Indicator Values For Temperature Research Articles

Thermophilisation of communities differs between land plant lineages, land use types and elevation

Bryophytes provide key ecosystem services at the global scale such as carbon storage and primary production in resource limited habitats, but compared to vascular plants knowledge on how these organisms face recent climate warming is fragmentary. This is particularly critical because bryophytes differ fundamentally from vascular plants in their ecophysiological and biological characteristics, so that community alterations most likely have different dynamics. In a comparative approach, we analysed thermophilisation of bryophyte and vascular plant communities in 1146 permanent plots distributed along an elevational gradient of nearly 3.000 m in Switzerland (Central Europe) that were visited in 5-years intervals between 2001 and 2021. We estimated thermophilisation from changes in unweighted mean temperature indicator values of species, compared it to expected thermophilisation rates given the shift of isotherms and addressed differences between the two lineages, major land use types (managed grasslands, forests, unmanaged open areas), life strategy types (long- and short-lived species) and in elevation. Thermophilisation of bryophyte communities was on average 2.1 times higher than of vascular plant communities and at high elevations it approximated the expected rate given the shift of isotherms. Thermophilisation of both, bryophyte and vascular plant communities was not driven by a loss of cryophilic species but by an increase in thermophilic and mesophilic species, indicating an in-filling process. Furthermore, our data show that thermophilisation is higher in managed grasslands than in forests. We suggest that the higher responsiveness of bryophytes compared to vascular plants depends on their poikilohydry and dispersal capacity and that lower thermophilisation of forests communities is related to the buffering effect of microclimatic conditions in the interior of forests. Our study emphasises the heterogeneity of climate warming effects on plants because response dynamics differ between taxonomic groups as well as between land use types and along elevational gradients.

Calibrating ecological indicator values and niche width for a Mediterranean flora

Bioindication of ecological variables such as humidity, temperature or pH by ecological indicator values of plants is a powerful tool for research in plant ecology, e.g. to detect early vegetation changes. Here, we provide a data set of ecological indicator values including niche width for an entire regional flora. We used an extensive data-base with floristic relevés from Southern France to recalibrate indicator values for light (L), temperature (T), continentality (K), air humidity (A), soil moisture (F), pH (R), productivity (N), soil texture (G), soil organic matter content (O) and salinity (S). Values were recalibrated using average values from co-occurring plants, enabling to develop indicator values for species not yet evaluated previously. Recalibrated values are on a continuous scale and we add standard deviation, median, first and third quartile for each indicator value. Linear regression of average indicator values against measured factors showed higher correlation with recalibrated values compared to original indicator values for temperature, pH and nitrogen, and comparable R2 for moisture. Individual indicator systems performed better than a combination and applying different weighting procedures demonstrated the usefulness of inverse variance. We further illustrate graphically how recalibrated values and niche width increase ecological knowledge on plants.

A Novel Unified Environmental Quality Control Index based on AI Towards Smart building Optimization

Assessment and monitoring of health and working conditions in the workplace is an important issue. Human health, safety and productivity are not only greatly affected by health and working conditions, but the equipment, machinery and materials in those environments can be affected in ways that lead to degradation. This paper presents a way to use artificial intelligence in developing a novel entity index for assessing and monitoring workplace health and conditions of use in intelligent buildings. Based on fuzzy logic, two algorithms were developed to determine the relationships and dependencies between various immediate environmental indicators and underlying environmental variables, to account for these relationships and trends, and finally to represent the indicator values for temperature, health and working conditions. A table was developed with temperature ranges and the effects on occupancy experience within those ranges. The current environmental indicators used in the previously unambiguous algorithm to generate new index values are apparent temperature (air cooling coefficient, wet bulb temperature and heat index), temperature and humidity index, discomfort index, warmth, comfort, and heat capacity. Based on Fuzzy logic, the environment variables of the algorithm are ambient temperature, relative humidity, and air velocity. After developing a complete system model using MATLAB/Simulink, further testing and evaluating the algorithm design, a model was created containing all indexed sub models, fuzzy sub model algorithms, input blocks, and data visualizations.

Evaluating the ecological realism of plant species distribution models with ecological indicator values

Species distribution models (SDMs) are routinely applied to assess current as well as future species distributions, for example to assess impacts of future environmental change on biodiversity or to underpin conservation planning. It has been repeatedly emphasized that SDMs should be evaluated based not only on their goodness of fit to the data, but also on the realism of the modeled ecological responses. However, possibilities for the latter are hampered by limited knowledge on the true responses as well as a lack of quantitative evaluation methods. Here we compared modeled niche optima obtained from European‐scale SDMs of 1476 terrestrial vascular plant species with empirical ecological indicator values indicating the preferences of plant species for key environmental conditions. For each plant species we first fitted an ensemble SDM including three modeling techniques (GLM, GAM and BRT) and extracted niche optima for climate, soil, land use and nitrogen deposition variables with a large explanatory power for the occurrence of that species. We then compared these SDM‐derived niche optima with the ecological indicator values by means of bivariate correlation analysis. We found weak to moderate correlations in the expected direction between the SDM‐derived niche optima and ecological indicator values. The strongest correlation occurred between the modeled optima for growing degree days and the ecological indicator values for temperature. Correlations were weaker for SDM‐derived niche optima with a more distal relationship to ecological indicator values (notably precipitation and soil moisture). Further, correlations were consistently highest for BRT, followed by GLM and GAM. Our method gives insight into the ecological realism of modeled niche optima and projected core habitats and can be used to improve SDMs by making a more informed selection of environmental variables and modeling techniques.

Species turnover reveals hidden effects of decreasing nitrogen deposition in mountain hay meadows.

Nitrogen (N) deposition is a major threat to biodiversity in many habitats. The recent introduction of cleaner technologies in Switzerland has led to a reduction in the emissions of nitrogen oxides, with a consequent decrease in N deposition. We examined different drivers of plant community change, that is, N deposition, climate warming, and land-use change, in Swiss mountain hay meadows, using data from the Swiss biodiversity monitoring program. We compared indicator values of species that disappeared from or colonized a site (species turnover) with the indicator values of randomly chosen species from the same site. While oligotrophic plant species were more likely to colonize, compared to random expectation, we found only weak shifts in plant community composition. In particular, the average nutrient value of plant communities remained stable over time (2003–2017). We found the largest deviations from random expectation in the nutrient values of colonizing species, suggesting that N deposition or other factors that change the nutrient content of soils were important drivers of the species composition change over the last 15 years in Swiss mountain hay meadows. In addition, we observed an overall replacement of species with lower indicator values for temperature with species with higher values. Apparently, the community effects of the replacement of eutrophic species with oligotrophic species was outweighed by climate warming. Our results add to the increasing evidence that plant communities in changing environments may be relatively stable regarding average species richness or average indicator values, but that this apparent stability is often accompanied by a marked turnover of species.

Recent changes in alpine vegetation differ among plant communities

AbstractAimReports on recent changes in high‐mountain vegetation are mostly based on re‐surveys of mountaintop floras. Summits are very specific habitats, however, and detected trends may not necessarily represent alpine vegetation in general. Here, we analyse re‐samples of three prevalent plant communities in non‐summit alpine habitats (snowbeds, two grassland types).LocationNortheastern European Alps.MethodsIn 2013 we re‐sampled a total of 91 relevés of three plant communities from the 1990s. We compared original and re‐samples in terms of species richness (α‐diversity), pair‐wise compositional dissimilarity (β‐diversity) and species pool size (γ‐diversity). Moreover, we calculated mean ecological indicator values (temperature, moisture, nutrient status and soil acidity) as well as potential plant height for each of the 182 relevés. Differences in species pool sizes between the two sampling campaigns were evaluated by randomization tests based on rarefaction curves. In all other cases, differences were compared using paired t‐tests or Kruskal–Wallis tests.ResultsOf all the community attributes analysed, changes were most consistent with respect to increasing mean species' temperature indicator values. Mean potential plant height also increased slightly in all three communities, but differences were statistically significant only in the case of Carex sempervirens grasslands. Changes in species richness varied among communities, with only the Carex firma grasslands accumulating significantly more species at both the local and regional scales. For the other two plant communities, α‐ and γ‐diversity remained constant, but β‐diversity increased. Indicator values other than temperature either did not change or changed idiosyncratically in the different communities.ConclusionsOur results indicate that some long‐term changes occurred in high mountain grassland and snowbed vegetation of the study area. Consistent changes in mean species' temperature indicator values suggest that climate warming was an important driver. However, trends in biodiversity metrics differed substantially between the studied communities. We conclude that recent increase in species numbers commonly reported from temperate and boreal mountaintops cannot readily be generalized to all temperate and boreal high‐mountain vegetation.

Tree ring ecological signal is consistent with floristic composition and plant indicator values in Mediterranean Fagus sylvatica forests

Summary We compared the multivariate patterns of tree ring chronologies with those of floristic composition (and of its associated Ellenberg indicator values – EIVs) across the whole elevation gradient of Fagus sylvatica forests in Central Italy (from 300 to 1900 m a.s.l.). Both data sets were also compared with bioclimatic parameters obtained from reconstructed, site‐representative meteorological data. Procrustes analysis showed that the patterns of tree ring chronologies and floristic assemblages were significantly correlated. The two main bio‐climatic belts obtained from tree ring analysis showed significantly different floristic composition and significantly different distribution of EIVs. Constrained ordination with meteorological data as covariates showed that in both data sets, most of the variation was explained by mean summer temperature, while precipitation parameters had only minor explanatory power. Ellenberg indicator values for temperature showed a strong correlation with mean summer temperature obtained from the meteorological data. EIVs for continentality were weakly correlated with annual temperature range. No correlation emerged between the EIVs for moisture and the precipitation parameters. Constrained ordination of the tree ring data set with the floras' mean EIVs as covariates found that the most explanatory variables were the EIVs for temperature followed by the EIVs for light. This latter finding is probably a consequence of temperature control (via summer drought) on canopy Leaf Area Index. Synthesis. Ecological classification of beech forest stands through either tree ring chronologies or floristic composition yields very similar results. Both bio‐indication methods point to the predominant role of growing‐season temperatures in controlling patterns and processes of forest ecosystems across wide elevation gradients. Thus, similarities in tree ring chronologies of the past between sites could be used to infer analogies in past floristic assemblages. Moreover, temperature indicator values obtained from floras show excellent accordance with meteorological data, allowing reliable usage of diachronic floristic data for climate change monitoring at detailed spatial scale.

Using ecological and life-history characteristics for projecting species' responses to climate change

Assessing the impact of climate change on range dynamics is difficult in the absence of large-extent distribution data. We developed a novel two-step approach as an instrument for biodiversity risk assessment. First, we established relationships between modelled loss of occupied grid cells (‘range loss’, R2=0.29), or gain of currently unoccupied grid cells (‘range gain’, R2=0.30), for 195 plant species with distributional data under the A1FI climate change scenario up to 2080, and ecological and life history traits (life form, leaf persistence, ecological strategy, pollen vector, Ellenberg indicator values and characteristics derived from species’ ranges). Secondly, we used the resulting coefficients to predict climatic sensitivity for 688 plant species without spatially explicit distributional information. The models predicted range losses of 34±20 % (mean±standard deviation) and range gains of 3±4 %. Specifically, measures of species’ distribution, such as range size, were significantly related to both range loss and range gain. Other traits associated with range loss (e.g. life form, number of floristic zones) were not necessarily related to range gain (instead related to Ellenberg temperature indicator), indicating that two distinct sets of ecological processes govern range expansion and contraction. We found interaction effects between moisture indicator values and life form for range loss, and between moisture and temperature indicator values for range gain. The responses of species to climate change are complex and context dependent. Thus, our results highlight the importance of incorporating trait interactions in models to assess risks of climate change. &nbsp

Using ecological and life-history characteristics for projecting species' responses to climate change

Assessing the impact of climate change on range dynamics is difficult in the absence of large-extent distribution data. We developed a novel two-step approach as an instrument for biodiversity risk assessment. First, we established relationships between modelled loss of occupied grid cells (‘range loss’, R2=0.29), or gain of currently unoccupied grid cells (‘range gain’, R2=0.30), for 195 plant species with distributional data under the A1FI climate change scenario up to 2080, and ecological and life history traits (life form, leaf persistence, ecological strategy, pollen vector, Ellenberg indicator values and characteristics derived from species’ ranges). Secondly, we used the resulting coefficients to predict climatic sensitivity for 688 plant species without spatially explicit distributional information. The models predicted range losses of 34±20 % (mean±standard deviation) and range gains of 3±4 %. Specifically, measures of species’ distribution, such as range size, were significantly related to both range loss and range gain. Other traits associated with range loss (e.g. life form, number of floristic zones) were not necessarily related to range gain (instead related to Ellenberg temperature indicator), indicating that two distinct sets of ecological processes govern range expansion and contraction. We found interaction effects between moisture indicator values and life form for range loss, and between moisture and temperature indicator values for range gain. The responses of species to climate change are complex and context dependent. Thus, our results highlight the importance of incorporating trait interactions in models to assess risks of climate change. &nbsp

The TRM Model of Potential Natural Vegetation in Mountain Forests

Due to advances in spatial modeling and improved availability of digital geodata, traditional mapping of potential natural vegetation (PNV) can be replaced by ecological modeling approaches. We developed a new model to map forest types representing the potential natural forest vegetation in the Bavarian Alps. The TRM model is founded on a three-dimensional system of the ecological gradients temperature (T), soil reaction (R), and soil moisture (M). Within such a “site cube” forest types are defined as homogenous site units that give rise to forest communities with comparable species composition, structure, production and protective functions. The three gradients were modeled using regression algorithms with area-wide, high resolution geodata on climate, relief and soil as predictors and average Ellenberg indicator values for temperature, acidity and moisture of vegetation plots as dependent variables summarizing plant responses to ecological gradients. The resulting predictor-response relationships allowed us to predict gradient positions of each raster cell in the region from geodata layers. The three-dimensional system of gradients was partitioned into 26 forest types, which can be mapped for the whole region. TRM-based units are supplemented by 22 forest types of special sites defined by other ecological factors such as geomorphology, for which individual GIS rules were developed. The application of our model results in an intermediate-scale map of potential natural forest vegetation, which is based on an explicit function of temperature, reaction and moisture and is therefore consistent and repeatable in contrast to traditional PNV maps.

Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across Northern Europe

Recent studies from mountainous areas of small spatial extent (<2500 km(2) ) suggest that fine-grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate-change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine-grained thermal variability across a 2500-km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT) and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within <1000-m(2) units (community-inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1-km(2) units; (2) the relationship between CiT range and topographically and geographically derived predictors at 1-km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100-km(2) units. Ellenberg temperature indicator values in combination with plant assemblages explained 46-72% of variation in LmT and 92-96% of variation in GiT during the growing season (June, July, August). Growing-season CiT range within 1-km(2) units peaked at 60-65°N and increased with terrain roughness, averaging 1.97 °C (SD = 0.84 °C) and 2.68 °C (SD = 1.26 °C) within the flattest and roughest units respectively. Complex interactions between topography-related variables and latitude explained 35% of variation in growing-season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing-season CiT within 100-km(2) units was, on average, 1.8 times greater (0.32 °C km(-1) ) than spatial turnover in growing-season GiT (0.18 °C km(-1) ). We conclude that thermal variability within 1-km(2) units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.

Spatial modelling-based approach to phytogeographical regionalization using grassland vegetation data

Abstract We presented a methodology for drawing continuous boundaries in the landscape differentiating between regions with different floristic composition. A region in Central Slovakia covering 2,445 km2 was investigated. Ecological indicator values for temperature (EIT) in 1,978 grassland polygons were analysed. Ordinary kriging was used to interpolate EIT across the study region. Lattice wombling was used to identify the most intensive gradients in EIT and to draw boundaries, while ANOVA was used for post-classification analysis. A strong pattern of spatial continuity was present in EIT assigned to species in grassland polygons allowing for drawing continuous boundaries in the landscape. The study region was divided into 15 districts using the proposed method. Post-classification analysis indicated that 17 out of 23 adjacent districts were found to differ significantly in term of mean value of source samples. The results implied the need for incorporating spatial autocorrelation in sample data into post-classification analysis; such factor is often neglected in ecological research. The presented findings suggested broader applicability of the proposed method for spatial modelling, as vegetation data is widely accessible in databases for many regions of Europe.

Modelling effective thermal climate for mountain forests in the Bavarian Alps: Which is the best model?

AbstractQuestion: Which thermal climate model performs best in predicting the combined effects of temperature and radiation on forest vegetation in the Bavarian Alps?Location: Bavarian Alps, Germany.Methods: In order to find the best model for effective thermal climate for the Bavarian Alps, we analysed models using the following predictors derived from climate data and/or a digital elevation model: (a) temperature variables only, (b) temperature plus slope aspect and inclination, and (c) temperature plus potential global solar radiation. Models were tested by linear regression against four response variables based on average Ellenberg indicator values for temperature (cover weighted/unweighted, with/without bryophytes), which were computed for 2280 georeferenced relevés from the vegetation database BERGWALD. We optimized (b) by empirically searching for thermally most favourable slope aspect and inclination.Results: Closest model fit was achieved for unweighted temperature values based on vascular plants without bryophytes. Model fit (adj. R2) increased from using temperature alone to temperature–radiation, to temperature–aspect–inclination as predictors. The best spatially explicit model for predicting temperature values (adj. R2=0.57) was based on the variable combination mean temperature in the growing season (May to September), slope aspect (optimal aspect 195°) and inclination (optimal slope 30°).Conclusion: Combining mean temperatures and relief variables in GIS allows creation of predictive maps of mountain forest response to thermal climate. Applied to climate change scenarios, our model can forecast potential vegetation distribution in the future. The superiority of simple empirical relief factors over a widely used model of potential radiation casts doubt on the meaningfulness of the latter for vegetation studies.

Topographically controlled thermal-habitat differentiation buffers alpine plant diversity against climate warming

Aim We aim to: (1) explore thermal habitat preferences in alpine plant species across mosaics of topographically controlled micro-habitats; (2) test the predictive value of so-called 'indicator values'; and (3) quantify the shift in micro-habitat conditions under the influence of climate warming. Location Alpine vegetation 2200-2800 m a.s.l., Swiss central Alps. Methods High-resolution infra-red thermometry and large numbers of small data loggers were used to assess the spatial and temporal variation of plant-surface and ground temperatures as well as snow-melt patterns for 889 plots distributed across three alpine slopes of contrasting exposure. These environmental data were then correlated with Landolt indicator values for temperature preferences of different plant species and vegetation units. By simulating a uniform 2 K warming we estimated the changes in abundance of micro-habitat temperatures within the study area. Results Within the study area we observed a substantial variation between micro-habitats in seasonal mean soil temperature (Delta T = 7.2 K), surface temperature (Delta T = 10.5 K) and season length (< 32 days). Plant species with low indicator values for temperature (plants commonly found in cool habitats) grew in significantly colder micro-habitats than plants with higher indicator values found on the same slope. A 2 K warming will lead to the loss of the coldest habitats (3% of current area), 75% of the current thermal micro-habitats will be reduced in abundance (crowding effect) and 22% will become more abundant. Main conclusions Our results demonstrate that the topographically induced mosaics of micro-climatic conditions in an alpine landscape are associated with local plant species distribution. Semi-quantitative plant species indicator values based on expert knowledge and aggregated to community means match measured thermal habitat conditions. Metre-scale thermal contrasts significantly exceed IPCC warming projections for the next 1 years. The data presented here thus indicate a great risk of overestimating alpine habitat losses in isotherm-based model scenarios. While all but the species depending on the very coldest micro-habitats will find thermally suitable 'escape' habitats within short distances, there will be enhanced competition for those cooler places on a given slope in an alpine climate that is 2 K warmer. Yet, due to their topographic variability, alpine landscapes are likely to be safer places for most species than lowland terrain in a warming world.

Identification of phytogeographical borders using grassland vegetation data

The paper proposes a methodology of phytogeographical regionalisation using grassland vegetation data. The research area is located in the West Carpathians, in volcanic field with adjacent post-tectonic basins and valleys in the Central Slovakia. The applied techniques were variogram modelling, ordinary kriging and lattice wombling. Phi coefficient was used to determine the diagnostic species of proposed phytochoria (fidelity test). The 1978 unevenly distributed grassland polygons that comprised 1071 taxa of vascular plants were the subject of the analyses. Ecological indicator values for temperature (EITs), weighted by species coverage in the Tansley scale in each grassland polygon, were used for the modelling. The gradients in the surface of the indicator value produced by ordinary kriging were analyzed. The steepest gradients indicate the most radical changes in floristic composition typical of border locations.

Spatial diversity of thermal preferences of vascular plants in Łódź

Using temperature indicator values according to Ellenberg, spatial diversity of the vascular flora was determined with regard to thermal preferences of species growing in the area of Łódź (the city with the third largest population in Poland). Study results were compared to meteorological data indicating the presence of an urban heat island (UHI). Analysis of spatial diversity of thermal preferences of the flora was conducted with regard to 292 basic study fields - squares with sides 1 km long. Indicator values of thermal preferences of the flora were determined for the flora of each basic study field - the number and percentage share of thermophilous species (T&gt;6) as well as the average of temperature indicator values. Thermal requirements of the vascular plant species occurring in basic fields within the area of compact tenement-style buildings, industrial and railway terrain are higher than in suburban area. Average temperature indicator values for the flora of basic study fields vary from 5.28 in the peripheries to 5.97 in city centre, while the number of thermophilous species - from 1 to 34, and percentage share of thermophilous species - from 0.6% to 17.5%.

Interpretation of altitudinal gradients in South Central Norway based on vascular plants as environmental indicators

Abstract The main aim of this study is to quantify environmental differences along altitudinal gradients on the basis of different sets of plant indicator systems and recorded vascular plants within 100-m altitudinal bands. Two areas are included in the study, and in total they include an altitudinal span from sea-level up to 2400 m a.s.l. The applied indicator systems are the six values defined by Ellenberg et al. [Ellenberg, H., Weber, H.E., Dull, R., Wirth, V., Werner, W., Paulissen, D., 1991. Zeigerwerte von Pflanzen in Mitteleuropa. Scripta Geobotanica 18, 1–248], eight Raunkiaer life forms, the respiration values of Dahl [Dahl, E., 1998. The phytography of Northern Europe. Cambridge University Press], and the snow indicator values of Odland and Munkejord [Odland, A., Munkejord, H.K., 2008. Plants as indicators of snow layer duration in southern Norwegian mountains. Ecological Indicators 8, 57–68]. Mean indicator values are calculated for each altitudinal band, and they show significant linear increasing or decreasing trends, significant unimodal (quadratic) trends or no significant altitudinal trend. The altitudinal variation in mean indicator values is discussed in relation to general environmental conditions such as bedrock, soil characteristics, topography, summer temperature, light, snow and distribution of major vegetation types. The main differences between the altitudinal bands as shown by a PCA analysis indicate that the highest bands, representing the high alpine zone (more than 1800 m a.s.l.) strongly differ from the others. The altitudinal gradient is mainly associated with variation in temperature, nitrogen indicators and some of the Raunkiaer life forms (primarily the Phanerophytes, Nanophanerophytes, Geophytes and Therophytes). The two tested temperature indicator systems tested were highly linearly correlated, but the altitudinal variation in respiration value followed the general temperature lapse rate better than the Ellenberg temperature indicator value. Indicators of high soil moisture have their optima at intermediate altitudes. The uppermost bands in Aurland show lower mean temperature indicator values and a higher snow indicator value compared to bands at the same altitude in Jotunheimen. This may partly be explained as a result of the Massenerhebung effect. Relationships between altitudinal distribution patterns of some vascular plants in Aurland and their Ellenberg temperature indicator value indicate that the values should be revised to better suit Norwegian conditions.

Natural avalanche disturbance shapes plant diversity and species composition in subalpine forest belt

AbstractBackground: Disturbances by avalanches have created unique habitats for animals and plants in subalpine ecosystems worldwide, but at the same time avalanches can pose a major threat to humans. Thus, avalanches are suppressed by means of avalanche barriers to protect settlements and infrastructures in populated areas of the European Alps. As a consequence, the disturbance regime in avalanche tracks has fundamentally changed.Methods: In the present study we address ecological consequences of avalanche suppression on plant diversity. We analysed plant diversity and species composition in recent and old avalanche tracks with and without avalanche suppression and in undisturbed adjacent forests at high and low elevations.Results: The number of species was higher in both active and inactive avalanche tracks as compared to undisturbed subalpine forest. The species composition indicated a wider range of ecological niches in active than in inactive avalanche tracks. The vegetation from active tracks showed lower indicator values for temperature and nitrogen availability. The proportion of alpine species was lower in formerly active tracks.Conclusions: The conditions that exist in active avalanche tracks increase plant diversity in relation to undisturbed forest. In the few decades following avalanche suppression, species composition changes in tracks from which avalanches have been excluded. Continued suppression of avalanche disturbance may lead to a decline in plant and habitat diversity. Avalanche disturbance can exert an important influence on the biodiversity of subalpine forests and provide important habitats. Anthropogenic changes in the natural regime of avalanche disturbance are likely to contribute significantly to future landscape changes in subalpine forests.

The geographical relationships of British and Irish vascular plants

Classifications of British and Irish vascular plants into floristic elements are reviewed. Only H.C. Watson and J.R. Matthews have attempted to devise a more or less comprehensive classification, based on the British range of the species (Watson) or the European distribution (Matthews). A new classification of 1481 native species is presented, based on their range in the Northern Hemisphere. Species are classified by their occurrence in one or more major biomes (Arctic, Boreal, Temperate, Southern) and their longitudinal distribution (Oceanic, Suboceanic, European, Eurosiberian, Eurasian, Circumpolar). The distribution of species in the floristic elements is illustrated by coincidence maps for the British Isles and Europe. The British and Irish flora is dominated by Boreo-temperate, Temperate and Southern-temperate species, with the Temperate species being the most numerous. Species with continental distributions (i.e. species which are rarer than expected in western Europe) are listed; most of these are in the Boreo-temperate and Temperate elements. The floristic elements are discussed in relation to the life-form spectra, habitat preferences and altitudinal limits of the component species, and analysed in terms of Ellenberg indicator values for temperature and continentality. The new classification is compared with that of Matthews. An additional 48 species which are endemic to the British Isles are listed. The scope for extending this method of classification to other organisms and for adapting it for use outside the British Isles is discussed.

The geographical relationships of British and Irish vascular plants

Classifications of British and Irish vascular plants into floristic elements are reviewed. Only H.C. Watson and J.R. Matthews have attempted to devise a more or less comprehensive classification, based on the British range of the species (Watson) or the European distribution (Matthews). A new classification of 1481 native species is presented, based on their range in the Northern Hemisphere. Species are classified by their occurrence in one or more major biomes (Arctic, Boreal, Temperate, Southern) and their longitudinal distribution (Oceanic, Suboceanic, European, Eurosiberian, Eurasian, Circumpolar). The distribution of species in the floristic elements is illustrated by coincidence maps for the British Isles and Europe. The British and Irish flora is dominated by Boreo-temperate, Temperate and Southern-temperate species, with the Temperate species being the most numerous. Species with continental distributions (i.e. species which are rarer than expected in western Europe) are listed; most of these are in the Boreo-temperate and Temperate elements. The floristic elements are discussed in relation to the life-form spectra, habitat preferences and altitudinal limits of the component species, and analysed in terms Ellenberg indicator values for temperature and continentality. The new classification is compared with that of Matthews. An additional 48 species which are endemic to the British Isles are listed. The scope for extending this method of classification to other organisms and for adapting it for use outside the British Isles is discussed.