The ecology of Morecambe Bay. 7. The distribution of Puccinellia maritima, Festuca rubra and Agrostis stolonifera in the salt marshes.
Abstract
In the salt marshes of Morecambe Bay P. maritima was largely restricted to immature soils at low elevations and more organic soils with high Na contents; F. rubra and A. stolonifera both occurred at higher elevations in more organic and less saline soils. The 3 species occurred together in the high level saltings, where P. maritima occurred in the hollows, F. rubra on the humps, and A. stolonifera on the edges of humps. In pot trials, the 3 species were grown together in pairs in replacement series [see HbA 32, 1572] with various water levels, soil types and salinities. P. maritima was more competitive than the other grasses when seawater was applied, and A. stolonifera was usually the most competitive species in fresh water conditions. P. maritima had a competitive advantage over F. rubra at high water tables. The results of the experiments suggested that the large and small scale distribution patterns of the 3 species on the salt marshes were determined by their competitive abilities under various waterlogging and salinity conditions. Sheep grazing and turf cutting reduced the F. rubra content of the sward, and were important management methods in maintaining this type of salt marsh.