Changing status of Blysmus compressus (Flat Sedge) in the Sefton Coast sand-dunes, north Merseyside, UK

Abstract

A 2018 survey of the nationally ‘Vulnerable’ Blysmus compressus (Flat-sedge) in the Sefton Coast sand-dunes, north Merseyside (v.c.59, South Lancashire), aimed to update information collected on distribution and habitats a decade earlier. As in 2008, the plant was mainly found in calcareous dune-slacks of recent origin, with short, open, species-rich vegetation on gley soils with a relatively high pH. Sites with a lower sward height supported a higher percentage cover of B. compressus. The largest populations were associated with sites that had been disturbed by recreational trampling, occasional vehicle use and/or grazing, especially by rabbits. Twenty-two sites were recorded, seven being new. Overall, the area occupied by B. compressus declined by 17%, two 2008 sites being lost. Similarly, an estimate of 15-20,000 plants in the earlier survey fell to 12,600. Losses were attributed to vegetation overgrowth and scrub development, partly resulting from lower rabbit numbers and reduced management input. The plant occurred in a range of vegetation types but matches to known UK National Vegetation Classification communities were generally poor. Management methods to conserve B. compressus and other vulnerable taxa are discussed.