2.1.8 - changing carbon stores in peatlands over time

What is peat

A thick layer of black or dark brown wet soil material containing high levels of partially composed vegetation

Why can deposition full occur in peat

Because peat is an anaerobic environment due into it being waterlogged but decomposition needs oxygen to occur

What would be the biggest store in a gerschmel diagram

Soil would be the biggest and then biomass and then litter

What is the link between relief, precipitation and areas of peat in the uk

Areas of peat are typically found in highland areas e.g. the Lake District which also has high levels of rainfall which allows for the waterlogged conditions to occur. Due to it being in high altitudes it means that it’s much colder which means that decomposition won’t occur

What are the 3 different types of peat

• fen peatlands

• Blanket peatlands

• Raised bogs

What is fen peatland

They form where groundwater meets the surface - at springs or at the edge of open water

What is a blanket peatlands

• Occur on flat hill tops where rainfall is very high

• Most common in the uk

What is a raised bog

Occur in valley bottoms where soils are saturated due to the frequent arrival of through flow and overland flow from the slopes above

What are some of the important functions of peatlands

• rich biodiversity

• Good for human use

• Help preserve a record of past landscapes

What % of the earth surface does peatland cover

3%

Do they sequester more carbon than other vegetation

Yes they store more carbon than all over vegetation in the world and 2x more than what’s stored in all forests

How is peat land good for human use

They can provide safe drinking water and help prevent floods

How can peat be degraded

• it forms in waterlogged anaerobic conditions when partially decomposed organic material mixes with peat soils to make the largest long term carbon store in the biosphere

• In forests like Indonesia when trees are removed this allows for water to flow away and sunlight and oxygen to enter the peat

• This leads to the peat drying out and degrading which reduces the carbon stored in the peat

• The carbon converts to CO2 and moves from the biosphere to the atmosphere

• If this continues then peat lands will disappear and previously sequestered carbon cannot be returned to the store

What is an example of a positive feedback loop

• climate change increases temperatures

• In the arctic the permafrost melts and in both the arctic and the tropics peat dries out

• Drier peat catches fire and roots burn

• Releases CO2 and other greenhouse gases into the atmosphere

• Climate change

What’s an example of a negative feedback loop

• reduction in peat accumulation due to drying out of peat

• Trees become uprooted and unstable which makes cavities in the peat that can be filled with water

• Waterlogged conditions are increased

• Peat accumulation resumes

Does a positive feedback loop have a positive outcome

No

Does a negative feedback loop have a negative outcome

No