L12 Flashcards
Four ways carbon dioxide exchanged between the atmosphere and terrestrial ecosystems?
Photosynthesis
Plant respiration
Soil respiration
Disturbance
Net sinks/ source refers to:
- Greater in than out / greater out than in
- There is still movement both ways
Drought events weaken what?
Tropical carbon sinks
Carbon source examples
Deforestation, as supported by Le Quere et al
Terrestrial carbon sink is …
Growing over time Le Quere et al but varies year upon year
What causes terrestrial ecosystems to act as carbon sinks?
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
4 causes of terrestrial ecosystems to act as carbon sinks?
Demography
Physiology
Phenology
Migration
Demography
- Younger, regenerating forests are in the mid latitudes
- Old growth forests are in the tropics and high latitudes
Pugh et al
Tropical forests account for … of carbon stored in vegetation and … of photosynthesis on land
1/2
1/3
Tropical forests make important contributions to:
Sink activity and deforestation
Research shows the amazon is a weakening…?
Carbon sink - Brienen et al
African forests are persistent …?
Carbon sinks - Hubau et al
Forest carbon gains are related to …
rising CO2 and climate change Hubau et al
Rising CO2 leads to greater photosynthesis, leading to an enhanced carbon sink this accounts for … of CO2 emissions?
30%
what does CO2 fertilisation depend on?
Soil nutrients and mycorrhizas
What increases the mortality of amazon trees?
High temperatures, drought, el nino and low wood density
What predicts species that are most at risk?
Plant traits,
species that grow fast, are small in size and have low wood density
Which processes control carbon sinks in mature tropical forests?
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.
