Species Poor Wet Grasslands
Some species poor grasslands are also important for wildlife. Purple moor-grass and rush pasture (MG10, Rodwell, 1992) occurs in lowland areas on poorly drained, acidic soils (Natural England, 2010b). The habitat commonly establishes within a mosaic of other habitats including heathlands, grasslands with wet flushes, and marginal areas of fens where fertility levels are low. It is often dominated by a high number of sedges, tussock grasses, rushes and flowering plants, making it valuable for insects and ground nesting birds.
A high diversity of species is not always an indicator of either naturalness or of good quality wildlife habitat. Unimproved species-poor wet meadows are one example of this. These meadows are low diversity sites of high ecological value, supporting unique assemblages of plants, birds and insects, which are not found in more species-rich sites. They can be particularly important for breeding and wintering wading birds.
Similar to species-rich meadows, there is little data available on the distribution of rush pasture or species-poor unimproved grasslands in Sussex, and no accurate judgement can be made on their overall status in the County. Only 175 ha of rush pasture and purple-moor grass habitats are currently mapped in the Sussex Habitat Framework, although there is significantly more known to be present. It is likely however that ‘good quality’ species poor grasslands and rush pasture are a relatively rare feature of lowland Sussex and that they are highly fragmented compared to historic distributions.
The area of these habitats in Sussex are likely to be low overall, but they may nonetheless be both locally and nationally significant, particularly as Rush pasture is a niche habitat of Southern lowland Britain. Many of our species poor wet grasslands also occur in our acid heathland areas. The grip draining of many of our heathland habitats along with the widespread use of agricultural fertilisers and drilling to agriculturally ‘improve’ lowland grasslands is likely to have played a significant part in the decline of species-poor unimproved grasslands across Sussex.