Coastal Communities
Plant communities that come under the coastal habitats heading are very varied, since they are not defined by a particular group of plants (such as grasses for grassland or trees for woodland) but are defined by their close proximity to the sea. However, there are at least some limiting factors which affect the development of plant communities; plants need to be salt tolerant and many of them need to be tolerant of shifting substrates since the effects of tide activity and wind make these habitats often very volatile.
This section covers a wide range of habitats that may be found at the coast, from estuaries and shingle beaches to saltmarsh. There are also harder landscapes such as sea cliffs and coastal defence structures with their own, unique communities of plants. Note that coastal grazing marshes, which have often been created through draining and conversion of saltmarshes, are covered under the grassland communities, while salt-influenced wetlands within reclaimed grasslands are covered under the wetland communities.
1. Mudflats and Sandflats
Coastal areas of land that receive the greatest number of saltwater inundations from tidal movements often have very few plant species growing on them. This is partly because the substrate can be highly mobile at times of high water activity - especially during stormy conditions - and partly because only a small number of plant species have evolved that can tolerate the high salt content in the water. Where rivers constantly bring sediment along their courses to the coast, the estuaries tend to be mud-dominated, such as at The Wash and Breydon Water in Norfolk and along most of the tidal sections of the Suffolk and Essex rivers. Along the North Norfolk coast, longshore drift of fine particulates westward, produces areas that also have sand bars, such as in the estuarine regions behind Blakeney Point and Scolt Head.
At the lowest level, where the mud or sand is only exposed at the lowest spring tides each month, can be found the eelgrasses, sometimes forming seaweed-like mats (remember that true seaweeds are algae, not plants). On the lowest open flats between the tidal creeks, a scattered and open community of plants consisting solely of various glasswort species develops, forming the low saltmarsh communities, while colonies of Common Cord-grass creep out and begin the initial stabilisation of sediment around their roots. This build up of sediment will eventually lead to slightly higher and more stable ground and which will provide areas for the development of mid saltmarsh communities. Because the development of these communities is largely governed by water inundation, the communities themselves can form very distinct, stratified zones within the overal coastal habitats.
Note: Mudflats and sandflats can be very unstable and potentially dangerous places. Exploring them is best done with assistance from someone with good local knowledge of the terrain.
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| At the lowest spring tides each month, eelgrass can be found in a few places in the lowest intertidal zone. Eelgrass populations have been decimated by a protistid slime mould disease and continue to be threatened by climate change and pollution. These aquatic plants are now generally rare and only found in a handful of estuaries in our region. | Mud and sand flats can look barren at low tide. Here, a scattering of glassworts grow to the right of the creek and a colony of Common Cord-grass is encroaching from the left. |
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| Bright green stands of glasswort (collected and eaten locally as 'samphire') colonise muddy areas during the summer and form the bulk of lower saltmarsh plant communities. Most of the species are annual, germinating in late spring/early summer and dying away in the autumn. | Where there is a firmer substrate beneath shallow mud, on 'hards' and shingle banks, Perennial Glasswort often forms tight tussocks between the more open mud and the start of more species-rich, mid saltmarsh. |
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| By far the commonest of our glassworts is Purple Glasswort, which turns a distinctive purple colour as it starts to die down in the autumn. |
| Some Typical Species
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Species to Look Out For
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Places to Visit
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2. Saltmarshes
Large areas of our coastline support interesting and complex saltmarsh plant communities. These communities develop on a range of substrates and over a range of intertidal habitats but can be broken out into three main zones - low, mid and upper saltmarsh. Low saltmarsh develops on mud and sand flats and is described above. Mid saltmarsh is perhaps the most interesting of the saltmarsh zones; it develops on ground receiving the mid to least amount of saltwater inundation and the plant species present can vary according to the solidity of the substrate and subtle variations in flooding. Typically the lowest locations remain very wet throughout, even forming lagoons in the saltmarsh (see below). Slightly above these, large areas are dominated by a mosaic of plants, typically including Common Saltmarsh-grass Common sea-lavender, Sea Aster, Thrift, Purple Glasswort and Annual Sea-blite among others. Where sediment settles out along the edges of creeks, small levees naturally develop and are mostly colonised by Common Sea-purslane which forms distinctive ribbons of glaucous vegetation that snake through the marsh.
Upper saltmarsh develops at the upper end of the inundated zone, typically only receiving flooding on the highest spring tides. This zone usually occurs on a harder substrate (because less sediment gets deposited here) and the plant communities are often dominated by Common Sea-purslane, Red Fescue and Sea Couch. Thrift and Sea Wormwood typically occur here and, in some estuarine systems, distinctive stands of Shrubby Sea-blite occur while in others, Golden-samphire grows. Upper saltmarsh often has a highwater strandline which can consist of great quantities of plant debris from species that die down in the winter. This strandline can consequently be nutrient-rich and, by late summer, typically has a plant community containing various goosefoots, oraches, Sea Beet and Annual Sea-blite.
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| Mid saltmarsh typically consists of a complex mosaic of plant zones according to substrate and saltwater inundations. This mosaic can be seen in the different colours of the various plant communities present, especially when some of the more showy species are in flower in mid to late summer. | Mid saltmarsh zonation is easily seen here in the grey-green strips of Common Sea-purslane that run along the creek levees. Stands of Common Sea-lavender and Sea Aster dominate the flat areas in between the creeks. |
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| In late July and early August, mid saltmarsh can be a riot of colour where Common Sea-lavender dominates. | A typical upper saltmarsh zone. Here, Common Saltmarsh-grass gives way to Sea Couch and there are good stands of Sea Wormwood. The latter can also be frequent along levees with Common Sea-purslane. |
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| Upper saltmarsh strandline communities can form where floating debris is left by the highest spring tides. Sea Beet can be common here and, in this picture, a belt of bluish Sea Couch can be seen behind. | Shrubby Sea-blite forming a narrow zone at the top of the saltmarsh and the bottom of an artifical sea wall. |
3. Strandline Communities
To avert any confusion, there are different names in different regions for what I have termed a strandline. In some regions, the term strandline is used to define the higher part of a beach, above that of normal high tides. Here I use it to define the line of debris left along the beach front after the tide turns. In some areas, this band of debris is referred to as the wrackline, because much of it consists of fragments of various seaweeds known as wrack. As organic material from the strandline breaks down, it produces a more nutrient-rich strip on the beach into which floating seeds of coastal plants also get deposited. Strandlines can be very fragmented and can be rather transitory, easily washed away by storms. A wide range of species can occasionally occur as isolated individuals along the strandline, but some species particularly thrive here, especially Annual Sea-blite, Prickly saltwort and certain oraches. Annuals tend to fair better than perennials in strandline plant communities due to the transitory nature of the habitat.
Strandline communities do better on sandy beaches which tend to be more stable than shingle, perhaps because the larger particle size of shingle are more easily disturbed and harder for plants to root into.
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| A typical strandline community on an open, sandy beach at Blakeney Point, Norfolk, at the interface with the rising dune line behind. Frosted Orache and Prickly Saltwort are common here. | A strandline community at the base of a soil bank on the side of an estuary. Here, colonies of the deeper-rooted, perennial, Sea Sandwort are also becoming established amongst the oraches and Sea Rocket. |
| Some Typical Species
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Species to Look Out For | Places to Visit
to look for strandline communities |
4. Sand Dunes
As is the case with saltmarshes, sand dunes have complex plant communities that form mosaics with each other according to the stability of the substrate and the age of the dunes. These dune communities typically form three broad zones; nearest to the open sea or beach, the sand is usually most mobile due to wave and wind action, especially the latter. These youngest of dunes thus tend to hold the fewest plant species and often consist of pioneer Marram stands with short term colonies of annual strandline species. The presence of Marram is critical to the development of the dunes since the marram traps and holds wind blown sand particles in the first step towards proper dune formation.
With greater stability, species such as Sand Sedge, Sea Bindweed and Sea Sandwort take hold and further stabilise the sand, while increasing amounts of organic material allow more nutrients to build up. Mid-aged dunes are typically still dominated by Marram but have a much greater number of plant associates. Eventually, older dunes which, by their nature, are further from the beach and any mobile sand debris, settle down and stability is further aided by a more complete cover of vegetation. Mature dunes can, over time, develop rich and complex lichen communities while the typically acidic nature of the sand means that heath communities can develop. Where there is an underlying layer of less porous soil, water can build up over winter in hollows between the dunes. These areas are known as dune slacks and can hold interesting plant communities, often with uncommon or rare species present.
To preserve important land inland of the dunes, some dunes have been planted up with trees - typically conifers - over time. Though these dune woodlands are artifical in origin, they nevertheless can develop very interesting plant communities, especially where water is retained for at least some of the year. Extensive dune systems occur along sandier sections of coast and are best developed in North Norfolk and north of Great Yarmouth.
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| Pioneer sand dune developing with the assistance of European Marram. Note the finer, wind-blown sand particles collecting around the marram shoots, compared with the heavier particles in the more open spaces. | Pioneer dunes can reach over 15m in height before they settle down into middle age and more species-rich plant communities develop. Sand Sedge often colonises large areas of mid-aged dunes while species such as Carline Thistle, Blue Fleabane and Pyramidal Orchid can be plentiful. |
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| Mid-aged dunes with a good range of plant species, including stands of Common Polypody. | As dunes mature, scrub and tree cover can sometimes develop, depending on seed availability from neighbouring land. Typically, brambles, roses and Common Hawthorn appear, but birches can also encroach if there is heathland nearby, pines self-seed where planted nearby and local specialities can include sea-buckthorn. |
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| The full suite of sand dune systems is particularly well-developed at Winterton-on-sea, Norfolk. Here, Nationally important colonies of Grey Hair-grass dominat in places, Royal-ferns grow in the dune slacks and the dunes interface nicely with neighbouring heath plant communities. | In wetter hollows, dune slack communities can develop, with a number of orchid species as well as some rarities such as Jersey Cudweed. Scrub in such places is often dominated by sallows and the vegetation is overall greener and more lush. |
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| Plantations of pine on dunes in North Norfolk produce an unusual set of plant communities in the more shady and sheltered conditions. The shrub layer includes much self-seeded Holm Oak and European Holly, while the ground layer has some major local rarities, including Creeping Lady's-tresses and Yellow Bird's-nest. | Fully stabilised, older dunes can develop a thick ground layer, that is particularly rich in lichens and mosses as well as higher plants. |
| Some Typical Species
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Species to Look Out For
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Places to Visit
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5. Coastal Vegetated Shingle
In East Anglia there are Nationally important areas of coastal shingle forming significant beaches and spits of great size. In particular, the shingle ridge that runs from Weybourne in Norfolk, west to Blakeney Point and the spit of shingle that runs south to form Orfordness in Suffolk. These sites have very interesting floras, but coastal plants can be found on other areas of shingle, too. Shingle beaches are highly mobile due to the action of waves, thus plants need to be able to cope with this to survive. Shingle beach plants tend either to be annual, turning their life cycle around quickly during the relatively calm summer months, or they are very deep-rooted perennials, the deep roots serving to anchor the plant in place as best they can. Species such as Common Sea-kale, Sea Pea, Sea Campion, Sea Sandwort and Yellow Horned-poppy favour these environments.
Where shingle areas at the coast have become stabilised, a very interesting coastal short-turf community of plants can develop. Indeed, these short-turf communities can also develop on other coastal areas such as clifftops and along the landward edge of stabilised dunes. These well-developed plant communities are rather different from those of more exposed and mobile shingle areas and usually include a good range of clovers, mouse-ears, crane's-bills and other low-growing species.
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| After scouring by winter storms, shingle beaches can look rather barren, but deep-rooted perennials will eventually push back through, while wind-blown seeds of annual species will eventually settle and germinate. | By high summer, perennial Sea Sandwort, Sea Campion and Yellow Horned-poppy have here pushed up and started to flower. These species are often accompanied by a strandline plant community if winter tides have surged high enough up the beach. |
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| Shingle beaches along the Suffolk coast host Nationally important populations of Common Sea-kale and Sea Pea. | Common Sea-kale populating a Suffolk shingle ridge. |
6. Saltmarsh Lagoons
Within areas of mid saltmarsh, softer ground often gets scoured out and the resultant lower patches of ground can be more or less permanently flooded with salt water. Such locations are typically species-poor when it comes to plants, but a simple plant community of brackish or saltwater aquatics can develop, largely consisting of such species as Fennel Pondweed and the tasselweeds. Brackish lagoons and other waterbodies that may be present on the landward side of sea walls within grazing marshes, are covered under the wetland communities.
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| More or less permanent pools within mid saltmarsh areas can provide places for certain pondweeds and tasselweeds. If they dry out periodically, they often become colonised by glassworts. |
| Some Typical Species
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Species to Look Out For
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Places to Visit
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7. Sea Walls and Defences
The entire East Anglian coastline has, at some point, undergone significant change as efforts have been made to hold back coastal erosion and to even create new, manageable land from saltmarsh (so-called 'land reclamation'). In most cases, these efforts have consisted of the creation of soil banks or walls, constructed from clayey subsoils that resist water permeation. From a natural landscapes viewpoint, this has resulted in the complete loss of a natural progression of habitats and their associated plant communities as saltwater areas are abruptly cut off from freshwater marshes. In effect, these banks do not fully support coastal plant communities and are best considered grasslands, but they are included here as they are an integral part of the coastal landscape.
Generally, these sea walls are colonised by grassland communities, typically dominated by a handful of coarser species such as False Oat-grass and Perennial Rye-grass and, indeed, repairs or reworking of the banks are usually reseeded with grass after work is completed. In many places, larger plant species such as Common Nettle, Black Mustard and several umbellifer species become established, while species such as Common Reed spread in from neighbouring land. In a few locations, particularly in the lowest, most salt-inundated soils towards the coast in Broadland, a few interesting species such as Narrow-leaved Bird's-foot-trefoil and Slender Hare's-ear can be found in shorter turf on the sea walls.
In areas of greater pressure from coastal erosion, concrete or stone structures are built. Although these are limited in their plant communities, they do occasionally offer a substrate for species that would otherwise be unlikley to be present. Most of the plant species of these constructions tend to be ephemerals and annuals of urban habitats and disturbed ground, but a few speies that typically favour rocky habitats that do not naturally occur in East Anglia can sometimes also be found, such as Rock-samphire.
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| Grass-covered banks are a common feature around East Anglia's low-lying coastline, with open saltmarsh to the seaward side and managed (usually grazing) land to the landward side. The rather dense, clay-based soils of these banks tends to mean they get colonised by a relatively small number of tougher perennial species. | Concrete or stone coastal defence structures are limited in what they offer as opportunities for plants. But more open designs provide soil-filled recesses that are soon populated by a range of plant species, including those that often colonise shingle beaches. |
| Some Typical Species
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Species to Look Out For
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Places to Visit
sort can be found along almost the entire coastline and well inland along tidal rivers in The Broads and along the main Suffolk and Northeast Essex rivers. |
8. Cliffs
Whilst East Anglia's landscape - especially its coastline - is notoriously flat, there are places where the land rises high enough to create a series of low cliffs and bluffs. These occur in the Northwest of the region at Hunstanton; from Weybourne to Happisburgh in Norfolk and as a series of irregular outcrops from Winterton-on-sea, Norfolk, southward to Southwold, Suffolk. Scattered, smaller, river bluffs also occur further south, such as at Bawdsey and Felixstowe in Suffolk and Harwich in Essex. Hunstanton's cliffs are a local anomaly, being hard cliffs, formed from an outcrop of underlying chalk and carstone. The more or less vertical face provides little habitat for plants and narrow ledges are colonised by grassland species that frequent the area above the cliffs.
In contrast to Hunstanton, the rest of the coastal cliffs consist of eroded glacial till which has no stratification and is typically little more than loose sand, clay, flint and chalk. Erosion of these cliffs takes place when ground water pushes out lower down the cliff, causing the top not to topple over but to collapse. The resulting slumps are then gradually eroded away by successive high tides. In many places, the result of this activity is to create a series of slumped mounds and hollows with wetter areas where there is more clay or where ground water percolates out on a regular basis. Recent slumps are bare, but they gradually become colonised by grasses and may even scrub over with Hawthorn, Blackthorn and Gorse. More settled areas have developed some interesting plant communities, especially in Northeast Norfolk where huge colonies of Common Kidney-vetch occur as well as good colonies of several orchid species.
Note: Cliffs can be very unstable and potentially dangerous places. Exploring them is best done with assistance from someone with good local knowledge of the terrain.
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| Hunstanton's cliffs consist of a deep layer of white chalk, then a layer of iron-rich 'red chalk' and ochre-coloured carstone beneath. | Recent cliff slumps at Sidestrand, Norfolk, before plant colonisation has begun. Such areas are extremely unstable with saturated clays often behaving like quicksand and a dangerous trap for the unwary. |
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| A recent cliff slump, showing a wet 'toe' pushing out across the beach at low tide. Sea-buckthorn scrub and coastal turf plant communities now find themselves almost on the beach and will eventually be eroded away by successive tides. Some colonies of rare or endangered species are similarly threatened in this way. | Colonisation by grassland plant communities can be quite rapid if conditions are right. Such areas hold species-rich turf communities, often with several orchid species and a good range of other species. |
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| This steep section of slumped cliff at Mundesley, Norfolk has developed an impressive cover of Common Kidney-vetch. | Here, an interesting mix of plant communities has developed on an area that has not been eroded for some time. Mixed shrub communities have become established, while water lying over clay is permanent enough for stands of Common Reed and Common Bulrush to thrive. |
| Some Typical Species
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Species to Look Out For
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Places to Visit
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