Winter Thaw Research Articles

Experimental exposure to winter thaws reveals tipping point in yellow birch bud mortality and phenology in the northern temperate forest of Québec, Canada

Climate change is expected to increase the frequency and intensity of winter thaws, which could affect leaf phenology. Phenology could either be advanced through the acceleration of forcing accumulation or chilling completion, or be postponed through a reduction in chilling associated with warming air temperature. We tested the influence of winter thaws on budburst phenology by exposing 300 tree cuttings of sugar maple and yellow birch trees to five different frequencies and durations of winter thaws in the lab. In spring, half of the cuttings were exposed to air temperature in two cities representing an air temperature gradient of + 2.0 °C to mimic the ongoing climate warming and bud phenology was monitored three times a week. Irrespective of thaw treatment, yellow birch bud phenology occurred earlier in the warmer city, showing the importance of spring temperature in triggering budburst. The treatment with the highest frequency and duration of thawing increased bud mortality and delayed the onset of spring budburst whereas low frequency treatments did not, thereby identifying a tipping point (3 days twice a month) in the impact of winter thaws on bud phenology. Past this point, winter thaws could slow down bud phenology induced by warmer spring temperature and limit carbon uptake by delaying the closure of the canopy. Climate change simulations projected by the CMIP6 Canadian downscaled climate scenario show that winter thaws will increase in frequency Hence the expected advance in spring leaf emergence associated with warmer spring is not necessarily as straightforward as previously thought.

Warmer future climate in Canada—implications for winter survival of perennial forage crops

Significant increase in wintertime air temperature, especially the reduced cold extremes under climate change, might be beneficial to the winter survival of perennial crops. However, climate warming could result in less snowfall, reduced snow cover, as well as changes in climate conditions for fall hardening and winter thaws. How these changes might impact the risks of winter damages to overwintering crops, such as perennial forage crops requires a comprehensive assessment for proactively adapting to climate change in the agricultural sector, especially the beef and dairy industries. Based on the most up-to-date climate projections from a set of global climate models, we used a snow model and a suite of agroclimatic indices for perennial forage crops to assess potential changes in the risks of winter injury to perennial forage crops across Canada in the near-term (2030s), the mid-term (2050s), and the distant future (2070s). Our results show that the risk of exposure to extremely low temperatures (daily Tmin ≤ −15 °C) without snow protection is projected to decrease across Canada with improved conditions for fall hardening. However, winter thaws and rainfall are projected to increase, and this would increase the risk of winter injury due to loss of hardiness together with potential soil heaving and ice encasement.

Nitrogen immobilization could link extreme winter warming events to Arctic browning

Arctic extreme winter warming events (WW events) have increased in frequency with climate change. WW events have been linked to damaged tundra vegetation (“Arctic browning”), but the mechanisms that link episodic winter thaw to plant damage in summer are not fully understood. We suggest that one mechanism is microbial N immobilization during the WW event, which leads to a smaller release of winter-mineralized N in spring and therefore more N limitation for vegetation in summer.We tested this hypothesis in a Western Greenlandic Low arctic tundra, where we experimentally simulated a 6 day field-scale extreme WW event and 1) used stable isotopes to trace the movement of N as a consequence of the WW event, 2) measured the effect of a WW event on spring N release in top soils in the laboratory, and 3) measured the carry-over effect on summer aboveground vegetation C/N ratio in tundra subject to a WW event.Our results show that soil mineral N released by a WW event followed by soil thaw is taken up by microbes and stored in the soil, whereas vascular plants acquired almost none, and significant amounts were lost to leaching and gaseous emissions. As soils thawed in spring, we saw weak but not significant evidence (P = 0.067) for a larger N release over the first month of spring thaw in Control soils compared to WW event soils, although not significantly. A weak signal (P = 0.07) linked WW event treatment to higher summer C/N ratios in evergreen shrubs, whereas deciduous shrubs were not affected.We conclude that our results did not show significant evidence for WW events causing Arctic browning via N immobilization and summer N limitation, but that we had indications (P < 0.1) which merits further testing of the theory in various tundra types and with repeated WW events. Evergreen shrubs could be especially sensitive to winter N immobilization, with implications for future vegetation community composition and tundra C storage.

Sustainable Development of Agriculture of Ukraine in the Context of Climate Change

The purpose of the article is to actualize the challenges faced by Ukrainian agriculture in the context of climate change and the impact of the economic activity of enterprises on the state of natural resources, as well as to consider the ways and mechanisms of the post-war transition of Ukrainian agriculture to sustainable development. In the study, we used monographic, comparative analysis, empirical, abstract, and logical methods. The first consequences of climate change in agricultural sectors of the planet are characterized. Increasing temperatures to a maximum level, longer periods of extreme heat, more intense droughts, increased moisture deficit during the growing season, winter thaws, the spread of pests and diseases, and other manifestations of climate change have a negative impact on agricultural production. In the context of climate change, as highlighted in the paper, these negative processes will significantly intensify, requiring an immediate transition from ecologically and socially destructive monoculture to agroecological agriculture, which is recognized as one of the most affordable, low-cost, socially oriented, and environmentally relevant ways to transition to sustainable development of the industry. The principles and institutional support for such a transition are revealed, taking into account the expected climate change and post-war consequences for Ukrainian agriculture.

Arctic and red fox population responses to climate and cryosphere changes at the Arctic's edge.

Responses of one species to climate change may influence the population dynamics of others, particularly in the Arctic where food webs are strongly linked. Specifically, changes to the cryosphere may limit prey availability for predators. We examined Arctic (Vulpes lagopus) and red fox (V. vulpes) population dynamics near the southern edge of the Arctic fox distribution using fur harvest records from Churchill, Manitoba, Canada between 1955 and 2012. Arctic foxes showed a declining population trend over time (inferred from harvest records corrected for trapping effort), whereas the red fox population trend was relatively stable. The positive relationship between the annual Arctic and red fox harvests suggested interspecific competition did not promote the Arctic fox decline. To investigate alternative mechanisms, we evaluated the relative influence of sea-ice phenology, snow depth, snow duration, winter thaws, and summer temperature on the harvest dynamics of both species in the most recent 32years (1980-2012; n = 29) of our data. Arctic fox harvests were negatively related to the length of time Hudson Bay was free of sea ice. Shorter sea ice duration may reduce access to seal carrion as an alternative winter food source when lemming densities decline. Contrary to our prediction, red fox harvest was not related to summer temperature but was positively related to snow depth, suggesting winter prey availability may limit red fox population growth. Predators have an important ecological role, so understanding the influence of changes in the cryosphere on predator-prey interactions may better illuminate the broader influence of climate change on food-web dynamics.

Perennial forages in cold‐humid areas: Adaptation and resilience‐building strategies toward climate change

AbstractIn the continental cold and humid areas of northeastern North America, climate change by mid‐century may increase the yield potential of perennial forage species as a result of increased temperature and atmospheric CO2 concentration, and a longer growing season compared to the 1990−2000 period. More winter thaws and less snow cover along with more summer drought events, however, may reduce winter survival and summer regrowth, thus potentially reducing the persistence of perennial forages over time. Based on nearly two decades of research on the effects of climate change on forages in cold and humid areas of northeastern North America, through field experiments and modeling, we summarize in this review the expected effects of climate change on forage production in terms of yield, nutritive value, and winter survival. We also propose a set of 12 adaptation and resilience‐building strategies for forage systems that can be implemented at the field and farm levels. Research priorities for the future, including the improvement of species, forage management practices, and modeling tools, are also identified. Implementing strategies to alleviate or take advantage of the effects of a changing climate may improve productivity and resilience of well‐adapted forage systems in cold and humid areas.

3차원 공간 좌표 시스템과 드론 영상 검출을 활용한 산사태 안식각 예측에 관한 연구

Forest fires are representative natural disasters resulting from dramatic global climate change in these modern times. When forest formation is insufficient due to forest damage caused by fire, secondary damages such as landslides occur during the winter thawing period and heavy rains. In most countries, only a limited area is managed as CCTV-centered monitoring systems for forest management. For the landslide prediction, markers containing 3D spatial coordinates were located on the slopes of the danger areas in advance. Then 3D mapping and angle of repose were obtained by periodic drone imaging. The recognition range and angle of view of markers were defined, and a new method for predicting signs of landslides in advance was presented in this study.

Cold tolerance and winter survival of seasonally‐acclimatised second‐instar larvae of the spruce budworm, Choristoneura fumiferana

Abstract Field‐acclimatised spruce budworm larvae, Choristoneura fumiferana, supercool to as low as −41.6°C in winter months. Yet the extent to which they can withstand exposures to temperatures slightly above their supercooling point has never been investigated. In both January and February 2018, we tested various combinations of sub‐zero temperatures (−37 to −42°C) and exposure durations (0.75–12 h) to estimate the combinations of temperature and exposure durations required to kill half the population (LTT50). At −37 or −38°C, the estimated emergence probability was about 0.80 at all exposure durations. In contrast, the LTT50 was reached after 11.4 h at −39°C, 9.4 h at −40°C, and 3 h at −41°C. A temperature of −42°C was fatal to most larvae. During the winters of 2017, 2018 and 2019, survival experiments were conducted at three latitudes (46–48°N) in Québec. Regardless of the year or latitude, none of the daily minimum temperatures recorded in January or February were cold enough to reach the LTT50. However, the sudden drops in temperature that occurred after the winter thaw of March and in early December 2018 were likely responsible for the low proportions of emerged larvae observed. Hence, despite the high capacity of spruce budworm larvae to withstand very low sub‐zero temperatures in winter months, they remain highly vulnerable to cold spells during their early diapause or post‐diapause development. Such climatic disturbances deserve more attention, as they may increase under climate change.

EVALUATION OF ROMANIAN APPLE CULTIVARS IN LATVIA

Commercial apple growing in Latvia feels some lack of climate adapted modern cultivars. Development of fruits and trees is limited by active growth period (temperatures over 10 °C) of 135-150 days and active temperature sum of 1700-2100 °C. Winter hardiness also is essential, as temperatures below −30°C occur each 10 years, and winter thaws are frequent. Annual precipitation 692 mm favours development of fungal diseases. In 2016, a trial of four Romanian apple cultivars resistant to scab - ‘Aura’, ‘Ciprian’, ‘Jonaprim’ and ‘Romus 3’ was established in Latvia. Trees were grafted on dwarfing rootstock B.396 and planted as 1-year old whips in 3 replications with 2-3 trees in each replication, and trained as slender spindle. Commercial cultivars ‘Auksis’ (midseason) and ‘Ligol’ (late) were used as controls. Most trees of all cultivars in the 2nd year (2017) developed a well branched frame, from 37.5% trees of ‘Ciprian’ to 90% trees of ‘Jonaprim’. The first fruits were harvested in 2017, and commercially significant yield was achieved in 2018, except ‘Jonaprim’, which had the slowest yield increase. By the sum of yield in 2017-2021 ‘Aura’ and ‘Jonaprim’ surpassed commercial cultivar ’Auksis’, but were less productive than ‘Ligol’. Only slightly lower summary yield was obtained from ‘Ciprian’, while ‘Romus 3’ showed the lowest productivity and strong premature fruit drop. Very good taste panel results were obtained for ‘Aura’ and ‘Ciprian’, 7 to 8 points in average. Their fruits also kept well, to 5 months in common storage at 2 ±1oC. Fruits of the other two cultivars were too small and had mediocre or poor taste. The weather conditions in the trial years allowed to test susceptibility to spring frosts and drought. All cultivars showed good tree health after over-wintering. ‘Jonaprim’ and ‘Auksis’ in 2019 had the highest spring frost injury, 60-70% of fruits, while least injured were ‘Aura’ (21.5%) and ‘Ciprian’ (27.7%). Extreme drought in summer of 2021 led to low average fruit mass of all cultivars including the normally large fruited ‘Ligol’ (120-130 g), while in other years ‘Aura’ had fruits over 180 g, very attractive yellow with red stripes. Fruits of ‘Ciprian’ also had good size, but in some years too dark over-colour. ‘Aura’ and ‘Ciprian’ showed good adaptation to the climate of Latvia and can be recommended for wider trials at farms.

ОСОБЕННОСТИ ХИМИЧЕСКОГО СОСТАВА И КАЧЕСТВА ВОДЫ В БАССЕЙНЕ РЕКИ ЛЕНЫ

Introduction. The Lena River is one of the largest rivers in Russia and the main transport artery of Yakutia. Methods. In the course of the study, we considered the water regime of the Lena River in 1981–2019 in relation to the monthly average water discharge. The hydrochemical runoff was quantitatively assessed based on the widely used landscape-hydrological method. The analysis made it possible to estimate the relationship between the natural water quality and the environmental state of catchments. Results. An increase in the winter temperature reduced the depth of soil freezing and increased the drainage properties of soil as well as the number and duration of winter thaws. The most pronounced annual water discharge was observed in the Aldan River basin in the eastern part of the Lena River basin. The current state of the surface water quality was assessed by the main hydrochemical characteristics: water salinity, principal ions (sulfates (SO4 2–)), nutrients (nitrite nitrogen (NO2–)), organic matter (BOD5 and COD), oil products, phenols, and iron (Fe) and copper (Cu) compounds. The water has quality class 3 and is characterized as “polluted” or “very polluted” in different zones of the river basin, with the situation being most acute in the Olekma River. Conclusions. We present the results of an analysis of the spatial and temporal variations in the content of the most informative hydrochemical components for two periods (2001–2009 and 2010–2019) in the Lena River basin in accordance with the most stringent commercial fishing standards in force. We also plotted and mapped the temporal variations in the main pollutants. Graphs and maps of the time dynamics of the main pollutants are constructed.

WINTER HARDINESS OF THE PROSPECTIVE HYBRIDS OF THE CULTIVATED CHERRY PLUM

One of the chief limiting factors for the cultivated cherry plum in the central zone of Belarus is winter hardiness. The&#x0D; main components of cherry plum winter hardiness were studied by the method of artificial freezing. The main test modes&#x0D; were: resistance to autumn slight frosts and early frosts; the maximum value of frost resistance developed by plants after&#x0D; the end of organic dormancy; the ability to maintain resistance to low temperatures during the winter thaws, to restore frost&#x0D; resistance during re-hardening after thaws.&#x0D; In the field, as well as in artificial freezing in various modes, the vascular-conducting tissue of the bourgeon node&#x0D; turned out to be the most sensitive to freezing. Based on the results of a comprehensive assessment of the winter hardiness&#x0D; of cultivated cherry plum genotypes in the field and using the method of direct freezing, we can distinguish that the sources&#x0D; of winter hardiness of tissues of annual shoots are hybrids 09-10/46 (Lama × Gaviota) and 09-9/72 (Comet × Mara); sources&#x0D; of winter hardiness of generative buds are hybrids 09-3/22 (Puteshestvennitsa × pollen mixture), 09-9/61, 09-9/66, 09-9/72&#x0D; (Comet × Mara).

The Climatological Rise in Winter Temperature- and Dewpoint-Based Thaw Events and Their Impact on Snow Depth on Mount Washington, New Hampshire

AbstractWe analyze how winter thaw events (TE; T&gt;0°C) are changing on the summit of Mount Washington, New Hampshire using three metrics: the number of TE, number of thaw hours, and number of thaw degree-hours for temperature and dewpoint for winters from 1935-36 to 2019-20. The impact of temperature-only-TE and dewpoint-TE on snow depth are compared to quantify the different impacts of sensible-only and sensible-and-latent heating, respectively. Results reveal that temperature- and dewpoint-TE for all metrics increased at a statistically significant rate (p&lt;0.05) over the full time periods studied for temperature (1935-1936 to 2019-2020) and dewpoint (1939-1940 to 2019-2020). Notably around 2000-2001, the positive trends increased for most variables, including dewpoint thaw degree-hours that increased by 82.11 degree-hours decade-1during 2000-2020 – about five times faster than the 1939-2020 rate of 17.70 degree-hours decade-1. Furthermore, a clear upward shift occurred around 1990 in the lowest winter values of thaw hours and thaw degree-hours – winters now have a higher baseline amount of thaw than before 1990. Snow depth loss during dewpoint-TE (0.36 cm hr-1) occurred more than twice as fast as temperature-only-TE (0.14 cm hr-1). With winters projected to warm throughout the 21stcentury in the Northeastern US, it is expected that the trends in winter thaw events, and the sensible and latent energy they bring, will continue to rise and lead to more frequent winter flooding, fewer days of good quality snow for winter recreation, and changes in ecosystem function.

Climate‐induced yellow‐cedar decline on the island archipelago of Haida Gwaii

AbstractThe global rise in temperature and associated changes in climate have led to decline of forests around the globe, across multiple species and ecosystems. Yellow‐cedar (Callitropsis nootkatensis) decline is one of the most severe in North America. We found abundant evidence of tree decline and mortality on Haida Gwaii across multiple watersheds and over a range of elevations. This decline on Haida Gwaii parallels the broader yellow‐cedar decline in terms of spatial distribution, symptoms, magnitude, and timing. However, Haida Gwaii has a more temperate climate and ephemeral snowpack than declining yellow‐cedar forests in Alaska where the link to climate was first uncovered. Given these important differences, we investigated several possible drivers both at the local and at the regional scale, using population demography, dendrochronology, and daily weather data. We explored stand dynamics as a driver and tested the known link to climate. Our results are inconsistent with stand dynamics as a driver of elevated decline and mortality. Neither increased competition nor aging of a cohort explains the decline. Alternatively, the magnitude and timing of the decline are consistent with well‐documented long‐term directional trends in regional climate. Onset of basal area increment decline and mortality have been accumulating over time, with increased rates since the 1980s. Our sites were located at the edge of the expected range of mortality, and we found only four thaw–freeze events over the past ~80 yrs. However, superposed epoch analysis using daily weather data revealed that mortality and onset of decline events were associated with warmer winter conditions, consistent with the drivers from Alaska. Rather than isolated extreme thaw–freeze events, warmer winter temperatures on Haida Gwaii may mean less cold hardening throughout the winter, which exposes yellow‐cedar’s fine roots to varying degrees of freezing damage over multiple winter thaw–freeze cycles, causing physiological stress, tree decline, and eventual death.

Perpetuum's Sonata

Perpetuum's Sonata Matthew Burnside (Fifty-one things you've always known…) ________ The night S arrives, nothing hurts. As if every string of every violin ever plucked could be, in an instant, undone. Tenderly unteased—an entire history of haunting. Almost, as if, a harp; a lark of a lesson. As in, and all of it so nearly for naught, learning for the first time that we could deserve love. ________ Freakzilla, whose real name you could not for the life of you remember, for years pummeled a punching bag with your name tattooed vertically across its synthetic skin. He punched and punched and punched, every morning, until the name smeared into obscurity and his fists calcified like diamonds, at which point he let your name finally die. ________ The heat of your body, which provided your first love with warmth and gentleness at a time when the world couldn't have been colder to her that one afternoon in a field of ryegrass, wild zinnia, and narcissi, is still retained in the fingerprints of her right hand, caught in the whorling-grooved galaxies of her thumb, index finger, and pinkie. The skin remembers, even if memory cannot. ________ You would also be the first face your grandmother would see in the world after this one, who would lead her by the hand into the garden of her ancestors, whose fresh hands were already shuffling a brand new, bright-red deck under the stars. There she is! They would greet her, hooting and hollering. Sit down and cut 'em already, sister. And, while it is true she let you win every hand, she often had to cheat just to give you the satisfaction. [End Page 50] ________ 5.6 million dollars is roughly the same weight as a kangaroo, a beer keg, a toilet, and your standard-size octopus. When you were young you used to dream of wrestling an octopus in your bathtub. These days, you dream of wrestling the ocean, twilight, sand you cannot even see but reach out sometimes in your sleep to grab a fistful of. ________ The man who used to mow your lawn lives way out in the country now. Deconstructing any machine he can get his hands on, he rips out the engines, converts the rotors into breathtaking Dadaist configurations that he erects in the woods. Sometimes at night he walks through his impossible creations barefoot. In just the right light, with night slicing through the tree's gap tooth branches, shivering silvery the wings of warped blades with moonglow, he imagines himself a doomsday angel there to avenge all silence. ________ There your professor's novel sits, in a box with all the other novels in his campus office. He has never been to New York. He always hated the term 'slush pile'—that throwaway term for roadside sludge that inherits all the mud, soot, juices of a fresh winter's thaw. He doesn't mind what melts unseen under the sun's magnanimous strobe, but he does take issue with all that's buried thinking it deserves to be there. Tonight, he reads your short story aloud to himself, pacing up and down the staircase gesticulating wildly at the parts that move him so as to sweep his elbows and trace great, phantom lemniscates through the air like a conductor choregraphing ghosts singing the Star-Spangled Banner. You WILL be a writer, he scribbles in chicken scratch in the corner. Indeed, you already are one! After grading thirty papers he stares at the grass growing imperceptibly under his disintegrating tennis shoes. He believes in the inner lives of rocks, that every matter matters. How the birds move with such stirring force, phlegmatic repose even as they glide against the wind, going nowhere and everywhere. Coughing along campus, two minutes before class he X's out the lecture on prosody that he spent an hour transcribing and tells the students instead, "Making art is all good and well but please don't ever forget that you, too, are art" before cancelling class and encouraging them all to go whisk an insect out of danger and then go listen to a field...

МІНЛИВІ РИТМИ В РЕЖИМІ ҐРУНТОВИХ ВОД ТА ЇХНІЙ ЗВ'ЯЗОК З КЛІМАТИЧНИМИ ЧИННИКАМИ

Due to the anomalous changes in the groundwater regime over the past 5 years, the question arose about the adequacy and effectiveness of existing methods for predicting their level. The data of monitoring observations from 1951 in the upper part of the Southern Bug river basin are analyzed. The specific underground runoff to the river in the site of Khmilnyk was calculated by the finite difference method. It is established that at the end of the 80s of the last century a 7-8 year cycle began to appear in the fluctuations of the groundwater level (GWT) and groundwater runoff. It correlates well with the cyclicity of the air temperature, and, to a lesser extent, with the cycles of the monthly amount of precipitation. Instead, such rhythms are not at all typical of solar activity, which is characterized by 11-year and 5-6-year cycles. It is in connection with them that the heliosynoptic method of long-term prediction of RGV is based. It is likely that temperature changes occurring on Earth may change the "sun-induced" cyclicity of GWT, so this method of forecasting becomes ineffective. As there is no clear link between temperature changes and solar activity, it is possible that temperature changes are caused by human activity.From 2013-2015, with the beginning of the low water cycle in the study area, the anomalous minima in the GWT mode became more frequent and the cycles were transformed in the direction of their reduction (up to 5-6 years), which may indicate sharp changes in the nature of groundwater storage recovery. Deviations from 8-year cycles and differences in their duration in different parts of the same catchment area are primarily related to differences of GWT. Wavelet analysis was used as the main method of cyclic selection. Using multiple correlation analysis, it was found that in recent decades the temperature has reached a dominant position in terms of the impact on the groundwater regime (at their levels from 1.5 to 4.0 m). As a result, it was noted that our 7-8 year cycles are well traced during the relatively multi-water period caused by increased infiltration of groundwater due to increasing winter thaws (one of the most significant manifestations of global warming), and 5-6 year cycles correspond to low water periods.

The effects of soil aeration prior to dairy manure application on edge-of-field hydrology and nutrient fluxes in cold climate hayland agroecosystems

Soil aeration is increasingly being used on haylands in the northeastern United States as a water quality best management practice to decrease runoff volumes and flow rates, and the associated export of the nutrients nitrogen (N) and phosphorus (P). However, there is a lack of data on the effects of soil aeration on field-scale hydrologic and nutrient fluxes in cold-climate regions. The objective of this study was to evaluate the effects of soil aeration prior to dairy manure application on edge-of-field hydrology, water quality, and P fluxes in haylands in Vermont, United States, during both precipitation and snowmelt-induced runoff events. Edge-of-field water quality monitoring techniques were used to continuously measure the losses of surface runoff and the associated export of sediment and nutrients year-round from 2012 to 2018. Additionally, passive-capillary lysimeter systems were used to measure the subsurface losses of P. Aeration reduced total suspended solids, total P, total N, and total dissolved N mean runoff-event concentrations by 22%, 32%, 25%, and 34%, respectively. Event mean surface runoff volume increased by 16% due to aeration, resulting in no significant reductions in nutrient load exports during nonwinter runoff events. However, total P and total dissolved P loads were significantly reduced during large winter thaw events, often occurring months after aeration took place. Potential increases in surface and subsurface hydrologic flows that accompany nutrient export reductions should be considered before implementation of soil aeration on haylands with high runoff producing soils in cold climate regions.

Estimation of the frost resistance of the strawberry

As a result of the experiment, it was found that an increase in bound water and a decrease in free water in the leaves in the autumn are characteristic of strawberry plants against the background of a decrease in the level of total water content. The maximum ratio of bound water to free water based on the accumulation of sucrose and the amino acid proline was established in such varieties as ‘Solovushka’, ‘Tsaritsa’, ‘Sara’ and ‘Korona’. A high level of correlation was noted between the minimum air temperature and physiological and biochemical indicators of the formation of frost resistance of strawberries. A high correlation was established between the degree of freezing tolerance of strawberry plants and the fractional composition of water at the beginning of winter. In the early winter, the frost-resistant strawberry varieties ‘Solovushka’, ‘Rosinka’, ‘Tsaritsa’, ‘Korona’ and ‘Sara’ were characterized. The ability to stably maintain frost resistance during the winter thaw was shown by the varieties ‘Solovushka’, ‘Tsaritsa’ and ‘Korona’. As a result of the studies, frost-resistant strawberry varieties — ‘Solovushka’, ‘Tsaritsa’ and ‘Korona’ — were isolated.

Snowmelt periods as hot moments for soil N dynamics: a case study in Maine, USA.

The vernal transition represents the seasonal transition to spring, occurring as temperatures rise at the end of winter. With rapid snowmelt, microbial community turnover, and accelerated nutrient cycling, this is a critical but relatively under-studied period of ecosystem function. We conducted a study over two consecutive winters (2015-2016) at the Bear Brook Watershed in Maine to examine how changing winter conditions (warming winters, reduced snow accumulation) altered soil nitrogen availability and stream N export during winter and the vernal transition, and how these patterns were influenced by ecosystem N status (N-enriched vs. N-limited). Of the two study years, 2016 had a warmer winter with substantially less snow accumulation and a discontinuous snowpack-and as a result, had a longer vernal transition and a snowpack that thawed before the vernal transition began. Across both years, snowmelt triggered a transition, signaled by increased ammonium concentrations in soil, decreased soil nitrate concentrations due to flushing by meltwater, and increased stream nitrate exports. Despite the contrasting winter conditions, both years showed similar patterns in N availability and export, differing only in the timing of these transitions. The vernal transition has conventionally been considered a critical period for biogeochemical cycling, because the associated snowmelt event triggers physicochemical and biochemical changes in soil systems. This was consistent with our results in 2015, but our data for 2016 show that this may not always hold true, and instead, that warmer, low-snow winters may demonstrate a temporal asynchrony between snowmelt and the vernal transition. We also show that ecosystem N status is a strong driver of the seasonal N pattern, and the interaction of N status and changing climate must be further investigated to understand ecosystem function under our current predicted trajectory of warming winters, declining snowfall, and winter thaw events.

Study of frost resistance of cherry variety Turgenevka during on different rootstocks winter thaws

Relevance. The study of the resistance of garden cultures to unfavorable abiotic factors of the winter period is a priority direction of scientific studies, because the low winter hardiness can annul advantages the varieties on other signs. Concerning in the middle zone of Russia, studies on the resistance of cherry to frost during the thaw period remain relevant.Methods. The studies were carried out in the laboratory of physiology of fruit plant resistance at VNI-ISPKin2017-2018. The object of research was the Turgenevka cherry variety on new clonal root-stock of the Institute breeding were studied. Control - Turgenevka on the Rubin stock. For artificial freezing in early December the material was prepared for III and IV components of frost hardiness.Results. As a result of artificial freezing, the Turgenevka cherry variety was characterized by frost resistance of vegetative buds and tissues of annual shoots during a three-day winter thaw of + 2°C with a decrease in temperature of -25°C (III component of frost resistance). Inthiscase, thehighest frost resistance of the generative buds of the Turgenevka variety on rootstock 74340, 82987 is shown. After a three-day thaw of +2°C and repeated hardening with a subsequent decrease in temperature to -30°C in March (IV frost resistance component), the Turgenevka variety on the rootstock 74332, 74363, 82987 was characterized by frost resistance of vegetative buds, bark and wood of annualshoots. Moreover, in the studied scion-rootstock combinations, low frost resistance of the generative kidneys was revealed. Only in the studied variety on the rootstock 82987 was the largest percentage of living flower primordia revealed. The conducted studies revealed the Turgenevka variety in a rootstock of 82987 with the greatest potential for frost resistance during the winter thaws.

The impact of global climate change on the freezing tolerance of winter cereals in Western Canada

AbstractDue to global climate change in Western Canada, winter cereals will be exposed to a higher frequency of winter thaws which will increase crown water and thereby reduce freezing tolerance. Cold‐acclimated winter wheat (Triticum aestivum L.) and fall rye (Secale cereale L.) were held at −4°C under a snow cover for up to 120 days and periodically subjected to a dry or wet thaw for 3 days. Freezing tolerance was monitored by either the conventional freezing test (LT50) or the durational freeze test (LD50). There was a gradual loss in LT50 and LD50 in crowns held at −4°C, with the greatest loss after 120 days. The LT50 test could only identify species differences in freezing tolerance whereas LD50 identified cultivar‐specific differences. Rehardened plants previously subjected to a 4°C dry thaw regained an LT50 comparable to non‐thawed plants. Whereas plants exposed to a wet thaw could only partially reharden. The more freezing tolerant fall rye cultivars maintained a lower LT50 under thawing and rehardening conditions as compared with winter wheat. A short winter thaw dramatically reduced crown freezing tolerance. The selection of superior germplasm to tolerate warming winter conditions is an important goal for future winter wheat breeding efforts.