National Vegetation Classification survey for Drone Moss Site of Special Scientific Interest (SSSI)

Transcription

1 COMMISSIONED REPORT Commissioned Report No. 131 National Vegetation Classification survey for Drone Moss Site of Special Scientific Interest (SSSI) (ROAME No. F03LJ08) For further information on this report please contact: Sarah Eno Scottish Natural Heritage Anderson s Chambers GALASHIELS TD1 3AF Telephone: sarah.eno@snh.gov.uk This report should be quoted as: Central Environmental Surveys (2006). National Vegetation Classification survey for Drone Moss Site of Special Scientific Interest (SSSI). Scottish Natural Heritage Commissioned Report No. 131 (ROAME No. F03LJ08). This report, or any part of it, should not be reproduced without the permission of Scottish Natural Heritage. This permission will not be withheld unreasonably. The views expressed by the author(s) of this report should not be taken as the views and policies of Scottish Natural Heritage. Scottish Natural Heritage 2006

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3 COMMISSIONED REPORT Summary National Vegetation Classification survey for Drone Moss Site of Special Scientific Interest (SSSI) Commissioned Report No. 131 (ROAME No. F03LJ08) Contractor: Central Environmental Surveys Year of publication: 2006 Background Drone Moss is a small basin mire in Berwickshire covering 23.5ha. The topography of the mire conforms to the raised dome shape with woodland in the lagg zone around the edge. Main findings The body of the mire was Erica tetralix Sphagnum papillosum raised mire but often the structure and species composition bore little resemblance to this community. The mire was very heathy and dry but the drying out was not leading to the Empetrum nigrum Cladonia sub-community but more towards the appearance of a dry heath or drier bog community. This drying out was more prevalent in the centre of the dome where the tall Calluna and occasional Eriophorum vaginatum tussock with pleurocarpous mosses gave the impression of Calluna vulgaris Eriophorum vaginatum blanket mire. More typically wetter stands could be seen around the edge of the dome before the woodland canopy began. Invading Rhododendron sp. is beginning to colonise the mire surface around the edge together with colonising Betula pubescens. The woodland was of two types. The first was along the eastern edge which was Salix pentandra Carex rostrata woodland. This woodland was very wet with pools of standing water within the woodland. The even-topped canopy of Betula pubescens or Salix caprea, together with the large stands of Juncus acutiflorus and Carex rostrata distinguished this woodland type from the neighbouring drier woodland. The remaining woodland was the Betula pubescens Molinia caerulea woodland. Most of this was the Dryopteris dilatata Rubus fruticosus sub-community. For further information on this project contact: Sarah Eno, Scottish Natural Heritage, Anderson s Chambers, Galashiels TD1 3AF Tel: For further information on the SNH Research & Technical Support Programme contact: The Advisory Services Co-ordination Group, Scottish Natural Heritage, 2 Anderson Place, Edinburgh EH6 5NP Tel: or ascg@snh.gov.uk

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5 Contents Summary 1 NVC DESCRIPTIONS Woodlands W3 Salix pentandra Carex rostrata woodland W4 Betula pubescens Molinia caerulea woodland W4a Dryopteris dilatata Rubus fruticosus sub-community Mires M18 Erica tetralix Sphagnum papillosum raised mire M18a Sphagnum magellanicum Andromeda polifolia sub-community 2 2 TARGET NOTES 3 3 MANAGEMENT 4 Appendix 1 Drone Moss quadrat data 5 Appendix 2 Drone Moss map 9

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7 1 NVC DESCRIPTIONS 1.1 Woodlands W3 Salix pentandra Carex rostrata woodland The canopy was either stands of pure Betula pubescens or Salix caprea. There was little structural stratification of the woody species, just an even, low canopy. The ground was extremely wet, to the point that when the trees were swaying in the wind, the movement of the root plates could be felt beneath the feet. Stands of Carex rostrata and Juncus acutiflorus gave most of the character to this woodland. Within these there were several poor-fen associates such as Succisa pratensis, Valeriana officinalis, Viola palustris, Senecio aquatica, Rumex acetosa, Equisetum fluviatile and Potentilla palustris, although they were not frequent. Smaller herbs such as Ranunculus repens and Cardamine pratensis were also present and infrequent. Galium palustre was the most common herb, but was patchy in its vigour and abundance. The wetness of the terrain made some areas too difficult to get to, but generally the bryophyte layer was very patchy with Sphagnum palustre and S. squarrosus in the wetter areas. Other than this, there was a little Polytrichum formosum and Mnium hornum. It was felt that the areas dominated by rushes were probably more recent and reflect the precursor vegetation found at the very edge which was the Juncus effusus/acutiflorus Galium palustre rush pasture. Time may see the replacement of the rushes with large sedge species W4 Betula pubescens Molinia caerulea woodland W4a Dryopteris dilatata Rubus fruticosus sub-community The canopy was very similar to the former community with Salix cinerea and Betula pubescens dominating, usually in discrete stands but with a bit more mixing. Additionally, the odd Sorbus aucuparia added some diversity. Structurally, the woodland was again virtually one-tiered, but some scrambling Lonicera periclymenum occasionally reached up into the canopy. Molinia was patchy in its abundance but Dryopteris dilatata was abundant virtually throughout. Rubus fruticosus was frequent but not structurally prominent. The density of the field-layer often shaded any bryophytes beneath. Mnium hornum and Eurynchium praelongum were the most frequent. A small area of woodland was seen in the south-east near the caravan park. This has been recorded as this community but it was much drier and had dense stands of bracken within and around it. It was here that a single plant of Trientalis europaea was found. The birch here also included individuals of Betula pendula and undoubtedly there will be hybrids. This small area had the appearance of the Quercus petraea Betula pubescens Oxalis acetosella woodland, but its small area and position on the edge of a moss has lead to its inclusion within the Betula pubescens Molinia caerulea as a local variation. Within the general background of this community, there were wetter areas that were taken to be other sub-communities. In wet channels, Juncus effusus was dominant as in the Juncus effusus sub-community. There were a few small hollows where Sphagnum squarrosum in particular was abundant and where the mire was being colonised by trees so that many of the mire characteristics were still evident. These areas were recorded as the Sphagnum sub-community. 1

8 1.2 Mires M18 Erica tetralix Sphagnum papillosum raised mire M18a Sphagnum magellanicum Andromeda polifolia sub-community This community formed the dome of the raised mire, but its floristic composition varied over the dome. Its usual form was seen around the lower areas, such as in shallow depressions and around the edge of the mire. Here the Sphagnum layer supported S. magellanicum, S. capillifolium, S. papillosum and S. subnitens. In these wetter areas Eriophorum vaginatum was prominent and species such as Narthecium ossifragum and Vaccinium oxycoccos could be found. There were wet depressions in the mire that looked as if they had at one time been bog-pools, but now supported the Erica tetralix Sphagnum papillosum raised mire community. Moving away from these areas the Sphagnum layer becomes patchy and species such as S. magellanicum and S. papillosum are lost and S. capillifolium and S. subnitens become occasional at most. Eriophorum vaginatum still persists in these drier areas and the Calluna becomes tall and heathy. Empetrum nigrum and Erica tetralix are occasional throughout but only as sparse sprigs. Beneath this there is a clear shift from Sphagnum spp. towards pleurocarpous mosses such as Hypnum and Pleurozium schreberi. 2

9 2 TARGET NOTES Grid reference NT NT NT NT Target note Ex bog pools about 1m diameter. Abundant V. oxycoccos, also Drosera rotundifolia. Transition to bog. M18 with 70% canopy cover. Pond on edge or just out of SSSI. Large Carex sp. Couldn t get close enough to sample. Salix repens and Trientalis europaea in wood nearby. Bog here is poor and dry. Little M18 character. Even E. vaginatum sparse. 3

10 3 MANAGEMENT The heathy condition of the heather implies that grazing pressure here is low. Sheep droppings were found however, and there were signs of hard grazing within the woodland to the north east. Dead stools of what was assumed to be Molinia tussocks (or possibly even Carex paniculata) were found completely grazed off. It was assumed that the occasional run-away sheep was responsible. The drying out of the bog was considered as arising from natural succession being accelerated by loss of water through the surrounding drains. The surrounding landuse is agricultural with some heath to the North. No drains were seen over the bog surface, so peripheral drainage is the key issue here. Another issue, more readily addressed is the invasion of Rhododendron bushes. These have a hold in the drier woodland on the site and are steadily seeding and invading in towards the centre of the dome. Hand-pulling of the seedlings is still possible, but ultimately the larger specimens need to be taken out to remove the seed-source. 4

11 Appendix 1 Drone Moss quadrat data M18a Species QP06 QP07 QP08 QP09 QP10 QP11 QP12 QP13 Summary Calluna vulgaris V(7 9) Erica tetralix V(1 4) Eriophorum angustifolium I(3) Eriophorum vaginatum V(3 7) Sphagnum capillifolium IV(3 8) Sphagnum magellanicum II(4 6) Narthecium ossifragum I(4) Vaccinium oxycoccos I(6) Pleurozium schreberi I(7) Aulacomnium palustre II(2 6) Hypnum cupressiforme IV(4 8) Sphagnum palustre I(8) Empetrum nigrum III(2 5) 5

12 W3 Species QP16 QP17 QP18 QP19 Summary Salix cinerea V(6 8) Betula pubescens III(3 5) Carex rostrata V(3 8) Galium palustre IV(4 6) Juncus effusus IV(2 6) Sphagnum squarrosum IV(4 6) Viola palustris IV(1 3) Sphagnum palustre III(6) Holcus lanatus III(3 4) Potentilla erecta III(2 4) Juncus acutiflorus II(5) Agrostis canina II(3) Polytrichum formosum II(3) Potentilla palustris II(3) Rumex acetosa II(3) Succisa pratensis II(3) Agrostis capillaris II(2) Ajuga reptans II(2) Dryopteris dilatata II(2) Equisetum fluviatile II(2) Myosotis scorpoides II(2) Ranunculus flammula II(2) Ranunculus repens II(2) Senecio aquatica II(2) Angelica sylvestris II(1) Cardamine pratensis II(1) 6

13 W4a Species QP01 QP02 QP03 QP04 QP05 Summary Betula pubescens V(6 8) Salix cinerea III(1 6) Salix aurita I(6) Rubus fruticosus agg III(2 4) Rhododendron sp I(2) Dryopteris dilatata V(5 8) Molinia caerulea V(3 6) Mnium hornum IV(2 6) Eurynchium praelongum III(2 6) Potentilla erecta III(1 2) Holcus lanatus II(4) Agrostis canina II(3) Carex nigra II(2) Eriophorum vaginatum I(5) Sphagnum palustre I(5) Plagiothecium undulatum I(3) Deschampsia cespitosa I(2) Lonicera periclymenum I(2) Lophocolea bidentata I(2) Rubus fruticosus agg I(2) Eriophorum angustifolium I(1) 7

14 W4_W11 Species QP21 Betula pubescens 7 Betula pendula 4 Salix aurita 3 Salix cinerea 1 Rhododendron sp 3 Rubus fruticosus agg. 2 Dryopteris dilatata 6 Eurynchium praelongum 6 Mnium hornum 5 Agrostis canina 2 Holcus lanatus 2 Luzula pilosa 2 Pteridium aquilinum 2 Urtica dioica 2 Geum urbanum 1 Trientalis europaea 1 8

15 Appendix 2 Drone Moss These maps are based upon the Ordnance Survey material with the permission of Ordnance Survey on behalf of the Controller of Her Majesty s Stationery Office Crown copyright (2006). Any unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Scottish Natural Heritage (2006). 9