			Home About us Contact

July Temperature (july + temperature)

Distribution by Scientific Domains

Life Sciences	44%
Earth and Environmental Science	44%

Kinds of July Temperature

mean july temperature

Selected Abstracts

Patterns of ant species richness along elevational gradients in an arid ecosystem

GLOBAL ECOLOGY, Issue 2 2003
Nathan J. Sanders
ABSTRACT Aim In this study, we examine patterns of local and regional ant species richness along three elevational gradients in an arid ecosystem. In addition, we test the hypothesis that changes in ant species richness with elevation are related to elevation-dependent changes in climate and available area. Location Spring Mountains, Nevada, U.S.A. Methods We used pitfall traps placed at each 100-m elevational band in three canyons in the Spring Mountains. We compiled climate data from 68 nearby weather stations. We used multiple regression analysis to examine the effects of annual precipitation, average July precipitation, and maximum and minimum July temperature on ant species richness at each elevational band. Results We found that patterns of local ant species richness differed among the three gradients we sampled. Ant species richness increased linearly with elevation along two transects and peaked at mid-elevation along a third transect. This suggests that patterns of species richness based on data from single transects may not generalize to larger spatial scales. Cluster analysis of community similarity revealed a high-elevation species assemblage largely distinct from that of lower elevations. Major changes in the identity of ant species present along elevational gradients tended to coincide with changes in the dominant vegetation. Regional species richness, defined here as the total number of unique species within an elevational band in all three gradients combined, tended to increase with increasing elevation. Available area decreased with increasing elevation. Area was therefore correlated negatively with ant species richness and did not explain elevational patterns of ant species richness in the Spring Mountains. Mean July maximum and minimum temperature, July precipitation and annual precipitation combined to explain 80% of the variation in ant species richness. Main conclusions Our results suggest that in arid ecosystems, species richness for some taxa may be highest at high elevations, where lower temperatures and higher precipitation may support higher levels of primary production and cause lower levels of physiological stress. [source]

Vegetation gradients in Atlantic Europe: the use of existing phytosociological data in preliminary investigations on the potential effects of climate change on British vegetation

GLOBAL ECOLOGY, Issue 3 2000
J. 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]

The health of Arctic populations: Does cold matter?

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010
T. Kue Young
The objective of the study was to examine whether cold climate is associated with poorer health in diverse Arctic populations. With climate change increasingly affecting the Arctic, the association between climate and population health status is of public health significance. The mean January and July temperatures were determined for 27 Arctic regions based on weather station data for the period 1961,1990 and their association with a variety of health outcomes assessed by correlation and multiple linear regression analyses. Mean January temperature was inversely associated with infant and perinatal mortality rate, age-standardized mortality rate from respiratory diseases, and age-specific fertility rate for teens and directly associated with life expectancy at birth in both males and females, independent of a variety of socioeconomic, demographic, and health care factors. Mean July temperature was also associated with infant mortality and mortality from respiratory diseases, and with total fertility rate. For every 10°C increase in mean January temperature, the life expectancy at birth among males increased by about 6 years and infant mortality rate decreased by about 4 deaths/1,000 livebirths. Cold climate is significantly associated with higher mortality and fertility in Arctic populations and should be recognized in public health planning. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source]

Developing a modern pollen,climate calibration data set for Norway

BOREAS, Issue 4 2010
ANNE E. BJUNE
Bjune, A. E., Birks, H. J. B., Peglar, S. M. & Odland, A. 2010: Developing a modern pollen,climate calibration data set for Norway. Boreas, Vol. 39, pp. 674,688. 10.1111/j.1502-3885.2010.00158.x. ISSN 0300-9483. Modern pollen,climate data sets consisting of modern pollen assemblages and modern climate data (mean July temperature and mean annual precipitation) have been developed for Norway based on 191 lakes and 321 lakes. The original 191-lake data set was designed to optimize the distribution of the lakes sampled along the mean July temperature gradient, thereby fulfilling one of the most critical assumptions of weighted-averaging regression and calibration and its relative, weighted-averaging partial least-squares regression. A further 130 surface samples of comparable taphonomy, taxonomic detail and analyst became available as a result of other projects. These 130 samples, all from new lakes, were added to the 191-lake data set to create the 321-lake data set. The collection and construction of these data sets are outlined. Numerical analyses involving generalized linear modelling, constrained ordination techniques, weighted-averaging partial least-squares regression, and two different cross-validation procedures are used to asses the effects of increasing the size of the calibration data set from 191 to 321 lakes. The two data sets are used to reconstruct mean July temperature and mean annual precipitation for a Holocene site in northwest Norway and a Lateglacial site in west-central Norway. Overall, little is to be gained by increasing the modern data set beyond about 200 lakes in terms of modern model performance statistics, but the down-core reconstructions show less between-sample variability and are thus potentially more plausible and realistic when based on the 321-lake data set. [source]

Holocene vegetation and climate history on a continental-oceanic transect in northern Fennoscandia based on pollen and plant macrofossils

BOREAS, Issue 3 2004
ANNE E. BJUNE
Changes in tree-line, mean July temperature (Tjul) and mean annual precipitation (Pann) for the last 10200 cal. yr BP are reconstructed on the basis of pollen and plant macrofossils preserved in lake sediments from two sites near the present-day tree-line in Troms, northern Norway. Quantitative climate reconstructions are performed using pollen-climate transfer functions based on WA-PLS regression. Early Holocene Betula pubescens forests were gradually replaced by Pinus sylvestris at Dalmutladdo (355 m a.s.l.) starting about 7000 cal. yr BP. The local presence of pine woodland at that time is supported by finds of stomata and plant macrofossils and by high pollen accumulation rates. Until about 4000 cal. yr BP the P. sylvestris tree-line was 250,300 m higher than today, suggesting Tjul about 2.0C higher than at present. The later part of the Holocene has a cooler and moister climate and an increasing development of mires and fern-rich vegetation, as shown by increases of Sphagnum and fern spores and the re-establishment of B. pubescens woodland. The reconstructed Tjul from the two sites shows similar trends to previously published data, with Tjul1,2C warmer between 9500 cal. yr BP and 2000 cal. yr BP Tjul. Maximum Tjul values occur between 8500 and 4500 cal. yr BP, after which there is a gradual decrease in Tjul. [source]

Palaeoenvironmental context of the Late-glacial woolly mammoth (Mammuthus primigenius) discoveries at Condover, Shropshire, UK

GEOLOGICAL JOURNAL, Issue 4 2009
J. R. M. Allen
Abstract In 1986/1987 the remains of several mammoths, Mammuthus primigenius (Blumenbach), were discovered on the spoil heap of an actively working gravel pit at Condover, Shropshire, England. The discovery of the remains posed two questions that could be addressed by analyses of biological proxies. First, as none of the bones was found in situ it was necessary to confirm the stratum in which the remains occurred. Second, what was the environment in which these animals lived and died? A range of biological indicators was used to address these questions, including pollen, spore and algal, plant macrofossil, invertebrate, anuran and biological mineral analyses. Multivariate statistical analyses of palynological and Pediastrum data, along with evidence from the Coleopteran assemblages, support the attribution of the mammoth bones to a unit of dark grey clayey sandy silt, although they may have lived at the time of the overlying green detritus mud. The palaeobiological data supports the correlation of these sediments to the Devensian Late-glacial. The mammoths entered this basin at the start of the Late-glacial Interstadial (Greenland Interstadial 1e) (ca. 14,830,3930 cal. year BP; 12,300,±,110 14C year BP) and became mired in soft cohesive sediments. Palaeotemperature reconstructions, based on the Coleopteran assemblages, from the time when the mammoths actually became mired, show that the climate was temperate with mean July temperatures between 15 and 19°C and mean January temperatures between ,13 and +6°C. Biological indicators from the sediments encasing the mammoths indicate that the landscape surrounding the basin was treeless and dry, contrasting with rich vegetation within the basin itself that had possibly attracted the mammoths to the site. Evidence of sedimentary disturbance suggests that the mammoths caused large-scale bioturbation of the deposits making palaeoenvironmental interpretations difficult. Fossils of terrestrial blowflies, carcass and dung beetles show that some of the decaying corpses must have lain exposed on the land surface for sufficient time for the soft parts to have rotted away and skin and bones to have become desiccated before many of them sank into the dark grey clayey sandy silt. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Post-Hypsithermal plant disjunctions in western Alberta, Canada

JOURNAL OF BIOGEOGRAPHY, Issue 3 2003
W. L Strong
Abstract Aim, Evaluate the hypothesis that nine disjunct vascular plant species along the eastern slopes of the Rocky Mountains and in the Peace River District of west-central Alberta represent remnants of more southerly vegetation that occupied these areas during the Holocene Hypsithermal (9000,6000 yr bp). Alternatively, these plants represent populations that became established because of independent chance dispersal events. Location, This study focuses on the area east of the Rocky Mountain Continental Divide in the Province of Alberta and the State of Montana in western Canada and USA, respectively. Methods, Disjunct species were identified and their distributions mapped based on a review of occurrence maps and records, botanical floras and checklists, herbaria specimens, ecological and botanical studies, and field surveys of selected species. A disjunct species was defined as a plant population separated from its next nearest occurrence by a distance of > 300 km. Evaluation of the hypothesis was based on a review of published and unpublished pollen stratigraphy and palaeoecological studies. The potential geographical distribution of Hypsithermal vegetation was based on modern regional-based ecosystem mapping and associated monthly temperature summaries as well as future climatic warming models. Results, The hypothesis was compatible with Holocene pollen stratigraphy, Hypsithermal permafrost and fen occurrence, and palaeosol phytolith analyses; and future global climatic warming models. Modelled regional Hypsithermal vegetation based on a 1 °C increase in July temperatures relative to current conditions, indicated that much of the boreal forest zone in Alberta could have been grassland, which would explain the occurrence of Prairie species in the Peace River District. This amount of latitudinal vegetation shift (6.5°) was similar to an earlier Hypsithermal permafrost zone location study. An equivalent shift in vegetation along the eastern Cordillera would have placed south-western Montana-like vegetation and species such as Boykinia heucheriformis (Rydb.) Rosend. and Saxifraga odontoloma Piper within the northern half of the Rocky Mountains and foothills in Alberta, which represents the location of modern-day disjunct populations of these species. Main conclusions, Warmer and drier climatic conditions during the Holocene Hypsithermal resulted in the northward displacement of vegetation zones relative to their current distribution patterns. Most of Alberta was probably dominated by grasslands during this period, except the Rocky Mountains and northern highlands. Modern-day species disjunctions within the Rocky Mountains and Peace River District as well as more northerly areas such as the Yukon Territory occurred when the vegetation receded southward in response to climatic cooling after the Hypsithermal. Wind dispersal was considered an unlikely possibility to explain the occurrence of the disjunct species, as most of the plants lack morphological adaptations for long distance transport and the prevailing winds were from west to east rather than south to north. However, consumption and transport of seeds by northward migrating birds could not be excluded as a possibility. [source]

The health of Arctic populations: Does cold matter?

Coleoptera from the Late Weichselian deposits at Nørre Lyngby, Denmark and their bearing on palaeoecology, biogeography and palaeoclimate

BOREAS, Issue 1 2000
GEOFFREY RUSSELL COOPE
The freshwater sediments exposed on the cliffs at Nørre Lyngby northern Jutland has long been a classical locality for the study of Danish Quaternary geology, palaeontology and archaeology. These deposits date from the latter part of the Allerød period (i.e. G I-1). Samples for insect analysis have been taken from both the northern and southern exposures of these deposits. Ninety-five- taxa of Coleoptera (beetles) were obtained, of which 69 could be named to species. Of the latter, 23 are not found living in Denmark today. Most of these are still living in northern Fennoscandia but one species is now confined to Mongolia. These assemblages have enabled a detailed picture of the local environment to be reconstructed, showing that the basin-like profile of the deposits represents a section through a channel with slowly moving water. It has been possible to quantify the thermal climate of the time using the Mutual Climatic Range method indicating that mean July temperatures were about 10°C and mean January temperatures were about , 12°C. These figures are considered in the context of Lateglacial climatic reconstructions obtained from coleopteran assemblages elsewhere in northwestern Europe. [source]