Ch 53: Ecosystems and Global Ecology

Question 1

ecosystem

Answer 1

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

Question 2

Primary producer/autotroph

Answer 2

organism that can synthesize its own food from inorganic sources

Question 3

gross primary productivity (GPP)

Answer 3

The total energy captured by autotrophs

Question 4

GPP is used in 2 ways:

Answer 4

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

Question 5

Why do plants capture such little energy?

Answer 5

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

Question 6

How energy/nutrients flows?

Answer 6

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

Question 7

EX: Balsam fir Food Web

Answer 7

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

Question 8

How much energy transferred to next trophic level?

Answer 8

10%

Question 9

NPP varies…

Answer 9

• 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

Question 10

Human currently prevent/appropriate 24% of potential NPP

What is it divided into?

Answer 10

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

Question 11

Biogeochemical cycle

Answer 11

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

Question 12

Impact of detritus on nutrient cycle

Answer 12

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

Question 13

Rate of nutrient cycling depends on three factors

Answer 13

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

Question 14

What is minimal in tropical wet forests?

Answer 14

• 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

Question 15

EX: Bromeliads

Answer 15

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

Question 16

How are nutrients exported?

Answer 16

• Cellular respiration

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

Question 17

What speeds up nutrient export?

Answer 17

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

Question 18

4 major mechanisms to replace lost nutrients:

Answer 18

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

Question 19

aquifers

Answer 19

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

Question 20

closed aquifers

Answer 20

are contained

-nonporous rock layers above

Question 21

open aquifers

Answer 21

can be recharged by percolation from above

Question 22

Human impact on water cycle

Answer 22

• Groundwater depletion (extraction, sealing soil surface)

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

Question 23

Nitrogen cycle reservoirs

Answer 23

• atmospheric nitrogen
• terrestrial organisms
• aquatic organisms

Question 24

Consequences of removing trees for nitrogen cycle

Answer 24

lose in nitrogen due to lose in storing capacity

Question 25

Human activities deeply alter N cycle by:

Answer 25

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

Question 26

Adding excess nitrogen can be harmful-How?

Answer 26

–Reduces biodiversity | –Increases pollution (aquatic systems)

Question 27

Main reservoir of phosphorus

Answer 27

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

Question 28

What has increased the amount of phosphorus?

Answer 28

Mining and fertilizing | -often causing eutrophication

Question 29

Carbon cycle main reservoirs

Answer 29

- small percentage atmospheric - mainly aquatic organisms, chemical processes in ocean - terrestrial organisms, soil,litter - fossil fuels

Question 30

Global warming

Answer 30

increase in the average temperature of the planet

Question 31

Global climate change

Answer 31

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

Question 32

Where is average temp increasing more so?

Answer 32

–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

Question 33

Positive feedback

Answer 33

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

Question 34

Negative feedback

Answer 34

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

Question 35

Geographic Range Shift

Answer 35

- 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

Question 36

Phenology Shift

Answer 36

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

Question 37

EX of Phenology Shift

Answer 37

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

Question 38

Evolutionary Adaptation

Answer 38

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

Question 39

Increase in Ocean Acidification

Answer 39

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)

Question 40

NPP decreasing (land)

Answer 40

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

Question 41

NPP decreasing (ocean)

Answer 41

- 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