Upland Oakwood (Uk Bap Priority Habitat)

UPLAND OAKWOOD (UK BAP PRIORITY HABITAT) Summary This is woodland on well-drained to rather poorly drained, acidic to neutral soils in the upland parts of Britain, where either pedunculate or sessile oak forms at least 30% of the canopy cover. Other tree and shrub species occur commonly, especially downy birch, silver birch, rowan, hazel and holly. Like upland birchwoods, the field layer is mostly grassy or heathy, but when very heavily grazed can be dominated by large bryophytes. Small herbs, bryophytes and ferns, including bracken, can be very common, and on rocks, banks, trees and shrubs in the west there can be a rich flora of oceanic bryophytes including some uncommon species. Most Scottish examples of this priority habitat are on moderate to steep slopes below 300 m, with well drained brown earth or podzol soils. This priority habitat can occur in mosaics with the Upland birchwoods, Upland mixed ashwoods and Wet woodland priority habitats, as well as with open habitats including bracken, heath, cliffs, screes and acid grassland. The habitat is widespread in Scotland and in upland areas of Britain generally. Good management for conservation in this habitat generally aims towards maintaining a good diversity of species, sizes and age classes of trees and shrubs, encouraging diversity in the structure and species composition of the ground vegetation, maintaining rich bryophyte and lichen assemblages on rocks and trees especially in the west, maintaining good quantities of standing and fallen dead wood, and controlling the extent and spread of non-native trees and shrubs, especially rhododendron, Rhododendron ponticum. What is it? This is woodland on well-drained to rather poorly drained, acidic to neutral soils in the upland parts of Britain, where sessile oak Quercus petraea or pedunculate oak Quercus robur forms at least 30% of the canopy cover. Other tree and shrub species occur commonly, especially silver birch Betula pendula, downy birch Betula pubescens, rowan Sorbus aucuparia, hazel Corylus avellana and holly Ilex aquifolium. Most of the Upland oakwood has a field layer which is grassy or heathy. In grassy examples typical species include wavy hair-grass Deschampsia flexuosa, common bent Agrostis capillaris, sweet vernal-grass Anthoxanthum odoratum, tormentil Potentilla erecta and heath bedstraw Galium saxatile. In heathy examples these species can also occur in small quantity but in a sward of ling Calluna vulgaris, bilberry Vaccinium myrtillus or, on some south-facing slopes, bell heather Erica cinerea. The heathy examples are generally on strongly acid soils but moderate to heavy grazing in such places can lead to grassier – or even bryophyte dominated – field layers. On more mildly acid soils the ground flora is less heathy and small herbs are more common including wood sorrel Oxalis acetosella, common dog-violet Viola riviniana and primrose Primula vulgaris. In the damper examples of this priority habitat purple moor-grass Molinia caerulea can be abundant or dominant in the field layer. Bryophytes and ferns are generally common throughout. Typical bryophytes include the mosses Hylocomium splendens, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus loreus, R. triquetrus, R. squarrosus, Dicranum majus, D. scoparium, Polytrichastrum formosum and Leucobryum glaucum. Bryophytes are especially plentiful and diverse on the thinner, more acidic soils. Ferns typically include hard fern Blechnum spicant, Dryopteris spp. and bracken Pteridium aquilinum: this last species can be dominant in the field layer on deep brown earth soils. Much of this woodland is on steep slopes where the ground vegetation is broken by rock outcrops and boulders. These rocks generally support an abundance of bryophytes and in some places lichens. Their bryophyte floras are especially luxuriant and varied in the wetter west, where they include several western species such as the mosses Dicranum scottianum and Sematophyllum micans and the liverworts Scapania gracilis, Plagiochila spinulosa, P. atlantica, P. bifaria, P. punctata, Saccogyna viticulosa, Bazzania trilobata, Adelanthus decipiens, Aphanolejeunea microscopica, Drepanolejeunea hamatifolia and Harpalejeunea molleri. The western filmy ferns Wilson’s filmy-fern Hymenophyllum wilsonii and Tunbridge filmy-fern H. tunbrigense, which are small ferns looking more like bryophytes at first glance, also grow in these habitats. The epiphytic floras on oaks and other trees in this priority habitat, especially in the west, can be rich in bryophytes including most of the western species listed above. Lichens of the Lobarion community are a particular characteristic of western woodlands, including large foliose species such as Lobaria pulmonaria, L. scrobiculata, L. virens, L. amplissima, Sticta sylvatica, S. uliginosa, S. limbata, Nephroma laevigatum and Pseudocyphellaria spp. Species of more acid bark, such as Menegazzia terebrata and Hypotrachyna taylorensis, are also often present, along with the many smaller crustose species of the Graphidion community. These communities are better developed in Scotland than anywhere else in Europe. Scottish examples of this priority habitat have much in common with those in the rest of the UK, but compared with those in England and Wales they do not generally extend to such a high altitude and tend to have less bramble and honeysuckle. How do I recognise it? Differentiation from other Priority Habitats Upland birchwoods are the most similar to the Upland oakwood priority habitat in terms of their habitat and ground vegetation, but they have a canopy including abundant to dominant birch and with little or no oak, and are restricted to the Scottish Highlands and Hebridean islands. Stands of birch further south are best regarded as cyclical or successional stages of other types of woodland, especially that belonging to the Upland oakwood priority habitat. Lowland mixed deciduous woodland can have similar ground vegetation and an oak- dominated canopy, but generally much less rich communities of lichens and bryophytes. They generally comprise different NVC types. The only NVC overlap between these two priority habitats is the W16 community: stands of W16 containing oak are treated as Lowland mixed deciduous woodland where they occur in the lowlands but as Upland oakwood where they occur on the upland fringes. The NVC separates Upland mixed ashwoods (W9 and certain examples of W7 and W8) from Upland oakwood which does not include W7-9. The Upland oakwood and Wet woodland priority habitats are largely separable by NVC type, but the W4 community occurs in both. The W4c sub-community is restricted to Wet woodland. The drier W4a sub-community occurs in the Upland oakwood and Upland birchwoods habitats but not in the Wet woodland habitat. In previously published priority habitat definitions, some of the less wet examples of W4b and those which are in mosaics with drier W10e, W11, W16 and W17 woodland are considered to be best placed in the Upland birchwoods or Upland oakwood priority habitats, depending on location and canopy as described above. However, typical W4b is as wet as many other NVC communities in the Wet woodland priority habitat and is clearly different from the drier W10, W11 and W17 communities: this might suggest keeping it within the Wet woodland habitat. Using patch size as a guide is a useful approach such that a small area of W4b within a larger area of W11 would classify as Upland birchwood; whereas if the W4b is largely associated with W4c then it would classify as Wet woodland. Definition in relation to other habitat classifications Classification Habitat types belonging to this UK BAP priority habitat All examples of W4a, W10e, W11 and W17 in which oak forms >30% of the canopy cover. Upland fringe examples of W16 in which oak forms >30% of the canopy cover. NVC Examples of non-NVC ‘WLz’ (with very species-poor Luzula sylvatica ground vegetation) in upland or upland fringe situations, in which oak forms >30% of the canopy cover. (All of the above NVC communities are included in the Scottish Biodiversity List.) A1: oakwood examples of W4a, W10e, W11, W17 and WLz with oak >30% of canopy cover; total canopy cover >30% Phase 1 A2: oak scrub forms of W4a, W10e, W11, W17 and WLz with oak >30% of canopy cover A3: oakwood examples of W4a, W10e, W11, W17 and WLz with oak >30% of canopy cover; total canopy cover <30% A4: recently felled W4a, W10e, W11, W17 and WLz oakwood with oak >30% of canopy cover UK BAP broad All examples of this priority habitat belong to the broad habitat - habitat Broadleaved, mixed and yew woodland NVC communities W11 and W17 account for most of the Upland oakwood in Scotland. The sub-communities W8e/f/g and W10e, and examples of W16 and W8d in the upland fringe, have historically been assigned to Upland priority woodland habitats. However, W8, W10 and W16 are generally lowland communities, and their flora and distribution reflect the influence of a warmer and/or drier lowland climate compared with that of their upland counterparts W9, W11 and W17. It may be preferable to consider all examples of W8/10/16 woodland in lowland Scotland as part of the Lowland Mixed Deciduous woodland habitat. The Native Woodland Survey of Scotland classified woodland to community level only, and included all examples of W8, W10 and W16 within the Lowland mixed deciduous woodland priority habitat. Definition in relation to legislative classifications Classification Habitat types belonging to this UK BAP priority habitat Habitats H91A0 (all occurrences). Directive Annex I SNH SSSI All examples of the Upland oakwood priority habitat belong within habitat features the Upland oak woodland SSSI feature type. Where is it? Most Scottish examples of this priority habitat are on moderate to steep slopes with well drained brown earth or podzol soils. Within larger areas of woodland this priority habitat can occur in mosaics with the Upland birchwoods priority habitat, more flushed areas with the Upland mixed ashwoods priority habitat or wetter areas with the Wet woodland priority habitat.

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