exam #2 Flashcards
(148 cards)
1
Q
what are the components of soil?
A
organic matter, air, water, mixed particles
2
Q
what are the 5 factors of soil formation?
A
5 factors: climate, topography, time, parent material, organisms
3
Q
how is soil formed?
A
the weathering and erosion of rocks breaks down parent material, both rocks and organic decaying material over time, or sediments left by glaciers; layers eventually form and new organic material accumulates, contributing nutrients and soil structure; its a product of the interaction between rocks, living organisms, climate, topography, and time
4
Q
what is humus?
A
decomposed organic matter that remains in soil for a long time; it helps structure and slowly releases nutrients
5
Q
sand particles
A
largest particles, lots of space between them –> less water retention
6
Q
clay particles
A
smallest particles, sticky, little space between particles –> high water retention
7
Q
gravitational water
A
water in soil from precipitation that moves into soil from gravity, not available for plant uptake
8
Q
capillary water
A
water that fills a soils micropores & held with moderate force
9
Q
hygroscopic water
A
tightly held water that forms a thin film around individual soil particles; too tight for plants to draw, allows for water storage through cohesion
10
Q
loam
A
mixture of clay, sand, silt
11
Q
what are the 6 soil horizons?
A
O - loose partially decayed organic matter (topsoil)
A - mineral matter mixed w/ humus
E - zone of leaching
B - accumulation of minerals transported from above
C - partially altered parent material
R - bedrock (unwethered plant material)
12
Q
4 pools of plant nutrients
for soil
A
soil minerals (major source of nutrients EXCEPT N)
organic matter
absorbed nutrients
dissolved ions
13
Q
what are urban soils like?
A
high heterogeneity (variation), temp affected from urban heat effect, limited resource
14
Q
what are some soil contaminants & their effects?
A
lead & arsenic from pesticides and paint, higher concentrations in inner cities, get absorbed through plant uptake and groundwater
15
Q
what are strategies to mitigate soil contamination?
A
add mulch/organic matter, lime to increase pH, use diff tilling practices, place gardens away from industrial areas
16
Q
what is the rate of soil erosion determined by?
A
rainfall, soil erodibility (ease at which water percolates through soil), slope length, land cover, erosion control particles, distribution of water among precipitation events/timing
17
Q
what are the social costs of poor soil practices?
A
eutrophication and siltation of streams
18
Q
what is the difference between soil and dirt?
A
soil is more complex than just dirt, as it involves water content, particle size, organisms, microorganisms; they are living systems and provide all nutrients for plant growth
19
Q
where do new species come from?
A
allopatric speciation - population becomes geographically isolated from parent population ex. galapagos finches
sympatric speciation - two groups live in the same area but evolve into different species ex. based on available niches (insects, apple maggot)
20
Q
what drives speciation?
A
random drift (genetic drift) random changes in gene pool & natural selection
21
Q
species richness vs species eveness
A
species richness refers to the amount of different species in an ecosystem (measure of biodiversity) while species evenness refers to the distribution of individuals among species
22
Q
why is it not enough to report only species richness when assessing biodiversity?
A
it does not consider the abundance or distribution of species, or the variety of ecological functions and roles that species play within an ecosystem, genetic diversity within individual species; species eveness can be an indicator of how stable an ecosystem is, having balance contributes to the overall health & balance of an ecosystem
23
Q
why are there more species near the equator?
A
climate stability + consistent sunlight = constant env to thrive in, higher rates of photosynthesis create greater levels of productivity –> more resources and energy able to be cycled, lack of extreme seasonal variations = easier to survive
24
Q
how are species distributed?
A
endemic species which are restricted to a particular region and thought to have originated from there, then dispersal = movement of individuals from their birth site to other breeding sites or from one breeding site to another
25
describe the species-area relationship
the # of species in an area increases with area size, leading to more diverse habitats, less issues with disturbances, larger populations supported, and more potential for allopatric speciation
26
describe the species-energy relationship
terrestrial biomes: NPP peaks near equator and declines with latitude
marine environments: in coastal areas, follow terrestrial pattern; for deeper waters, biodiversity peaks at midlatitudes
27
biocentric vs anthropocentric
biocentric = value of species independent of their usefulness to humans
anthropocentric = value of species depends on usefulness to humans
28
what are ecosystem services of biodiversity?
pollinating flowers (majority of global crops rely on pollinators)
stabilizing climate
soil formation
controlling pests
29
what is the importance of biodiversity in agriculture?
important for food security in case of failure, has declined over time from selective breeding
30
IPAT equation
impact = population x affluence x technology
31
human threats to biodiversity
habitat conversion, habitat fragmentation, hunting becoming its own form of "natural selection" reversing actual natural selection by killing ones that have favorable traits to survive in the wild, predator control, wildlife trade
32
4 criteria for preserving biodiversity
1. uniqueness (unique genetic composition)
2. usefulness (commercial or cultural value)
3. probability of extinction (how much effort is necessary to save the species)
4. cost (to save the species)
33
in-situ vs ex-situ conservation
in-situ preserves species in natural habitat, ex preserves genetic material and conducts researchm
34
market based solutions to preserving biodiversity
ecotourism (contributes to conservation, operated with local communities for benefit)
biodiversity offsets - when development destroys habitat, a newer, bigger, better habitat must be restored/built
humans should act as land managers
35
null vs alternative hypothesis
null = no effect or change
alternative = discernable change
36
type I vs type II error
type I = false positive, rejects null hypothesis that is true (finds alternative hypothesis correct when it isn't)
type II = false negative, accepts a false null hypothesis (shows no difference when there is)
37
weather vs climate
weather = temperature, precipitation, wind speed, cloud cover, humidity, pressure (at a particular time and place)
climate = patterns of weather conditions across an annual cycle
38
short wave radiation vs long wave radiation
short wave = light energy
long wave = infrared, sensible heat
short wave is reflected back as long wave & absorbed by GHG
39
atmospheric GHG
water vapor, CO2, methane, CFCs HFCs
40
radiative forcing
GHG potency determined by amt and frequency of infrared radiation it can absorb
41
what are the 2 largest sources of GHG?
electricity & heat production
42
aerosols
sulfates form aerosols (particles suspended in the air smaller than droplets) that reflect sunlight (short wave radiation), leading to cooling
43
why can't CO2 fertilization happen indefinitely?
as heat becomes more of a limiting factor, there will be a slowing down of net absorption
44
what causes sea level rise (and what are some effects)?
melting of ice sheets on ground into ocean, water expands as it warms, increased runoff, storm surges have increased damage, natural tides are disrupted, subsidence (sinking of land under built cities)
45
4 categories of ecosystem services
supporting (nutrient cycling, soil formation, primary production)
provisioning (food, water, fiber, fuel $ value)
regulating (climate, flood, disease, water purification)
cultural (aesthetic, spiritual, recreation)
46
forest characteristics (state factors vs stochastic factors)
state = time, topography, parent material, climate, biota (expected state of ecosystem)
stochastic factors = extreme climate events, irruptions of native biota (push away from expected state)
47
forest ecosystem services
water quality, carbon storage, biodiversity, habitats, raw materials
48
why is snow important?
it provides insulation for soil and prevents it from freezing; lack of snow results in freezing, root/microbial mortality, accelerated nutrient loss & soil acidification
49
role of earthworms
invasive species from europe, they cause fundamental changes in soil properties: decrease soil, more vulnerable to erosion, diff seed bed, exposed roots
50
DISservices of forests
prevent agricultural land, opportunity costs, species invasions, forest fires
51
cut-down services of wood
materials (developed nations) & source of energy (developing nations)
52
standing service of wood
climate regulation, soil conservation, biodiversity
53
how do forests affect climate?
trees shape local temp and water availability through albedo & transpiration; removing them could heat or cool surroundings
less evaporation at a lower ambient temp, perform less photosynthesis from shorter growing system
- in short, influences rate of absorption of solar energy & at which water evaporates from the surface
54
how does moisture cycling work?
critical mechanism for rainfall to reach western amazon,
prevailing winds cause rising and cooling air & precipitation, evapotranspiration by trees contributes to precipitation
55
what are local rates of deforestation associated with?
conversion of forests to agricultural land, timber harvests, fires (accidental & deliberately set), energy & mineral production
56
water flow regulation in forests
| floods
trees/plants slow soil erosion, less trees --> less soil retention, fast flowing water creates floods and carves channels, erodes soil & sediment with it
57
primary forest vs secondary forest
primary = late successional native forests containing most carbon and biodiversity
secondary = still regrowing, less biodiversity, less total C stock than primary forest but faster C sequestration rates
58
feed conversion efficiency
ratio of edible calories of animal product produced per cal of feed consumed by animal
FCE = cals of edible food produced / calories of feed consumed
59
does management of forests w/ continuous harvests increase or decrease the prevalence of forest fires?
INCREASE; harvest forests are not the same as wild intact ones: uniform rows, diff community composition, monoculture, same size/same age trees (one vulnerable, all vulnerable); continuous harvest increases dryness, increases winds, newly planted trees are not necessarily fire adapted
60
when does deforestation occur?
when the value of cutting timber or using the land for other purposes is greater than the value of leaving it standing (rent)
61
market based policies for forest protection
protected areas
mandate logging
conversion tax
paying landowners a fee equal to value of ecosystem services,
eliminating subsidies that inflate economic benefits,
debt for nature swap
62
how does short wave radiation become long wave radiation?
they turn to long as the waves lose frequency from absorption, the long wave then releases heat
63
extensive use vs intensive use
extensive = using lots of land with relatively few inputs, occurs in areas of low pop density & on threshold of hunting/gathering ex. cattle ranching
intensive = lots of input relative to the amt of land
(the ratio to work done and resources used), occurs where good agricultural land is very scarce and labor is abundant
64
what are the 2 main sources of biofuel in brazil?
soy and corn
65
fossil fuel creation
diagenesis (process that describes physical and chemical changes in temperature under pressure)
catagenesis (turns decomposed material into coal, further burial resulting in higher pressures and temperatures)
66
where does freshwater come from and how much is available to humans?
evaporation is responsible for most freshwater formation; 2/3 is frozen, 2/3 is inaccessible underground, 1% available to use
67
hydrological cycle
water moving through pools start with oceans (largest stock), saltwater = unavailable, evaporation heats water in ocean, condenses into droplets & clouds, falls as precipitation; the movement of water is changes in location and state
68
residence time equation (water)
for a steady state system, reservoir volume / inflow or outflow rate; in steady state, inflow = outflow
T = volume / flux
69
infiltration vs percolation
infiltration = water getting into groundwater; infiltrating water hits an impermeable layer ex. clay or bedrock
percolation = water passing through solids, impermeable rocks
70
saltwater intrusion
saltwater mixes with water in water table
71
aquifer
where water accumulates by filling all pores underground & makes the spaces between pores wider
72
what is the top of an aquifer?
water table
73
what is capillary range & recharge area?
the area where groundwater is drawn up into the pores in the sediment by capillary action
recharge area = land area whose groundwater flows to the aquifer; the rate at which water infiltrates (and groundwater recharges) is relatively slow --> causes problems when used as a resource
74
characteristics of groundwater
exists underground in saturated zones beneath land surface filling pores and fractures in sediments and rocks, moves slowly, residence time of groundwater in aquifer can range from 100s-1000s of years
75
runoff
water that does not infiltrate soil & moves across surface; follows topography to nearest surface water
76
why is ocean water so salty?
when water flows over land, it gathers minerals from rocks and carries it to ocean
77
how does surface water increase?
construction of reservoirs/dams & melting of glacial ice
78
why is the distribution of water uneven?
does not fall evenly across world due to hadley cells; theres great variation in water availability per person depending on where you live
79
importance of human water management
they represent mechanisms to reduce variability: man-made reservoirs, dams
80
characteristics of anthropogenic landscapes that make water pass faster
gray infrastructure, impervious surfaces can make effects of flooding more severe, can be managed by dams & reservoirs because they fix mix-match in time
81
water storage vs water diversion
storage = dams, reservoirs
diversion = canals, aqueducts
82
desalination techniques & downfalls
thermal desalination = boiling
membrane desalination = basically filtering the water so that salt molecules get separated
expensive, requires lots of energy
83
how do dams help water management? what are some benefits?
regulate water availability by storing floodwaters and allowing for controlled release
form of risk management, correcting mismatch between supply & demand for water overtime
irrigate soils & flood regulation
84
negative effects of dams?
land rights (affecting downstream flow, whose land is getting flooded, table lowering), benefit upstream users at expense of downstream, flood communities, disrupt sediment transport, disrupt migration of fish, displace and destroy seasonally flooded ecosystems
85
artesian wells vs unconfined aquifers
groundwater confined between 2 impermeable layers is under pressure, flows up through well without need for pump (favorable)
unconfined aquifers are more common & not under pressure, require a pump to get water
86
do cones of depression occur in artesian wells?
no, because they occur as a result of the pumping of an unconfined aquifer, aka water pumped out at a faster rate than the rest of the groundwater can move through the soil to replace it which leads to water withdrawal)
87
problem with unconfined aquifers
heavy pumping combined with slow lateral flow of groundwater causes aquifer level to drop --> leading to cone of depression --> forcing pumps to work harder
88
what is offstream water/its uses?
waterworks provide water for offstream use, water diverted or withdrawn from surface or groundwater;** uses are classified as withdrawal/consumption aka water removed from source (consumption = withdrawal - discharge); water returned = discharge**
89
how does affluence affect water allocation?
withdrawals differ within & between countries because denser nations require more water; developing countries use water for household & agricultural practices, developed countries = industrial & energy
90
categories of offstream water use
agriculture (irrigation),
industry (used as a solvent, coolant, transport agent)
municipal (basic needs, lawns, swimming pools, car washing, running buisness)
energy (massive quantities of water for steam generation & cooling)
91
instream water uses
shipping, hydroelectric energy, recreation, env regulation & services
92
how does hydroelectric energy work?
water builds up behind a dam accumulating potential energy --> transformed into mechanical energy, water rushes through penstock spinning a turbine which powers a generator --> electricity
93
when does mining groundwater occur?
caused by negative recharge rate in overstressed aquifers & stressed aquifers that have a positive recharge rate but smaller than the rate at which water is removed
94
how can mining groundwater be sustainable?
the recharge rate must exceed the rate of pumping;
95
what happens when water is withdrawn faster than its replenished?
withdrawing faster than its replenished --> lower water table --> lower river water level
96
withdrawal vs discharge
water removed from source vs water returned (often near or at source)
97
why would more groundwater use be better for shallow aquifers?
flood waters will be better able to infiltrate and be saved
98
cones of depression
occur as a result of excessive pumping of an unconfined aquifer in which water is pumped faster than the groundwater can level out to replace what is being pumped out, leading to a lower water table
99
what are negative effects of pumping unconfined aquifers?
pumping becomes more expensive & pumping deeper can mean liberating harmful contaminants and pumping them to surface
100
cones of intrusion
in coastal context the void left by groundwater can exacerbate saltwater intrusion, making agriculture more expensive & difficult
101
how does water pollution occur?
discharging of pollutants into water, coolant water can be polluted because its too warm to be used by ecosystems or it picks up metal contaminants, leaking of pollutants into water supplies, fertilizers from farms & manure
agriculture = nonpoint
industrial = point
102
xenobiotics
human manufactured organics that arent readily broken down in env
103
what are green tides?
microbial algae blooms linked to nitrates in fertilizers and waste from regions
104
riparian water rights
assign a share of water flow to all parties whose land borders a surface water flow, but does not allow parties to divert water
105
prior appropriation doctrine
earliest users of water have the highest priority rights, later users have their rights curtailed during shortages
106
reasonable use doctrine
allows landowners to pump water for any beneficial use, doesn't recognize priority
107
groundwater rights
harder to define, since aquifers are not well cataloged and water tables are difficult to observe
108
who pays less for water?
earliest users such as mining and agriculture firms (and use the most) vs household and municipalities
109
carbon stocks vs flows (effects)
atmosphere, ocean, permafrost, vegetation
vs
from ocean to atmosphere --> ocean acidification, coral bleaching
110
why is water used inefficently?
because prices vary among users and rarely include all costs
111
what are some of the most negative consequences of agriculture?
largest cause of land change, deforestation, freshwater withdrawals, biodiversity loss, 1/4 -1/3 of GHG emissions
112
how did modern agriculture start?
last ice age created fertile conditions that were conducive to agriculture; it arose independently in diff areas in response to diff env opportunities
113
technical change hypothesis
agriculture emerges with increased human technological capacity, better knowledge & tools over time
114
coevolutionary hypothesis
agriculture emerged in a positive feedback loop w/human activity, starting with initial clearing of trees and creation of cultivable species
115
resource depletion hypothesis
hunting gets more difficult over time from best first principle; EROI of hunting is favorable at small population density, EROI of agriculture is favorable for large pop density
116
how did agriculture spread & why?
from east to west because of gradients, and the spread of farming techniques to areas with similar climates, precipitation, and radiation across latitudinal bands (SIMPLY: similar latitudes have similar precipitation, temperature, and radiation)
117
what are the 7 steps for converting natural ecosystems to agriculture?
1. clearing land
2. sowing seeds
3. fertilizing soil
4. irrigation
5. suppressing succession (weeding)
6. pest control (weeds, fungi, insects)
7. harvest
118
what type of species are vegetables?
r-selected
119
what is the slash and burn method& what is it characterized by?
a method under extensive agriculture in which small swatches are cleared for agriculture by burning; characterized by short periods of cultivation, long fallow periods to allow for forest regrowth; it's sustainable as long as fallow period is sufficiently long and land is abundant relative to population
120
what are postive and negative effects of clear cutting?
negative:
soil erosion, loss of habitat, unwanted plant species
positive: reduce harvesting costs, speeding regrowth of forest
121
what would a sustainable yield of timber look like?
harvesting no faster than the rate at which trees produce new supplies
122
what characteristics are necessary to switch to intensive agriculture?
as pop grows denser, richer, and more technologically advanced, where land is abundant relative to labor
123
mechanisms created by green revolution
increased mechanization, new fertilizer technology (haber bosch process), high yield cultivars (genetic modification), irrigation
124
how can crop yields be improved?
increasing NPP
improving allocation of energy to edible plant parts
gmos
125
selection pressures applied through humans selective breeding have led to (developing cultivars):
shorter plants, thicker/longer stalks, more or larger grains, more energy allocated to production of germs
126
what is "closing the yield gap" in agriculture?
farmers getting as close as possible to theoretical max yield with new inputs like new technology & breeding
127
what was the green revolution impact on land?
increased food production intensity prevented agricultural expansion that may have otherwise occurred, likely sparing native biomes from MORE tilling & deforestation than would be happening rn
128
if there is enough food to feed the entire world, why are there still starving people?
problems related to poor market access, high prices
129
describe a positive feedback loop in agriculture
increased human population increases the amount of land that needs to be cleared which increases the amount of edible plants grown which increases human population
130
what were some economy impacts of the green revolution?
cut food prices, ppl better nourished but not evenly spread across globe, facilitated economies of scale through mechanization and inputs, freed ppl to do other jobs when smaller farms were bought out (if there are other jobs to do)
131
why does monocropping require more pesticides?
there is less diversity since they have been selectively bred to have certain traits, there is little to no genetic variation, and planting one species vs multiple also contributes to lack of diversity; both make them more susceptible to disease or pests
132
what were environmental impacts of the green revolution?
fossil fuel use, waste, chemical footprints increased to support machines, fertilizers and pesticides to support MONOCROPPING
eroi now about 1:10 (basically much less energy used to create food than energy produced from that food, more efficient)
more food but more eutrophication, GHG emissions, pesticide resistance
133
integrated pest management
applying pesticides in fewer and more precise quantities, works with natural pest-predator ecosystem structure in surrounding environment
134
precision nutrient management
reduce and adjust fertilizer to be more precise with needs of crops and local weather, planning for rainstorms that would cause runoff
135
what are the four r's of improving agricultural production?
right rate, right source, right application method, right application timing
136
what were dietary changes created by the green revolution?
development of oversupply of unhealthy refined grain cereals, feeding surplus grains to animals --> surplus livestock production, lowering costs
increased meat consumption
137
where do most GHG come from in food production?
production
138
where do fewest emissions in food production come from?
post production
139
what emissions are expected to go down in food production?
livestock emissions per unit, CO2 from land clearing, CO2 from soil tilling and oxidation, emissions per unit food
140
what emissions are expected to go up in food production?
total livestock emissions, total food emissions, methane from manure, rice fields, food waste in landfills, CO2 from transport, manufacturing, N2O from fertilizer and manure
141
sources of food system CO2
deforestation, tilling, peatland drainage, fossil fuels for transport, inputs in manufacturing
142
sources of food system CH4
cow burps and manure management, rice production, waste in landfills,
143
sources of food system N2O
fertilizer and manure, increased legume production
144
what are effects of livestock production?
deforestation & land clearing, biodiversity loss, soil erosion & pasture degradation, pesticide and fertilizer overuse (from increased animal feed), freshwater depletion, pollution, eutrophication, air quality degradation
145
why did the aral sea shrink?
when using more water for irrigation than there is going back into the sea, as a result there's lower water flow and more sediments are dropped
146
explain a pos and neg feedback loop in climate change
positive:
rising temp leads to melting of ice caps, thus lower albedo, less radiation being reflected, more radiation absorbed, thus increase in temp
OR
rise in temp will thaw permafrost --> releases CO2 --> further inc temp
negative:
temp increasing --> more evaporation --> more water vapor --> more clouds --> more reflective surface --> increased albedo --> dec temp
147
which GHG have highest radiative forcing/residence time?
water vapor has highest radiative forcing, carbon has longest residence time
148
identify which parts of the equation pertain to their respective parts in the IPAT:
CO2 = population x (GDP/person) x (CO2/GDP)
impact = increased CO2 emissions
affluence = GDP/Person
technology (efficiency) = energy/GDP
