Nettlebed Common Plant Report J A Webb June 2015 Nettlebed Common Plant Survey Report Dr Judith A Webb Ecological Consultant 2 Dorchester Court Blenheim Road Kidlington Oxon OX5 2JT Website: http://judithwebb.weebly.com/ June 2015 Pond area at Nettlebed Common on 29th May 2015, some tree removal already has taken place and ground flora regrowth is apparent. Introduction I was requested to survey plants in parts of Nettlebed Common adjacent to a series of shallow pools (some ex-clay pits) mainly to the south and east of Mill House. The aim of this survey was to gain a picture of the vascular plant flora to complement the bryophyte survey already undertaken. Any interesting, scarce or rare plants found could then be preserved in any remedial scrub/ tree or pond work. This work is an initiative of the Nettlebed and District Commons Conservators, with funding for the preliminary site surveys from the Chilterns Commons Project overseen by Rachel Sanderson. 1 Nettlebed Common Plant Report J A Webb June 2015 Spring and early summer are appropriate times for such a survey as most plants have produced leaves enabling identification, and flowers are needed for identification of some early species such as violets. All photographs in this report are my own. Methods The site was visited on 15.04.2015 and 01.05.2015 for early flowering species and on 29.05.2015 for later flowering species. About 2 hours was spent surveying each time and the designated area was thoroughly searched. The centre of the area searched was more or less SU 703 871. Results In this acid area the range of vascular plants and pteridophytes was not expected to be large. A total of 79 species were found altogether. The list of species recorded is to be found in the Appendix. The most noticeable and frequent plants in the area are trees such as grey willow Salix cinerea, silver birch Betula pendula and crack willow Salix fragilis. Less frequent woody species include peduculate oak Quercus robor, ash Fraxinus excelsior, common hawthorn Crataegus monogyna, rowan Sorbus aucuparia, blackthorn Prunus spinosa, sycamore Acer pseudoplatanus and dogwood Cornus sanguinea. One Scot’s pine Pinus sylvestris is in the middle of the area with a young beech Fagus sylvatica and a few individual bushes of holly Ilex aquifolium. Aspen Populus tremula trees and suckers are frequent on the margin of one area. Gorse Ulex europaea bushes are rare. Both dog rose Rosa canina agg. and field rose Rosa arvensis are present in small quantity. Ferns include frequent bracken Pteridium aquilinum, occasional broad buckler fern and male fern including the occasional much less common species known as scaly male fern Dryopteris affinis. Scaly male fern Dryopteris affinis, 1st May 2015 Scrub present comprised mall amounts of bramble Rubus fruticosus and dewberry Rubus cesius. Some patches of redcurrant Ribes rubrum, black currant Ribes nigrum and gooseberry Ribes uva-crispa are likely to be garden escapes and should possibly be targeted for removal. 2 Nettlebed Common Plant Report J A Webb June 2015 Ground flora of the drier mounds is dominated by native bluebell Hyacinthoides non-scripta which can form single species carpets, with smaller quantities of violets such as early dog violet Viola reichenbachiana Wetland plants around the shallow pools were such species as mats of the grass brown bent Agrostis canina, lesser spearwort Ranunculus flammula, marsh bedstraw Galium palustre, wavy bitter-cress Cardamine flexuosa, compact rush Juncus conglomeratus, marsh thistle Cirsium palustre. Areas where trees had already been felled sometimes showed extensive growths of creeping soft grass Holcus mollis. A jointed rush Juncus acutiflorus/articulatus is present in the pools but could not be determined as only young flowers and no fruits were present at the time of the visits. A good range of sedges were found including remote sedge Carex remota, wood sedge Carex sylvatica, common or black sedge Carex nigra, locally dominant stands of pendulous sedge Carex pendula and small quantities of pill sedge Carex pilulifera and a yellow sedge Carex cf demissa. All yellow sedge species are now on the Oxon Rare Plants Register. A clump of a yellow sedge, likely to be Carex demissa, flowering in newly cleared area on 29th May 2015. The designated area had rare patches of wood sorrel Oxalis acetosella, foxglove Digitalis purpurea and slender St John’s Wort Hypericum pulchrum; this last being a rather local/scarce species (Killick et al. 1998) yet it is fairly common in this area and is expected to benefit from the increased light levels occasioned by this work. Tutsan Hypericum androsaemum is found in small amounts in the area. This is on the county Rare Plants Register, but is a lot more frequent in the Chilterns than the rest of the county. It too would benefit from increased light levels. During the future works pendulous sedge Carex pendula is recommended for removal. This is an invasive and dominant sedge which will thrive in the increased light and will therefore shade out smaller, more desirable plants plus create cold conditions in the wetland which will be less advantageous to certain 3 Nettlebed Common Plant Report J A Webb June 2015 invertebrates. It is particularly important it not be allowed to spread and shade the valuable Sphagnum lawns (S. auriculatum and S. denticulatum) identified in my previous bryophyte survey of this area. Bulbous rush Juncus bulbosus is on the Rare Plants Register for Oxfordshire, but is occasional in the acid area of the Chilterns commons in shallow pools or wet hollows. A small quantity was found. The proposed works are expected to benefit this species as it needs higher light levels than there are at present. Conclusions Most vascular plants found were very common, but there were a couple of species that are scarce to rare in the county and in the case of dry land plants the same ones that were frequent in the surrounding areas which will not be targeted in the remedial scrub, tree and pond work. In fact the following beneficial effects of remedial work around these ponds on the flora are expected to be; • Higher light levels will benefit the populations of wetland plants that have been struggling in the shade of the willow scrub around some ponds. Examples are lesser spearwort and marsh bedstraw • Slight raising of the water level in some pools will be to the advantage of wetland species dependent on light such as water starwort Callitriche sp. and bulbous rush • Soil disturbance and higher light levels on drier ground will allow germination of seed bank species such as foxglove Reference Killick, J., Perry, R. and Woodell, S., (1998) The Flora of Oxfordshire, Pisces Publications Acknowledgements I thank R. d’Ayala for pointing out the limits of the exact area to be surveyed as this will be the target for remedial tree work. 4 Nettlebed Common Plant Report J A Webb June 2015 Appendix: List of Vascular Plant Species on Nettlebed Common in area of scheduled works (interesting species highlighted) Nettlebed Common Ponds centre SU 703 Area J A Webb 871 Scientific name common name group Date abundance comment Acer pseudoplatanus sycamore flowering plant 15.04.2015 O Agrostis canina brown bent flowering plant 29.05.2015 F Anthoxanthum odoratum sweet vernal grass flowering plant 29.05.2015 F Arctium sp burdock flowering plant 15.04.2015 O Arum maculatum cuckoo-pint flowering plant 15.04.2015 O Betula pendula silver birch flowering plant 15.04.2015 F Brachypodium sylvaticum false-brome flowering plant 15.04.2015 O Callitriche sp.cf. brutia pedunculate water-starwort flowering plant 15.04.2015 O Cardamine flexuosa wavy bitter-cress flowering plant 15.04.2015 O Carex nigra common or black sedge flowering plant 29.05.2015 O Carex ovalis oval sedge flowering plant 29.05.2015 O Carex pendula pendulous sedge flowering plant 15.04.2015 LF Carex pilulifera pill sedge flowering plant 29.05.2015 O Carex remota remote sedge flowering plant 15.04.2015 O Carex sp cf demissa common yellow sedge flowering plant 29.05.2015 R mature fruits needed Carex sylvatica wood sedge flowering plant 15.04.2015 LF Cirsium palustre marsh thistle flowering plant 15.04.2015 O Cornus sanguinea dogwood flowering plant 15.04.2015 O Corylus avellana hazel flowering plant 15.04.2015 LF Crataegus monogyna common hawthorn flowering plant 15.04.2015 O Deschampsia cespitosa tufted hair grass flowering plant 15.04.2015 O Deschampsia flexuosa wavy hair grass flowering plant 29.05.2015 O Digitalis purpurea foxglove flowering plant 15.04.2015 O Dryopteris affinis scaly male fern fern 15.04.2015 O Dryopteris dilatata broad buckler-fern fern 15.04.2015 O Dryopteris filix mas male fern fern 15.04.2015 O Epilobium hirsutum great willow-herb flowering plant 15.04.2015 LF Equisetum palustre marsh horsetail horsetail 29.05.2015 O Fagus sylvatica beech flowering plant 15.04.2015 R 1 young tree Festuca gigantea giant fescue flowering plant 29.05.2015 R Ficaria verna lesser celandine flowering plant 15.04.2015 O Fraxinus excelsior ash flowering plant 15.04.2015 O Galium palustre marsh bedstraw flowering plant 15.04.2015 F Geranium robertianum herb robert flowering plant 15.04.2015 O Glechoma hederacea ground ivy flowering plant 15.04.2015 O Glyceria fluitans floating sweet grass flowering plant 15.04.2015 R Holcus lanatus yorkshire fog flowering plant 29.05.2015 O Holcus mollis creeping soft grass flowering plant 29.05.2015 LF Hyacinthoides non-scripta bluebell flowering plant 15.04.2015 LF Hypericum androsaemum tutsan flowering plant 15.04.2015