On Tuesday Amee, Peter and myself went out to Blawhorn Moss to have a look at the drainage ditches on the north side of the bog. It was great to get out as I haven’t spent much time on the bog at Blawhorn yet, and it was Peter’s first trip to the reserve.
On our way out we flushed two red grouse. I wasn’t quick enough with the camera but we saw signs that they had been around that area.
Amee took us to several ditches across the reserve and pointed out the evolution of damming techniques used.
Ditch damming first began on Blawhorn ~40 years ago and they started by using wooden piles sunk down into the ground. These wooden dams weren’t particularly successful as many of them are now rotten and falling apart. However, they did significantly slow the flow of water off the bog preventing further erosion from happening.
When these wooden dams began to fail and water was leaking through they added plastic piling behind them to reinforce the dam.
For the deepest ditches on the reserve, where the flow of water was much faster, steel shuttering was used to block the ditch as it can hold back a lot of water.
We were amazed by the size of the largest ditch (pictured below) where there appeared to be the most erosion and limited vegetation growth on top of the exposed peat.
The main aim of these techniques to block ditches is to hold water on the bog and prevent it from flowing off. This should raise the water table and reduce the amount of erosion to the peat.
Peat accumulates at 1mm per year – so it takes 1000 years to form 1 metre of peat! That means that a huge amount of carbon is stored in peatlands and is released when they are damaged. This is why we want to minimise the amount of erosion on the bog.
As well as being a nice day out for us, it is important that we monitor these dams so that we are aware of any improvements that need to be made to ensure that they are still working in the long term.