TRANSACTIONS SOME OBSERVATIONS O N THE FLORA OF THE MARGINS OF THE A12 W . J . PLUMB
Introduction DR. Way (1970) has suggested that the verges of motorways can act as important reservoirs of wildlife. H e points out that one mile of motorway absorbs twenty acres of land, 40% of which is verge or bank, and is sown with a basic seed mixture and provides a linear habitat of considerable ecological value because it transects many habitats. It is protected by virtue of its nature and constancy of management could easily be arranged. Dr. Way argues that no other function has been proposed for the motorway verges but also that people cannot inspect and enjoy wildlife on a motorway and the verges are too new quickly to become areas of outstanding biological interest. Since older verges have had a fairly constant degree of management over a longer period of time it would be reasonable to expect them to support a richer and more stable flora than the relatively new verges of the motorways. T h e principle aims of the present study were to investigate the effectiveness of the verges of the A I 2 as reserves for wild plants and to examine the factors which may determine the distribution of the flora on the verges. T h e account may also act as a starting point for the fuller documentation of the flora of Suffolk's roadside verges. There appears to be very little recorded information on this important habitat although Pierce and Ranson (1971) gave a good general account and included a list of those Suffolk verges meriting specific conservation measures. Methods An approximately seven mile Stretch of the A I 2 south-west of Ipswich was chosen as the area for study. A survey was made of the Vegetation at five sites each chosen as having different characteristics to give a representative cross-section of the habitats transected by the carriageway. Each site consisted of an approximately fifty yard Stretch of the carriageway, the total area of road margin examined amounting to little more than one acre. T h e distribution and abundance of each species was recorded and an attempt was made to relate these observations to the following features: (a) management, (b) adjoining land use, (c) width and slope of verge, (d) encroachment of scrub, (e) effect of salt and lead residues and m u d spray on the Vegetation at the edge of the verge, (/) soil types, (g) age of verge.
FLORA OF THE MARGINS
Description of sites Each site is described separately giving its location and the main habitats present. The most important elements in the flora are described and the various habitats compared. The letters in brackets following the names of plants in this section gives an indication of the relative abundance of the species at that site based on the following scale: A=abundant—covering large areas of verge; C=common—widespread on the verge and may be dominant locally; F=frequent—fairly generally distributed over the whole area or is found in a few large clumps; 0=occasional— scattered, up to fifteen specimens in the area covered; R=rare— less than five individuals in the area studied or restricted to a few small clumps. More precise quantitative assessments were not made except for some tree species. Site 1 TM 124425 At this site the land use on both sides of the carriageway is pasture. Four habitats can be defined: A : a bank about twelve feet high and rising quite steeply and facing north-west. In two places the bank is invaded by oak-hawthorn scrub but most of the bank is still open grassland and appears to be untouched except for the lower two feet which is cut at the same time as the verge. B: a verge about twelve feet wide. C: the central reservation which differs little in character from the verge. D: a bank dropping about four feet to a damp ditch, facing north-west and uncut. T A B L E 1 compares the dominant species in the four habitats. Sixty-four species were recorded at this site. Site 2 TM 105393 The road is bordered by Bentley Long Wood on the west and by arable on the east side. The wood provides dense shade over the west verge which is disturbed to some extent by lorries running over it. The soil on this verge tends to hold water. Three vegetational zones are distinguishable: A: the wood edge, B: the west verge shaded by the wood, C: the east verge and low dry bank facing west. The wood edge consists of Ulmus procera, Quercus robur, Fraxinus excelsior, Acer campestre with Rubus fructicosus and Hedera helix as undershrubs. Glechoma liederacea is prominent as a wide band from the wood edge, in places almost reaching the road. Other common species are Anthriscus sylvestris, especially at the wood edge, and Stellaria media with Polygonum aviculare near the roadside. This was the only site for Myosotis arvensis (R) and Anagallis arvensis (R). The most abündant grass appears to be Lolium perenne (A). Achillea millefolium (R) is noticeably scarce at this site whilst Plantago major is only common on bare areas near the roadside.
Suffolk Natural History, Vol. 16, Part 3
The more open, dry sunny Situation of the east verge supports a noticeably different flora. Arrhenatherum elatius (A) is the dominant grass with Dactylis glomerata common in the dry ditch. Piants unique to this site include Reseda luteola (R), Agrimonia eupatoria (R), and Euphorbia peplus (R). The most typical piants of the site are Galium aparine (O-F), Stellaria media (F-C), Heracleum sphondylium (O), Senecio vulgaris (F), and Urtica dioica (F). Site 3 TM 083372 A hedge of Crataegus monogyna and Sambucus nigra with Rubus fructicosus demarcates the western boundary of the carriageway. Three main habitats can be distinguished: A: an uncut hedge bottom with flora quite distinct from that of the verge, B : the verge which is adjacent to a layby and receives a great deal of trampling, especially around the litter basket, C: the east verge which merges into a bank rising about twelve feet and uncut except for the very bottom. The land use on both sides of the carriageway is orchards. T A B L E 2 shows the composition of the dominant species at site 3. TABLE 1
A comparison of the dominant species in the different habitats at site 1. iA uncut iB iC iD scrub bank verge reservation damp bank C C Glechoma hederacea Ground ivy C Anthriscus sylvestris Cow parsley C Dactylis glomerata Cocksfoot C Urtica dioica Stinging nettle C Centaurea nigra Hardhead A Deschampsia flexuosa Wavy hair-grass Stellaria graminea Lesser stitchwort Lotus corniculatus Corn birdsfoot trefoil Arrenatherum elatius False oat Heracleum sphondylium Hogweed Cirsium arvense Creeping thistle A Equisetum arvense Common horsetail Vicia hirsuta Hairy tare Vicia sativa Common vetch
c c c c c
FLORA OF THE MARGINS
Plantago lanceolata Ribwort plantain Achillea millefolium Yarrow Potentilla reptans Creeping cinquefoil Poa pratensis S m o o t h meadow-grass Convolvulus arvense Field bindweed Hordeum murinum Wall barley Stellaria media C o m m o n chickweed Polygonum aviculare Knotgrass Trifolium campestre H o p trefoil Trifolium pratense Red clover
iB iC verge reservation C C C C
iD damp bank
C C Q
Q (j C
T h e dominant species at site 3. Hedge West verge East verge and bank C
Urtica dioica Stinging nettle Lamium album White deadnettle Galium aparine Goosegrass Plantago lanceolata Ribwort plantain Potentilla reptans Creeping cinquefoil Arrhenatherum elatius False oat Dactylis glomerata Cocksfoot Trifolium campestre H o p trefoil Achillea millefolium Yarrow Rumex acetosella Sheep's sorrel Senecio jacobaea Ragwort Senecio vulgaris Groundsel Leontodon autumnalis A u t u m n hawkbit Equisetum arvense C o m m o n horsetail
C A C C A
C C C C C C C C
T h e east verge supports some species which were rarely recorded at other sites. These include Lathyrus pratensis (F), Chelidonium majus (R), Vicia sepium (R), Foeniculum vulgare (R), and Plantago
Suffolk Natural History, Vol. 16, Part 3
coronopus (O). On a narrow strip of verge bordering the layby three species are more prominent: Achillea millefolium (C), Senecio vulgaris (C), and Tripleurospermum maritimum (F). Among the less frequently found plants at site 3 were Tragopogon pratense (O), Geranium dissectum (F), Linaria vulgaris (O), and Pteridium vulgaris (O). The bank has some Ulex scrub in one place and some Crataegus monogyna scrub in another. Site 4 TM 077367 Only the east side of the carriageway was examined at this site. This consists of a sandy west-facing verge and bank rising about fifteen feet and adjoining an orchard. At least fifty-eight species occur at this site. Of these thirteen are common: Poa pratensis, Arrhenatherum elatius, Lolium perenne, Deschampsia flexuosa, Ranunculus bulbosa, Stellaria media, Vicia hirsuta, Leontodon autumnalis, Hypochaeris radicata, Centaurea nigra, Achillea millefolium, Plantago major, and Plantago lanceolata. A number of species found at this site were not recorded elsewhere: Filago germanica (R), Erigeron acer (R), Conyza canadensis (O), Centaurea scabiosa (R), Medicago sativa (R), Melilotus alba (R), Oenothera erythrosepala (O), and Calamintha nepeta (O). This bank has been planted with Pinus sylvestris and Acer pseudoplanatus. Both are at present very small and hidden in the grass but in time will presumably play an important part in determining the composition of the Vegetation on the bank. In addition to the plants this site supports a small colony of the Common Blue Butterfly Polyommatus icarus. Both of the principle food plants of this butterfly, Ononis repens (O) and Lotus corniculatus (O), occur at this site. Site 5 TM 071361 Land use on both sides of the carriageway is arable. The west side (5A) is bordered by a fence preventing the cutting of the Vegetation near it which therefore tends to be tall and coarse. This verge is dominated by Agropyron repens and few other plants were evident after the verge had been cut in July, 1971. Three species were common: Trifolium repens, Senecio vulgaris, and Ranuncuus bulbosus. The latter was more frequent here than at any other site. Capsella bursa-pastoris (F) and Artemisia vulgaris (F) were also commoner here than elsewhere. On the central reservation (5B) the only specimen of Euphorbia helioscopia was found. Ranunculus bulbosus (C), Plantago lanceolata (F), Taraxacum officinale (F), Rumex crispus (F), and Chrysanthemum vulgare (F) were the most characteristic species. Geranium dissectum (F) was only found here and at 2B. The east verge and bank (5C) support a different rĂ¤nge of species to the central reservation. The most characteristic species are Centaurea nigra (F), Chrysanthemum vulgare (F), Vicia sp. (F),
FLORA OF THE MARGINS
Galium aparine ( F ) , Anthriscus sylvestris ( C ) , Plantago lanceolata ( F ) , a n d Plantago major ( F ) . Lonicera periclymenum f o r m s a large c l u m p straggling over t h e verge a m o n g s t t h e grass. Galium mollugo ( R ) w a s f o u n d o n l y at t h i s site. T w o s p e c i m e n s of Tilia europaea a n d o n e of Betula verrucosa o c c u r at t h e e d g e of t h e field. S i t e 5 h a d o n l y t h i r t y - s e v e n s p e c i e s , t h e s m a l l e s t n u m b e r of all t h e sites. TABLE 3
A comparison of the n u m b e r of species recorded at each site. Site iA iB iC 2Ă„ 2Ă&#x; 3A 3B 4 5A 5B Number of Species 64 17 36 46 42 31 34 58 24 13
C o m p l e t e floral list All t h e s p e c i e s f o u n d a r e l i s t e d b e l o w . T h e n u m b e r of sites a t w h i c h e a c h s p e c i e s w a s f o u n d is g i v e n in b r a c k e t s a f t e r t h e s p e c i e s name. T h i s n u m b e r is o u t of e l e v e n as m o s t sites w e r e s u b d i v i d e d as i n d i c a t e d in t h e site d e s c r i p t i o n s . S e e also T A B L E 3. A m o r e d e t a i l e d i n v e s t i g a t i o n m a y s h o w t h e d i s t r i b u t i o n of s o m e s p e c i e s , e s p e c i a l l y t h e g r a s s e s , t o b e at v a r i a n c e w i t h t h a t g i v e n i n t h e list. A l s o it is q u i t e likely t h a t e x t r a s p e c i e s w o u l d b e a d d e d t o t h e list. I t is g i v e n h e r e t o f o r m a b a s i s f o r f u r t h e r documentation. Ranunculus repens (1) Creeping buttercup Ranunculus bulbosus (4) Bulbous buttercup Papaver rhoeus (4) Field poppy Chelidonium majus (2) Greater celandine Raphanus raphanistrum (2) Wild radish Capsella bursa-pastoris (4) Shepherd's purse Sisymbrium officinale (1) Hedge m u s t a r d Reseda luteola (1) Wild mignonette Melandrium dioicum (1) Red campion Melandrium album (2) White campion Cerastium fontanum (3) C o m m o n mouse-ear chickweed Stellaria media (8) C o m m o n chickweed Stellaria graminea (2) Lesser stitchwort Chenopodium album (3) Fat hen
Tilia europaea (1) C o m m o n lime Malva sylvestris (5) C o m m o n mallow Geranium dissectum (2) Cutleaved cranesbill Geranium pusillum (1) Small-flowered cranesbill Acer campestre (1) Maple Acer pseudoplatanus (2) Sycamore llex aquifolium (1) Holly Ulex europaeus (1) Gorse Sarothamnus scoparius (1) Broom Ononis repens (1) Restharrow Medicago sativa (1) Lucerne Rosa canina (2) D o g rose Crataegus monogyna (7) Hawthorn Epilobium hirsutum (1) Great willow-herb
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Chamaerion angustifolium (1) Rose bay Oenothera erythrosepala (1) Large evening primrose Hedera helix (4) Ivy Anthriscus sylvestris (7) Cow parsley Foeniculum vulgare (1) Fennel Pastinaca sativa (4) Wild parsnip Heracleum sphondylium (8) Hogweed Euphorbia helioscopia (1) Sun spurge Euphorbia peplus (1) Petty spurge Polygonum aviculare (6) Knotgrass Polygonum convolvulus (1) Black bindweed Rumex acetosella (1) Sheep's sorrel Rumex acetosa (1) C o m m o n sorrel Rumex crispus (7) Curled dock Urtica dioica (7) Stinging nettle Humulus lupulus (1) Hop Ulmus procera (5) C o m m o n elm Betula verrucosa (1) Silver birch Quercus robur (5) Oak Angallis arvensis (1) Scarlet pimpernel Fraxinus excelsior (4) Ash Myosotis arvensis (1) C o m m o n forget-me-not Melilotus alba (1) White melilot Trifolium pratense (2) Red clover Trifolium repens (7) White clover Trifolium campestre (5) H o p trefoil Lotus corniculatus (3) C o m m o n birdsfoot trefoil Vicia hirsuta (5) Hairy tare Vicia sepium (1) Bush vetch Vicia sativa (1) C o m m o n vetch
Lathyrus pratensis (2) Meadow pea Rubus fruticosus (5) Bramble Potentilla reptans (4) Creeping cinquefoil Agrimonia cupatoria (2) Agrimony Galium aparine (3) Goosegrass Galium mollugo (1) Hedge bedstraw Sambucus nigra (1) Eider Lonicera periclymenum (1) Honeysuckle Knautia arvensis (2) Field scabious Senecio jacobaea (4) C o m m o n ragwort Senecio vulgaris (7) Groundsel Tussilago farfara (1) Coltsfoot Filago germanica (1) C o m m o n cudweed Erigeron acris (1) Blue fleabane Conyza canadensis (1) Canadian fleabane Bellis perennis (2) Daisy Tripleurospermum maritimum (8) Scentless mayweed Matricaria matricarioides (4) Pineapple weed Achillea millefolium (11) Yarrow Chrysanthemum vulgare (5) Tansy Convolvulus arvensis (8) Field bindweed Calystegia sepium (2) Great bindweed Linaria vulgaris (2) C o m m o n toadflax Melampyrum pratense (1) C o m m o n cow-wheat Calamintha nepeta (1) Lesser catmint Prunella vulgaris (1) Selfheal Ballota nigra (5) Black horehound Lamium album (6) W h i t e dead nettle Glechoma hederacea (3) G r o u n d ivy Plantago major (6) Ratstail plantain
FLORA OF THE MARGINS
Plantago lanceolata (10) Ribwort plantain Plantago coronopus (1) Buckshorn plaintain Lapsana communis (5) Nipplewort Hypochoeris radicata (4) C o m m o n catsear Leontodon autumnalis (2) A u t u m n hawkbit Tragopogon pratense (2) Goatsbeard Sonchus oleraceous (2) Smooth sowthistle Sonchus asper (4) Prickly sowthistle Crepis vesicaria (2) Bealed Hawk's beard Taraxacum officinale (8) Dandelion Lolium perenne (3) Perennial rye-grass Poa annua (2) Annual meadow-grass Poa pratensis (3) Smooth meadow-grass Dactylis glomerata (7) Cocksfoot Cynosurus cristatus (1) Crested dogstail Bromus mollis (1) Soft b r o m e Agropyron repens (2) C o m m o n couch Hordeum murinum (3) Wall barley
Chrysanthemum leucanthemum Ox-eye daisy Artemisia vulgaris (7) Mugwort Arctium minus (4) Burdock Carduus crispus (4) Welted thistle Carduus nutans (2) M u s k thistle Cirsium vulgare (1) Spear thistle Cirsium arvense (9) Creeping thistle Centaurea scabiosa (1) Greater Knapweed Centaurea nigra (6) Hardhead Avena fatua (2) Wild Oat Festuca rubra (2) Red fescue Arrhenatherum elatius (6) False oat Holcus lanatus (5) Yorkshire fog Deschampsia flexuosa (3) T u f t e d hair-grass Pinus sylvestris (1) Scots pine Equisetum arvense (4) C o m m o n horsetail Pteridium aquilinum (2) Bracken
General conclusions 1. Variety of species: The number of species supported by the area of verge examined is at least 123. Of these about twenty are of general distribution, the others being found at only one or two of the sites examined. The number of species found at different sites is given in T A B L E 3. Chancellor (1969) lists sixty-nine species of weeds which are found in roadside verges around Oxford and Chelmsford. Of this sixty-nine well over half were found on Ipswich verges. Seventeen of the sixty-nine did not occur in Chelmsford and nine did not occur in Oxford. This indicates, as may be expected that verges in different counties may develop their own characteristic flora dependent on a complex interaction on many factors such as soil types and management. As indicated in T A B L E 1 the flora can change markedly between the verges on opposite sides of the carriageway as well as changing constantly along the length of the
Suffolk Natural History, Vol. 16, Part 3
carriageway. It is quite clear that verges can act as important reservoirs of wildlife, providing habitats for a wide rĂ¤nge of species. Most of these species are absent from the land adj acent to the carriageway. 2. Influence of adjacent land use: The presence of some species on the verges may be related to adjacent land use. For example sites bordered by arable contain some species which are characteristic weeds of arable land, e.g., Euphorbiapeplus and E. helioscopia, Anagallis arvensis, and Reseda luteola. Hedgerows also add variety, examples of species which appear to be mainly associated with the presence of hedgerows include Galium aparine and Melandrium dioicum. 3. Influence of soil and aspect: Reference to T A B L E S 1 and 2 shows how the flora of west and east verges are often quite different in character. The sandy west bank of site 2 supported a selection of heathland plants such as Rumex acetosella, Ulex europaeus, and Sarothamnus scoparius whereas the damp, well-shaded verge by Bentley Long Wood showed an abundance of Stellaria media and Glechoma hederacea which were less common at other sites.
Site 4 with its very sandy soil and south-facing banks has a wide variety of species not found at any of the other sites. These are listed under the description for site 4. Not all of the species are dependent on sandy soil and presumably many other factors determine their presence. 4. Width of verge: The width.of the verge is thought to have little if any effect. On very narrow verges six species are almost invariably present: Senecio vulgaris, Achillea tnillefolium, Trifolium repens, Taraxacum ofĂ&#x;cinale, and Plantago lanceolato, along with various grass species. Almost any species can turn up on narrow verges. Even large species such as Arctium minor and Centaurea scabiosa were found on the roadside edge of very narrow verges. 5. Influence of spray: The band of Vegetation six feet or more wide at the edge of the road is blackened by spray thrown up from the road by vehicles and is most conspicuous in the winter months. This spray will contain rubber particles, lead residues, salt, and mud. Apart from any toxic or osmotic effects the spray may have, it may perhaps cause a decrease in the photosynthetic rate. The dominant herbs of verges appear to tolerate the spray well. Two species, Matricaria matricarioides and Polygonum aviculare, were mainly found at verge edges probably because of a preference for disturbed areas rather than because of any effect of the spray. Tripleurospermum maritimum and Convolvulus arvensis were also more common on edges than elsewhere. Plantago coronopus found at site 1 is mainly a maritime species although its presence is not indicative of saline conditions. It occurs in a variety of inland sites
171 including between the paving stones of a churchyard in Ipswich and in sandy parts of the breck. It occurs at site 1 where vehicles pull into a layby. 6. Influenae of management: The seed mixture specified for use on these verges is Perennial Ryegrass S23, Red Fescue Ryegrass S59, Smooth-stalked Meadow-grass, Crested Dogstail, and White Clover S100. The verges are cut in May and July with a possibility of a third cut later depending on growing conditions. Only the lower two feet of the banks appears to be cut. There is a distinct change infloraof cut compared to uncut banks. Tall herbs such as Centaurea nigra, Heracleum sphondylium, and Cirsium arvense tend to be rare or absent on cut banks. The highest parts of uncut banks are being invaded by oak/hawthorn scrub or by gorse (sites 1 and 2). 7. Age of verges: It is difficult to determine the influence of the age of the verge on the variety of species supported as so many other factors have to be considered. As far as this study is concerned there is no correlation between age of verge and the variety of theflorabut none of the verges examined were younger than eight years and the oldest was only fifteen years old. 8. Special plants: No great rarities were discovered but some plants are rather local in distribution. The following are considered worthy of mention: Geranium pusillum is one of the slightly less frequent cranesbils. According to McClintock and Fitter (1955) Melandrium dioicum is a decreasing plant in East Anglia. Although it was nowhere common on the verges examined it is still a common plant on many of the verges of minor roads away from the AI 2. Conyza canadensis is a locally abundant plant in East Anglia especialy on disturbed ground. Erigeron acris is a locally frequent species in sandy soils. Calamintha nepeta is a very local plant of dry grassland especialy in East Anglia. The last three species were found amongst an interesting collection of plants at site 4, making this site of special interest and well worth preserving in its present State. 9. The verges as wildlife reserves: As mentioned in the previous section at least one of the sites is considered worth preserving for the variety of itsflora.Pierce and Ransom (1971) have pointed out that conservation of wildlife on roadside verges usually means a continuation of existing practices of management, the constancy of management leading to the establishment of stable plant communities. By 1971 eleven verges in East Suffolk and twentyeight in West Suffolk have been singled out for special management. Public pressure on roadside verges is generally small or nonexistent, except around laybys, and if properly managed the wildlife of the verges may be less disturbed than that of many FLORA OF THE MARGINS
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nature reserves. A footpath runs along the east verge of the AI 2 and enables people to enjoy the flora providing they can tolerate the disturbance created by the constant stream of traffic! References Chancellor, R. J. (1969). Road Vergesâ€”The agricultural significance of weeds and wild plants. Symposium on Road Verges, Monks Wood Experimental Station. McClintock, D . and Fitter, R. S. R. (1955). Collins Pocket Guide to Wild Flowers. Pierce, C. W . and Ranson, C. E. (1971). T h e Conservation of Roadside Verges in Suffolk. Suffolk Natural History 15, 376. Way, M . (1970). Wildlife on the Motorway. New Scientist, Sept., 1970.
W. J. Plurnb, Northgate Grammar School for Boys, Ipsivich.