Ch 53: Ecosystems and Global Ecology Flashcards

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1
Q

ecosystem

A

one or more communities in an area & abiotic components (e.g., soil, climate, water, and atmosphere)
These components are tied together by flows of energy and nutrients

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2
Q

Primary producer/autotroph

A

organism that can synthesize its own food from inorganic sources

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3
Q

gross primary productivity (GPP)

A

The total energy captured by autotrophs

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4
Q

GPP is used in 2 ways:

A

1.to stay alive through cellular respiration
2.growth and reproduction.
In primary producers, this energy is called net primary productivity (NPP)

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5
Q

Why do plants capture such little energy?

A

–Fraction of the wave length spectrum
–Less or 0 during winter
–Stalled if too dry (stomata close)
–Enzyme efficiency varies with temp

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6
Q

How energy/nutrients flows?

A
  • energy dissipates as it flows through ecosystems and released by heat
  • nutrients constantly cycling through ecosystems
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7
Q

EX: Balsam fir Food Web

A

Trophic levels

  1. The first trophic level is the balsam fir.
  2. Six insect herbivores feed on the tree.
  3. Sixty-six species of parasitoids and 21 species of pathogens feed on these insect herbivores
  4. Twenty-three secondary parasitoids and a fungus
  5. Six tertiary parasitoids
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8
Q

How much energy transferred to next trophic level?

A

10%

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9
Q

NPP varies…

A
  • NPP greater by equator
  • desert -no to low NPP
  • Marine Enviro: coral reefs most productive -shallow waters and near continent (high nutrients)
  • Land Enviro: tropical wet forest most productive
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10
Q

Human currently prevent/appropriate 24% of potential NPP

What is it divided into?

A

53%-directly harvested/used
40%-prevented thru land-use change (ex: parking lots)
7%-burned by human-induced fires

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11
Q

Biogeochemical cycle

A

path that an element takes as it moves from abiotic systems through organisms and back again

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12
Q

Impact of detritus on nutrient cycle

A

decomposition of detritus may limit how fast nutrients move through an ecosystem

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13
Q

Rate of nutrient cycling depends on three factors

A
  1. Abiotic conditions such as oxygen availability, temperature, and precipitation
  2. The quality of the detritus as a nutrient source for the fungi, bacteria, and archaea that accomplish decomposition
  3. The abundance and diversity of detritivores present
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14
Q

What is minimal in tropical wet forests?

A
  • uppermost layer of soil
  • It is warm all year long, therefore decomposition is high
  • Bacteria and archaea ensure that decomposition keeps pace with inputs
  • Cycling in cooler climates is much slowe
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15
Q

EX: Bromeliads

A

Bromeliads - no soil, leaves specialized to take up nutrients from decaying plant material that falls into their leaf wells.
•Each plant and each leaf well is a miniature ecosystem, with nutrients and energy transferred within a food web of up to 60 species of aquatic insects and insect larvae

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16
Q

How are nutrients exported?

A
  • Cellular respiration

- If a detritivore or an herbivore eats a plant and moves out, the nutrients are exported

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17
Q

What speeds up nutrient export?

A
  • Farming, logging, burning, and soil erosion, accelerate nutrient export
  • For an ecosystem to function normally, lost nutrients must be replaced
18
Q

4 major mechanisms to replace lost nutrients:

A
  1. Ions that act as nutrients are released as rocks weather
  2. Nutrients blow in on soil particles or arrive as solutes in streams
  3. Carbon is added when primary producers fix carbon
  4. Nitrogen is added when nitrogen-fixing bacteria convert molecular nitrogen (N2) in the atmosphere to usable nitrogen in ammonium or nitrate ions
19
Q

aquifers

A

layers of porous rock, sand, or gravel that are saturated with water
-store groundwater

20
Q

closed aquifers

A

are contained

-nonporous rock layers above

21
Q

open aquifers

A

can be recharged by percolation from above

22
Q

Human impact on water cycle

A
  • Groundwater depletion (extraction, sealing soil surface)

- Converting forest to agriculture – lowers water holding capacity – water drains faster

23
Q

Nitrogen cycle reservoirs

A
  • atmospheric nitrogen
  • terrestrial organisms
  • aquatic organisms
24
Q

Consequences of removing trees for nitrogen cycle

A

lose in nitrogen due to lose in storing capacity

25
Q

Human activities deeply alter N cycle by:

A

–Cultivation of crops that harbor nitrogen-fixing bacteria
–Industrially produced fertilizers
–The burning of fossil fuels, which releases nitric oxide

26
Q

Adding excess nitrogen can be harmful-How?

A

–Reduces biodiversity

–Increases pollution (aquatic systems)

27
Q

Main reservoir of phosphorus

A

Earth’s crust, where it is slowly mobilized by weathering of rocks

28
Q

What has increased the amount of phosphorus?

A

Mining and fertilizing

-often causing eutrophication

29
Q

Carbon cycle main reservoirs

A
  • small percentage atmospheric
  • mainly aquatic organisms, chemical processes in ocean
  • terrestrial organisms, soil,litter
  • fossil fuels
30
Q

Global warming

A

increase in the average temperature of the planet

31
Q

Global climate change

A

sum of all the changes in local temperature and precipitation patterns caused by global warming

32
Q

Where is average temp increasing more so?

A

–Average temperature in polar regions will increase more than in the tropics
–Some ecosystems at the same latitudes will experience higher temperature increases than others due to wind patterns, ocean currents, and other factors
–The average temperature in some seasons will change more than in others

33
Q

Positive feedback

A

occurs when changes due to global warming result in further acceleration of warming
ex: A warmer and drier climate has increased the frequency of forest fires, which release CO2, leading to more warming

34
Q

Negative feedback

A

occurs when changes due to global warming result in increased uptake and sequestration of CO2 and other greenhouse gases
-should reduce global warming

35
Q

Geographic Range Shift

A
  • species may move toward the poles, toward higher altitudes, or toward areas of adequate precipitation
  • lead to changes in species interactions and mismatches between species and resources
36
Q

Phenology Shift

A
  • timing of seasonal events (phenology) is changing in many biomes
  • As seasonal cues shift, organisms also shift their biological activities to match
37
Q

EX of Phenology Shift

A

snowshoe hares use daylight length as a cue to change their coat colour from white to brown in the spring. As the snow melts earlier, the hares are not camouflaged and are subject to increasing predation by lynx

38
Q

Evolutionary Adaptation

A

changing climate and species interactions are causing allele frequency to change

ex: tawny owl (Strix aluco) ranges from pale gray to brown. In winter, the pale gray birds are less conspicuous and have higher survivorship
- As the climate has warmed and the snow has melted earlier, brown owls are less selected against, and the frequency of brown owls has increased

39
Q

Increase in Ocean Acidification

A

When CO2 dissolves in water, it forms carbonic acid. Increased levels of CO2 increase the rate of this reaction

  • water becomes too acidic
  • affects larvae, fish
  • reduces the availability of calcium carbonate ions (coral)
40
Q

NPP decreasing (land)

A

Increases in CO2 would be expected to lead to increased photosynthesis, but widespread drought has decreased NPP over vast areas

41
Q

NPP decreasing (ocean)

A
  • Drop in marine productivity due to changes in water density: Water reaches its highest density at 4ºC, and this leads to stratification
  • However, when the temperature of surface water rises due to global warming, this water becomes even less dense than benthic water
  • prevents water currents from carrying nutrients from the benthic zone to the surface