Now in its 24th year, 2 February is World Wetlands Day (WWD) – an opportunity to raise global awareness about the vital role of wetlands for people and our planet.
This year WWD focuses on wetlands as a source of freshwater and encourages actions to restore them and stop their loss. It’s also a chance to learn about some of the special wetland habitats found across the High Weald Area of Outstanding Natural Beauty. Sarah Brotherton, Landscape Officer and newest member of the High Weald AONB team (right), takes a closer look...
What are wetlands?
Wetlands are a broad category of dynamic and productive ecosystems straddling aquatic (water) and terrestrial (land-based) environments, with water levels either permanently or cyclically at ground level or above. Water is the controlling factor on both plants and animals, resulting in many specialist species that have adapted to these ecosystems over thousands of years.
Wetland habitats range from coastal salt marshes, lagoons and mangroves to inland floodplains, wet grasslands, fens and peatbogs. Fishponds, rice paddies and saltpans are human-made wetlands.
Why are they important?
Although they only cover six percent of the worlds surface, wetlands provide a huge array of beneficial services, making them the most valuable ecosystems in the world – yes, even more valuable than tropical rainforests! In the UK, the services provided by wetlands save the UK economy £6.7 billion per year.
So, what are these important services that wetlands provide? Technically known as ‘ecosystem services’ these include food and raw materials, cultural services including recreation, and supporting services such as soil formation. But what wetlands are even more valuable for are their 'regulating services' which mitigate climate change and extreme climate events, including flooding, erosion control and carbon sequestration.
But, despite the vital services wetlands provide, they are unfortunately some of the most degraded habitats in the world, due partly to our belated understanding of their importance to the wider environment and society. Freshwater wetlands are the most degraded ecosystems on Earth, and we have lost 50% globally since the 1900s. Fragmentation, modification and development are the main factors involved in their loss.
Wetlands in the High Weald
At first glance, the High Weald may not seem to be a very ‘wet’ landscape, but in fact this historic region is home to many different wetland environments. From the headwaters of seven river catchments which disperse across East Sussex, West Sussex and Kent and their associated rivers and tributaries, riparian (river) habitats as well as floodplains, reed beds, springs, carr woodlands and coastal grazing marsh.
One of the particularly special characteristics of the High Weald landscape is the gill stream (above). Gill woodlands are formed in narrow and steeply sided valleys as a result of water erosion. Gill streams - as well as other water sources - are related to the early development of settlements across the High Weald. Often highly species-rich particularly with mosses, ferns, algae and lichens because of the high humidity and stable microclimate, ghylls are unique to the South East of England and internationally scarce. However, they cover 191 km2 in the High Weald. Gill streams are the waterways that run through these steep sided valleys, proviiding habitat for::
- round-leaved crowsfoot, a relation of buttercups,
- large bitter-cress which is a characteristic plant of the sides of ghyll streams, and;
- spiked rampion, an endangered plant limited mainly to the High Weald that also grows at the side of ghyll streams.
Threats to Ghyll streams include water abstraction (removing water from the gill, e.g. for irrigation or flood control purposes) and impoundment (e.g. creating dams) which can impact the microclimate, as can increased shade or increased light.
The High Weald landscape contains five times the number of ponds per square kilometre than the national average, with more than 13,000 ponds mapped across the AONB. The high number of ponds across this landscape is in part a result of how the High Weald area has been managed for hundreds of years.
Small streams were often dammed to create pools and ponds, known as hammer and mill ponds, which provided energy for the area’s iron works industry and water mills. The excavation of sandstone has also left behind many pits and small quarries now filled with water, providing further wet habitats across the High Weald.
Due to each pond’s individual characteristics ponds often support a greater diversity of species than other inland wetlands. Ponds provide habitats for many species, including high priority and protected species such great crested newts, water voles, shining ramshorn snail and medicinal leech. Threats to our ponds come from a range of factors comprising the introduction of foreign and invasive species, over-management such as over deepening, pollution including run-off and loss of surrounding habitats.
Water and wetlands have helped shape the High Weald landscape and were incredibly important to both settlement and industry over many centuries. They support rare habitats and species found almost nowhere else, as well as still providing critical services such as water storage on floodplains. By understanding these important and precious ecosystems, everyone can lend their support to their recovery and restoration, and use that knowledge to spread awareness.