The Importance of our Natural Bog – and the Impacts of Bog Drainage
A peat bog is a particular type of wetlands which are waterlogged only by direct rainfall and are likely to have a moisture content of greater than 95% in the undisturbed state (“there are almost more solids in milk than in peat”). Consequently, a peat bog contains only those nutrients found in rainfall, which is slightly acidic and almost devoid of nutrients. Bog surfaces also often have areas of standing surface water. It is this waterlogging that creates a peatland and allows it to function
This contrasts with fens where groundwater, enriched by the chemistry of mineral soils, causes waterlogging. Waterlogging in both bogs and fens prevents the complete decomposition of dead plant material. It is this un-decomposed plant material that steadily accumulates as a thickness of peat, increasing by up to 1mm each year (or by 1 meter in 1,000 years)
A peat bog can thus be thought of as a tree, much compressed in the vertical dimension. The acrotelm being the thin living surface layer of peat-forming vegetation, generally between 10 – 40 cm deep and represents the thin canopy consisting of leaves on a tree, while the catotelm is permanently waterlogged peat store which may be several metres deep represents the branches and trunk. The acrotelm supplies plant material which then forms peat in the catotelm. Without an acrotelm a bog cannot accumulate peat or control water loss from the catotelm. In a tree the water travels upwards through the trunk to the leaves, whereas it a bog it travels from the living canopy downwards into the catotelm.