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Warmer Climate (warmer + climate)
Selected AbstractsFrom introduction to the establishment of alien species: bioclimatic differences between presence and reproduction localities in the slider turtleDIVERSITY AND DISTRIBUTIONS, Issue 1 2009Gentile Francesco Ficetola ABSTRACT Aim, Understanding the factors determining the transition from introduction of aliens to the establishment of invasive populations is a critical issue of the study of biological invasions, and has key implications for management. Differences in fitness among areas of introduction can define the zones where aliens become invasive. The American slider turtle Trachemys scripta has been introduced worldwide, and has negative effects on freshwater communities, but only a subset of introduced populations breed successfully. We used species distribution models to assess the factors influencing the slider distribution in Italy, by analysing bioclimatic features that can cause the transition from presence of feral adults to breeding populations. We also evaluated whether climate change might increase the future suitability for reproduction. Location,, Central and Northern Italy. Methods,, The distribution of slider turtle was obtained from the literature, unpublished reports and field surveys. We used Maxent to build bioclimatic models. Results,, Reproductive populations are associated to a clear bioclimatic envelope with warmer climate, more solar radiation and higher precipitations than populations where reproduction is not observed. Several Mediterranean areas currently have climatic features suitable for sliders. Scenarios of climate change predict the expansion of these areas. In the near future (2020), the proportion of populations in areas suitable for reproduction will dramatically increase. Main conclusion,, Our study shows that bioclimatic differences can determine the areas where aliens become invaders. Management should be focused to these source areas. However, climate change can increase fitness in the future, and therefore the interactions between climate change and fitness can boost the invasiveness of this alien species. [source] Modeling past and future alpine permafrost distribution in the Colorado Front RangeEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2005Jason R. Janke Abstract Rock glaciers, a feature associated with at least discontinuous permafrost, provide important topoclimatic information. Active and inactive rock glaciers can be used to model current permafrost distribution. Relict rock glacier locations provide paleoclimatic information to infer past conditions. Future warmer climates could cause permafrost zones to shrink and initiate slope instability hazards such as debris flows or rockslides, thus modeling change remains imperative. This research examines potential past and future permafrost distribution in the Colorado Front Range by calibrating an existing permafrost model using a standard adiabatic rate for mountains (0·5 °C per 100 m) for a 4 °C range of cooler and warmer temperatures. According to the model, permafrost currently covers about 12 per cent (326·1 km2) of the entire study area (2721·5 km2). In a 4 °C cooler climate 73·7 per cent (2004·4 km2) of the study area could be covered by permafrost, whereas in a 4°C warmer climate almost no permafrost would be found. Permafrost would be reduced severely by 93·9 per cent (a loss of 306·2 km2) in a 2·0 °C warmer climate; however, permafrost will likely respond slowly to change. Relict rock glacier distribution indicates that mean annual air temperature (MAAT) was once at least some 3·0 to 4·0 °C cooler during the Pleistocene, with permafrost extending some 600,700 m lower than today. The model is effective at identifying temperature sensitive areas for future monitoring; however, other feedback mechanisms such as precipitation are neglected. Copyright © 2005 John Wiley & Sons, Ltd. [source] Topographic controls on spatial patterns of conifer transpiration and net primary productivity under climate warming in mountain ecosystemsECOHYDROLOGY, Issue 4 2009C. Tague Abstract The response of forests to a warmer climate depends upon the direct impacts of temperature on forest ecophysiology and indirect effects related to a range of biogeophysical processes. In alpine regions, reduced snow accumulation and earlier melt of seasonal snowpacks are expected hydrologic consequences of warming. For forests, this leads to earlier soil moisture recharge, and may increase summer drought stress. At the same time, increased air temperature alters plant net primary productivity. Most models of climate change impacts focus either on hydrologic behaviour or ecosystem structure or function. In this study we address the interactions between them. We use a coupled model of eco-hydrologic processes to estimate changes in evapotranspiration and vegetation productivity under temperature warming scenarios. Results from Yosemite National Park, in the California Sierra Nevada, suggest that for most snow-dominated elevations, the shift in the timing of recharge is likely to lead to declines in productivity and vegetation water use, even with increased water-use efficiency associated with elevated atmospheric CO2 concentrations. The strength of this effect, however, depends upon interactions between several factors that vary substantially across elevation gradients, including the initial timing of melt relative to the summer growing season, vegetation growth, and the extent to which initial vegetation is water-limited or temperature-limited. These climate-driven changes in vegetation water use also have important implications for summer streamflow. Results from this analysis provide a framework that can be used to develop strategic measurement campaigns and to extrapolate from local measurements of vegetation responses to watershed scale patterns. Copyright © 2009 John Wiley & Sons, Ltd. [source] Spatial and temporal variability of the Aleutian climateFISHERIES OCEANOGRAPHY, Issue 2005SERGEI N. RODIONOV Abstract The objective of this paper is to highlight those characteristics of climate variability that may pertain to the climate hypothesis regarding the long-term population decline of Steller sea lions (Eumetopias jubatus). The seasonal changes in surface air temperature (SAT) across the Aleutian Islands are relatively uniform, from 5 to 10°C in summer to near freezing temperatures in winter. The interannual and interdecadal variations in SAT, however, are substantially different for the eastern and western Aleutians, with the transition found at about 170°W. The eastern Aleutians experienced a regime shift toward a warmer climate in 1977, simultaneously with the basin-wide shift in the Pacific Decadal Oscillation (PDO). In contrast, the western Aleutians show a steady decline in winter SATs that started in the 1950s. This cooling trend was accompanied by a trend toward more variable SAT, both on the inter- and intra-annual time scale. During 1986,2002, the variance of winter SATs more than doubled compared to 1965,1985. At the same time in Southeast Alaska, the SAT variance diminished by half. Much of the increase in the intra-seasonal variability for the western Aleutians is associated with a warming trend in November and a cooling trend in January. As a result, the rate of seasonal cooling from November to January has doubled since the late 1950s. We hypothesize that this trend in SAT variability may have increased the environmental stress on the western stock of Steller sea lions and hence contributed to its decline. [source] Palsas in Härjedalen, Sweden: 1910 and 1998 ComparedGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2000Tomas Nihlén In 1998 an area near Helagsfjället in Härjedalen was investigated in an attempt to relocate palsas discovered by the botanist Harry Smith in 1910. Several small palsa-like features with ice cores were detected. The palsas were found on an almost flat peat bog at 950 m, 3 km NW of Helagsfjället. Five clearly elevated mounds and some indistinct ones with palsa-like features were traced. The five mounds were about 0.6 m high and had an area of about 2 × 3 m. One of the mounds was examined in more detail. At a depth of 0.3 m in the peat an ice body with a hard ice core was found. This location is the most southerly area known with occurrence of palsa-like forms in Sweden at the present time. In spite of a warmer climate towards the latter part of this century, palsa-like features have survived in this area. The mean annual temperature barely fits the criterion for palsa formation while the mean annual precipitation is too high as compared with the general assumptions. The palsa formation is probably dependent on strong winds thinning out the snowcover. [source] Impacts of climate change on fire activity and fire management in the circumboreal forestGLOBAL CHANGE BIOLOGY, Issue 3 2009MIKE FLANNIGAN Abstract Forest fires are a significant and natural element of the circumboreal forest. Fire activity is strongly linked to weather, and increased fire activity due to climate change is anticipated or arguably has already occurred. Recent studies suggest a doubling of area burned along with a 50% increase in fire occurrence in parts of the circumboreal by the end of this century. Fire management agencies' ability to cope with these increases in fire activity is limited, as these organizations operate with a narrow margin between success and failure; a disproportionate number of fires may escape initial attack under a warmer climate, resulting in an increase in area burned that will be much greater than the corresponding increase in fire weather severity. There may be only a decade or two before increased fire activity means fire management agencies cannot maintain their current levels of effectiveness. [source] Combined effects of elevated temperatures and reduced leaf litter quality on the life-history parameters of a saprophagous macroarthropodGLOBAL CHANGE BIOLOGY, Issue 1 2009JEAN-FRANCOIS DAVID Abstract Because soil macroinvertebrates strongly modify decomposition processes, it is important to know how their abundance will respond to global change. We investigated in laboratory microcosms, the effects of elevated temperatures and reduced leaf litter quality on the life-history traits of a saprophagous macroarthropod (development time, growth, survival and reproduction). Millipedes (Polydesmus angustus) from an Atlantic temperate forest were reared throughout their life cycle (,16 months) under two temperature regimes differing on average by 3.3 °C; in a factorial design, they were fed either on Atlantic leaf litter or on Mediterranean leaf litter with a higher C : N ratio; humidity was consistently high. The components of the population growth rate (r) were affected positively by the temperature rise and negatively by the switch from Atlantic to Mediterranean leaf litter. When both treatments were combined, litter effects offset temperature effects. These results show that the short-term response of saprophagous macroarthropods to warming is positive but depends on the availability of high-quality litter, which is difficult to predict in the global change context. In a parallel experiment, conspecific millipedes from a Mediterranean population, which have evolved for a long time in a warmer climate and on poor-quality litter, were reared at elevated temperatures on Mediterranean leaf litter. All components of r were higher than in the Atlantic population under the same conditions. This suggests that in the longer term, macroarthropods can overcome detrimental trophic interactions. Based on our study and the literature, we conclude that for decades the positive effects of warming on saprophagous macrofauna should exceed the negative effects of changes in litter quality. The abundance of those organisms in temperate forests could increase, which is confirmed by latitudinal patterns in Europe. Studies aimed at predicting the impacts of global change on decomposition will need to consider interactions with soil macroinvertebrates. [source] Vegetation gradients in Atlantic Europe: the use of existing phytosociological data in preliminary investigations on the potential effects of climate change on British vegetationGLOBAL ECOLOGY, Issue 3 2000J. C. Duckworth Abstract 1This 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. 2Data 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. 3Climate 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. 4The 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. 5Those 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. 6The 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. [source] Sensitivity analysis of snow patterns in Swiss ski resorts to shifts in temperature, precipitation and humidity under conditions of climate changeINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2009Bastienne Uhlmann Abstract The value of snow as a resource has considerably increased in Swiss mountain regions, in particular in the context of winter tourism. In the perspective of a warming climate, it is thus important to quantify the potential changes in snow amount and duration that could have large repercussions on the economy of ski resorts. Because of the fine spatial variability of snow, the use of a Surface Energy Balance Model (SEBM) is adequate to simulate local snow cover evolution. A perturbation method has been developed to generate plausible future meteorological input data required for SEBM simulations in order to assess the changes in snow cover patterns. Current and future snow depths have also been simulated within the ski areas themselves. The results show a large decrease of the snow depths and duration, even at high elevation in a warmer climate and emphasize the sensitivity of snow to topographical characteristics of the resorts. The most vulnerable areas would be the Western regions of Switzerland or the Eastern Prealps whereas the Central Alps or Valais would be less affected. The study highlights the fact that not only the altitude of a domain but also its exposure, localization inland and slope gradients need to be taken into account when evaluating current and future snow depths. This method enables a precise assessment of the snow pattern over a small area. Copyright © 2008 Royal Meteorological Society [source] Enhanced resolution modelling study on anthropogenic climate change: changes in extremes of the hydrological cycleINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2002Reinhard Voss Abstract Changes in variability and extremes of the hydrological cycle are studied in two 30 year simulations using a general circulation model at high horizontal resolution. The simulations represent the present-day climate and a period in which the radiative forcing corresponds to a doubling of the present-day concentrations of atmospheric greenhouse gases. In most regions and seasons the probability density function of daily precipitation experiences a stretching associated with a higher probability of heavy precipitation events in the warmer climate. Whereas extremely long wet spells show only moderate changes, the extremely long dry spells are extended at middle latitudes over most land areas. At high latitudes the changes in annual maximum river runoff are mainly controlled by changes in snow budget. Eight out of 14 selected major rivers show a statistically significant change in 10 year return values of the annual maximum discharge. In two cases a significant decrease is found and in six cases there is a significant increase. Copyright © 2002 Royal Meteorological Society [source] Effects of climate on the growth of exotic and indigenous trees in central ZambiaJOURNAL OF BIOGEOGRAPHY, Issue 1 2005E. N. Chidumayo Abstract Aim, Climate change has far-reaching effects on species and ecosystems. The aims of this study were to determine how climate factors affect the growth pattern of indigenous and exotic trees in Zambia and to predict tree growth responses to a warmer climate with the use of mathematical models. Location, Two savanna sites in central Zambia. Methods, Diameter at breast height (1.3 m above ground, d.b.h.) of 91 permanently marked trees belonging to three indigenous and four exotic species was measured fortnightly for periods of 1,2 years from 1998 to 2003. Correlation and regression analysis was used to determine the effect of climate factors (minimum, maximum and average temperature and rainfall) on monthly daily d.b.h. increment of each species. Regression models were used to predict the growth behaviour of trees under a 0.5 °C warmer climate. Results, Interactions between temperature and rainfall explained 60,98% of the variation in d.b.h. increment in all the tree species, except the exotic Eucalyptus grandis. For deciduous species, stem expansion was delayed by 2,12 weeks following leaf-flush and d.b.h. increment peaked during the rainy season. Evergreen and deciduous species could not be separated on the basis of annual d.b.h. increment because the higher growth rates of deciduous species compensated for the shorter growing period. Mathematical models predicted slight changes in d.b.h. growth pattern under a 0.5 °C warmer climate in five of the seven species. Significant changes in d.b.h. growth patterns were predicted in the indigenous Bridelia micrantha and exotic Gmelina arborea under a warmer climate. However, models failed to adequately represent potential soil water stress that might result from changes in tree growth patterns and a warmer climate. Main conclusions, Climate factors explained a large proportion of the variation in diameter growth of both indigenous and exotic trees, rendering it possible to model tree growth patterns from climate data. Tree growth models suggest that a rise in temperature of 0.5 °C is unlikely to induce significant changes in the growth behaviour of the majority of the studied species. However, because the growth behaviour of some species may be substantially affected by climate change, it is recommended that strategies for the future production of such climate-sensitive trees should incorporate aspects of climate change. [source] Is the large size of the pinna of the ear of the European hare (Lepus europaeus) due to its role in thermoregulation or in anterior capital shock absorption?JOURNAL OF MORPHOLOGY, Issue 6 2010Philip Stott Abstract Large pinnae are characteristic of the Leporids, and the pinna is known to have a thermoregulatory role. Another role has been hypothesized for the pinna of Lepus spp., as a part of a suspensory system for the greater portion of the head, absorbing shock that might otherwise interfere with vision during high-speed locomotion. We compared the lengths of the pinnae of adult European hares Lepus europaeus from the source population in the cooler climate of England with those of the introduced population in the warmer climate of Australia, and we compared the lengths of the pinnae of hares that had grown in cooler weather with those that had grown in warmer weather. There were no significant differences between each of the comparisons, indicating that the size of the pinna is not determined by thermoregulatory requirements at rest. We compared the growth in length of the pinnae and the legs with growth in body mass, and growth in the mass of the pinnae with the masses of the head and the eyeballs, and found support for the suspension hypothesis. We suggest that the rapid growth of the pinna is because visual acuity is a function of absolute eye size, not relative eye size, yet juvenile hares are subject to the same predator pressure as adult hares, and equally need to maximize visual acuity while running at high speeds in dim light. We believe that the large size of the pinna is determined by its role in anterior capital suspension, not in thermoregulation. J. Morphol., 2010. © 2010 Wiley-Liss, Inc. [source] Late Quaternary vegetation, climate and fire dynamics inferred from the El Tiro record in the southeastern Ecuadorian Andes,JOURNAL OF QUATERNARY SCIENCE, Issue 3 2008Holger Niemann Abstract In order to study the stability and dynamics of mountain rainforest and paramo ecosystems, including the biodiversity of these ecosystems, the Holocene and late Pleistocene climate and fire variability, and human impact in the southeastern Ecuadorian Andes, we present a high-resolution pollen record from El Tiro Pass (2810,m elevation), Podocarpus National Park. Palaeoenvironmental changes, investigated by pollen, spores and charcoal analysis, inferred from a 127,cm long core spanning the last ca. 21,000,cal. yr BP, indicate that grass-paramo was the main vegetation type at the El Tiro Pass during the late Pleistocene period. The grass-paramo was rich in Poaceae, Plantago rigida and Plantago australis, reflecting cold and moist climatic conditions. During the early Holocene, from 11,200 to 8900,cal. yr BP, subparamo and upper mountain rainforest vegetation expanded slightly, indicating a slow warming of climatic conditions during this period. From 8900 to 3300,cal. yr BP an upper mountain rainforest developed at the study site, indicated by an increase in Hedyosmun, Podocarpaceae, Myrsine and Ilex. This suggests a warmer climate than the present day at this elevation. The modern subparamo vegetation became established since 3300,cal. yr BP at El Tiro Pass. Fires, probably anthropogenic origin, were very rare during the late Pleistocene but became frequent after 8000,cal. yr BP. Copyright © 2007 John Wiley & Sons, Ltd. [source] Alpine flora dynamics , a critical review of responses to climate change in the Swedish Scandes since the early 1950sNORDIC JOURNAL OF BOTANY, Issue 4 2010Leif Kullman Reports about changes of alpine plant species richness over the past 60 years in the Swedish Scandes are reviewed, synthesized and updated with data from recent reinventories. Methodologically, this endeavour is based on resurveys of the floristic composition on the uppermost 20 m of four high-mountain summits. The key finding is that the species pool has increased by 60,170% since the 1950s and later. Some of the invading species are new to the alpine tundra, with more silvine and thermophilic properties than the extant alpine flora. Not a single species of the original flora has disappeared from any of the summits. This circumstance is discussed in perspective of widespread expectations of pending temperature-driven extinction of alpine species in an alleged future warmer climate. These progressive changes coincided with distinct warming (summer and winter) since the late 1980s. During a short cooler period (1974,1994), the species numbers decreased and the upper elevational limits of some ground cover species descended. Thus, discernible responses, concurrent with both warming and cooling intervals, sustain a strong causal link between climate variability and alpine plant species richness. Methodologically, plot-less revisitation studies of the present kind are beset with substantial uncertainties, which may overstate floristic changes over time. However, it is argued here that carefully executed and critically interpreted, no other method can equally effectively sense the earliest phases of plant invasions into alpine vegetation. [source] Restoration of Midwestern U.S. Savannas: One Size Does Not Fit AllRESTORATION ECOLOGY, Issue 6 2009Connie L. Dettman Abstract Lowland savannas are a rare variant of Midwestern United States savanna occurring on alluvial soils, for which reference information is sparse. To evaluate the appropriateness of using upland savanna as a surrogate source of reference information for lowland savanna, we studied a pre-Euro-American lowland savanna using original U.S. Public Land Survey data and other historical records. Historical vegetation was reconstructed and compared among upland savannas, lowland savannas, and lowland forests; we also evaluated potential disturbance dynamics maintaining these systems. We found that all three communities were dominated by members of the genus Quercus but also had extensive representation by many other tree species, especially notable for savannas in this region. There were no clear size,density relationships for species in the genus Quercus, indicating that these historical savannas were not characterized exclusively by large, scattered oak trees but rather by trees of many oak species and nonoak species in a wide range of size classes. Both upland and lowland savannas also contained a substantial shrub component. We found no evidence that lowland savannas were maintained by flooding, although the uneven-aged canopy structure suggested that periodic disturbance occurred. Restoration of lowland savanna in this region should include provisions for maintaining nonoak species and shrubs, with disturbance timed to maintain an uneven-aged canopy structure. Although the appropriateness of historical data in the face of climate change may be questionable, in this region, a warmer climate may actually help promote the "oak parkland" that was present from 8,000 BP up to Euro-American settlement. [source] DIGITAL CEMENTUM LUMINANCE ANALYSIS AND THE HAUA FTEAH HOMININS: HOW SEASONALITY AND SEASON OF USE CHANGED THROUGH TIME,ARCHAEOMETRY, Issue 4 2007C. M. WALL-SCHEFFLER The importance of environmental seasonality and the seasonal cycling of resources to human populations make studies of human responses to seasonality useful to test hypotheses about short- and long-term changes in human behaviour. This paper utilizes digital dental cementum luminance analysis in order to better understand patterns of the seasons of death of Ammotragus lervia at Haua Fteah, Cyrenaica, and to test whether long-term climatic changes can be detected in dental cement. The overall pattern of the season of death of A. lervia at Haua Fteah is that of year-round utilization, with a slight increase over time in A. lervia use during the growth period/summer time. The use of digital cementum luminance analysis (DCLA) to detect changes in the seasonal differences between temperatures indicates a trend for increased seasonality in temperature over the past 40 000 years at Haua Fteah. Furthermore, DCLA patterns in the more recent assemblages indicate a shift to a warmer climate from Marine Oxygen Isotope Stage (MIS) 3 to MIS 1. [source] Modeling past and future alpine permafrost distribution in the Colorado Front RangeEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2005Jason R. Janke Abstract Rock glaciers, a feature associated with at least discontinuous permafrost, provide important topoclimatic information. Active and inactive rock glaciers can be used to model current permafrost distribution. Relict rock glacier locations provide paleoclimatic information to infer past conditions. Future warmer climates could cause permafrost zones to shrink and initiate slope instability hazards such as debris flows or rockslides, thus modeling change remains imperative. This research examines potential past and future permafrost distribution in the Colorado Front Range by calibrating an existing permafrost model using a standard adiabatic rate for mountains (0·5 °C per 100 m) for a 4 °C range of cooler and warmer temperatures. According to the model, permafrost currently covers about 12 per cent (326·1 km2) of the entire study area (2721·5 km2). In a 4 °C cooler climate 73·7 per cent (2004·4 km2) of the study area could be covered by permafrost, whereas in a 4°C warmer climate almost no permafrost would be found. Permafrost would be reduced severely by 93·9 per cent (a loss of 306·2 km2) in a 2·0 °C warmer climate; however, permafrost will likely respond slowly to change. Relict rock glacier distribution indicates that mean annual air temperature (MAAT) was once at least some 3·0 to 4·0 °C cooler during the Pleistocene, with permafrost extending some 600,700 m lower than today. The model is effective at identifying temperature sensitive areas for future monitoring; however, other feedback mechanisms such as precipitation are neglected. Copyright © 2005 John Wiley & Sons, Ltd. [source] Adaptation, migration or extirpation: climate change outcomes for tree populationsEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 1 2008Sally N. Aitken Abstract Species distribution models predict a wholesale redistribution of trees in the next century, yet migratory responses necessary to spatially track climates far exceed maximum post-glacial rates. The extent to which populations will adapt will depend upon phenotypic variation, strength of selection, fecundity, interspecific competition, and biotic interactions. Populations of temperate and boreal trees show moderate to strong clines in phenology and growth along temperature gradients, indicating substantial local adaptation. Traits involved in local adaptation appear to be the product of small effects of many genes, and the resulting genotypic redundancy combined with high fecundity may facilitate rapid local adaptation despite high gene flow. Gene flow with preadapted alleles from warmer climates may promote adaptation and migration at the leading edge, while populations at the rear will likely face extirpation. Widespread species with large populations and high fecundity are likely to persist and adapt, but will likely suffer adaptational lag for a few generations. As all tree species will be suffering lags, interspecific competition may weaken, facilitating persistence under suboptimal conditions. Species with small populations, fragmented ranges, low fecundity, or suffering declines due to introduced insects or diseases should be candidates for facilitated migration. [source] Voltinism flexibility of a riverine dragonfly along thermal gradientsGLOBAL CHANGE BIOLOGY, Issue 3 2008ERIK BRAUNE Abstract Potential effects of future warming should be reflected in life history patterns of aquatic organisms observed in warmer climates or in habitats that are different in ambient temperature. In the special case of the dragonfly Gomphus vulgatissimus (L.) (Odonata: Gomphidae) previous research suggests that voltinism decreases from south to north. We analysed data on voltinism from 11 sample sites along a latitudinal gradient from about 44°N to 53°N, comprising small streams to medium-sized rivers. Furthermore, to simulate different conditions and to allow projections for future climate change scenarios, we developed a population dynamic model based on a projection matrix approach. The parameters of the model are dependent on temperature and day length. Our field results indicate a decrease in voltinism along the latitudinal gradient from southern to northern Europe and a corresponding increase of voltinism with higher temperatures. An increase in voltinism with width of the running water implies an effect of varying habitat temperature. Under the impact of global warming, our model predicts an increased development speed, particularly in the northern part of the latitudinal gradient, an extension of the northern range limit and changes in phenology of G. vulgatissimus, leading to an extension of the flight season in certain regions along the gradient. [source] Heat shock protein 101 effects in A. thaliana: genetic variation, fitness and pleiotropy in controlled temperature conditionsMOLECULAR ECOLOGY, Issue 6 2008S. J. TONSOR Abstract The Hsp100/ClpB heat shock protein family is ancient and required for high temperature survival, but natural variation in expression and its phenotypic effects is unexplored in plants. In controlled environment experiments, we examined the effects of variation in the Arabidopsis cytosolic AtHsp101 (hereafter Hsp101). Ten wild-collected ecotypes differed in Hsp101 expression responses across a 22 to 40 °C gradient. Genotypes from low latitudes expressed the least Hsp101. We tested fitness and pleiotropic consequences of varying Hsp101 expression in ,control' vs. mild thermal stress treatments (15/25 °C D/N vs. 15/25° D/N plus 3 h at 35 °C 3 days/week). Comparing wild type and null mutants, wt Columbia (Col) produced ~33% more fruits compared to its Hsp101 homozygous null mutant. There was no difference between Landsberg erecta null mutant NIL (Ler) and wt Ler; wt Ler showed very low Hsp101 expression. In an assay of six genotypes, fecundity was a saturating function of Hsp101 content, in both experimental treatments. Thus, in addition to its essential role in acquired thermal tolerance, Hsp101 provides a substantial fitness benefit under normal growth conditions. Knocking out Hsp101 decreased fruit production, days to germination and days to bolting, total dry mass, and number of inflorescences; it increased transpiration rate and allocation to root mass. Root : total mass ratio decayed exponentially with Hsp101 content. This study shows that Hsp101 expression is evolvable in natural populations. Our results further suggest that Hsp101 is primarily an emergency high-temperature tolerance mechanism, since expression levels are lower in low-latitude populations from warmer climates. Hsp101 expression appears to carry an important trade-off in reduced root growth. This trade-off may select for suppressed expression under chronically high temperatures. [source] Patterns of permafrost formation and degradation in relation to climate and ecosystemsPERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2007Y. L. Shur Abstract We develop a permafrost classification system to describe the complex interaction of climatic and ecological processes in permafrost formation and degradation that differentiates five patterns of formation: ,climate-driven'; ,climate-driven, ecosystem-modified'; ,climate-driven, ecosystem-protected'; ,ecosystem-driven'; and ,ecosystem-protected' permafrost. Climate-driven permafrost develops in the continuous permafrost zone, where permafrost forms immediately after the surface is exposed to the atmosphere and even under shallow water. Climate-driven, ecosystem-modified permafrost occurs in the continuous permafrost zone when vegetation succession and organic-matter accumulation lead to development of an ice-rich layer at the top of the permafrost. During warming climates, permafrost that has formed as climate-driven can occur in the discontinuous permafrost zone, where it can persist for a long time as ecosystem-protected. Climate-driven, ecosystem protected permafrost, and its associated ground ice, cannot re-establish in the discontinuous zone once degraded, although the near surface can recover as ecosystem-driven permafrost. Ecosystem-driven permafrost forms in the discontinuous permafrost zone in poorly drained, low-lying and north-facing landscape conditions, and under strong ecosystem influence. Finally, ecosystem-protected permafrost persists as sporadic patches under warmer climates, but cannot be re-established after disturbance. These distinctions are important because the various types react differently to climate change and surface disturbances. For example, climate-driven, ecosystem-modified permafrost can experience thermokarst even under cold conditions because of its ice-rich layer formed during ecosystem development, and ecosystem-driven permafrost is unlikely to recover after disturbance, such as fire, if there is sufficient climate warming. Copyright © 2007 John Wiley & Sons, Ltd. [source] Climate variables as predictors of basal metabolic rate: New equationsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2008Andrew W. Froehle Estimation of basal metabolic rate (BMR) and daily energy expenditure (DEE) in living humans and in fossil hominins can be used to understand the way populations adapt to different environmental and nutritional circumstances. One variable that should be considered in such estimates is climate, which may influence between-population variation in BMR. Overall, populations living in warmer climates tend to have lower BMR than those living in colder climates, even after controlling for body size and composition. Current methods of estimating BMR ignore climate, or deal with its effects in an insufficient manner. This may affect studies that use the factorial method to estimate DEE from BMR, when BMR is not measured but predicted using an equation. The present meta-analysis of published BMR uses stepwise regression to investigate whether the inclusion of climate variables can produce a generally applicable model for human BMR. Regression results show that mean annual temperature and high heat index temperature have a significant effect on BMR, along with body size, age and sex. Based on the regression analysis, equations predicting BMR from body size and climate variables were derived and compared with existing equations. The new equations are generally more accurate and more consistent across climates than the older ones. Estimates of DEE in living and fossil humans using the new equations are compared with estimates using previously published equations, illustrating the utility of including climate variables in estimates of BMR. The new equations derived here may prove useful for future studies of human energy expenditure. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||