British NVC community W4

The field and ground layers are sometimes formed of either a lawn of Sphagnum or a taller sward of purple moor-grass or, on less moist soils, a dense cover of bracken.

[3][1] Fungi are often abundant, with birch polypore on the rotting tree stumps and tawny grisettes and various types of Russula on the boggy ground.

[5][6] Birch woodland (usually W4 but sometimes W10 or W16) is often considered problematic on heathland nature reserves, particularly as the decomposing leaf litter can suppress the ground flora.

This showed how the birch had colonised the ground around Whittlesey Mere shortly after it had been drained, and the tree cover was fairly uniformly composed of 85 year-old specimens at the time of survey, dating the establishment of the wood to around 1865.

[2] At first this was thought to be a natural and fairly stable ecological feature,[11] but later it was found to have been triggered by 19th century drainage operations, as at Woodwalton.