Boreal Climate Research Articles

The Relationship Between Maturation Size and Maximum Tree Size From Tropical to Boreal Climates.

The fundamental trade-off between current and future reproduction has long been considered to result in a tendency for species that can grow large to begin reproduction at a larger size. Due to the prolonged time required to reach maturity, estimates of tree maturation size remain very rare and we lack a global view on the generality and the shape of this trade-off. Using seed production from five continents, we estimate tree maturation sizes for 486 tree species spanning tropical to boreal climates. Results show that a species' maturation size increases with maximum size, but in a non-proportional way: the largest species begin reproduction at smaller sizes than would be expected if maturation were simply proportional to maximum size. Furthermore, the decrease in relative maturation size is steepest in cold climates. These findings on maturation size drivers are key to accurately represent forests' responses to disturbance and climate change.

Low nitrous oxide fluxes from mineral affected peatland soils in Iceland

Nitrous oxide (N2O) is a potent greenhouse gas, and soil is one of its most substantial sources. Emissions are influenced by both biotic and abiotic processes, as well as the physiochemical properties of the medium. Organic soils fully drained in boreal climates are a potentially significant source of nitrous oxide. Lower, drainage levels and nutrient availability have been shown to reduce N2O emissions. Predicting N2O emissions from agriculturally managed peatlands is challenging. In situ measurements are crucial for addressing these difficulties. This study presents three years of in situ field measurements of nitrous oxide fluxes and soil hydrological status in peatland soils under different agricultural management regimes: cultivated drained (CD), uncultivated drained (UCD), and wet (W) in Western Iceland. Fluxes were quantified by analysing a time-concentration series obtained from permanent chambers and subsequently evaluated using gas chromatography in the laboratory. The minimum potential N2O consumption rate (mean ± 95 % Cl) was estimated as 0.76 ± 0.38, 0.56 ± 0.18 and 0.56 ± 0.14 mg N2O-N m⁻² day⁻¹ for CD, UCD, and W sites, respectively. Yearly accumulated emissions were estimated as 2.24 ± 1.47, 1.26 ± 0.64 and 0.26 ± 0.44 kg N2O-N ha−1 yr−1 for CD, UCD, and W sites, respectively. The relatively low emission rates observed at drained sites can be explained by the stable water content, and by limited availability of soil phosphorus, which hampers N2O production and potentially leads to more active N2O consumption. Both the stable water content and low phosphorus availability is explained by mineral inputs to the peatlands, acting through decreased soil unsaturated hydraulic conductivity and increased phosphorus retention. The effects of mineral content offer potential mitigation option to decrease N2O emissions. This study highlights the complexity of N2O emissions from peatland soils and emphasizes the significance of site-specific factors in managing greenhouse gas emissions. Further studies investigating the underlying processes behind N2O fluxes in the peatland and andic soils are recommended.

Maskwio’mi (Birch Bark Extract): A Case Study Exploring The Use Of A Traditional L’nu Medicine On Skin Conditions

According to the Canadian Dermatology Association, more than 1 in 4 Canadians live with chronic skin conditions. There are many different treatment options, including prescription medications, over-the-counter drugs, natural remedies, and herbal folk medicines. Folk medicines have a long history, and birch trees (genus betula) have shown great utility for treating skin conditions in societies of temperate and boreal climate zones and have been listed in pharmacopoeias for several centuries. Maskwio’mi (maskwi = birch, o’mi = gathering or oil) is such a traditional skin remedy from the L’nu (Mi’kmaq) people of Atlantic Canada. This case study is part of a larger study and the first to document usage of maskwio’mi for skin conditions, with a goal of future in-depth clinical studies and hopes of recognizing it as a natural health product.

Why we thrive beneath a northern sky – genomic signals of selection in apple for adaptation to northern Sweden

Good understanding of the genomic regions underlying adaptation of apple to boreal climates is needed to facilitate efficient breeding of locally adapted apple cultivars. Proper infrastructure for phenotyping and evaluation is essential for identification of traits responsible for adaptation, and dissection of their genetic composition. However, such infrastructure is costly and currently not available for the boreal zone of northern Sweden. Therefore, we used historical pomological data on climate adaptation of 59 apple cultivars and whole genome sequencing to identify genomic regions that have undergone historical selection among apple cultivars recommended for cultivation in northern Sweden. We found the apple collection to be composed of two ancestral groups that are largely concordant with the grouping into ‘hardy’ and ‘not hardy’ cultivars based on the pomological literature. Using a number of genome-wide scans for signals of selection, we obtained strong evidence of positive selection at a genomic region around 29 MbHFTH1 of chromosome 1 among apple cultivars in the ‘hardy’ group. Using phased genotypic data from the 20 K apple Infinium® SNP array, we identified haplotypes associated with the two cultivar groups and traced transmission of these haplotypes through the pedigrees of some apple cultivars. This demonstrates that historical data from pomological literature can be analyzed by population genomic approaches as a step towards revealing the genomic control of a key property for a horticultural niche market. Such knowledge is needed to facilitate efficient breeding strategies for development of locally adapted apple cultivars in the future. The current study illustrates the response to a very strong selective pressure imposed on tree crops by climatic factors, and the importance of genetic research on this topic and feasibility of breeding efforts in the light of the ongoing climate change.

Multidimensional trait space outlines the effects of changes in abiotic filtering on aquatic plant community from sub-Antarctic ponds

In the current context of climate changes, which causes strong habitat variation, an understanding of the mechanisms underlying plant community dynamics is crucial to predict species fates. The taking of inter- and intraspecific trait variability into account would aid the identification of these mechanisms. Recently, a method involving the calculation of hypervolumes (n-dimensional spaces of trait values) was developed for the study of plant responses to their environments. Through hypervolume comparison, we examined the effects of interannual variations in abiotic conditions on aquatic plant communities in ponds of the sub-Antarctic Iles Kerguelen. This model system is particularly relevant for the examination of the consequences of climate changes–related habitat variation, as aquatic plant communities are adapted to cold and overall stable habitat conditions and the sub-Antarctic climate is changing rapidly. We conducted field sampling over four years at three sites. For all aquatic species, we measured five foliar, shoot, and clonal traits characterizing individual growth strategies that are likely to respond to variations in abiotic conditions on 1565 ramets over the four years. We measured 10 abiotic variables to characterize the plants’ habitats every three months during the survey period. Hypervolumes were calculated for each site and year to assess variation in aquatic plant strategies at the community level. We demonstrated (i) the importance of spatiotemporal gradients of trophic status, temperature, and pH and dissolved oxygen concentration for the functional structure of aquatic plant communities; (ii) that the shape of the mean response was trait dependent, with traits related to plant metabolism (specific leaf area and specific internode mass) and three-dimensional space exploration (height and internode length) responding to the three spatiotemporal abiotic gradients; (iii) that selection pressures were especially high on aerial traits relative to clonal traits; and (iv) that given the community response to interannual variations of abiotic conditions, environmental changes should impact macrophyte community productivity. Synthesis. We conclude that the examination of interannual abiotic variation over four years is sufficient to detect rapid responses of macrophyte communities, with likely reliance on phenotypic plasticity. Our findings may inform the characterization of future functional changes in aquatic plant communities of the sub-Antarctic region, where similar species are found.

Cover crops affect pool specific soil organic carbon in cropland – A meta‐analysis

AbstractCover crops (CC) offer numerous benefits to agroecosystems, particularly in the realm of soil organic carbon (SOC) accrual and loss mitigation. However, uncertainties persist regarding the extent to which CCs, in co‐occurrence with environmental factors, influence SOC responses and associated C pools. We therefore performed a weighted meta‐analysis on the effects of CCs on the mineral‐associated organic carbon (MAOC), the particulate organic carbon (POC) and the microbial biomass carbon (MBC) pool compared to no CC cultivation in arable cropland. Our study summarized global research of comparable management, with a focus on climatic zones representative of Europe, such as arid, temperate and boreal climates. In this meta‐analysis, we included 71 independent studies from 61 articles published between 1990 and June 2023 in several scientific and grey literature databases. Sensitivity analysis was conducted and did not identify any significant publication bias. The results revealed that CCs had an overall statistically significant positive effect on SOC pools, increasing MAOC by 4.8% (95% CI: 0.6%–9.4%, n = 16), POC by 23.2% (95% CI: 13.9%–34.4%, n = 39) and MBC by 20.2% (95% CI: 11.7%–30.7%, n = 30) in the top soil, compared to no CC cultivation. Thereby, CCs feed into the stable as well as the more labile C pools. The effect of CCs on MAOC was dependent on soil clay content and initial SOC concentration, whereas POC was influenced by moderators such as CC peak biomass and experiment duration. For MBC, for example, clay content, crop rotation duration and tillage depth were identified as important drivers. Based on our results on the effects of CCs on SOC pools and significant moderators, we identified several research needs. A pressing need for additional experiments exploring the effects of CCs on SOC pools was found, with a particular focus on MAOC and POC. Further, we emphasize the necessity for conducting European studies spanning the north–south gradient. In conclusion, our results show that CC cultivation is a key strategy to promote C accrual in different SOC pools. Additionally, this meta‐analysis provides new insights into the state of knowledge regarding SOC pool changes influenced by CCs, offering quantitative summary results and shedding light on the sources of heterogeneity affecting these findings.

Global burden study of lower respiratory infections linked to low temperatures: an analysis from 1990 to 2019.

Low temperature conditions have been linked to a heightened susceptibility to lower respiratory infections (LRIs). Yet, our comprehension of the LRIs' disease burden due to such conditions remains limited, especially when considering the diverse socio-demographic indexes (SDIs) and climate types across various nations and regions. We examined the variations over time and space in the impact of LRIs due to low temperatures across a diverse set of 204 nations and regions, each with unique SDIs and climate types, spanning the years 1990 to 2019. Data from the Global Burden of Disease Study 2019 was used for this retrospective analysis. The burden of LRIs attributable to low temperatures was estimated by stratifying by sex, age, country, climate type, and SDI, including age-standardized mortality rate (ASMR) and age-standardized disability-adjusted life year rate (ASDR). We employed Joinpoint models to compute the annual average percent changes (AAPCs) in order to evaluate the trends in LRIs burden due to low temperatures from 1990 to 2019. Furthermore, we utilized Poisson age-period-cohort models to forecast the global and income-specific trends in LRIs burden due to low temperatures for the period 2020-2044. Generalized additive mixed models were used to fit changes in the disease burden of different climate regions. The relationship between SDI and both ASMR and ASDR was determined using models grounded in Gaussian process regression. In general, since the year 1990, there has been a significant reduction in the worldwide impact of LRIs due to low temperatures. This decrease is particularly noticeable among infants and the elderly, as well as in regions with a boreal climate and those with an average SDI. In 2019, LRIs induced by low temperatures showed an ASMR of 2.2 (95% CI: 1.34, 3.07) and an ASDR of 53.73 (95% CI: 17.5, 93.22) for every 100,000 individuals. A global reduction was observed in the ASMR and ASDR for LRIs over the period from 1990 to 2019, showing a decrease of 60.27% and 77.5%, in that order. For ASMR and ASDR, the AAPC values were found to be - 3.3 (95% CI: - 3.4, - 3.1) and - 5 (95% CI: - 5.2, - 4.9), in that order. However, a contrasting pattern was observed in southern Latin America, where an increase was noted in the ASMR for LRIs induced by low temperatures [AAPC: 0.5; 95% CI: (0.3, 0.8)]. Low temperature has decreased as an environmental risk factor for LRIs globally over 30years, especially in middle SDI regions and boreal climates, but remains important for infants and the elderly population.

Which temperature matters? Effects of origin, rearing and test conditions on the chemical sensitivity of Pardosa amentata

AbstractSpiders may be adversely affected by pesticides, yet they are not included in regulatory risk assessment and a related standard guideline to test their sensitivity to chemicals is lacking. Different laboratory setups, including test temperature and relative humidity, have been shown to influence the sensitivity of spiders. The climate from which spiders originate and the rearing conditions in the laboratory prior to ecotoxicological testing may also alter their sensitivity to chemicals, potentially in interaction with test conditions. We investigated the influence of population origin, rearing and test temperature on the chemical sensitivity of the spider Pardosa amentata towards lambda‐cyhalothrin. We collected female P. amentata carrying egg sacs from two climates, i.e., boreal and cool temperate. Spiders were kept in the laboratory and their offspring were reared and tested at 15, 20 and 25°C. Hatching of egg sacs largely failed at 15°C, while a moderate spiderling mortality (40%) was recorded at 20°C. At 25°C, mortality increased (63%) and a faster developmental rate was observed. Rearing and test temperature had no significant effects on spider chemical sensitivity. However, spider chemical sensitivity differed between populations, with spiders from boreal climate being 38% more sensitive than spiders from cool temperate climate. A higher sensitivity towards lambda‐cyhalothrin increases the risk of population reduction in treated areas, with potential alterations of ecosystem functions such as biological control. Our results suggest that the climatic origin of test organisms deserves stronger attention in ecotoxicological research.

The interior spreading story of Labrador Sea Water

The unique convective anomalies of Labrador Sea Water (LSW) can be used as advective tracers when assessing equatorward spreading pathways and timescales of LSW. In this study, we explore advective pathways of two LSW classes formed in the 1990s and early 2000s, respectively, along constant neutral density planes. Hydrographic observations showcase the prevalence of both LSW classes within the Atlantic interior, supporting a recirculation feature that branches from the Deep Western Boundary Current (DWBC) at 36°N among other pathways. Spreading characteristics of both LSW classes from the Labrador Sea to the subtropics are reinforced through a spatial pattern analysis of salinity anomalies and geostrophic velocities along the characteristic neutral density planes of each respective LSW class. We observe both classes to advect out of the Labrador Sea to (i) the eastern subpolar region and down the eastern boundary towards the Atlantic interior, (ii) directly into the Atlantic interior likely from an injection by recirculations from the subpolar gyre and DWBC leakage, and (iii) equatorward along the western boundary via the DWBC. Findings highlight the abundance of LSW within the Atlantic interior, not just along the western boundary, suggesting that interior pathways play an influential role on the export of these subpolar climate signals.

Fungal colonisation on wood surfaces weathered at diverse climatic conditions

Natural weathering test at two different European climatic zones were conducted to investigate simultaneously both, the fungal colonisation and weathering process of Scots pine wood (Pinus sylvestris L.). The hypothesis was that the wood performing differently in various climate conditions might affect fungal infestation. The colour changes, wettability, and glossiness were measured as indicators of weathering progress of wood together with an assessment of fungal diversity. Different intensities in weathering, occupancy, and colonisation of fungi on wooden surface were detected. A higher number of fungal species was found on wood exposed to the warm temperate climates compared to subarctic or boreal climates. The dominant fungal species in both locations were from the genera Cladosporium and Aureobasidium.

Climate warming causes photobiont degradation and carbon starvation in a boreal climate sentinel lichen.

The long-term potential for acclimation by lichens to changing climates is poorly known, despite their prominent roles in forested ecosystems. Although often considered "extremophiles," lichens may not readily acclimate to novel climates well beyond historical norms. In a previous study (Smith et al., 2018), Evernia mesomorpha transplants in a whole-ecosystem climate change experiment showed drastic mass loss after 1 yr of warming and drying; however, the causes of this mass loss were not addressed. We examined the causes of this warming-induced mass loss by measuring physiological, functional, and reproductive attributes of lichen transplants. Severe loss of mass and physiological function occurred above +2°C of experimental warming. Loss of algal symbionts ("bleaching") and turnover in algal community compositions increased with temperature and were the clearest impacts of experimental warming. Enhanced CO2 had no significant physiological or symbiont composition effects. The functional loss of algal photobionts led to significant loss of mass and specific thallus mass (STM), which in turn reduced water-holding capacity (WHC). Although algal genotypes remained detectable in thalli exposed to higher stress, within-thallus photobiont communities shifted in composition toward greater diversity. The strong negative impacts of warming and/or lower humidity on Evernia mesomorpha were driven by a loss of photobiont activity. Analogous to the effects of climate change on corals, the balance of symbiont carbon metabolism in lichens is central to their resilience to changing conditions.

Modeled storm surge changes in a warmer world: the Last Interglacial

Abstract. The Last Interglacial (LIG; ca. 125 ka) is a period of interest for climate research as it is the most recent period of the Earth's history when the boreal climate was warmer than at present. Previous research, based on models and geological evidence, suggests that the LIG may have featured enhanced patterns of ocean storminess, but this remains hotly debated. Here, we apply state-of-the-art climate and hydrodynamic modeling to simulate changes in sea level extremes caused by storm surges, under LIG and pre-industrial climate forcings. Significantly higher seasonal LIG sea level extremes emerge for coastlines along northern Australia, the Indonesian archipelago, much of northern and eastern Africa, the Mediterranean Sea, the Gulf of Saint Lawrence, the Arabian Sea, the east coast of North America, and islands of the Pacific Ocean and of the Caribbean. Lower seasonal LIG sea level extremes emerge for coastlines along the North Sea, the Bay of Bengal, China, Vietnam, and parts of Central America. Most of these anomalies are associated with anomalies in seasonal sea level pressure minima and in eddy kinetic energy calculated from near-surface wind fields, and therefore seem to originate from anomalies in the meridional position and intensity of the predominant wind bands. In a qualitative comparison, LIG sea level extremes seem generally higher than those projected for future warmer climates. These results help to constrain the interpretation of coastal archives of LIG sea level indicators.

No risk—no fun: Penalty and recovery from spring frost damage in deciduous temperate trees

Abstract Phenological shifts in response to changing climatic conditions is a key acclimation process for the persistence of perennial plants in temperate and boreal climates. The optimal time to leaf‐out is the result of an evolutionary process determined by the trade‐off between minimizing the risk of freezing damages and herbivory pressure while maximizing resource uptake to increase competitiveness against the other plants. We quantified the penalty exerted by frost damage at the time of leaf emergence on plant development (reduction in leaf area, canopy duration and growth) over the potential gains without frost (increased biomass and non‐structural carbohydrate reserves), depending on when leaf‐out occurs. To this purpose, we exposed 960 saplings of four temperate deciduous tree species with contrasting cold hardiness to two frost intensities shortly after leaf emergence, which was artificially induced at four occasions to reflect the whole range of natural leaf‐out dates. One year above‐ground biomass (AGB) increments following the frost revealed a clear ranking among the species depending on their strategy to cope with damaging frosts. Prunus avium (−41% of AGB‐increment compared to control saplings) resprouted from the stem base, Quercus robur (−62%) rapidly produced new leaves from dormant reserve buds, Fagus sylvatica (−98%) showed highest chlorophyll content in autumn and delayed senescence together with Carpinus betulus (−105%), which overcompensated NSC reserves after the growing season but showed highest mortality (up to 32%). In all species, NSC reserves recovered rapidly to control levels at the expense of growth. The timing of leaf‐out (advanced and delayed artificially) significantly affected the performance and recovery (regreening and growth) of both frozen and non‐frozen saplings, with the lowest performance found at the most delayed leaf‐out date. We propose that the potential to recover from frost damages is an important component of a tree's performance, particularly at the juvenile stage. The ability to recover may become even more decisive in the future with the predicted increase of false springs in many extratropical regions. Read the free Plain Language Summary for this article on the Journal blog.

Recent and future hydrological trends of aapa mires across the boreal climate gradient

Aapa mires are boreal peatland complexes comprised of wet, typically patterned fens in the center and Sphagnum bog vegetation at the margins. Their distribution is controlled by climate and local catchment hydrology. The daily discharge of twelve aapa mires across the boreal zone was explored for 1961–2099, with the CPIsnow model using observational weather data and projections based on climate models (CMIP5) and emission scenarios (RCP4.5 and RCP8.5). Mire hydrology was assessed for climate-zonal differences, seasonal patterns, and longer-term trends. The results indicated past and future changes in hydrology, particularly related to the duration and magnitude of snow cover and the timing of snowmelt. Increasing winter discharge and decreasing spring discharge were detected in recent past in the southern sites, and these trends were indicated to continue in the future throughout the study area. By the end of the 21st century, the typical seasonality of discharge is indicated to weaken throughout the study area and to largely disappear in the south boreal catchments. In the northernmost sites, a mismatch between past trends and future projections of spring discharge was discovered, indicating complexity and uncertainty of snow process modeling. The hydrological changes indicated in this study, together with direct impacts of increasing temperatures, threaten aapa mires, affecting biodiversity and greenhouse gas balance. In changing climate, special attention should be paid to winter conditions and snow, essential for the hydrological cycle in the north but under-explored in mire hydrology studies.

Mechanical scarification can reduce competitive traits of boreal ericaceous shrubs and improve nutritional site quality

Abstract Ericaceous shrubs often interfere with the growth of black spruce seedlings on regenerating forest sites in Eastern Canada. Mechanical site preparation such as scarification may improve this situation, but it is uncertain whether this is solely due to a reduction in direct competition from the shrubs, or also from a sustained improvement in nutritional site quality. We sampled experimental plots in two boreal climate regions (i.e. warmer-drier Abitibi vs. cooler-wetter Côte-Nord) where scarification, performed 18 years earlier, had increased the growth of black spruce relative to non-scarified plots. Trees of scarified plots had closed the canopy more than trees of non-scarified plots in Côte-Nord, but not in Abitibi. Total ground cover of ericaceous shrubs was lower in scarified plots at both sites, the main species being Kalmia angustifolia (i.e. Kalmia) in Abitibi and Rhododendron groenlandicum (i.e. Labrador tea) in Côte-Nord. Scarified plots at both sites had significantly shorter current-year ericaceous rhizomes than non-scarified plots, but the difference between treatments was significantly greater in Côte-Nord than in Abitibi. In Côte-Nord, ericaceous shrubs on scarified plots had a lower specific rhizome mass, higher specific leaf area, lower tannin and higher N concentrations in leaves and litter, and lower N use efficiency than on non-scarified plots. By comparison, scarification in Abitibi affected only one foliar property, namely a reduction in the C:N ratio of Kalmia leaf litter. Forest floor N mineralization rates and black spruce needle N concentrations were higher in scarified than non-scarified plots across both sites. Taken collectively, results suggest that mechanical scarification on ericaceous shrub-dominated cutovers can reduce competitive traits of boreal ericaceous shrubs and improve nutritional site quality, especially in cooler-wetter climates.Highlights

Cost-effective and environmentally friendly solar collector for thermally driven cooling systems

Solar collectors are key components that allow the exploitation of solar radiation in sustainable applications such as solar cooling systems. However, the selection criteria of the suitable technology of solar collector are still ambiguous. This paper presents a comprehensive investigation of absorption and adsorption cooling systems powered by different solar collectors, namely flat plate collector, evacuated-tube collector, compound parabolic collector, parabolic trough collector, photovoltaic thermal collector and a new configuration of concentrating photovoltaic thermal collector, for air-conditioning application in a residential building. Thus, the impact of each solar collector on thermal, economic and environmental performances of the solar cooling systems is quantified to identify the most cost-effective and eco-friendly system, under three different climate conditions. The performance results showed that the proposed concentrating photovoltaic thermal collector performed the best for absorption cooling system with a solar coefficient of performance of 0.449, 0.428 and 0.414 in Marrakesh, Barcelona and Oslo cities, characterized by hot arid, warm temperate and boreal climates, respectively, and for the adsorption cooling system as well in Oslo city with a solar coefficient of performance of 0.351, while photovoltaic thermal collector exhibited the best performance for adsorption cooling system in Marrakesh and Barcelona cities with a solar coefficient of performance of 0.397 and 0.386, respectively. Furthermore, the economic findings revealed that the photovoltaic thermal collector is the most cost-effective one for absorption/adsorption systems, with levelized cost of cooling in the order of €0.106/0.111, €0.137/0.142 and €0.287/0.313 per kWh, and discounted payback period of 11.25/11.43, 15.23/14.94 and 24/25.63 years in Marrakesh, Barcelona and Oslo cities, respectively. Besides, evacuated-tube collector is found to be the most environmentally-friendly collector, since it allows reducing greenhouse gases emissions especially in boreal climate with a life cycle climate performance of 5.86/5.99 tCO2 for absorption/adsorption systems.

Landscape and climate conditions influence the hydrological sensitivity to climate change in eastern Canada

Hydrological conditions in cold regions have been shown to be sensitive to climate change. However, a detailed understanding of how regional climate and basin landscape conditions independently influence the current hydrology and its climate sensitivity is currently lacking. This study, therefore, compares the climate sensitivity of the hydrology of two basins with contrasted landscape and meteorological characteristics typical of eastern Canada: a forested boreal climate basin (Montmorency) versus an agricultural hemiboreal climate basin (Acadie). The physically based Cold Regions Hydrological Modelling (CRHM) platform was used to simulate the current and future hydrological processes. Both basin landscape and regional climate drove differences in hydrological sensitivities to climate change. Projected peak SWE were highly sensitive to warming, particularly for milder baseline climate conditions and moderately influenced by differences in landscape conditions. Landscape conditions mediated a wide range of differing hydrological processes and streamflow responses to climate change. The effective precipitation was more sensitive to warming in the forested basin than in the agricultural one, due to reductions in forest canopy interception losses with warming. Under present climate, precipitation and discharge were found to be more synchronized in the greater relief and slopes of the forested basin, whereas under climate change, they are more synchronized in the agricultural basin due to reduced infiltration and storage capacities. Flow through and over agricultural soils translated the increase in water availability under a warmer and wetter climate into higher peak discharges, whereas the porous forest soils dampened the response of peak discharge to increased available water. These findings help diagnose the mechanisms controlling hydrological response to climate change in cold regions forested and agricultural basins.

Обоснование статистической модели для описания и прогноза рисков населения подвергнуться атакам иксодовых клещей

Incidence of tick-borne encephalitis and other tick-borne infections correlates with a number of people applying for medical aid due to tick bites. Obviously, the number of registered tick bites is proportionate to people’s economic and recreational activities on an endemic territory and the quantity of hungry ticks. In its turn, the quantity of ticks depends on abundance of main hosts for blood-feeding stages but with a certain time lag caused by their life cycle parameters such as molting to the next stage, diapauses, and apparent seasonality in a continental boreal climate zone. Our research goal was to analyze and synthesize an adequate formalized/parameterized statistical model to describe and predict risks of tick bites for population. To describe dynamics and to predict a number of people bitten by ticks exemplified by the Sverdlovsk region, we used several linear (by parameters) logistic regression models. We applied a multimodel inference framework to assess whether the observed dynamics was described adequately. Long-tern dynamics of the number of people bitten by ticks in the Sverdlovsk region is characterized with an occurring high-amplitude slow long-wave oscillation (circadecadal one, with a quasi-period being approximately 10 years) and a short-wave 2–3-year cyclicity. The former may be associated with climatic rhythm and socioeconomic trends; the latter may be caused by biotic factors. By using the logit-regression model, we showed that the number of small mammals, both in the previous year and at the beginning of the current tick activity season can be a valuable predictor of a risk for population to be bitten by ticks. Predictive values of the created statistical model adequately describe an initial time series of chances/probabilities of tick bites.

Substantiation of statistical model to describe and predict risks of tick bites for population

Incidence of tick-borne encephalitis and other tick-borne infections correlates with a number of people applying for medical aid due to tick bites. Obviously, the number of registered tick bites is proportionate to people’s economic and recreational activities on an endemic territory and the quantity of hungry ticks. In its turn, the quantity of ticks depends on abundance of main hosts for blood-feeding stages but with a certain time lag caused by their life cycle parameters such as molting to the next stage, diapauses, and apparent seasonality in a continental boreal climate zone. Our research goal was to analyze and synthesize an adequate formalized/parameterized statistical model to describe and predict risks of tick bites for population. To describe dynamics and to predict a number of people bitten by ticks exemplified by the Sverdlovsk region, we used several linear (by parameters) logistic regression models. We applied a multimodel inference framework to assess whether the observed dynamics was described adequately. Long-tern dynamics of the number of people bitten by ticks in the Sverdlovsk region is characterized with an occurring high-amplitude slow long-wave oscillation (circadecadal one, with a quasi-period being approximately 10 years) and a short-wave 2–3-year cyclicity. The former may be associated with climatic rhythm and socioeconomic trends; the latter may be caused by biotic factors. By using the logit-regression model, we showed that the number of small mammals, both in the previous year and at the beginning of the current tick activity season can be a valuable predictor of a risk for population to be bitten by ticks. Predictive values of the created statistical model adequately describe an initial time series of chances/probabilities of tick bites.

Mineralogic controls are harbingers of hydrological controls on soil organic matter content in warmer boreal forests

Boreal forests contain ∼ 30 % of the global forest soil organic carbon (SOC) stock within a region vulnerable to climate change, yet regional studies on the climate relevant controls of this large reservoir are lacking. The Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect represents a boreal climate gradient of sites ranging in temperature and precipitation similar in extent to changes expected within the region over the next century. Though forest and soil type are similar across the transect, geological parent material upon which soils have developed vary across the region. Despite a > 50 % increase in litterfall and a 3-fold increase in the dissolved organic matter inputs to the mineral soil with decreasing latitude, average surface horizon mineral SOC and N content are similar among regions. To explain this, the relationships between mineral soil characteristics and other ecosystem parameters with SOC and N content were assessed using an information theoretic approach to rank models. Rankings were used to determine the most relevant variables explaining regional variance in surface mineral SOC. Unsurprisingly, organo-metal complexes (OMCs), a weathering product, were a major component of all plausible models. However, Al complexes ranked higher than Fe, likely because of the greater solubility of reduced Fe in reducing microsites, particularly beneath the winter snowpack or within the saturated soils during the spring melt. These results highlight the potential role of seasonal hydrology on the formation of metal-stabilized C and N in boreal forests and suggest that the role of Fe OMC in C sequestration may be enhanced with warmer winters. The realization and effect of these seasonally controlled OMC mechanisms require further understanding of mineral soil characteristics and hydrology and their response to climate warming. Such efforts will improve predictions of the impact of climate change on soil C and N content in these forests.