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Competition in mesic sites and drought stress combined with short growing seasons in drier sites are key environmental factors along macroclimatic aridity gradients. They impose a triangular trade‐off for local adaptation. However, as experiments have rarely disentangled their effects on plant fitness, uncertainty remained whether mesic populations are indeed better competitors and drier populations better adapted to drought stress and short season length. Aridity differs also at microclimatic scale between north (more mesic) and south (more arid) exposed hill‐slopes. Little is known whether local adaptation occurs among exposures and whether south exposures harbor conspecifics better adapted to drier climates that could provide adaptive reservoirs under climate change. We sampled two Mediterranean annuals (Brachypodium hybridum, Hedypnois rhagadioloides) in 15 sites along a macroclimatic aridity gradient (89–926 mm rainfall) on corresponding north and south exposures. In a large greenhouse experiment, we measured their fitness under drought stress, competition, and short vs. long growing seasons. Along the macroclimatic gradient, mesic populations were better competitors under benign conditions. Drier populations performed no better under drought stress per se but coped better with the short growing seasons typical for drier macroclimates. At microclimatic scale, north exposure plants were slightly better competitors in H. rhagadioloides; in B. hybridum, south exposure plants coped better with drought under short season length. We demonstrate that local adaptation to drier macroclimates is trading‐off with competitive ability under benign conditions and vice‐versa. Drought escape via short life‐cycles was the primary adaptation to drier macroclimates, suggesting that intensified drought stress within the growing season under climate change challenges arid and mesic populations alike. Moreover, the drier microclimates at south exposures exhibited some potential as nearby reservoirs of drier‐adapted genotypes. This potential needs further investigation, yet may assist populations to persist under climate change and lessen the need for long‐distance migration. [ABSTRACT FROM AUTHOR]

Ecological and social factors shape individual reproductive strategies. Climate change has wide‐ranging effects on the timing of reproduction and availability of nesting sites for many birds. Ecological factors such as season length or predation rate could in turn affect the relative success rates of alternative reproductive tactics (ARTs). A new article by Pöysä (2024) featuring a long‐term study of common goldeneyes Bucephala clangula highlights the role of climate change in altering rates of conspecific brood parasitism (CBP) by affecting nest initiation dates and season length. While some authors have emphasized the effects of spatial and temporal aggregation of nests in promoting tactics of reproductive interference, few studies have addressed the effects of environmental variables on rates of CBP and other ARTs. I review some of the evidence for a relationship between population‐level nest predation rate and rates of CBP, principally in ducks and rails, and suggest a role for high rates of nest loss from all sources in the evolution of CBP and host responses. There is a need for further studies that examine environmental correlates of ARTs. Long‐term studies have the highest potential to reveal how shifts in phenology and life history variables may respond to environmental perturbations. Comparative studies of similar species in remote geographic locations can add perspective of how different ecological variables affect the prevalence of ARTs. [ABSTRACT FROM AUTHOR]

Changing global fire regimes including extended fire seasons due to climate change may increase the co-occurrence of high-impact fires that overwhelm national fire suppression capacities. These shifts increase the demand for international resource sharing to supplement national fire suppression efforts. In this paper, we explore the development and evaluate the effectiveness of international resource sharing arrangements of three regions: (1) The United States, Canada, and Australia (“Big Three”); (2) Europe; and (3) Southeast Asia by conducting a literature review of gray and peer- reviewed literature in combination with key informant interviews. For the “Big Three” and Europe, international resource sharing is perceived as necessary, effective, and continuously improving. Converging fire management processes and training and developing more effective administrative procedures facilitate these relationships. In Southeast Asia, political tensions and limited firefighting capacities have hampered effective cooperation. Formalized agreements of country-to-country support for fire management are nascent and evolving, and there is evidence that demand for expanding and improving these partnerships is increasing.

Background and aims Perennial plants in seasonal climates need to optimize their carbon balance by adjusting their active season length to avoid risks of tissue loss under adverse conditions. As season length is determined by two processes, namely spring growth and senescence, it is likely to vary in response to several potentially contrasting selective forces. Here we aim to disentangle the cascade of ecological determinants of interspecific differences in season length. Methods We measured size trajectories in 231 species in a botanical garden. We examined correlations between their spring and autumn size changes and determined how they make up season length. We used structural equation models (SEMs) to determine how niche parameters and species traits combine in their effect on species-specific season length. Key results Interspecific differences in season length were mainly controlled by senescence, while spring growth was highly synchronized across species. SEMs showed that niche parameters (light and moisture) had stronger, and often trait-independent, effects compared to species traits. Several niche (light) and trait variables (plant height, clonal spreading) had opposing effects on spring growth and senescence. Conclusions The findings indicate different drivers and potential risks in growth and senescence. The strong role of niche-based predictors implies that shifts in season length due to global change are likely to differ among habitats and will not be uniform across the whole flora. [ABSTRACT FROM AUTHOR]

To predict species' responses to a rapidly changing environment, it is necessary to detect current clines of life-history traits and understand their drivers. We studied body size variation, a key trait in evolutionary biology, of two arctic–alpine lycosid spiders and underlying mechanisms controlling this variation. We used long time-series data of body size of spiders sampled in Norway, augmented with museum data. Individuals of both species sampled in areas and years with longer snow-free periods grew larger than individuals in areas and years with shorter snow-free periods. Interestingly, temperatures below 0 °C led to a larger body size in Pardosa palustris , while temperatures above 0 °C led to a larger body size in Pardosa hyperborea. We assume that P. palustris , as the generally larger species, is less sensitive to environmental variability and low temperatures, because it can retain more energy compared with a smaller species and, therefore, can invest more resources in its offspring. With rising temperatures, both species might profit from a higher resource availability. In a rapidly changing arctic–alpine environment, alterations in the life-history traits and adaptation strategies of spiders are expected, which, regarding body size, seem to be highly influenced by early snowmelt and diverging thermal constraints. [ABSTRACT FROM AUTHOR]

This study addresses the impact of climate change (2021-2080) on the seasonal distribution of rainfall, temperature, and season lengths over Iran under three Shared Socioeconomic Pathways (SSPs) of the low (SSP1-1.9), moderate (SSP2-4.5), and high (SSP5-8.5) levels of global warming, based on the 29 model ensemble of the Coupled Model Inter-comparison Project Phase 6 (CMIP6). Results reveal that spring and autumn lengths are ~ 90 days during the baseline period (1980-2014), while summer (~ 97 days) is longer than winter (~ 87 days) by 10 days. However, global warming will result in longer summer and winter and shorter spring and autumn seasons in the future. The temperature will increase during all four seasons of spring and autumn (1.5-2.7 ∘ C ), winter (1.1-2.2 ∘ C ), and summer (2.0-3.2 ∘ C ) consistently with the level of global warming scenarios. Meanwhile, minimum and maximum temperature enhancement will occur during winter and summer, respectively, under a given climate change scenario. Rainfall over Iran will increase during all seasons (6-36%) under SSP1-1.9 but will reduce under warmer scenarios SSP2-4.5 (12-24%) and SSP5-8.5 (8-24%). The contributions of the spring, summer, autumn, and winter seasons to the annual rainfall are 32%, 5%, 20%, and 43%, respectively, implying winter and spring as wet seasons during the baseline period. However, climate change may shift the wet season from winter to spring or autumn, depending on the station and SSP, under climate change. Water managers and policymakers need to consider the highlighted issues for future sustainable management in Iran., Competing Interests: Declarations. Ethical approval: The author declares that the manuscript is prepared and submitted in compliance with ethical approval. Consent to participate: Informed consent was obtained from all individual participants included in the study. Consent for publication: The author declares his consent to publication of the manuscript. Competing interests: The author declares no competing interests., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Climate change is expected to alter primary production and community composition in alpine ecosystems, but the direction and magnitude of change is debated. Warmer, wetter growing seasons may increase productivity; however, in the absence of additional precipitation, increased temperatures may decrease soil moisture, thereby diminishing any positive effect of warming. Since plant species show individual responses to environmental change, responses may depend on community composition and vary across life form or functional groups. We warmed an alpine plant community at Niwot Ridge, Colorado continuously for four years to test whether warming increases or decreases productivity of life form groups and the whole community. We provided supplemental water to a subset of plots to alleviate the drying effect of warming. We measured annual above-ground productivity and soil temperature and moisture, from which we calculated soil degree days and adequate soil moisture days. Using an information-theoretic approach, we observed that positive productivity responses to warming at the community level occur only when warming is combined with supplemental watering; otherwise we observed decreased productivity. Watering also increased community productivity in the absence of warming. Forbs accounted for the majority of the productivity at the site and drove the contingent community response to warming, while cushions drove the generally positive response to watering and graminoids muted the community response. Warming advanced snowmelt and increased soil degree days, while watering increased adequate soil moisture days. Heated and watered plots had more adequate soil moisture days than heated plots. Overall, measured changes in soil temperature and moisture in response to treatments were consistent with expected productivity responses. We found that available soil moisture largely determines the responses of this forb-dominated alpine community to simulated climate warming.

Individual fishing quotas give fishers incentives to reduce costs (or increase productivity), lengthen the harvest season and increase price by improving catch quality. To what extent each of these three effects will be present when the management system is changed in a specific fishery depends on the characteristics of the fishery and on the markets and supply chains served. This paper uses a difference-in-differences approach to investigate the impact on all three outcomes of a regulatory change that introduced individual fishing quotas with some transferability for a group of coastal vessels in the Norwegian whitefish fisheries. The results indicate higher ex-vessel prices after the regulatory change, which imply higher quality of the fish landed, but show no significant extension of the fishing season or reduction of the average cost. [ABSTRACT FROM AUTHOR]

Climate change has shifted geographical ranges of species northwards or to higher altitudes on elevational gradients. These changes have been associated with increases in ambient temperatures. For ectotherms in seasonal environments, however, life history theory relies largely on the length of summer, which varies somewhat independently of ambient temperature per se. Extension of summer reduces seasonal time constraints and enables species to establish in new areas as a result of over-wintering stage reaching in due time. The reduction of time constraints is also predicted to prolong organisms' breeding season when reproductive potential is under selection. We studied temporal change in the summer length and its effect on species' performance by combining long-term data on the occurrence and abundance of nocturnal moths with weather conditions in a boreal location at Värriötunturi fell in NE Finland. We found that summers have lengthened on average 5 days per decade from the late 1970s, profoundly due to increasing delays in the onset of winters. Moth abundance increased with increasing season length a year before. Most of the species occurrences expanded upwards in elevation. Moth communities in low elevation pine heath forest and middle elevation mountain birch forest have become inseparable. Yet, the flight periods have remained unchanged, probably due to unpredictable variation in proximate conditions (weather) that hinders life histories from selection. We conclude that climate change-driven changes in the season length have potential to affect species' ranges and affect the structure of insect assemblages, which may contribute to alteration of ecosystem-level processes. [ABSTRACT FROM AUTHOR]

A field experiment was conducted during with three sowing dates (23 June, 8 July and 23 July) with three varieties (JS 20-29, JS 20-34 and JS 97-52) kharif season of 2016 and 2017 at Jabalpur in eastern Madhya Pradesh for assessing crop weather relationship in soybean through thermal and radiation environments. The results revealed that early sown crop attained more accumulated heat units, and yield decreased with delay in sowing. The maximum and minimum temperatures during reproductive stage were positively correlated with seed yield while negatively associated with vegetative and pod development stages. Photosynthetic active radiation absorption (APAR) was maximum in June sowing in semi-determinate JS 97-52 variety at pod formation stage. Maximum leaf area index (LAI) exhibited in June sown for JS 97-52 variety during pod formation stage. Seed yield increase with increased in APAR and LAI during pod formation stage. Season length difference between normal and actual crop maturity period increased with the decrease in GDD thereby suggesting a decline in yield due to shortening of crop growing period.

Comparative studies, across and within taxa, have made important contributions to our understanding of the evolutionary processes that promote phenotypic diversity. Trait variation along geographic gradients provides a convenient heuristic for understanding what drives and maintains diversity. Intraspecific trait variation along latitudinal gradients is well‐known, but elevational variation in the same traits is rarely documented. Trait variation along continuous elevational gradients, however, provides compelling evidence that individuals within a breeding population may experience different selective pressures.Our objectives were to quantify variation in a suite of traits along a continuous elevational gradient, evaluate whether individuals in the population experience different selective pressures along that gradient and quantify variation in migratory tendency along that gradient.We examined variation in a suite of 14 life‐history, morphological and behavioural traits, including migratory tendency, of yellow‐eyed juncos along a continuous 1000‐m elevational gradient in the Santa Catalina Mountains of Arizona.Many traits we examined varied along the elevational gradient. Nest survival and nestling growth rates increased, while breeding season length, renesting propensity and adult survival declined, with increasing elevation. We documented the migratory phenotype of juncos (partial altitudinal migrants) and show that individual migratory tendency is higher among females than males and increases with breeding elevation.Our data support the paradigm that variation in breeding season length is a major selective pressure driving life‐history variation along elevational gradients and that individuals breeding at high elevation pursue strategies that favour offspring quality over offspring quantity. Furthermore, a negative association between adult survival and breeding elevation and a positive association between nest survival and breeding elevation help explain both the downslope and reciprocal upslope seasonal migratory movements that characterize altitudinal migration in many birds. Our results demonstrate how detailed studies of intraspecific variation in suites of traits along environmental gradients can lend new insights into the evolutionary processes that promote diversification and speciation, the causes of migratory behaviour, and how animal populations will likely respond to climate change. [ABSTRACT FROM AUTHOR]

Summary: Species are commonly distributed along latitudinal and elevational gradients of growing season length to which they might respond via phenotypic plasticity and/or adaptive genetic differentiation. However, the relative contribution of these processes and whether plasticity, if it occurs, facilitates expansion along season‐length gradients remain unclear, but are important for predicting species fates during anthropogenic change.We quantified phenological trait variation in the montane annual Rhinanthus minor for three generations at 12 sites across 900 m of elevation in the Canadian Rocky Mountains and conducted a reciprocal transplant experiment for two generations among nine sites. We compared clines and interannual variation of phenological traits between natural and transplanted individuals.Season length declined by c. 37% along our elevational gradient and, as expected, plants emerged, reached first flower and made their first seed in c. 41% fewer growing degree days under shorter growing seasons. Although reciprocal transplants revealed modest genetic differentiation across elevation, trait clines primarily were due to striking co‐gradient plasticity that paralleled genetic differentiation.Co‐gradient plasticity likely evolved in response to considerable interannual variation in season length across our elevational transect, and should prepare R. minor to make adaptive changes to phenology in response to ongoing climate change predicted for montane environments. See also the Commentary on this article by Wadgymar & Austen, 224: 1009–1011. [ABSTRACT FROM AUTHOR]

The Sierra Nevada yellow-legged frog (Rana sierrae) was once an abundant and widely distributed amphibian in California's alpine ranges. Rana sierrae is adapted to high-elevation, fishless habitats. Its adaptions are reflected in a unique life cycle that involves a flexible, extended juvenile phase due to the short growing season typical of its alpine habitat. However, today this species is critically endangered, and most populations have been extirpated from their native range. Here, we present an 18-yr-long demographic study of a R. sierrae population in 15 lakes at Dusy Basin in Kings Canyon National Park. We focused on the period leading up to the arrival of the pathogenic chytrid fungus, Batrachochytrium dendrobatidis (Bd), and the subsequent local extinction of R. sierrae. We used N-mixture abundance modeling, which accounts for detection probabilities, to quantify factors affecting frog abundance at different life stages. The abundance of subadult and adult frogs was negatively associated with the presence of introduced trout (Oncorhynchus mykiss and O. aquabonita). Frog abundance in all life stages was positively associated with lake surface area. The propensity of lakes drying correlated negatively with abundance of eggs, subadults, and adults in the following year. Moreover, drought years, characterized by longer summers and less winter snowpack, led to higher rates of lakes drying. Finally, our results suggest that the frequency of such droughts in the region has increased since 1937. Increased frequency or severity of droughts is expected to decrease the value of shallow lakes for Sierra Nevada yellow-legged frogs because these habitats are prone to drying.We discuss our results in terms of future restoration strategies, including reintroduction and probiotic treatment, in this changed and changing ecosystem. [ABSTRACT FROM AUTHOR]

Recent climate warming is expected to have changed the phenology of organisms. The cricket Dianemobius nigrofasciatus (Matsumura) (Orthoptera: Trigonidiidae) has univoltine and bivoltine life cycles in northern and southern regions of Japan, respectively, because of latitudinal variation in the growing season length. Its adult body size increases with decreasing latitude, and decreases at a latitude where the number of annual generations increases. The present study aims to examine whether the range of the bivoltine life cycle has expanded northward due to climate warming. We compared a latitudinal saw-tooth body size cline between the 1960s and the 2010s. The body size showed a latitudinal saw-tooth cline in adults collected in recent years, as it did in adults collected five decades ago. However, no significant difference was observed between these two clines, suggesting that the bivoltine life cycle has not expanded in the last five decades. These results contrast to those recently reported in a closely related species, Polionemobius mikado (Shiraki) (Orthoptera: Trigonidiidae), in which the turning points of the saw-tooth cline had shifted northward in the last four decades. The stable latitudinal distribution of life cycles in D. nigrofasciatus might result from the different photoperiodic regulation of growth rate involved in the different responses to climate warming. [ABSTRACT FROM AUTHOR]

Major League Soccer (MLS) has aggressively expanded from 10 teams to 23 teams. With the addition of more teams, the league will have to dictate a schedule that maximizes the league's popularity, while also maintaining the health of the players. A longer season and congested game schedule could increase the risk of injury for players. The purpose of this commentary is to make recommendations for the prevention of injuries among MLS players with respect to proposed league expansion. MLS has lengthened the regular season with each expansion in teams. An increase in season length was seen in conjunction with the MLS expansion from 14 to 19 teams during the 2008 through 2013 seasons. Data from the inaugural MLS season found injury rates were higher in games compared to practices and more injuries occurred later in the season. With the expansion of MLS, anterior cruciate ligament tears appeared to have increased each year. Current evidence suggests the implementation of a proper preseason in addition to the once-per-week game frequency would best promote player health and well-being. Players may benefit from in-season injury prevention training and weekly load monitoring. • MLS has expanded from 10 teams to 23 teams, with plans to increase to 28 teams. • Research shows increased injury rates with congested schedules and longer seasons. • MLS has congested the schedule & increased season length to accommodate more teams. • There is a paucity of research specific to MLS to guide injury prevention. • Further investment in research and rehabilitation staff is necessary. [ABSTRACT FROM AUTHOR]

Abstract: The theory of life‐history evolution investigates how growth‐reproduction trade‐offs drive evolution of body size in uni‐ and multivoltine (one or more generations per year) arthropods. Existing theory does not predict how the length of the feeding season (season length hereafter) affects body size in semivoltine (i.e., juvenile period longer than 1 year) determinate growers and usually ignores that uni‐ and semivoltine arthropods accumulate large reserves to cover costs of diapause and future reproduction. Here, we present how the trade‐offs between growth, storage and reproduction drive evolution of body mass and reproductive strategy in arthropods with determinate growth. Our life‐history model concerns high‐latitude marine copepods living in a strongly seasonal environment. We find that small changes in season length and mortality rate translate into abrupt shifts in lean body mass (a proxy for body size). Body size shifts are caused by a change from multi‐ to uni‐ and semivoltine life cycles with semivoltine life histories selected for in short seasons and only if background mortality is low. Shifts in the number of generations per year do not translate into shifts in the mass of lipid reserves. The model predicts less reserves the shorter the winter. Season length alone is not a sufficient predictor of the degree of capital breeding. Storing for reproduction is strongly selected for under short season but low mortality rate. Hence, capital breeding contributes to fitness in uni‐ and semivoltine organisms whereas multivoltines are income breeders. We also show that storing reserves for diapause and capital breeding trades off with adult size of determinately growing arthropods. Our results, in particular regarding optimal body size, reproductive strategy (income‐to‐capital breeding) and degree of storage are relevant to a number of determinate growers, including insects and crustaceans. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Ensing & Eckert, 224: 1184–1200. [ABSTRACT FROM AUTHOR]

Aim General geographical patterns of insect body size are still a matter of considerable debate, mainly because the annual number of generations (voltinism) and its relationship with body size have largely been ignored. We present the first analyses of voltinism and body size of insect assemblages at a continental scale using lepidopteran and odonate species. We hypothesize that voltinism is strongly driven by environmental conditions and constrains body size on macroecological scales. Location Europe. Methods We compiled the distribution, voltinism and body size of 943 lepidopteran and odonate species within a 50 km × 50 km grid system, thereby presenting a novel method for estimating the body volume of species from digital images. Regressions and structural equation modelling were applied to distinguish the effects of temperature, productivity and season length on mean voltinism and body size within grid cells. We accounted for spatial autocorrelation with autoregressive models and analysed the possible effect of species richness and intraspecific variability. Results Voltinism consistently decreased with latitude for both lepidopterans ( r2 = 0.76) and odonates ( r2 = 0.86), with species having on average fewer generations per year in northern Europe and more generations per year in southern Europe. The effects of temperature, productivity and season length on body size contrasted in sign between lepidopterans and odonates, leading to opposing geographical patterns across Europe. Main conclusions Voltinism in insect assemblages is strongly driven by environmental temperature, and trade-offs between voltinism and body size influence the occurrence of species at macroecological scales. Insects with the ability to extend their generation time over multiple years can overcome this constraint, allowing for a relatively large body size in cold areas. Our results furthermore support the idea that body sizes of terrestrial and aquatic insects form contrasting geographical patterns because they are differently affected by temperature and resource constraints. [ABSTRACT FROM AUTHOR]

Climate warming is strongly altering the timing of season initiation and season length in the Arctic. Phenological activities are among the most sensitive plant responses to climate change and have important effects at all levels within the ecosystem. We tested the effects of two experimental treatments, extended growing season via snow removal and extended growing season combined with soil warming, on plant phenology in tussock tundra in Alaska from 1995 through 2003. We specifically monitored the responses of eight species, representing four growth forms: (i) graminoids ( Carex bigellowii and Eriophorum vaginatum); (ii) evergreen shrubs ( Ledum palustre, Cassiope tetragona, and Vaccinium vitis-idaea); (iii) deciduous shrubs ( Betula nana and Salix pulchra); and (iv) forbs ( Polygonum bistorta). Our study answered three questions: (i) Do experimental treatments affect the timing of leaf bud break, flowering, and leaf senescence? (ii) Are responses to treatments species-specific and growth form-specific? and (iii) Which environmental factors best predict timing of phenophases? Treatment significantly affected the timing of all three phenophases, although the two experimental treatments did not differ from each other. While phenological events began earlier in the experimental plots relative to the controls, duration of phenophases did not increase. The evergreen shrub, Cassiope tetragona, did not respond to either experimental treatment. While the other species did respond to experimental treatments, the total active period for these species did not increase relative to the control. Air temperature was consistently the best predictor of phenology. Our results imply that some evergreen shrubs (i.e., C. tetragona) will not capitalize on earlier favorable growing conditions, putting them at a competitive disadvantage relative to phenotypically plastic deciduous shrubs. Our findings also suggest that an early onset of the growing season as a result of decreased snow cover will not necessarily result in greater tundra productivity. [ABSTRACT FROM AUTHOR]

The most essential requirement for water management is efficient and informative monitoring. Operating water quality monitoring networks is a challenge from both the scientific and economic points of view, especially in the case of river sections ranging over hundreds of kilometers. Therefore, spatio-temporal optimization is vital. In the present study, the optimization of the monitoring system of the River Tisza, the second largest river in Central Europe, is presented using a generally applicable and novel method, combined cluster and discriminant analysis (CCDA). This area for the study was chosen because, spatial inhomogeneity of a river's monitoring network can more easily be studied in a mostly natural watershed - as in the case of the River Tisza - since the effects of man-made obstacles: e.g water barrage systems, hydroelectric power plants, artificial lakes, etc. are more pronounced. Furthermore, since the temporal sampling frequency was bi-weekly, the opportunity of optimizing the monitoring system on a temporal (monthly) scale arose. In the research, 15 water quality parameters measured at 14 sampling sites in the Hungarian section of the River Tisza were assessed for the time period 1975-2005. First, four within-year sections ('hydrochemical seasons') were determined, characterized with unequal lengths, namely 2, 4, 2, and 4 months long starting with spring. Homogeneous groups of sampling sites were determined in space for every season, with the main separating factors being the tributaries and man-made obstacles. Similarly, an overall pattern of homogeneity was determined. As an overall result, the 14 sampling sites could be grouped into 11 homogeneous groups leading to the possibility of reducing the number of sampling locations and thus making the monitoring system more cost-efficient. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This paper focussed on the analysis of season division and season length in Luan River Basin based on the data of daily mean temperature observed at 24 weather stations from 1957 to 2012. The whole basin was divided into three parts according to the surface roughness characteristics. The spatial and temporal variation of season division and season length was estimated by means of the definition of climatic season, linear regression analysis, and inverse distance weighted analysis. The results indicated that the starting dates of autumn and winter were delayed from upper to lower reaches, while that of spring was advanced. The season length of spring and winter generally decreased from upper to lower reaches, while that of summer increased. During the past 56 years, the starting dates of summer/autumn/winter were all 4~20d late, while spring was 10~15d earlier; the season length of winter decreased by 15~21d, whereas that spring and summer increased by 3~11d and 17~19d, respectively. [ABSTRACT FROM AUTHOR]

Allergenic pollen is one of the main triggers of Allergic Airway Disease (AAD) affecting 5%–30% of the population in industrialized countries. A modeling framework has been developed using correlation and collinearity analyses, simulated annealing, and stepwise regression based on nationwide observations of airborne pollen counts and climatic factors to predict the onsets and durations of allergenic pollen seasons of representative trees, weeds and grass in the contiguous United States. Main factors considered are monthly, seasonal and annual mean temperatures and accumulative precipitations, latitude, elevation, Growing Degree Day (GDD), Frost Free Day (FFD), Start Date (SD) and Season Length (SL) in the previous year. The estimated mean SD and SL for birch ( Betula ), oak ( Quercus ), ragweed ( Ambrosia ), mugwort ( Artemisia ) and grass ( Poaceae ) pollen season in 1994–2010 are mostly within 0–6 days of the corresponding observations for the majority of the National Allergy Bureau (NAB) monitoring stations across the contiguous US. The simulated spatially resolved maps for onset and duration of allergenic pollen season in the contiguous US are consistent with the long term observations. [ABSTRACT FROM AUTHOR]

Different genotypes often exhibit opposite plastic responses in the timing of the onset of flowering with increasing plant density. In experimental studies, selection for accelerated flowering is generally found. By contrast, game theoretical studies predict that there should be selection for delayed flowering when competition increases., Combining different optimality criteria, the conditions under which accelerated or delayed flowering in response to density would be selected for are analysed with a logistic growth simulation model., To maximize seed production at the whole-stand level (simple optimization), selection should lead to accelerated flowering at high plant density, unless very short growing seasons select for similar onset of flowering at all densities. By contrast, selection of relative individual fitness will lead to delayed flowering when season length is long and/or growth rates are high., These different results give a potential explanation for the observed differences in direction of the plastic responses within and between species, including homeostasis, as a result of the effect of the variation in season length on the benefits of delayed flowering. This suggests that limited plasticity can evolve without the costs and limits that are currently thought to constrain the evolution of plasticity. [ABSTRACT FROM AUTHOR]

Temperature is one of the most important drivers of range limits in plants. Here, we aimed at disentangling the direct effect of low temperature and the indirect temperature effect via the length of the growing season on radial growth and carbon resources of deciduous temperate tree species at their high-elevation limit in the Swiss Alps., Trees of eight species were cored along three elevational gradients of ca. 1000 m up to the specific high-elevation range limit. We correlated basal area increment ( BAI) with mean temperature during the growing season and length of the growing season, derived from a thermal time model. Stem sapwood of cored trees was analysed for non-structural carbohydrate concentrations., The frequency of negative event years (exceptionally narrow tree rings) did not significantly increase with elevation except for Fagus sylvatica. Late season non-structural carbohydrate concentrations remained at a high level across elevations in all species, suggesting that trees are not carbon-limited at their high-elevation limit., Annual BAI showed no significant change over a wide range of elevations, before it gradually decreased over the last few hundred (300-500) metres below the range limit, with an abrupt decrease in few species at the range limit. Annual BAI correlated with the mean temperature during the growing season in the uppermost 400 m of elevation. The length of the growing season had only a significant effect on BAI at warm mean temperatures during the growing season (i.e. at lower elevation or during warmest summers)., Synthesis. While temperature has a strong effect on wood formation, the length of the growing season is negligible for stem growth at high elevation due to the low rate of wood formation at low temperature and the over-proportional increase of growth with warmer temperatures. We ruled out a direct growth limitation by low temperature as the limiting factor of the upper distribution limits and rather suggest that the formation of range limits (not necessary the rate of growth) is set by a minimum requirement of warmth and season length to fully mature key tissues such as seeds, shoots or winter hardy buds. [ABSTRACT FROM AUTHOR]

Ski tourism is strongly influenced by climate change. The economic success of ski tourism regions depends on both the quantity and quality of the ski resorts' opening days. However, to date there has been little research on the quality of ski season opening days. The purpose of this paper is to develop and apply a parameter that enables us to assess the future development of ski seasons in a differentiated way. The results show a decrease of ski area opening days from 2011 to 2060 in the investigation area in general and a trend to an intra-seasonal postponing of optimal ski days, labelled the 'Christmas-Easter shift'. The parameter developed contributes to our understand-ing of climate change effects on the tourism supply-side at a regional scale and offers decision support to ski lift operators or tourism associations in terms of adaptation measures. [ABSTRACT FROM AUTHOR]

The rapidly warming temperatures in high-latitude and alpine regions have the potential to alter the phenology of Arctic and alpine plants, affecting processes ranging from food webs to ecosystem trace gas fluxes. The International Tundra Experiment (ITEX) was initiated in 1990 to evaluate the effects of expected rapid changes in temperature on tundra plant phenology, growth and community changes using experimental warming. Here, we used the ITEX control data to test the phenological responses to background temperature variation across sites spanning latitudinal and moisture gradients. The dataset overall did not show an advance in phenology; instead, temperature variability during the years sampled and an absence of warming at some sites resulted in mixed responses. Phenological transitions of high Arctic plants clearly occurred at lower heat sum thresholds than those of low Arctic and alpine plants. However, sensitivity to temperature change was similar among plants from the different climate zones. Plants of different communities and growth forms differed for some phenological responses. Heat sums associated with flowering and greening appear to have increased over time. These results point to a complex suite of changes in plant communities and ecosystem function in high latitudes and elevations as the climate warms. [ABSTRACT FROM AUTHOR]

The thermal melanin hypothesis posits that ectothermic individuals of larger size or from colder environments exhibit darker cuticles due to melanin's efficacy in absorbing solar radiation. However, melanin is also a crucial component of arthropod immunity. Thus, thermal selection for increased cuticle darkness may profoundly influence melanin-based immune function. In this study, we address the relationships between the thermal environment (season length), cuticular melanism and two aspects of melanin-based immunity across nine thermally distinct populations of the cricket Allonemobius socius. We found that season length (i.e. degree days) and body size had a positive association with cuticle melanism in both sexes across populations, supporting the thermal melanism hypothesis. Despite their smaller size, males were found to have darker cuticles and superior melanin-based immunity. This pattern may be the result of additional selection on males due to sex-specific temperature-dependent activities, such as male calling song. Perhaps most interestingly, we found that short season length populations (i.e. colder) exhibited a greater phenoloxidase activity (aspect of the melanin-based immune system) in addition to darker cuticles in both sexes. This pattern is consistent with direct thermal selection on cuticular color, coupled with indirect selection on melanin-based immunity due to pleiotropy. Thus, thermal selection on cuticle darkness appears to indirectly shape the evolution of pathogen resistance in this system, and potentially for other terrestrial arthropod systems whose ranges encompass a significant thermal gradient. [ABSTRACT FROM AUTHOR]

Body size of insects with flexible life cycles is expected to conform to the saw-tooth model, a model in which the relationship between size and developmental time depends on length of the growing season. In species with high variability in terms of voltinism, however, more complex patterns can be expected. Few empirical studies have demonstrated the existence of such relationships, or whether climatic factors contribute to these relationships. In this study, we investigated the geographic variation in body size of the Chinese cockroach, Eupolyphaga sinensis Walker ( Blattaria: Polyphagidae), which has a variable life cycle length. The sizes of adults - collected from 14 localities ranging from temperate to subtropical zones in China - were measured, using body length, body width, and pronotum width as parameters. The relationship between size, latitude, and climate factors (encompassing 10 variables) was then investigated. We found that the body size of E. sinensis varied considerably with latitude: cockroaches were larger at low and high latitudes, but smaller at intermediate latitudes. Thus, the relationship between climate and body size conformed to a saw-tooth pattern. Results indicate that two factors were significantly associated with body size clines: season length and variability in life cycle length. Our results also demonstrated that climatic factors contribute to latitudinal clines in body size, which has important ecological and evolutionary implications. It can be expected that global climate change may alter latitudinal clines in body size of E. sinensis. [ABSTRACT FROM AUTHOR]

Background: Many arctic and alpine plant species from cold environments reproduce mainly vegetatively and can be extremely long-lived. To understand the life history and population dynamics of such species, careful in-situ measurements of growth are essential, but reports of such measurements are still scarce. Aims: Our objectives were to compare annual horizontal growth in populations of five clonal arctic-alpine species in different geographic regions, successional stages and years, and to test how much their mean annual growth is affected by season length. Methods: We performed replicated measurements of annual size increments in 36 populations of Carex curvula, Dryas octopetala, Salix herbacea, Vaccinium uliginosum and Empetrum nigrum in three arctic-alpine regions of Europe for 2 years (2008–2010). Results: The mean annual horizontal growth was different among the species and between early and late successional stages in both years. In late successional populations, the mean growth over both years was between 0.46 mm (Carex curvula) and 13.2 mm (Empetrum nigrum), and in early successional populations, the growth was between 0.85 mm and 19.0 mm, respectively. Across geographical regions, growth rates were not different, despite a difference of as much as 50 days among season lengths. Conclusions: Our results indicate that horizontal growth in arctic-alpine clonal plants may not be strongly affected by a warmer climate in the future. As a consequence, changes in arctic-alpine late successional vegetation dominated by the clonal species studied here might be slower in the face of global warming than changes in other vegetation types. [ABSTRACT FROM PUBLISHER]

The article presents a study to determine the ability of atmosphere and ocean general circulating models (AOGCMs) to simulate season lengths in the U.S. It evaluates the regional-scale correction factors' effectiveness to improve its accuracy. The study finds that the accuracy of simulated season lengths and the effectiveness of the correction factors varies geographically. It suggests an evaluation of the effectiveness of the correction factors in studies of global climate change.

Recent trends in seasonal cycles in China are analyzed, based on a homogenized dataset of daily temperatures at 541 stations during the period 1960-2008. Several indices are defined for describing the key features of a seasonal cycle, including local winter/summer (LW/LS) periods and local spring/autumn phase (LSP/LAP). The Ensemble Empirical Mode Decomposition method is applied to determine the indices for each year. The LW period was found to have shortened by 2-6 d (10 yr), mainly due to an earlier end to winter conditions, with the LW mean temperature having increased by 0.2°C-0.4°C (10 yr), over almost all of China. Records of the most severe climate extremes changed less than more typical winter conditions did. The LS period was found to have lengthened by 2-4 d (10 yr), due to progressively earlier onsets and delayed end dates of the locally defined hot period. The LS mean temperature increased by 0.1°C-0.2°C (10 yr) in most of China, except for a region in southern China centered on the mid-lower reaches of the Yangtze River. In contrast to the winter cases, the warming trend in summer was more prominent in the most extreme records than in those of more typical summer conditions. The LSP was found to have advanced significantly by about 2 d (10 yr) in most of China. Changes in the autumn phase were less prominent. Relatively rapid changes happened in the 1980s for most of the regional mean indices dealing with winter and in the 1990s for those dealing with summer. [ABSTRACT FROM AUTHOR]

We developed a method for predicting wood duck (Aix sponsa) harvest rates in eastern North America using waterfowl banding and recovery data, annual indices of hunter numbers, and harvest survey data from the United States and Canada. We predicted that under the current season length (60 days), if hunter numbers remain unchanged, increasing the wood duck bag limit from 2 to 3 would increase harvest of adult male wood ducks in the Atlantic and Mississippi flyways by 12.3%, causing an increase in harvest rate of 7.1% from 0.087 to 0.093. The Flyway Councils and the United States Fish and Wildlife Service can consider this information to predict the impacts of regulatory changes. [ABSTRACT FROM AUTHOR]

Aim To measure latitude-related body size variation in field-collected Paropsis atomaria Olivier (Coleoptera: Chrysomelidae) individuals and to conduct common-garden experiments to determine whether such variation is due to phenotypic plasticity or local adaptation. Location Four collection sites from the east coast of Australia were selected for our present field collections: Canberra (latitude 35°19′ S), Bangalow (latitude 28°43′ S), Beerburrum (latitude 26°58′ S) and Lowmead (latitude 24°29′ S). Museum specimens collected over the past 100 years and covering the same geographical area as the present field collections came from one state, one national and one private collection. Methods Body size (pronotum width) was measured for 118 field-collected beetles and 302 specimens from collections. We then reared larvae from the latitudinal extremes (Canberra and Lowmead) to determine whether the size cline was the result of phenotypic plasticity or evolved differences (= local adaptation) between sites. Results Beetles decreased in size with increasing latitude, representing a converse Bergmann cline. A decrease in developmental temperature produced larger adults for both Lowmead (low latitude) and Canberra (high latitude) individuals, and those from Lowmead were larger than those from Canberra when reared under identical conditions. Main conclusions The converse Bergmann cline in P. atomaria is likely to be the result of local adaptation to season length. [ABSTRACT FROM AUTHOR]

Studies of cyclic microtine populations (voles and lemmings) have suggested a relationship between the previous year's population density and the subsequent timing of the onset of reproduction by overwintered breeding females. No studies have explored the importance of this relationship in the generation of population cycles. Here we mathematically examine the implications of variation in reproductive season length caused by delayed density-dependent changes in its start date. We demonstrate that when reproductive season length is a function of past population densities, it is possible to get realistic population cycles without invoking any changes in birth rates or survival. When parameterized for field voles (Microtus agrestis) in Kielder Forest (northern England), our most realistic model predicts population cycles of similar periodicity to the Kielder populations. Our study highlights the potential importance of density-dependent reproductive timing in microtine population cycles and calls for investigations into the mechanism(s) underlying this phenomenon. [ABSTRACT FROM AUTHOR]

Differences in the seasonal pattern of assimilatory and respiratory processes are responsible for divergences in seasonal net carbon exchange among ecosystems. Using FLUXNET data (http://www.eosdis.ornl.gov/FLUXNET) we have analyzed seasonal patterns of gross primary productivity (FGPP), and ecosystem respiration (FRE) of boreal and temperate, deciduous and coniferous forests, Mediterranean evergreen systems, a rainforest, temperate grasslands, and C3 and C4 crops. Based on generalized seasonal patterns classifications of ecosystems into vegetation functional types can be evaluated for use in global productivity and climate change models. The results of this study contribute to our understanding of respiratory costs of assimilated carbon in various ecosystems.Seasonal variability of FGPP and FRE of the investigated sites increased in the order tropical. Together with the boreal forest sites, the managed grasslands and crops show the largest seasonal variability. In the temperate coniferous forests, seasonal patterns of FGPP and FRE are in phase, in the temperate deciduous and boreal coniferous forests FRE was delayed compared to FGPP, resulting in the greatest imbalance between respiratory and assimilatory fluxes early in the growing season.FGPP adjusted for the length of the carbon uptake period decreased at the sampling sites across functional types in the order C4 crops, temperate and boreal deciduous forests (7.5–8.3 g C m−2 per day)>temperate conifers, C3 grassland and crops (5.7–6.9 g C m−2 per day)>boreal conifers (4.6 g C m−2 per day). Annual FGPP and net ecosystem productivity (FNEP) decreased across climate zones in the order tropical>temperate>boreal. However, the decrease in FNEP with latitude was greater than the decrease in FGPP, indicating a larger contribution of respiratory (especially heterotrophic) processes in boreal systems. [Copyright &y& Elsevier]