Unit 6: Changing carbon stores in peatlands over time

Question 1

What is peat?

Answer 1

Peat is a soil which over 80% is composed of partially decomposed organic matter, which has accumulated under certain condititions.

Question 2

What are the conditions which peat requires to accumulate?

Answer 2

• climate where precipitation exceeds evaporation
• waterlogged ground (impermeable rock, high water-table, drainage depressions in landscape)
• oxygen deficiency (anaerobic conditions)

Question 3

Where is high amounts of peat found?

Answer 3

The northern hemisphere. Links to geology as there is a lot of impermeable rock so the water cannot percolate downwards so it keeps the soil saturated.

Question 4

Describe peat coverage in the UK?

Answer 4

In the UK peatlands cover around 3 million hectares or 12% of the land area and store over 3.2 billion tonnes of carbon.

Question 5

What are the 3 main types of peatland in the UK?

Answer 5

Fen peatlands = in areas of low lying topography where groundwater meets the surface.

Blanket peatlands = occur on flat hill tops, with impermeable rocks where drainage is impeded.

Raised bogs = occur in topographical depressions/valley bottoms where drainage of water from the surrounding landscape accumulates.

Question 6

Whats an example of a Fen peatland?

Answer 6

East Anglian Fens

Question 7

Whats an example of a Blanket peatland?

Answer 7

The ‘Flow Country’ Sutherland, Scotland

Question 8

Whats an example of raised bog?

Answer 8

Whixall Moss, Shropshire/Welsh Border
(main case study)

Question 9

Describe peat in the carbon cycle?

Answer 9

Peatlands occupy 3% of the global land surface and are one of the earths major carbon sinks storing 500 gigatons of carbon. They are vitally important in the global carbon cycle.

Question 10

How does peat form?

Answer 10

Peat forms in waterlogged areas, lacking in oxygen and where the water is acidic. In these conditions’ decomposition is restricted so that dead organic matter doesn’t decompose. Over thousands of years peat accumulates at the rate of 1mm per year. Consequently, carbon is preserved and makes up 50% of the DOM.

Question 11

What happened with peat during the End of Devensian Glaciation (12000ybp)?

Answer 11

Kettle hole lake/depressions left by retreating glacier fills with water. Vegetation around the edges of the lake die and fall in.

Question 12

What happened with peat during Holocene (last 10000 years)?

Answer 12

Lakes became inhospitable for many plants and water species - decomposition is inhibited.

Question 13

Whats happening with peat in Present Day?

Answer 13

New types of plants such as sphagnum mosses, colonized the surface of the fen and as they dies and accumulated, transformed the fen into a swap bog. 80% is dead organic matter and of that 50% is carbon.

Question 14

Why is sphagnum Moss a key species in peat formation?

Answer 14

It can hold around 20 times its own weight in water, effectively acting as a sponge and helps maintain waterlogged conditions.
As it grows it takes up nutrients such as potassium and magnesium from the environment and releases hydrogen ions; hence making the water acidic typically below pH 4.5.
It releases a chemical called sphagnum which has antibacterial properties and reduces decay of organic matter.

Question 15

What are some human activity’s which threaten the peat bogs and impact on carbon and water cycles?

Answer 15

• Cutting Peat and burning it as a fuel (releases CO2)
• Cutting Peat and use in horticulture (gardening which has increased demand)
• Drainage of peat and use for agriculture or forestry

Question 16

Why is it bad to plant trees/invasive species in peatland areas?

Answer 16

Trees have a very high water uptak to support them which reduces the water table and drys peat out. Carbon is not stored in trees as long as it is stored in peat for. Invasive species eman there is more competetion.

Question 17

What are some management Activity’s which help restoration of Peatland and positively impact the carbon and water cycles?

Answer 17

• Blocking drainage channels (water table rises)
• Removal of invasive shrub and tress species ( increases soil storage)
• Re-seeding damage areas with sphagnum moss (reduces flood risk)

Question 18

Summarise peatland targets

Answer 18

At least 75% of the UK’s peatland is aimed to be restored by 2050.

Question 19

Describe carbon in a healthy and a damaged peatland?

Answer 19

Healthy = Peatland is a carbon sink
Damaged = Peatland is a carbon source

Question 20

Describe Fenn’s, Whixall and Bettisfield Mosses, Shropshire Case Study?

Answer 20

• They extend over 1000 hectares on the English/Welsh border and is the third largest raised bog in Britain, storing 3million tonnes of carbon. Its a National Nature Reserve, Site of Special Scientific Interest, a European Special Area of Conservation and a Wetland of International Importance.

Question 21

Describe the long history of interaction between humans and the natural environment at Whixall Moss?

Answer 21

• since the 18th century the bog has been drained for agriculture and peat extraction
• large scale drainage occurred in the 1920s for commercial peat extraction
• in the 1960s part of the area was planted with pine forests
• mechanised commercial cutting of peat began in 1968
• in 1989 the rate of cutting quadrupled and a campaign was launched to rescue the mosses
• in 1990 it was designated as a NNR ending drainage and peat extraction, and a restoration programme is ongoing.

Question 22

Summarise the restoration of these mosses at Whixall Moss

Answer 22

• £5m of European funding plus funds from the National Lottery
• Shropshire Wildlife Trust in partnership with Natural England and Natural Resources Wales are restoring 660 hectares
• Dams and plastic piling reduce runoff from old drainage ditches
• 150 miles of bunds reduce the flow of surface runoff
• Replanting of sphagnum moss retains rainwater

Question 23

How is pollution a issue to the peat?

Answer 23

Ammonia from cattle and chicken farms nearby reduces the acidity in the bog.