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1 Simulation models of forest stand dynamics have increased understanding of over-storey vegetation functioning, and have facilitated the development of tools capable of assessing possible successional trajectories. However, few models incorporate the response of the field layer vegetation despite it being another key component of forest ecosystems. 2 Our main objective was to assess the degree to which field-layer vegetation composition in forests is determined by variables operating at different scales, from regional (e.g. climate, location) to local factors (e.g. basal area of canopy trees, management). 3 We used data gathered during a nationwide forest survey to assess the relative effects of a broad spectrum of environmental variables on species composition. Variation partitioning was used to examine the relative contribution of subsets of environmental variables such as site spatial variation, boundary type and presence of herbivores. 4 Ordination confirmed hypotheses that field layer vegetation is primarily structured by two composite geo-climatic gradients. However, variation partitioning demonstrated that site- and plot-scale management factors also strongly influence the floristic composition of forest patches. 5 Disturbance variables (site boundary type/regional presence of deer) accounted for considerable species variation, exceeding that due to either site spatial variation or forest structure. 6 This is the first time variation attributable to such a comprehensive range of environmental variables has been quantified for forests surveyed at a national scale. We thus provide a context within which regional studies, or analyses considering a more limited range of factors, can be viewed, and a framework from which robust models of floristic response to gradual and episodic natural and anthropogenic disturbances may be developed. 7 The methodology we present, including a novel technique for the identification and removal of outliers in large data sets, provides a unique and standardized means of assessing the relative importance of diverse environmental drivers across a range of habitat types at the landscape scale, and is readily applicable elsewhere. [ABSTRACT FROM AUTHOR]

Aim To produce a statistical stratification of the European environment, suitable for stratified random sampling of ecological resources, the selection of sites for representative studies across the continent, and to provide strata for modelling exercises and reporting. Location A ‘Greater European Window’ with the following boundaries: 11° W, 32° E, 34° N, 72° N. Methods Twenty of the most relevant available environmental variables were selected, based on experience from previous studies. Principal components analysis (PCA) was used to explain 88% of the variation into three dimensions, which were subsequently clustered using an ISODATA clustering routine. The mean first principal component values of the classification variables were used to aggregate the strata into Environmental Zones and to provide a basis for consistent nomenclature. Results The Environmental Stratification of Europe (EnS) consists of 84 strata, which have been aggregated into 13 Environmental Zones. The stratification has a 1 km2 resolution. Aggregations of the strata have been compared to other European classifications using the Kappa statistic, and show ‘good’ comparisons. The individual strata have been described using data from available environmental databases. The EnS is available for noncommercial use by applying to the corresponding author. Main conclusions The Environmental Stratification of Europe has been constructed using tried and tested statistical procedures. It forms an appropriate stratification for stratified random sampling of ecological resources, the selection of sites for representative studies across the continent and for the provision of strata for modelling exercises and reporting at the European scale. [ABSTRACT FROM AUTHOR]

Abstract Aim This study aims to assess the sensitivity of calcareous grassland vegetation to climate change and to indicate the most probable direction of change. Location The study area was a region of Britain, Ireland, France and Spain, centred on the Bay of Biscay, which was defined using a land classification based on climatic criteria. Methods Vegetation was sampled in the field, with additional data collected on soils, climate, management and land cover. The vegetation samples were ordinated by detrended correspondence analysis in order to explore the main gradients present and as a basis for modelling changes. Environmental data were summarized by ordination techniques, with the scores generated used to predict the current vegetation score on the first two ordination axes by multiple regression. The model was then manipulated to represent a 2 °C increase in temperature and resulting shifts in the vegetation samples in terms of their species composition assessed. Results There was a good general agreement between the original vegetation ordination axis scores and those predicted by the model, the latter of which were based on environmental data alone. Following a 2 °C increase in temperature, the predicted changes in the ordination space were demonstrated to be subtle, consisting of small shifts towards vegetation associated with warmer conditions, representing distances 100 km or less on the ground. Main conclusions The models are simple but nevertheless provide a useful basis for the investigation of potential vegetation change. The shifts in the ordination space represent more minor changes than those predicted in previous studies. This suggests that the potential for major change is lower when environmental factors such as soil and management are considered in addition to climate. The potential for change is also reduced when vegetation is considered as a whole rather than on an individual species basis, due to both interspecific interactions and interactions with environmental factors acting as constraints. [ABSTRACT FROM AUTHOR]

The article presents an ecological study of Ysgolion Duon, a mountain cliff in Snowdonia, Wales. The study aims to determine the relation of species distributions on a mountain cliff with environmental factors. Differences in climate between the cliff and surrounding grasslands were studied. Results showed that orloci ordination procedure was able to establish the correlation of species distributions with an environmental gradient from wet eutrophic to dry oligotrophic. The presence of relict species in the flora and the isolation of the cliff from many biotic influences suggests that the vegetation is continuous.

Tree and shrub litter-fall was collected at fortnightly intervals over a three-year period on a reference hectare in a mixed deciduous woodland growing on a calcareous site in northern England. The annual total of all litter types varied from 499 g/m² to 525 g/m² in the three years. Non-woody litter varied from 363 g/m² to 393 g/m² and showed low variability both between collection sites and between years whilst woody litter varied from 106 g/m² to 162 g/m² and showed high variability. Seasonal pattern in litter-fall was very marked, up to 81 % of the annual total falling in the period September to November. The difference in leaf-fall periodicity between hazel and the overstorey was clearly demonstrated during each of the three years considered. [ABSTRACT FROM AUTHOR]

We report the impact of an extreme weather event, the October 1987 severe storm, on fragmented woodlands in southern Britain. We analysed ecological changes between 1971 and 2002 in 143 200-m2 plots in 10 woodland sites exposed to the storm with an ecologically equivalent sample of 150 plots in 16 non-exposed sites. Comparing both years, understorey plant species-richness, species composition, soil pH and woody basal area of the tree and shrub canopy were measured. We tested the hypothesis that the storm had deflected sites from the wider national trajectory of an increase in woody basal area and reduced understorey species-richness associated with ageing canopies and declining woodland management. We also expected storm disturbance to amplify the background trend of increasing soil pH, a UK-wide response to reduced atmospheric sulphur deposition. Path analysis was used to quantify indirect effects of storm exposure on understorey species richness via changes in woody basal area and soil pH. By 2002, storm exposure was estimated to have increased mean species richness per 200 m2 by 32%. Woody basal area changes were highly variable and did not significantly differ with storm exposure. Increasing soil pH was associated with a 7% increase in richness. There was no evidence that soil pH increased more as a function of storm exposure. Changes in species richness and basal area were negatively correlated: a 3.4% decrease in richness occurred for every 0.1-m2 increase in woody basal area per plot. Despite all sites substantially exceeding the empirical critical load for nitrogen deposition, there was no evidence that in the 15 years since the storm, disturbance had triggered a eutrophication effect associated with dominance of gaps by nitrophilous species. Synthesis. Although the impacts of the 1987 storm were spatially variable in terms of impacts on woody basal area, the storm had a positive effect on understorey species richness. There was no evidence that disturbance had increased dominance of gaps by invasive species. This could change if recovery from acidification results in a soil pH regime associated with greater macronutrient availability.", Organismic and Evolutionary Biology

Summary 1. Recent changes in population size of butterflies and farmland birds across north-west European landscapes have been linked to the effects of agricultural intensification. Reduction in food supply has been postulated as one of the proximal causes of these trends but the generality of this explanation has not been tested at a large scale and across animal species. 2. Changes in abundance of food plants for butterfly larvae and lowland farmland birds in the British countryside were analysed for the period 1978–90 using data from fixed plots recorded as part of the countryside surveys of Britain. 3. Associations were sought between these changes and trends in population size of selected butterflies and birds recorded from long-term monitoring schemes. 4. No associations were found between change in abundance of food plants and either increasing, stable or decreasing animal groups. At the level of individual animal species, significantly more decreases than increases in food plant frequency were found for herbivorous bird species irrespective of population trend. The size of the reduction in food plant frequency was also significantly greater for the declining bird group than for stable or increasing groups. 5. Few significant associations were detected between population trend and food plant trend for butterfly species. However, the results suggested a positive relationship between increasing butterflies and increased abundance of Elytrigia repens and Urtica dioica. 6. Food plants that increased in abundance comprised species favoured by lack of management and increased nutrient availability. Increases in abundance were also associated with linear landscape features such as hedges and streamsides. Decreasing plant species included arable weeds and stress-tolerant species typical of unimproved grasslands. 7. Based on evidence of local associations between animal and food plant change and the need for viable populations of food plants to exist within the range of each animal species, we support measures designed to enhance and maintain populations of declining food plants. Much evidence now exists to identify practical measures that husband food resources for many bird and butterfly species. The challenge for conservation policy is to manage their implementation at scales necessary to influence national trends. [ABSTRACT FROM AUTHOR]

The relationship between vegetation and environment was investigatedfor calcareous grasslands in a region in the west of Spain, France, Britain and Ireland defined by climatic criteria. Vegetation was sampled using objective methods and data collected on soils, land cover, location and management. Climate data were obtained from an availabledatabase. Examination of the first axis of vegetation variation as defined by Detrended Correspondence Analysis (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 between the vegetation gradients and environmental variables were determined. The strongest correlations with the first DCA axis were for temperature, latitude, soil organic matter, grazing and land cover. The second DCA axis was 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 relating to land cover and management should also be taken into account. [ABSTRACT FROM AUTHOR]