Summer Temperature Conditions Research Articles

A Holocene North Atlantic SST record and regional climate variability

By combined use of 210Pb dates, identification of Icelandic tephras of known age, and wiggle matching of 14C radiocarbon dates, exceptional accurate chronologies have been established for two cores (P1003MC and SC) raised from the same location on the Norwegian continental margin and that span the last 8 ka. They are located directly under the core of the eastern branch of Atlantic water entering the Nordic Seas. Comparing oxygen isotope measurements on the planktonic foraminiferal species Neogloboquadrina pachyderma (dex) with nearby instrumental time series, suggest that this parameter at this site primarily reflects summer temperature conditions of near surface (c. 50 m) waters. We argue that this proxy, to some degree, reflects North Atlantic sea surface temperature variability through the Holocene. A detailed correlations of the oxygen isotope record with solar proxies for the last 1 ka was not apparent for the whole 8 ka record. However, a statistically significant (>95%) spectral peak at c. 83 yr may represent the so-called Gleissberg solar cycle. A relative high correlation ( r = 0.53) between 14C productivity and the ocean near surface temperature proxy was obtained on 800–1500 year band filtered data, the latter lagging 180 year after the solar proxy. Multi-channel Singular-Spectrum Analyses carried out on the P1003 time series, the oxygen isotope record from the Renland Ice Core from Eastern Greenland, and on the Torneträsk tree-ring record from central Scandinavia, reveals a significant common frequency at 280 year. The expression of this frequency in the different records shows variability in phase relationship and strength over time and does not appear to have any similarity to any known modes of climate variability in the area. In order to predict future climate change in the region it is of utmost importance to develop a better understanding of the mechanisms behind multi-decadal and multi-centennial scale climate variability.

Thermal Stress Performance Analysis for a New External Wall Insulation System

In this paper, two models are taken as subjects, one being a small frame exterior composite insulation system with the shear key, the other being the system without the shear key. In extreme high temperature conditions in summer, the small frame exterior composite insulation system temperature stress and strain are analyzed with numerical simulation using finite element method. Results show that shear key can effectively reduce the stress concentration, weaken the stress peak by nearly 50% and reduce the deformation by nearly 50% as well, thus effectively reducing the probability of crack cracking, improving the durability and extending service life.

Present and forecasted xeric climatic limits of beech and sessile oak distribution at low altitudes in Central Europe

Xeric (trailing) forest range limits are particularly vulnerable to impacts of predicted climate change. Regional modelling studies contribute to the identification of potential local climatic threats and may support appropriate management strategies. We carried out bioclimatic distribution modelling of two climate-dependent, dominant tree species, beech and sessile oak, to determine the most influential climatic variables limiting their distributions and to predict their climate-induced range shifts over the twenty-first century in the forest-steppe biome transition zone of Hungary. To exclude confounding effects of edaphic conditions, only data of zonal sites were evaluated. For both species, temperature and precipitation conditions in late spring and summer appear as principal variables determining the distribution, with beech particularly affected by summer drought. Projections from the applied fine-scale analysis and modelling results indicate that climate change may lead to drastic reduction in macroclimatically suitable sites for both forest types. Regarding the stands in zonal position, 56–99% of present-day beech forests and 82–100% of sessile oak forests might be outside their present bioclimatic niche by 2050. Phenotypic plasticity, longevity, endurance of non-zonal stands and prudent human support may brighten these dire predictions. Nevertheless, an urgent adjustment of forest management and conservation strategies seems inevitable.

Core-top calibration of δ18O and δ13C of G. ruber (white) and U. mediterranea along the southern Adriatic coast of Italy

We carried out an extensive survey of the oxygen and carbon isotope composition of the planktic species G. ruber (white) and of the benthic species U. mediterranea along the southern Italian coast of the Adriatic Sea and in the Gulf of Taranto. Comparison with seasonal satellite-based sea surface temperature maps and water column profiles as well as with several sets of water samples allows estimation of the effect of salinity and different nutrient supply on the δ18O and δ13C of foraminifera. The results indicate that G. ruber (white), while being highly affected by different salinity and nutrient distributions related to circulation patterns of major water masses, dominantly record summer temperature conditions. U. mediterranea reflect the recent environmental conditions, such as nutrient supply and bottom water temperature characteristics, along the southern Italian coast and clearly show the transition from a near-coastal eutrophic system to an offshore oligotrophic system.

Sexual Plasticity and Self-Fertilization in the Sea Anemone Aiptasia diaphana

Traits that influence reproductive success and contribute to reproductive isolation in animal and plant populations are a central focus of evolutionary biology. In the present study we used an experimental approach to demonstrate the occurrence of environmental effects on sexual and asexual reproduction, and provide evidence for sexual plasticity and inter-clonal fertilization in laboratory-cultured lines of the sea anemone Aiptasia diaphana. We showed that in A. diaphana, both asexual reproduction by pedal laceration, and sexual reproduction have seasonal components. The rate of pedal laceration was ten-fold higher under summer photoperiod and water temperature conditions than under winter conditions. The onset of gametogenesis coincided with the rising water temperatures occurring in spring, and spawning occurred under parameters that emulated summer photoperiod and temperature conditions. In addition, we showed that under laboratory conditions, asexually produced clones derived from a single founder individual exhibit sexual plasticity, resulting in the development of both male and female individuals. Moreover, a single female founder produced not only males and females but also hermaphrodite individuals. We further demonstrated that A. diaphana can fertilize within and between clone lines, producing swimming planula larvae. These diverse reproductive strategies may explain the species success as invader of artificial marine substrates. We suggest that these diverse reproductive strategies, together with their unique evolutionary position, make Aiptasia diaphana an excellent model for studying the evolution of sex.

Feeding rates in the sailfin molly Poecilia latipinna and its coexisting sexual parasite, the gynogenetic Amazon molly Poecilia formosa

Feeding rates of the gynogenetic Amazon molly Poecilia formosa and one of its sexual hosts, the sailfin molly Poecilia latipinna, were measured under winter and summer temperature conditions. Food consumption of the unisexual P. formosa in winter conditions was significantly higher than that of P. latipinna, and it is hypothesized that the resulting food stress might have an important influence on the population composition of these closely related fishes via higher winter mortality in P. formosa.

Application of Advanced Very High Resolution Radiometer (AVHRR)-based Vegetation Health Indices for Estimation of Malaria Cases

Satellite data may be used to map climatic conditions conducive to malaria outbreaks, assisting in the targeting of public health interventions to mitigate the worldwide increase in incidence of the mosquito-transmitted disease. This work analyzes correlation between malaria cases and vegetation health (VH) indices derived from satellite remote sensing for each week over a period of 14 years for Bandarban, Bangladesh. Correlation analysis showed that years with a high summer temperature condition index (TCI) tended to be those with high malaria incidence. Principal components regression was performed on patterns of weekly TCI during each of the two annual malaria seasons to construct a model as a function of the TCI. These models reduced the malaria estimation error variance by 57% if first-peak (June-July) TCI was used as the estimator and 74% if second-peak (August-September) was used, compared with an estimation of average number of malaria cases for each year.

Growth‐ring variations of dwarf shrubs reflect regional climate signals in alpine environments rather than topoclimatic differences

AbstractAim Our main aim is to determine if ring‐width variations in Empetrum hermaphroditum reflect regional or local topoclimate signals in an alpine environment. In the case that topoclimate provides the dominant signal, a secondary aim is to link these to spatial distribution patterns of different vegetation types.Location The study area is situated in the middle alpine belt in the Vågåmo region, Central Norwegian Scandes. Sampling sites cover different topoclimates: ridges, north‐facing slopes and south‐facing slopes.Methods We constructed ring‐width chronologies of E. hermaphroditum for each type of microsite for the common period 1951–2004. Climate data were prepared on an hourly, daily and growing‐season time scale. Climate–growth relationships were evaluated using bivariate correlations and regression tree methods for continuous time‐series analyses. In addition, extreme growth anomalies (pointer years) were compared with the climate conditions in those years. The impact of water supply on wood anatomy was determined by correlating the conductive area (percentage of vessel per growth ring) with a running mean (sum) of 10‐day intervals for temperature and precipitation.Results This study indicates that mean summer (June–August) temperatures determine the width of the growth rings of E. hermaphroditum irrespective of topoclimate. The length of the growing season, which is the most differentiating climatic factor between microsites, does not substantially alter the anatomical ring structure. Microsite differences in mean growth rates are attributed to the higher frequency of warm days. Extremely warm days limit ring‐width development at south‐facing slopes, while plants at ridges and north‐facing slopes still benefit from higher temperatures. As a consequence, pointer years are not developed synchronously at all microsites. Vessel formation is affected by available moisture, especially in the later part of the growing season.Main conclusions Topoclimate induces slight modifications of annual growth‐ring increments of E. hermaphroditum at different microsites. In contrast to the distribution patterns of vegetation types that are determined by snow cover, growth‐ring variations are related to summer temperature conditions, and the prominent regional climate signal is still reflected at all microsites. This offers the opportunity to reconstruct climatic change in alpine regions from dwarf shrub ring‐width chronologies.

Holocene and Lateglacial summer temperature reconstruction in the Swiss Alps based on fossil assemblages of aquatic organisms: a review

The taxonomic composition of chironomid, cladoceran and diatom assemblages in small lakes in the Alpine region shows a strong relationship with summer temperature. Since fossils of all three organism groups preserve well and remain identifiable in lake sediments, summer temperature transfer-functions can be developed based on the modern distribution of these organisms and applied to fossil records to reconstruct past summer temperature variability. We provide a summary of the chironomid-, cladoceran- and diatom-based transfer functions available from the Swiss Alps and discuss the potential problem of co-variation between summer temperature and lake nutrient conditions for transfer-function development. Whereas the diatom-based summer temperature transfer function remains to be evaluated in down-core reconstructions, the cladoceran- and chironomid-based transfer functions have been used successfully to produce summer temperature records on Lateglacial and Holocene time scales that are in good agreement with other temperature reconstructions in the Alps. Major problems that can be encountered when using fossil assemblages of aquatic organisms for temperature reconstruction in the Alpine region are biases in the inferred temperatures associated with human impact on lakes and parameters other than temperature affecting the fossil assemblages. A multi-proxy approach to palaeoenvironmental reconstruction is recommended to keep a close control on past catchment and within-lake processes during the time interval of interest.

Effect of Climatic Changes on Radial Increment and Age Structure Formation in High-Mountain Larch Forests of the Kuznetsk Ala Tau

The relationship between growth indices and renewal rates of the Siberian larch (Larix sibiricaLedeb.) stands that have grown at the timberline in the Kuznetsk Ala Tau mountains during the past 350 years was analyzed. The age generations of larch were formed in the 1640s, 1660s, 1680s, 1700s, 1720s, 1740s, 1760s–1770s, 1800s–1810s, 1850s, 1870s–1880s, 1900s, 1920s, and 1930s–1940s. It was shown that the formation of these age generations coincided with 10- to 30-year periods of increased growth of larch and improved temperature conditions in summer.

温熱的生理心理反応の個人差に関する研究 : 夏期における設定気温条件の場合

The study aims to investigate the individual difference of thermal physiological and psychological responses to various air temperature conditions in summer. Healthy 29 women were exposed to air temperature (20℃, 24℃, 28℃ and 32℃) during 120 minutes in a climate chamber. The results were as follows; There were differences among individuals in skin temperature, especially peripheral parts of the body, thermal comfort and thermal sensation. The subjects grouped into three based on preferred air temperature to investigate the responses in detail. Consequently, differences among three groups were found in thermal sensation, skin temperature distribution and skin temperature v.s. thermal comfort.

気温と湿度の組み合わせ条件が人体の生理・心理反応の季節差に及ぼす影響に関する試行実験

The objective of this paper is to clarify the physiological and psychological response of the human body at various air temperature and humidity conditions in summer and winter. Experiment were conducted using 2 Japanese young males under 15 kinds of the following combined conditions :air temperature of 24℃,28℃ and 32℃ and relative humidity of 50%,60%,70%,80% and 90% under still air in which the mean radiant temperature was nearly equal to air temperature. The following results were obtained : 1) Seasonal differences of the relationship between mean skin temperature and thermal sensation vote (TSV) were suggested. Neutral TSV is represented in MST of 33.8℃ in summer and of 33.6℃ in winter. 2) Seasonal differences of the relationship between humid operative temperature(HOT) and TSV were represented. Neutral TSV is represented in HOT of 24.9℃ in summer and of 25.7℃ in winter. 3)Seasonal differences of metabolism and evaporative heat loss were found.

SEM Observations on the Root Hairs of Trifoliate Orange Grafted with Satsuma Mandarin under Low Soil Moisture and High Summer Temperature Condition

SEM Observations on the Root Hairs of Trifoliate Orange Grafted with Satsuma Mandarin under Low Soil Moisture and High Summer Temperature Condition

Behaviors of volatile inorganic components in urban aerosols

A multicomponent gas–aerosol equilibrium model (Kim et al., 1993a,b; Kim and Seinfeld, 1995) was used to explain the behaviors of water content and other volatile species in the aerosols observed in polluted air mass in Central Japan. It was found that gas–aerosol equilibrium was attained after long-range transport of polluted air mass (e.g., 50 km) from emission source area, while it was not completed in large emission source areas. The present model predicted with high accuracy the gas–aerosol equilibrium of ammonium, nitrate and chloride at remote sites. The correlation coefficient was R=0.98 for ammonia and more than R=0.86 for gaseous nitric acid. It was R=0.94 for gaseous hydrochloric acid, which meant significant chlorine deficit under high-temperature and low humidity conditions was also predicted accurately. The predicted water content was consistent with that calculated by the semi-theoretical Winkler's formula (Aerosol Sceince, 13, 1973, 373–387). At RH=90% the water content attained almost the same weight as that of dry aerosol, while at about RH=60% it was less than 10%. In contrast, temperature dependency of the water content was weak except for very high air temperature conditions in summer. Finally, it emphasized the superiority of the multicomponent approach for gas–aerosol equilibrium, compared with the binary-component approach.

329 Rubus Plant Growth and Development as Influenced by Two High Summer Heat Environments

Seven Rubus cultivars were evaluated at two locations in Arkansas, northwest (Fayetteville) and southwest (Hope), to evaluate plant growth differences under high and very high summer temperature conditions. Temperatures during the hottest month (July) averaged 34 °C and 38 °C for Fayetteville and Hope, respectively. Growth; leaf area and number; and fresh and dry weights of leaves, stems, and roots were measured on the containerized raspberry cultivars Autumn Bliss, Dormanred, Heritage, Nova, Reveille, and Southland and the blackberry cultivar Arapaho. Growth measurements included number of canes per plant, number of laterals per cane, cane length, node number, and internode length. Measurements were taken monthly from June through September. Leaf areas were done after all growth measurements were taken at both locations in September. Variation occurred among cultivars and locations for leaf area, fresh and dry weights, growth, and leaf number. Plant death occurred at the Hope location, with `Heritag', `Reveille', and `Southland' all having plant mortality, while `Dormanred' and `Arapaho', both southern-adapted cultivars, had the greatest fresh and dry weights. The Fayetteville location had no plant loss after initial emergence in spring, and this more moderate environment probably contributed to higher plant survival. Our data indicated that only `Dormanred' and `Arapaho' achieved adequate survival and growth in the very high temperatures of the Hope location, whereas other cultivars (Reveille and Southland) with some southern U.S.-adapted germplasm, showed poor adaptation to the environments of our study. Our findings reflect the impact of high heat on non-adapted germplasm and reveal information on adaptation levels needed for parental consideration in breeding for southern conditions.

A laboratory assessment of the survival and vertical movement of two epibenthic gastropod species, Hydrobia ulvae (Pennant) and Littorina littorea (Linnaeus), after burial in sediment

Physical disturbance may result in the burial of the epibenthic fauna in sediment. The patches thus created undergo a `recovery' which may include the buried fauna migrating through the sediment to regain their original position in the sediment. A series of laboratory experiments were carried out to investigate the effects of prolonged burial on two epibenthic gastropod species, Hydrobia ulvae and Littorina littorea, under various sediment temperature regimes. Their ability to regain the sediment surface under simulated winter (i.e. 7.5°C) and summer (i.e. 20.3°C) temperature conditions was studied in relation to the depth and the duration of burial. The effects of sediment silt and water content was also examined in a separate experiment. The proportion of H. ulvae surviving burial in natural sediment to 5 cm depth decreased with increasing duration of burial and sediment temperature. Burial to 5 cm was fatal to L. littorea within 24 h at all the temperatures examined. In sediment mixtures which had, by dint of large interstitial spaces, a good supply of oxygen or which were very fluid (i.e. `high silt-high water' sediment) a large proportion of H. ulvae and L. littorea regained the surface within 1 day of burial. No individuals of either species regained the surface in sediment mixtures with high silt and low water contents, this included the unaltered natural sediment treatment. In all cases, the depth of burial significantly reduced the surface regaining ability of L. littorea while it had no effect on H. ulvae. The survival and the escape behaviour of buried H. ulvae and L. littorea is discussed in relation to their respiratory metabolism and the oxygen stress in the sediment. The potential contribution of the buried fauna to the recovery of soft-bottom patches is assessed.

Biotransformation of nonylphenol polyethoxylate surfactants by estuarine mixed bacterial cultures

Biotransformation of nonylphenol polyethoxylates (NPnEOs), a major class of non-ionic surfactants, was studied under laboratory conditions by using a static die-away method. The experiments were performed with autochthonous bacterial cultures that originated from two essentially different estuarine compartments, i.e., from the brackish water and saline water layers of the highly stratified Krka River estuary, Croatia. Highly specific HPLC methods were applied to study biotransformation kinetics of individual NPnEO oligomers in the range of 1–16 EO units. Mixed bacterial cultures from the brackish water layer exhibited a significantly greater ability to transform NPnEO than that from the saline water layer. The results suggest, however, that this difference should not be interpreted as a salinity effect, but rather as a consequence of a better preadaptation of the brackish water bacteria to NPnEOs in their natural habitat. The biodegradation rates, calculated by presuming first-order kinetics, showed a strong temperature dependence. The estimated overall half-lives of NPnEOs under winter temperature conditions (13°C) ranged from 23–69 days, while the half-lives determined under summer temperature conditions (22.5°C) ranged from 2.5–35 days. Transformation kinetics of larger, more hydrophilic, oligomers of NPnEOs was faster than that of the lower ones. In fact, the elimination of higher NPnEOs was followed by a significant formation of the short-chain NPnEOs (nEO = 1–4). The main lipophilic intermediate formed during the experiments was nonylphenol diethoxylate (NP2EO), whose concentration in the medium increased by a factor of 10–20. Its relatively fast accumulation was followed by a rather slow degradation. Consequently, residual concentrations of NP2EO were detected in the medium even after 30 days.

Ultrastructural Changes of the Mature Embryo Sac in Buckwheat (Fagopyrum esculentum) as a Result of High Temperature Exposure.

The ultrastructure of the mature embryo sac of common buckwheat (Fagopyrum esculentum) was studied under normal and high temperature conditions with transmission electron microscopy. The mature embryo sac consisted of a central cell and an egg apparatus that included an egg cell and two synergids. The cytoplasm of the egg apparatus is distributed characteristically in polar side. The fused nucleus of the central cell is located near the egg apparatus. The cytoplasm of the egg and central cell contained abundant mitochondria, ribosomes, plastids and rough endoplasmic reticulum (rER). In the cytoplasm of the synergids there were massive strands of parallel rER, dictyosomes and vesicles derived from dictyosomes and rER. When exposed to high temperature conditions in summer, the egg apparatus shows various features of degeneration, i.e. the accumulation of osmiophilic deposits in egg cells and synergids, collapsed synergids, incomplete membrane systems and enlarged rER in egg cells. These degeneration phenomena cause functional alterations that disrupt normal fertilization.

Reproductive success of Bursaphelenchus xylophilus and B. mucronatus under Finnish summer temperature conditions

AbstractThe objectives of this study were to determine the reproductive potential and the time required for completion of the life cycle of Bursaphelenchus xylophilus under Finnish summer temperature conditions. The reproductive success of B. xylophilus was compared with the potential of a Finnish isolate of B. mucronatus. The latter appeared more successful in reproduction particularly when cultured on Finns syhestris wood.

SEEDLING GROWTH AND SURVIVAL OF RED AND WHITE FIR IN A SIERRA NEVADA ECOTONE

We hypothesized that differential seedling establishment was responsible for the transition from white fir‐ to red fir‐dominated forest. Nearly 2,000 seeds of each species were sown within six fenced gardens that spanned the ecotone (1,902–2,073 m). Germination and seedling mortality were monitored through the first growing season. Red fir germination percentage exceeded that of white fir in all gardens in sites dominated by red fir saplings and overstory trees, and a similar pattern was true for white fir. Survival at the end of the first growing season was low and statistically similar for both species, as was the average length of life for seedlings and the causes of mortality. Relative demographic performances (an integrated measure of germination and survivorship over time) suggest that: 1) open/xeric microhabitats within the ecotone favor white fir over red fir; 2) both open/mesic and shaded/xeric microhabitats favor red fir over white fir; and 3) shaded/mesic microhabitats are equally favorable for both species. Seedlings of red and white fir were grown for 6 mo in a growth chamber that imitated early summer temperature and soil moisture conditions. Red fir seedlings were consistently heavier than white fir seedlings, in part a result of the 2.5 × greater caloric content of red fir seed. Relative growth rates were similar for both. Allocation of photosynthate to roots was greater for red fir than white fir, a result contrary to the expected pattern, given that white fir occurs at more xeric, lower elevations than red fir. No consistent differences between the species occurred in root growth or morphology.