Carbon Sources and Sinks Flashcards
Where is the annual feedback of the biosphere on the atmosphere most pronounced?
In Northern latitudes, because it is industrialised and there is more land mass and plants.
Why does the growth rate of CO2 in the atmosphere vary year to year?
Due to ENSO (El Nino Southern Oscillation)
What is a positive ENSO?
El Nino
Can represent droughts, dry conditions.
What is a negative ENSO?
La Nina
Can represent wet conditions.
What is an effect of El Nino?
Droughts impact vegetation of Western Amazonia and SE Asia, leading to carbon losses (due to respiration).
What is the overall relationship between land sinks and deforestation?
What is the relationship in the past 10 years?
Overall: land sink has counteracted deforestation
Last 10 years: deforestation rate has shrunk and land sink is now larger than it.
What makes an ecosystem a carbon sink?
- It fixes more C than it releases each year
- Does this across multiple years
- Stores C with a slow turnover rate
What are tropical forests responsible for?
1/2 of all carbon stored in vegetation
1/3 of all photosynthesis on land
What has long term monitoring of forest carbon stocks across the tropics shown?
Overall net sink
But evidence of it weakening in Amazon (increased mortality, increased turnover of trees)
But evidence of persistent sink in African forests
Why is there greater mortality in Amazon due to droughts than in Africa?
Africa is at a higher elevation so it is cooler.
What does CO2 fertilisation of growth depend on?
Soil nutrients and mycorrhiza
What are the plant traits of a species at risk during drought or storms?
- Fast growers
- Small in size
- Low wood density
How can Amazon trees limit mortality risk?
Drought tolerant species
What is HSM?
Hydraulic safety margin - how close the stem operates in relation to hydraulic failure.
