Holme Fen Silver Birch

Terry Brignall, All Aspects Photography

Toads at Holme Fen

Terry Brignall, All Aspects Photography

Wildlife of Holme Fen

Habitats

Holme Fen National Nature Reserve is one of four remaining fragments of the ancient wild fens. It occupies an area that, hundreds of years ago was on the shores of Whittlesea Mere – the largest lake in southern England.

Following drainage of the mere and surrounding area, Holme Fen rapidly dried out and became a Silver Birch woodland – the largest and finest of its type in lowland Britain.

Between the 1960’s and the 1980’s, peat cutting was permitted and this created two deep hollows that filled with rainwater and formed meres. The meres have islands and shallow banks which encourage birds, dragonflies and marsh plants such as Golden Dock.

There is also still a 12-acre area of unusual acid grassland and heath, and a small and precious area (2½ acres) of remnant raised bog – an echo of the habitat that dominated the site centuries ago.

These mixed habitats offer shelter and food for a rich variety of wildlife.

Birds

In winter, Siskins and Redpolls feed amongst the Birch and Alder. In summer, warblers, tits and woodpeckers nest in the woodland.

Burnham’s and Boston’s Meres attract wildfowl in large numbers during the winter months. Greylag Geese, Mallard and Coot dominate, along with smaller numbers of Gadwall, Teal, Tufted Duck, Shoveler, Wigeon. Look out for Great Crested Grebes displaying in the spring and for Cormorants raising their young in nests on the islands.

Trees

Some trees were planted in the 19th century to create game cover, but most are self-seeded and form mixed-age woodland blocks. It is the abundance of Silver Birch that give Holme Fen its particular visual appeal in every season. In damper areas, Alder grows vigorously and is the second most common tree on the reserve.

The large Oaks, Scots Pines and Larches were planted, but wild saplings of Oak, Holly and Yew are springing up throughout the wood. Eventually, these trees will grow up through the birch to form a mixed woodland. Sallow, Alder Buckthorn, Purging Buckthorn and Hawthorn scrub grows around woodland edges and glades. Elder is particularly successful and is found beneath the tree canopy as well as in the open.

There are Rhododendrons close to the wartime charcoal bin that were planted earlierin the 20th century. These are not part of the native British flora and so are of little value to wildlife, but visitors enjoy seeing the displays. However, Rhododendrons are invasive, so they are cut back regularly to prevent them spreading through the wood.

Bog, heath and fen plants

The fragments of bog are relics of a 'raised bog', created by peat which built up to form a dome above the water table and surrounding land. Sphagnum Mosses, Cross-leaved Heath and Bog Myrtle were once common here and their precarious foothold is maintained today by means of scrub cutting and careful control of water levels.

In drier areas a heath habiat has developed with Heather (Calluna vulgaris) and Wood Sage (Teucrium scorodonia). The grassy glades and 'poor fen' support typical fen sedges and rushes as well as more unusual plants like Meadow Rue, Climbing Corydalis (Ceratocapnos claviculata) and the very rare Fen Woodrush (Luzula pallidula) which is found nowhere else in Britain.

Butterflies, dragonflies and other insects

A rich variety of insects thrive in the woodland, meres and fragments of ancient fen. In particular around a third of the UK’s dragonfly species can be found at Holme Fen.

Open patches of grassland support what is thought to be the largest population of Small Copper butterflies in the county. (Image left by Barrie Galpin)

White Admiral butterflies can be seen gliding along the woodland rides, flying from trees to the woodland floor.

Fungi

The development of fungi on Holme Fen is helped by the short life cycle of the Silver Birch trees (about 80 years) and over 500 species of fungi have been identified on the reserve. Look out for the well-named Horse Hoof fungus growing on the Silver Birch trunks and also the bright red Fly Agaric. (Image right by Terry Brignall, All Aspects Photography).

It was the rich variety of fungi that led to Holme Fen's designation as a Site of Special Scientific Interest.