Aspects of the population biology ofLiparis loeselii(L.) Rich. var.ovataRidd. ex Godfery (Orchidaceae) in the dune slacks of South Wales, UK

Abstract

Demographic techniques have been employed to study populations of the rare orchidLiparis loeseliivar.ovataacross a range of dune slack habitats at a South Wales site. The study has shown that very large numbers of shoots (>300) may occur within a single 1×1 m quadrat and that the vegetative production of side shoots is common. Regular population surveys over time have shown that individuals represented by a single shoot can live for 8 years. Subsequent analyses of the floristic composition of the study quadrats has revealed the presence of subtle variations in species composition and vegetation structure in relation to age and hydrology, although all of the plots still fall within the SD14Salix repens-Campylium stellatumdune slack community defined by the British National Vegetation Classification. When attributes of population flux are analysed in relation to floristic composition, one significant trend to emerge is that the appearance of new genets is most prevalent in successionally young slacks. As the natural formation of new slacks by sand blow is now a rare event in the South Wales dune field, the management ofLiparis loeseliivar.ovatais currently aimed at attempting to ensure the persistence of suitable communities through biomass reduction techniques.