Exam 2 Lecture Slide Content Flashcards
HYPOTHESIS, TESTING, & THE SCIENTIFIC PROCESS
What is a theory?
A theory is a broad, yet concise explanation for a wide range of phenomena. Often the generalized product of many hypotheses. Ex.) plate tectonics, natural selection
What are some characteristics of a theory?
-Reinforced and updated by a wide range of experiments and observational studies
-Predictive
What is a hypothesis?
A proposed explanation for a relatively narrow set of phenomena (ex.) addition of amendments to soil will have a significant and positive effect of plants ability to uptake lead)
What is a characteristic of hypothesis?
-Based on background info and/or initial observations
-Specific
-Testable
-Focused
What is the difference between the null and alternative hypothesis?
Null- there is no relation between variables
Alternative- there is a significant relation between variables
In regards to scientific testing, what is the difference between evidence and an argument?
-Expectation + Observation = Evidence; Evidence lends support to help refute without “confirming” with certainty
-Background Information+Expectation+Observation= Argument; Arguments can lead to the support, rejection, revision, or replacement of a Hypothesis
In regards to scientific testing, what is the importance of control?
Controlling variables is paramount in minimizing potential for error or interference between variables
In regards to scientific testing, what is the importance of assumptions?
Assumptions are fundamental in conducting experiments as they allow us to believe in the certainty of specific actions taking place
What are some ways that ideas and hypothesis are shared within the scientific community?
Peer review, replication and discussion, eliminating bias, feedback for publication
SOILS
What the five factors of soil formation?
Organisms, Topography, Time, Climate, Parent Material
What are the Soil Horizons in order?
-O Horizon (Loose and partly decaying organic material)
-A Horizon (Mineral matter mixed with some humus)
-E Horizon (Eluviation layer; zone of leeching)
-B Horizon (Accumulation of minerals transported from above)
-C Horizon (Partially altered parent material)
-R Horizon (Unweathered parent material Bedrock)
What are the three classes of soil?
Sand, Silt, Clay
How does particle size vary between the three soil classes? How do these particle sizes effect water retention in each class?
-Sand has the largest and grittiest particles
-Silt has the medium-sized smooth particles
-Clay has the smallest and stickiest particles
-Too much sand means that there is no small pores and no water retention, but too. much clay means that there is no large pores and no water drainage; happy medium is best for water retention!
In regards to water retention, what is the difference in gravitational water, capillary water, and hygroscopic water?
-Gravitational water: water that drains right through the soil
-Capillary water: water remaining in the soil that is readily available for plants
-Hygroscopic water: Remaining water that is held too tightly for plants to draw
What are the four pools of plant nutrients?
-Soil minerals (naturally occurring inorganic solids, major source of soil-supplied nutrients, longest term storage)
-Organic matter (contains carbon, storage of N and anions)
-Adsborbed nutrients (ions attracted to soil colloids, readily available to plants)
-Dissolved ions (ions in solution, the most readily available to plants)
What is cation exchange capacity?
-Cation Exchange Capacity: Gives an insight into the nutrient retention capacity of soil and the total capacity of soil to hold exchangeable cations; CEC is an important index of nutrient status because available cations are the most important source of immediately available plant nutrients
What are some functions of urban soil?
-Regulation of water flow and quality
-Carbon storage
-Reservoir for biodiversity
-Platform for buildings
-Support for food and biomass production
What are two examples of soil contaminants and their characteristics?
-Lead (Pb): Neurotoxin affecting cognitive development and is immobile (lead-based paint, gasoline emissions)
-Arsenic (As): Human carcinogen that is very slowly leeching through soils (pesticides, pressure treated lumber)
BIODIVERSITY
What is speciation?
Speciation: Process by which evolution generates new species. Speciation rates depend on number of current species and the development of new species from existing species.
What is allopatric vs. sympatric speciation?
-Allopatric speciation: When the population becomes geographically isolated from the parent population (ex.) when a river cuts between two tree populations)
-Sympatric speciation: When two groups live in the same area but become different species (ex.) mutation)
What is Extinction?
Extinction: When species fail to reproduce and no individuals remain
What is the difference between background vs. mass extinction?
-Background extinction: slow on-going rate of extinction
-Mass extinction: when extinction rate is much greater than background rate
What is Biodiversity?
Biodiversity: Number and variety of living organisms
How do we define biodiversity on an ecosystem level, species level, and genetic level?
-Ecosystem Level- Ecosystem diversity: variety in number of biomes and variation within ecosystems for types of organisms, habitats and processes
-Species Level- Species richness (number of species in an area)/species evenness (species distribution)
-Genetic Level- Genetic diversity: information in DNA and raw material for natural selection
What is Functional Biodiversity?
Functional Biodiversity: The value and range of species and their traits that impact ecosystem function; general consensus that there are more species near the equator and in oceans
When relating to species distribution, what is an endemic species? What is dispersal?
-Endemic Species: A species that is restricted to a particular geographic region and thought to have originated from there
-Dispersal: movement of individuals from their birth site to their breeding site (ex.) salmon)
What does the species-area relationship say?
Number of species in an area increases with the area size
What does the species-energy relationship say?
-In terrestrial biomes, net primary production peaks near the equator and declines with latitude
-In marine environments, the coastal areas follow terrestrial patterns but in deeper waters, biodiversity peaks at mid-latitudes
What is the difference in keystone and passenger species?
-Keystone species: controls the integrity of a community or ecosystem
-Passenger species: have a relatively small effect on ecosystems
What are three ways that humans utilize species diversity?
-Diffusing chemical coevolution: natural selection favors individuals that accumulate compounds effective against a wide variety of enemies
-Extremophiles: organisms that live in extreme environments
-Ethnobotany: how different groups of people use plants
What are some threats to biodiversity both human and nonhuman?
-Alien species: a new species to an ecosystem
-Invasive species: displace and threaten indigenous species
-IPAT equation: increased affluence and population reduce biodiversity
-Habitat conversion: changes in land use/cover
-Habitat fragmentation: break-up of continuous habitat
What is the Enemy Release Hypothesis?
-An alien species population grows rapidly if the number of pathogens in native range exceeds ones in naturalized range
What is Nutrient Loading?
idk
How has hunting and harvesting affected biodiversity?
-Creates empty ecosystems
-Human hunting creates a new form of natural selection
-Predator control reduces species that compete with humans for crops or game
How does climate change impact biodiversity?
-Since species have adapted to live within certain temperature ranges, warming temperatures can disrupt biodiversity patterns
What are the four factors to preserving biodiversity?
-Uniqueness: Unique genetic composition and knowledge
-Usefulness: commercial or cultural value
-Probability of extinction: how much effort is necessary
-Cost: economic cost of saving the species
What is the difference betwen In-situ v. Ex-situ conservation?
-In-situ: Preserves species in natural habitat
-Ex-situ: Preserves genetic material
CLIMATE CHANGE
What is the difference between weather and climate?
-Weather: temperature, precipitation, wind speed, cloud cover, etc. at a particular time and place
-Climate: patterns of weather conditions across an annual cycle
What is Radiative Balance? How does radiative balance affect temperature?
Radiative Balance is composed of long wave and short wave radiation that indicates the amount of energy available on Earth’s surface. Earth will heat up until the energy that it radiates away equals the amount of energy that it absorbs from the sun.
Equation: SW(in) + LW(in)= SW(out) + LW(out)
What is the Greenhouse Effect and how does it affect global temperature?
-Greenhouse Effect: Process through which heat is trapped near Earth’s surface in substances known as GHG
-If there was no atmosphere on Earth, the temperature would be far too cold to sustain human life. Because the atmosphere absorbs some of the heat and radiates it back down to Earth through the Effect, the planet is habitable.
What are Greenhouse Gases?
Greenhouse Gases: Gases in the atmosphere that raise the surface temperature of Earth.
What is the role of GHG in warming the planet?
GHG absorb outgoing Longwave radiation and re-emit in all directions warming the planet.
What is the Radiative Equilibrium?
Radiative Equilibrium: Energy In= Energy Out; Pertains to the idea that the Earth cannot keep absorbing energy indefinitely.
What is Radiative Forcing?
Radiative Forcing: An index of measuring the potency of GHG from the amount and frequency of infrared radiation that it can absorb. GHG potency is measured as the radiative forcing per molecule.
What are some ways that humans have altered GHG emissions?
-Humans have altered GHG emissions through agriculture- both in deforestation and agricultural management
What are aerosols and what is their role in global climate?
Aerosols are particles suspended in the air that are smaller than droplets; aerosols reflect sunlight and lead to cooling
What are some consequences of a shifting baseline climate?
-More frequent climate extremes (ex.) increased intensity of heatwaves in Australia)
-Sea-level rise
What are three factors that contribute to sea-level rise?
-Melting ice sheets
-Increased average global temperature
-Thermal expansion (as the ocean warms in response to climate change, seawater expands leading to sea level rise)
GROFFMAN LECTURE: SNOW IS GOOD WORMS ARE BAD
What are the four types of ecosystem services?
-Supporting (nutrient cycling, soil formation, primary production)
-Provisioning (food, water, wood, other resources)
-Regulating (climate regulation, disease regulation, water regulation)
-Cultural (aestethic, spiritual, etc.)
What are the five constituents of well-being?
-Security (personal safety, secure resource access)
-Basic material for a good life (shelter, access to goods)
-Health (strength, feeling well)
-Good social relations (social cohesion, mutual respect)
-Freedom of choice and action
What are state vs. stochastic factors?
-State factors are factors that give a general framework for an ecosystem (climate, time, topography, biota)
-Stochastic factors are factors that push an ecosystem away from its expected state (ex.) extreme climate events, geologic events, anthropogenic climate change)
According to Groffman, why is snow good?
-Snow is an insulator on the forest floor
-Lack of snow results in soil freezing, root and microbial mortality, and accelerated nutrient loss
What were the results of Groffman’s study on snow?
-Minor freezing events affected roots, microbes and solute
-Freeze effects are mediated by physical disruption of root/microbial interactions
-Elevation gradient studies show similar results as plot manipulation studies
-Winter climate change has mutliple components and effects
According to Groffman, why are worms bad?
-The vast majority of earthworm species are exotic and invasive
-Invasion of these species caused “cascading” effects on soil
What were the results of Groffmans study?
-Earthworms fundamentally alter ecosystem structure, function, and services in temperate forests
FORESTS
What services do cut down forests provide?
-Materials (buildings, furniture, paper)
-Energy (cooking, heating, electricity generation)
What services do standing forests provide?
-Climate regulation (store enough carbon to double the concentration of CO2 in the atmosphere)
-Soil conservation (tree roots protect soil from eroding)
-Biodiversity (most terrestrial animal species are forest species)
How do trees affect temperature?
-Trees affect temperature through transpiration, which helps them cool local climates
How do trees help with moisture cycling?
Trees contribute to the water cycle through evapotranspiration which helps regulate precipitation.
How do we measure net deforestation?
Net deforestation can be measured by the following equation:
Tree cover loss- Tree cover gain
What are primary forests?
Primary forests: Late successional native forests containing the most carbon and biodiversity
What are secondary forests?
Secondary forests: still-regrowing early successional forests of mostly native species that have les biodiversity and total c stock than primary forests but faster c sequestration rates
What are plantations?
Forests of one intentionally-planted species with the least biodiversity, but still can provide other ecosystem services
When does a forest get cut and how are these values measured?
Forests get cut when the value of cutting timber or using the land for other purposes is greater than the value of leaving it standing. These values are expressed as RENTS.
Rents from doing A= (revenues of doing A)-(cost of doing A)
What are institutions in relation to forest conservation policies and what are some examples of important institutions for deforestation?
Institutions are the sets of formal and informal rules and norms that shape interactions among people and organizations (i.e. markets and exchanges)- important institutions for deforestation relate to land rights and land exchange.
What are timber concessions?
Timber concessions: Temporary rights given to companies to log an area of land for a limited amount of time; granted for 20-30 years- about the time it takes to grow one stand of trees
What is currently threatening the Brazilian Amazon Forests?
Agricultural development- new roads and infrastructure bring new settlement from the southeastern “arc of deforestation” into the interior. Smallholder ranchers are responsible for the land clearing- these ranchers are prone to sell land to richer people and companies for mechanized agriculture
What are some market-based policies for forest protection? What are the benefits and drawbacks of these policies?
idk
What are some command and control policies for forest protection?
Some examples of command and control are mandating selective logging in oppose to clear cutting or protecting areas. These practices help, but are costly to enforce and can introduce their own issues
WATER
What percentage of Earth is saltwater? What percentage is freshwater?
97.5% of Earth is saltwater with only 2.5% being freshwater- of this, 79% is stored in ice caps/glaciers, 20% in groundwater, and 1% in other freshwater sources
What are the important steps in the hydrological cycle?
Evaporation-> Condensation-> Precipitation-> Infiltration/Runoff
How can we find the residence time of water in a steady-state system?
Remember that residence time in steady-state systems is defined by the inflow= the outflow.
From this, we can use the equation T(r)=Volume/Flux
Study the example in the lecture slides
What is the definition of evaporation?
Evaporation: Change in state from liquid to gas
What is the definition of condensation?
Condensation: The conversion of a vapor or gas to a liquid
What is the definition of precipitation?
Precipitation: Rain, snow, or sleet that falls to the ground
What is the definition of infiltration?
Infiltration: Permeation of a liquid into something by filtration (in the water cycle, this means precipitation being absorbed by the soil)
What is an aquifer?
Aquifer: When infiltrating water hits an impermeable layer causing water to accumulate filling all the pores underground.
What is the water table?
The top of the saturated aquifer
What is the recharge area?
Land area whose groundwater flows to the aquifer
What is groundwater?
Groundwater: Water that exists underground in saturated zones beneath the land surface filling the pores and fractures in sediment or rock
What is runoff?
Runoff: Water that does not infiltrate soil and moves over the surface; runoff follows the lay of the land
What are the two main categories of human water management?
-Water storage (dams and reservoirs) and water diversion (canals and aqueducts); both are types of infrastructure to help correct the mismatch in space and time
What are some pros and cons to dams?
Dams and other forms of water management are effective in correcting the mismatch between supply and demand for water over time as water is often available irregularly throughout the year and varies amongst global populations.
However, dams also have negative effects- they can flood communities, disrupt sediment transport, and disrupt migration of fish.
What is desalination?
Desalination: Makes saltwater available to humans by either boiling or pushing the saltwater. Desalination is costly.
In relations to groundwater, what is the difference between confined and unconfined aquifers?
idk
What is offstream water use?
Off-stream water use: water diverted or withdrawn from surface or groundwater
What are the two classifications of offstream water use?
-Withdrawal (water removed from its source); discharge is water returned
-Consumption (difference between the two)
Consumption= withdrawal-discharge
What are the four primary usages for water?
-Agriculture (irrigation)
-Industry (solvent, coolant, and transport agent)
-Municipal (basic needs, lawns, swimming pools, running of government)
-Energy (steam generation and cooling)
In regards to human water use, what is instream uses?
Instream uses: Involve the benefit from water without removing or diverting it (ex.) shipping, hydroelectric energy, recreation, etc.)
What are some consequences of mining groundwater?
-Liberates harmful contaminants and pumps them to surface (ex.) arsenic contamination near Dhaka, Bangladesh)
-Voids left behind can exacerbate saltwater intrusion
What is Biochemical Oxygen Demand (BOD)?
BOD: Amount of oxygen required for microorganisms to metabolize organic material in a water stream over some period
What are point vs non-point sources of contamination?
Point: Industrial contaminants tend to come from waste outlets
Non-point sources: agricultural contaminants wash from/through landscapes
What is the downstream conflict?
Concept that blocking/consuming/ polluting water upstream changes what is available downstream- can invite conflict among upstream and downstream users including irrigators, power providers, fishers, and recreational users
What is the purpose of water rights? What is the consequence of them?
Water rights are used to establish the allocation of water amongst users, but they are difficult to assign.
What are riparian water rights?
Riparian water rights: Assign a share of water flow to all parties whose land borders a surface water flow, but do not allow parties to divert the water flow
What is the Prior Appropriation Doctrine?
PAD: Doctrine that the earliest users of water have the highest priority rights and later users have their rights curtailed during shortage (ex.) California)
AGRICULTURE (this one is beefy)
What is agriculture?
Agriculture: Manipulation of natural ecosystems to increase the amount of edible energy sources they produce (changes in land use, manipulation of species)
What are the three key theories on what drove initial adoption of agriculture?
-Technical Change Hypothesis: Theory that agriculture emerges with increased human technical capacity- better knowledge and tools over time
-Coevolutionary Hypothesis: Theory that agriculture emerges in a positive feedback with human activity- initial clearing of trees creates more sunlit areas which creates more space for growth
-Resource Depletion Hypothesis: Theory that hunting gets more difficult over time due to the best-first principle; EROI of hunting is better suited for a small pop but agriculture EROI is better suited for a large pop
Seven steps required to maintaining agriculture
-Clearing land
-Planting seeds
-Fertilizing soil
-Irrigation
-Suppressing succession
-Pest control
-Harvesting
-Should be noted that agriculture process is essentially an ongoing ecosystem disturbance
What is the difference between intensive and extensive agriculture?
Intensive- high levels of input relative to the amount of land in use
Extensive- low levels of input relative to the amount of land in use
Inputs include labor, pesticides, capital, fertilizers, machines, etc.
What are some characteristics of extensive agriculture?
-Common in areas with low population density just on the threshold of hunting and gathering
-Slash and burn and/or nomadic herding
What are some characteristics of intensive agriculture?
-Common where good agricultural land is scarce and labor abundant
-As populations grow denser, richer, and more technological- there is a visible shift towards intensive production
What are some significant by-products of the Green Revolution?
-Access to cheap fertilizer
-Breeding of high-yielding cultivars
-Irrigation and pesticides
How have selection pressures (selective breeding) altered crop varieties?
-Shorter plants
-Thicker, stronger stalks
-More/larger grains
Expressed in grain mass: crop mass
How did the Green Revolution increase crop yields?
-Increases the maximum yield or “yield ceiling” or crops
-Allowed farmers to get closer to this maximum through new inputs (fertilizers, irrigation)
How did the Green Revolution impact food in relation to people?
The Green Revolution increases world food production by 3 while population increased by a factor of 2.3- this resulted in people being better nourished on average, cut food prices, and facilitated economies of sale (frees people to do other jobs)
What are some environmental impacts of the Green Revolution?
-Fossil fuel, water, and chemical footprints of agriculture grew strongly consequently resulting in greenhouse gas emissions, eutrophication, and pesticide resistance
