Bogs are wetlands that accumulate peat and occur where the water at the ground surface is acidic and low in nutrients. They have a distinctive group of plant and animal species but this habitat is becoming increasingly rare, particularly in lowland Britain. The peat of the East Anglian fens was all formed by bogs thousands of years ago. Lowland bogs are some of the rarest habitats in England.
Very small pockets of bog remain at Holme Fen and Woodwalton Fen. Sadly, due to drainage around Holme Fen, its bogs have been drying out and bog species disappearing. An example is sphagnum moss, once plentiful and used for centuries for dressing wounds. However, some of the bog plants have maintained a very precarious foothold in Holme Fen and their future will be more certain as water levels are again raised.
Heaths are dryer habitats, characterised by open, low growing woody vegetation. There are also very small pockets of wet heathland in Woodwalton Fen and Holme Fen. Many more plant species thrive in wet heaths such as fen woodrush which is not found anywhere else in the country.