ecosystem Ecology

Question 1

What do scavengers, detritivores, and decomposers have in common?

Answer 1

They all feed on dead material.

Question 2

What distinguishes scavengers from detritivores?

Answer 2

Scavengers eat recently dead animals, while detritivores eat decomposing organic matter.

Question 3

What is the role of decomposers in the ecosystem?

Answer 3

Decomposers break down dead matter to basic elements.

Question 4

What is the focus of population ecology?

Answer 4

It focuses on organisms, their interactions, and growth.

Question 5

What does ecosystem ecology focus on?

Answer 5

It focuses on energy and material flows.

Question 6

Define a ‘pool’ in ecosystem ecology.

Answer 6

A pool is the storage of material, measured in amount.

Question 7

Define a ‘flux’ in ecosystem ecology.

Answer 7

A flux is the movement between pools, measured in rates.

Question 8

What is a steady state in ecosystem ecology?

Answer 8

Input equals output in an open system, so the pool remains stable over time.

Question 9

Define residence time.

Answer 9

Residence Time = Pool size / flow-through rate.

Question 10

Define turnover rate.

Answer 10

Turnover Rate = Flow-through rate / pool size.

Question 11

Give an example of a carbon pool with a fast turnover rate.

Answer 11

Atmosphere.

Question 12

Give an example of a carbon pool with a slow turnover rate.

Answer 12

Soils.

Question 13

Define Net Primary Production.

Answer 13

Biomass available for consumption by animals and microbes.

Question 14

Define Net Ecosystem Exchange.

Question 15

Define carbon sequestration.

Answer 15

The removal of CO2 from the atmosphere and long-term storage in the biosphere or ocean.

Question 16

What flux feeds all heterotrophic life in the carbon cycle?

Answer 16

Carbon flow from producers (plants) to consumers (herbivores/carnivores).

Question 17

What are the two main drivers of global terrestrial NPP?

Answer 17

• Temperature (longer growing season) * Precipitation

Question 18

What happens to NPP with too much rain?

Answer 18

Too much rain → clouds → less sunlight → lower NPP.

Question 19

What are additional factors for primary productivity at the local level?

Answer 19

• Soil fertility * Leaf area index (LAI) * Species composition

Question 20

What terrestrial biomes have some of the highest NPP?

Answer 20

Tropical forests due to high sunlight, warmth, and rainfall.

Question 21

Which biome contributes the most to total global productivity?

Answer 21

Oceans contribute ~50% of global NPP due to size.

Question 22

Where is oceanic NPP maximized?

Question 23

When do ecosystems take up CO2 and when do they release CO2 on a daily basis?

Answer 23

Daily: Photosynthesis during the day = CO₂ uptake; Respiration at night = CO₂ release.

Question 24

When do ecosystems take up CO2 and when do they release CO2 on a seasonal basis?

Answer 24

Seasonal: CO₂ uptake in growing season (spring/summer); CO₂ release in fall/winter.

Question 25

Why does atmospheric CO2 fluctuate annually?

Answer 25

Seasonal cycles: Peaks in spring (less plant uptake), dips in fall (after growing season).

Question 26

What has caused atmospheric CO2 to increase?

Answer 26

Human activity—agriculture (8,000 years ago) and fossil fuels (~1880s onward).

Question 27

What were the pre-industrial values of atmospheric CO2?

Answer 27

~180–300 ppm.

Question 28

What is the current level of atmospheric CO2?

Answer 28

~428 ppm.

Question 29

Fill in the blank: Only __% of the annual human-caused CO2 emission ends up in the atmosphere.

Answer 29

50% stays in the atmosphere.

Question 30

Fill in the blank: Of the remaining amount, ___% is sequestered in the ocean and ___% on land.

Answer 30

* 25% in ocean * 25% on land

Question 31

What are the three pumps or transport systems that sequester carbon in the deep ocean?

Answer 31

* Physical pump * Organic carbon pump * Calcium carbonate pump

Question 32

What are the components of the water balance equation?

Answer 32

P = ET + R + D + ΔS.

Question 33

What do the components in the water balance equation represent?

Answer 33

* P: Precipitation * ET: Evapotranspiration * R: Runoff * D: Deep drainage * ΔS: Change in water storage

Question 34

What are the components of the energy balance equation?

Answer 34

Rnet = H + LE + G.

Question 35

What do the components in the energy balance equation represent?

Answer 35

* Rnet: Net radiation (incoming – outgoing) * H: Sensible heat flux (to atmosphere) * LE: Latent heat flux (from evaporation/condensation) * G: Ground heat flux

Question 36

What flux appears in both the water and energy balance equations under different names?

Answer 36

Evapotranspiration (ET) in the water cycle = Latent Heat (LE) in the energy cycle.

Question 37

How is precipitation defined?

Answer 37

Water falling from the atmosphere (rain, snow, hail).

Question 38

Define runoff.

Answer 38

Water moving above ground laterally.

Question 39

Define subsurface flow.

Answer 39

Water moving laterally below ground.

Question 40

Define infiltration.

Answer 40

Water entering soil, increasing soil moisture.

Question 41

Define deep drainage.

Answer 41

Water percolating deep into the ground (recharge groundwater).

Question 42

Define transpiration.

Answer 42

Water vapor lost from plant leaves via stomata.

Question 43

Define evaporation.

Answer 43

Liquid water → vapor from surfaces.

Question 44

Define evapotranspiration.

Answer 44

Evaporation + transpiration.

Question 45

What is potential evapotranspiration?

Answer 45

PET: Max ET if water is unlimited.

Question 46

How does humidity affect PET?

Answer 46

Humidity ↑ = PET ↓.

Question 47

How does wind speed affect PET?

Answer 47

Wind speed ↑ = PET ↑.

Question 48

How does surface roughness affect PET?

Answer 48

Surface roughness ↑ = turbulence ↑ = PET ↑.

Question 49

What does it indicate if ET << PET?

Answer 49

Very arid or water-limited conditions.

Question 50

What percentage of Earth’s water is freshwater?

Answer 50

1%.

Question 51

What percentage of Earth’s freshwater is in rivers and lakes?

Answer 51

>1%.

Question 52

What percentage of Earth’s freshwater is in ice?

Answer 52

2%.

Question 53

Define ‘watershed’.

Answer 53

Area draining water to a common outlet (e.g., river, reservoir).

Question 54

What is the biggest watershed in North America?

Answer 54

Mississippi River Basin to Gulf of Mexico.

Question 55

Define albedo.

Answer 55

% of reflected shortwave radiation.

Question 56

How does albedo affect Earth's climate?

Answer 56

* Higher albedo = more reflection = cooling effect * Lower albedo = more absorption = warming effect

Question 57

Give examples of land cover with high and low albedo.

Answer 57

* High albedo: Ice, cropland * Low albedo: Water, forest

Question 58

What type of radiation does the Sun emit?

Answer 58

Shortwave radiation.

Question 59

What type of radiation does the Earth emit?

Answer 59

Longwave radiation.

Question 60

What is meant by radiation?

Answer 60

Energy transfer via electromagnetic waves (e.g., sunlight, heat).

Question 61

Explain the greenhouse effect.

Answer 61

Longwave radiation is absorbed by greenhouse gases (GHGs) → heats atmosphere → increases downward longwave radiation.

Question 62

Are there planets that do not have a greenhouse effect?

Question 63

Name three greenhouse gases.

Answer 63

* CO₂ * CH₄ * N₂O

Question 64

What processes release CO₂?

Answer 64

* Fossil fuels * Land use * Cement

Question 65

What processes release CH₄?

Answer 65

* Fossil fuels * Livestock * Rice * Permafrost

Question 66

What processes release N₂O?

Answer 66

Fertilizers.

Question 67

How much warmer has the average Earth temperature been in the last 3 years compared to the 1960s?

Answer 67

Global average temperatures are 1.1-1.3°C warmer than the 1960s.