Vegetation gradients in Atlantic Europe: the use of existing phytosociological data in preliminary investigations on the potential effects of climate change on British vegetation

Abstract

1 This paper aims to demonstrate the use of available vegetation data from the phytosociological literature in preliminary analyses to generate hypotheses regarding vegetation and climate change. 2 Data for over 3000 samples of calcareous grassland, mesotrophic grassland, heath and woodland vegetation were taken from the literature for a region in the west of Atlantic Europe and subjected to ordination by detrended correspondence analysis in order to identify the main gradients present. 3 Climate data were obtained at a resolution of 0.5° from an existing database. The relationship between vegetation composition and climate was investigated by the correlation of the mean scores for the first two ordination axes for each 0.5° cell with the climate and location variables. 4 The ordinations resulted in clear geographical gradients for calcareous grasslands, heaths and woodlands but not for mesotrophic grasslands. Significant correlations were shown between some of the vegetation gradients and the climate variables, with the strongest relationships occurring between the calcareous grassland gradients and July temperature, latitude and oceanicity. Some of the vegetation gradients were also inferred to reflect edaphic factors, management and vegetation history. 5 Those gradients that were related to temperature were hypothesized to reflect the influence of a progressively warmer climate on species composition, providing a baseline for further studies on the influence of climate change on species composition. 6 The validity of the literature data was assessed by the collection of an original set of field data for calcareous grasslands and the subsequent ordination of a dataset containing samples from both the literature and the field. The considerable overlap between the samples from the literature and the field suggest that literature data can be used, despite certain limitations. Such preliminary analyses, using readily available data, can thus achieve useful results, thereby saving lengthy and costly field visits.