An Ancient Woodland Indicator (AWI) species list

Early purple orchids, bluebells and ramsons, are all strong indicator species of ancient woodland.

There has been a long history of botanists surveying the British Isles and compiling lists of the flora found. When those plant lists are cross referenced against the historical evidence for woodland, then it becomes apparent that there are plant species intimately associated with woods that have a long history.  Historical woodland ecologists have demonstrated from plant surveys that medieval secondary woodland detached from primary woodland is still deficient in many woodland plants and even medieval secondary woodland adjacent to primary woodland can be poorer in the numbers of woodland specialists, which implies ancient woodland is an irreplaceable habitat.

Yellow archangel, dog's mercury, herb paris, ramsons, hart's-tongue ferns, bluebells and a derelict wych elm coppice stool with suckers.

The Woodland Trust commissioned Sheffield Hallam University to research and survey the coverage, use and application of Ancient Woodland Indicator Lists in the UK and in the report appendix is a table of 37 regional and county AWI species lists, including one from central/northern Europe. Yew (Taxus battaca) featured on just 7 lists which I found odd as a Yew authority Toby Hindson wrote about the ages of woodland Yews at Alice Holt Inclosure in Hampshire.

The categorisation of yews by age or size is a thorny issue, I use 5 meters or 16.7 feet in churchyards as the watershed for “ancient”. Experience has led me to regard any wild yew over 12 feet in girth as unusually large and important, a wild specimen over 14 feet in girth I have found to be very rare.

A woodland Yew with a girth of 3m is over 400 years old and that age precedes the AD1600 cut off point for planted woodland. As far as I know there have been no record of notable yews in secondary woodland. Yews over 3m girth are not uncommon in the ancient woods of West Gloucestershire, Herefordshire, Monmouthshire and Powys, even in those woods overlying acidic sandstones.

Two yews well over 400 years in age in a beech plantation. Elsewhere in the wood are out size small leaved lime coppice and veteran pollarded beech. The ground flora consists of wood anemones, bluebells, dog's mercury and ramsons. 

In lieu of an AWI species list for Herefordshire/ West Gloucestershire that covers the Forets of Dean/Lower Wye Valley  I compiled a proxy list* from the species lists for East Wales (81 species), South Wales (103 species), South East Wales (87 species), South West (110 species), Shropshire (90 species) and Worcestershire (109 species). The rationale being the bedrock geology, topography, proximity, climate and the mixed broadleaved woods of the Welsh borderlands. Although I'm clueless on being able to name many of the grasses, sedges, rushes and wild flowers in the field, there does seem to be a fair correlation between the ones I am aware of when in leaf or flower and ancient woodland. Links to the scientific name go to the plant species page at the Online Atlas of the British and Irish flora and distribution maps. (SWE) South West England, (SW) South Wales, (EW) East Wales, (SEW) South East Wales, (Sh) Shropshire, (Wo) Worcestershire.

Trees and shrubs

Number of         Scientific name                         Common name
Lists (Max 6)

          6                Acer campestre                          Field maple
          6                Euonymus europaeus                 Spindle
          6                Quercus petraea                         Sessile oak
          6                Sorbus torminalis                       Wild service tree
          6                Tilia cordata                               Small leaved lime
          6                Ulmus glabra                             Wych elm
          5                Daphne laureola                        Spurge-laurel (SWE,Sh,Wo,SW,SEW)
          5                Frangula alnus                           Alder buckthorn (Wo, SWE, SW, EW, SEW)
          5                Populus tremula                         Aspen (SWE,So,SW,EW.SEW)
          5                Viburnum opulus                       Guelder rose(Sh, SWE, SW, EW, SEW)
          4                Ilex aquifolium                          Holly (SWE,So,SW,EW)
          4                Prunus avium                             Wild cherry (SWE,Wo,SW,EW)
          4                Taxus baccata                             Yew (Sh, SEW, SW, EW)
          4                Ribes rubrum                             Redcurrant (SEW,SW,EW,SEW)
          3                Prunus padus                              Bird cherry (SW, EW, SEW)
          2                Daphne mezereum                     Mezereon (SW,SEW)
          2                Rhamnus cathartica                    Purging buckthorn (SW,SEW)
          2                Tilia platyphyllos                       Large leaved lime (Sh,Wo)
          2                Cornus sanguinea                       Dogwood (Sh,Wo)

          1                Crataegus laevigata                    Woodland hawthorn (Wo)
          1                Ribes nigrum                              Black current (SW) 
          1                Salix caprea                                Goat willow (SW)
          1                Sorbus (microspecies)                Whitebeam  (SWE)

Ferns 

Number of         Scientific name                         Common name
Lists (Max 6)

        6              Polystichum aculeatum              Hard shield-fern
        6              Equisetum sylvaticum               Wood horsetail
        6              Dryopteris affinis                       Scaly male fern 

        5              Blechnum spicant                      Hard fern (SWE,Sh,Wo,SW,SEW)
        5              Polystichum setiferum               Soft shield-fern (SWE, Sh,Wo,EW, SEW)

        4              Dryopteris carthusiana              Narrow buckler-fern (SWE,Sh,Wo,SW)

        4              Dryopteris aemula                     Hay-scented buckler-fern (SWE,SW,EW,SEW)
        4              Oreopteris limbosperma             Lemon-scented fern (SWE,Sh,Wo,SW)
        4               Polypodium vulgare                 Common polypody fern (SWE,Wo,SW,EW)
        3              Gymnocarpium dryopteris        Oak fern (Wo, SW,SEW)
        3              Phyllitis scolopendrium             Hart's-tongue fern (SW,Wo, EW)
        2              Hymenophyllum tunbrigense    Tumbridge filmy film (SWE, SW)
        2              Phegopteris connectilis              Beech fern (SWE,SW)
        1              Athyrium filix-femina                Lady fern (Wo)
        1              Hymenophyllum wilsonii          Wilson's filmy fern (SW)

Thelypteris phegopteris 

Grasses, rushes and sedges 

Number of         Scientific name                         Common name
Lists (Max 6)

         6              Bromopsis ramosa                   Hairy brome 

         6              Carex laevigata                        Smooth-stalked sedge 

         6              Carex pendula                          Weeping sedge
         6              Carex remota                            Remote sedge
         6              Carex sylvatica                        Wood-sedge

         6              Carex strigosa                          Thin-spiked Wood-sedge
         6              Elymus caninus                        Bearded couch

         6              Luzula pilosa                            Hairy wood-rush
         6              Luzula sylvatica                       Great wood-rush 

         6              Melica uniflora                         Wood melick 

         6              Milium effusum                       Wood millet 

         6              Poa nemoralis                          Wood bluegrass 
         6              Scirpus sylvaticus                    Wood club-rush

         5              Carex pallescens                      Pale sedge (SWE,Sh,Wo,SW,SEW)

         5              Festuca gigantea                       Giant fescue (SWE,Sh,SW,EW,SEW)

         5              Luzula forsteri                         Southern wood-rush (SWE, Wo, SW, EW, SE)

         3              Festuca altissima                      Wood fescue (Sh,Wo,SW)
         3              Holcus mollis                           Creeping soft-grass (SWE,SW,EW)

         2              Hordelymus europaeus            Wood-barley (Sh,Wo)

         3              Melica nutans                           Mountain melick (Sh,Wo,EW)

         2              Calamagrostis epigejos            Wood small-reed (SWE,Wo)
         2              Carex montana                         Soft-leaved sedge (SWE,Wo)
         2              Carex paniculata                       Greater tussock-sedge (SWE,Wo)

         1              Bromopsis benekenii                Lesser hairy-brome (Sh)
         1              Carex elongata                          Elongated sedge (Wo)
  

Flowering plants

Number of         Scientific name                         Common name
Lists (Max 6)

         6              Adoxa moschatellina                Moschatel
         6              Allium ursinum                        Ramsons
         6              Galium odoratum                     Woodruff                
         6             Anemone nemorosa                  Wood anemone  
         6             Campanula trachelium              Nettle-leaved bellflower
         6             Chrysosplenium oppositifolium  Opposite-leaved golden-saxifrage              
         6              Epipactis helleborine                Broad-leaved helleborine 
         6              Euphorbia amygdaloides          Wood spurge
         6              Hypericum androsaemum        Tutsan  
         6              Lamiastrum galeobdolon         Yellow archangel 
         6              Lathraea squamaria                  Toothwort 
         6              Lysimachia nemorum               Yellow pimpernel
         6              Geum rivale                              Water avens 
         6              Hyacinthoides non -scripta      Bluebell
         6               Neottia nidus-avis                     Bird's-nest orchid 
         6               Orchis mascula                         Early-purple orchid
         6              Oxalis acetosella                       Wood sorrell   
         6              Paris quadrifolia                       Herb paris 
         6              Primula vulgaris                       Primrose
         6              Ranunculus auricomus             Goldilocks buttercup 
         6              Sanicula europaea                    Wood sanicle
         6               Veronica montana                    Wood speedwell 
         6              Vicia sylvatica                          Wood vetch
         6              Viola reichenbachiana              Early dog-violet 
         5         Chrysosplenium alternifolium   Alternate-leaved golden-saxifrage (Sh,Wo,SW,EW,SEW)
         5              Conopodium majus                  Pignut (SWE,Wo,SW,EW,SEW)
         5              Convallaria majalis                  Lilly of the valley (SWE,Sh,SW,EW,SEW)
         5              Iris foetidissima                        Stinking iris (SWE,Sh,Wo,SW,SEW)
         5              Melampyrum pratense              Common cow-wheat (SWE,Wo,SW,EW,SEW)
         5              Mercurialis perennis                Dog's mercury (Sh,Wo,SW,EW,SEW)
         5              Moehringia trinervia                Three-nerved sandwort (SWE,Sh,SW,EW,SEW)
         5              Platanthera chlorantha              Greater butterfly-orchid (SWE,Sh,Wo,SW,SEW)
         5              Polygonatum multiflorum         Solomon's seal (SWE,Sh,SW,EW,SEW)
         5              Solidago virgaurea                    European goldenrod (SWE,Sh,Wo.SW,EW)
         4              Aquilegia vulgaris                    Columbine (SWE,Wo,SW,EW)
         4              Helleborus viridis                     Green hellebore (SW,So,Wo,EW)
         4              Lathyrus linifolius                    Bitter vetch (SWE,Wo,SW,EW)
         4              Lathyrus sylvestris                   Narrow-leaved everlasting-pea (SWE,Sh,Wo,EW) 
         4              Myosotis sylvatica                   Wood forget-me-not (Sh,Wo,SW.EW)
         4              Potentilla sterilis                       Barren strawberry (SWE,Sh,SW,SEW)
         4              Narcissus pseudonarcissus        Wild daffodil (SEW,Sh,Wo,EW)
         3              Campanula latifolia                  Giant bellflower (Sh,Wo,EW)
         3               Dipsacus pilosus                       Small teasel (SWE,Sh,Wo)
         3              Hypericum pulchrum                Slender St John's-wort (SWE,Wo,SW)
         3              Melittis melissophyllum           Bastard balm (SWE,SW,SEW)
         3              Scrophularia nodosa                 Figwort (SW,EW,SEW
         3               Stachys officinalis                    Betony (SWE,Sh,Wo)
         3              Stellaria nemorum                    Wood Stitchwort (SEW, SW, EW)
         3               Tamus communis                     Black byrony (SWE,SW,EW)
         3              Vaccinium myrtillus                  Bilberry (SWE,Wo,SW)
         3              Vicia sepium                             Bush vetch (SWE, SW, EW)
         2              Aconitum napellus                    Monk's hood (SEW,Wo) 
         2              Calluna vulgaris                        Heather (SW,SEW)
         2              Ceratocapnos claviculata          Climbing corydalis (SWE,SW)
         2              Colchicum autumnale               Autumn crocus (SWE,Wo)
         2              Corydalis claviculata                 Climbing corydalis (SWE,SEW)

         2              Epipactis purpurata                    Violet Helleborine (Sh,Wo)

         2              Gagea lutea                               Yellow Star-of-Bethlehem (Sh,Wo)

         2              Geranium sylvaticum                Wood cranesbill (Sh,Wo)

         2              Gnaphalium sylvaticum             Wood cudweed (Sh,Wo)

         2              Listera ovata                              Common twyblade (Sh,Wo)

         2              Sedum telephium                       Orpine (SWE,Wo)

         2              Stellaria holostea                       Greater stitchwort (Wo,EW)   

         2              Stellaria neglecta                        Greater chickweed (SW,SEW)

         1              Arum maculatum                       Lord and Ladies (Sh)

         1              Campanula patula                      Spreading bell flower (Wo)   

         1              Cephalanthera damasonium      White helleborine (Wo)
         1              Cephalanthera longifolia           Narroe leaved helleborine (Wo)
         1              Circaea lutetiana                         Enchanter's nightshade (EW) 
         1              Fragaria vesca                            Wild strawberry (Sh)
         1              Geranium sanguineum               Bloodt Cranesbill (Wo)
         1              Geum urbanum                          Wood avens (SW)

         1              Helleborus foetidus                    Stinking hellebore (Sh,Wo)

         1              Hypericum hirsutum                  Hairy St John's-wort (EW)  

         1              Lonicera periclymenum             Honeysuckle (SW)
         1              Pimpinella major                       Greater burnet-saxifrage (Wo) 
         1              Polygonatum odoratum             Angular Solomon's-Seal (EW)
         1              Ruscus aculeatus                       Butcher's-broom  (SWE)  
        

There are caveats with AWI species lists: soil pH, hydrology, site topography and historic woodland management will influence the species present. 

* For reference Oliver Rackhams 2006 AWI species list for England and Wales. Numbers in parentheses indicate the number of lists the species appeared on with a theoretical maximum of max number of 18.

Adoxa moschatellina              Moschatel (12)
Agropyron (Elymus) canium  Bearded couch (8)
Allium ursinum                       Ramsons (9)
Anemone nemorosa                Wood anemone (15)
Aquilegia vulgaris                   Columbine  (4)
Bromus ramosus                     Hairy brome (5)
Calamagrostis canescens        Purple small-reed (2)
Calamagrostis epigejos           Wood small-reed (5)
Campanula trachelium            Nettle-leaved bellflower (6)
Carex laevigata                       Smooth-stalked sedge (8)
Carex pallescens                     Pale sedge (10)
Carex pendula                        Weeping sedge (10)
Carex remota                          Remote sedge (10)
Carex strigosa                        Thin-spiked Wood-sedge (11)
Carex sylvatica                      Wood-sedge (7)
Ceratocapnos claviculata       Climbing corydalis (8)
Chrysosplenium oppositifolium Opposite-leaved golden-saxifrage (3)
Colchicum autumnale            Autumn crocus (4)
Conopodium majus                Pignut (7)
Convallaria majalis                Lilly of the valley (9)
Crataegus laevigata                Woodland hawthorn (4)
Dipsacus pilosus                    Small teasel (2)
Dryopteris affinis                   Scaly male fern (6)
Dryopteris aemula                 Hay-scented buckler-fern (4)
Epipactis helleborine             Broad-leaved helleborine (6)
Epipactis leptochila               Narrow-lipped helleborine (3)
Epipactis purpurata                Violet Helleborine (5)
Euphorbia amygdaloides       Wood spurge (12)
Festuca gigantea                     Giant fescu (7)
Galium odoratum                   Woodruff (17)
Geum rivale                           Water avens (5)
Helleborus viridis                  Green hellebore (5)
Hordelymus europaeus          Wood-barley (5)
Hyacinthoides non-scripta Bluebell (3)
Hymenophyllum tunbrigense Tunbridge filmy fern (2)
Hymenophyllum wilsonii      Wilson's filmy-fern (3)
Hypericum androsaemum     Tutsan  (5)
Hypericum hirsutum              Hairy St John's-wort
Lamium galeobdolon            Yellow archangel (9)
Lathraea squamaria               Toothwort (7)
Lathyrus linifolius                 Bitter vetch (6)
Luzula pilosa                         Hairy wood-rush (15)
Luzula sylvatica                    Greater wood-rush (6)
Lysimachia nemorum            Yellow pimpernel  (6)
Maianthemum bifolium        May lily (1)
Melampyrum cristatum        Crested cow wheat (1)
Malus sylvestris                    Crab apple (8)
Melica unifloa                       Wood mellick (18)
Melittis melissophyllum       Bastard balm (3)
Mercurialis perennis             Dog's mercury (3)
Milium effusum                    Wood millet (14)
Moehringia trinervia             Three-nerved sandwort (4)
Myosotis sylvatica                Wood forget-me-not (4)
Narcissus pseudonarcissus    Wild daffodil (4)
Neottia nidus-avis                 Bird's-nest orchid (10)
Orchis mascula                     Early purple orchid (8)
Oxalis acetosella                  Wood sorrell (10)
Paris quadrifolia                   Herb paris (12)
Platanthera chlorantha          Greater butterfly-orchid (6)
Poa nemoralis                      Wood bluegrass (5)
Polygonatum multiflorum    Solomon's seal (4)
Populus tremula                   Aspen (4)
Potentilla sterilis                  Barren strawberry (2)
Primula elatior                     Oxlip (2)
Primula vulgaris                   Primrose (3)
Quercus petraea                    Sessile oak (2)
Ranunculus auricomus         Goldilocks buttercup (4)
Ruscus aculeatus                  Butcher's-broom (2)
Salix caprea                         Goat willow (2)
Sanicula europaea                Wood sanicle (5)
Scirpus sylvaticus                Wood club-rush (5)
Scrophularia nodosa             Figwort (4)
Sedum telephium                 Orpine (3)
Sorbus Torminalis               Wild service tree (15)
Tilia cordata                         Small leaved lime (14)
Tilia platyphyllos                 Large leaved lime (2)
Veronica montana                Wood speedwell (10)
Vicia sylvatica                      Wood vetch (5)
Viola reichenbachiana          Early dog-violet (6)

Ramsons carpets

Two recent woodland trips provided the inspiration for this post on ramsons (Alium ursinum). The first trip was an afternoon recce for some uncommon woodland flora when a visually compelling ramsons carpet was chanced upon in less than ideal lighting. Another location identified and added to the seemingly ever lengthening 'to visit under more idealised lighting' list.

To increase the chances of finding ramsons carpets an appreciation of their ecology is useful and a Hungarian research paper provides some useful insight into the habitat requirements amongst other things:

"In spite of its broad distribution across continents, and its occurrence as a weed, the species cannot be considered as a generalist. Several authors have classified it as a habitat specialist, having a rather narrow range of ecological tolerance (Grime et al. 1988, Kevey 1977, Rychnovská and Bednář 1998). A. ursinum is particularly sensitive to the availability of water. It requires a mesic soil, which is well-drained. Both drought and waterlogging are unfavourable (Csiky et al. 1999, Grime et al. 1988, Kevey 1977, Rychnovská and Bednář 1998, Trémolières et al. 2009, Tutin 1957). Sufficient humidity in the air is also crucial for survival (Kevey 1977, Kovács 2007)."

"The species strongly prefers the forest floor; it can rarely be found outside of a forest (Grime et al. 1988), only in some places with high, evenly distributed precipitation (Tutin 1957) or along rivers or streams (Kevey 1977)." 

"The plant requires a nutrient-rich soil (Tutin 1957)"

"A. ursinum is sensitive to the pH, missing from base-poor sands and mor soils (Tutin 1957). Falkengren-Grerup and Tyler (1993) demonstrated experimentally that mor (pH 3.6) inhibited the production of new roots. Tutin (1957) estimated the tolerated pH range from 5.5 to 7.9; Grime et al. (1988) narrowed it to 6–7.5" 

Extracts taken from Oborny, B., Botta-Dukat, Z., Rudolf, K. and Morschhauser, T., 2011. Population ecology of Allium ursinum, a space-monopolizing clonal plant. Acta Botanica Hungarica, 53(3-4), pp.371-388.

Ransoms are an indicator species of ancient woodland and some online detective work cross referencing national ancient woodland inventories e.g. Wales and England, against a relevant geology map will identify candidate sites of ancient woodland overlying calcareous bedrock. It is then a case of recceing the candidate woods.

The second trip was one made specifically to photograph a riparian carpet of ramsons within the Lower Wye Valley AONB on a rare day with overcast skies, the weather in May, thus far, has been mostly clear blue skies and sunshine. The woodland is designated as ancient semi natural and has outsize coppice stools of alder, ash, wych elm and hazel with a ground flora community of ancient woodland indicator species.