Askham Bog formed in the Vale of York in a hollow which was flooded by meltwater from the last glacial retreat about 15,000 years ago.

The appeal by the community and Yorkshire Wildlife Trust enlisted the help of Sir David Attenborough, who said that "it is our collective responsibility to save it."

The large habitat diversity may be partly explained by the many successional stages present which generally become more advanced towards the centre, in turn related to spatial differences in topography and soil pH.

Other tree species growing alongside oak in the acid centre include hazel, alder buckthorn and rowan.

[8] In recent decades, sulphur deposition on the bog has increased due to polluted air moving downwind from a large industrial area with coal-fired power stations.

Askham Bog also holds the largest and most north-eastern colony in England of the rare gingerbread sedge Carex elongata,[9] and is renowned for the presence of royal fern.

The vegetation of Askham Bog can be divided into two main groups, reflecting the broad underlying dichotomy between basic and acidic soil.

The other community is a species-poor acid one towards the centre, including species such as Sphagnum palustre, purple moor grass, Rubus fruticosus and honeysuckle.

[2] Known resident species include marsh tit, willow tit, treecreeper, kingfisher, goldcrest, bullfinch, tawny owl, buzzard, sparrowhawk and sometimes green woodpecker[11] Winter visitors include fieldfare, redwing, brambling, siskin, lesser redpoll, goldfinch, snipe, jack snipe, woodcock, coot and sometimes grasshopper warbler.

[2] Askham Bog is nationally recognised for its diverse invertebrate fauna, including a variety of water beetles such as Haliplidae, Noteridae, Dytiscidae and Gyrinidae.

[1] There is a large proportion of wetland indicator spider species given the relatively dry status of the reserve and gradual encroachment by trees.

This may be because the present spider community reflects historic moisture levels within the bog and is yet to completely respond to the habitat changes.

[11] From the early Roman period until the mid-18th century, Askham Bog and its environsy appeared to have been intensely exploited for peat as fuel.

The severe penalties imposed by these legal restrictions reflect the attempt by the local authorities back then to counteract the damaging intensity of peat extraction at Askham Bog.

In turn, a lowering of the acid peat layer through extraction would have allowed base-rich groundwater to inundate the centre, transforming it into an open fen.

To achieve this, the National Conservation Corps was enlisted to create more open water by digging ponds and blocking dykes, along with scrub clearance in the damp cotton-grass areas.

[12] Most of the species-rich fen areas are grazed by Exmoor ponies to encourage early successional plant species such as marsh orchid and meadow thistle, and to suppress vigorous grasses, reed and saplings.