Tree migration-rates : narrowing the gap between inferred post-glacial rates and projected rates

Faster-than-expected post-glacial migration rates of trees have puzzled ecologists for a long time. In Europe, post-glacial migration is assumed to have started from the three southern European peninsulas (southern refugia), where large areas remained free of permafrost and ice at the peak of the last glaciation. However, increasing palaeobotanical evidence for the presence of isolated tree populations in more northerly microrefugia has started to change this perception. Here we use the Northern Eurasian Plant Macrofossil Database and palaeoecological literature to show that post-glacial migration rates for trees may have been substantially lower (60–260 m yr–1) than those estimated by assuming migration from southern refugia only (115–550 m yr–1), and that early-successional trees migrated faster than mid- and late-successional trees. Post-glacial migration rates are in good agreement with those recently projected for the future with a population dynamical forest succession and dispersal model, mainly for early-successional trees and under optimal conditions. Although migration estimates presented here may be conservative because of our assumption of uniform dispersal, tree migration-rates clearly need reconsideration. We suggest that small outlier populations may be a key factor in understanding past migration rates and in predicting potential future range-shifts. The importance of outlier populations in the past may have an analogy in the future, as many tree species have been planted beyond their natural ranges, with a more beneficial microclimate than their regional surroundings. Therefore, climate-change-induced range-shifts in the future might well be influenced by such microrefugia

Towards European climate risk surfaces: the extent and distribution of analogous and non-analogous climates 1931-2100

Aim Climate is an important determinant of species distributions. We assess different aspects of risk arising from future climate change by quantifying changes in the spatial distribution of future climatic conditions compared with the recent past. Location Europe. Methods A 10' × 10' resolution gridded data set of five climate variables was used to calculate expected changes to the area, distance and direction of 1931–60 climatic conditions under the HadCM3 climate model for four future climate scenarios based on different rates of greenhouse gas emissions (SRES scenarios). Three levels of tolerance ranges determined the thresholds for which future conditions are considered analogous to 1931–60 (pre-warming) conditions. Results For many parts of Europe, areas with pre-warming analogous climate conditions will be smaller and further away in the future than they are now. For any location in Europe, areas with pre-warming analogous mean annual temperature conditions will, on average, be reduced between 23.7% (B1 scenario) and 49.7% (A1FI scenario) by 2100 when assuming a medium tolerance range. The mean distance to these areas will, on average, increase between 272 km (B1) and 645 km (A1FI). These changes are more pronounced for temperature than for water availability variables and also for narrow tolerance ranges compared to wide tolerance ranges. Using a combined measure of both temperature and precipitation variables, areas with prewarming analogous conditions are predicted to be in a more northeasterly direction in the future, but there are considerable regional differences within Europe. Main conclusions The results suggest that, for some parts of Europe, the loss of area with any suitable climatic conditions represents the greatest risk to biodiversity, but in other regions the distances that species may have to move to reach suitable climatic conditions may be a greater problem. Quantifying the distance and direction in analyses of change of climatically suitable areas can add additional information for climate change risk assessments

Quantifying components of risk for European woody species under climate change

Estimates of species extinction risk under climate change are generally based on differences in present and future climatically suitable areas. However, the locations of potentially suitable future environments (affecting establishment success), and the degree of climatic suitability in already occupied and new locations (affecting population viability) may be equally important determinants of risk. A species considered to be at low risk because its future distribution is predicted to be large, may actually be at high risk if these areas are out of reach, given the species' dispersal and migration rates or if all future suitable locations are only marginally suitable and the species is unlikely to build viable populations in competition with other species. Using bioclimatic models of 17 representative European woody species, we expand on current ways of risk assessment and suggest additional measures based on (a) the distance between presently occupied areas and areas predicted to be climatically suitable in the future and (b) the degree of change in climatic suitability in presently occupied and unoccupied locations. Species of boreal and temperate deciduous forests are predicted to face higher risk from loss of climatically suitable area than species from warmer and drier parts of Europe by 2095 using both the moderate B1 and the severe A1FI emission scenario. However, the average distance from currently occupied locations to areas predicted suitable in the future is generally shorter for boreal species than for southern species. Areas currently occupied will become more suitable for boreal and temperate species than for Mediterranean species whereas new suitable areas outside a species' current range are expected to show greater increases in suitability for Mediterranean species than for boreal and temperate species. Such additional risk measures can be easily derived and should give a more comprehensive picture of the risk species are likely to face under climate change

Climate change and health and social care: Defining future hazard, vulnerability and risk for infrastructure systems supporting older people’s health care in England

Health and social care systems (including the care needs of the population and infrastructures providing health and social care) are likely to be influenced by climate change, in particular by the increasing frequency and severity of weather-related hazards such as floods and heatwaves. Coldwaves will also continue to be challenging in the foreseeable future. Protecting people’s health and wellbeing from the impacts of climate change is especially important for older people, as they are particularly vulnerable to climate-related hazards. In addition, the proportion of people aged 65 and over is projected to increase significantly. This paper addresses these issues through a discussion of our work to map variations across England in future hazards, vulnerability and risk. We explain how this mapping has been used to identify areas of the country where the built infrastructure serving the older age group might be most severely impacted by climate-related events over the next 20–30 years and where planning for adaptation and resilience is most urgently required. Based on a review of research on the links between extreme weather events and their impacts on older people’s health and the care services on which they depend, we developed operational definitions of extreme weather-related hazards likely to place particular pressure on health and social care systems that are essential for older people’s health and wellbeing. We consider ways to relate these to the latest climate projections for the 2030s from the UK Climate Impacts Programme (UKCP09); river and coastal flooding projections for the 2050s from the 2004 UK Government’s Foresight Flood and Coastal Defence Project (Environment Agency, 2004); and demographic projections for 2031 produced by the Office for National Statistics, UK. The research highlights the complexity of undertaking future hazard and vulnerability assessments. Key challenges include: how to define future hazards associated with climate change; how to predict and interpret future socio-demographic conditions contributing to vulnerability; and how geographical variability in hazards and vulnerabilities may combine to produce risks at the local level. In contrast to a number of more local studies which have focused on the vulnerability of urban populations to the impact of climate change (particularly heatwaves), the findings highlight the potential vulnerability of older populations in more rural regions (often in coastal areas) to a range of extreme weather-related hazards in both the North and South of England

Parallel declines in pollinators and insect-pollinated plants in Britain and the Netherlands

Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species

An integrated analysis of 33 Eucalyptus trials linking the onset of competition-induced tree growth suppression with management, physiographic and climatic factors

One of the greatest difficulties associated with controlling competitive vegetation during the establishment of eucalypts relates to the timing and planning of `weeding' operations. This may be due to site related variability in vegetation species distribution and abundance, climatic conditions and methods of site preparation. Using data from 33 eucalypt vegetation management trials, multivariate statistical techniques were used to determine whether any climatic, physiographic or management related variables could be related to the time taken for competition-induced tree growth suppression to occur. Altitude, the method of site preparation (burning versus not burning) and the interaction between these two factors were significantly related to the timing of tree growth suppression. Regardless of the method of site preparation, the onset of competition-induced tree growth suppression occurred earlier at lower altitudes, where the vegetation was more diverse and vigorous. At higher altitudes, burning appears to stimulate the earlier growth of vegetation, reducing the time for competition-induced tree growth suppression to occur.Une analyse intégrée de 33 essais avec des eucalyptus reliant le début de la baisse de croissance due à la compétition avec la gestion des peuplements, les facteurs physiographiques et climatiques. Une des grandes difficultés pour obtenir un contrôle de la végétation concurrentielle pendant l'installation de plantations d'eucalyptus est liée à la planification des opérations de désherbage. La difficulté provient de la variabilité de distribution et d'abondance des espèces qui constituent la végétation, des conditions climatiques et des méthodes de préparation du terrain. Des données de 33 essais de gestion de la végétation concurrente en plantation d'Eucalyptus ont été analysées avec des techniques statistiques multivariées pour identifier les variables climatiques, physiographiques ou de gestion susceptibles d'influencer l'apparition du ralentissement de croissance par la compétition herbacée. L'altitude, la méthode de préparation du terrain (brûlis ou non brûlis) et l'interaction entre ces deux facteurs ont eu un effet significatif sur ce ralentissement. Indépendamment de la méthode de préparation du terrain, le ralentissement de croissance se produisait plus précocement à basse altitude, là où la végétation était plus variée et plus vigoureuse. À plus haute altitude, le brûlis semble stimuler une croissance plus précoce de la végétation herbacée, en favorisant ainsi le ralentissement de la croissance des arbres