Vegetation-environment relationships in Atlantic European calcareous grasslands

The relationship between vegetation and environment was investigated for ca lcareous grasslands in a region in the west of Spain, France, Britain and I reland defined by climatic criteria. Vegetation was sampled using objective methods and data collected an soils, land cover, location and management. Climate data were obtained from an available database. Examination of the f irst axis of vegetation variation as defined by Detrended Correspondence An alysis (DCA) showed a gradient from the Irish and British samples to those from France. The Spanish samples formed a separate group on the second axis . The species composition along the gradients is discussed. Correlations be tween the vegetation gradients and environmental variables were determined. The strongest correlations with the first DCA axis were for temperature, l atitude, soil organic matter, grazing and land cover. The second DCA axis w as highly correlated with rainfall, altitude and land cover. The third and fourth DCA axes were more difficult to interpret but appeared to be related to land cover. The results indicate that climate factors are important at this scale, but should not be considered in isolation and that factors rela ting to land cover and management should also be taken into account.