Spring Temperatures (spring + temperature)

Distribution by Scientific Domains

Selected Abstracts

Inter- and intraspecific differences in climatically mediated phenological change in coexisting Triturus species

Abstract Climate and weather affect phenological events in a wide range of taxa, and future changes might disrupt ecological interactions. Amphibians are particularly sensitive to climate, but few studies have addressed climatically mediated change in the phenology of closely related species or sexes. Here, we test the hypothesis that changes in spring temperatures result in phenological change among Triturus, and we examine inter- and intraspecific differences in response. Coexisting populations of Triturus helveticus and Triturus vulgaris at Llysdinam pond in mid-Wales (53°12,59,N 3°27,3,W) were monitored using pitfall traps along a drift fence during 1981,1987, and again in 1997,2005. Spring temperature over the same period explained up to 74% of between-year variability in median arrival date, with a significant advance of 2,5 days with every degree centigrade increase. Changes were greater for males than females of both species, and greater for T. helveticus than T. vulgaris within sexes, resulting in an increasing temporal separation between arrivals of male T. helveticus and all other groups. These data illustrate for the first time how climatic change might have differential effects on sympatric species and on the two sexes. [source]

Spring temperatures in the Sagehen Basin, Sierra Nevada, CA: implications for heat flow and groundwater circulation

Abstract Heat flow in the Sierra Nevada, CA, is low despite its young geologic age. We investigate the possibility that advective heat transport by groundwater flow leads to an underestimate of heat flow in the Sierras based purely on borehole measurements. Using temperature and discharge measurements at springs in Sagehen Basin, we find that groundwater removes the equivalent of approximately 20,40 mW m,2 of geothermal heat from the basin. This is comparable with other heat flow measurements in the region and indicates that, in this basin, at least, groundwater does transport a significant amount of geothermal heat within the basin. Additionally, we use estimates of the mean residence time of water discharged at the springs along with hourly temperature records in springs to provide constraints on groundwater flow depths within the basin. An analytical model based on these constraints indicates that the heat removed by groundwater may represent 20% to >90% of the total heat flow in the basin. Without better constraints on the regional hydrogeology and the depth of circulation, we cannot determine whether the heat discharged at the springs represents a change in the mode of heat transfer, i.e. from conduction to advection at shallow depths (<100 m) or whether this is a component of heat transfer that should be added to measured conductive values. If the latter is true, and Sagehen Basin is representative of the Sierras, basal heat flow in the Sierra Nevada may be higher than previously thought. [source]

Spring phenology in boreal Eurasia over a nearly century time scale

Abstract It has been widely reported that tree leaves have tended to appear earlier in many regions of the northern hemisphere in the last few decades, reflecting climate warming. Satellite observations revealed an 8-day advance in leaf appearance date between 1982 and 1991 in northern latitudes. In situ observations show that leaf appearance dates in Europe have advanced by an average of 6.3 days from 1959 to 1996. Modelling of leaf appearance on the basis of temperature also shows a marked advance in temperate and boreal regions from 1955 to 2002. However, before 1955, reported studies of phenological variations are restricted to local scale. Modelling, ground observations and satellite observations are here combined to analyse phenological variations in Eurasian taiga over nearly a century. The trend observed by remote sensing consists mainly in a shift at the end of the 1980s, reflecting a shift in winter and spring temperature. In western boreal Eurasia, a trend to earlier leaf appearance is evident since the mid-1930s, although it is discontinuous. In contrast, the strong advance in leaf appearance detected over Central Siberia using satellite data in 1982,1991 is strengthened by late springs in 1983,1984; moreover, in this region the green-up timing has displayed successive trends with opposite signs since 1920. Thus, such strong trend is not unusual if considered locally. However, the recent advance is unique in simultaneously affecting most of the Eurasian taiga, the leaf appearance dates after 1990 being the earliest in nearly a century in most of the area. [source]

Estimating annual N2O emissions from agricultural soils in temperate climates

Caroline Roelandt
Abstract The Kyoto protocol requires countries to provide national inventories for a list of greenhouse gases including N2O. A standard methodology proposed by the Intergovernmental Panel on Climate Change (IPCC) estimates direct N2O emissions from soils as a constant fraction (1.25%) of the nitrogen input. This approach is insensitive to environmental variability. A more dynamic approach is needed to establish reliable N2O emission inventories and to propose efficient mitigation strategies. The objective of this paper is to develop a model that allows the spatial and temporal variation in environmental conditions to be taken into account in national inventories of direct N2O emissions. Observed annual N2O emission rates are used to establish statistical relationships between N2O emissions, seasonal climate and nitrogen-fertilization rate. Two empirical models, MCROPS and MGRASS, were developed for croplands and grasslands. Validated with an independent data set, MCROPS shows that spring temperature and summer precipitation explain 35% of the variance in annual N2O emissions from croplands. In MGRASS, nitrogen-fertilization rate and winter temperature explain 48% of the variance in annual N2O emissions from grasslands. Using long-term climate observations (1900,2000), the sensitivity of the models with climate variability is estimated by comparing the year-to-year prediction of the model to the precision obtained during the validation process. MCROPS is able to capture interannual variability of N2O emissions from croplands. However, grassland emissions show very small interannual variations, which are too small to be detectable by MGRASS. MCROPS and MGRASS improve the statistical reliability of direct N2O emissions compared with the IPCC default methodology. Furthermore, the models can be used to estimate the effects of interannual variation in climate, climate change on direct N2O emissions from soils at the regional scale. [source]

Effects of climatic change on the phenology of butterflies in the northwest Mediterranean Basin

Constantí Stefanescu
Abstract Phenological changes in response to climatic warming have been detected across a wide range of organisms. Butterflies stand out as one of the most popular groups of indicators of climatic change, given that, firstly, they are poikilothermic and, secondly, have been the subject of thorough monitoring programmes in several countries for a number of decades. Here we provide for the first time strong evidence of phenological change as a consequence of recent climatic warming in butterflies at a Spanish site in the northwest Mediterranean Basin. By means of the widely used Butterfly Monitoring Scheme methodology, three different phenological parameters were analysed for the most common species to test for trends over time and relationships with temperature and precipitation. Between 1988 and 2002, there was a tendency for earlier first appearance dates in all 17 butterfly species tested, and significant advances in mean flight dates in 8 out of 19 species. On the other hand, the shape of the curve of adult emergence did not show any regular pattern. These changes paralleled an increase of 1,1.5°C in mean February, March and June temperatures. Likewise, a correlation analysis indicated the strong negative effect of spring temperature on phenological parameters (i.e. higher temperatures tended to produce phenological advances), and the opposite effect of precipitation in certain months. In addition, there was some evidence to indicate that phenological responses may differ between taxonomic lineages or species with similar diets. We discuss the consequences that these changes may have on species' population abundances, especially given the expected increase in aridity in the Mediterranean Basin caused by current climatic warming. We predict that varying degrees of phenological flexibility may account for differences in species' responses and, for multivoltine species, predict strong selection favouring local seasonal adaptations such as diapause phenomena or migratory behaviour. [source]

The influence of the winter Arctic oscillation on the northern Russia spring temperature

Vladimir N. Kryjov
Abstract Correlation and trend analyses are applied to examine relationships between the northern Russia snow/ice season surface air temperature (SAT) and winter circulation, represented by the January,March Arctic oscillation (AO) index. The 1935,99 series of winter and spring monthly SAT from five stations are used, with the winter season being defined as January,March and the spring season being defined specifically for each station in accordance with local snow/ice season duration from April,May through April,July. It is shown that the influence of the winter circulation on SAT is evident at least until the end of snow/ice season, which suggests that this influence is implemented via feedbacks provided by snow and sea ice. The winter AO accounts for some 25,50% (15,20%) of the winter (spring) SAT variance. More than 50% of the 30 year (1968,97) trends in both winter and spring SAT for northwestern Russia and more than 40% for northwestern Siberia are linearly correlated with the winter AO. It is proposed that in the Arctic Ocean regions, where snow and ice do not melt completely, the winter AO influence on SAT is likely to be evident at least until the next year's winter. Copyright © 2002 Royal Meteorological Society [source]

Spatial and temporal variation in the relative contribution of density dependence, climate variation and migration to fluctuations in the size of great tit populations

Vidar Grøtan
Summary 1The aim of the present study is to model the stochastic variation in the size of five populations of great tit Parus major in the Netherlands, using a combination of individual-based demographic data and time series of population fluctuations. We will examine relative contribution of density-dependent effects, and variation in climate and winter food on local dynamics as well as on number of immigrants. 2Annual changes in population size were strongly affected by temporal variation in number of recruits produced locally as well as by the number of immigrants. The number of individuals recruited from one breeding season to the next was mainly determined by the population size in year t, the beech crop index (BCI) in year t and the temperature during March,April in year t. The number of immigrating females in year t + 1 was also explained by the number of females present in the population in year t, the BCI in autumn year t and the temperature during April,May in year t. 3By comparing predictions of the population model with the recorded number of females, the simultaneous modelling of local recruitment and immigration explained a large proportion of the annual variation in recorded population growth rates. 4Environmental stochasticity especially caused by spring temperature and BCI did in general contribute more to annual fluctuations in population size than density-dependent effects. Similar effects of climate on local recruitment and immigration also caused covariation in temporal fluctuations of immigration and local production of recruits. 5The effects of various variables in explaining fluctuations in population size were not independent, and the combined effect of the variables were generally non-additive. Thus, the effects of variables causing fluctuations in population size should not be considered separately because the total effect will be influenced by covariances among the explanatory variables. 6Our results show that fluctuations in the environment affect local recruitment as well as annual fluctuations in the number of immigrants. This effect of environment on the interchange of individuals among populations is important for predicting effects of global climate change on the pattern of population fluctuations. [source]

Variable reproductive effort for two ptarmigan species in response to spring weather in a northern alpine ecosystem

Scott Wilson
Predicting how animal populations respond to climate change requires knowledge of how species traits influence the response of individuals to variation in anuual weather. Over a four-year study with two warm and two cold years, we examined how sympatric rock ptarmigan Lagopus muta and white-tailed ptarmigan L. leucura in the southern Yukon Territory respond to spring weather in terms of breeding phenology and the allocation of reproductive effort. The onset of breeding was approximately synchronous; for each one-degree rise in spring temperature, mean breeding dates of rock and white-tailed ptarmigan advanced by about 2.7 and 4 days respectively. Although onset of breeding was similar, the two species differed in their reproductive effort. As breeding was delayed, average first clutch sizes of rock ptarmigan declined from 9.4 to 5.8 eggs over the breeding period, while those of white-tailed ptarmigan only declined from an average of 7.8 to 6.8. Rock ptarmigan were also less likely to re-nest if their first clutch was lost to predators and as a consequence they had shorter breeding seasons. White-tailed ptarmigan produced about 25% more offspring annually than rock ptarmigan and contributed more young through re-nesting. While white-tailed ptarmigan had higher annual reproductive output, adult rock ptarmigan had a 20,25% higher annual survival rate, which may indicate a reproduction,survival trade-off for the two species. These results show that even within the same location, closely related species can differ in how they allocate effort as environmental conditions fluctuate. [source]

Temporal dynamics of marginal steppic vegetation over a 26-year period of substantial environmental change

Silvia Matesanz
Abstract Questions: (1) Is climate a strong driver of vegetation dynamics, including interannual variation, in a range margin steppic community? (2) Are there long-term trends in cover and species richness in this community, and are these consistent across species groups and species within groups? (3) Can long-term trends in plant community data be related to variation in local climate over the last three decades? Location: A range margin steppic grassland community in central Germany. Methods: Cover, number and size of all individuals of all plant species present in three permanent 1-m2 plots were recorded in spring for 26 years (1980,2005). Climatic data for the study area were used to determine the best climatic predictor for each plant community, functional group and species variable (annual data and interannual variation) using best subsets regression. Results: April and autumn temperature showed the highest correlation with total cover and species richness and with interannual variations of cover and richness. However, key climate drivers differed between the five most abundant species. Similarly, total cover and number and cover of perennials significantly decreased over time, while no trend was found for the cover and number of annuals. However, within functional groups there were also contrasting species-specific responses. Long-term temperature increases and high interannual variability in both temperature and precipitation were strongly related to long-term trends and interannual variations in plant community data. Conclusions: Temporal trends in vegetation were strongly associated with temporal trends in climate at the study site, with key roles for autumn and spring temperature and precipitation. Dynamics of functional groups and species within groups and their relationships to changes in temperature and precipitation reveal complex long-term and interannual patterns that cannot be inferred from short-term studies with only one or a few individual species. Our results also highlight that responses detected at the functional group level may mask contrasting responses within functional groups. We discuss the implications of these findings for attempts to predict the future response of biodiversity to climate change. [source]

Is there a higher risk for herbivore outhreaks after cold mast years?

ECOGRAPHY, Issue 6 2000
An analysis of two plant/herbivore series from southern Norway
Historical data on two plant-herbivore interactions from southern Norway were used to test the hypothesis that the degree of herbivore outbreaks in post-mast years is negatively related to summer temperatures in the mast year, because plants are more depressed after a high seed production if temperatures and thus the photosynthetic activity is low. The plant species were the sessile oak Quercus petraea and the bilberry Vaceinium myrtillus. For the former species post-mast years were identified from reports given by the local forest authorities for the period 1930,48, and from acorn export curves for the period 1949,98, For the latter species, post-mast years were identified mainly from bilberry export curves for the period 1920,31, from game reports for the period 1932,78. and from diary notes for the period 1979,87. The herbivore species used were the green oak leaf roller moth Tortrix viridana and the capercaillie Tetrao urogallus. Eight moth outbreaks on oak forests were reported by the forest authorities in the period 1930,98, and they all started in a post-mast year of the sessile oak. There were however also eleven post-mast years without moth outbreaks. According to game reports, observations and autumn counts, all increases in the autumn population size of capercaillie during 1920 88 occurred in or after a year with high bilberry production. Among i8 post-mast years, there were seven with strong increase, seven with slight or moderate increase, and four with no increase. For both herbivore species, post-mast years with marked population increases had significantly lower summer temperatures in the preceding (mast) year than had post-mast years with no or slight increases. For moth populations there also was a negative effect of high temperatures in April, possibly because moth eggs tend to hatch too early relative lo budburst if spring temperatures are high. For the capercaillie, high amount of precipitation in June , July seemed to have some negative impact on the autumn population sizes, as also found in previous studies. [source]

Copepod life cycle adaptations and success in response to phytoplankton spring bloom phenology

Abstract In a seasonal environment, the timing of reproduction is usually scheduled to maximize the survival of offspring. Within deep water bodies, the phytoplankton spring bloom provides a short time window of high food quantity and quality for herbivores. The onset of algal bloom development, however, varies strongly from year to year due to interannual variability in meteorological conditions. Furthermore, the onset is predicted to change with global warming. Here, we use a long-term dataset to study (a) how a cyclopoid copepod, Cyclops vicinus, is dealing with the large variability in phytoplankton bloom phenology, and (b) if bloom phenology has an influence on offspring numbers. C. vicinus performed a two-phase dormancy, that is, the actual diapause of fourth copepodid stages at the lake bottom is followed by a delay in maturation, that is, a quiescence, within the fifth copepodid stage until the start of the spring bloom. This strategy seems to guarantee a high temporal match of the food requirements for successful offspring development, especially through the highly vulnerable naupliar stages, with the phytoplankton spring bloom. However, despite this match with food availability in all study years, offspring numbers, that is, offspring survival rates were higher in years with an early start of the phytoplankton bloom. In addition, the phenology of copepod development suggested that also within study years, early offspring seems to have lower mortality rates than late produced offspring. We suggest that this is due to a longer predator-free time period and/or reduced time stress for development. Hence, within the present climate variability, the copepod benefited from warmer spring temperatures resulting in an earlier phytoplankton spring bloom. Time will show if the copepod's strategy is flexible enough to cope with future warming. [source]

Climate warming and the evolution of morphotypes in a reptile

Abstract Climate warming is known to have effects on population dynamics through variations in survival, fecundity and density. However, the impacts of climate change on population composition are still poorly documented. Morphotypes are powerful markers to track changes in population composition. In the common lizard, Lacerta vivipara, individuals display two types of dorsal patterns: reticulated (R individuals) and linear (L individuals). We examined how local warming affected intrapopulation frequencies of these morphotypes across 11 years. We observed changes in morph frequency of dorsal patterns across years, paralleling the rise of spring temperatures. The proportion of R individuals increased with June temperatures in juveniles, yearlings, and adult males and females. Three mechanisms could explain these changes: phenotypic plasticity, microevolution and/or dispersal between populations. We investigated the ontogenetic determinism, fitness and recruitment rates associated with dorsal morphotypes. Dorsal pattern ontogeny showed temperature dependence but this relationship was not associated with the warming trend during this study. We found variation by morphotype in survival and clutch size, but these factors did not explain R frequency increases. Among all the parameters considered in this study, only a decrease of immigration, which was more pronounced in the L morphotype, could explain the change in population composition. To our knowledge, this provides the first evidence of the impact of climate warming on population composition due to its effects on immigration. [source]

Climatic effects on the breeding phenology and reproductive success of an arctic-nesting goose species

Abstract Climate warming is pronounced in the Arctic and migratory birds are expected to be among the most affected species. We examined the effects of local and regional climatic variations on the breeding phenology and reproductive success of greater snow geese (Chen caerulescens atlantica), a migratory species nesting in the Canadian Arctic. We used a long-term dataset based on the monitoring of 5447 nests and the measurements of 19 234 goslings over 16 years (1989,2004) on Bylot Island. About 50% of variation in the reproductive phenology of individuals was explained by spring climatic factors. High mean temperatures and, to a lesser extent, low snow cover in spring were associated with an increase in nest density and early egg-laying and hatching dates. High temperature in spring and high early summer rainfall were positively related to nesting success. These effects may result from a reduction in egg predation rate when the density of nesting geese is high and when increased water availability allows females to stay close to their nest during incubation recesses. Summer brood loss and production of young at the end of the summer increased when values of the summer Arctic Oscillation (AO) index were either very positive (low temperatures) or very negative (high temperatures), indicating that these components of the breeding success were most influenced by the regional summer climate. Gosling mass and size near fledging were reduced in years with high spring temperatures. This effect is likely due to a reduced availability of high quality food in years with early spring, either due to food depletion resulting from high brood density or a mismatch between hatching date of goslings and the timing of the peak of plant quality. Our analysis suggests that climate warming should advance the reproductive phenology of geese, but that high spring temperatures and extreme values of the summer AO index may decrease their reproductive success up to fledging. [source]

Climate warming, dispersal inhibition and extinction risk

Abstract Global warming impels species to track their shifting habitats or adapt to new conditions. Both processes are critically influenced by individual dispersal. In many animals, dispersal behaviour is plastic, but how organisms with plastic dispersal respond to climate change is basically unknown. Here, we report the analysis of interannual dispersal change from 16 years of monitoring a wild population of the common lizard, and a 12-year manipulation of lizards' diet intended to disentangle the direct effect of temperature rise on dispersal from its effects on resource availability. We show that juvenile dispersal has declined dramatically over the last 16 years, paralleling the rise of spring temperatures during embryogenesis. A mesoscale model of metapopulation dynamics predicts that in general dispersal inhibition will elevate the extinction risk of metapopulations exposed to contrasting effects of climate warming. [source]

Advanced snowmelt causes shift towards positive neighbour interactions in a subarctic tundra community

Abstract Positive and negative species interactions are important factors in structuring vegetation communities. Studies in many ecosystems have focussed on competition; however, facilitation has often been found to outweigh competition under harsh environmental conditions. The balance between positive and negative species interactions is known to shift along spatial, temporal and environmental gradients and thus is likely to be affected by climate change. Winter temperature and precipitation patterns in Interior Alaska are rapidly changing and could lead to warmer winters with a shallow, early melting snow cover in the near future. We conducted snow manipulation and neighbour removal experiments to test whether the relative importance of positive and negative species interactions differs between three winter climate scenarios in a subarctic tundra community. In plots with ambient, manually advanced or delayed snowmelt, we assessed the relative importance of neighbours for survival, phenology, growth and reproduction of two dwarf shrub species. Under ambient conditions and after delayed snowmelt, positive and negative neighbour effects were generally balanced, but when snowmelt was advanced we found overall facilitative neighbour effects on survival, phenology, growth and reproduction of Empetrum nigrum, the earlier developing of the two target species. As earlier snowmelt was correlated with colder spring temperatures and a higher number of frosts, we conclude that plants experienced harsher environmental conditions after early snowmelt and that neighbours could have played an important role in ameliorating the physical environment at the beginning of the growing season. [source]

Inter- and intraspecific differences in climatically mediated phenological change in coexisting Triturus species

Abstract Climate and weather affect phenological events in a wide range of taxa, and future changes might disrupt ecological interactions. Amphibians are particularly sensitive to climate, but few studies have addressed climatically mediated change in the phenology of closely related species or sexes. Here, we test the hypothesis that changes in spring temperatures result in phenological change among Triturus, and we examine inter- and intraspecific differences in response. Coexisting populations of Triturus helveticus and Triturus vulgaris at Llysdinam pond in mid-Wales (53°12,59,N 3°27,3,W) were monitored using pitfall traps along a drift fence during 1981,1987, and again in 1997,2005. Spring temperature over the same period explained up to 74% of between-year variability in median arrival date, with a significant advance of 2,5 days with every degree centigrade increase. Changes were greater for males than females of both species, and greater for T. helveticus than T. vulgaris within sexes, resulting in an increasing temporal separation between arrivals of male T. helveticus and all other groups. These data illustrate for the first time how climatic change might have differential effects on sympatric species and on the two sexes. [source]

The challenges of conservation for declining migrants: are reserve-based initiatives during the breeding season appropriate for the Pied Flycatcher Ficedula hypoleuca?

IBIS, Issue 3 2009
Creating conservation policies for declining migrant species in response to global change presents a considerable challenge. Migrant species are affected by factors at breeding grounds, overwintering areas and during migration. Accordingly, reserve-based management during the breeding season is not always a suitable conservation strategy. Recent Pied Flycatcher population decline typifies the pattern for many migrants. The UK population has declined by 43% in the past decade, but explanations, and possible solutions, remain elusive. We use 15 years of data (1990,2004) from a declining British population to establish possible reasons for decline, considering: (1) breeding performance (including the influences of competition and predation); (2) weather patterns caused by the winter phase (December,March) of the North Atlantic Oscillation (NAO), which modify conditions experienced at wintering grounds and on migration; and (3) possible impacts of climate change on spring temperatures. We conclude that decreasing breeding performance is contributing to decline, but that non-breeding factors are more important. Winter NAO index is a strong predictor of breeding population, probably because it influences food abundance in Africa and at migratory stopover points. Importantly, however, year itself enhances the predictive model, indicating that influences on population remain unaccounted for by current research. Management strategies based on increasing breeding productivity cannot fully address population decline because non-breeding factors appear important. However, as breeding performance is declining, breeding-based strategies remain useful conservation tools. To this end, our research indicates that optimal placement of nestboxes as regards orientation and habitat management to increase larval food supplies could increase productivity significantly. [source]

Long-term variability in precipitation and streamflow in Iceland and relations to atmospheric circulation

Jóna Finndís Jónsdóttir
Abstract How the variability of the atmospheric circulation affects precipitation in Iceland is not completely understood. Also, the sea surface temperature (SST) has a strong influence on the temperature over the country, and thereby, snow and glacial melt. This study, therefore, aims at explaining how atmospheric circulation and sea surface temperature influence seasonal and annual precipitation, and, consequently, runoff in Iceland. Empirical orthogonal function (EOF) analysis is performed on annual and seasonal time series of precipitation and discharge to identify their key modes of variability during the period 1966,2004. The correlation between the time series of each EOF mode with individual time series of sea level pressure (SLP), air temperature and SST was then evaluated. The analyses evidenced how large-scale climate variables are connected to the regional precipitation and runoff in Iceland. They showed that the strength of the polar vortex may be, at least, as important for the precipitation in some areas of Iceland as the strength of the Icelandic Low (IL). Moreover, the location of the semi-permanent IL often defines the predominant wind direction over the country and, as such, the regions of preferred precipitation. Since the watersheds act as large precipitation gauges with response patterns depending on the geology and glaciers, the variability of the annual discharge closely resembles the variability of precipitation, except for the glacial rivers. Glacial melt is highly correlated to air temperature and SST, and the spring discharge is affected by winter and spring temperatures. The results also revealed that Icelandic hydrological conditions in the spring can be forecasted by precipitation and temperature of the autumn and winter seasons, as well as by the general prevalent circulation patterns. Additionally, a potential for seasonal forecast of precipitation, and river discharge in other seasons was identified, particularly if seasonal forecast of SLP is available. Copyright © 2008 Royal Meteorological Society [source]

Air temperatures at Armagh Observatory, Northern Ireland, from 1796 to 2002

C. J. Butler
Abstract Three independent mean temperature series for Armagh Observatory, covering the period 1796,2002 have been calibrated and corrected for the time of reading and exposure. Agreement between the three series is good in regions of overlap. With a short gap in the Armagh data from 1825 to 1833 filled by data from two stations in Dublin, the resulting series is the longest for the island of Ireland and one of the longest for any single site in the British Isles. Over the past 207 years, we note that temperatures in Armagh, in all seasons, show a gradual overall trend upwards. However, there are seasonal differences: summer and spring temperatures have increased by only half as much as those in autumn and winter. This is partly due to the exceptionally cold winters and autumns experienced prior to 1820. Relative to the overall trend, warm periods occurred in Ireland, as in other parts of Europe, in the mid-19th century, in the mid-20th century and at the end of the 20th century. Relatively cool temperatures prevailed in the early 19th century, in the 1880s and in the 1970s. Thus, if the baseline against which current temperatures are compared were moved from the late 19th century to include the earlier warm period, the apparent warming at the end of the late 20th century would be correspondingly reduced. A gradual decline in the daily temperature range at Armagh since 1844 may have resulted from higher minimum temperatures associated with increased cloudiness. A 7.8 year periodicity is identified in winter and spring mean temperatures at Armagh, which is probably a consequence of the North Atlantic oscillation. Copyright © 2005 Royal Meteorological Society [source]

Resistance of perch eggs to attack by aquatic fungi

C. G. M. Paxton
In the distinctive gelatinous Perca fluviatilis egg mass, limited fungal growth by Aphanomyces and Saprolegnia spp. especially S. diclina, occurred within dead eggs but did not spread to adjacent live eggs. Perch eggs exposed to parasitic challenge by Saprolegnia parasitica, S. dieclina (type III) and S. ferax, under fluctuating temperature regimes replicating spring water temperatures, did not have significantly greater mortality than did unchallenged controls. The observations suggest that perch eggs have some anti-fungal properties which usually prevent the spread of fungus throughout the egg mass and that under normal spring temperatures there should be negligible ecological consequences of fungal infection in perch egg masses. [source]

Global warming affects phenology and voltinism of Lobesia botrana in Spain

Daniel Martín-Vertedor
1Climate change is promoting alterations of a very diverse nature in the life cycle of an array of insect species, including changes in phenology and voltinism. In Spain, there is observational evidence that the moth Lobesia botrana Den. & Schiff. (Lep.: Tortricidae), a key vine pest that is usually trivoltine in Mediterranean latitudes, tends to advance spring emergence, displaying a partial fourth additional flight, a fact that is potentially attributable to global warming. 2To verify this hypothesis, local temperatures were correlated with L. botrana phenology in six vine-growing areas of southwestern Spain during the last two decades (1984,2006) by exploiting the database of flight curves obtained with sexual pheromone traps. The dates of second and third flight peaks of the moth were calculated for each area and year and then correlated with both time (years) and local temperatures. 3The results obtained demonstrated a noteworthy trend towards local warming (as a result of global warming) in the last two decades, with mean increases in annual and spring temperatures of 0.9 and 3.0°C, respectively. Therefore, L. botrana phenology has significantly advanced by more than 12 days. Moreover, the phenological advance contributed to increased moth voltinism in 2006 by promoting a complete fourth additional flight, a fact that has never been reported previously to our knowledge in the Iberian Peninsula. 4The potential impact of an earlier phenology and increased voltinism in L. botrana is discussed from an agro-ecological perspective. [source]

Modelling trends in central England temperatures

David I. Harvey
Abstract Trends are extracted from the central England temperature (CET) data available from 1723, using both annual and seasonal averages. Attention is focused on fitting non-parametric trends and it is found that, while there is no compelling evidence of a trend increase in the CET, there have been three periods of cooling, stability, and warming, roughly associated with the beginning and the end of the Industrial Revolution. There does appear to have been an upward shift in trend spring temperatures, but forecasting of current trends is hazardous because of the statistical uncertainty surrounding them. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Seasonal synchrony of life cycles between the exotic predator, Pseudoscymnus tsugae (Coleoptera: Coccinellidae) and its prey, the hemlock woolly adelgid Adelges tsugae (Homoptera:Adelgidae)

Carole A. S. -J.
Abstract 1 The seasonal synchrony between the exotic predator, Pseudoscymnus tsugae and its prey, the hemlock woolly adelgid, Adelges tsugae, was investigated in field cages and in the forest in Connecticut, U.S.A. from 1997,1999. 2 In early spring, egg to adult development took 45 d at 18.7 °C, 39.7 d at 20.2 °C and 31.5 d at 22.7 °C. Earliest emerging F1 adults mated and oviposited in the same year. whereas F1 and F2 females emerging later in the summer mated and reserved most of their egg complement for the following year. 3 A second generation of P. tsugae is possible in Connecticut but may be delayed by cool mid-spring temperatures. Individuals of three generations of P. tsugae, including overwintering survivors, may coexist in July and August and adults can be found year-round with A. tsugae in infested hemlock forests. 4 A linear regression model for development from egg to adult under field temperatures gave good agreement with results from constant temperature findings. The model predicted a lower development threshold of 9.5 °C and a sum of effective temperatures of 405 day °C. Development time of P. tsugae is shorter relative to its prey A. tsugae and generation time ratios of predator to prey was 0.16,0.5, with an advantage conferred on the coccinellid. 5 Overwintering ability and behaviour were determined in 1998,1999 and adults remained on infested hemlock branches throughout a mild winter, becoming reproductively active in mid-April. Peak oviposition period extended from April to July, in synchrony with peak oviposition and developing stages of two generations of A. tsugae. [source]

Recruitment of Heliozoa, rhizopods and rotifers from the sediments of an extremely acidic lake during spring and early summer

Elanor M. Bell
Abstract The goal of this study was to investigate the recruitment of zooplankton from the littoral sediment of Lake 111, an acidic lake in north-east Germany, in April (spring) and June (early summer), and its role in coupling the benthos and the pelagic. Maximum heliozoan and rhizopod recruitment occurred in early summer from sediment cores incubated at ambient water temperatures (20°C). Conversely, recruitment of the rotifer Cephalodella sp. was highest in spring at ambient spring temperatures of 12°C. A combination of passive and active recruitment processes is likely responsible. The seasonal abiotic and biotic sediment characteristics were relatively constant and therefore not likely responsible for the observed temporal recruitment pattern. The sediment water and carbon content ranged from 20 to 50% (mean = 29 ± 6% standard deviation) and 2,12% (mean = 5 ± 2% standard deviation), respectively. Similarly, there was little variation in the chlorophyll- a (mean = 0.2 ± 0.2 µg Chl- a g,1 dry weight , 6.1 ± 3.9 mg Chl- a m,2). The in situ sediment bacterial density (0.82 × 109 ± 0.26 × 109 g,1 dry weight , 1.01 × 109 ± 0.34 × 109 cells cm,3) was high. In contrast, the abundance of zoobenthos and their resting stages was low (< 25 individuals cm,3, and mean of 90 ± 75 cysts cm,3, respectively), with no temporal pattern being observed. Temperature was the only abiotic factor influencing recruitment. This study suggests that, even in relatively young, chemically extreme lakes, the benthos can play an important role in whole lake microbial processes and zooplankton community composition. Such benthic repositories of resting stages potentially provide protection against adverse environmental changes. [source]