Communities containing Juncus squarrosus in upper Teesdale, England

Abstract

Plant communities containing Juncus squarrosus were analysed in a 100 km2 area at the head of Teesdale in the north Pennines. The method of successive approximation was applied, using quadrats of 1/4m2. Five noda were recognised, and their relation to noda previously described from the Scottish Highlands is discussed. The species-rich Juncus-Nardus nodum on irrigated gley soils, and the Juncus-Festuca rubra-Mnium punctatum nodum on flushed peat, contain many hydrophilic species and together constitute an association called species-rich Juncetum squarrosi sub-alpinum. The species-poor Juncus-Nardus nodum occurs on gley soils poorer in bases, and is probably a facies of species-poor Nardetum sub-alpinum. The remaining two noda, the Juncus-Vaccinium myrtillus and the Juncus-Carex nigra-Polytrichum commune, are found on acid, humus-rich soils, being differentiated by freedom of drainage. They contain little Nardus, but constitute an association called species-poor Juncetum squarrosi sub-alpinum. This occupies a considerable area in upper Teesdale, but differs from similar communities described in the Carneddau of north Wales and in the Scottish Highlands in that Agrostis spp. and Anthoxanthum odoratum are scarce. This is perhaps due to long-continued grazing by sheep.