates overcomes a locked fault, resulting in a release of energy)
Convection Cycles (Divergent): Magma heated by earth’s core rises towards lithosphere
Rising magma cools & expands, forcing oceanic plates apart
Creates, mid ocean ridges, volcanoes, spreading zones or “seafloor spreading”
Magma cools, and solidifies into new lithosphere
Magma heated by earth’s core rises towards lithosphere
Rising magma cools & expands, forcing oceanic plates apart
Creates, mid ocean ridges, volcanoes, spreading zones or “seafloor spreading”
Magma cools, and solidifies into new lithosphere
Convergent Boundary - Subduction Zone
Oceanic-Oceanic : one plate subducts underneath other
Forces magma up to lithosphere surface, forming mid ocean volcanoes
Island arcs
Off-shore trench
Oceanic-Continental : dense oceanic plate subducts beneath cont. Plate & melts back into magma
Forces magma up to lithosphere surface
Coastal Mountains (Andes), Volcanoes on land, trenches, tsunamis
Continental-Continental one plate subducts underneath other, forcing surface crust upward (mountains)
Ex: Himalayas
Transform Fault Boundary
Plates sliding past each other in opp. directions creates a fault (fracture in rock surface)
Earthquakes = most common activity
Occurs when rough edges of plates get stuck on each other
Pressure builds as plates keep sliding, but edges stay stuck
When stress overcomes the locked fault, plates suddenly release, slide past each other and release energy that shakes the lithosphere
Ring of Fire: pattern of volcanoes all around pacific plate
Offshore island arcs (Japan)
Transform faults: likely location of earthquakes
Hotspots: areas of esp. hot magma rising up to lithosphere
Mid-ocean Islands (iceland, Hawaii)
4.2 Soil Formation & Erosion
Weathering: Breakdown of rocks into smaller pieces
Physical (wind, rain, freezing/thawing of ice)
Biological (roots of trees crack rocks)
Chemical (acid rain, acids from moss/lichen)
Weathering of rocks = soil formation
Broken into smaller and smaller pieces
Carried away and deposited by erosion
Erosion
Transport of weathered rock fragments by wind and rain
Carried to new location and deposited (deposition)
Soil Formation:
Weathering of parent material produces smaller, and smaller fragments that make up geological/inorganic part of soil
Sand, silt, clay
Minerals
From above
Breakdown of organic matter adds humus to soil
Erosion deposits soil particles from other areas, adding to soil
Soil Horizons
O-Horizon: layer of organic matter (plant roots, dead leaves, animal waste, etc) on top of soil
Provides nutrients and limits H2O loss to evap.
A-Horizon: aka topsoil; layer of humus (decomposed organic matter) and minerals from parent material
A-Horizon has most biological activity (earthworms, soil microbes) breaking down organic matter to release nutrients
B-Horizon: aka subsoil; lighter layer below topsoil, mostly made of minerals w/little to no org. matter
Contains some nutrients
C-Horizon: least weathered soil that is closest to the parent material, sometimes called bedrock
Loss of Topsoil: tiling (turning soil for ag.) + loss of vegetation disturb soil and make it more easily eroded by wind and rain
Loss of top soil dries out soil, removes nutrients + soil organisms that recycle nutrients
Compaction: compression of soil by machines (tractors, bulldozers, etc.), grazing livestock, and humans reduces ability to hold moisture
Dry soil erodes more easily
Dry soil supports less plant growth, less root structure, leading to more erosion
Nutrient Depletion: repeatedly growing crops on the same soil removes key nutrients (N, P, K, Na, Mg) over time
Reduces ability to grow future crops
Minimizing erosion of topsoil into surface water:
maintain/plant vegetated buffers between surface waters and crop fields (creates habitats to maintain biodiversity)
Create retention ponds to capture eroded soil (recharges groundwater by slowing flow of runoff and allowing infiltration, maintains biodiversity)
Maintain cover crops on fields after harvests (provides nutrients to next crop)
Use no-till agriculture (reduces fuel requirements, reduces releases of greenhouse gases associated w mechanized agriculture>decreases global climate change)
Soil helps filter and clean water that moves through them
Soil Erosion into bodies of water can create turbidity, reduce the penetration of sunlight (reducing photosynthesis), and clog the gills of aquatic organisms
4.3 Soil Composition & Properties
Soil Particle Size, Texture, and Porosity
Geologic (rock) portion of soil is made up of 3 particles
(biggest to smallest) Sand > silt > clay
Soil Texture: is the % of sand, silt, and clay in a soil
Always adds up to 100% ex: 40-40-20
B/c sand is bigger, it has bigger pores (empty spaces between particles)
This allows air + water to enter sandy soil easily
Clay has smallest pores, so it’s harder for air + water to enter clay-heavy soils
Porosity is the amount of pore space a soil has
more sand in a soil = more porous/higher porosity (easier for water + air to enter)
more clay in a soil = less porous/less porosity (harder for water + air to enter)
Water
Needs to hold water, but not too much
Factors that increase H2O holding cap.
Aerated soil (biological activity)
Compost/humus/organic matter
Clay content
Root structure, especially natives
Factors that decrease H2O holding cap.
Compacted soil (machines, cows)
Topsoil erosion
Sand
Root loss
Nutrients
N, P, K+, Mg2+, Ca+, Na+
Factors that increase soil nutrients
Organic matter (releases nutrients)
Humus (holds and releases nutrients)
Decomposer activity (recycles nut.)
Clay (neg. charge binds pos. nutrients)
Bases (Calcium carbonate - limestone)
Factors that decrease soil nutrients
Acids leach pos. charge nutrients
Excessive rain/irr. leeches nutrients
Excessive farming depletes nut.
Topsoil erosion
Effect on Soil Fertility
Soil that is too sandy (too permeable) drains water too quickly for roots + dries out
Clay-heavy soil doesn’t let H2O drain to roots, or waterlogs (suffocating them)
Ideal soil for most plant growth is loam, which balances porosity or drainage, with H2O holding cap. (40% sand; 40% silt; 20% clay)
4.4 Atmosphere
Nitrogen 78% Mostly in the form of N2 (unuseable to plants without being fixed)
Argon ~ 0.93%: Inert, noble gas
Oxygen ~ 21%: Produced by photosynthesis in plants & needed for human/animal respiration
Water Vapor ~ 0-4%: Varies by region & conditions; acts as a temporary GHG, but less concerning than CO2
CO2 ~ 0.04%: Most important GHG; leads to global warming
Removed from atm. by photosynthesis
Exosphere: Outermost layer where atm. merges with space
Thermosphere: Therm = hottest temp;
absorbs harmful X-rays & UV radiation
charged gas molecules glow under intense solar radiation northern lights (aurora borealis)
Mesosphere: Meso = for middle; 60-80 km, even less dense
Stratosphere: “S” for second - 16-60 km; less dense due to less pressure from layers above
Thickest ozone/O3 layer is found here; absorbs UV-B & UV-C rays which can mutate DNA of animals (cancer)
Troposphere: Tropo = change (weather occurs here) - 0-16 km, most dense due to pressure of other layers above it
Most of atmosphere’s gas molecules are found here
Ozone (O3) in the troposphere is harmful to humans (respiratory irritant) & damages plant stomata, and forms smog
Layers of earth’s atm. are based on where temp. gradients change with distance from earth’s surface
Thermosphere: temp. Increases due to absorption of highly energetic solar radiation
Hottest place on earth (3,100oF)
Mesosphere: temp. decreases because density decreases, leaving fewer molecules to absorb sun
Coldest place on earth (-150oF)
Stratosphere: temp. increases because top layer of stratosphere is warmed by UV rays (like pool surface)
Troposphere: temp. decreases as air gets further from warmth of earth’s surface (temp drops with altitude)
4.5 Global Wind Patterns
4 Properties that determine how air moves
Density: less dense air rises and more dense air sinks
Warm air is LESS (more likely to rise) dense than cool air
As warm air rises from the equator, it condenses and spreads out due to rotation of the earth (A Hadley Cell) (Hadley happens where its hot)
The precipitation from the condensation falls between 0 and 30 N/S latitude creating tropical rainforest
At 30 N/S, the dryer air sinks back down to the surface= deserts
Water Vapor Capacity: how much water vapor can air hold?
Warm air can hold more water vapor
Saturation point: max amount of water vapor air can hold
Temp goes up, saturation point goes up; temp goes down, saturation point goes down
Pressure: as air rises, pressure decreases
Increase in attitude, decrease in pressure, volume increases, temp drops = adiabatic cooling
Pressure and volume inversely proportional
Altitude increases, pressure increases, volume decreases, temp increases = Adiabatic heating
Latent Heat Release: water vapor in the air condenses to form precipitation, to warm up air
Coriolis Effect:
Deflection of objects traveling through the atmosphere due to the spin of earth
Objects are deflected to the RIGHT in the northern hemisphere and to the LEFT in the southern
The spinning of cyclonic storms (counterclockwise in the northern hemisphere and clockwise in the southern)=result of the coriolis effect
Air at 30 degrees moves back to L pressure of equator
West between 0-30 degrees moves from E>W
Because Earth spinning from W>E
Wind between 30-60 movies W>E
Earth spins faster @ 30 degrees than 60
Throw ball from northern hemisphere(moving slower) > equator it moves to the right
Global Wind Patterns
Air moves out from 30 - 0 and 60 due to high pressure @ 30 and low pressure @ 0 and 60
Air rising @ equator = low pressure
Air sinking down at 30 = high pressure
0-30 winds blow E>W (EASTERN TRADE)
Drives ocean current clockwise in N hemisphere, counterclockwise in S hemisphere
30-60 winds blow W>E (WESTERLIES
Drives weather patterns of N America
4.7 Solar Radiation & Earth’s Seasons
isolation : the amount of solar radiation ( energy from sun’s rays) reaching an area
Solar Intensity & Latitude:
Depends on
Angle: how directly rays strike Earth’s surface
The amount of atmosphere sun’s rays pass through
Equator = higher isolation than higher latitudes
At high latitudes, sunlight must pass through more atmosphere & loses more of its energy
A given amount of solar energy is spread over a larger surface areas than at the equator
Solar Intensity & Season
Orbit of earth around sun + tilt on axis changes angle of sun’s rays
Causes varying insolation, varying length of days, and seasons
Tilt of earth’s axis stays fixed during orbit
June/December solstices: N or S hemisphere is maximally tilted toward sun ( summer/winter(
March/Sept equinox: N and S hemispheres equally facing sun
Albedo
The proportion of light that is reflected by a surface
Surfaces with higher albedo reflect more light, and absorb less ( ice/snow)
Absorb less heat
Surfaces with low albedo reflect less light, and absorb more (water)
Absorb more heat
Positive feedback loop>>>
Albedo & Surface Temperature
When sunlight is absorbed by a surface, it gives off infrared radiation (heat)
Areas with lower albedo, absorb more sunlight light/hear
Urban Heat Island: urban areas are hotter than surrounding rural areas due to low albedo blacktop
Polar regions are colder due to high albedo
4.8 Earth’s Geography & Climate
Climate & Geography
Climate is determined by insolation ( latitude>angle of insolation & atmosphere
Higher latitudes receive less insolation ( cooler, less precipitation)
Equator receives most intense insolation ( higher temp, air rises, high precip)
Thermal inversion: cooler air at the surface becomes “trapped” by a later of warmer air above it
Increases intensity of surface air pollution
mountains : disrupt wind, and produce rain shadow effect
Oceans: moderate temp & add moisture to the air
Rain Shadow
A drier area of land next to a higher elevation, higher elevation (such as mtn.) blocks the precipitation from reaching the area
Warm, moist air from ocean hits “windward” side of mts, rises, cools> lush, green vegetation
dry air descends down “leeward” side of mtn, warming as it sinks
Leads to arid dry desert conditions
4.9 El Niño & La Nina
El Nino (southern oscillation- ENSO) is a periodic, non-anthropogenic phenomenon that occurs in the southern pacficic ocean
Changes to patterns of rainfall, wind, ocean circulation occur that can cause climatic/environmental/economic disruptions
Effects: Suppressed upwelling and less productive fisheries in SA; warmer winter in much of N America; decreased hurricane activity in atlantic ocean, increased precip/flooding in americas ( w coast esp)
Effects of LA NINA: stronger upwelling and better fisheries in SA than normal; worse tornado activity in US & hurricane activity in atlantic; rainier/warmer/increased monsoons in SE Asia
Global Ocean Surface Currents
Gyers: large ocean circ. Patterns due to global warming
Clockwise in N hemisphere, counterclockwise in S hemisphere
E>W trade winds between 0-30 push eq. Current E >W
Westerlies between 30-60 degrees and pushes mid lat. currents W>E
Upwelling zones: areas of ocean where winds blow warm surface water away from a land mass, drawing colder/deeper water to replace it
Brings O2 + nutrients to surface = productive fishing
Thermohaline Circulation
Connects all of world’s oceans, mixing salt, nutrients, and temp throughout
War, water from Gulf of MX moves toward North Pole
Cools & Evaporates as it moves towards poles
saltier/colder @ poles , is more dense making it sink
Spreads along ocean floor
Rises back up into shallow warm ocean current @ upwelling zones
5.1 Tragedy of Commons (TOC)
Individuals will used shared/public resources in their own self-interest, degrading them
Overgrazing, overfishing, water/air pollution, overuse of groundwater
Why does it happen?
When no one owns the resource, no one directly suffers the negative consequences of depleting/degrading/or overusing
People assume others will overuse if they don't
No penalty for overusing, degrading, polluting many public resources
Problems?
Overfishing>fishery collapse>population crash(loss of income, starvation)
Air pollution from coal power plants>bronchitis, asthma, increased healthcare costs
Pesticide runoff from farms>contaminates drinking water
Externalities: costs/benefits of a good or service that is not included in the purchase price
Can be + or -
Smell of local bakery= positive externality
Air pollution from a factory= negative externality
How to Solve the TOC
Many economists feel that private ownership or regulation is the solution to the problem of tragedy of the commons
Private land ownership ( individual or gov)
Fees or taxes for use
Permit system for grazing, logging
Taxes, fines, criminal charges for pollution or shared air/soil/water resources
Clean air act, clean water act, safe drinking water act
FRQ: The oceans of the world are often referred to as a commons. Identify one other such commons, explaining how human activities affect that commons, and propose a solution for managing that commons.
Forests are another example of commons in which humans cut down the trees for the purpose of making products or using the empty land for slash-and-burn agriculture to later abandon the area and decrease the stability and biodiversity of the forests/environments. To manage the commons, fees or permits may be imposed with increased security to prevent illegal activities.
5.2 Clearcutting
economically advantageous but>> soil erosion, increased soil/steam temperatures, and flooding
Forest benefits: filtering of air pollutants, removal & storage of CO2 from atm., habitat for organisms
Timber is when it is cut down, lumber is when something is done to the wood
Timber Harvest Practices
Clear-cutting: removing all or almost all the trees in an area
Benefits: most economical, often strands are replanted
Soil Erosion: caused by loss of stabilizing root structure, removed soil organic matter/nutrients from forests, deposits sediments in local streams and makes it more turbid (cloudy)
Reduction of carbon sequestration
Increase in climate change
Increased soil/stream temp: loss of tree shade increases soil temp, loss of tree shade along rivers/streams along with erosion of sediments warms them
Flooding and landslides: logging machinery compacts soil, increased sunlight dries out soil, loss of root structure=erosion of topsoil and o orizon
Decreases H2O holding capacity of soil causing flooding and landslides
Tree Plantations: area where the same tree species are repeatedly planted, grown, and harvested
Lowers biodiversity: mature forests replaced with single species forests; less species/habitat diversity
All the trees planted at same time=all same age; lowers biodiversity b/c no dead trees for woodpeckers, insects, decomposers
Deforestation Consequences
Reduces air filtering and carbon storing services
Cutting trees down releases CO2 from decomposition of leftover organic material
Slash and burn method of clearing land for agriculture by cutting trees/burning releases CO2, N2O, and water vapor into atmosphere (greenhouse gases)
Selective Cutting:
Removal of single trees or small amounts of trees
Optimum growth amount shade-tolerant species
Less erosion, loss of biodiversity, etc
Logging roads
Identify and explain one reasonable cause for a decline in the trout pop of the sophia williams river that is directly linked to the deforestation of the nearby forest
As the deforestation of the nearby forest occurs, the soil starts to loosen with no roots to hold them together making soil erosion and runoff occur more frequently bringing toxins and sediments to the rivers. As this occurs, the fish no longer have a suitable habitat because the increased aquatic particulate that irritates and clogs fish gills and kills the trout
Identify a law that could be applied tho the situation described above
A law that could be the clean water act
Intact forests are an important part of the biosphere. Describe a regulating service forests provide
Regulating services forests provide include water filtration, stabilization of local climate, severe weather mitigation, carbon sink (when trees perform photosynthesis they take in carbon dioxide which becomes a part of their roots and stems), air quality maintenance,, water quality maintenance
Describe TWO ecosystem services provided for humans by forests. Explain how clear-cutting would affect each ecosystem service you describe.
Forests give provisioning services through their wood used as fuel or other human activities- If clear-cutting were to occur, the loss of these goods produced by the forests would cause a shortage of resources. Another ecosystem service forests provide us is as a regulating service as forests are a great sink of carbon from the atmosphere while they regulate and produce oxygen for human use. With clear-cutting, there would be a higher amount of CO2 in the atmosphere (a greenhouse gas) which would lead to higher temperatures and result in the lower amount of CO2 being converted into oxygen for humans to take in.
5.3 The Green Revolution
Shift in agriculture away from small, family operated farms to large, industrial-scale agribusiness
Increased use of mechanization, GMOs, irrigation, fertilizers, pesticides
Increased efficiency of lands, short-term profitability and food supply
Decreased world hunger and increased earth's carrying capacity
negative effects: soil erosion, biodiversity loss, ground or surface water contamination
Mechanization
Increased use of tractors for plowing and filling fields and combines for harvesting=increased yield + profit
Increased reliance on fossil fuels>emits GHG to atmosphere
Heavy machinery also compacts soil, decreasing H2O holding capacity>makes topsoil prone to erosion
Economies of scale: average costs of production fall as output increases
Large upfront expenditure justified by profits from increased production
Small farms cannot expend the up-front cost
Monoculture
Easy to plant, maintain, harvest
Only certain types of pests associated with this one crop
DOWNSIDES: loss of habitat and biodiversity, loss of ancestral varieties, increased pros of catastrophic event
Energy subsidy
Energy input per calorie of food produced
In US: 10 calorie energy input for every 1 calorie you consume
Energy input per calorie of food obtained is greater for modern agriculture practices than for traditional agriculture
Fossil fuel energy is primary energy subsidy for large-scale modern food production (to produce fertilizers/pesticides, to operate tractors, pump water for irrigation, harvest food and prepare for transport)
High-Yield Variety Crops
hybrid/ 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 ( india, pakistan, MX)
GMOs: crops with new genes spliced into their genome
BT bacteria’s pesticide producing material is given to other crops
GMOs
Genetically modified crops have genes for drought tolerance, pest resistance, faster growth, and larger fruit/grain
Increases profitability with few plants lost to drought, disease, or pests + larger plant size + yield/acre
All genetically identical so genetic diversity is decreased and susceptibility to diseases/pests is increased
Synthetic Fertilizer
Shift from organic fertilizers (manure/compost)>synthetic fertilizers (man made ammonium, nitrate, phosphate)
Increases yield/profit w more nutrients needed (N, P, K)
Excess nitrate, phosphate are washed fff fields into nearby waterway>eutrophication/algae blooms
Require ffs for production, releasing CO2
Irrigation
Drawing water from ground or nearby surface water + distributing it on fields = increase plant growth
Makes agriculture more possible in places that are too dry
Can deplete groundwater esp aquifers
Overwatering can drown roots, no O2 access, and cause soil salinization (increase salt level in soils)
Pesticides
Increase in use of synthetic pesticides: chemicals sprayed on crops that kills weeds, insects, rodents, etc that eat or damage crops
Increase yield and profit w few plants lost due to pests
Can wash off crops in runoff and kill or harm non-target species in local soils/waters
Ex. DDT thinned shells of bird eggs, esp eagles
Describe 1 environmental advantage and 1 environmental disadvantage of using GM crops
1 environmental advantage of using GM crops is higher yields per acre and less acreage needed which is a less loss of habitat, biodiversity. 1 environmental disadvantage of using GM crops is that GM crops w insect resistance may impact beneficial insects used for pollination, altered genes may impact human health w altered proteins and toxins
Describe 1 economic advantage and 1 economic disadvantage of using GM crops
1 economic advantage of using GM crops is the increased yield meaning there is an increased profit especially in places that could not grow crops before, reduced water loss that lowers associated costs. 1 economic disadvantage of using GM crops is that higher yields often lead to greater soil depletion, requiring higher costs of mitigation, decreased profit due to use of GM crops that gave increased fertilizer demand to reach yield potential
5.4 Impacts of Agricultural Practices
Arable land- capable of producing crops
Tilling:
Bare soil>soil erosion, evaporation
Eutrophication, need for fertilizer
Turned soil> impacts soil structure
Turned soil>sequestered carbon released as CO2
Eutrophication: overgrowth of algae
Mechanized farming equipment>impact soil, emissions, fossil fuels (habitat loss, water usage to get ff)
Slash and Burn Agriculture
Developing countries
Typically tropical rainforests (low-nutrient soil)
Subsistence (himself and family) farmers
Ash used as fertilizer
UNSUSTAINABLE
Nutrients provided by ash quickly used
Cut down new plot of land 4 crops
IMPACTS: desertification (forests cannot grow back), soil erosion, decreased albedo, increased evaporation, decreased water infiltration
Synthetic vs Organic fertilizers
N, P, K
Organic is from animal waste
Synthetic fertilizers PROS:
Easy to transport/use, timed released, customizable
Synthetic fertilizers CONS:
Water-soluble (runoff), often overused, does nothing to improve soil structure
Organic fertilizer CONS:
Must be gathered, nutrient levels unknown, harder to use
Organic fertilizer PROS:
Can be worked into soil (stays), contains partially digested vegetation>improves soil structure
5.5 Irrigation Methods
furrow irrigation: trench dug along crops and filled with water
Easy, inexpensive and water seeps into soil slowly
66% efficient, 33 lost to runoff and evap
Difficult to apply small amounts
Flood irrigation: flood entire filled, easier but more disruptive to plants
PROS: Easy, inexpensive, mechanization not required
CONS: Requires water nearby, not for all plant types
Can waterlogged soil/drown plants
80% efficient, 20 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 and conserves water
Very expensive, requires mechanization, placements makes any other processes difficult
Most efficient irrigation technique for dry/semiarid climates since less water is lost to evaporation
Used in dry/semiarid climates because water resources are limited and drip uses less water than other methods to reduce water use-l
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 and movement of sprinklers). Mpzz;es can clog ( less sediment in water), machinery run with electricity/FF
Waterlogging
Overwatering can saturate the soil, filling all soil pore space w water
nallow water into pores, so roots cant take in o2 they need
Can stunt growth/kill crops
Solution: Drip irrigation. Soil aeration- poking holes or cores in soil to allow air in and water to drain through soil
Soil Salinization
Salinization process of salt building up in soil over time
Groundwater used for irrigation naturally has small amount of salt
Water evap, salt left behind in soil>dehydrating plant roots and preventing growth
Solution: drip irrigation, soil aeration, flushing w fresh water, switching to freshwater source
Global Human Water Use
Industrial: power plants, metal/plastic manufacturing
Municipal: households ( toilets, shower, drinking water)
Agriculture: water for livestock irrigation water for crops
Aquifers & Groundwater
Groundwater: H2O is stored in pore space of permeable rock and sediment layers
Aquifers: usable groundwater deposits for humans
Replenished by groundwater recharge (rain water percolating down through soil into aquifer)
Unconfined aquifers recharge quickly
Confined aquifer recharge are longer-term water deposits that recharge more slowly
Ogallala aquifer: farmers drawing water from aquifer>water levels losing more than it is being replenished
Depletion of Aquifers
Cone depression: forms when water table is lowered by excessive pumping, depleting water and drying nearby wells
Saltwater intrusion: excessive pumping near coast lowers water table pressure>allowing saltwater to seep deeper into groundwater
FRQ about soil salinization:
Soil salinization occurs when groundwater is used for irrigation and as the water evaporates, salt is left behind in the soil which can become toxic for the plants. A solution to prevent or remediate soil salinization is to switch to a freshwater source in order to flush out the salt and keep using the less salty alternative. But one disadvantage of this solution is that it is very expensive and is not economically profitable to be spending so much on a freshwater resource.
5.6 Pest Control Methods
Pesticide Use and Overuse:
Pesticide treadmill: continuous use of pesticides that increase/stronger concentration and have unintended effects on the environment
Problems
Increasing use> runoff (kills organisms in water, contaminated drinking water); carried by wind to other areas, entry through wells
Killing of bees needed for pollination, biomagnification (storing of persistent of lower trophic level effect on apex predator)
Use
Reduce impacts of pests> maximizing yield of crops, increasing profit not affected by mold, insects etc.
Chemical Control with: pesticides, herbicides, fungicides, rodenticides, insecticides
5.7 Meat Production Methods
Meat overconsumption
When countries are developing they eat more meat
Land Use
Takes a lot of land (25% land on earth)
Animal waste and Emissions
Lots of animals raised for meat>lots of animal waste
Cows emit methane> GHG
Animal Waste
Increase turbidity>>Decrease in aquatic primary productivity, decrease in albedo
Increase in water temperature>>decrease in dissolved oxygen (DO) levels
Increase in organic matter/nutrient load>>increase in decomp by aerobic bacteria, decrease in DO levels, eutrophication
Soil Compaction, soil erosion
Reducing Meat Consumption
Reduce CO2, methane, N2O emissions, conserve water, reduce use of antibiotics and growth hormone, improve topsoil
CAFOs (concentrated animal feeding operation)
CAFOs can raise cattle, chickens, turkeys, pigs, sheep, goats, or any other livestock for consumption by humans
Large but efficient (to serve demand for meat)
Keeps meat production costs down= more affordable meat for consumers
BUT can lead to density-dependnet pathogenic infections; increased nmethane production, and acid-resistant E. coli
Crowded, create a lot of waste^^^ (animal waste section)
Free range grazing
Allows animals to graze on grass during their entire lifecycle
Allows animals to eat grass, the food they are designed to eat
Means less antibiotic use and less antibiotic residue in the meat
Uses animal waste as a natural fertilizer for the forage
Free range grazing and land use>more land area, non native organisms interfering, costs more, not using growth hormone
Requires large areas of land
May lead to overgrazing and land degradation
Leads to higher meat prices for consumer
Overgrazing
5.8 Impacts of Overfishing
Overfishing has led to extreme scarcity of some fish species, which lessens biodiversity in aquatic systems and harm people who depend on fishing for food and commerce
Longline: long line with evenly lined hooks held by flotation devices dragged behind ships (28 mi long)
Pro: efficient (lots of fish w 1 pass),
Con: overfishing if unregulated, non-target species than intended will eat and get hooked
Drift net/gill net: long net set at varying depths pulled by ships/boats (caught by gills)
Pros: efficient
Cons: can lead to overfishing, can catch unintended organisms
Purse seine: massive net that has 2 drawstrings, catch entire school of fish, draw bottom and top shut to draw up fish
Pros: efficient
Cons: can lead to overfishing, can catch unintended organisms
Trawling: net shaped like cone that is dragged through water
Pros: efficient
Cons: can lead to overfishing, can catch unintended organisms, erased DESTROYS HABITAT AS ITS DRAGGED ALONG BOTTOM
Sonar: locating school of fish, seafloor
Pros: more money, fish
Cons: interferes w navigational systems of aquatic mammals like whales
Bycatch: non target species
Processed w rest of everything, tossed back out
Making fishing more sustainable
Catch limits based on MSY (maximum sustainable yield)
Limit age/size of fish caught
Modify techniques to reduce bycatch
laws/treaties that protect critical species: US Endangered Species Act; Convention on International Trade in Endangered Species of Wild Flora and Fauna
Modified fishing techniques: TED is a turtle exclusion device on trawling nets
FRQ: describe commercial practices and explain the role it plays in the depletion of marine organisms
Bottom trawling is when you drag a net or line with hooks along the bottom of the ocean that destroys the benthic habitat and catches many non target species
Sonar uses sound waves to locate fish or see the bottom that allows ships to locate larger school of fish quickly and target them as well as throw off animals using their navigational systems like whales to wash up on the shore
Identify 1 international regulation or US federal law that applied to the harvesting of marine food resources and explain how it helps to manage marine species
Endangered Species Act-
The convention on international trade in endangered species of wild flora and fauna
Identify and explain a way other than passing a law or signing an international treaty, to reduce overfishing of a fish species
Set a catch limit for each commercial fishing company in a country, setting a MSY for an entire country would ensure there will be enough fish to reproduce and replenish fish stocks
Offer incentive to commercial fishing companies and countries that fish sustainable, incentivizing can motivate corporations and countries to shift towards using more sustainable fishing methods
5.10 Impacts of Urbanization
Urban sprawl: change in pop distribution from high pop density areas>low density suburbs that spread into rural lands
Urbanization: shift from lifestyle on agricultural, rural>non agricultural jobs that has high pop density
Pro: mass transit (reduced FF emission), activity level up, more efficient use of space, less land impact
Urban Blighet/Urban Decay: decline in urban neighborhoods due to taxpayers moving out>leads to loss of tax dollars that reduce city services, an increase in abandoned buildings and increase in crime
Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle
Urbanization through the burning of fossil fuels and landfills affects the carbon cycle by increasing the amount of CO2 in the atmosphere
Impermeable surfaces>can’t recharge water/groundwater, runoff
Heat island effect; more veg=cooler temp; less veg=higher temp
FRQ: describe 2 causes of urban sprawl
Transportation: increased use/reliance on automobiles, improved roads, lower gas prices promote driving,
Quality of life: desire for property/yard/lower density, better quality suburban schools
Discuss 2 human health effects associated with urban sprawl;
Increased air pollution: asthma, bronchitis
Less exercise due to auto travel time/commuter diet: obesity, diabetes
Increased driving: personal injuries due to automobile use/crashes
Describe 2 steps a municipality could take to encourage emart growth in order to limit urban sprawl
Transportation: subsidize mass transit to encourage less automobile use
Tax incentives/reduced taxes for living in city
5.11 Ecological Footprints
Ecological footprint: a measure of how many resources a person uses, expressed in an area of land
5 variables: carbon footprint>energy; built-up land>settlements; forests>timber and paper; cropland and pasture>food and fibers; fisheries>seafood
Less developed/developing countries have lower ecological footprint than developed countries
Factors to consider in calculation of ecological footprint: cropland, grazing lands, fishing grounds, forested areas, built-up (urbanized) lands, carbon demand
5.12 Introduction to Sustainability
Sustainability refers to humans living on Earth and their use of resources without depletion of the resources for future generations
Indicators: biological diversity, food production, average global surface temp, CO2 concentrations, human pop, and resource depletion rates
Biological diversity> healthier ecosystems are resistant to disturbances
Food production> poor practices lead to soil degradation and water pollution
Global surface temp and CO2 concentrations>excessive CO2 increases global temp creating climate change
Human pop> exponential growth stresses the planet
Resource depletion> will this resource be available in the future
Sustainable Yield: The amount of a renewable resource that can be taken without reducing the available supply (50% of carrying capacity)
5.13 Methods to Reduce Urban Runoff
Consequences of urban runoff
Decreased infiltration (groundwater recharge) from impervious surfaces
Rain washes pollutants into storm drains and & local surface waters
Pollutants & effects:
Salt (plant/insect death)
Sediment (turbidity)
Fertilizer (eutrophication)
Pesticides
Oil & gas (suffocate fish/kill aq insects)
Solution: Permeable Pavement
Specifically designed to allow stormwater to infiltrate & exchange ground water
Decreases runoff, decreasing pollutants carried into storm drains & into local surface water
Decreases likelihood of flossing during heavy rainfall
More costly
Solution: rain garden
Garden planted in urban areas, especially surrounding a storm drain
Decreases runoff by allowing it to soak into garden soil surrounding storm drain
Creates hab for pollinators
Solution: public transit
More cars on road= more pollutants on streets to runoff into storm drains and local waters
More cars=more lands and parking lot (impervious surfaces) and more stormwater runoff
Public transit decreases urban runoff, pollutants on road, CO2 emissions and
Solution: Building Up, not Out
Building vertically decreases impervious surfaces (decreasing urban runoff)
Can be combined with green roof or rooftop garden to further decrease runoff
Sequesters co2 and filters air pollutants
Plants absorb
5.14 Integrated Pest Management (IPM)
A combination of methods used to effectively control pest species while minimizing the disruption of the environment
Goal is to reduce the amount of chemical pesticides used to reduce the pesticide treadmill and poisoning of non-target species and humans
Biological controls: introduction of natural pest predators
Physical controls: barriers that protect crops
Chemical controls: poisons that kill pest species
Crop Rotation: switching crops in harvests
Intercropping: cultivation of 2+ crops grown at same time (2 pests w common predator)
By switch crops, pest species many not accumulate that warrant pesticide use
THE USE OF CHEMICAL PESTICIDES CAN CAUSE HARM 2 ENVIRONMENT (kills non-targets wildlife, contaminates water supplies, affects human health)
IPM PROS:
Decreases amount of chemical pesticides sprayed on crops, economic savings, sustainable, targeted, minimizes loss of pollinators, minimize health risk, decreases pesticide resistance
IPM DRAWBACKS:
Complex, slow, expensive
The use of IPM reduces the risk that pesticides pose to wildlife, water supplies, and human health
IPM mimizies disruptions to the environment and threats to human health BUT is complex and expensive
5.15 Sustainable Agriculture
Preservation of soil is essential to maintaining sustainable food production practices
Contour Plowing: Preserved natural topography of the land and leaves oil intact (less soil erosion)
Windbreaks (adding trees): Reduces wind erosion that may blow soil away
Strip cropping: Harvesting one crop at a different time will leave one crop holding the soil in place
Terracing: hill or mountain; decreases the velocity of water going downhill>>reducing soil erosion
No till agriculture: leave soil in place and does not loosen it so it can resist erosion
Perennial crops: crop roots hold soil together year-round, does not have to be replanted
Practices that improve soil fertility include:
Crop rotation: may replenish soils of nutrients naturally (ex. Legumes add nitrogen to the soil)
Green manure: adds bulk and Nitrogen, Phosphorus, Potassium to soil that slowly decomposes
Limestone: addition of limestone adds valuable calcium to soil and increases pH making soils more alkaline
Overgrazing is unsustainable in food production
Overgrazing: extensive grazing that causes damage to plants (leads to soil erosion and destruction of pasturable fields)
Rotational Grazing: the cycling of livestock around a particular part of their pasture to not overgraze 1 area (allows the cover crop to replenish and hold soil in place)
FRQ: describe 1 agricultural practice that can lead to the degradation of agricultural land
plowing/tilling the soil increases soil erosion (by breaking up the soil structure) and reduces fertility
Using monocultures or the growing of 1 crops over and over again will deplete the soil of the needed nutrients
Overgrazing by livestock leads to a loss of soil cover and increases soil erosion without the top cover to hold it in place
Describe a potential solution or technique that can prevent or reduce degradation of agricultural land
Contour plowing uses the contours of the land to minimize soil erosion
Terracing, growing crops on side of hills or mountains in a series of steps reduces soil erosion
Perennial crops remain in the soil year-round and can survive for several years which reduces the need for replanting and improving or disturbing the structure of the soil which limits soil erosion
5.16 Aquaculture
Aquaculture: the farming of fish, shellfish, mollusks, crustaceans or aquatic plants by an individual or corporation with the intent to sell the farmned organisms to consumers for profit
Can occur in both marine and freshwater environments, depending on organism farmers
China is leader in aquaculture production in marine and freshwater environments
Aquaculture has expanded b/c it is highly efficient, requires only small areas of water, requires little fossil fuel inputs
AQUACULTURES HELPS REDUCE OVERFISHING AND PROVIDES AFFORDABLE, HIGH-QUALITY PROTEIN TO HUMANS EFFECIENTLY AND W LESS FOSSIL FUEL INPUTS
CONS: can waste from organisms/uneaten food pellets can contaminate waterways and fish that escape may compete or breed w wild fish
Density of fish in aquacultures can lead to disease incidence which can be transmitted to wild fish
Aquaculture as an environmental solution:
Advantages: provides high-quality protein to growing human pop; provides stable income to fisherfolk w less risk than open-water; less acreage and less water; fewer fossil fuel input needed than terrestrial agriculture
Disadvantages: nitrogenous waste can pollute waterways>>eutrophication; Uneaten feed can pollute waterways>water-quality issues; escaped farmed organisms can interbreed or compete w wild organisms; diseases/parasites from densely packed farned pop can spread to wild; medication to control disease in farmed can pollute waterways
FRQ: describe an advantage of aquaculture that helps minimize natural resource use
Less water, less fossil fuel inputs (minimizes natural resource use)
Identify a disadvantage of aquaculture and describe how that disadvantage might lead to an unintended environmental consequence
Escape of farmed organisms can lead to competition and change to the wild organisms due to competition and interbreeding (foodweb change, diversity)
5.17 Sustainable Forestry
Forest ecosystem services: food, medicine, fuel, fiber, timer, carbon sequestration, air purification, water purification, flood and erosion control, maintenance of biodiversity, recreation, aesthetic and cultural value
Sustainable forestry: refers to a collection of methods that attempt to reduce the human impact of harvesting trees and using forest resources
Methods for mitigating deforestation
Reforestation: intentional restocking of existing forests/woodlands that have been depleted
Using and buying wood harvested by ecologically sustainable forestry techniques:
Selective harvesting of trees, prohibiting logging in ecologically sensitive or highly biodiverse areas of forested land, transportation of felled trees via techniques that lessen ecological disruption and soil compaction
Reusing/repurposing/recycling wood
Methods to protect forests from pathogens and insects include:
Integrated Pest management (IPM): continual monitoring of health of tree stands, thinning of underbush, knowledge of common pest species, understanding economic pest threshold, setting pest traps/manual weeding, biological control w natural predators, chemical control w repellents/pesticides/herbicides (last resort)
Removal of affected trees: helps slow spread of infestations in a stand
Prescribed burn: method by which forests are set on fire under controlled conditions to reduce the occurrence of natural fires
Fire removes excess understory plants, dead tree limbs, needles, branches
Selective removal can reduce severity of natural forest fires by reducing the amount of dry matter available as fuel/help reduce pest infestations
Sustainable forestry methods
Increase the economic costs of using forest resources and reduce profit margins for timber companies
Require forestry workers to be trained on how to properly use these techniques
PRO of mitigation of deforestation: preserves biodiversity, preserved critical ecosystems services that forests provide, economically supports organizations and timber companies that employ sustainable methods, reusing wood reduced need to cut new timber
PRO of using IPM/selective tree removal for pest management: ensures forestry workers are closely monitoring tree stands; reduces impact of pesticide/herbicide use on non-target species, soil, water; reduces likelihood of trophic structure disruption from pest eradication; more closely mimics natural balance of ecosystem
PRO of prescribed burns: lessen the severity of naturally-occurring fires by removing underbrush and debris; encourage new growth of nntaive species; help manage pest species
FRQ: provide 1 reason why fire-suppression policies lead to increased beetle activity
Fire-suppression means that the undergrowth is not burned where pests usually breed
When the pest accumulate in the undergrowth, it affects the mature trees more>and in a forest that is not allowed to burn, there are more mature trees
Explain how prescribed burns might mitigate the impact of mountain pine beetles on forests
Prescribed burns would burn the understory in a forest that would reduce pest populations
Help clear understory so that smaller saplings can come up which will make a mix of tree growth and not a majority of large trees that are preferred by the beetles
A national forest service intern recommends using a combination of IPM methods and selective tree removal to reduce beetle pop>>>
Explain 2 advantages of this approach that would justify its use by the forest service for beetle control
It reduces the effect of chemical pesticides on nontarget species
Selective tree removal means keeping the biodiversity of the forest intact b/c only diseased trees are removed
1 MBTU= 1,000,000 BTU
6.1 Renewable vs Nonrenewable Energy Sources
Nonrenewable energy sources are in a fixed amount and involve energy transformation that cannot be easily replaced
Fossil fuels: fossilized remains of ancient biomass that take millions of years to form
Coal, oil, natural gas
Nuclear: energy generated from uranium or other radioactive fuels
Renewable energy sources are those that can be replenished naturally, at or near the rate of consumption, and rescued
Depletable renewables can run out if overused (biomass)
Nondepletable renewables do not run out if overused (solar, wind hydroelectric, )
Fossil fuels
Derived from biological material that fossilized millions of years ago
Form in anaerobic conditions (swamps)
oil/gas trapped in rocks
Renewable Energy
Rate of consumption:
Rate of use must be at or below rate of regeneration for renewables
Fossil fuels will run out because they take far longer to regenerate than the rate we use them
FRQ: explain whether or not biomass is a renewable energy source + justify
Biomass is a renewable energy source because it can be replenished naturally at a rate near consumption but can be depletable and run out if overused
Non-renewable energy resources – Resources that have a finite amount available on Earth for human use.
Non-depletable resources – Resources that cannot be used up on a human time scale.
Potentially renewable resources – A resource that can be sustained on Earth as long as consumption does not outpace growth/replenishment.
Renewable resources – Broad category for non-depletable and potentially renewable resources.
Potential energy is stored energy and includes chemical, nuclear, gravitational, or mechanical energy.
Kinetic energy is energy created from movement and includes radiant energy, thermal energy, sound, motion and electrical energy.
AP Environmental Science Course Review Part 2
Evolution
Genetic changes in a population of species overtime
Adaptation: inherited traits that helps an organism better survive
Natural selection: some organisms are better able to survive and reproduce than others
Coevolution: 2 populations of species influence each others evolution over a long period of time
Poisonous newt + poison-resistant snake
Mutations: genetic changes in DNA that occur randomly and can encourage evolution
Types of Selection
Speciation
When a population ends up breaking into 2 populations in some way
Allopatric speciation: species are separated by a physical barrier and cannot cross-breed, leading to independent evolution and speciation
Sympatric: species are NOT separated but changes in behavior leads to lack of mating and eventual speciation
Types of Species
Indicator: alters us to changes in the environment earlier than either species due to their sensitivity to changes (ex. frogs)
Foundation: alters the environment in a way that influences other species (ex. Elephants that push trees, create paths in savanna)
Keystone: species that exert a large influence over an ecosystem and is dependent on by many other species (ex. otters)
Generalist species: occupy broad niches, eat a variety of food, can withstand varying conditions (ex. mice)
Specialist species: occupy specific narrow niches often with species food sources, sensitive to changes and more prone to extinction should conditions change (ex. koala)
Primary VS. Secondary Succession
Primary Succession | Secondary Succession |
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Intermediate disturbance hypothesis: Ecosystems can withstand a moderate amount of disturbance and it often increases biodiversity more than a low/high amount of disturbance
A high amount of disturbance>> extinctions
Biodiversity
Higher biodiversity = higher ecosystem/population resilience to disturbance
Species diversity: number and variety of species contained in a habitat
Species richness: number of species specifically
Species evenness: refers to whether or not species are in equal abundance
A rainforest would have high species evenness (lots of species + not one dominates)
Pine forest has low species evenness (pine trees are majority in ecosystem)
Island Biodiversity
Larger islands have greater biodiversity than smaller islands as do islands that are closer to the mainland
Larger islands have higher rates of migration of NEW species from the mainland as do closer islands than smaller islands and islands away
Range of Tolerance
Different types of changes in the ecosystems that an organism can withstand
Optimum range doesn't affect them
high/low= physiological stress or death (having to do w salinity, temp, DO, pH, etc)
Life Strategies
R-Selected | K-Selected |
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Growth Patterns
Population growth is limited by resource availability
Resources are always finite
When resources are abundant, population growth increase
When resources are scarce, unequal distribution may result in increased mortality + decreased fecundity (ability to produce new offspring)
Overshoot: refers to when a pop exceeds the carrying capacity of an ecosystem
Can result in environmental consequences such as resource degradation or dieback of population
Logistic Growth
As population approach limits on food/water/resources; carrying capacity (K) slows down pop growth
After approaching K, they'll be around stable
Exponential Growth
A lot of pop experiences early in their population
No limits on food/resources
Carrying Capacity: the maximum number of individuals the habitat can support based on food, water, and other resources (density-dependent factors)
Carrying capacity can change as available resources change
If populations overshoot carrying capacity, the lack of resources will result in a decline in pop #
Survivorship Curves
Type 1: longer lives, most make it to maturity, low infant deaths, less offspring produced, higher parental vcare
Ex. People, k-selected species
Increasing mortality with age
Type 2: equal chance of dying at any point in life
Ex. birds
Type 3: high infant deaths, those that do make it usually survive to adulthood, offspring often over-produced
R-selected species
Age Structures
Rapid growth:
wide pyramid with wide base (lots of younger individuals and likely lots of future growth)
Top is skinny: little access to medical care
Slow growth:
Lots of older individuals>loner life span and increased access to medical care
Zero growth:
Rectangular shaped; TFR is at replacement level (2.1)
Negative growth/decline
Total Fertility Rate
TFR: the numbers of babies on average that women in a country have (ages 15-45)
Replacement fertility: 2.1 (replaces mom and dad), leads to population stabilization
Higher TFR in less developed countries, lower TFR in more developed countries
Factors affecting TFR: medical care, jobs for women, death (infant), literacy in women, labor (needed for child labor), birth control access, government policies/laws
Population Math/Calculations
Population growth rate= (birth rate + immigration) - (death rate + emigration)/total pop) x 100
Doubling Time= 70/r; r=growth rate
Birth rate (as a %): (total births/total population) x 100
Crude birth rate (per 1,000)= (total births/total population) x 1000
Death Rate (as a %): (total deaths/total population) x 100
Crude Death rate (per 1,000)= (total deaths/total population) x 1000
Global population growth rate (r) = (CBR/1000-CDR/100) x 100
National population growth rate (r) - ((CBR+immigration)-(CDR+emigration))/10
Percent rate of change: (new-old)/(old) x 100
Demographic Transition Model
Characteristics of developing countries:
Higher infant mortality rates
More children in workforce
Lower life- expectancy
Lower rates of access to modern medicine, education, safe drinking water, and sanitation
Stage 1 Pre-industrial: high BR and DR
Ex. not good living condition, struggling economy, war-torn country
agrarian/agricultural (more children=financial benefit from farms)
Stage 2 Transitioning: dropping DR, still high BR
Life span begins to increase
Rapid pop growth
Stage 3 Industrial: low DR, declining BR
Pop growth begins to slow down
Increased education/opportunities increases age of first pregnancy decreasing # of children born per woman, more children=financial burden; increased average ay m marriage, increased access to contraception + family planning
Stage 4 Post-industrial: BR approaching DR
TFR may fall below RLF
Pop growth may be near 0, or negative
Human population growth (or decline) in a geographic area is influenced by:
Birth rates, infant mortality rates, death rates, access to family planning, access to education, age at marriage
Globally, human population growth is limited by:
Earth’s carrying capacity, food supply (population growth tends to grow exponentially but food supplies grow linearly- Malthusian’s theory)
Population growth can be affected by density-dependent or density-independent
Density dependent: factors affect a population more as the population size increases
Access to clean water, access to clean air, availability of food resoeces, disease transmission, territory size
Density-independent: factors that affect a population at the same rate, no matter what the population size
Major storms (hurricanes, tornadoes, tsunamis, etc); fires; prolonged heat waves; doughts
4.1 Plate Tectonics
Plate Tectonics: Theory explaining the movement of the Earth’s rigid lithospheric plates is the result of convection processes in the underlying partially molten mantle
Earth’s Structure
Core: Dense mass of solid nickel, iron, and radioactive elements that release heat
Mantle: liquid layer of magma surrounding the core, kept liquefied by intense heat from core
Asthenosphere: solid, flexible layer of mantle, beneath the lithosphere
Lithosphere: thin, brittle layer of rock floating on top of mantle ( broken up into tectonic plates
Crust: very outer layer of the lithosphere, Earth’s surface
Plate Boundaries
Divergent Plate Boundary: Plates move away from each other
Rising magma plume from mantle forces plates apart
Forms: mid-oceanic ridges, volcanoes, seafloor spreading, and rift valleys (on land)
Convergent Plate Boundary:Plates move towards each other
Leads to subduction (one plate being forced beneath another)
Forms: mountains, island arcs, earthquakes, and volcanoes
Transform fault Plate Boundary: plates slide past each other in opposite directions
Forms: earthquakes (occurs when the stress on lithospheric plates overcomes a locked fault, resulting in a release of energy)
Convection Cycles (Divergent): Magma heated by earth’s core rises towards lithosphere
Rising magma cools & expands, forcing oceanic plates apart
Creates, mid ocean ridges, volcanoes, spreading zones or “seafloor spreading”
Magma cools, and solidifies into new lithosphere
Magma heated by earth’s core rises towards lithosphere
Rising magma cools & expands, forcing oceanic plates apart
Creates, mid ocean ridges, volcanoes, spreading zones or “seafloor spreading”
Magma cools, and solidifies into new lithosphere
Convergent Boundary - Subduction Zone
Oceanic-Oceanic : one plate subducts underneath other
Forces magma up to lithosphere surface, forming mid ocean volcanoes
Island arcs
Off-shore trench
Oceanic-Continental : dense oceanic plate subducts beneath cont. Plate & melts back into magma
Forces magma up to lithosphere surface
Coastal Mountains (Andes), Volcanoes on land, trenches, tsunamis
Continental-Continental one plate subducts underneath other, forcing surface crust upward (mountains)
Ex: Himalayas
Transform Fault Boundary
Plates sliding past each other in opp. directions creates a fault (fracture in rock surface)
Earthquakes = most common activity
Occurs when rough edges of plates get stuck on each other
Pressure builds as plates keep sliding, but edges stay stuck
When stress overcomes the locked fault, plates suddenly release, slide past each other and release energy that shakes the lithosphere
Ring of Fire: pattern of volcanoes all around pacific plate
Offshore island arcs (Japan)
Transform faults: likely location of earthquakes
Hotspots: areas of esp. hot magma rising up to lithosphere
Mid-ocean Islands (iceland, Hawaii)
4.2 Soil Formation & Erosion
Weathering: Breakdown of rocks into smaller pieces
Physical (wind, rain, freezing/thawing of ice)
Biological (roots of trees crack rocks)
Chemical (acid rain, acids from moss/lichen)
Weathering of rocks = soil formation
Broken into smaller and smaller pieces
Carried away and deposited by erosion
Erosion
Transport of weathered rock fragments by wind and rain
Carried to new location and deposited (deposition)
Soil Formation:
Weathering of parent material produces smaller, and smaller fragments that make up geological/inorganic part of soil
Sand, silt, clay
Minerals
From above
Breakdown of organic matter adds humus to soil
Erosion deposits soil particles from other areas, adding to soil
Soil Horizons
O-Horizon: layer of organic matter (plant roots, dead leaves, animal waste, etc) on top of soil
Provides nutrients and limits H2O loss to evap.
A-Horizon: aka topsoil; layer of humus (decomposed organic matter) and minerals from parent material
A-Horizon has most biological activity (earthworms, soil microbes) breaking down organic matter to release nutrients
B-Horizon: aka subsoil; lighter layer below topsoil, mostly made of minerals w/little to no org. matter
Contains some nutrients
C-Horizon: least weathered soil that is closest to the parent material, sometimes called bedrock
Loss of Topsoil: tiling (turning soil for ag.) + loss of vegetation disturb soil and make it more easily eroded by wind and rain
Loss of top soil dries out soil, removes nutrients + soil organisms that recycle nutrients
Compaction: compression of soil by machines (tractors, bulldozers, etc.), grazing livestock, and humans reduces ability to hold moisture
Dry soil erodes more easily
Dry soil supports less plant growth, less root structure, leading to more erosion
Nutrient Depletion: repeatedly growing crops on the same soil removes key nutrients (N, P, K, Na, Mg) over time
Reduces ability to grow future crops
Minimizing erosion of topsoil into surface water:
maintain/plant vegetated buffers between surface waters and crop fields (creates habitats to maintain biodiversity)
Create retention ponds to capture eroded soil (recharges groundwater by slowing flow of runoff and allowing infiltration, maintains biodiversity)
Maintain cover crops on fields after harvests (provides nutrients to next crop)
Use no-till agriculture (reduces fuel requirements, reduces releases of greenhouse gases associated w mechanized agriculture>decreases global climate change)
Soil helps filter and clean water that moves through them
Soil Erosion into bodies of water can create turbidity, reduce the penetration of sunlight (reducing photosynthesis), and clog the gills of aquatic organisms
4.3 Soil Composition & Properties
Soil Particle Size, Texture, and Porosity
Geologic (rock) portion of soil is made up of 3 particles
(biggest to smallest) Sand > silt > clay
Soil Texture: is the % of sand, silt, and clay in a soil
Always adds up to 100% ex: 40-40-20
B/c sand is bigger, it has bigger pores (empty spaces between particles)
This allows air + water to enter sandy soil easily
Clay has smallest pores, so it’s harder for air + water to enter clay-heavy soils
Porosity is the amount of pore space a soil has
more sand in a soil = more porous/higher porosity (easier for water + air to enter)
more clay in a soil = less porous/less porosity (harder for water + air to enter)
Water
Needs to hold water, but not too much
Factors that increase H2O holding cap.
Aerated soil (biological activity)
Compost/humus/organic matter
Clay content
Root structure, especially natives
Factors that decrease H2O holding cap.
Compacted soil (machines, cows)
Topsoil erosion
Sand
Root loss
Nutrients
N, P, K+, Mg2+, Ca+, Na+
Factors that increase soil nutrients
Organic matter (releases nutrients)
Humus (holds and releases nutrients)
Decomposer activity (recycles nut.)
Clay (neg. charge binds pos. nutrients)
Bases (Calcium carbonate - limestone)
Factors that decrease soil nutrients
Acids leach pos. charge nutrients
Excessive rain/irr. leeches nutrients
Excessive farming depletes nut.
Topsoil erosion
Effect on Soil Fertility
Soil that is too sandy (too permeable) drains water too quickly for roots + dries out
Clay-heavy soil doesn’t let H2O drain to roots, or waterlogs (suffocating them)
Ideal soil for most plant growth is loam, which balances porosity or drainage, with H2O holding cap. (40% sand; 40% silt; 20% clay)
4.4 Atmosphere
Nitrogen 78% Mostly in the form of N2 (unuseable to plants without being fixed)
Argon ~ 0.93%: Inert, noble gas
Oxygen ~ 21%: Produced by photosynthesis in plants & needed for human/animal respiration
Water Vapor ~ 0-4%: Varies by region & conditions; acts as a temporary GHG, but less concerning than CO2
CO2 ~ 0.04%: Most important GHG; leads to global warming
Removed from atm. by photosynthesis
Exosphere: Outermost layer where atm. merges with space
Thermosphere: Therm = hottest temp;
absorbs harmful X-rays & UV radiation
charged gas molecules glow under intense solar radiation northern lights (aurora borealis)
Mesosphere: Meso = for middle; 60-80 km, even less dense
Stratosphere: “S” for second - 16-60 km; less dense due to less pressure from layers above
Thickest ozone/O3 layer is found here; absorbs UV-B & UV-C rays which can mutate DNA of animals (cancer)
Troposphere: Tropo = change (weather occurs here) - 0-16 km, most dense due to pressure of other layers above it
Most of atmosphere’s gas molecules are found here
Ozone (O3) in the troposphere is harmful to humans (respiratory irritant) & damages plant stomata, and forms smog
Layers of earth’s atm. are based on where temp. gradients change with distance from earth’s surface
Thermosphere: temp. Increases due to absorption of highly energetic solar radiation
Hottest place on earth (3,100oF)
Mesosphere: temp. decreases because density decreases, leaving fewer molecules to absorb sun
Coldest place on earth (-150oF)
Stratosphere: temp. increases because top layer of stratosphere is warmed by UV rays (like pool surface)
Troposphere: temp. decreases as air gets further from warmth of earth’s surface (temp drops with altitude)
4.5 Global Wind Patterns
4 Properties that determine how air moves
Density: less dense air rises and more dense air sinks
Warm air is LESS (more likely to rise) dense than cool air
As warm air rises from the equator, it condenses and spreads out due to rotation of the earth (A Hadley Cell) (Hadley happens where its hot)
The precipitation from the condensation falls between 0 and 30 N/S latitude creating tropical rainforest
At 30 N/S, the dryer air sinks back down to the surface= deserts
Water Vapor Capacity: how much water vapor can air hold?
Warm air can hold more water vapor
Saturation point: max amount of water vapor air can hold
Temp goes up, saturation point goes up; temp goes down, saturation point goes down
Pressure: as air rises, pressure decreases
Increase in attitude, decrease in pressure, volume increases, temp drops = adiabatic cooling
Pressure and volume inversely proportional
Altitude increases, pressure increases, volume decreases, temp increases = Adiabatic heating
Latent Heat Release: water vapor in the air condenses to form precipitation, to warm up air
Coriolis Effect:
Deflection of objects traveling through the atmosphere due to the spin of earth
Objects are deflected to the RIGHT in the northern hemisphere and to the LEFT in the southern
The spinning of cyclonic storms (counterclockwise in the northern hemisphere and clockwise in the southern)=result of the coriolis effect
Air at 30 degrees moves back to L pressure of equator
West between 0-30 degrees moves from E>W
Because Earth spinning from W>E
Wind between 30-60 movies W>E
Earth spins faster @ 30 degrees than 60
Throw ball from northern hemisphere(moving slower) > equator it moves to the right
Global Wind Patterns
Air moves out from 30 - 0 and 60 due to high pressure @ 30 and low pressure @ 0 and 60
Air rising @ equator = low pressure
Air sinking down at 30 = high pressure
0-30 winds blow E>W (EASTERN TRADE)
Drives ocean current clockwise in N hemisphere, counterclockwise in S hemisphere
30-60 winds blow W>E (WESTERLIES
Drives weather patterns of N America
4.7 Solar Radiation & Earth’s Seasons
isolation : the amount of solar radiation ( energy from sun’s rays) reaching an area
Solar Intensity & Latitude:
Depends on
Angle: how directly rays strike Earth’s surface
The amount of atmosphere sun’s rays pass through
Equator = higher isolation than higher latitudes
At high latitudes, sunlight must pass through more atmosphere & loses more of its energy
A given amount of solar energy is spread over a larger surface areas than at the equator
Solar Intensity & Season
Orbit of earth around sun + tilt on axis changes angle of sun’s rays
Causes varying insolation, varying length of days, and seasons
Tilt of earth’s axis stays fixed during orbit
June/December solstices: N or S hemisphere is maximally tilted toward sun ( summer/winter(
March/Sept equinox: N and S hemispheres equally facing sun
Albedo
The proportion of light that is reflected by a surface
Surfaces with higher albedo reflect more light, and absorb less ( ice/snow)
Absorb less heat
Surfaces with low albedo reflect less light, and absorb more (water)
Absorb more heat
Positive feedback loop>>>
Albedo & Surface Temperature
When sunlight is absorbed by a surface, it gives off infrared radiation (heat)
Areas with lower albedo, absorb more sunlight light/hear
Urban Heat Island: urban areas are hotter than surrounding rural areas due to low albedo blacktop
Polar regions are colder due to high albedo
4.8 Earth’s Geography & Climate
Climate & Geography
Climate is determined by insolation ( latitude>angle of insolation & atmosphere
Higher latitudes receive less insolation ( cooler, less precipitation)
Equator receives most intense insolation ( higher temp, air rises, high precip)
Thermal inversion: cooler air at the surface becomes “trapped” by a later of warmer air above it
Increases intensity of surface air pollution
mountains : disrupt wind, and produce rain shadow effect
Oceans: moderate temp & add moisture to the air
Rain Shadow
A drier area of land next to a higher elevation, higher elevation (such as mtn.) blocks the precipitation from reaching the area
Warm, moist air from ocean hits “windward” side of mts, rises, cools> lush, green vegetation
dry air descends down “leeward” side of mtn, warming as it sinks
Leads to arid dry desert conditions
4.9 El Niño & La Nina
El Nino (southern oscillation- ENSO) is a periodic, non-anthropogenic phenomenon that occurs in the southern pacficic ocean
Changes to patterns of rainfall, wind, ocean circulation occur that can cause climatic/environmental/economic disruptions
Effects: Suppressed upwelling and less productive fisheries in SA; warmer winter in much of N America; decreased hurricane activity in atlantic ocean, increased precip/flooding in americas ( w coast esp)
Effects of LA NINA: stronger upwelling and better fisheries in SA than normal; worse tornado activity in US & hurricane activity in atlantic; rainier/warmer/increased monsoons in SE Asia
Global Ocean Surface Currents
Gyers: large ocean circ. Patterns due to global warming
Clockwise in N hemisphere, counterclockwise in S hemisphere
E>W trade winds between 0-30 push eq. Current E >W
Westerlies between 30-60 degrees and pushes mid lat. currents W>E
Upwelling zones: areas of ocean where winds blow warm surface water away from a land mass, drawing colder/deeper water to replace it
Brings O2 + nutrients to surface = productive fishing
Thermohaline Circulation
Connects all of world’s oceans, mixing salt, nutrients, and temp throughout
War, water from Gulf of MX moves toward North Pole
Cools & Evaporates as it moves towards poles
saltier/colder @ poles , is more dense making it sink
Spreads along ocean floor
Rises back up into shallow warm ocean current @ upwelling zones
5.1 Tragedy of Commons (TOC)
Individuals will used shared/public resources in their own self-interest, degrading them
Overgrazing, overfishing, water/air pollution, overuse of groundwater
Why does it happen?
When no one owns the resource, no one directly suffers the negative consequences of depleting/degrading/or overusing
People assume others will overuse if they don't
No penalty for overusing, degrading, polluting many public resources
Problems?
Overfishing>fishery collapse>population crash(loss of income, starvation)
Air pollution from coal power plants>bronchitis, asthma, increased healthcare costs
Pesticide runoff from farms>contaminates drinking water
Externalities: costs/benefits of a good or service that is not included in the purchase price
Can be + or -
Smell of local bakery= positive externality
Air pollution from a factory= negative externality
How to Solve the TOC
Many economists feel that private ownership or regulation is the solution to the problem of tragedy of the commons
Private land ownership ( individual or gov)
Fees or taxes for use
Permit system for grazing, logging
Taxes, fines, criminal charges for pollution or shared air/soil/water resources
Clean air act, clean water act, safe drinking water act
FRQ: The oceans of the world are often referred to as a commons. Identify one other such commons, explaining how human activities affect that commons, and propose a solution for managing that commons.
Forests are another example of commons in which humans cut down the trees for the purpose of making products or using the empty land for slash-and-burn agriculture to later abandon the area and decrease the stability and biodiversity of the forests/environments. To manage the commons, fees or permits may be imposed with increased security to prevent illegal activities.
5.2 Clearcutting
economically advantageous but>> soil erosion, increased soil/steam temperatures, and flooding
Forest benefits: filtering of air pollutants, removal & storage of CO2 from atm., habitat for organisms
Timber is when it is cut down, lumber is when something is done to the wood
Timber Harvest Practices
Clear-cutting: removing all or almost all the trees in an area
Benefits: most economical, often strands are replanted
Soil Erosion: caused by loss of stabilizing root structure, removed soil organic matter/nutrients from forests, deposits sediments in local streams and makes it more turbid (cloudy)
Reduction of carbon sequestration
Increase in climate change
Increased soil/stream temp: loss of tree shade increases soil temp, loss of tree shade along rivers/streams along with erosion of sediments warms them
Flooding and landslides: logging machinery compacts soil, increased sunlight dries out soil, loss of root structure=erosion of topsoil and o orizon
Decreases H2O holding capacity of soil causing flooding and landslides
Tree Plantations: area where the same tree species are repeatedly planted, grown, and harvested
Lowers biodiversity: mature forests replaced with single species forests; less species/habitat diversity
All the trees planted at same time=all same age; lowers biodiversity b/c no dead trees for woodpeckers, insects, decomposers
Deforestation Consequences
Reduces air filtering and carbon storing services
Cutting trees down releases CO2 from decomposition of leftover organic material
Slash and burn method of clearing land for agriculture by cutting trees/burning releases CO2, N2O, and water vapor into atmosphere (greenhouse gases)
Selective Cutting:
Removal of single trees or small amounts of trees
Optimum growth amount shade-tolerant species
Less erosion, loss of biodiversity, etc
Logging roads
Identify and explain one reasonable cause for a decline in the trout pop of the sophia williams river that is directly linked to the deforestation of the nearby forest
As the deforestation of the nearby forest occurs, the soil starts to loosen with no roots to hold them together making soil erosion and runoff occur more frequently bringing toxins and sediments to the rivers. As this occurs, the fish no longer have a suitable habitat because the increased aquatic particulate that irritates and clogs fish gills and kills the trout
Identify a law that could be applied tho the situation described above
A law that could be the clean water act
Intact forests are an important part of the biosphere. Describe a regulating service forests provide
Regulating services forests provide include water filtration, stabilization of local climate, severe weather mitigation, carbon sink (when trees perform photosynthesis they take in carbon dioxide which becomes a part of their roots and stems), air quality maintenance,, water quality maintenance
Describe TWO ecosystem services provided for humans by forests. Explain how clear-cutting would affect each ecosystem service you describe.
Forests give provisioning services through their wood used as fuel or other human activities- If clear-cutting were to occur, the loss of these goods produced by the forests would cause a shortage of resources. Another ecosystem service forests provide us is as a regulating service as forests are a great sink of carbon from the atmosphere while they regulate and produce oxygen for human use. With clear-cutting, there would be a higher amount of CO2 in the atmosphere (a greenhouse gas) which would lead to higher temperatures and result in the lower amount of CO2 being converted into oxygen for humans to take in.
5.3 The Green Revolution
Shift in agriculture away from small, family operated farms to large, industrial-scale agribusiness
Increased use of mechanization, GMOs, irrigation, fertilizers, pesticides
Increased efficiency of lands, short-term profitability and food supply
Decreased world hunger and increased earth's carrying capacity
negative effects: soil erosion, biodiversity loss, ground or surface water contamination
Mechanization
Increased use of tractors for plowing and filling fields and combines for harvesting=increased yield + profit
Increased reliance on fossil fuels>emits GHG to atmosphere
Heavy machinery also compacts soil, decreasing H2O holding capacity>makes topsoil prone to erosion
Economies of scale: average costs of production fall as output increases
Large upfront expenditure justified by profits from increased production
Small farms cannot expend the up-front cost
Monoculture
Easy to plant, maintain, harvest
Only certain types of pests associated with this one crop
DOWNSIDES: loss of habitat and biodiversity, loss of ancestral varieties, increased pros of catastrophic event
Energy subsidy
Energy input per calorie of food produced
In US: 10 calorie energy input for every 1 calorie you consume
Energy input per calorie of food obtained is greater for modern agriculture practices than for traditional agriculture
Fossil fuel energy is primary energy subsidy for large-scale modern food production (to produce fertilizers/pesticides, to operate tractors, pump water for irrigation, harvest food and prepare for transport)
High-Yield Variety Crops
hybrid/ 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 ( india, pakistan, MX)
GMOs: crops with new genes spliced into their genome
BT bacteria’s pesticide producing material is given to other crops
GMOs
Genetically modified crops have genes for drought tolerance, pest resistance, faster growth, and larger fruit/grain
Increases profitability with few plants lost to drought, disease, or pests + larger plant size + yield/acre
All genetically identical so genetic diversity is decreased and susceptibility to diseases/pests is increased
Synthetic Fertilizer
Shift from organic fertilizers (manure/compost)>synthetic fertilizers (man made ammonium, nitrate, phosphate)
Increases yield/profit w more nutrients needed (N, P, K)
Excess nitrate, phosphate are washed fff fields into nearby waterway>eutrophication/algae blooms
Require ffs for production, releasing CO2
Irrigation
Drawing water from ground or nearby surface water + distributing it on fields = increase plant growth
Makes agriculture more possible in places that are too dry
Can deplete groundwater esp aquifers
Overwatering can drown roots, no O2 access, and cause soil salinization (increase salt level in soils)
Pesticides
Increase in use of synthetic pesticides: chemicals sprayed on crops that kills weeds, insects, rodents, etc that eat or damage crops
Increase yield and profit w few plants lost due to pests
Can wash off crops in runoff and kill or harm non-target species in local soils/waters
Ex. DDT thinned shells of bird eggs, esp eagles
Describe 1 environmental advantage and 1 environmental disadvantage of using GM crops
1 environmental advantage of using GM crops is higher yields per acre and less acreage needed which is a less loss of habitat, biodiversity. 1 environmental disadvantage of using GM crops is that GM crops w insect resistance may impact beneficial insects used for pollination, altered genes may impact human health w altered proteins and toxins
Describe 1 economic advantage and 1 economic disadvantage of using GM crops
1 economic advantage of using GM crops is the increased yield meaning there is an increased profit especially in places that could not grow crops before, reduced water loss that lowers associated costs. 1 economic disadvantage of using GM crops is that higher yields often lead to greater soil depletion, requiring higher costs of mitigation, decreased profit due to use of GM crops that gave increased fertilizer demand to reach yield potential
5.4 Impacts of Agricultural Practices
Arable land- capable of producing crops
Tilling:
Bare soil>soil erosion, evaporation
Eutrophication, need for fertilizer
Turned soil> impacts soil structure
Turned soil>sequestered carbon released as CO2
Eutrophication: overgrowth of algae
Mechanized farming equipment>impact soil, emissions, fossil fuels (habitat loss, water usage to get ff)
Slash and Burn Agriculture
Developing countries
Typically tropical rainforests (low-nutrient soil)
Subsistence (himself and family) farmers
Ash used as fertilizer
UNSUSTAINABLE
Nutrients provided by ash quickly used
Cut down new plot of land 4 crops
IMPACTS: desertification (forests cannot grow back), soil erosion, decreased albedo, increased evaporation, decreased water infiltration
Synthetic vs Organic fertilizers
N, P, K
Organic is from animal waste
Synthetic fertilizers PROS:
Easy to transport/use, timed released, customizable
Synthetic fertilizers CONS:
Water-soluble (runoff), often overused, does nothing to improve soil structure
Organic fertilizer CONS:
Must be gathered, nutrient levels unknown, harder to use
Organic fertilizer PROS:
Can be worked into soil (stays), contains partially digested vegetation>improves soil structure
5.5 Irrigation Methods
furrow irrigation: trench dug along crops and filled with water
Easy, inexpensive and water seeps into soil slowly
66% efficient, 33 lost to runoff and evap
Difficult to apply small amounts
Flood irrigation: flood entire filled, easier but more disruptive to plants
PROS: Easy, inexpensive, mechanization not required
CONS: Requires water nearby, not for all plant types
Can waterlogged soil/drown plants
80% efficient, 20 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 and conserves water
Very expensive, requires mechanization, placements makes any other processes difficult
Most efficient irrigation technique for dry/semiarid climates since less water is lost to evaporation
Used in dry/semiarid climates because water resources are limited and drip uses less water than other methods to reduce water use-l
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 and movement of sprinklers). Mpzz;es can clog ( less sediment in water), machinery run with electricity/FF
Waterlogging
Overwatering can saturate the soil, filling all soil pore space w water
nallow water into pores, so roots cant take in o2 they need
Can stunt growth/kill crops
Solution: Drip irrigation. Soil aeration- poking holes or cores in soil to allow air in and water to drain through soil
Soil Salinization
Salinization process of salt building up in soil over time
Groundwater used for irrigation naturally has small amount of salt
Water evap, salt left behind in soil>dehydrating plant roots and preventing growth
Solution: drip irrigation, soil aeration, flushing w fresh water, switching to freshwater source
Global Human Water Use
Industrial: power plants, metal/plastic manufacturing
Municipal: households ( toilets, shower, drinking water)
Agriculture: water for livestock irrigation water for crops
Aquifers & Groundwater
Groundwater: H2O is stored in pore space of permeable rock and sediment layers
Aquifers: usable groundwater deposits for humans
Replenished by groundwater recharge (rain water percolating down through soil into aquifer)
Unconfined aquifers recharge quickly
Confined aquifer recharge are longer-term water deposits that recharge more slowly
Ogallala aquifer: farmers drawing water from aquifer>water levels losing more than it is being replenished
Depletion of Aquifers
Cone depression: forms when water table is lowered by excessive pumping, depleting water and drying nearby wells
Saltwater intrusion: excessive pumping near coast lowers water table pressure>allowing saltwater to seep deeper into groundwater
FRQ about soil salinization:
Soil salinization occurs when groundwater is used for irrigation and as the water evaporates, salt is left behind in the soil which can become toxic for the plants. A solution to prevent or remediate soil salinization is to switch to a freshwater source in order to flush out the salt and keep using the less salty alternative. But one disadvantage of this solution is that it is very expensive and is not economically profitable to be spending so much on a freshwater resource.
5.6 Pest Control Methods
Pesticide Use and Overuse:
Pesticide treadmill: continuous use of pesticides that increase/stronger concentration and have unintended effects on the environment
Problems
Increasing use> runoff (kills organisms in water, contaminated drinking water); carried by wind to other areas, entry through wells
Killing of bees needed for pollination, biomagnification (storing of persistent of lower trophic level effect on apex predator)
Use
Reduce impacts of pests> maximizing yield of crops, increasing profit not affected by mold, insects etc.
Chemical Control with: pesticides, herbicides, fungicides, rodenticides, insecticides
5.7 Meat Production Methods
Meat overconsumption
When countries are developing they eat more meat
Land Use
Takes a lot of land (25% land on earth)
Animal waste and Emissions
Lots of animals raised for meat>lots of animal waste
Cows emit methane> GHG
Animal Waste
Increase turbidity>>Decrease in aquatic primary productivity, decrease in albedo
Increase in water temperature>>decrease in dissolved oxygen (DO) levels
Increase in organic matter/nutrient load>>increase in decomp by aerobic bacteria, decrease in DO levels, eutrophication
Soil Compaction, soil erosion
Reducing Meat Consumption
Reduce CO2, methane, N2O emissions, conserve water, reduce use of antibiotics and growth hormone, improve topsoil
CAFOs (concentrated animal feeding operation)
CAFOs can raise cattle, chickens, turkeys, pigs, sheep, goats, or any other livestock for consumption by humans
Large but efficient (to serve demand for meat)
Keeps meat production costs down= more affordable meat for consumers
BUT can lead to density-dependnet pathogenic infections; increased nmethane production, and acid-resistant E. coli
Crowded, create a lot of waste^^^ (animal waste section)
Free range grazing
Allows animals to graze on grass during their entire lifecycle
Allows animals to eat grass, the food they are designed to eat
Means less antibiotic use and less antibiotic residue in the meat
Uses animal waste as a natural fertilizer for the forage
Free range grazing and land use>more land area, non native organisms interfering, costs more, not using growth hormone
Requires large areas of land
May lead to overgrazing and land degradation
Leads to higher meat prices for consumer
Overgrazing
5.8 Impacts of Overfishing
Overfishing has led to extreme scarcity of some fish species, which lessens biodiversity in aquatic systems and harm people who depend on fishing for food and commerce
Longline: long line with evenly lined hooks held by flotation devices dragged behind ships (28 mi long)
Pro: efficient (lots of fish w 1 pass),
Con: overfishing if unregulated, non-target species than intended will eat and get hooked
Drift net/gill net: long net set at varying depths pulled by ships/boats (caught by gills)
Pros: efficient
Cons: can lead to overfishing, can catch unintended organisms
Purse seine: massive net that has 2 drawstrings, catch entire school of fish, draw bottom and top shut to draw up fish
Pros: efficient
Cons: can lead to overfishing, can catch unintended organisms
Trawling: net shaped like cone that is dragged through water
Pros: efficient
Cons: can lead to overfishing, can catch unintended organisms, erased DESTROYS HABITAT AS ITS DRAGGED ALONG BOTTOM
Sonar: locating school of fish, seafloor
Pros: more money, fish
Cons: interferes w navigational systems of aquatic mammals like whales
Bycatch: non target species
Processed w rest of everything, tossed back out
Making fishing more sustainable
Catch limits based on MSY (maximum sustainable yield)
Limit age/size of fish caught
Modify techniques to reduce bycatch
laws/treaties that protect critical species: US Endangered Species Act; Convention on International Trade in Endangered Species of Wild Flora and Fauna
Modified fishing techniques: TED is a turtle exclusion device on trawling nets
FRQ: describe commercial practices and explain the role it plays in the depletion of marine organisms
Bottom trawling is when you drag a net or line with hooks along the bottom of the ocean that destroys the benthic habitat and catches many non target species
Sonar uses sound waves to locate fish or see the bottom that allows ships to locate larger school of fish quickly and target them as well as throw off animals using their navigational systems like whales to wash up on the shore
Identify 1 international regulation or US federal law that applied to the harvesting of marine food resources and explain how it helps to manage marine species
Endangered Species Act-
The convention on international trade in endangered species of wild flora and fauna
Identify and explain a way other than passing a law or signing an international treaty, to reduce overfishing of a fish species
Set a catch limit for each commercial fishing company in a country, setting a MSY for an entire country would ensure there will be enough fish to reproduce and replenish fish stocks
Offer incentive to commercial fishing companies and countries that fish sustainable, incentivizing can motivate corporations and countries to shift towards using more sustainable fishing methods
5.10 Impacts of Urbanization
Urban sprawl: change in pop distribution from high pop density areas>low density suburbs that spread into rural lands
Urbanization: shift from lifestyle on agricultural, rural>non agricultural jobs that has high pop density
Pro: mass transit (reduced FF emission), activity level up, more efficient use of space, less land impact
Urban Blighet/Urban Decay: decline in urban neighborhoods due to taxpayers moving out>leads to loss of tax dollars that reduce city services, an increase in abandoned buildings and increase in crime
Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle
Urbanization through the burning of fossil fuels and landfills affects the carbon cycle by increasing the amount of CO2 in the atmosphere
Impermeable surfaces>can’t recharge water/groundwater, runoff
Heat island effect; more veg=cooler temp; less veg=higher temp
FRQ: describe 2 causes of urban sprawl
Transportation: increased use/reliance on automobiles, improved roads, lower gas prices promote driving,
Quality of life: desire for property/yard/lower density, better quality suburban schools
Discuss 2 human health effects associated with urban sprawl;
Increased air pollution: asthma, bronchitis
Less exercise due to auto travel time/commuter diet: obesity, diabetes
Increased driving: personal injuries due to automobile use/crashes
Describe 2 steps a municipality could take to encourage emart growth in order to limit urban sprawl
Transportation: subsidize mass transit to encourage less automobile use
Tax incentives/reduced taxes for living in city
5.11 Ecological Footprints
Ecological footprint: a measure of how many resources a person uses, expressed in an area of land
5 variables: carbon footprint>energy; built-up land>settlements; forests>timber and paper; cropland and pasture>food and fibers; fisheries>seafood
Less developed/developing countries have lower ecological footprint than developed countries
Factors to consider in calculation of ecological footprint: cropland, grazing lands, fishing grounds, forested areas, built-up (urbanized) lands, carbon demand
5.12 Introduction to Sustainability
Sustainability refers to humans living on Earth and their use of resources without depletion of the resources for future generations
Indicators: biological diversity, food production, average global surface temp, CO2 concentrations, human pop, and resource depletion rates
Biological diversity> healthier ecosystems are resistant to disturbances
Food production> poor practices lead to soil degradation and water pollution
Global surface temp and CO2 concentrations>excessive CO2 increases global temp creating climate change
Human pop> exponential growth stresses the planet
Resource depletion> will this resource be available in the future
Sustainable Yield: The amount of a renewable resource that can be taken without reducing the available supply (50% of carrying capacity)
5.13 Methods to Reduce Urban Runoff
Consequences of urban runoff
Decreased infiltration (groundwater recharge) from impervious surfaces
Rain washes pollutants into storm drains and & local surface waters
Pollutants & effects:
Salt (plant/insect death)
Sediment (turbidity)
Fertilizer (eutrophication)
Pesticides
Oil & gas (suffocate fish/kill aq insects)
Solution: Permeable Pavement
Specifically designed to allow stormwater to infiltrate & exchange ground water
Decreases runoff, decreasing pollutants carried into storm drains & into local surface water
Decreases likelihood of flossing during heavy rainfall
More costly
Solution: rain garden
Garden planted in urban areas, especially surrounding a storm drain
Decreases runoff by allowing it to soak into garden soil surrounding storm drain
Creates hab for pollinators
Solution: public transit
More cars on road= more pollutants on streets to runoff into storm drains and local waters
More cars=more lands and parking lot (impervious surfaces) and more stormwater runoff
Public transit decreases urban runoff, pollutants on road, CO2 emissions and
Solution: Building Up, not Out
Building vertically decreases impervious surfaces (decreasing urban runoff)
Can be combined with green roof or rooftop garden to further decrease runoff
Sequesters co2 and filters air pollutants
Plants absorb
5.14 Integrated Pest Management (IPM)
A combination of methods used to effectively control pest species while minimizing the disruption of the environment
Goal is to reduce the amount of chemical pesticides used to reduce the pesticide treadmill and poisoning of non-target species and humans
Biological controls: introduction of natural pest predators
Physical controls: barriers that protect crops
Chemical controls: poisons that kill pest species
Crop Rotation: switching crops in harvests
Intercropping: cultivation of 2+ crops grown at same time (2 pests w common predator)
By switch crops, pest species many not accumulate that warrant pesticide use
THE USE OF CHEMICAL PESTICIDES CAN CAUSE HARM 2 ENVIRONMENT (kills non-targets wildlife, contaminates water supplies, affects human health)
IPM PROS:
Decreases amount of chemical pesticides sprayed on crops, economic savings, sustainable, targeted, minimizes loss of pollinators, minimize health risk, decreases pesticide resistance
IPM DRAWBACKS:
Complex, slow, expensive
The use of IPM reduces the risk that pesticides pose to wildlife, water supplies, and human health
IPM mimizies disruptions to the environment and threats to human health BUT is complex and expensive
5.15 Sustainable Agriculture
Preservation of soil is essential to maintaining sustainable food production practices
Contour Plowing: Preserved natural topography of the land and leaves oil intact (less soil erosion)
Windbreaks (adding trees): Reduces wind erosion that may blow soil away
Strip cropping: Harvesting one crop at a different time will leave one crop holding the soil in place
Terracing: hill or mountain; decreases the velocity of water going downhill>>reducing soil erosion
No till agriculture: leave soil in place and does not loosen it so it can resist erosion
Perennial crops: crop roots hold soil together year-round, does not have to be replanted
Practices that improve soil fertility include:
Crop rotation: may replenish soils of nutrients naturally (ex. Legumes add nitrogen to the soil)
Green manure: adds bulk and Nitrogen, Phosphorus, Potassium to soil that slowly decomposes
Limestone: addition of limestone adds valuable calcium to soil and increases pH making soils more alkaline
Overgrazing is unsustainable in food production
Overgrazing: extensive grazing that causes damage to plants (leads to soil erosion and destruction of pasturable fields)
Rotational Grazing: the cycling of livestock around a particular part of their pasture to not overgraze 1 area (allows the cover crop to replenish and hold soil in place)
FRQ: describe 1 agricultural practice that can lead to the degradation of agricultural land
plowing/tilling the soil increases soil erosion (by breaking up the soil structure) and reduces fertility
Using monocultures or the growing of 1 crops over and over again will deplete the soil of the needed nutrients
Overgrazing by livestock leads to a loss of soil cover and increases soil erosion without the top cover to hold it in place
Describe a potential solution or technique that can prevent or reduce degradation of agricultural land
Contour plowing uses the contours of the land to minimize soil erosion
Terracing, growing crops on side of hills or mountains in a series of steps reduces soil erosion
Perennial crops remain in the soil year-round and can survive for several years which reduces the need for replanting and improving or disturbing the structure of the soil which limits soil erosion
5.16 Aquaculture
Aquaculture: the farming of fish, shellfish, mollusks, crustaceans or aquatic plants by an individual or corporation with the intent to sell the farmned organisms to consumers for profit
Can occur in both marine and freshwater environments, depending on organism farmers
China is leader in aquaculture production in marine and freshwater environments
Aquaculture has expanded b/c it is highly efficient, requires only small areas of water, requires little fossil fuel inputs
AQUACULTURES HELPS REDUCE OVERFISHING AND PROVIDES AFFORDABLE, HIGH-QUALITY PROTEIN TO HUMANS EFFECIENTLY AND W LESS FOSSIL FUEL INPUTS
CONS: can waste from organisms/uneaten food pellets can contaminate waterways and fish that escape may compete or breed w wild fish
Density of fish in aquacultures can lead to disease incidence which can be transmitted to wild fish
Aquaculture as an environmental solution:
Advantages: provides high-quality protein to growing human pop; provides stable income to fisherfolk w less risk than open-water; less acreage and less water; fewer fossil fuel input needed than terrestrial agriculture
Disadvantages: nitrogenous waste can pollute waterways>>eutrophication; Uneaten feed can pollute waterways>water-quality issues; escaped farmed organisms can interbreed or compete w wild organisms; diseases/parasites from densely packed farned pop can spread to wild; medication to control disease in farmed can pollute waterways
FRQ: describe an advantage of aquaculture that helps minimize natural resource use
Less water, less fossil fuel inputs (minimizes natural resource use)
Identify a disadvantage of aquaculture and describe how that disadvantage might lead to an unintended environmental consequence
Escape of farmed organisms can lead to competition and change to the wild organisms due to competition and interbreeding (foodweb change, diversity)
5.17 Sustainable Forestry
Forest ecosystem services: food, medicine, fuel, fiber, timer, carbon sequestration, air purification, water purification, flood and erosion control, maintenance of biodiversity, recreation, aesthetic and cultural value
Sustainable forestry: refers to a collection of methods that attempt to reduce the human impact of harvesting trees and using forest resources
Methods for mitigating deforestation
Reforestation: intentional restocking of existing forests/woodlands that have been depleted
Using and buying wood harvested by ecologically sustainable forestry techniques:
Selective harvesting of trees, prohibiting logging in ecologically sensitive or highly biodiverse areas of forested land, transportation of felled trees via techniques that lessen ecological disruption and soil compaction
Reusing/repurposing/recycling wood
Methods to protect forests from pathogens and insects include:
Integrated Pest management (IPM): continual monitoring of health of tree stands, thinning of underbush, knowledge of common pest species, understanding economic pest threshold, setting pest traps/manual weeding, biological control w natural predators, chemical control w repellents/pesticides/herbicides (last resort)
Removal of affected trees: helps slow spread of infestations in a stand
Prescribed burn: method by which forests are set on fire under controlled conditions to reduce the occurrence of natural fires
Fire removes excess understory plants, dead tree limbs, needles, branches
Selective removal can reduce severity of natural forest fires by reducing the amount of dry matter available as fuel/help reduce pest infestations
Sustainable forestry methods
Increase the economic costs of using forest resources and reduce profit margins for timber companies
Require forestry workers to be trained on how to properly use these techniques
PRO of mitigation of deforestation: preserves biodiversity, preserved critical ecosystems services that forests provide, economically supports organizations and timber companies that employ sustainable methods, reusing wood reduced need to cut new timber
PRO of using IPM/selective tree removal for pest management: ensures forestry workers are closely monitoring tree stands; reduces impact of pesticide/herbicide use on non-target species, soil, water; reduces likelihood of trophic structure disruption from pest eradication; more closely mimics natural balance of ecosystem
PRO of prescribed burns: lessen the severity of naturally-occurring fires by removing underbrush and debris; encourage new growth of nntaive species; help manage pest species
FRQ: provide 1 reason why fire-suppression policies lead to increased beetle activity
Fire-suppression means that the undergrowth is not burned where pests usually breed
When the pest accumulate in the undergrowth, it affects the mature trees more>and in a forest that is not allowed to burn, there are more mature trees
Explain how prescribed burns might mitigate the impact of mountain pine beetles on forests
Prescribed burns would burn the understory in a forest that would reduce pest populations
Help clear understory so that smaller saplings can come up which will make a mix of tree growth and not a majority of large trees that are preferred by the beetles
A national forest service intern recommends using a combination of IPM methods and selective tree removal to reduce beetle pop>>>
Explain 2 advantages of this approach that would justify its use by the forest service for beetle control
It reduces the effect of chemical pesticides on nontarget species
Selective tree removal means keeping the biodiversity of the forest intact b/c only diseased trees are removed
1 MBTU= 1,000,000 BTU
6.1 Renewable vs Nonrenewable Energy Sources
Nonrenewable energy sources are in a fixed amount and involve energy transformation that cannot be easily replaced
Fossil fuels: fossilized remains of ancient biomass that take millions of years to form
Coal, oil, natural gas
Nuclear: energy generated from uranium or other radioactive fuels
Renewable energy sources are those that can be replenished naturally, at or near the rate of consumption, and rescued
Depletable renewables can run out if overused (biomass)
Nondepletable renewables do not run out if overused (solar, wind hydroelectric, )
Fossil fuels
Derived from biological material that fossilized millions of years ago
Form in anaerobic conditions (swamps)
oil/gas trapped in rocks
Renewable Energy
Rate of consumption:
Rate of use must be at or below rate of regeneration for renewables
Fossil fuels will run out because they take far longer to regenerate than the rate we use them
FRQ: explain whether or not biomass is a renewable energy source + justify
Biomass is a renewable energy source because it can be replenished naturally at a rate near consumption but can be depletable and run out if overused
Non-renewable energy resources – Resources that have a finite amount available on Earth for human use.
Non-depletable resources – Resources that cannot be used up on a human time scale.
Potentially renewable resources – A resource that can be sustained on Earth as long as consumption does not outpace growth/replenishment.
Renewable resources – Broad category for non-depletable and potentially renewable resources.
Potential energy is stored energy and includes chemical, nuclear, gravitational, or mechanical energy.
Kinetic energy is energy created from movement and includes radiant energy, thermal energy, sound, motion and electrical energy.