Transactions of the Norfolk and Norwich Naturalists' Society
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t?'. J-HG TRANSACTIONS OF THE NORFOLK & NORWICH NATURALISTS' SOCIETY Vol. 31 Parti (July 1997) the j natural ! HISTORY MUSEUM 2E J !> L IP97 rv " - • TRANSACTIONS OF THE NORFOLK AND NORWICH NATURALISTS' SOCIETY ISSN 0375 7226 Volume 31 Part 1 (July 1997) Editor P.W.Lambley OFFICERS OF THE SOCIETY 1997-98 President: Dr Ian Keymer Vice-Presidents: Dr R. Baker, P.R.Banham, A.L.Bull, K.B.Clarke, E.T.Daniels, D.A.Dorling, K.C.Durrant, R.E.Evans, R.Hancy, R.Jones, Mrs J. Robinson, M.J.Seago. Chairman: D.L. Pauli, 8, Lindford Drive, Eaton, Norwich NR4 6LT. Secretaiy: Dr A.R.Leach, 3, Eccles Rd, Holt, NR25 6HJ Assistant Secretaiy: J.F.Butcher, 4, Hillvue Close, New Costessey NR5 ONQ Treasurer D.I. Richmond, 42, Richmond Rise, Reepham, NR10 4LS Membership Committee: Mrs A.Brewster (Chairman), C. Dack, (Secretary) Programme Committee: J.B. Mott (Chairman), Dr S.R.Martin (Secretary) Publications Committee: D.A.Dorling (Chairman), P.W.Lambley, Dr M.Perrow, M.J.Seago, (Editors) Research Committee: M.Poulton (Chairman), M. Baldwin (Secretary) Hon. Auditor J.E.Timbers, 68, New Road, Hethersett. Wildlife 2000 Committee: R.Hancy (Chairman), S.Livermore (Secretary) 6, Terence Ave, Sprowston, Norwich NR7 8EH Elected Members of Council: D.Howlett, S.Livermore, F.J.Farrow, Dr I. F.Keymer, R.Maidstone, K.Rivett, A.P.Scowen, G.M.Coupland, R.W. Ellis, Mrs J.Negal, C.W. Penny, Miss E.M. Phipps Co-opted Members: Dr A.G. Irwin (Museum), Dr W. Sutherland (University), B.Joyce (Norfolk Wildlife Trust), P.W.Lambley (English Nature) THE NATURAL HISTORY MUSEUM ? 26 JUL 1P97 EXCHANGED Wildlife 2000 GENERAL LIBRARY During its 125th anniversary celebrations, the Norfolk and Norwich Naturalists' Society announced its intention to document the wildlife of Norfolk for the start of the new millenium in a project called Wildlife 2000. In practical terms the project was launched in May 1995 when representatives of the Society, English Nature, Norfolk Wildlife Trust and the Castle Museum met and agreed to share this common vision. Sir Thomas Browne has given us a fascinating glimpse of seventeenth century wildlife in the County of Norfolk. He writes of bustards, storks, ravens and kites; salmon and otters; and the mole cricket which he describes as common in "fenny places.... and dunghills and churchyards in this citty." Nineteenth century records of the mole cricket from Castle Acre and Stoke Holy Cross suggest a lingering presence for this species in river flood plains across the county, but we are left tantalisingly ignorant of its historic distribution. How widespread was it, how abundant where it did exist, and until how recently did it survive? Wildlife 2000 is a project designed to ensure that twenty first century naturalists will have the answers to the equivalent questions they might ask about our flora and fauna, as they approach the end of their own century. Wildlife 2000 seeks to create a "time capsule" which will preserve our knowledge of the countryside, and what could be found in it at the start of the third millenium. The project is not just concerned with nature reserves and rare species, but seeks to give an accurate account of the wider countryside and the commoner species which abound within it. Just as the mole cricket was common in Thomas Browne's day but is now lost, so any other creature or plant which we take for granted could become rare or extinct over the next century. By documenting the wildlife heritage which we pass into the care of the twenty first century, those who come after us may be in a better position to preserve and protect that legacy. In this issue of the Transactions of the Norfolk and Norwich Naturalists' Society three papers reflect the aims of the Wildlife 2000 project. Lindsay Moore provides an overview of the flora of chalk grasslands in Norfolk and links this with detailed descriptions of all the calcareous sites in the County. Calcareous grasslands are under threat both nationally and internationally and the paper highlights the need for protection and appropriate management. Dick Hamond changes the focus from habitats and communities to look closely at three small groups of entomostracan Crustacea within the Norfolk area. He describes seventeen species with notes on their Norfolk distributions. Phil Withers observes that there are many groups of insects which, although widespread, are unpopular and tend to be ignored by most naturalists. The British fauna of free-living bark-lice is slightly in excess of 50 species and he records 26 of these from Norfolk. WILDLIFE 2000 Publications Trans. Norfolk and Norwich Nats. Soc. 1997; 31(1) Chalk grassland in Norfolk Lindsay Moore 1-30 The Cirripedia, Branchiura & Cladocera of Norfolk R. Hamond 52-62 The free-living bark-lice (Insecta; Psocoptera) of Norfolk P. Withers 87-94 WILDLIFE 2000 CHALK GRASSLAND IN NORFOLK Lindsay Moore English Nature 60 Bracondale Norwich NR1 2BE Introduction This paper is based on a survey of the calcareous grasslands in East Anglia undertaken by the author in 1991 and set out in a report (Moore 1993). Calcareous grasslands are under threat both nationally and on the continent, so the focus of the survey was to determine whether this habitat type was receiving adequate legal protection within the Sites of Special Scientific Interest (SSSI) series. This involved the survey of all known calcareous grasslands above a minimum qualifying size (0.3 ha), according to the National Vegetation Classification (NVC) as described in Rodwell (1994). The survey identified the different calcareous grassland community and sub-community types present. Certain of these types, due to their floristic richness and or scarcity of occurrence, qualify a grassland for SSSI status. The work highlighted the presence of such ‘notifiable’ communities and in some cases the need for protection and/or appropriate management. This paper summarises the reports findings relevant to Norfolk and discusses the distribution of calcareous grassland in relation to natural and man-made features both ancient and more recent. Histoiy Although chalk underlies about fifty percent of the County, the drift cover means that chalk is rarely close to the surface. This has restricted the development of calcareous grasslands to small areas. In addition, the subdued relief has rarely imposed any constraint to ploughing (unlike the chalk downlands of southern England where the scarp faces have been too steep to plough) and this has reduced the area of chalk flora still further. Loss of calcareous grassland has probably been taking place since the Trans. Norfolk Norwich Nat.Soc. 1997 31 0) 1 enclosures in the late eighteenth and early nineteenth centuries when extensive areas of sheep walk were enclosed. The losses of the last fifty years have been well documented in the Flora of Norfolk (Petch and Swann 1968) and can be attributed to afforestation, agricultural reclamation, lack of grazing and waste disposal in old quarries and cuttings. The reduction in rabbit numbers since the onset of myxomatosis in 1953 and subsequent outbreaks has been particularly damaging to sites no longer grazed by livestock. This probably explains the decline of interesting grasslands at Devils Ditch, Cranwich, and at Devils Ditch, Garboldisham. Examples of chalk-loving vascular plants lost from the Norfolk flora in the last fifty years include Bastard Toadflax (Thesium humifusum) and Spring Cinqefoil (Potentilla tabemaemontani), whilst others such as Spiked Speedwell (Veronica spicata) and Autumn Lady's-tresses (Spiranthes autumnalis ) have been reduced in distribution. Distribution Calcareous grassland survives in two main areas; the Breckland and the north-west of the county, with a few scattered outliers elsewhere. It can be found associated with a range of natural topographical features such as river cliffs (eg Cockthorpe Common) and pingos (eg East Walton and Adcock's Commons). In Breckland, soil patterning is also very important in determining the presence or absence of chalk vegetation. Unimproved chalk grassland also occurs on man-made earthworks where the chalk has been brought to the surface or exposed during construction. These include ancient historical sites such as flint mines (eg Grimes Graves), forts (Warham Camp), linear banks (Bichamditch) and castle mounds (eg Castle Acre). More recent works include railway lines, quarries (Wells Chalkpit) and those caused by military activities such as camp bases (Cranwich Camp) and bomb craters. Types of Chalk grassland and associated vegetation communities The following chalk grassland communities described in the National Vegetation Classification by Rodwell have been found during the survey in Norfolk. Trans. Norfolk Norwich Nat.Soc. 1997 31 0) 2 CG2 Sheep fescue-Meadow Oat-grass ( Festuca ovina-A venula pratensis ) grassland. This is defined as true chalk grassland. It is rare in Norfolk due to drift cover. There are a number of sub-communities distinguished of which the following two occur in Norfolk: the CG2a Dwarf Thistle-Squinancywort ( Cirsium acaule-A sperula cynanchica) sub-community, Dropwort-Common Rock-rose (Filipendula vulgaris-Helianthemum nummularium variant.) and the CG2c Yorkshire Fog- White Clover (Holcus lanatus -Trifolium repens ) sub-community The CG2 community is characterised by the presence of Meadow Oat -grass {A venula pratensis), Quaking Grass (Briza media), Glaucous Sedge (Carex flacca), Sheep's Fescue (Festuca ovina), Mouse-eared Hawkweed (Hieracium pilosella), Crested Hair-grass (Koeleria macrantha), Rough Hawkbit (Leontodon hispidus), Fairy Flax (Linum catharticum), Bird's-foot Trefoil (Lotus comiculatus), Ribwort Plantain (Plantago lanceolata), Salad Burnet (Sanguisorba minor), Small Scabious (Scabiosa columbaria) and Thyme (Thymus praecox). CG6 Downy Oat-grass (A venula pubescens ) grassland. This is very rare in Norfolk and only the CG6a Cock'sfoot-Quaking Grass (Dactylis glomerata -Briza media) sub-community was found. The CG6 community is characterised by the presence of Meadow Oat -grass (A venula pratensis), Downy Oat-grass (A.