Winter Temperature Conditions Research Articles

Tree line population monitoring of Pinus sylvestris in the Swedish Scandes, 1973–2005: implications for tree line theory and climate change ecology

Summary Demographic trends of Pinus sylvestris L. (Scots pine) tree line populations are reported for a 32‐year monitoring period (1973–2005). Functional and projective aspects of tree line performance were analysed by relating temporal variability and change of vital population parameters, such as natality/mortality, vigour, injuries, height growth and seed viability to contemporary variations in air and soil temperatures. The size of the entire sampled population increased by 50% during the 32‐year observation period and thereby pine has become a more prominent element on the landscape. This reverses a natural multicentennial or even millennial trend of tree line decline and recession. Contrasting population trends were recorded for the subperiods 1973–87 and 1988–2005, viz. decline and increase, respectively. Mean summer temperatures (JJA) did not change perceivably over and between these intervals, although some exceptionally warm summers from 1997 onwards have contributed to population expansion by increased seed viability and seedling emergence. Winter temperatures (DJF) decreased significantly over the first subperiod and were consistently higher during the second, which has significantly lowered the mortality rates. A functional link to winter temperature conditions was particularly stressed by the aetiology of individual plant vigour, injuries and final mortality. Classical symptoms of winter desiccation correlated significantly with low winter temperatures. This negative impact occurred with a high frequency during the decline phase and virtually ceased during the expansion phase from 1988 onwards, when winter air and root zone temperatures were raised to a consistently higher level. Winter and summer temperatures in the air and soil, as well as positive feedback mechanisms and nonlinear responses, must be taken into account in the search for global or regional mechanical explanations for the tree line phenomenon. This insight helps to generate realistic tree line models for a high‐CO2 world, when winter warming is usually predicted to be particularly large.

Cold tolerance of the sweet potato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae), from the Southwestern Islands of Japan

The cold tolerance of Cylas formicarius from five islands in the southwest of Japan was studied. The thermal threshold of the reproductive activity of adults tended to be lower and the supercooling point of the pupae was a little higher for the Okinawa-Honto population than for the others. The cold tolerance of the adult weevils was slightly accelerated by cold acclimation to 15°C for 4 d. Reproductive diapause induced under 10L : 14D increased cold tolerance significantly. Therefore, the cold tolerance of adult weevils would be accelerated by both cold acclimation at decreasing temperatures from autumn to winter and reproductive diapause induced by short daytime hours. When considering the increased cold-tolerence of C. formicarius through such mechanisms together with the temperature conditions in winter at the northern edge of its distribution area in the USA, C. formicarius probably has the capability to survive in the coastal zone of the Pacific Ocean in southern and central Japan.

Lessons from the unusual impacts of an abnormal winter in the USA

AbstractEconomic impacts from the near record warm and snow‐free winter of 2001–2 in the United States were assessed to ascertain their dimensions and relevance to issues like climate prediction and climate change. Unusual impacts resulted and embraced numerous sectors (heating/energy use, construction, tourism, insurance, government, and retail sales). Many outcomes were gains/benefits totalling $19.6 billion, with losses of $8.2 billion. Some economists identified the sizable positive impacts as a factor in the nation's recovery from an on‐going recession stemming from the terrorist attacks on 11 September 2001. Understanding the impacts of such a winter reveals how climate predictions of such conditions could have great utility in minimising the losses and maximising the gains. The results also have relevance to the global warming issue since most climate models project future average winter temperature and snowfall conditions in the United States to be similar to those experienced in 2001–2. Copyright © 2005 Royal Meteorological Society

Stability of Cyanogen Chloride in the Presence of Free Chlorine and Monochloramine

Cyanogen chloride (CNCl) is a disinfection byproduct found in chlorinated and chloraminated drinking water. Although there is an apparent greater association of CNCI with chloraminated water relative to chlorination systems, it was not clear whether these phenomenological observations are explained by differences in the stability or formation potentials of CNCI between the two disinfectants. In this study, the stability of CNCl was examined in the presence of free chlorine and monochloramine using membrane introduction mass spectrometry. CNCI decomposes relatively rapidly when free chlorine is present but is stable in the presence of monochloramine. The decomposition kinetics and observed reaction products are consistent with a hypochlorite-catalyzed hydrolysis mechanism, and the rate law is described by (d[CNCl]/dt) = - kOCl[CNCl][OCl-]. At 25 degrees C, pH 7, and a free chlorine residual of 0.5 mg/L as Cl2, the half-life of CNCl is approximately 60 min, suggesting significant decomposition is expected over disinfection time scales. Under some winter season temperature conditions, however, the decay half-life of CNCl can be longer than typical disinfection contact times. The results of this study demonstrate that the observed association of CNCl with chloramination systems can in part be explained by the differences in its stability with chlorine and chloramines.

The effect of low night temperatures on carbohydrates metabolism in developing pollen grains of pepper in relation to their number and functioning

Four pepper cultivars were grown under winter low night temperature (LNT) conditions (night temperature of 10±2 °C and day temperature which did not exceed 24 °C) in a greenhouse in Bet Dagan, Israel. In all four cultivars, LNT conditions caused a decrease in the number of pollen grains and a reduction in their germinability, in comparison with pollen of control plants grown in another greenhouse under higher temperature conditions (night temperature of 20±2 °C and similar day temperatures). Analysis of carbohydrates content in the later stages of pollen development revealed that LNT caused a reduction in starch concentration 4 days before anthesis (A-4), and in the concentrations of sucrose and reducing sugars (glucose and fructose) at anthesis (A). It is suggested that low temperatures hinder pollen functioning in pepper, by interfering with starch accumulation at A-4, thereby decreasing the concentrations of soluble sugars in the mature pollen grains. The fruits of the LNT-grown plants, except for cv. Devilla, were smaller, seedless and misshapen. The reason for the ability of cv. Devilla to set seeds and normal fruits under LNT conditions need further investigation.

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Diaphorina citri adults collected from Ishigaki Island (southern Ryukyus), Okinawa Island (central Ryukyus) and Amami Island (northern Ryukyus) were reared on Citrus unshiu and Murraya paniculata leaves under the late autumn to spring temperature conditions of 3 areas of Kyushu (south to north: Makurazaki, Akune, Kuchinotsu) located north of their natural habitat. About 60% of adults of Ishigaki population survived until late April at Makurazaki temperatures, at which time the survival rates of Okinawa and Amami populations had decreased below 14%. At temperatures in Akune, 35% of the Ishigaki population on M. paniculata and 10% on C. unshiu survived until late April, but the Okinawa and Amami populations died out before March. Under the conditions at Kuchinotsu with a minimum temperature of −3.3°C, only 4% of the Ishigaki population survived on M. paniculata and 6% on C. unshiu. Ishigaki adults reared on M. paniculata and Citrus limon trees at Makurazaki temperatures oviposited and progeny developed to the nymphal stage by the end of April. These results suggest that winter temperature conditions in parts of Kyushu are not destructive factors for D. citri populations.

休眠解除を考慮したソメイヨシノの開花日推定モデルの一般化

The generalization of model to estimate flowering dates for cherry trees (Prunus yedoensis) is attempted, considering processes both of endodormancy completion and development. As the basis of estimation, an accumulation model using an exponential function of daily mean temperature, called DTS (the number of days transformed to standard temperature) method, is used for expressing development of flower buds. The flowering date is estimated as the date on which the DTS, accumulated since a suitable starting date, reaches a predetermined DTS value. In this study, three models with different procedures to determine suitable starting data and DTS accumulations for flowering are constructed and verified, using data from meteorological stations in the warm region of Japan. The model A requires the complex procedure with analysis of previous temperature and phenological data to determine suitable starting date and DTS accumulations in each station, although this model gives accurate estimations. The generalized model B, without consideration of endodormancy completion process, includes the simplified procedure for determination of starting date and the constant DTS accumulations for flowering for all stations in Japan. However, in the warm region of Japan, interannual variation in advancement of the endodormancy completion process, which was influenced by winter temperature conditions, causes the change in the DTS accumulation required until the actual flowering date, and is attributed to the reduction in accuracy of estimations from models A and B. In generalized model C with consideration of endodormancy completion process, the suitable starting date is determined for each station, applying the equation, which includes some climatic and topographic factors, and the DTS accumulations for flowering are deduced as a function of the chill-unit accumulations, which represents the degree of endodormancy completion advancement in each year. On Hachijojima island, near the warm-side boundary for growing, model C reduced RMSE of estimates to 3.1 days from 6.4 days of that from model A. In the model verification using data from the warm region, the averages of RMSEs in estimations from models A, B and C were 2.7, 3.0 and 2.8 days, respectively. It means that the consideration of endodormancy completion process in model C compensated the decrease in model accuracy, which is attributed to introducing some simplified procedures into the model.

Overwintering and Growing Season Dynamics of Trifolium repens L. in Mixture with Lolium perenne L.: A Model Approach to Plant-environment Interactions

In attempting to increase the reliability of clover contribution in clover/ryegrass systems it is important to understand the roles of (1) specific traits of the clover genotype (2) climate and (3) their interactions in determining clover behaviour in swards. Overwintering and spring growth of white clover (cultivars AberHerald and Huia) grown in binary mixtures with perennial ryegrass were measured at 12 European sites ranging in latitude from Reykjavik, Iceland (64°30′ N) to Pordenone, Italy (46°30′ N). In the overwintering period, tiller density of the grass was assessed and detailed morphological and chemical measurements were made on the clover at each sampling time. During the growing season, the clover contribution to total available biomass was recorded. Detailed climatic data were available at all sites. The annual growth cycle of swards was divided into four functional periods (spring, summer, autumn and winter). Within each functional period community responses were modelled. The models incorporated independent biotic variables characterizing each community within each site at the start of the period and independent variables characterizing the climate at each site during the period. The models were linked dynamically by taking, as response variable(s) for a functional period, the independent biotic variable(s) of the succeeding period. In general, the modelling strategy was successful in producing a series of biologically meaningful linked models. Essential prerequisites for this were ( a) the establishment of a well-devised common protocol prior to the experiment and ( b) the extensive gradients of climatic and other variables obtained by using numerous sites. AberHerald generally performed as well as, or better than, Huia throughout the annual cycle across the range of climatic conditions encountered, and especially under low temperature conditions in winter and autumn. Clover leaf area index appeared to be a key variable in determining clover performance over winter and through the following growing season. Grass tiller density had a strong negative effect on clover content in spring but only at low temperatures. This emphasizes the importance of a high clover leaf area index in autumn as the main biotic factor related to spring clover content in milder conditions. The importance of climatic variables in the models is their use in explaining the reliability of the contribution of clover in clover/ryegrass systems. Temperature was the primary climatic determinant of clover response in all periods, having a direct effect on clover content and leaf area index or mediating the effect of the associate species. Radiation strongly influenced clover dynamics during winter and spring but not in the other periods, possibly because it was confounded with the effect of higher temperature. Precipitation was positively related to clover growth during spring and autumn and was related to tiller density in a complex manner during autumn and winter.

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.

Babesiosis (Babesia bovis) stability in unstable environments.

Enzootic stability (herd immunity) in bovine babesiosis occurs when the rate of transmission (inoculation rate) of Babesia spp by the tick vector is sufficient to immunize a majority of susceptible calves before the loss of calfhood resistance. The effect of three tick (Boophilus microplus) control strategies (none, threshold, and strategic) on enzootic stability and the likelihood of babesiosis (Babesia bovis) outbreaks was studied using a spreadsheet age-class computer simulation model. The model was driven by weekly bovine tick counts from Brazil and Uruguay. The Eldorado do Sul, RS, Brazil bovine population (30 degrees 05' South latitude) was found to be in a naturally occurring state of enzootic stability, corresponding to an inoculation rate exceeding 0.005 throughout the year. Threshold dipping strategies should not increase the risk of babesiosis in cattle so managed. Strategic dipping resulted in an extended period of enzootic instability lasting 30 weeks, which requires protection of the herd through immunization. Because of the more prolonged low winter temperature conditions, the Tacuarembó, Uruguay bovine population (31 degrees 40' South latitude) was found to be in a naturally occurring state of enzootic instability, characterized by a 28 week period in which the inoculation rate was below 0.005. Strategic dipping should lead to eradication of the babesial parasite from tick and bovine populations, but would not result in eradication of the tick vector. This could lead to subsequent outbreaks if Babesia carrier animals were to be introduced into the herd. In both populations, strategic tick control could be accompanied by concurrent babesiosis vaccination.

Advanced Nitrogen Removal by Rotating Biological Contactors, Recycle and Constructed Wetlands

The sewage treatment facility at Himley comprises Rotating Biological Contactors (RBCs) and subsurface flow constructed reed beds in series. A recycle facility returns RBC effluent to the influent flow. Effluent total nitrogen (TN) has always been low since commissioning and the reasons were investigated. Denitrification was observed to occur in the primary settlement tank. High hydraulic loadings in the RBC biozone deteriorated BOD5 and TSS removal, but good nitrification was obtained. The relatively poor effluent from the RBC gave a carbon source allowing further denitrification through the reed beds. Ammonification caused an increase in ammoniacal nitrogen across the primary reed bed in summer. At this time strongly reducing conditions occurred within the reed beds which, in the absence of dissolved oxygen and oxidised nitrogen compounds, led to sulphate reduction and sulphide formation with odour generation. These problems were not observed at low winter temperature conditions. Effluent TN was always below 0 mg/l.

Advanced nitrogen removal by rotating biological contactors, recycle and constructed wetlands

The sewage treatment facility at Himley comprises Rotating Biological Contactors (RBCs) and subsurface flow constructed reed beds in series. A recycle facility returns RBC effluent to the influent flow. Effluent total nitrogen (TN) has always been low since commissioning and the reasons were investigated. Denitrification was observed to occur in the primary settlement tank. High hydraulic loadings in the RBC biozone deteriorated BOD, and TSS removal, but good nitrification was obtained. The relatively poor effluent from the RBC gave a carbon source allowing further denitrification through the reed beds. Ammonification caused an increase in ammoniacal nitrogen across the primary reed bed in summer. At this time strongly reducing conditions occurred within the reed beds which, in the absence of dissolved oxygen and oxidised nitrogen compounds, led to sulphate reduction and sulphide formation with odour generation. These problems were not observed at low winter temperature conditions. Effluent TN was always below 10 mg/1.

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.

Two-Dimensional Air Exfiltration and Heat Transfer Through Fiberglass Insulation I. Numerical Model and Experimental Facility

A numerical model, employing a local-averaging formulation, was developed for heat transfer and water vapor deposition within fiberglass insulation under air exfiltration and frosting conditions. Frost growth on the cold surface was modeled using special frost growth boundary conditions. Non-isotropic permeability effects that occur in fiberglass boards were included in the model for porous medium flow because tests showed that the permeability for flow parallel to the plane of the boards was 69% higher than perpendicular to the insulation boards. Transient heat and moisture transfer processes within a thick layer of fiberglass insulation were modeled for steady exfiltration of humid air (60% to 84% rh) with a two-dimensional airflow during winter temperature conditions. In order to validate the numerical model, laboratory apparatus was constructed with a test cell 135 mm high, 600 mm wide and 275 mm deep. This allowed a two-dimensional moist air exfiltration [0.5 to 1.5 L/(m2·s)] through a fiberglass insulation slab for a temperature range −20°C to 21.5°C from the cold outside surface to the warm inside surface. Using this apparatus, the transient temperature profiles, moisture accumulation profiles, and heat-flux at the cold side of the fiber-glass insulation were measured during the air exfiltration process. Part I outlines the theoretical/numerical model and describes the experimental test facilities and the properties of the fiberglass insulation tested. Part II of this paper presents the comparisons of experimental data and corresponding simulation results.

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.

Low Temperatures Affect the Photoperiodically Induced LH and Testicular Cycles Differently in Closely Related Species of Tits ( Parus spp.)

Photosensitive great tits ( Parus major) and willow tits ( P. montanus) were exposed to long days (20L:4D) under three different temperature conditions (+4, + 10, and + 20°C) in early winter. The two species showed significant differences in their LH and testicular reaction patterns to low temperatures. Testes showed pronounced growth cycles under all temperature regimes. For the willow tit, testes in birds kept at +20°C reached maximum size about 2 weeks earlier than testes in birds living under the two lower temperature regimes, whereas in the great tit testes reached maximum size at about the same time in all three groups. Low temperatures delayed the onset of testicular regression in both species. Plasma levels of LH did change with time in both species. However, the patterns of the induced LH-cycles in the three great tit groups differed significantly from each other, whereas this was not the case for the willow tits. The LH cycle was especially pronounced in great tits kept at +20°C. The initial LH peak in great tits kept at +4 and +10°C was about 50% lower than in great tits kept at +20°C. These results are discussed in relation to species differences in winter ecology and establishment of breeding territories.

Primary biodegradation kinetics of linear alkylbenzene sulphonates in estuarine waters

Primary biodegradation kinetics of a typical commercial mixture of linear alkylbenzene sulphonates (LAS), containing alkyl homologues in the range of C 10 to C 13, has been investigated using three mixed bacterial cultures. Two of the cultures originated from the Krka River Estuary (freshwater layer and saline layer) while the third one originated from the adjacent coastal waters. Determination of the remaining LAS during the biodegradation experiments was performed using reversed-phase high-performance liquid chromatography (HPLC) which allowed specific determinations of individual homologues and/or isomers. Results obtained under static conditions (die-away method) have shown that the biodegradation rate depended strongly upon the origin of the bacterial culture, the temperature condition, and the structure of alkylbenzene moiety. The mixed bacterial culture originating from the freshwater layer of the estuary revealed a significantly greater ability to degrade LAS than that from the underlying saline water layer or from the reference marine station. The biodegradation rate was significantly higher in summer (23°C) than in winter (14°C) temperature conditions. When comparing biodegradation rates of the individual homologues, the highest rate was observed for those with the longest alkyl chain. For different isomers of the same homologue, it has been noticed that biodegradation rate increased with increasing distance of the sulphophenyl group from the terminal methyl group.

Evaluation of Cold Temperatures and Density as Mortality Factors of the Eucalyptus Longhorned Borer (Coleoptera: Cerambycidae) in California

It was hypothesized that the northward spread of the eucalyptus longhorned borer, Phoracantha semipunctata F., in California is limited by winter temperature conditions. The cold tolerance of prepupal stages was tested by exposing infested logs to cold temperature treatments of −5,0, +5, and +10°C for periods of 1, 3, 7, and 30 d. Temperature treatments had no affect on survivorship to adulthood or longevity but did reduce adult weight relative to nontreated control logs. Increasing exposure time to all cold temperatures significantly reduced both survivorship and adult weight but had no affect on adult longevity. Long periods of exposure to cold temperatures delayed emergence of adults and resulted in more closely synchronized emergence. Cold temperatures are unlikely to prevent the spread of this pest into most zones occupied by its eucalyptus host plants. In addition, increasing densities of prepupae in logs also resulted in significantly reduced survivorship to adulthood but did not affect adult weight or longevity.

The effects of temperature, pH and water hardness on winter starvation of young‐of‐the‐year smallmouth bass, Micropterus dolomieui Lacepede

Year‐class strength in northern populations of smallmouth bass is strongly influenced by winter starvation of young‐of‐the‐year. We examined starvation among young bass under both winter and summer light and temperature conditions. During starvation, body condition declines to a specific level and then the fish dies. Body condition at death is a well defined function of body size that remains relatively constant over a wide range of environmental conditions. Starvation rate varies systematically with body size, temperature, pH and water hardness. Available stored energy increases more rapidly with body size than starvation rate. Therefore, lifetime under starvation conditions tends to increase with increasing body size. The Q10 for starvation rate over the temperature range 2.5‐8° C is 2.2. Starvation rate increases as pH declines from 7.0‐4.9: the rate at pH 4.9 is ∼ 1.25 times the rate at pH 7 Starvation rate decreases as Ca concentration increases from 1 mgl−1 to 80mgl−1: the rate at 80 mg Ca 1−1 is ∼0.80 times the rate at 1 mgl−1.

The Importance of the Acidogenic Microflora in Biological Phosphorus Removal

Laboratory and semi-industrial scale pilot plant experiments were carried out to study the possibility of simultaneous biological nitrogen and phosphorus removal under European winter temperature conditions. Whereas nitrogen removal requires very long aerated sludge ages, phosphorus removal seems to be somewhat inhibited by the low sludge loadings. Experiments with fatty acid addition to the influent wastewater have shown the acidogenic phase to be the step that was most affected by these low load conditions. The phosphorus release and uptake mechanism in itself may be slowed down by lower temperatures, but still has some activity. A microbiological study of the organisms in the sludge was undertaken in order to discover which organisms were responsible for the different steps in the phosphorus removal mechanism.