An investigation into changes in composition and distribution of the vegetation of Widdybank Fell, upper Teesdale, during the last twenty years

Abstract

A survey of some areas of the Widdybank Fell area of Upper Teesdale was carried out over a single summer to attempt to detect any changes which may have occurred in the distribution and composition of communities in the twenty-five years since an original survey was carried out during the construction of the adjacent Cow Green Reservoir (Jones 1973).A vegetative survey concentrated on the species composition of six of the 30+ communities originally defined (Jones, 1973) and the results were compared with those of the original survey using multivariate analysis techniques. Several areas of the fell were also mapped in terms of the vegetative community distribution. This mapping utilised both computer enhanced aerial photographic images and ground surveys and validification. The results of this mapping are compared with the community distributions produced from the original survey (Bradshaw and Jones, 1976). Further studies were also carried on the effects of different grazing regimes on the limestone grassland. An analysis of the original data set was carried out using a multivariate technique and the resultant classification compared to the Zurich-Montpellier method used in the original analysis. The communities are also classified in terms of the NVC vegetation communities and their fit into this system of classification is discussed. The changes detected are discussed in relation to several environmental factors operating on the fell which were considered as possible causes of the changes.. Such factors include grazing pressure, changing atmospheric deposition and pollution, global warming and associated atmospheric changes, anthropogenic effects, effects of the Cow Green Reservoir and the various management activities carried out on the habitats present.