Culm grassland

Introduction

Culm grassland is a unique lowland mire habitat that developed above a geological formation known as the Culm Measures. It is confined to Our area of Devon and Bordering areas of Cornwall. The majority of the formation consists of shales and thin sandstones although there are also areas of slate, limestone and chert.

The geology of the Culm Measures has given rise to acidic, clay soils that are poorly drained in most places. In addition, we are all aware that this area experiences a relatively high rainfall which makes the soil rather damp as anyone who has lost their wellies in the mire will testify.

Unfortunately, large areas of Culm grassland have been lost in the last hundred years as a result of improved farming techniques and forestry. Up to 92% has been lost but there is currently a programme to stop and hopefully reverse this decline. Here in Halwill Parish we are lucky enough to have one of the largest remaining areas of Culm Grassland on Hollow Moor and it's surrounds.

The Culm is not a natural habitat but rather is created and maintained by centuries old grazing practices. If these areas were left to nature they would soon become dominated by areas of scrub woodland, of much reduced conservation value.

Species associated with culm grassland

Flora

The Culm grassland in Halwill comprises a patchwork of different plant communities, mostly purple moor-grass dominated mires and wet heaths, but the peripheral areas have large areas of rush pasture, ponds and unimproved grazing land. There are scattered trees throughout the Culm mainly willow and birch species, though sessile oak and ash are also common. The fields of the culm are separated by hedges and boundaries of birch, hazel and willow. This mixed habitat encourages great biodiversity, a walk through the moor never fails to surprise and delight with the species which are encountered. In early summer the moor can be a riot of colour with thousands of orchids in bloom. We have an abundance of heath-spotted orchids, lesser butterfly orchids and southern marsh orchids, in addition to a number of other plants of conservation interest such as whorled caraway, wavy St John's-wort and marsh cinquefoil. Wetter areas support sharp-flowered rush, ragged robin, marsh bedstraw, meadowsweet and wild angelica, while the drier areas hold such species as meadow thistle, tormentil, devil's-bit scabious, saw-wort and heathers (ling and cross-leaved heath). Where the soil is waterlogged, bog vegetation including sphagnum mosses, bog pondweed and sedges develop.

Fauna

The diverse flora supports several butterflies including marsh fritillary, small pearl-bordered fritillary, wood white, marbled white, dingy skipper and small heath. Other insects found on the Culm include the nationally scarce narrow-bordered bee hawkmoth, double line moth and keeled skimmer dragonfly.

There is a wide range of bird species associated with the Culm. Birds of prey are well represented with barn owl, tawny owl, hen harrier, marsh harrier, merlin and osprey being amongst those which you may be lucky enough to see. Other scarce birds which depend on the Culm include: curlew, snipe, woodcock, willow tit, reed bunting and grasshopper warbler and tree pipit. Amphibians not surprisingly, are well represented with common frog, toad, smooth and common newts all be present. Common lizard, adder and grass snake all found across the region.

Mammals that occur include dormouse, harvest mouse, fox, roe and red deer, badger and otter.