Plant communities found in surveys by ben and alison averis but not described in the uk national vegetation classification




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PLANT COMMUNITIES FOUND IN SURVEYS BY BEN AND ALISON AVERIS BUT NOT DESCRIBED IN THE UK NATIONAL VEGETATION CLASSIFICATION
Ben and Alison Averis

January 2015

These short summary descriptions are presented here to help people working with vegetation surveys and the UK National Vegetation Classification (NVC) (Rodwell 1991 et seq.). They describe vegetation types which we have seen during our surveys but which are not included in the NVC or which can be classed as particular distinctive forms of existing NVC communities or sub-communities. The descriptions that follow are based on our own observations except where acknowledged.


Also included here are a few vegetation types which are floristically intermediate between two NVC communities. NVC intermediates are so numerous and so common that an attempt to describe all of them would cause great complexity and confusion. They can often be recognized fairly easily anyway, and classified as such (for example U4-U5 or M15a-c). However, a few NVC intermediates are included here because they are particularly common, extensive or distinctive. Vegetation types restricted to extremely narrow or linear strips such as that between a roadside verge and the base of an adjacent hedge or wall are not included. There is something of a northern/upland bias to the vegetation types described here. This is because most of our survey work has been in northern and upland areas.
The vegetation types are ordered into broad groupings: Woodland and scrub; Heaths; Bogs; Rush-dominated vegetation; Other wetlands; Grasslands; Fern-dominated vegetation; Montane summit/snowbed habitats; Coastal vegetation; Other habitats.
NVC codes are referred to wherever relevant; a list of the codes and names of all NVC communities is given at the end of this document, and where sub-communities are mentioned in the text, their names are given. For the purpose of vegetation survey maps and associated reports, made-up ‘non-NVC’ codes and names can be used for communities without official published codes and names; some codes we have used are mentioned in this document.
Many of the vegetation types described here are also included along with additional ‘non-NVC’ vegetation types (found by other people and not seen by us) in the Review of coverage of the National Vegetation Classification (Rodwell et al. 2000).
We hope this document will be of use to vegetation surveyors and other people with an interest in British vegetation. Any feedback will be welcome. A revised version will be produced and made available if and when appropriate.

CONTENTS

WOODLAND AND SCRUB – PAGE 1

Salix aurita scrub with a W4-type flora, on damp to wet acid soils

Salix aurita scrub with a W7-type flora, on damp to wet neutral soils

Salix cinerea scrub with a W7 flora, on damp to wet neutral soils

Hazel woodland (forms of W9 and W11)

Woodland with abundant Arrhenatherum elatius and/or Dactylis glomerata (related to W10)

Oak/birch woodland with Luzula sylvatica field layer (related to W10/11/16/17)

Oak-birch woodland with species-poor W11 field layer

Alder woodland with a W11-type ground layer (a canopy/ground flora ‘mismatch’)

Ash woodland with a W11 ground layer (another canopy/ground flora ‘mismatch’)

Western oak/birch woodland with Molinia-Vaccinium field layer (W4-17 NVC intermediate)

Aspen woodland in upland areas (forms of W11 and W17)

Pinus sylvestris-Molinia caerulea woodland (a form of W18d)

Pinus sylvestris-Cladonia woodland

Acidic Salix lapponum montane willow scrub (a form of W20)

Conifer plantation

Elder scrub (related to W21)

Broom scrub (a form of W23)

Ulex gallii scrub

Rhododendron ponticum in woodland and more open scrub

Buddleja davidii scrub

Knotweed scrub



DWARF SHRUB HEATHS – PAGE 6

Species-poor Calluna vulgaris heath intermediate between H9 & H12



Calluna vulgaris-Erica cinerea-Vaccinium myrtillus heath intermediate between H10 and H12 (H10-12)

Erica cinerea heath (a form of H10)

Calluna vulgaris-Vaccinium myrtillus heath with abundant Racomitrium lanuginosum (a form of H12)

Calluna vulgaris-Vaccinium myrtillus heath with abundant Carex bigelowii (a form of H12)

Species-poor prostrate/wind-clipped Calluna vulgaris heath (related to H13/14)

Short Calluna-Empetrum heath without Erica or Vaccinium

Calluna vulgaris heath with mesotrophic herbs

Western Calluna vulgaris-Arctostaphylos uva-ursi heath

Calcicolous Arctostaphylos uva-ursi heath

Damp, non-montane Vaccinium myrtillus heath (related to H18/H21)

Western heathy flush with Schoenus nigricans (a form of M15a)

Trichophorum germanicum-Narthecium ossifragum vegetation (closest to M15a)

Calluna vulgaris-Molinia caerulea wet heath (a form of M15b)

Racomitrium-Cladonia variation within M15c Trichophorum-Eriophorum bog, Cladonia sub-community

Short wet heath with abundant dwarf juniper (a form of M15c)

Montane Trichophorum-Empetrum-Racomitrium wet heath (a form of M15c)

Montane Trichophorum-Vaccinium-Empetrum wet heath (a form of M15d)

Wet heath with abundant Ulex gallii (related to M15)

Trichophorum germanicum-dominated wet heath (M15/M16)

BOGS – PAGE 12

M17-type bog with little or no S. papillosum

Bog with abundant Schoenus nigricans (a form of M17)

Racomitrium-Cladonia variation within M17b Trichophorum-Eriophorum bog, Cladonia sub-community

Eriophorum vaginatum bog (M20) – form with abundant Sphagnum fallax and/or Polytrichum commune

Eriophorum vaginatum bog (M20) – drier form with other graminoids

RUSH-DOMINATED VEGETATION – PAGE 13

Juncus effusus acid grassland community

Juncus acutiflorus acid grassland community

Juncus acutiflorus neutral grassland (related to MG10 & M23a)

Juncus articulatus neutral rush mire (closely related to M23a)

Juncus conglomeratus neutral grassland (closely related to MG10a)

Juncus conglomeratus neutral rush mire (closely related to M23b)

Species-poor Juncus squarrosus vegetation (a form of U6)



Juncus squarrosus vegetation with Carex bigelowii (a form of U6)

Juncus squarrosus-Calluna vulgaris heath

Herb-rich Juncus squarrosus flush


OTHER WETLANDS – PAGE 17

Neutral small sedge mire (related to M5/6/10/23)



Equisetum palustre neutral mire (related to M23)

Molinia caerulea-Schoenus nigricans flush (a form of M25c)

Molinia caerulea-Myrica gale mire (a form of M25a)

Potamogeton polygonifolius soakway (a form of M29)

Phragmites australis-Juncus-Filipendula ulmaria fen (a form of S25 without Eupatorium)

Carex lasiocarpa mire

Carex acuta swamp

Carex aquatilis swamp

Iris pseudacorus swamp

Ranunculus lingua swamp

Menyanthes trifoliata swamp

Menyanthes trifoliata bog pool

GRASSLANDS – PAGE 20

Montane Deschampsia flexuosa acid grassland



Festuca-Agrostis acid grassland + abundant Carex nigra (a form of U4a)

Northern forms of U4c acid-neutral grassland (without betony)



Festuca-Agrostis acid grassland with abundant Alchemilla alpina (a form of U4e)

Festuca-Agrostis acid-neutral grassland with damp-loving mesotrophic herbs (a flushed, enriched form of U4)

Nardus stricta-Calluna vulgaris-Racomitrium lanuginosum acid grassy heath (a form of U5e)

Nardus stricta acid grassland with abundant Alchemilla alpina (a form of U5e)

Nardus stricta-Trichophorum germanicum-Narthecium ossifragum vegetation (a form of U5e)

Liverwort-rich Nardus stricta snowbed grassland (a form of U7a)

Species-poor Molinia caerulea acid grassland (a form of M25)

Deschampsia cespitosa grassland including acidophilous species (related to MG9)

Holcus lanatus neutral grassland

Holcus lanatus/mollis neutral grassland

Holcus mollis neutral grassland

Holcus lanatus-Agrostis stolonifera-Ranunculus repens neutral grassland

Festuca rubra-Holcus lanatus neutral grassland

Elytrigia repens grassland

Poa annua neutral grassland

Helictotrichon pratense neutral-basic grassland

FERN-DOMINATED VEGETATION – PAGE 25

Bracken-dominated vegetation with herbs of damp mesotrophic soils

Bracken-Molinia vegetation (related to U20)

Dryopteris affinis vegetation

Dryopteris dilatata vegetation

Blechnum spicant vegetation

MONTANE SUMMITS & SNOWBEDS– PAGE 26

Fell-field

Lichen heath

Racomitrium ericoides moss-heath

Carex bigelowii swards

Pohlia ludwigii snowbed

Racomitrium heterostichum snowbed

Mixed snowbed



COASTAL VEGETATION – PAGE 28

Schoenus nigricans-Eupatorium cannabinum sea-cliff community

Catabrosa aquatica community

OTHER HABITATS – PAGE 29

Racomitrium lanuginosum rock/scree community

Racomitrium ericoides shingle vegetation

Pioneer bryophyte vegetation on disturbed upland acid soils



Polytrichum commune-dominated vegetation

Ivy-dominated vegetation on cliffs



Rubus idaeus underscrub

Cirsium arvense-dominated vegetation

Rumex obtusifolius vegetation

Petasites hybridus-Urtica dioica-Aegopodium podagraria vegetation

Impatiens glandulifera vegetation

REFERENCES – PAGE 32

APPENDIX – PAGE 33

WOODLAND AND SCRUB
Salix aurita scrub with a W4-type ground flora, on damp to wet acid soils

Salix aurita scrub with ground vegetation including good quantities of at least one of Molinia caerulea, Sphagnum spp. and Polytrichum commune. It has the wet, acidophilous ground layer characteristic of W4, and for this reason the vegetation appears better regarded as a scrub form of W4 than as a rather poor fit for W1 Salix cinerea-Galium palustre woodland, which differs in the canopy species as well as the ground flora. The S. aurita form of W4 is scattered widely on moist to wet ground in the Scottish Highlands, especially in lightly grazed western areas. It has been mapped using the code ‘W4Scr’ in some NVC surveys by Ben and Alison Averis.
Salix aurita scrub with a W7-type ground flora, on damp to wet neutral soils

Salix aurita scrub with ground vegetation including mesotrophic species such as Filipendula ulmaria, Geum rivale, Crepis paludosa, Galium palustre, Juncus effusus, J. acutiflorus, Lysimachia nemorum, Carex remota and the mosses Calliergonella cuspidata, Brachythecium rivulare, Kindbergia praelonga and Rhizomnium punctatum. This is the typical wet mesotrophic ground layer of W7, and for this reason the vegetation appears better regarded as a scrub form of W7 than as a rather poor fit for W1 Salix cinerea-Galium palustre woodland, which has a somewhat different ground flora and generally Salix cinerea rather than S. aurita in the canopy. The S. aurita form of W7 is scattered widely on moist to wet, level to sloping ground in the Scottish Highlands, especially in lightly grazed western areas. It has been mapped using the code ‘W7Scr’ in some NVC surveys by Ben and Alison Averis.
Salix cinerea scrub with a W7-type ground flora, on damp to wet neutral soils

Similar to the Salix aurita form of W7 described above but with a canopy of S. cinerea. There is an obvious similarity to W1 Salix cinerea-Galium palustre woodland but the ground vegetation is typically more species-rich and with more Lysimachia nemorum, and with a very clear similarity to that found in taller W7. Found widely on moist to wet level to sloping ground, especially in upland areas.


Hazel woodland (forms of W9 and W11)

This is woodland with a canopy of hazel – either pure hazel or with just the very occasional other tree, but always with hazel as the clear dominant. It is found on well-drained ground, mainly in the west Highlands but also in western Ireland and rarely in other western parts of the UK. This habitat has been the focus of considerable attention in recent years, mainly because of the rich lichen and bryophyte flora found on and beneath many hazels. While there is no hazel-dominated category in the NVC, these hazelwoods can generally be classed as hazel-dominated forms of either of two NVC communities: W9 where the ground vegetation includes mixtures of species including Mercurialis perennis, Brachypodium sylvaticum, Stachys sylvatica, Sanicula europaea, Geranium robertianum, Geum urbanum and Allium ursinum, and W11 where there is a more grassy ground flora including species such as Agrostis capillaris, Anthoxanthum odoratum, Holcus mollis, Potentilla erecta, Veronica chamaedrys, Primula vulgaris, Viola riviniana, Blechnum spicant and Pteridium aquilinum. W9 indicates rather basic soils and W11 neutral to slightly acid soils. Oxalis acetosella and Hyacinthoides non-scripta can occur in W9 and W11 hazelwoods.


Woodland with abundant Arrhenatherum elatius and/or Dactylis glomerata (related to W10)

This woodland can have a canopy of various broadleaved species but especially oak, sycamore and ash. The ground vegetation consists mainly of tall swards of the grasses Arrhenatherum elatius and Dactylis glomerata, commonly mixed with other species including Holcus lanatus, H. mollis and Poa trivialis. The ground vegetation is species-poor and very similar to MG1 Arrhenatherum elatius neutral grassland but with a tree canopy overhead. This vegetation is widespread on well-drained neutral soils in the lowlands: in small blocks of woodland among enclosed farmland (for example in shelterbelts), in the outer parts of some larger woods, or in young broadleaved plantation woodland planted on previously open neutral grassland. Floristically it does not fit well into any NVC community. It is nearest to W10 Quercus robur-Pteridium aquilinum-Rubus fruticosus woodland but the great abundance of A. elatius and/or D. glomerata is not typical of that community.


Oak/birch woodland with Luzula sylvatica field layer (related to W10/11/16/17)

This is broadleaved woodland, mostly of oak and/or birch, with ground vegetation consisting of continuous dense carpets of Luzula sylvatica. The woodrush can be abundant to dominant on the ground in the oak-birch woodland communities W10, W11, W16 and W17, but in this ‘non-NVC’ woodland type (coded as ‘WLZ’ in the Forestry Commission’s Native Woodland Survey of Scotland) it is so strongly dominant that there are almost no associated plants and the vegetation cannot be clearly assigned to any particular NVC community. Woodrush-dominated W10/11/16/17 and the WLZ woodland are collectively quite common on well-drained mildly to strongly acidic soils in upland and upland fringe areas.


Oak-birch woodland with species-poor W11 field layer (a form of W11)

This is woodland of oak, birch, rowan, hazel and goat willow, and rather species-poor swards of the grasses Agrostis capillaris, Anthoxanthum odoratum and Holcus mollis. Other species can include Oxalis acetosella, Potentilla erecta, Galium saxatile and mosses such as Rhytidiadelphus squarrosus, but the vegetation lacks species indicative of any of the four sub-communities. This kind of grassy, species-poor W11 is common on well-drained, lightly to moderately grazed ground in upland areas. It has been mapped using the code ‘W11SP’ or just ‘W11’ in NVC surveys by Ben and Alison Averis.


Alder woodland with a W11-type ground layer (a canopy/ground flora ‘mismatch’)

This is a confusing mixture: a canopy of Alnus glutinosa over a ground layer which is not the wet woodland type one would expect, but instead is a mixture of grasses such as Holcus mollis, Agrostis capillaris and Anthoxanthum odoratum, along with some other species such as Oxalis acetosella and Viola riviniana. The ground layer is of the W11 type, reflecting the ground conditions which are not noticeably wet. This odd mix of ‘wrong’ canopy and ground flora combination is uncommon but does occur on the banks of some rivers in the west Highlands, and is very locally a little more extensive in grazed valley floor woodland in the west Highlands. It could also occur in other parts of Britain and Ireland. It seems better to call it an alder-dominated form of W11 than a ‘dry’ form of W7.


Ash woodland with a W11 ground layer (another canopy/ground flora ‘mismatch’)

This is rather like the alder/W11 woodland just described, but with a canopy dominated by ash Fraxinus excelsior. Ash is more characteristic of W8/9 woodland on more basic soils, but occasionally (in grazed upland areas) one finds a group of ash trees forming a small patch of woodland where the ground vegetation has the W11-type mix of species such as Holcus mollis, Agrostis capillaris, Anthoxanthum odoratum, Oxalis acetosella, Viola riviniana and Potentilla erecta. It seems better to call it an ash-dominated form of W11 than a ‘more acidic’ form of W9.


Western oak/birch woodland with Molinia-Vaccinium field layer (W4-17 NVC intermediate)

This is western woodland, mostly of oak but also with some birch and rowan, and with ground vegetation including an abundance of Molinia caerulea and Vaccinium myrtillus accompanied by other species such as Potentilla erecta and the mosses Hylocomium splendens, Pleurozium schreberi, Hypnum jutlandicum and Rhytidiadelphus loreus. The abundance of M. caerulea suggests W4 while that of V. myrtillus suggests W17. The canopy (mostly oak) and the habitat (mostly on slopes) are generally closer to those of W17 than those of W4. This kind of woodland can be classed as intermediate between W4 and W17 (i.e. W4-17) but is mentioned here because it is locally common in the southern half of the west Highlands; in some places it makes up a high proportion of the total woodland extent. It might also occur in other western upland areas.


Aspen woodland in upland areas (forms of W11 and W17)

Stands of aspen can be very distinctive visually as well as having their own particular ecological interest. As with hazel there has been a recent surge of interest in this species. Although there is no aspen-dominated community in the NVC, these upland aspen woods can generally be classed as aspen-dominated forms of W11 where there is a grass/herb ground flora including species such as Agrostis capillaris, Anthoxanthum odoratum, Holcus mollis, Potentilla erecta, Veronica chamaedrys, Primula vulgaris, Viola riviniana, Anemone nemorosa, Blechnum spicant and Pteridium aquilinum, or W17 where the ground vegetation is more heathy, including Calluna vulgaris, Vaccinium myrtillus or Deschampsia flexuosa together with an abundance of mosses. These aspen stands are uncommon nationally but are a special feature of some east Highland areas such as Speyside.


Pinus sylvestris-Molinia caerulea woodland (a form of W18d)

This is native Pinus sylvestris woodland with a field layer of Molinia caerulea. There is generally at least a sparse scatter of Calluna vulgaris, Erica tetralix and mosses such as Sphagnum capillifolium, Hypnum jutlandicum and Hylocomium splendens. This kind of woodland is uncommon in the Highlands – mainly in the west. It can be accommodated within the sub-community W18d (Sphagnum capillifolium/quinquefarium sub-community), but the abundance of Molinia makes it very different in appearance to ‘mainstream’ W18d which is very heathy with dwarf shrubs (especially Calluna) abundant or dominant in the field layer. It can therefore be worth separating the examples with abundant Molinia, for example by using a provisional code such as W18dM.


Pinus sylvestris-Cladonia woodland

This kind of Pinus sylvestris woodland, with a striking ground layer of large, branched, whitish-coloured lichens of the genus Cladonia, was first described from Britain by Watson & Birse (1990). The ground vegetation can include some dwarf shrubs such as Calluna vulgaris and Vaccinium myrtillus, and grasses such as Deschampsia flexuosa, but is less mossy than most W18 Pinus sylvestris-Hylocomium splendens woodland. This Pinus-Cladonia woodland (coded as ‘WP’ in the Forestry Commission’s Native Woodland Survey of Scotland) occurs sparingly on level to gently sloping well-drained ground with acid soils in north-eastern Scotland, especially at low altitudes in the Moray Firth area. It shows floristic affinities to lichen-rich pine woodland in Scandinavia.


Acidic Salix lapponum montane willow scrub (a form of W20)
The archetypal montane willow scrub is a community of base-rich soils, where species such as Salix lapponum, S. myrsinites, S. arbuscula and more rarely S. lanata grow in a lush understory of tall mesotrophic herbs and small calcicolous species. However S. lapponum, the least base-demanding of these species, also grows in more acid places where the accompanying vegetation is made up of species such as Erica tetralix, Calluna vulgaris, Vaccinium spp., Potentilla erecta, Trichophorum germanicum and the mosses Racomitrium lanuginosum and Sphagnum denticulatum. Small patches of this type of scrub are scattered widely on mountains in the Highlands, with outliers in the southern uplands.
Conifer plantation

Dense plantations of pines, spruces, firs, larches and western hemlock typically have a species-poor ground flora limited by the shade cast by the conifers, and by the extensive carpets of fallen conifer needles. This ground vegetation tends to be mossy, including shade-tolerant species such as Hypnum jutlandicum, Plagiothecium undulatum and Mnium hornum. It can show affinities with W4 (acidic and damp to wet), W10, W11, W16, W17 and W18 (all mildly to strongly acidic) but this type of conifer plantation vegetation is not covered in the present NVC. These plantations are widespread and very common on acid soils and are especially extensive in many upland areas.


Elder scrub (related to W21)

Elder scrub can be accommodated within W21 Crataegus monogyna-Hedera helix scrub but is sufficiently distinct from hawthorn-dominated W21 that it seems worthy of a separate category. It occurs patchily on well-drained ground, evidently with neutral soils, and in many places with some eutrophication, in the lowlands. Meanwhile, where it occurs in mosaics with hawthorn scrub a suffix can be added to the W21 label to indicate elder dominance (e.g. W21Eld).


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