Environmental Science Midterm 2 Flashcards
Midterm 2 (184 cards)
1
Q
How were Asian Carp introduced into the river?
A
Brought from china to eat algae and clean up ponds but they escaped into the wild ( Mississippi River)
2
Q
What makes asian carp a good invasive species?
A
- highly adaptive
- lots of offspring
3
Q
What is I = P x A x T ?
A
I = Impact
P = Population size
A = affluence - rich generally have more impact, consume more, more space
T = technology - can exacerbate or decrease impacts
Our individual human impact
4
Q
What is demography?
A
- the application of ecology principles to the study of statistical change in humans populations
- it is a social science
5
Q
What is the formula for population growth? Growth rate ?
A
P2 = P1 + (Births - Death) + (immigration - emmigaration)
growth rate (%) = (number added/pi)x100
6
Q
how many growth spurts has the human population had? What is the population on track for in 2100?
A
- 2 growth spurts (agricultural revolution and Industrial Revolution)
- 21 billion by 2100
7
Q
What is zero-population growth ?
A
- the absence of population growth ; occurs when birth rates = death rates
- will result in population stabilization
8
Q
What growth curve is the human population? at what percentage is it increasing? What is the doubling time?
A
- exponential (1.12%)
- 70/1.12 = 63 years we will be at 15,200,000,000
9
Q
What would the growth rate need to be to have no population growth?
A
Zero
- even if there is a decline in growth rates, the population is still growing but more slowly than it did before
10
Q
Is the distribution of the population even?
A
no, wildly uneven (clumped)
-59.5 % in Asia alone
- populations are located close to the ocean or major rivers
11
Q
What percentage of the population are in 10 nations?
A
60% in just 10 nations
- china and india most populous, in 2023 India passed china as the most populous country
12
Q
What are some factors that determine human population size?
A
- birth, death, emigration, immigration
13
Q
What are demographic factors?
A
population characteristics such as birth rate the influences changes in population size and composition
- population growth factors and population RESISTANCE factors
14
Q
What is desired fertility? TFR? What is their relationship?
A
- Desired fertility: the ideal number of children an individual indicates he or she would like to have (influenced by health, education, economic conditions, culture, and religion)
TFR: total fertility rate: the number of children the average woman has in her lifetime (2019 TFR=2.5)
- TFRs are highly variable place to place
- relationship: generally as desired fertility increases so does TFR
15
Q
What are pronatalist pressures?
A
- factors that influence population growth
- high infant mortality rates, lack of education or job opportunities for women, valuing children (labour, religion, cultural), unmet needs for contraception
16
Q
What are some relationships between pronatalist factors and social justice?
A
- childhood mortality and TFR - closely related to poverty, more death = more children
- education of women and TFR: fertility declines as educational opportunities for girls and women increase
- contraceptive use and TFR: access to contraceptives and family planning have been effective in many areas of the world
–> however, in countries with high desired fertility such as niger providing contraceptives may have little impact on TFR
17
Q
Describe the demographic transition graph
A
–
18
Q
How does age structure help predict growth?
A
- we can see that births and deaths that predict whether a population will have high birth rates
eg; madagascar has a lot of children, they keep reproducing, die earlier
19
Q
Is the demographic transition a universal process?
A
- Canada, Japan, US have followed this model
- why might industrialization not lead to a demographic transition in all countries? -No contraception, religious beliefs, fewer rights for women, disease in countries keeps death rates high,
20
Q
What is an ecological footprint?
A
- a measure of one’s consumption and waste production expressed in land required per person
(I = P x A x T)
21
Q
When did the human population exceed earth’s carrying capacity?
A
in 1970 we began to use more resources than earth could replace long term - not sustainable, cannot continue indefinitely
22
Q
What might increase our footprint?
A
- wealth produces severe and far-reaching environmental impacts ( buy more stuff, drive, take up more space, create more garbage, more emissions, etc, etc)
23
Q
What are some methods to reduce the population growth?
A
- population and carrying capacity is complex
- to be truly sustainable: must address key components address components such as poverty, education, improving basic human rights
- those with greater affluence must reconsider their lifestyles and impacts
24
Q
What are invasive species?
A
- a species which has been introduced intentionally or accidentally from one place to another
- most organisms introduced to new environments perish but few survive and do well
25
What are some characteristics of invasive species ? Provide one example of invasive species and why they were successful
- lacks predators, spreads widely, and becomes dominant in communities outcompeting native species
- exotic or alien, not native
- asian carp fish: introduced from china to remove algae in ponds - soon escaped: very adaptable, big problem
26
Why is freshwater threatened?
- a limited resource we are using faster than can be replenished
- although methods available for recovery and purification conservation needed
27
How much freshwater is on earth? How much saltwater? How much is usable?
97.5% saltwater, 2.5% fresh, only 1.2% is usable
28
What are placed where water is stored called? what is the process called when this water moves?
Pools
- the ways that water moves between pools are called fluxes
29
Provide examples of pools and fluxes?
pools: ice sheets/glaciers, lakes, ocean, wetlands(brackish), permafrost, atmosphere, soil moisture, rivers, groundwater
Fluxes: snowmelt, rivers(stream flows),infiltration, , evaporation + precipitation + transpiration (evapotranspiration), runoff, ocean circulation, groundwater runoff
30
What drives the water cycle?
- mostly energy from the sun and gravity (sun drives evapotranspiration and wind, gravity = flows)
- human processes too
31
How are humans altering the water cycle?
- develop land, agriculture, industries uses a lot of water, climate change (drought), dams, domestic use
32
How will climate change affect the water cycles?
- stronger storms: flooding, water in atmosphere
- flooding due to melting snow, glaciers, and permafrost
- melting permafrost
- less access to drinking water
- drought
33
What is water pollution?
The addition of any substance to a body of water that might degrade its quality
- eg; oil spills, sewage, lead, plastics, arsenic, salt
34
What are the two major causes of water pollution?
1) Point sources: Some industrial and agricultural discharge and pollutants directly into a body of water
- has a direct, identifiable source
2) Nonpoint sources: a variety of sources contribute pollutants that can run off surface of the land during rainfall and enter the water; air pollutants can fall directly with rain
35
What are the two leading causes of impaired surface numbers?
- oxygen depletion and mercury
36
What are some components that are measured in water monitoring?
- physical: temperature, oH, turbidity
- chemical: nutrients and chemicals
- biological: benthic macroinvertebrates
- process of biological assessment: includes netting, identifying and counting benthic macro invertebrates: Can measure biodiversity and species richness to determine if anything is impacting water ways
37
What is nutrient pollution?
- excess phosphorus and nitrogen from surface runoff leads to eutrophication
- oligotrophic water body vs. eutrophic water body
38
What defines an unhealthy body of water?
Describe the steps of eutrophication
- high algal and bacterial growth, low dissolved oxygen, and loss of some aquatic life
1. Nutrients cause algal blooms
2. Less sunlight can penetrate the algal blooms and sediments
3. underwater photosynthesis decreases, plants die, oxygen levels drop
4. as algae die, decomposers increase in number and use more oxygen causing dissolved oxygen levels to drop even mire
39
What are some substances of toxic chemical pollution?
- pesticides, petroleum products, metals, acids, synthetic materials, many chemicals soluble and some fat soluble
40
What factors determine how toxic water pollutants are to living beings?
1. Potency: how much or how little is needed to cause harm
2. persistence or degradability: How easily it breaks down into its constituent parts
3. bioavailability: the ability of a chemical to be absorbed by an organism
41
What is solubility? What are the two forms of solubility as it pertains to bioaccumulation?
Solubility: how long a chemical stays in our body is affected by its solubility
- water soluble and fat soluble
42
which form of solubility is more harmful? why are they both the way they are?
- fat soluble is more complex: cells can absorb these chemicals and once inside our bodies have a hard time expelling them - they can build up in our fatty tissue and become toxic (mercury build up in top predators)
- water soluble is less harmful because the kidneys can extract water soluble chemicals from the bloodstream and excrete them through urine
43
What is bioaccumulation? Biomagnification?
- bioaccumulation: Occurs in the individual, a build up of toxic chemicals in animals as they get older (a fish accumulates some mercury every day, the longer it lives the more accumulated)
Biomagnification: A food chain phenomenon
- the higher up the food chain the more chemical buildup (top predators have high mercury content)
44
What are some natural sources of mercury in the environment?
- natural: volcanoes, weathering of rocks, forest fires, soils
- coal burning power plants+ industrial processes are most common anthropogenic sources of mercury pollution (coal contains mercury)
45
What are the two forms of mercury?
- Hg: elemental mercury (inorganic) - not bioavailable
- CH3Hg+ : methyl mercury: organic, bioavailable
- highly toxic, gets into the food web
46
What is mercury methylation?
- bacteria convert inorganic mercury to organic form methyl mercury
47
What are the steps of mercury form alterations?
50%-70% from anthropogenic sources, released into atmosphere as Hg - deposited on land and into water - mercury in river/lake sediments are converted be bacteria into methyl-mercury (gets accumulated into food chain)
- know the diagram!
48
Review the tuna and mercury accumulation reports from class are study
49
What percentage of land is covered in forest?
What amount of forest have we lost in the last 300 years?
- 25% of land is covered by forests
- in the last 300 years we have lost 35% of the world's forests
50
What climactic factors affect forest biomes? What are the kinds of forest biomes? Where are they found?
- temperature, precipitation, moisture
- tropical (South of the equator, lower latitude), temperate ( N and S of equator, mid equatorial), boreal forests (N of the equator, higher latitude)
51
Describe the boreal forest?
AKA taiga
- largest terrestrial biome, high elevations, high latitude, short growing seasons, acidic soils
- major trees are evergreens (makes sense due to short growing season and conditions ; pine needles fall to ground and acidify soil)
52
Describe the temperate forest?
- distinct seasons, fertile soil, rich/diverse plant life, trees are predominantly evergreens and deciduous
- as leaves of decision trees fall tog round nitrogen is restored to soil every growing season: rich soil
- higher diversity of trees than the boreal forest, some evergreens still present
- historically home to large predators among other species
53
Describe the tropical forest
- similar year-round temperatures *dry have a wet and dry season, wet tropical rainforest wet all year round*
- soils thin and low in nutrients - rapid decomposition supports dense vegetation
- low nutrient content because they are mostly held in plants to support rapid growth (so many plants that all require nutrients, nothing left in soil)
54
what are the cross sectional areas of the forest?
- emergent layer, canopy, understory, forest floor
55
What makes forests important to carbon and cultural values?
- carbon storage helps climate changes and nutrient cycles
- culturally: 200+ indigenous communities live in rain forest, significant for connections to nature and leisure
56
What are urban forests? Describe their benefits
- urban forests (like point pleasant) are forests within cities
- provide air and water purification, absorbs noise dust and co2, provides shade, energy, and reduces extreme temperatures, provides habitat for animals, and helps prevent flooding (re: Halifax groundwater and sewage system)
- reduces mental health problems, helps post op recovery,
57
What are some ecosystem services provided by forests?
- food, resources (economy, jobs), ecotourism, water purification (water cycle), carbon storage, nutrient cycling
58
Provide a brief history of deforestation
- near east, Greece, Roman Empire cut forests before the modern era
- removal of forests continued north in Europe as civilization advanced
- great britians forests were cut and many forest areas eliminated
- colonization of new world: much of North American forests cut (originally held of NA was forest)
59
Where does the majority of deforestation occur today?
- in developing nations
60
Describe the history of deforestation in Canada and the US
- growth of these nations was fueled by land clearing and logging
- cleared land for agriculture from east to west
- wood used to fuel furnaces of industry
- deforestation propelled societal and population growth
- Principle cause of deforestation in Canada is agriculture
61
What are some reasons for deforestation? What are some methods or events that may cause deforestation?
- harvesting forests for wood/wood products, fuel in developing countries, clearing land for agriculture, and clearing land for urbanization / energy for cities
- pest infestation, cattle ranching, fires, large farms, roads, charcoal/firewood
62
Why are deforestation rates lower in high income countries?
- major industry still involves deforestation but we are managing and restoring forests now as we have the financial and established capabilities
- attempts to manage forests suitably in Canada while our life styles are still very much led by deforestation in other nations
63
What are the 3 methods of harvesting?
Clear cutting, selective harvesting, shelterwood harvesting
64
What is clear cutting?
- timber harvesting that cuts all trees in an area, very damaging
- can cause flooding and local climate change, muddy waters as erosion pollutes water
- immediate profit but then no profit as forest regenerates
- low biodiversity, in tree farms still erosion but less than in clear cut
65
What is selective harvesting?
- cuts only highest value trees and allows remaining trees to reseed the plot
- more environmentally sound, used in temperate forests, some more work for prepping and harvesting
- biodiversity less than natural forests but better than clear cut, waters are undisturbed (they do not cut trees by river)
- intermediate profits, forest quality may gradually decline
66
What is shelterwood harvesting?
- cuts all but the best trees and allows them to reseed the plots
- more environmentally sound, done in temperate forests
- profits similar to selective BUT increase as higher quality trees grow / reseed
- mixed age multi species tree stand: additional income, biodiversity increases as forest grows, may be higher than any other harvested stands
67
Do any methods of harvesting not impact the habitat?
nope, all methods disturb the habitat - change forest structure and decomposition - decrease biodiversity: increase erosion, siltation, runoff, flooding, landslides
68
What percentage of economy and energy do forests provide in Haiti?
- 20% responsible for rural economy, 80% of energy
69
What are the two methods to manage forests sustainably?
- maximum sustainable yield and forest ecosystem management
70
What is maximum sustainable yield?
- harvesting as much as is sustainably possible (but no more) for greatest economic benefit
- early focus of national forest service
71
What forest ecosystem management?
- system that focuses on managing the forest as a whole rather than for maximizing yields of specific product
- utilizes a variety of techniques for harvesting, vegetation removal, controlled burning
72
What are some methods to protect the forests?
- payment for ecosystem services - encourages protection of natural areas while promoting economic benefits
- intrinsic value of natural forests translated into income through tourisms: the forest isproteted and local economy continues to earn income from tourism
73
What solution to Haiti's deforestation must it require?
- an alternative to charcoal
- fast growing trees which can be pruned (Forest Stewardship Council alternative energy source)
74
What are the 5 strategies to protect forests?
1. Assign monetary value to forest ecosystem services
2. sustainable harvest of forest products
3. use alternatives to wood for products and fuel
4. designate forests as protected areas
5. promote ecotourism
75
Do trees clean water?
Trees themselves do not clean water but provide soil stability which filter water
- also Phytoremediation is where the tree roots can clear contaminants from the soil
76
What is Nova Scotia's 2030 forestry goal?
to protect 20% of Nova Scotia's land and water by 2030
77
What is water pollution?
- the addition of any substance to a body of water that might degrade its quality
- eg; oil spills, sewage, lead, plastics, arsenic, salt
78
What are the 2 primary causes of water pollution?
- Point source pollution: certain industrial/agricultural sources discharge pollutants directly into bodies of water (has a direct, identifiable source)
- Non-point source pollution: a variety of sources contribute pollutants the can run off surface of the land during rainfall and enter the water ; air pollutants can fall directly with rain
79
What are the two leading causes of water pollution in Canada?
- oxygen depletion and mercury contamination
80
- What are the 4 methods of water quality monitoring?
- physical: temperature, PH, turbidity
- chemical: nutrients and metals
- Biological: benthic macro invertebrates (biological assessment)
- community based initiatives: communities monitor their own waters
81
What are the steps to biological assessments?
- a kick net with weights is placed against stream bottom in front of a shallow part of the stream
- ahead of the nets rocks are knocked together to dislodge invertebrates who flow into the net
- debris is searched for aquatic organisms - the visit and abundance of aquatic life are tallied to rate streams in terms of water quality
this process measures the biodiversity and species richness to determine if anything is impacting the water ways + the water qualit
82
what is nutrient pollution?
- excess phosphorus and nitrogen from surface runoff leads to eutrophication
83
What is a healthy body of water?
- low nutrient levels, algae in check, good DO, abundant species: water is clear and sunlight can enter and photosynthesize all plants
84
What is an unhealthy (eutrophication) body of water?
- high algal/ bacterial growth, low DO, loss of some aquatic life
1) nutrient excess = algal bloom
2) less sunlight can penetrate algal blooms/sediments (high turbidity)
3) underwater photosynthesis decreases, plants die, DO drops
4) dead algae increases abundance of decomposers who use more oxygen and deplete DO even more
85
What causes toxic chemical pollution?
- pesticides, petroleum products, metals, acids, other synthetic chemicals
86
What factors determine how toxic a water pollutant is?
- 1) potency: how much or little is harmful
2) persistence or degradability: how easily it breaks down into its components
3) bioavailability: the ability of a chemical to be absorbed by an organism (if its dissolved in water it has high bioavailability)
87
What is solubility? What are the two forms of solubility discussed?
- how long a chemical stays in the body is effected by its solubility and under which conditions it dissolves
- waster soluble: kidneys can extract water soluble chemicals from bloodstream and extract them through urine
- fat soluble: more complex -cells can absorb these chemicals and once inside our bodies have a. hard time expelling them - build up in fatty tissue, become toxic
88
What is bioaccumulation?
In individuals levels of chemical increases every day as they get larger - the build up in one individual
89
What is biomagnification?
- a food chain phenomenon : top predators accumulate more mercury due to their prey having more mercury than the lower down trophic levels
eg; otters eat cod which have a greater accumulation of mercury than phtyoplankton do
90
What are some descriptors of tuna?
- apex predators, long lived (>30), increasing global demand and higher consumption increases risk of exposure to chemicals like mercury
91
What are some anthropogenic and natural sources of mercury?
- natural: volcanic activity, soil, rock weathering, forest fires,
- anthropogenic:: coal burning power plants and other industrial processes, coal contains mercury and when burned mercury released into the air
92
Which industry in canada is most responsible for mercury output?
- ore and mineral mining industry
93
What are the two forms of mercury? are they bioavailable?
- Hg : elemental mercury - not bioavailable (in air, elemental version not able to be uptaken by living organisms)
- Methyl mercury CH3Mg+ - bioavailable (able to be taken up by living organisms)
94
How does mercury get turned into methyl mercury?
- bacteria convert inorganic mercury into the organic form methyl mercury
95
Describe the mercury cycle as it enters the ecosystem
- 50-75% of nitrogen comes from anthropogenic sources --> Hg in emissions (released when burned) --> Hg deposited on land and into water --> bacteria converts into methyl mercury -->adsorbed onto phytoplankton
--> Zoo-plankton --> small fish --> big fish (bioaccumulates and biomagnification)
96
Why does mercury build up in organisms?
- because it is fat soluble
97
Be familiar with the FDA case study: mercury in fish
98
Why do we care about soil?
- soil is the future: could be the solution to climate change
99
What are the connections between aspects of soil?
- growing human population --> must eat --> agriculture is the best for providing this food --> healthy doily essential for agriculture --> is soil a sustainable source? (yes if handled sustainably)
100
Is soil sustainable?
- yes, if managed responsibly!
101
How is soil connected to the elements of the earth systems?
- involved in all systems: biosphere, geosphere, hydrosphere, atmosphere
102
What makes soil a living thing?
- living, breathing, nutrient rich medium
- has microorganisms: important for carbon, nitrogen, phosphorus cycles
- agriculture, forestry, etc
- soil involved in all levels of planet
103
What is soil?
- typical agricultural soil : but soil varies from location to location: composed of stuff lol
104
What are the processes of soil formation?
1. weathering
2. erosion: deposition of soil to new area
3. biological inputs and decomposition
105
What are the 5 main factors that influence soil formation?
function of CLORPT
- climate, land relief, organic material, contribute to parent material which over time become soil
106
What is parent material? How long does parent material transformation take?
- bedrock under soil - minerals that undergo weathering - eventually turn to soil
- may take decades to millennia to turn to soil depending on conditions
107
What is weathering? What are the forms of weathering?
- the process by which larger rocks are broken into smaller rocks
- chemical weathering and biological weathering and physical weathering
108
What is physical weathering?
- no chemical change involved, climate affects rate, an accelerating process
- wind, rain, water, freezing etc: physical natural conditions which cause weathering
109
What is chemical weathering?
- breakdown of minerals by chemical reaction, carries minerals away in solution to form new materials,
eg; calcium dissolves in water leaving voids, feldspar turns to clay
110
What is biological weathering? Provide two examples
- mediated by living things
- eg; tree roots break up rocks, chemicals from plant litter/roots may accelerate weathering
111
What are the two forms of parent materials?
Residual: parent material weathered in place, building up over millennia
transported: parent material eroded, transported, and deposited
112
What is deposition?
- organic matter accumulation (eg; dead bodies and organic waste)
- organic matter incorporates into substrate mixing with materials
113
what is decomposition?
- detrivores, millipedes, and soil insects scavenge on waste products and dead bodies
- decomposers bacteria and fungi : complex organic molecules broken down to simpler forms which can be taken up by plants through their roots
114
What is humus?
- partially decomposed organic matter
- dark spongey crumbly mass of material made up of complex organic compounds
- helps soil hold moisture
- productive for plant life
115
What are the 17 (!) essential elements for plant growth?
- carbon, hydrogen, oxygen can be obtained from air and water
- N, P, K, S, Ca, mg are the soil derived macronutrients
- there set are solid derived macronutrients B, Cl, Cu, Fe, Mn, No, Ni, Zn
- Carbon in soil ; soil rich store of carbon
116
What is erosion?
- forms soil in one area by depositing material it has depleted from another
- the transport process can promote physical weathering
- often destructive reducing the amount of life in given are can support
- removes nutrient rich top soil
117
What is splash erosion?
- soil moves through splashing or falling in an area
118
What are soil horizons?
- sorting of mineral particles by wind, water, and organisms
- layers develop horizons
- cross section of soil; soil profile
119
What is soil structure? What determines soil structure?
- relates to the soils tenancy to form lumps or clods of soil particles called PEDS
- has many different structures: ideal is mixed (peds)
120
What soil components are ideal?
- peds : )
121
What are the soil horizons? Describe them!
- O horizon: Surface - litter
- B horizon: top soil - contains decaying organic matter (humus) and living organisms
- C horizon: subsoil - denser than A horizon, higher mineral content, lower fertility
R horizon: solid rock that has not been broken down
122
Which horizon levels does desertification degrade?
- degrades O and A horizon
123
Describe soil texture
- particle size of the different soils that we have
- eg; clay has much smaller particles than sand
- mixing different particle sizes = different soil texture
124
What creates different soil textures?
- mixing different particle sizes
125
What is the order of particle size?
- (largest) gravel - sand - silt - clay - colloids (smallest)
126
What is porosity?
- the total volume of pore space in a given volume of soil
- determines the amount of water that can be absorbed by soil when saturated
127
What is permeability?
- the ease with which water can filter into the pore spaces and can be withdrawn from them
- small particles = low permeability : high SA : small individual pores
- low permeability: more soil flooded/water logged
- large particles: fewer big pores, smaller particles: many small pores - clay has a higher porosity than sand
128
- what is soil water?
- soil serves as a reservoir for the moisture plants require
129
What is the available water capacity?
- a measure of the water available to plants
- commonly known as the difference between the amount of water at field capacity and the amount of water at wilting point
- this is the water a plant has a chance of using
130
What characteristic of soil is important for water capacity?
- soil texture influences the available water capacity of soil
131
Why is texture important for soil retention?
-soil colloids are very tiny mineral or organic particles
- important for nutrient retention in soil
- eg clay has a much higher water capacity than sand
132
How/why do nutrients 'stick' to soil?
-type of clay particle are negatively charged surrounded by layer of positively charged ions (important minerals necessary for plant growth)
- plant nutrients can move from the adsorption sites on the colloid into the soil water solution where they are available for root uptake
133
What is population momentum?
- age structure diagram shows a lot of young people - will have many children population will grow
134
what is replacement fertility?
replacement fertility is the goal: when births are equal to deaths, zero population growth, and we exactly replace the size of the population form one generation to the next
135
Can a native species be invasive?
NO! A native species cannot be invading its own habitat - but otters are not invasive but irresponsibly managed
136
What is the environmental DNA program used for carp detection?
- this is an early detection method to determine whether carp have entered the great lakes
137
Would climate change be an effective deterrent against asian carp?
nope - highly adaptable and metabolic processes happen faster in warmer water = quicker development and can avoid predation due to size sooner
--> increased metabolism and development, decreased age of maturity leading to earlier reproduction, and increased population growth rates.
138
what is the principle cause of deforestation in Canada?
agriculture
139
How does mercury enter the food chain?
- elemental (gaseous) mercury gets onto land and water --> bacteria converts into methyl mercury --> gets absorbed by phytoplankton --> eaten by zooplankton --> small fish --> large fish
(enters food chain as its adsorbed onto the phytoplankton - described as entering the food chain once it becomes methyl mercury - because methyl mercury is bioavailable we define it entering the food chain when it is in that form)
140
What are some of the side effects of water erosion?
- clogs gills, increases turbidity (preventing photosynthesis and certain fish cannot hunt)
141
Are non point source pollutants all anthropogenic?
They can be natural or human made - bank erosion or and run off from pesticides are both harmful
- anything that degrades quality of the water
142
What is strip harvesting?
- harvesting trees in thinner, longer areas to mimic the natural disturbances that occur in a forest
143
How much of the global forests have been lost in the last 3 centuries?
- 25% of the earth was covered in forest, in the last 300 years 35% of forests have been lost
144
which form of deforestation is preferred in Canadian boreal forests?
strip harvesting
145
When might clear cutting be a viable option in harvesting?
- if it benefits the health of the forest overall: removes invasive, unhealthy, or genetically inferior trees and replaces them with healthy stock
146
What does available water capacity mean? What determines it?
- available water capacity refers to the amount of water that can be held in soil that is available to plants
- this means that soil texture, and its ability to retain and hold water, can alter the available water capacity
147
What is deposition?
The process by which eroded materials are moved and placed in a new area - organic matter incorporates into substrate mixing with materials
148
Does clay or sand have a higher available water capacity?
Clay has a higher available water capacity due to its high surface area - low permeability and high porosity means that it can hold water well
Sand has a high permeability and low posterity which means water flows easily through it, does not retain as well.
149
What makes up soil?
Air, water, nutrients, living organisms, humus, roots
150
Which forms of weathering does climate change the rate?
- physical and chemical weathering: both can change rate depending on climate
151
Describe nutrient leaching
- in acidic soils H+ are higher in concentration, which can replace the ability / presence of helpful nutrient cations like mg+, ca+, and k +
152
What soil pH is nutrient leaching likely to occur?
Acidic soils!
153
What are some major events act have occurred in agriculture in the past century?
- pesticides, fertilizers, mechanical technology (fossil fuels and tractors), high yield varieties, monocultures
154
What is the green revolution?
- a coordinate group effort to eliminate hunger by providing underdeveloped nations in Asia modern agricutlrual technology
155
What aspect of industrial agriculture was implanted in the green revolution?
- intensification: increasing the yield through all of the methods
- fed down to many developing countries to reduce starvation
- results have affected soil interiority and bidoviesuty In aquatic and terrestrial ecosystems
156
What was the initial response to the green revolution? What are the effects now?
- decreased a lot of hunger
- over time crop yields increased exponentially
- the green revolution increased agricultural productivity!
- now those efforts are leading to deflation of soil and decreased biodiversity in terrestrial and aquatic environments
157
What are high yield varieties?
- crops that have a higher yield than average - allowed for the green revolution to be so productive
- rice, wheat, corn
- produce through our understanding of evolution and improved science
158
What are the requirements for high yield varieties?
- large amounts of fertilizers, pesticides, and irrigation
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What is selective breeding?
- similar to natural selection except humans act as the selective pressure
- not based on fitness but chosen traits
- we choose desirable traits (higher yield, larger size, drought resistance) and breed those plants (move pollen form one plant to the other)
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What are monocultures?
- a large expanse of a single crop
- increases output and efficiency
- devastating for biodiversity
- highly vulnerable to pests and disease
- leads to nutrient depletion of the soil
- humans become dependant (90% of food is based on 15 crops and 8 domestic species)
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Where does the majority of food come from?
- 90% of our food comes from 15 crops and 8 livestock species
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What are the two forms of fertilizers?
- inorganic and organic
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Describe inorganic fertilizers?
- industrially mined or synthetically manufactured nutrient supplements (typically a mix of Na, P, K)
- inorganic fertilizers are responsible for the massive increase of food production (provide extra nutrients to plant to grow better)
- Haber-bosch process: process where nitrogen fixed by hydrogen from natural gas produces ammonia-
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Describe organic fertilizers?
- initiated by living things: compost, crop residue, vegetation, manure
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What are the consequences of fertilizer?
pollutes groundwater, eutrophication of freshwater and marine water sources, air pollution, nitrogen oxides (fertilizers responsible for 1/2 N in flux)
- fertilizers can also decrease nutrients available or other plants thereby degrading the soil and causing dependant on fertilizers
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What is irrigation? What are its consequences if done irresponsibly?
- irrigation is when crops are watered
- over 70% of the water removed from aquifers and water sources is used for irrigation
- poor irrigation practices lead to : soil salinization, depletion of groundwater, surface subsistence due to depletion of aquifers, depletion pollution and salivation of surface water
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What is soil salinization?
- salinization and warerlogging of soil out adequate drainage can decrease crop yields
- 20% of all irrigated land from California to ausirlai have been impacted by accumulation of salt
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Is salinization easier to prevent or manage?
- salinization is easy to prevent than mitigate
- increase drainage, plant salt resistant plants, grow crops that need less water, plant trees that take up water faster than crops, irrigate more efficiently
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What are pesticides?
Monocultures are highly vulnerable to pests so require pest citron with the use of chemical pesitices
- boost crop production and reduce blemishes and labour costs
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What are some concerns associated with pesticide use?
- pest resistance is a large concern with pesticide use - bugs can adapt - must continuously use stronger and stronger pesticides
- pesticides leave toxic residue on plants, harmful to farmers and harm soil biodiversity, and enter groundwater
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What is pollination in Canada worth at a monetary value?
2.1 billion dollars
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How much of the world's crops do animals pollinate?
3/4 of the worlds crops
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What are some threats to pollinators?
- threatened by habitat loss, pesticide use and climate change
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What are the advantages and disadvantages of fertilizer use?
- beneficial: can increase yield and grow crops where unable to before
- negative: can lead to eutrophication and deplete soil leading to dependency on fertilizers
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What is the second green revolution called?
Green revolution 2.0 : the GENE revolution
- involves genetic modification
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What are the 3 forms of GMO?
-transgenic - DNA from different species added
- cisgenic: DNA from same or similar species added
- intragenic: no new DNA, either removed or added
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What is CRISPR?
a form of gene editing
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What are the 4 kinds of GMO ?
- BT - has a gene that creates a toxin that can kill some pests
- HT - herbicide tolerant
- nutritionally enhance food: plants which produce more of a nutrient or produce a nutrient it doesn;t nroamlyl produce
- GM animals: Salmon that grow to bigger sizes, pigs that produce more omega 3 fatty acids
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What food is GMO free?
- only certified food is GMO free!
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Describe Africa's role in the green revolution
- africa was left behind In both revolutons
lack food self sufficiency and food sovierignity
- for any regions food security may hinge on attaining food sovereignty - putting control of the food supply in the hands of the region and its farmers
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What may be the solution to food insecurity in regions of Africa?
- allowing food sovereignty
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What is limiting the use of GMOs?
→ Currently the number of countries growing GM crops is limited and the number of companies producing GM seeds is even fewer and mostly large multinational companies which puts patents on their seeds
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Are GMOs harmful?
GMOs are not considered to be harmful to animals or people, no evidence
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