lec 18- ecosystems

Question 1

what is the definition of an ecosystem?

Answer 1

A spatially explicit unit of the earth that includes all of the organisms, along with all components of the abiotic environment within its boundaries

Question 2

what is ecosystem ecology?

Answer 2

the study of natural systems from the standpoint of the flow of energy and the cycling of matter

Question 3

what are the biological processes in an ecosystem?

Answer 3

-primary production
-decomposition
-species interactions
-populations growing/shrinking

Question 4

what do the biological processes influence in ecosystems?

Answer 4

the movement of energy and nutrients

Question 5

what is an example of the movement of material from the water to terrestrial environments?

Answer 5

aquatic invertebrae hatching from eggs and turning into larvae, which then eventually grow wings and go to the land where they are consumed by birds and other predators

Question 6

how do humans fit into ecosystems?

Answer 6

can intercept fish when fishing and taking nutrients from ecosystems

Question 7

what two things place constraints on ecosystems?

Answer 7

energy conservation and mass conservation

Question 8

how are ecosystems studied?

Answer 8

-by the mass balance approach: estimate the flow of material and energy into the box and then separately the flow of material outside of the box, material in the box is storage

inputs = outputs + storage

Question 9

what is the highest level of primary production called?

Answer 9

gross primary production (GPP)

Question 10

what is GPP?

Answer 10

the rate at which energy is captured and assimilated in an area, all the energy captured from photosynthesis

Question 11

how much of GPP during photosyntesis is lost to respiration and kept for growth/reproduction?

Answer 11

respiration = 60%
growth = 40%

Question 12

what is net primary production (NPP)?

Answer 12

rate at which energy is assimilated/absorbed and converted into producer biomass in an area, the energy remaining after plants use some for respiration

Question 13

what is ecological efficiency?

Answer 13

% of NPP moving from one trophic level to the next, usually small amounts go from one to another due to a lot of primary production being lost

Question 14

what is assimilation efficiency?

Answer 14

how much % of energy is digested and absorbed compared to the amount ingested

Question 15

what does assimilation efficiency depend on?

Answer 15

the quality of the diet (e.g. herbivore assimilation efficiency depends on quality of plant matter)

Question 16

what is production efficiency and the two types?

Answer 16

the % of energy ingested that is used for growth (GPE, gross production efficiency)

the % of energy assimilated that is used for growth (NPE, net production efficiency)

Question 17

why do carnivores require 10 times more the energy needed than vegetarians?

Answer 17

due to carnivores being higher on the food web which has less biomass and energy, so eating lower organisms in the food chain gives more energy

Question 18

why are some aquatic biomass pyramids upside down?

Answer 18

because the primary producers are small and can be consumed and controlled very well, while their consumers are larger in size and last longer than them

Question 19

when can the production/biomass (P/B) ratios be high?

Answer 19

-high for small organisms
-high turnover/ small generation times, easier to replace themselves quicker

Question 20

where does npp that is not consumed or absorbed go to?

Answer 20

detrital pool of carbon

Question 21

what does detritus accumulation depend on?

Answer 21

-water, temperature, and oxygen

-detritus breaks down in warmer areas like the tropics (1-2 years) compared to cold like temperate (4-16 years)

Question 22

what is autochthonous production?

Answer 22

producing energy in the ecosystem (e.g. plants phytoplankton)

Question 23

what is allochthonous production?

Answer 23

producing energy outside the ecosystem (e.g. leaf litter fall)

Question 24

what is the river continuum concept?

Answer 24

small streams = low light, low primary production
big rivers = more light, high primary production

Question 25

what reaction is needed to transform energy in ecosystems?

Answer 25

redox reactions in plants to make carbon, photosynthesis reduces C to store energy, and respiration oxidizes C to power cells

Question 26

what does the oceans effects on carbon help us do?

Answer 26

helps us estimate past atmospheric CO2 concentrations, carbon dating