Coastal & Floodplain Grazing Marsh

Coastal & Floodplain Grazing Marsh - John Miller - Explore Kent

Current Status

Coastal and floodplain grazing marshes are periodically inundated pasture or meadow with ditches, which maintain the water levels, and contain standing brackish or fresh water. Most are grazed; some are cut for hay or silage. They contain seasonal or permanent water filled hollows or ponds and emergent swamp communities but not extensive areas of tall fen. They often occur as part of a wider wetland matrix which includes open water, reed bed, and maybe wet woodland. Grazing marsh is important for waders and wintering wildfowl, in some cases supporting such large populations that they are internationally important. Grazing marsh may contain both species poor improved grassland and floristically rich semi-improved grassland, depending on how the land is managed. The ditches may have a range of salinities and thus support a diverse & interesting mixture of plants and invertebrates including many nationally scarce and threatened species. Kent's coastal grazing marsh is the remaining stronghold in Kent for the declining water vole and is important for the long-term survival of a number of priority invertebrate species including, Fisher’s estuarine moth, marshmallow moth, shrill carder bee and others.

The Kent Habitat Survey of 2003 identifies around 6900 ha of grazing marsh; this figure is lower than previous estimates due to differences in the way grazing marsh was recorded in earlier habitat surveys and is an estimate as grazing marsh is not recorded as a habitat type in the survey. Kent holds a small proportion of the total UK grazing marsh but almost 25% of the national total of semi-natural grazing marsh.

Grazing marsh in Kent is found along the Greater Thames Estuary, in the Swale Estuary, at Dartford Marshes and on Walland and Romney Marshes, with small areas at Sandwich bay, Stodmarsh and north of Dymchurch.

Factors

• Direct loss of habitat due to development and industrialisation, particularly in the Greater Thames Estuary. • Direct loss of habitat due to coastal erosion and sea level rise. • Risk of habitat loss if managed realignment of flood defences is carried out. • Addition of fertilizers to improve grassland lead to loss of species diversity. • Water level management and availability of water: drying out of grazing marsh through potential impacts of drainage schemes and ground water abstraction, poor maintenance of ditches. • Cessation of management (usually grazing) and/or removal from the agricultural system. • Overgrazing. • Change of agricultural use, particularly by conversion to arable. • Inappropriate management: the timing of grazing or mowing regimes to coincide with breeding or flowering times of important species. • Risk of water pollution by herbicide, pesticide and fertilizer, and run-off from roads and development, including sustainable urban drainage systems. • Disturbance from recreational use. • Indirect impacts include the impact of development on hydrology, the viability of remaining farmland, increased recreational pressure due to nearby development.

Current Action

• 88% of grazing marsh in Kent is designated as SSSI with a substantial proportion of this also designated as SPA/Ramsar sites. A further 7% is designated as SNCI. • There are significant areas of grazing marsh in nature reserves at Cliffe Pools, Shorne Marshes, Northward Hill, Oare Marshes, Swale NNR and Elmley. National Nature Reserves and other reserves currently hold around 1600ha of grazing marsh. • Water level management plans have been produced by the Environment Agency and Internal Drainage Boards for some areas of grazing marsh. • The Thames Estuary 2100 plan addresses issues relating to sea-level rise and the need to replace grazing marsh which might be lost to managed realignment; this links closely to the Environment Agency’s Regional Habitat Creation Programme. • Groundwork Kent and Medway are leading on a project to restore, manage and interpret grazing marsh at Dartford Marshes.

Objectives

  1. To maintain the extent and quality of existing areas of semi-natural grazing marsh.

  2. To bring all existing areas of semi-natural grazing marsh into appropriate management.

  3. To create new habitat from arable land, especially where it will link existing areas of grazing marsh.

Relevant Habitat Action Plans

The relevant UK Habitat Action Plans:

The relevant UK Species Action Plans:

The relevant Kent Habitat Action Plans:

  • Coastal saltmarsh
  • Lowland fen
  • Reedbeds
  • Standing open water