Description
Holme Fen today, is largely a woodland site, dominated by birch, however its history is very different. It was once on the edge of the former Whittelsey Mere basin, which consisted of a mix of raised bog, reedbed and fen habitats. After various failed attempts during the 17th century, this wetland was finally drained for agriculture in 1851, changing the habitat for ever. The Holme Fen Post which was sunk in at ground level in 1850 shows the phenomenal rate of shrinkage of the peat over the subsequent years as today, it sits at around 4m above ground level.
The historical draining of the mere would have seen the loss of many fenland species, but the reserve today is still nationally important for wildlife and is particularly noted for its range of fungi, of which over 500 species have been recorded.
Fortunately the area that is now Holme Fen was considered too wet, even after drainage, to be put under the plough. This meant the peat has not been damaged extensively on the site, except for the two areas which were cut and are now Burnham McPhail’s mere and Boston’s mere, (named after past wardens). The peat currently remains at around 3m deep over much of the site.
Holme Fen is part of the Great Fen Project, an ambitious project aiming to create a rich fenland landscape between and around this site and Woodwalton Fen. Natural England is in partnership with the Environment Agency, The Wildlife Trust, Huntingdonshire District Council and Middle Level Commission to achieve the vision of the Great Fen which started with the purchase of 82ha of land, to the North of Woodwalton Fen in 2002. Since then the project has managed to acquire approximately 60% of the total project area and at the end of 2012 almost 1500ha was under conservation management.
Habitats
Open water
Areas of open water remain at Burnham’s Mere and Boston’s Mere where great crested grebe, little egret, heron and cormorant nest. Other smaller meres are also present on site.
Remnant bog and wet heath
A number of plants which are relics of the former mire habitat survive, including saw sedge, cross leaved heath, purple moor grass and fen wood-rush.
Birch woodland
Today woodland is the dominant habitat and Holme Fen is now the largest lowland birch woodland in the UK, the woodland having developed after the drainage of the former Whittelsey Mere basin in 1851.
Although dominated by birch trees other species such as oak, alder, yew and holly are also present.
Key species
Fen woodrush
The reserve has a huge list of plants many of which indicate the length of time that recording has been carried out on this site.
Fen woodrush, marsh dock and annual pearlwort are all nationally notable species. Fen woodrush is an incredibly rare plant, critically endangered and considered one of the UK’s rarest native wildflowers. It was first discovered in the UK in 1907, and is found only at this one site. Over the last century, it has been feared completely extinct multiple times, only to reappear unexpectedly from buried seed banks when the ground was disturbed.
Bog myrtle is one of the remnant species of the old fen, and this highly aromatic plant can withstand acidic, waterlogged and nutrient poor conditions.
Dragonflies
The site has a good variety of dragonflies including hairy dragonfly, variable blue damselfly, scarce chaser, black-tailed skimmer, ruddy darter and Norfolk hawker.
Silver-washed fritillaries frequent the woodland rides and a range of other insects are present including our largest sawfly species, the giant birch clubhorn sawfly.
Siskin and redpoll
Many bird species typical of woodlands can be seen, these include the siskin and lesser redpoll, two of the UK’s smallest and most agile finches, who rely heavily upon the seed production of birch trees. Resident birds will be joined in winter by migrants from Scandinavia, such as redwing and fieldfare.
Nightingale are still present but in low numbers.
Fly agaric
The site has a huge list of over 500 species of fungi. These include wonderfully named crimpled gill, violet coral, angel’s wings and pink waxcap as well as more common species associated with birch woodlands such as the fly agaric. This toadstool is probably the most recognised of fungi and got its name from the medieval use of it to control household flies.
Grass snake
Holme Fen and the wider Great Fen project support native reptiles and amphibians like the grass snake and common lizard, alongside creatures like great crested newts and common toads.
Further info
Cambridgeshire NNRs:
https://www.greatfen.org.uk/holme-fen
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