Wetland
Water has sculpted the landscape for millions of years, creating a multitude of habitats which, in time have created a wide range of plant communities. Wetland habitats range from occasionally water-logged or seasonally inundated soils, to land seasonally submerged, to permanent bodies of water. Plant adaptations have evolved to deal with all of these, including rootless plants that float at the surface or live suspended in the water column. At the coast, plant communities develop that are salt tolerant, although few vascular plants are able to cope with full saltwater inundation and none occur in the open sea around our coasts. Strongly salt-influenced wetlands are covered under Coastal Habitats.
Although East Anglia has little in the way of major rivers, it has some of Britain's most important wetland habitats in the shape of the Fens and the Broads, both of which hold important populations of nationally rare plant species. Areas of open water range from a plethora of small farm ponds, many originating as flooded marl pits, through pits created by gravel extraction to extensive, man-made bodies of water created from peat diggings or as ornamental landscaping for some of the larger stately homes. Finally, the Norfolk/Suffolk border runs through a series of nationally important, species-rich, fen habitats.
Note: Wetland habitats can be fragile places and important plant communities are easily damaged by excessive trampling, especially valley mire and lowland fen habitats. Because of this, access to some wetland reserves mentioned below may be restricted. Please check accessability before entering any of the wetland sites mentioned here. In some cases, you may need to wait for a special open day and/or join a guided visit by the owners to see some of these special places.
1. Lowland Fens
'Fen' is a word that is used to define wetland habitats that develop in areas with a neutral to alkaline pH. Typically they are dominated by grasses and sedges and can vary in the diversity of associated plants from species-poor to species-rich. Fens may develop where there are springs or other reasonably reliable sources of standing ground water, as well as along the margins of rivers where the valley bottoms are broad. The huge expanse of land known as 'The Fens' in the west of our region has mostly been drained and converted to lowland grazing marsh, but some important areas remain and in recent years have been extensively improved with a view to recovering some of the lost ground. Fen habitat in Broadland is still quite extensive, especially along the Waveney/Little Ouse and River Ant wetlands and are especially species-rich with important populations of rare and uncommon plants, as well as other wildlife. Fen habitats along the Little Ouse (and to a smaller extent elsewhere in the region) are especially of interest as they have formed where chalky ground water flows through acid soils, creating unusual mosaics of fen and bog habitats; perhaps unsurprisingly, such places have interesting, species-rich plant communities as well as some rare invertebrates and other wildlife.
Fens are prone to drying out over time, mostly due to the accumulation of dead plant material caused as the vegetation dies down for the winter each year. Over time, this accumulation raises the soil profile above that of the natural water table and succession begins as alder and willow seedlings start to establish themselves. Drying fens can also become overwhelmed by strongly rhizomatous species such as Common Nettle. In fens that are protected and managed for their wildlife importance, mowing is an important management tool which helps to prevent the build up of dead plant material and the development of scrub.
 |
 |
| The flatlands of The Fens and Broadland with their vast skies are the epitomy of East Anglia according to many people's perceptions. Large areas of reedbed can dominate such sites but in areas of good quality, fresh water, these reed-dominated stands hold important tall herb fen communities which often include a number of nationally rare plant species. | Small areas of species-rich fen are frequent along the upper and middle reaches of several of our rivers and are typically dominated by open stands of Blunt-flowered Rush with just a thin scattering of Common Reed stems. |
 |
 |
| Within open stands of fen vegetation, many species of wetland plants form a rich community. | Old peat diggings and drainage attempts create deeper areas of open water. Over time, marginal vegetation can creep out across the water surface to create what often referred to as 'hover' - a fenland form of quaking bog. Where hover grows over the entire water body, dangerous conditions are created as deeper areas of water can be encountered unexpectedly. |
 |
 |
| The larger sedge species can form extensive stands (sedge beds) that compete well with Common Reed. Sedge beds can be species-poor but provide important habitats for some of our rarer wetlands birds and invertebrates. | If left uncut, sedge beds can gradually progress to wet scrub (carr). Where Great Fen-sedge grows in good quantity, it is cut during summer to provide products for thatching. In this species, the leaves are used to provide a more pliant material than the stems of reed and these leaves are used to round off the top of thatched roofs as well as to create thatch sculpturing. |
2. Valley Mires
Lowland valley mire is very similar to wetland habitats that develop in acid bog systems in upland areas but tends to be much more localised. These wetlands typically develop on sandy soils where heathland habitats dominate and, as such are rare in East Anglia, since much of our soils are neutral or chalky. Unlike fens, these plant communities tend to be poor in sedge species, though there are sedge relatives such as cottongrass that can be common. Plant communities of drier heathlands can form mosaics with small patches of valley mire, with Common Heather giving way to Cross-leaved Heath and more specialised wetland plants dominating in the wettest places.
The only valley mire of any size in East Anglia is at Dersingham Bog in West Norfolk. There are much smaller - but still important - patches elsewhere, but some are on private land so are not listed here.
 |
 |
| Small patches of valley mire can develop in larger fen habitats if calcareous ground water does not have too great an influence. Such spots can be rich in interesting plant species and are often given away later in the season by the white plumes of cottongrass. | Tussocks of Black Bog-rush and Purple Moor-grass provide less saturated ground for Cross-leaved Heath to become established while open patches of water between the tussocks are often populated by pondweeds. |
 |
 |
| Hummocks and mats of sphagnum moss in open areas can provide a home for carnivorous sundews. | At Dersingham Bog, large stands of Bog Asphodel light up the ground when in flower and can be easily viewed from a well-constructed boardwalk, that allows access without causing damage to the fragile structure of the mire. |
| Some Typical Species
|
Species to Look Out For
|
Places to Visit
|
3. Reedbeds
Linear stands of Common Reed form margins to many wetland habitats but perhaps the Somerset Levels and upper Humber Estuary are the only places in the UK that come close to the vast stands of reed that form extensive beds in East Anglia's wetlands. Much of the reed for thatching in the UK traditionally came from Norfolk and the plant has a strong cultural tie to the region, where it is often referred to as 'Norfolk Reed' in a way that implies it is a different species to that found elsewhere. While reedbeds are of vital importance for a small number of bird and invertebrate species, they are generally very species-poor when it comes to plants.
Common Reed may grow as an associate or co-dominant species in tall herb fens but forms almost pure stands closer to the coast where it tolerates a certain amount of saltwater. Along the coast and in the lower reaches of the main rivers it forms its largest stands, with the reedbed in the Hickling/Horsey/Martham area forming probably the largest contiguous stand of reed in the UK. Such coastal stands are particularly species-poor, with Common Celery often being the only broad-leaved flowering plant to be present in any quantity. Reedbeds are early successional habitats and most would quite quickly become willow scrub if not regularly managed.
 |
 |
| Extensive reebeds are common along much of the East Anglian coastline, especially in North Norfolk and East Suffolk, with the homogenous stands broken only by drainage ditches. | Seedheads of Common Reed last well into winter but eventually break down from weathering and will add to the dense layer of dead material or 'thatch' that builds up and suppresses other plant growth. |
| Some Typical Species
|
Species to Look Out For
|
Places to Visit
|
4. Eutrophic (Nutrient-rich) Lakes
There is no clear distinction between a pond and a lake, other than most people recognising that ponds are smaller bodies of water and lakes are larger! Here, lakes are recognised as being larger bodies that are of human origin and include gravel pits, lakes formed from former peat diggings (The Broads) and larger bodies of water created during the landscaping of stately homes, most often by damming existing water courses. Such lakes are typically rich in nutrients and are termed as eutrophic. Being rich in nutrients is not necessarily a bad thing, but higher levels of nutrient can result in high algal content, rendering the water green and opaque and often reducing the species richness of plants and higher animals.
Lakes can be highly variable in their plant communities depending on the water's depth and quality. Most are muddy-bottomed and have a range of plant species that may be marginal in their distribution, floating in the open water, or rooted in the bottom and extendng up to (or beyond) the surface. Many of the same plant species are also found in ponds, ditches and along the margins of rivers, which essentially offer the same or very similar growing conditions. Beyond the marginal communities, typically dominated by grass-like plants such as Common Reed, various sedges and rushes and the likes of bur-reeds and bulrushes, there can be extensive colonies of water-lilies at the surface, while the water column supports a range of pondweeds and waterweeds below the surface which may only be apparent by sampling with a grapple.
 |
 |
| The Norfolk Broads form an extensive network of eutrophic lakes amongst a landscape of reedbeds, alder and willow carr and other wetland habitats. Many of the broads themselves are difficult or impossible to access without a boat but its worth making the effort. | Lakes created as landscaping projects often have rather limited marginal pant communities, while gravel pits can be poor in plant species simply because they are too deep and their margins too steep to support much variety. |
 |
 |
| Smaller lakes can be more natural in appearance and often support richer plant communities around their margins. These communities may include both emergent plants that push up from the muddy bottom and sprawling species that are rooted in the bank but grow out across the water surface. | Relatively shallow lakes and large ponds often hold a rich community of submerged pondweeds and waterweeds and colonies of water-lilies. |
| Some Typical Species
|
Species to Look Out For
|
Places to Visit
|
5. Ponds
As commented above, there is no clearly agreed distinction between a lake and a pond other than a vague idea of size, though ponds more often tend to be isolated from permanent water sources such as rivers and streams and rely more on precipitation and groundwater. Here, ponds are generally considered to be rather small, relatively shallow bodies of water, with some drying out during the summer. In East Anglia, the landscape was once alive with ponds in the broader arable landscape, as they provided vital water for livestock. Some of these ponds may have been dug purposefully to provide water, especially on village greens and commons but many originated as marl pits which flooded once they were finished with. Natural ponds are found in coastal dune systems, where they are usually referred to as dune slacks.
Large numbers of ponds have been lost over time due to abandonment and they degrade quickly as they silt up or become overgrown with woody perennials such as sallows and, later, brambles. Projects to regenerate lost ponds (so-called ghost ponds in the landscape) have been remarkably successful in recent years and a number of plants not seen in East Anglia for very many years have reappeared from buried seedbanks. Village ponds are mostly degraded and often vastly overstocked with feral wildfowl, but some have been lovingly restored and can be exciting places to seek out plants (though beware that many will have introduced, non-natives amongst their flora).
 |
 |
| Larger ponds on common land are often abandoned and gradually develop ranker marginal plant communities. If surrounding land scrubs over, they can be overshadowed and then become rather species-poor. | Some watering holes for livestock often start as fenced off embayments from nearby water courses. If still used, low plant communities can develop around the margins, including species that favour bare mud caused by poaching from livestock. |
 |
 |
| Many ponds have disappeared under the plough over time but their presence is often given away by depressions in the ground that flood over winter. The bare ground can hold an interesting assemblage of plants that favour such open, damp places, especially members of the knotweed family. | Interesting restorative management schemes are returning a number of old farm and village ponds to their former glory. Such projects rely largely on removing years of bottom silt from the ponds and revealing hidden seedbanks. |
 |
 |
| Restored village ponds can be excellent wildlife havens and rich in plant species if well maintained. | Village pond restoration needs to be monitored closely to ensure that any introduced plants are appropriate. This pond in North Norfolk has become overwhelmed by New Zealand Pigmyweed, a highly invasive alien that is all too frequently dumped into waterways after it overruns garden ponds. |
 |
 |
| The location of overgrown ponds can often be detected so long as they remain wet enough to retain wetland plants. The location of an old pond on a grassy common is here indicated by the presence of Yellow Iris and Bogbean. | Dune slack habitats can produce interesting wetlnad plant communities that need to cope with periods of drying out in thr summer months. Pools such as these often survive in a healthy state as they are managed and maintained for rare amphibians (in this case, Natterjack Toads). |
6. Fluctuating Meres
This is a very rare habitat globally, so we are indeed blessed to have the only UK examples in Breckland. Fluctuating meres are lakes that are disconnected from any inflow source but instead receive their water directly from the underground aquifer. Aquifer levels rise and fall periodically but such fluctuations are not directly linked to precipitation so water level in these meres are always difficult to predict. The levels don't follow seasonality and meres can be full for several years then empty for several years with levels often changing remarkably quickly for no apparent reason. Six meres are identified as belonging to this unusual water system, with Langmere at East Wretham, Norfolk being by far the largest.
I have also included here the pingos of Breckland as their water levels behave unpredictably in the same way, with short or long periods of wet and dry conditions occurring at irregular intervals. Pingos form during periglacial periods, when water below ground can freeze. As the water freezes, expanding ice pushes outwards and upwards, creating small hillocks. During periods of thaw, the hillock collapses, leaving a depression in the ground where the ice once sat. Over 400 pingos are known in the Breckland region with the best examples providing a home to a diverse range of unusual flora and fauna. Despite extended dry periods, both pingos and true fluctuating meres can hold interesting communities of pondweeds.
 |
 |
| A rich community of aquatic plants in a pingo during one of its wet phases, including a good diversity of sedges and a dense surface layer of pondweed. | The same pingo a year later as it enters one of its dry periods. The vegetation looks mostly dead with just a single tussock of sedge sitting out in the middle, but this is a natural event and a wetland plant community will develop again once water returns. |
 |
 |
| The same pingo as in the upper two photos during a different wet period. In this period, Fine-leaved Water-dropwort has produced a flowering ring of white around the margins. | Langmere, largest of the Breckland fluctuating meres, at full water. |
| Some Typical Species
|
Species to Look Out For
|
Places to Visit
|
7. Brackish Lakes
These are lakes where the water can best be described as a mixture of fresh and brackish water. Such lakes are rather scarce as permament or long-term features of the landscape but the wetland complex formed by Hickling, Horsey and Martham Broads falls into this category. Saltwater creep occurs along the main waterways, reaching its upper limits in this watershed. Plant species adapted to this habitat are relatively few, with species richness being low close to the open water, but increasing further back up the gradient as freshwater becomes more dominant. Common Reed forms extensive stands around brackish lakes, but the subaquatic flora can be surprisingly interesting and includes the nationally rare Holly-leaved Naiad.
 |
 |
| At 1.4 square kilometres, Hickling is the largest of the Broads and one of a group of low-lying waterbodies that receive saltwater incursion, rendering them brackish. Despite its size, Hickling Broad is difficult to view from dry land and get become lost amid a great sea of reedbeds. | Hickling Broad's brackish waters are mostly only around 1.5 metres in depth and support the largest population of the nationally rare Holly-leaved Naiad in the country. |
 |
 |
| Brackish waterways can occur near the coast wherever there is a chance for saltwater incursion into what would otherwsie be freshwater features. Some such ponds can fluctuate in their salinity, depending on recent levels of precipitation versus any recent saltwater creep. Such ponds develop interesting plant communities that need to adapt to these fluctuations in order to survive. | Sea level rise and consequent coastal erosion is increasing saltwater inundation in coastal freshwater habitats during winter storm events. Increasing saltwater content will greatly reduce the range of plant species that can survive here and may eventually even become saltmarsh. |
| Some Typical Species
|
Species to Look Out For
|
Places to Visit
|
8. Ditches and Dykes
By their very nature, these are linear and often narrow habitats. Ditches and dykes are cut through wetlands and arable farm areas to draw water from the land. In arable areas, ditches can spend a lot of their time dry or at the very most, filled with damp mud. Such ditches typically contain assemblages of plants similar to those on the surrounding ground, though the increased dampness often promotes taller growth and a rather rank community of rhizomatous species such as Common Nettle and Great Willowherb can dominate. Here, I have not included plant species of the driest ditches since such ditches are really simply artificial banks, but can be very good for plants, especially on the boulder clay where they often represent relics of former woodland habitats with Primroses, Dog's Mercury, dog violets and the like.
Dykes tend to be more permanently wet and often criss-cross areas of wetland in low lying regions such as the Broads, Fens and coastal grazing marshes. These are effectively long, narrow lakes, often holding quite deep water and rich in aquatic plant communities, including some uncommon and rare species such as Water-soldier, bladderworts and Fen Ragwort. Coastal dykes include main drainage channels, borrow dykes and the like and are often brackish or even saline. These are good places to look for coastal plant species such as Sea Club-rush and tasselweeds.
 |
 |
| Ditches and dykes that are permanently wet (or more or less so) effectively serve as linear ponds or lakes. They may be connected to main waterways, or isolated by sluices or dxrainage valves and this can affect the plant communities that develop. Here, a colony of Mare's-tail is extending across the waterway. | Colonies of emergent vegetation often develop over time, spreading out from the bank and eventually filling the channel which may then need periodic dredging to function as intended. A wide mix of plant species can develop, including Floweing Rush, water-plantains and bur-reeds. |
 |
 |
| In more arable areas, ditches may be only periodically wet (typically during the winter). Plant communities in these muddier habitats are often dominated by Great Willowherb, Common Nettle and Branched Bur-reed. | Species-rich aquatic plant communities can develop in permanent dykes in low-lying regions in the Fens and Broads. This can include some nationally scarce species such as (as here) Water-soldier. |
 |
 |
| Coastal dykes are often brackish and the margins typically develop dense stands of Sea Club-rush. Few subaquatics tolerate the salinity, but tasselweeds and Fennel-leaved Pondweed can be present in good quantity if the water is clear. | High nutrient levels, usually occurring through run-off from agricultural areas, can degrade water quality and floating colonies of Enteromorpha and other algae can dominate, reducing or even eliminating subaquatic plant communities. |
9. Slow Rivers and Streams
In a largely flat landscape, East Anglian rivers are mostly rather slow-moving and are typical of rivers in their middle and lower reaches. Such rivers readily form meanders which create areas of shallow water with muddy bottoms and these provide ample opportunity for wetland plant communities to develop. In the largely anthropic habitats that dominate much of East Anglia, many of our rivers have been altered over time, with water courses straightened in efforts to move water more quickly through the landscape for drainage purposes. More recently, it has been realised that this does not produce the desired results and conservation projects are returning many rivers to their original watercourses, with a consequent return of richer plant communities. In their lower reaches, the larger rivers broaden out and human activities reduce plant communities through dredging to maintain navigation channels.
Defining streams from ditches and dykes is not easy, but streams are typically more akin to small rivers, following meandering courses and being more natural in their origins. Plant communities that develop can be influenced by the habitats around the water course. Streams running through woodland are more deeply shaded and often more or less devoid of aquatic vegetation, instead have marginal communities of shade-tolerant sedges, grasses and woody species such as Red Currant.
Navigation canals would come under this heading, but East Anglia has few of these and none still functioning as fully navigable. East Anglia would appear to be perfect territory for developing a canal system but, aside from canalised channels in the Fens (which were largely cut for drainage rather than navigation), the only navigable canal is the old North Walsham & Dilham Canal, cut to allow water-borne passage from the Broadland river system to North Walsham.
 |
 |
| Lowland rivers are often made navigable for commerce or pleasure and this can greatly limit the plant communities that can become established. The navigable channel is regularly dredged, while the banks are made secure with woodwork or concrete. | Where left more natural, a wide range of wetland plant communities can develop, both along the river margins and subaquatically, such as along the River Wensum in the heart of Norwich. |
 |
 |
| A meander in a slow river allows sediment to settle out on the inside of the curve, providing bare mud that will be colonised in time by new plant communities. | Slow-moving rivers that are not regularly dredged can develop complex channel systems and mudbanks, the latter allowing emergent vegetation to grow out in the main waterway, providing undisturbed 'islands' for riparian wildlife. |
 |
 |
| Streams and abandoned canals are often colonised by extensive sedge beds, especially in more enclosed or shaded sections where Common Reed tends not to become established. | Abandoned canals offer opportunities for species that do well on harder substrates and which would otherwise be overwhelmed by more aggresive species. Damp brickwork provides a home to a range of mosses and liverworts as well as vascular plants and such places can hold unusual plant communities. |
| Some Typical Species
|
Species to Look Out For
|
Places to Visit
|
10. Faster Rivers and Streams
Faster moving rivers and streams are not a common feature of East Anglia because of the lack of steep gradients in the landscape, but there are a few stronger currents in our region. Faster moving water tends to prevent sediment settling and the bottoms of such water bodies are, as a result, usually more solid and stony. In such situations, fewer plants become established in the water itself, but those that do are more specialised and thus more interesting and unusual in a local context. The banks of these waterways are more stable than the main channel and typically have plant communities that would also be seen along slower moving rivers.
 |
 |
| Stretches of the Little Ouse through Breckland have cut down close to the bedrock and run freely over gravelly bottoms. In the summer, these sections are studded with the starry white flowers of water-crowfoots, whose stems grow to several metres long in such places. | Submerged populations of water-starworts are common in faster moving rivers, such as here in the Stiffkey River, North Norfolk. |
 |
 |
| With a lack of sediment, faster rivers run much clearer and allow the botanist to view the range of subaquatic species that proliferate in such clear conditions. | The River Wensum at Ringland runs clear over a stony substrate and is populated with large colonies of waterweed and pondweed species. |
| Some Typical Species
|
Species to Look Out For
|
Places to Visit
|