Astley Moss Restoration Project
Astley Moss Northern Area of Astley Moss - a project update written by Chris Turner (Dr). Peatland Restoration Consultant to Peel Environmental
"The Project aims to restore Lowland Raised Bogs in the area and engage local communities with this fascinating habitat.
As with Astley, following the demise of WSH, responsibility for restoration fell onto Peel. Again, as at Astley, Peel have retained me as a consultant to help them undertake this restoration.
Peat extraction ended on the northern area of Astley Moss between 2000 and 2009. Restoration began soon after peat extraction stopped. On average about 1 to 2 metres of peat remained in the ground when peat extraction ceased. Photo 1 shows what the area was like before any restoration began.
The aim of the restoration scheme at Astley Moss is to recreate natural conditions suitable for a relatively quick return to active bog across the vast majority of the site, without the need for any further intervention from man. An active bog is one that has a substantial sphagnum moss cover which grows roughly 1 to 2 cm a year. This in turn lays down about 1 to 2 mm of peat a year. Peat is partially decomposed sphagnum moss. The moss is only partially decomposed because the environment is anaerobic, due to it being waterlogged, and very acidic, due to the properties of sphagnum mosses. It is hoped that the Northern Area of Astley Moss will become an active bog once again in the next 10 to 20 years.
The basic conditions that are required for restoration to active bog are
Surface water must be between 5mm below or 10mm above the surface all year round.
This water must be ombrotrophic, i.e. be pure rainwater.
Cotton grasses and sphagnum mosses need to be encouraged to grow across the site.
These conditions might sound easy and simple to create – they are not! Theoretically it should be possible to create totally flat surfaces across large areas, but in practice it is very difficult, as peatlands move and swell up and down as water flows in and out. Without totally flat surfaces, it is almost impossible to achieve condition 1, so even after substantial surface recontouring, one inevitably ends up with some areas that are too wet and other areas that are too dry and the Northern Area of Astley Moss is just like this.
Lagoons naturally form in the wetter areas. These water bodies are generally too deep for sphagnum growth (and wave actions on the surface can destroy bunds). However, cotton grasses and sphagnum mosses grow around the edges of these lagoons and gradually, infill occurs, and these cotton grasses and sphagnum mosses move towards the centre of the lagoons (see photo 2).
Bigger problems are encountered in the areas that are too dry. In these drier areas unwanted plants (we usually call them weeds!) thrive and these weeds prevent the good guys (cotton grasses and sphagnum mosses) from developing. These weeds often spread rapidly. The main weed on many peat restoration sites is birch and this is the case on Astley Moss. Birch seedlings quickly spread across drier peat areas and as the seedlings grow into shrubs and trees, they take over the whole area. Birch shrubs dry out the peatland still further, both by preventing rainfall reaching the ground and by extracting water from the ground via evapo-transpiration. Controlling birch growth is a major issue on Astley Moss. Simply cutting them down potentially does more harm than good, as birch quickly regrows from stumps and the new regrowth can be more rampant than the original shrub!
If the surface water level cannot be maintained between 5mm below and 10mm above the peat surface all year round, then it is better to see areas that are too wet rather than too dry. Restored peatland areas that are too wet will form active bogs eventually, even if nothing else is done to the site, whereas areas that are too dry will never form active bogs, without further intervention from man. An example of a dried bog can be seen next door to Astley Moss, at Botany Bay Wood. Here, trees and shrubs dominate the site, meaning it will never become wet enough to again support active bog – unless action is taken to remove these trees and at the same time permanently raise the water table to at, or just above, the peat surface. It is good to know that plans are in place to do just this at Botany Bay Wood.
Recent work at the Northern Area of Astley Moss has concentrated on two aspects. Firstly a concerted effort has been made to control birch. Last summer, large areas of birch were cut down and flailed within area 1 (photo 3). At the same time, the main water outflow was blocked off and a couple of new water channels were cut to encourage water to flow into some of these drier areas. This has resulted in area 1 being much wetter than in previous years. Hopefully this will result in few of the cut/flailed birch from re-growing. Only time will tell if this has been successful, but the initial findings are encouraging.
The second part of the recent work has been to try to get more of the excess water in area 3 to flow into the drier area 2 (via area 1). This has been achieved by cutting a number of extra channels in between these three areas (photo 4). GPS survey work indicated that the water level in area 3 was a few centimetres higher than in levels 1 and 2, so the water would flow in the direction we wanted! As with the birch control, it is too early to say if this has been successful, but water levels rose considerably over the winter of 2017/18 in area 2, but not so in area 3, so the early signs are encouraging.
So the future of the Northern Area of Astley Moss looks good. Many sections, notably in areas 3 and 4, have sizeable carpets of sphagnum mosses growing (as can be seen in photos 5, 6, 7 & 8). These areas will expand year by year. Areas 1 and 2 have been a little disappointing recently but were given a boost in summer 2017 and it is hoped these areas will soon be showing further signs of active bog growth."
Chris Turner (Dr).
Peatland Restoration Consultant to Peel Environmental