The Ecology of Morecambe Bay. VII. The Distribution of Puccinellia maritima, Festuca rubra and Agrostis stolonifera in the Salt Marshes

Abstract

The distribution of P. maritima, F. rubra and A. stolonifera was investigated in the salt marshes of Morecambe Bay. Puccinellia was largely restricted to immature soils at low elevations and more organic soils with high Na contents; Festuca and Agrostis both occurred at higher elevations in more organic and less saline soils. The 3 spp. occurred together in the high level saltings, where Puccinellia occurred in the hollows, Festuca on the humps, and Agrostis on the edges of humps. The 3 spp. were grown together in pairs in replacement series (de Wit 1960) with various water levels, soil types and salinities. Puccinellia was more competitive than the other grasses when seawater was applied, and Agrostis was usually the most competitive species in fresh water conditions. Puccinellia had a competitive advantage over Festuca at high water tables. The large and small scale distribution patterns of the 3 spp. on the salt marshes are determined by their competitive abilities under various waterlogging and salinity conditions. Sheep grazing and turf cutting reduce the Festuca content of the sward, and are important management methods in maintaining this type of salt marsh.