L12

Question 1

Four ways carbon dioxide exchanged between the atmosphere and terrestrial ecosystems?

Answer 1

Photosynthesis

Plant respiration

Soil respiration

Disturbance

Question 2

Net sinks/ source refers to:

Answer 2

• Greater in than out / greater out than in
• There is still movement both ways

Question 3

Drought events weaken what?

Answer 3

Tropical carbon sinks

Question 4

Carbon source examples

Answer 4

Deforestation, as supported by Le Quere et al

Question 5

Terrestrial carbon sink is …

Answer 5

Growing over time Le Quere et al but varies year upon year

Question 6

What causes terrestrial ecosystems to act as carbon sinks?

Answer 6

Fix more C in photosynthesis than they release in respiration

store C in stocks with slow turnovers rates eg wood / soil which have long residence times

Question 7

4 causes of terrestrial ecosystems to act as carbon sinks?

Answer 7

Demography
Physiology
Phenology
Migration

Question 8

Demography

Answer 8

• Younger, regenerating forests are in the mid latitudes
• Old growth forests are in the tropics and high latitudes

Pugh et al

Question 9

Tropical forests account for … of carbon stored in vegetation and … of photosynthesis on land

Answer 9

1/2

1/3

Question 10

Tropical forests make important contributions to:

Answer 10

Sink activity and deforestation

Question 11

Research shows the amazon is a weakening…?

Answer 11

Carbon sink - Brienen et al

Question 12

African forests are persistent …?

Answer 12

Carbon sinks - Hubau et al

Question 13

Forest carbon gains are related to …

Answer 13

rising CO2 and climate change Hubau et al

Question 14

Rising CO2 leads to greater photosynthesis, leading to an enhanced carbon sink this accounts for … of CO2 emissions?

Answer 14

30%

Question 15

what does CO2 fertilisation depend on?

Answer 15

Soil nutrients and mycorrhizas

Question 16

What increases the mortality of amazon trees?

Answer 16

High temperatures, drought, el nino and low wood density

Question 17

What predicts species that are most at risk?

Answer 17

Plant traits,

species that grow fast, are small in size and have low wood density

Question 18

Which processes control carbon sinks in mature tropical forests?

Answer 18

Rising CO2 boosts photosynthesis and wood production if sufficient soil nutrients are available.

Rising temperatures and drought limit wood production, and may be causing a saturation of the carbon sink in Amazonia.

Regional droughts linked to climate oscillations (El Niño) are increasing tree mortality in Amazonia. Plant traits predict vulnerability of particular species.

African forests are at higher altitude and less impacted by heatwaves and droughts.