Wet woodland

Woodland habitats are dominated by trees which are more than five metres high when mature. The trees form a canopy, sometimes with as little as 30% continuous woodland cover. Many woodlands in Britain are stunning places. Our ancient woodlands are a sight to behold in spring with their carpets of bluebells. Woodlands also played an important role in our history, providing food, shelter and fuel, whilst woodlands near water played a crucial role in the shipping and iron industries.

Although UK woodlands have doubled in area since World War II, most of these woodlands are new plantations of non-native trees, and the UK remains far less naturally wooded than many other European countries in similar climatic belts. Around 46% of ancient woodland has also been converted to plantation or agriculture since 1946.

In Sussex we have a lot of woodland relative to the UK average, and the Weald has the greatest cover of woodland in Britain. Woodland and forests over 2 ha in size cover roughly 18 % of Sussex (over 69,000 ha - FC data), and with smaller woodlands included this area becomes significantly larger. Ancient semi-natural woodlands (ASNW - or woodlands which have stood for over 400 years) cover about 11 % of Sussex (or just under 43,000 ha). Sussex on the whole contains a number of large ancient woodland complexes, the West Weald and High Weald are of most note. Woodlands are increasingly being looked to as a means of storing carbon to manage climate change and storing water to manage flood risk.

There are a wide range of woodland types in Sussex, but some of the rarest are our wet woodlands. The three ‘wettest’ types of woodland are described below :-

Floodplain woodland

These woodlands are found in river floodplains. Floodplain woodlands are highly dynamic (frequently changing). They often have a complex mosaic of wet and dry habitats, each with distinct communities of flora and fauna. This habitat depends on continual natural disturbances including erosion, flooding, deposition and changes in river channels. With their natural dynamism, they by no means have complete canopy cover, and in fact tend to have numerous open areas caused by natural tree fall and flood action.

Floodplain woodlands are scattered across Sussex but they tend to be found higher up our river catchments where rivers have been less engineered. They are often in small patches on alluvial soils alongside streams, but can be more extensive if they occur lower down the river. In Sussex, most of our floodplain woodlands are small and isolated fragments of secondary or semi-natural and ancient woodlands.

There is currently around 570 ha of deciduous woodland in the main flood zones of Sussex, of which less than 300 ha is ancient woodland. Ancient floodplain woodlands are therefore a very rare Sussex woodland habitat. There are around twenty floodplain woodlands in Sussex of over 5 ha in size, and only eight over 10 ha. The majority of Sussex floodplain woodlands are linear in nature and occur in narrow floodplains. In our major floodplains, naturally flooding/functioning floodplain woodlands are effectively extinct, although a few fragments occur along the coast.

The Black poplar (ssp betulifolia) is the rarest native wetland tree in Sussex. It now exists as scattered, planted individuals rather than naturally as part of a woodland type. It is likely that the floodplain woodland habitat in which Black poplar would have been present is extinct in Sussex, although woodlands classed today as W6 - woodland of nutrient rich alluvial valleys are close.

Wet woodland

These damp and boggy woodlands can be found where land features such as hollows combine with hydrological features such as springs, and geological features such as impermeable soils, to create lenses of woodland in areas of wet soils. They tend to be found away from lowland floodplains and are characterised by the presence of alder, birch and willow. They rely more on natural springs and seeps to maintain their ‘wet’ character.

Wet woodlands tend to occur in scattered patches across the higher landscapes of Sussex. They are found on impermeable soils and bedrock such as the Wealden clays and they are sometimes influenced by other human sources of water such as surface run-off and drainage. Wet woodlands also develop at the upstream end of man-made ‘on-line’ lakes and ponds where siltation allows succession to take place. Some of our largest wet woodlands in Sussex occur in these locations.

There is limited information on the distribution and area of wet woodlands in Sussex and further mapping and research is required. Of the ancient woodland area in Sussex, around 1,600 ha is found on naturally wet soils, and 14,500 ha on soils with impeded drainage. This implies that a significant proportion of the Sussex ancient woodland resource (around 38 %) could be wet woodland habitat with wetland interest.

Ghyll woodland

Due to their isolation and enclosed nature, Ghylls have a unique microclimate, often rich in bryophytes and other moisture loving plant species. Ghyll woodlands are found in the extreme upper reaches of rivers, where springs and streams first form in small, steep, wooded valleys. The steep sided nature of Ghyll’s has also ensured that many Ghyll woodlands have remained untouched and undisturbed by human activity. Ghyll woodlands have an unusual micro-climate and they are therefore unique.

The flora found in these sites is very characteristic of former Atlantic conditions - including lush growths of ferns (such as hay scented buckler fern), mosses and liverworts. Many are likely to be primary woodland sites (potentially dating from the ice-age) and some have received relatively little disturbance, pollution or management. Ghyll’s provide an important function within the wider river catchment. They help to capture and slow down rainfall and overland run-off which would otherwise have a high capacity for erosion in these steep areas. They also provide shade and protection from sunlight, which provides a kind of ‘thermostatic regulation’ to downstream areas of river by cooling down water temperatures. Cool river temperatures are particularly important for the reproduction of a number of fish species.

Over 6% of the High Weald in Sussex is classed as ‘Ghyll’ woodland. This rare habitat type is a unique landscape feature of this part of Sussex and of the UK. Ghyll woodland in these terms specifically applies to the woodland found in the Sandstone and Hastings beds of the High Weald. There is currently no agreed definition of the riverine/floodplain limits at which Ghyll woodland becomes a floodplain woodland, and as such it is difficult to assign an accurate figure to the known area of Wealden and non Wealden Ghyll woodlands in Sussex.

Other rare wet woodland types

There are many more (wooded) headstreams in Sussex which run through steep sided valleys with unique geology and ecology. Streams in the Wealden greensand ridge run across north and west Sussex, and those found in Sussex heathlands are also likely to possess unique wetland characteristics. Rare acid wet woodlands such as Broadwater Warren and rare chalk spring fed wet woodlands such as those found at Bosham and Nursted, contribute to the value of the wetland network in Sussex and are uniquely rare. As yet these (wooded) headstream characteristics are poorly described, mapped or surveyed.

Species you might find in the wet woodland habitats of Sussex

There are a huge range of woodland, wetland and specialist species to be found in the wet woody areas of Sussex. Some of these are more characteristic of ancient woodlands, and others are defined by climate, soil and geology. Some of the more unusual species that you might see include :-

  • otter (Lutra lutra)
  • greater tussock-sedge (Carex paniculata)
  • water Avens (Geum rivale)
  • wood horsetail (Equisetum sylvaticum)
  • beech fern (Phegopteris connectilis)
  • Epiterygium tozeri (a rare moss)
  • Lecanora jamesii (a lichen)
  • Pellia epiphylla (a liverwort)
  • willow tit (Poecile montanus)
  • common crane (Grus grus)

For more information on woodland grants see :-

The Forestry Commission andThe Woodland Trust

Or for more information on wet woodlands download our leaflet on How to create and restore wet woodland.