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Food and Forest > Part II > Flashcards

Part II Flashcards

1
Q

why is it difficult to estimate current rate of extinction?

A
  • difficult to say w/ certainty that a species is extinct
  • most species unknown to scientists, therefore extinct species also unknown
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2
Q

cycles that generate climate changes short term

A
  • earth revolves on its axis leading to alternating cooling and warming w/ solar radiation
  • earth orbits sun, tilted axis generates annual climactic cycles b/w northern hemisphere tilted toward sun during half of the orbit, southern hemisphere tilted toward sun other half
  • LEADS TO
    • diurnal-nocturnal behaviour of animals
    • seasonal growth and death of annual plants
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3
Q

cycles that generate climate changes long term

A
  • variaration of tilt of earth’s axis
  • variation of shape of earth’s orbit around sun
  • procession of equinoxes: distance form earth to sun cna either accentuate or ameliorite effects of axial tilt on weather
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4
Q

3 concerning observations re:global warming

A
  • greenhouse gases lead greenhouse effect
  • increased concentration of gg lead to increase greenhouse effect
  • mean global temperature has increased
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5
Q

greenhouse gases

A

water vapor, carbon dioxide, methane, etc.

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6
Q

greenhouse effect

A

gg allow solar radiation to penetrate atmosphere and warm earth’s surface and inhibit reradiation of energy back to space

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7
Q

causes of global warming

A
  • increased consumption of fossil fuels
  • devasation of ecosystems (release gg)
  • astronomical factors, increased photosynthesis (unpopular)
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8
Q

will organisms be able to adapt to future climate change?

A
  • have been able to adapt well in past but maybe not in future
    • current pops. already stressed by habitat degradation and overexploitation
    • stressed pops. are small and therefore have lower chance to produce offspring
    • human alteration of landscapes has reduced quantity of suitable habitats and fragmented landscapes by roads, etc. decreasing odds of individuals arriving in new suitable habitat
  • possible temps will rise to unprecedented levels
  • melting ice caps reduce shoreline
  • unprecedented rate of increase in temp
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9
Q

why are rare species more vulnerable to extinction than common species?

A
  • greater chance of pushed to extinction by environmental change
    • environmental event may encompass species’ entire range
  • demographic problems
    • unbalanced sex ratio can limit birth rate
    • more likely to happen to small pops.
  • genetic problems
    • inbreeding
    • genetic drift
    • bottlenecks
    • restricted ability to adapt
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10
Q

why are some species particularly sensitive to human-induced threats?

A
  • limited adaptability and resilience
    • may be due to low reproductive capacity, limited dispersal capabilities, inflexible habitat requirements, etc.
  • human attention
    • may be edible, extremely unpopular (e.g. bats)
  • ecological overlap
    • tied to human-preferred ecosystems (e.g. w/ fertile soil and benign climates)
  • large home-range requirements
    • cannot fit in among humans
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11
Q

population

A

groups of individuals of some species occupying a defined area at same time

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12
Q

meta populations

A

group of diff. patch pops.

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13
Q

turnover

A

subpopulations appearing and disappearing due to colonization and local extinction

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14
Q

population visibility analysis (PVA)

A

any systematic attempt to understand processes that make pop. vulnerable to extinction, technique used to measure minimum viable population

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15
Q

4 interacting factors that might contribute to pop’s extinction

A
  • demographic stochasticity
    • =uncertainty resulting from random variation in reproductive success and survivorship at individual level
  • environmental stochasiticity
    • =random variations in components of habitat quality
    • e.g. climate, nutrients, water
  • catastrophes
    • =dramatic events that occur at random intervals
    • e.g. droughts, hurricanes
  • genetic stochasticity
    • random variation in gene frequencies of a pop. resulting from genetic drift, bottlenecks, inbreeding, etc.
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16
Q

habitat degradation

A

process by which habitat quality for a given species is diminished

17
Q

habitat loss

A

habitat quality so low that environment is no longer usable by given species

18
Q

ecosystem degradation

A

alterations to an ecosystem degrade/destroy habitat for many of the species that constitute the ecosystem

19
Q

ecosystem loss

A

changes to ecosystem so profound to so many species (esp. dominant species) are lost so that ecosystem converted to another type (e.g. deforestation)

20
Q

contamination: air pollution

A
  • extensive research on effects on human and domesticated species, less on wild species
  • destroy plant species downwind from factories
  • eradicate lichen species
  • diminish individuals’ health and ability to reproduce
  • can make aquatic habitats more acidic
21
Q

contamination: water pollution

A
  • aquatic species more vulnerable than land species
  • extinction of species in one place can lead to entire extinction b/c only found in one place
  • less likely to cause extinction if in marine habitats
  • eutrophication and harmful algal blooms
22
Q

contamination: pesticides

A
  • some benign and break down quickly, others wreak havoc (e.g. DDT)
  • biomagnification = pesticides concentrate at top of ecosystem
23
Q

human structures: roads

A
  • curbs/lanes dividers absolute barriers to small, flightless mammals, etc.
  • animals run down even if can cross
  • provide access to habitats to people who want to exploit ecosystem
  • may provide access for exotic species to infiltrate habitat
24
Q

human structures: dams

A
  • limits species’ ability to move up/down stream during mating season
  • e.g. salmon populations eliminated by dams
25
Q

soil erosion

A
  • natural process accelerated by humans (e.g. agriculture)
  • leads to habitat degradation and decreased productivity of land
26
Q

fire regimes

A
  • severe human fires can destroy habitats
  • campaigns to prevent fire also too effective - low intensity fires suppressed, leads to accumulation of fuel
27
Q

water use

A
  • mostly used for agriculture than industry, domestic uses and reservior expansion
  • when remove large quantity of water, biota affected
28
Q

deforestation

A
  • forests grow in places w/ fertile soil so desireable for agriculture
  • slowed, stopped or reversed in some areas
  • demand for forest in developed countries decreased b/c pop stabilised or shift away from agro
  • still issue in tropical regions
  • damages diverse ecosystems
29
Q

desertification

A
  • grasslands/woodlands being degraded until dominated by sparse unproductive veg.
  • usually associated w/ overgrazing and cultivation
30
Q

why do large fragements have more species than small ones?

A
  • greater variety of environments
    • provides niches for additional species
  • likely to have common and uncommon species
    • small fragment likely to only have common species
  • larger samples have more species
31
Q

history of overexploitation

A
  • humans killed off woolly mammoth 11000 years ago
    • overkill (most important factor)
    • climate change
    • disease
    • human-set fires
  • Polynesians arrive in NZ and kill off bird species
    • all types of moas
  • Madagascar extinction
    • giant tortoises
    • giant lemurs (etc.)
  • N.America by colonials
    • nearly eradicated turkeys, beavers
32
Q

what are the two major forms of overexploitation?

A
  • bushmeat
  • overfishing
33
Q

overfishing

A
  • not given enough public scrutiny
    • not sympathetic to fish
    • fishing happens in sea + not w/in national boundaries
    • fish stocks only recently starting to decline
  • fish population phenomena
    • ‘fishing down the food chain’
      • predatory fish that used to dominate catches replaced by species further down food chain
    • individual fisheries collapsing
    • running out of new places to exploit (usually sustain total catch by fishing in remote and deep places)
34
Q

bushmeat exploitation

A
  • wild animal used for human food (esp. in tropical terrestrial ecosystems)
  • profound effects
    • loss of supply of protein
    • exposure to HIV/AIDS and Ebola
  • in W. Africa when have large fish supplies, lower bushmeat levels
    • could be solved if Europeans stopped fishing off their coasts
35
Q

commercial exploitation

A

why does this easily lead to over exploitation?

  • huge potential markets for wild species
  • enormous desire for wealth among exploiters
  • domestic substitutes not identical to wild versions and therefore have lower prices
  • market price of wild species increase as becomes rarer
  • communal resources - costs shared among everyone
  • wildlife found in remote places (lesser legal grip)
  • exploiters have capital to purchase tech to gather wildlife in large quantities
  • disparity in currencies makes selling rare species profitable
36
Q

recreational exploitation

A
  • examples
    • hunters
    • watchers
    • anglers
  • pros/cons
    • bad b/c leads to overexploitation
    • good b/c licenses fund conservation efforts
  • even nonconsumptive exploitation can be harmful to animals b/c shy, etc.
37
Q

incidental exploitation

A
  • e.g. catching tuna w/ nets and drowning dolphins in process
  • most destructive is trawling for shrimp
    • killed turtles but now must have devices on trawlers to release turtles
38
Q

indirect exploitation

A

e.g. roads, fences, etc.

39
Q

consequences of overexploitation

A
  • effects on large species worse b/c larger = more babies
  • tend to hunt animals in reproductive prime or growth prime (i.e. cutting down trees) not at natural mortality
  • tend to kill males more b/c larger and travel more therefore more contact w/people
    • skewed pop can affect reproduction
    • not worst b/c most males mate w/ many females (polygynous)
  • can change genetic structure - kill best and leave worst
  • change landscapes (cut down trees, no longer forest)

Food and Forest (2 decks)

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