Bogs in a changing climate

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Blawhorn Moss NNR and Flanders Moss NNR

As bogs receive all of their water from rainfall then they are very susceptible to a changing climate. Increasing temperatures and different rainfall patterns causes stress to a bog in the following ways:

  1. A loss of species that are only found on bogs and a change in species composition towards more one that are more stress tolerant i.e. like drier conditions.
  2. A lowering of the water table.
  3. Drying of the surface of the bog which allows trees and scrub to spread which then further increase surface drying
  4. Increased greenhouse gas emissions from drying, exposed peat
  5. Increased erosion of dry, exposed peat, which reduced water retention

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The effects of a long dry spell on Flanders are all too obvious this summer as noted in the blog here .

So how do we make Flanders more resilient to the climate change that is happening? What do we need to do to get it to a state that it can withstand these changes and still be home for special wildlife?

That is where our bog restoration work comes in. At Flanders in 1992 there over 40km of ditches and channels across its surface and this was having a considerable effect is speeding up the drying process. Blawhorn also had a considerable number of ditches across its surface.  But now the majority of those ditches have been dammed so bringing the water table to the surface. This restores the surface level of sphagnum which then soaks up any rainfall and helps to keep bog wet during dry spells.

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Trees are a problem as not only do they suck water out of the moss but in summer the leaves and branches intercept the rain so preventing it from reaching the bog surface. The removal of trees and scrub from large areas of Flanders has increased the wetness of the bog and low levels of grazing helps to keep the bogs clear of trees.

By revegetating the bog surface with sphagnum the carbon-rich peat is not released to the atmosphere but is locked up, and the process of peat formation can start so storing more carbon.

Dry bogs are vulnerable to damaging wildfires but once rewet there is more moisture in the dead heather, mosses and litter, fire damage will not be so severe and the higher water table increases these bog’s resilience to deep peat burn in future.

One of the encouraging things this summer is that several bog anoraks who get round a lot of bogs have commented on how wet Flanders is around the boardwalk compared to other peatlands. This is really encouraging as it seems that the restoration works are starting to make the special sites more resilient to the changing climate. After all we can do without bogs, they tick so many boxes – here are a few.

  1. An effective carbon ‘sink’ rather than a source (and so mitigating climate change rather than contributing to it).
  2. Slowing the release of rainfall into streams and rivers, reducing the frequency and severity of flooding.
  3. A place to see unique bog-loving wildlife.
  4. An accessible place to go to for recreation (figure 5). With  boardwalks now installed, you can now access the bogs and see the site for yourself.

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