Flora of Bishop Middleham Quarry SSSI 2011 Compiled and published by John Durkin, BSBI recorder for County Durham [email protected] Bishop Middleham Quarry, an SSSI and a Durham Wildlife Trust reserve, is a disused magnesian limestone quarry which supports a very rich flora, including the best national population of the Dark Red Helleborine, Epipactis atrorubens. For botanists visiting the county, it is one of the must-see nature reserves. It is located at NZ3332, on a minor road close to the A1(M) and 3 miles from Durham Services, junction 61. The reserve covers 8.60 hectares. Timing The reserve is at its best from June to August. The Dark Red Helleborines flower in July and August. Access The entrances to the site are at grid reference NZ331326 about a mile down a narrow lane which leads west off the A177 south of Coxhoe, just south of the Hare and Hounds pub. There is limited roadside parking opposite the two entrances, in the narrow lane to the west of the reserve. The reserve is accessed from stiles from the lay-bys. Though most of the reserve has quite rugged terrain, the area immediately inside the reserve from the northern lay-by is a fairly level area of species-rich grassland and easily accessible rocky areas. Most of the mag-lime flora, including Blue Moor Grass and Dark Red Helleborine can easily be found here. Beyond this flat area, the quarry is on several different levels, accessed by steep but well-maintained steps. There are a number of vertical cliff faces. The Magnesian Limestone The magnesian limestone is a special group of limestones laid down in the Permian period. 270 million years ago. At that time, Bishop Middleham was part of a barrier reef on the western edge of the warm, shallow, Caribbean-like Zechstein Sea. Limestone is usually calcite, CaCO3, but the magnesian limestone is mainly dolomite, CaMg(CO3)2. There are several forms of mag-lime, ranging from soft and crumbly to very hard. The distinctive type of limestone and the mid-Britain location gives the mag-lime area of County Durham a unique combination of northern and southern species, and in particular southern species reaching their northern limit here. History The quarry ceased to be worked in 1934 and was left to re-vegetate naturally. It is located in the middle of the magnesian limestone area, so there was strong colonisation of the classic magnesian limestone flora, which was much more widespread in the general countryside in those days. Now, the magnesian limestone flora has gone from most farmland, and is mainly restricted to the coastal strip and to isolated nature reserves. The quarry was designated as an SSSI in 1968 and became a Durham Wildlife Trust reserve, leased from the Church Commissioners, in the 1970s. There are large modern quarries to the south and west of the reserve. Habitats The upper level of grassland by the lay-by has a dense sward and, although it is secondary, is similar to original mag-lime grassland. Blue Moor Grass, Cowslips, Fragrant Orchids, Thyme, Bird’s-foot Trefoil, Rock Rose and Milkwort are frequent. The Rock Rose supports one of the largest colonies of the Northern Brown, or Durham, Argus butterfly, which is on the wing in June and July. Bishop Middleham Quarry has excellent populations of a number of more common butterfly species. In the photograph below, several people are walking on the level area, and you can see the steps going down to the quarry floor. The entrance is at the top left. From the first grassland, steps descend to the floor of the quarry, where there are bare rocky areas and vegetation is sparser. This is the main area for Dark Red Helleborine, and also has many Fragrant Orchids and a few small plants of Dropwort. Rocky areas at the northern end of the quarry support ferns such as Male Fern, Hart’s Tongue, Maidenhair Spleenwort and Black Spleenwort. The eastern side of the quarry has a mixture of very bare and well vegetated habitats. The very bare areas, with a thin gravelly soil, are the best places to find tiny plants of Moonwort. The more vegetated areas have Pale St John’s Wort, Pyramidal Orchid and Northern Marsh Orchid. The southern end of the reserve has dense scrub and developing woodland growing on the original and more fertile spoil from the quarry. An area of willow scrub has Tea Leaved and Dark Leaved Willows. The reserve cannot easily be grazed to maintain the grassland, so the Wildlife Trust puts in a lot of effort to prevent the spread of scrub into the richer areas of grassland and to prevent the grasslands becoming too coarse. The Dark Red Helleborines and the Durham Argus butterfly are monitored each year. This account is based on 1400 botanical records for the reserve, including an intensive survey in 2011. Further information can be obtained from the Natural England and Durham Wildlife Trust websites, and from a booklet “MAGical Meadows” available from the Wildlife Trust. Species The nationally rare and scarce species and the species which are rare in the county are described in detail. All of the species recorded for the reserve are listed at the end of this account. Dark Red Helleborine Epipactis atrorubens Nationally Scarce The number of flowering spikes varies from year to year, but is usually several thousand, which is the great majority of the national population. This orchid reproduces by abundant seed. It is easily found here, mainly at the northern and western parts of the quarry in thin soils and rock ledges. Strangely, it was first recorded in County Durham in 1911, when it may have been a recent arrival. Smaller numbers can be seen at Raisby SSSI and Thrislington NNR. Blue Moor Grass Sesleria caerulea Nationally Scarce The headquarters of this grass are on the North Pennine limestones, but it is also characteristic of the magnesian limestone. It can be found on almost all of the inland magnesian limestone sites, and at some coastal grasslands. It is abundant at Bishop Middleham Quarry, often dominant in level grassland and on rock ledges and faces. It flowers early in the year and the stems lengthen as the seeds ripen. Pale St John's Wort Hypericum montanum Near Threatened This perennial is at the northern edge of its British range here in County Durham. It is most frequent on the south-facing open woodland slopes at Castle Eden Dene NNR and Hawthorn Dene SSSI. Here at Bishop Middleham Quarry it favours the edges of scrub and rough grassland in the middle of the reserve. Dropwort Filipendula vulgare Another flower at the northern edge of its range, Dropwort is a “County Scarce” species. There are only a handful of plants at Bishop Middleham, growing in thin soils, and not flowering every year. They can be found in the centre of the quarry and also in the north east corner. Though it’s a southern species, its county HQ is at the northern tip of the magnesian limestone, at Cleadon Hills. Moonwort Botrychium lunaria The thinnest, gravelly soils at Bishop Middleham support several hundred tiny plants of this curious fern. It isn’t a nationally or county rarity, it is included here because Bishop Middleham is one of its best county sites. Purple Milk-vetch Astragalus danicus Frog Orchid Dactylorhiza viridis Endangered Vulnerable This flower was formerly frequent on the This orchid has not been recorded at inland magnesian limestone and at the Bishop Middleham since 1972. It has coast, but it has declined very sharply and declined both nationally and locally, but is has almost gone from the inland sites. The still present at several nearby reserves, so last record from Bishop Middleham was in it could re-appear here. 1963. The reasons for the decline are unclear, as the habitat looks to be Other orchids still present at Bishop suitable. Middleham include Twayblade, Pyramidal, Bee, Fragrant, Common Spotted, Northern Marsh and a range of Common Perennial Flax Linum perenne Spotted/Northern Marsh hybrids. Nationally Scarce Not seen here since 1963, this plant must be extinct here, as its blue flowers would be hard to miss. The main county populations are at Thrislington NNR, just one kilometre to the west, and at Harton Downhill SSSI, near South Shields. Clockwise from top left- The quarry floor Blue Moor Grass Fragrant Orchid Milkwort Black Spleenwort Clockwise from top left- Northern Marsh Orchid Common Blue Butterflies Autumn Gentian Seed pods of Dark Red Helleborine Significant species are highlighted in green, and have a “most recent date”. Scientific name English name Most recent Acaena anserinifolia Bronze Pirri-pirri-bur 1970 Acaena novae-zelandiae Pirri-pirri-bur 1959 Acer pseudoplatanus Sycamore Achillea millefolium Yarrow Achillea ptarmica Sneezewort Aegopodium podagraria Ground-elder Agrimonia eupatoria Agrimony Agrimonia procera Fragrant Agrimony 1998 Agrostis canina Velvet Bent Agrostis capillaris Common Bent Agrostis stolonifera Creeping Bent Anacamptis pyramidalis Pyramidal Orchid 2011 Anagallis arvensis Scarlet Pimpernel Anchusa arvensis Bugloss 1970 Anisantha sterilis Barren Brome Anthriscus sylvestris Cow Parsley Anthyllis vulneraria Kidney Vetch Aphanes arvensis Parsley-piert Arabis hirsuta Hairy Rock-cress Arctium minus Lesser Burdock Arenaria serpyllifolia Thyme-leaved Sandwort Arrhenatherum elatius False Oat-Grass Artemisia vulgaris Mugwort Asplenium adiantum-nigrum Black Spleenwort 2011 Asplenium ruta-muraria Wall-rue Asplenium trichomanes quadrivalens Maidenhair Spleenwort Astragalus danicus Purple Milk-vetch 1963 Avena fatua Wild-oat Ballota nigra Black Horehound Bellis perennis Daisy Betula pendula Silver Birch Blackstonia perfoliata Yellow-wort Botrychium lunaria Moonwort 2011 Brachypodium pinnatum Heath False-brome Brachypodium sylvaticum False-brome Briza media Quaking-grass Bromopsis erecta Upright Brome Bromopsis ramosa Hairy-brome Calystegia sepium Hedge Bindweed Calystegia silvatica Large Bindweed Campanula rotundifolia Harebell Carex caryophyllea Spring-sedge 1968 Carex flacca Glaucous Sedge Carex nigra Common Sedge Carex panicea Carnation Sedge Carex rostrata Bottle Sedge Significant species are highlighted in green, and have a “most recent date”.