Grouville Marsh, also known as Les Maltières, is a 89.5 vergée wetland comprising reed beds, wet woodland, fen, and grazed wet meadows. It is Jersey’s second most important wetland site and is rich in bird and insect life, so much so that it was designated a Site of Special Scientific Interest in 2009. Over the years 165 species of birds have been recorded ranging from fairly common breeding birds like Eurasian Reed Warbler and Black caps to rare winter visitors like the Eurasian bittern and Black-crowned Night Heron. Today it is also home to Marsh harriers, who regularly nest amongst the stands of willow.
The site is largely owned by the Chef Tenants du Fief de la Reine Grouville, with the National Trust currently caring for 12 vergées. Together with the Chef Tenants, the Trust now manages the land as a nature reserve, with a regular programme of reed bed and willow management to safeguard and enhance biodiversity. However, in times past the site was not so fortunate, having been used as a prisoner of war camp and for peat extraction during the Second World War, before becoming a parish dump and partially being drained for development or agriculture.
The Trust’s land is mainly made up of reed bed and willow carr which provides a whole range of opportunities for many birds plants and specialist invertebrates like the 29 species of hoverfly alone, recorded in this relatively small site.
To keep this habitat in good condition, our Lands Team annually cut and clear sections of reed bed to vary the height and age structure of the reeds, and reduce the amount of leaf litter build up. This, provides an opportunity for a wider diversity of fen plants like Pendulous sedge and Water Purslane as well as preventing the area from “drying out”. Large numbers of invertebrates, including small aphids, are found on the stems and leaves of the Phragmite reeds. These prove an essential food supply for bird species such as Sedge Warblers, who need to stock up their fat reserves, on their way through from northern Europe to their wintering grounds in sub-Saharan Africa.
Similarly stands of willow trees are coppiced on a 3 year rotational basis to once again vary the height and age structure. This, allows sunlight to penetrate darkened areas enabling other plants to flourish as well as prolonging the life of the trees. If no coppicing took place the area would inevitably dry out and in the longer term revert to scrub. The arisings also provide a highly sustainable source of firewood and fencing material as a by-product.
Both of these activities are performed outside of the breeding season to avoid disturbance to the birds
In 2016/2017 the Trust is planning to re-establish a large open area of water amongst the reed bed which has been largely lost due to the build-up of silt and decaying organic material. Once achieved, the pond will attract waterfowl and waders such as Teal, Widgeon and Little Grebe and provide breeding opportunities for dragonflies, newts and toads. It will also have the added benefit of increasing the diversity of aquatic plants. The project is being generously supported by the One Foundation.
In the longer term , the Trust intends to increase the amount of surveying and monitoring of key species so as to continuously assess the condition of the habitat and inform future management decisions.
The dramatic extent of post-war development and the drainage of land for agriculture over the years has unfortunately resulted in hugely valuable wetland habitats disappear across the island and nowhere more so than the south and east coasts. The fragmentation and reduction in the size of wetlands have led to declines in once common flora and fauna, which makes Grouville Marsh one of the last bastions for some wildlife and why it is regarded by naturalists as the second most important wetland site in the island after St Ouen’s Pond.
Unfortunately development continues to take place along the fringes of the marsh due to an increased demand for housing around Gorey Village. Extensive development has taken place along Les Maltieries, with plans to redevelop de la Mare Nurseries over the next couple of years. It is feared that this could exacerbate the drying out of the marsh in the longer term as well as increase disturbance and threats from domestic animals such as cats. Pollutants and wash off can also have a devastating impact upon the ecology, although fortunately reed beds are able to filter out and neutralise harmful bacteria and chemicals, making them an incredibly value tool for managing the health of our water systems.
In the future the Trust hopes to be able to acquire further land around the marsh in order to create a valuable buffer zone to secure the permanent protection of this unique and highly important ecological site.