24.8 Ecosystem management - peat bogs
Peat bog - region of wet, spongy ground that contains decomposing vegetation. Undisturbed peatland is a carbon sink, store of carbon dioxide. However once it dried, it can be used as fuel. As well as releasing thermal energy, it releases carbon dioxide into the atmosphere.
It takes many thousands of years for peat bogs to form, the preservation of existing peat bogs is therefore an important component in preventing further climate change.
As well as being used as fuel, peat is also important for farmers and gardeners, who mix it with soil to improve soil structure and to increase acidity. It has very favourable moisture-retraining properties when soil is dry, and prevents excess water killing roots when soil is wet. Although peat can store nutrients, it is not fertile itself. Commercial peat extraction to supply gardeners and nursery growers is a major threat to this ecosystem.
Ecosystem
Peat forms when plant material is inhibited from fully decaying by acidic and anaerobic conditions. This normally occurs in wet or boggy areas, and therefore peat is mainly composed of wetland vegetation including mosses, sedges and shrubs.
The plants that grow on peatlands, such as sphagnum mosses, bog cotton or cottons edge have adapted to grow and thrive in wet conditions and few nutrients. Bogs also support a wide range of insects like butterflies, moths, dragonflies, and damselflies. The lack of predators and human disturbance makes some peatlands ideal of birds to nest and bring up their chicks. The abundance of insects, spiders and frogs plus nutritious vegetation and berries, provides food for many species. The large areas of open ground provide ideal hunting grounds for birds and prey.
Loss of ecosystem
Lowland raised bogs are one example of a peatland ecosystem. They are a rare a threatened habitat. In the Uk, the area of relativity undisturbed lowland raised bog is estimated to have diminished by over 90%from around 950 km2 to only 60 in the last 100 years. It is essential that remaining areas are conserved to maintain biodiversity- this will also contribute to flood management , erosion control downstream and carbon storage.
The greatest decline has occurred through afforestation (establishment of aforest or stand of trees in an area where there was no forest), peat extraction and agricultural intensification, including land drainage have all contributed to drying out of the pogs.
Conserving lowland bogs
Key is to maintain or restore appropriate water levels
Ensuring that the peat and vegetation of the bog surface is as undisturbed and as wet as possible. Most bogs are surrounded by ditches to allow water to run off, preventing flowing or nearby land. In restoring a bog, ditch blocking may be required for a period of time to raise the water table to the bog surface.
Removal of seedling trees from the area. Trees have a high water requirement due to transpiration. Therefore any tree seedling that has the potential to remove water from an area of peatland, or to reduce its ability to support bog vegetation, should be removed to maintain water levels in the area.
Using controlled grazing to maintain the biodiversity of peatland. Grazing ensures a diverse wetland surface in terms of structure and species composition. This is turn provides a wide range of habitats for many rare insect species.
Land use threatens the existence of much of the remaining peatlands. Many organisations working on this including, The Wildlife Trusts, Natural England, Royal society for the protection of birds. It is hoped that, through the conservation work of these, an appropriate can be met.