Summer Air Temperature Research Articles

Influence of Weather Conditions on the Spread of Fires in the Forest Fund of Zhytomyr Polesia

Fires are one of the critical factors in the weakening of forests. Given the high share of pine forests in the Zhytomyr Oblast, the conditions for fires are very favourable. Especially intense fires occurred in 2020, when rapid warming occurred in the spring, which in the absence of snow cover and the presence of intense winds in the February-March 2020 increased the fire danger in forests. The purpose of this study is to identify the features of the dynamics of the spread of fires in the forest stands of the Zhytomyr Oblast Department of Forestry and Hunting and assess the meteorological indicators that may affect their spread. Research methods: statistical – when analysing data on meteorological indicators and materials for accounting for forest fires. The study identified the specific features of the dynamics of fire spread in forest stands of Zhytomyr Oblast in 2014-2021. According to the analysis, there was a considerable increase in the number and area of fires in 2020 compared to the average figures for 2014-2019 and 2021 combined. During 2014-2021, 951 fires occurred on a forested area of 43,807.65 hectares. It was revealed that only 448 fires occurred in 2014-2019 and 2021, and 503 fires were recorded in 2020 on an area of 43,229 hectares. Among others, crown fires were recorded on an area of 6,389 hectares in the same 2020 year and on an area of 35.7 hectares in 2019 alone. The largest areas of crown fires were recorded on the territory of the State Enterprise “Ovrutske SF”, State Enterprise “Luhynske forestry”, State Enterprise “Ovrutske forestry” and State Enterprise “Slovechanske forestry”. The indicators of temperature, precipitation, and hydrothermal coefficient for 2014-2021 are analysed. The values of air temperature and precipitation were determined during the growing season, and the hydrothermal coefficient was calculated according to G.T. Selyaninov. The study established that the sum of air temperatures during the growing season was 3,127.6°C on average for 2014-2021. The highest temperature values were recorded during the growing season of 2018. According to the analysis of the amount of precipitation for the growing season 2014-2021, the indicators were set at 323.8 mm. The lowest precipitation rates were recorded in 2015. According to the ratio of temperature and precipitation indicators, the value of G.T. Selyaninov’s hydrothermal coefficient for the growing seasons of 2014-2021 was obtained, the average value of which was 1.04 units

Analysis, modelling and forecasting of crop yields using artificial neural networks

The article gives information about the attempt made to select configurations, train and test artificial neural networks for predicting yields of grain crops considering of climate changes. Peculiarities of agricultural production require constant improvement of methods for analyzing crop yields, time series, and longterm climatic characteristics. Preliminary statistical evaluation of the considered time series made it possible to identify certain patterns. Time series were divided into four intervals: for building a network, its training, testing and control. During the construction of artificial neural networks, three models were used: MLP - multilayer perceptron, RBF - r adial basis functions and GRNN - g eneralized regression neural network. Based on the results of the construction, the best model was chosen. The sum of active air temperatures and the sum of precipitation for the growing season was used for artificial neural networks at the input, and the crop yield was used at the output. The use of sets of neural systems, generated automatically, contributed to the effective forecasting of crop yields based on the analysis of climate data. As a result, according to the selected model, a yield forecast was made for the coming years considering climatic characteristics.

Regional, multi-decadal analysis on the Loire River basin reveals that stream temperature increases faster than air temperature

Abstract. Stream temperature appears to be increasing globally, but its rate remains poorly constrained due to a paucity of long-term data and difficulty in parsing effects of hydroclimate and landscape variability. Here, we address these issues using the physically based thermal model T-NET (Temperature-NETwork) coupled with the EROS semi-distributed hydrological model to reconstruct past daily stream temperature and streamflow at the scale of the entire Loire River basin in France (105 km2 with 52 278 reaches). Stream temperature increased for almost all reaches in all seasons (mean =+0.38 ∘C decade−1) over the 1963–2019 period. Increases were greatest in spring and summer, with a median increase of + 0.38 ∘C (range =+0.11 to +0.76 ∘C) and +0.44 ∘C (+0.08 to +1.02 ∘C) per decade, respectively. Rates of stream temperature increases were greater than for air temperature across seasons for the majority of reaches. Spring and summer increases were typically greatest in the southern part of the Loire basin (up to +1 ∘C decade−1) and in the largest rivers (Strahler order ≥5). Importantly, air temperature and streamflow could exert a joint influence on stream temperature trends, where the greatest stream temperature increases were accompanied by similar trends in air temperature (up to +0.71 ∘C decade−1) and the greatest decreases in streamflow (up to −16 % decade−1). Indeed, for the majority of reaches, positive stream temperature anomalies exhibited synchrony with positive anomalies in air temperature and negative anomalies in streamflow, highlighting the dual control exerted by these hydroclimatic drivers. Moreover, spring and summer stream temperature, air temperature, and streamflow time series exhibited common change points occurring in the late 1980s, suggesting a temporal coherence between changes in the hydroclimatic drivers and a rapid stream temperature response. Critically, riparian vegetation shading mitigated stream temperature increases by up to 0.16 ∘C decade−1 in smaller streams (i.e. < 30 km from the source). Our results provide strong support for basin-wide increases in stream temperature due to joint effects of rising air temperature and reduced streamflow. We suggest that some of these climate change-induced effects can be mitigated through the restoration and maintenance of riparian forests.

Modern aridity in the Altai-Sayan mountain range derived from multiple millennial proxies

Temperature and precipitation changes are crucial for larch trees growing at high-elevation sites covered by permafrost in the Altai-Sayan mountain range (ASMR). To contextualize the amplitude of recent climate fluctuations, we have to look into the past by analyzing millennial paleoclimatic archives recording both temperature and precipitation. We developed annually resolved 1500-year tree-ring cellulose chronologies (δ13Ccell, δ18Ocell), and used these new records to reconstruct the variability in local summer precipitation and air temperature. We combined our new local reconstructions with existing paleoclimatic archives available for the Altai. The data show a strong decreasing trend by ca. 49% in regional summer precipitation, along with a regional summer temperature increase towards the twenty-first century, relative to the preceding 1500 years. Modern dry conditions (1966–2016 CE) in the ASMR are the result of simultaneous summer warming and decreased precipitation. Our new reconstructions also demonstrate that climate change in the ASMR is much stronger compared to the global average.

Superensemble Approach to S2S Model for Predicting Surface Air Temperature in Summer in East Asia from 2016 to 2020

A multimodel superensemble technique was applied to improve the accuracy of a model predicting the subseasonal surface air temperatures in East Asia. Superensemble forecast data based on seven subseasonal-to-seasonal (S2S) forecast models were produced for the initial times from May to August in 2016–2020 and forecast days in weeks 1–4. Superensemble techniques based on the root-mean-square error ensemble mean (SUPR) and the linear regression coefficient ensemble mean (SUPL) were evaluated and compared with the forecast bias-removed ensemble mean (ENS) data. The magnitudes of the forecasting root-mean-square errors (RMSE) of the SUPR and SUPL methods were 4.2% and 13.8% lower, respectively, than that of the ENS method, and the most significant effect was in 2020. The RMSE improvements of SUPR and SUPL were high when the initial date was in May, June, and August, and the forecast date was within weeks 1–4. Applying multimodel superensemble methods effectively reduced the forecasting errors of the S2S models. If weight coefficients based on the characteristics of the models are appropriately applied, the forecasting performance can be significantly improved.

Influence of Climate Changes on Hydrothermal Regime of Dark Gray Podzolized Soil of Western Forest Steppe

Thermal properties of soil are important conditions that determine the nature and intensity of soil processes, but the features of the formation of thermal and water regimes of dark gray podzolized soil of the Ukrainian Forest Steppe are insufficiently studied. The purpose of the presented materials is to highlight the dynamics of the annual course of temperature and humidity of the air and dark gray podzolized soil to determine the peculiarities of the formation of its hydrothermal regime in modern agro-climatic conditions of the Forest Steppe zone. The study of soil temperature was carried out during 2008-2019 in the Rivne region using generally accepted standards and methods (DSTU ISO 11464-2007, DSTU ISO 11465-2001, DSTU B B.2.1-17:2009, DSTU B B.2.1-25:2009). Surface air temperature observations throughout the study period indicate an increase in average annual temperature, and five-year averages of the sum of effective air temperatures above 10°C show tends to increase. The study of the relationship between the temperature of the surface air layer and dark gray soil in the Rivne region confirmed that the correlation of these indicators is linear. Analyzing the dynamics of temperature indicators, it should be noted a significant increase in maximum soil temperatures, due to which there is an increase in average annual temperatures. Detailing of soil warming indicators according to the data of ten years showed that during 2008-2017 the soils warmed up much more than in the average during the whole period of meteorological observations. According to the accepted classification, the studied soils belong to the seasonally freezing type, moderately warm subtype and genus with medium heat supply. The results obtained during the study allow to justify changes in the hydrothermal conditions of dark gray podzolized soil and determine the needs for corrective measures in crop production to maintain sustainable yields and ensure enhanced fertility reproduction

Increasing impacts of extreme winter warming events on permafrost

Winter warming events (WWE) are abrupt and short-lasting (hours-to-days) events of extraordinarily warm weather occurring during wintertime, sometimes accompanied by rainfall (rain on snow events; ROS). Through direct heat transfer and changes in the snowpack properties, these events cause changes in the below-ground thermal regime that, in turn, controls a suite of ecosystem processes ranging from microbial activity to permafrost and vegetation dynamics. In addition, the overall impacts of WWE on ground temperatures may also depend on the timing of the events and the preceding snowpack characteristics. The frequency and intensity of these events in the Arctic, including the Swedish subarctic, has increased remarkably during the recent decades and is expected to increase even further during the 21st Century. In addition, snow depth (not necessarily snow duration) is projected to increase in many parts of the Arctic. In 2005, a manipulation experiment was set up on a lowland permafrost mire in the Swedish subarctic, to simulate projected future increases in winter precipitation. In this study, we analyse this 15-year record of ground temperature, AL thickness, and meteorological variables, to evaluate the influence of different types and timings of WWE on permafrost under different snowpack conditions. We found that all WWE types were strongly linked to permafrost warming in both the ambient and the manipulated plots during the winter months, but that significantly warmer summer ground temperatures and, consequently, thicker active layer (AL) were only linked to ROS events in manipulated plots. Additional long-term AL thickness data from nearby permafrost sites indicate an increasingly stronger influence of WWE over time since the mid-1990s, to the detriment of the influence of summer air temperatures.

Decline in biological soil crust N-fixing lichens linked to increasing summertime temperatures

Biological soil crusts (biocrusts), comprised of mosses, lichens, and cyanobacteria, are key components to many dryland communities. Climate change and other anthropogenic disturbances are thought to cause a decline in mosses and lichens, yet few long-term studies exist to track potential shifts in these sensitive soil-surface communities. Using a unique long-term observational dataset from a temperate dryland with initial observations dating back to 1967, we examine the effects of 53 y of observed environmental variation and Bromus tectorum invasion on biocrust communities in a grassland never grazed by domestic livestock. Annual observations show a steep decline in N-fixing lichen cover (dominated by Collema species) from 1996 to 2002, coinciding with a period of extended drought, with Collema communities never able to recover. Declines in other lichen species were also observed, both in number of species present and by total cover, which were attributed to increasing summertime temperatures. Conversely, moss species gradually gained in cover over the survey years, especially following a large Bromus tectorum invasion at the study onset (ca. 1996 to 2001). These results support a growing body of studies that suggests climate change is a key driver in changes to certain components of late-successional biocrust communities. Results here suggest that warming may partially negate decades of protection from disturbance, with biocrust communities reaching a vital tipping point. The accelerated rate of ongoing warming observed in this study may have resulted in the loss of lichen cover and diversity, which could have long-term implications for global temperate dryland ecosystems.

Hydroacoustics and concurrent experimental trawling reveal extreme annual variation in the density of 0+ pikeperch in late summer

The density and mean size of 0 + pikeperch (Sander lucioperca) were studied in late summer in 2004–2017 in clay-turbid and eutrophic Lake Tuusulanjärvi in southern Finland. Hydroacoustics and simultaneous experimental trawling were used to estimate the density of 0 + pikeperch. In some autumns, 0 + pikeperch was the most abundant species in the pelagic fish assemblage. However, the annual amplitude of pikeperch density was extremely high (1,300 - 19,900 individuals ha−1). The density and size variations of 0 + pikeperch were analysed in relation to air temperature sums and degree days. Unexpectedly, the density of 0 + pikeperch showed no correlation with the air temperature sums or degree days, but both the mean length and weight of 0 + pikeperch correlated positively with these temperature variables. The highest correlation coefficients between mean size and temperature were found with temperature sums over 10 °C and degree days over 5 °C. The correlation between density and condition of 0 + pikeperch was negative but non-significant. The high density of 0 + pikeperch in some autumns suggests that pikeperch may play a central role in the pelagic food web in eutrophic lakes – not only as a predator of planktivores but also by its own planktivory.

Climate and energy balance of the ground in University Valley, Antarctica

AbstractWe report 3 years of data from one meteorological and three smaller stations in University Valley, a high-elevation (1677 m) site in the Dry Valleys of Antarctica with extensive dry permafrost. Mean air temperature was -23.4°C. Summer air temperatures were virtually always < 0°C and were consistent with the altitude lapse rate and empirical relationships between summer temperature, distance from the coast and elevation. The measured frost point (-22.5°C) at the 42 cm deep ice table is equal to the surface frost point and above the atmospheric frost point (-29.6°C), providing direct evidence that surface conditions control ground ice depth. Observed peak surface soil temperatures reach 6°C for ice-cemented ground > 15 cm deep but stay < 0°C when it is shallower. We develop an energy balance model tuned to this rocky and dry environment. We find that differences in peak soil surface temperatures are primarily due to the higher thermal diffusivity of ice-cemented ground compared to dry soil. Sensitivity studies show that expected natural variability is insufficient for melt to form and significant excursions from current conditions are required. The site's ice table meets the criteria for a Special Region on Mars, with 30% of the year > -18°C and water activity > 0.6.

Improving the efficiency of agricultural land use in the South-East of the Saratov region in the face of climate change

The article analyzes climate change in the dry steppe regions of the Saratov region for the period from 1899–2018. and crop yields for the period from 1933–2018. The trends of improving the moisture supply of the territory in 1902–2007 are revealed. and its aridization in 2008–2018. Noted: an increase in the average annual air temperature and the sum of active air temperatures (≥10°C); decrease in the amount of winter negative air temperatures; increase (by 8–10 days) in the duration of the growing season (which is favorable for late-ripening varieties and hybrids); a decrease in soil freezing (due to which the volume of spring runoff of steppe rivers decreased from 50–95 to 3–19% of the total volume). The need to adapt crop production to changing climatic conditions is emphasized. Based on studies of the relationship between the cycles of 11 and 22-year solar activity (SA) with the amount of precipitation and the yield of grain crops in the Novouzensky district of the Saratov region, a forecast of favorable and unfavorable years for the cultivation of cereal crops was developed, which allows taking into account possible climatic risks and taking the necessary management decisions.

The Role of Soil Temperature Feedbacks for Summer Air Temperature Variability Under Climate Change Over East Asia

AbstractThe ongoing climate change has posed severe threat to the natural system and human society. However, how soil temperature feedbacks matter for climate change projections is not yet well explored. In this study, we assess the role of soil temperature feedbacks for summer air temperature variability over East Asia under global warming. Regional climate model simulations with and without soil temperature‐atmosphere interactions were performed to isolate the role of soil temperature feedbacks under historical (1976–2005) and future (2071–2100) warming conditions. Results indicate that soil temperature feedbacks can largely enhance interannual variability of summer daily mean and minimum surface air temperatures over East Asia, with strongest impacts over Mongolia and many areas of northern Tibetan Plateau and northern China, in the historical period. The soil temperature feedback strength below 925‐hPa mainly depends on changes in longwave radiation, surface heat flux partitioning, and temperature advections, while it is largely determined by the diabatic heating processes in the lower troposphere. The spatial distribution of soil temperature feedbacks is projected to change notably over East Asia under future warming condition. In particular, the impacts of soil temperature feedbacks on summer temperature are shown to be stronger in the lower troposphere under future condition. These results imply the important role of soil temperature feedbacks on air temperature variability for regional climate modeling especially in the context of climate change.

Large interannual variability in supraglacial lakes around East Antarctica

Antarctic supraglacial lakes (SGLs) have been linked to ice shelf collapse and the subsequent acceleration of inland ice flow, but observations of SGLs remain relatively scarce and their interannual variability is largely unknown. This makes it difficult to assess whether some ice shelves are close to thresholds of stability under climate warming. Here, we present the first observations of SGLs across the entire East Antarctic Ice Sheet over multiple melt seasons (2014–2020). Interannual variability in SGL volume is >200% on some ice shelves, but patterns are highly asynchronous. More extensive, deeper SGLs correlate with higher summer (December-January-February) air temperatures, but comparisons with modelled melt and runoff are complex. However, we find that modelled January melt and the ratio of November firn air content to summer melt are important predictors of SGL volume on some potentially vulnerable ice shelves, suggesting large increases in SGLs should be expected under future atmospheric warming.

Анализ климатических переменных в верховьях бассейна реки Амударья в Таджикистане

This article presents the results of the trend analysis of precipitation, maximum and minimum temperatures in the upstream of Amu Darya River Basin in Tajikistan. The result showed that in the south part of Tajikistan the trend of the summer and winter seasons indicate a positive and the temperature rises in summer and winter. In the north and central part of Tajikistan, there is also a positive trend in summer and winter with the exception of the Rasht and Murgab stations, where was recorded a decreasing trend in air temperature in summer. The eastern part of Tajikistan, where the high-altitude territory begins, the temperature trend shows that the summer period of the year becomes slightly cooler, and the winter period shows an increasing temperature trend, i.e. it is getting warmer. On the flat plain areas of Tajikistan, a relative increase in precipitation is observed, and the amount of precipitation in the high-mountain zone (eastern Pamir) decreases according to long-term data. This study shows pronounced climatic fluctuations in Tajikistan, changes in air temperature and precipitation conditions.

Climatic influences on active layer depth between 2000 and 2018 in the McMurdo Dry Valleys, Ross Sea Region, Antarctica

The maximum seasonal depth of thaw (the active layer depth) in permafrost soils is influenced by a range of soil and atmospheric variables. The active layer depth and the temperature at the top of the permafrost have potential to provide a clear signal of a changing climate, damping out noise more effectively than atmospheric variables. A monitoring network of nine soil climate stations was established in the McMurdo Dry Valleys between 1999 and 2012. Each station monitors soil temperature to a depth of up to 1.2 m, along with a range of atmospheric variables including air temperature, solar radiation, and wind speed.Over the period of record included in this study (2000–2018): the mean active layer depth ranged from 7.6 cm at Mt. Fleming to >90 cm at Granite Harbour; the mean annual shallow (15 cm) soil temperature ranged from −24 °C at Mt. Fleming to −14 °C at Granite Harbour; and the mean summer air temperature ranged from −11 °C at Mt. Fleming to −1 °C at Granite Harbour. There was marked between-year variation but no significant trends of increase or decrease in active layer depth, or temperature at the top of the permafrost, between 2000 and 2018.Wavelet analysis showed that both global and regional climate systems correlated with de-seasonalised temperature at the top of the permafrost. The Southern Annular Mode had relationships at both annual and biannual timescales (p < 0.05); the Southern Oscillation Index had a relationship at a 2–3 year timescale (p < 0.05); and the Amundsen Sea Low had an annual signal and some between season signals (p < 0.05).The data set is too short to draw conclusions on potential longer-term changes in the soil climate. Nevertheless, the database provides a baseline against which future change can be assessed and will increase in value the longer it is maintained.

Multi-Parameter Protocol for Geocryological Test Site: A Case Study Applied for the European North of Russia

An increase in air temperature leads to a significant transformation of the relief and landscapes of the Arctic. The rate of permafrost degradation, posing a profound change in the Arctic landscape, depends on air temperature, vegetation cover, type of soils, surface and ground waters. The existing international circumpolar programs dedicated to monitoring the temperature state of permafrost TSP (Thermal State Permafrost) and active layer thickness CALM (Circumpolar Active Layer Monitoring) are not sufficient for a comprehensive characterization of geocryological conditions. Yet, no standardized protocol exists for permafrost monitoring and related processes. Here, we propose a novel multi-parameter monitoring protocol and implement it for two sites in the European part of the Russian Arctic: the Yary site along the coast of the Baydaratskaya Bay in the Kara Sea (68.9° N) within the continuous permafrost area and the Hanovey site in the Komi Republic (67.3° N) within the discontinuous permafrost area. The protocol includes drilling boreholes, determining the composition and properties (vegetation cover and soils), snow cover measurement, geophysical imaging, active layer estimation and continuous ground temperature measurements. Ground temperature measured in 2014–2020 revealed that amplitudes of surface temperature fluctuations had no significant differences between the Yary and Hanovey sites, while that the mean annual temperatures between the areas had a considerable difference of greater than 3.0 °C. The period of the presence of the active layer changed with the year (e.g., ranging between 135 and 174 days in the Yary site), showing longer when the air temperatures in summer and the preceding winter were higher. Electrical resistivity tomography (ERT) allowed determining the permafrost distribution and active layer thicknesses. Thermometry results were consistent with our geophysical data. Analyzing the composition and properties of frozen soils helped better interpret the data of geophysical and temperature measurements. By integrating the study of the soil properties, ground temperatures, and ERT, our work allowed us to fully characterize these sites, suggesting that it helps better understand the thermal state at any other research sites in the European north of Russia. Our suggested monitoring protocol enables calibrating and verifying the numerical and analytical models of the heat transfer through the earth’s surface.

Influence of Azolla incorporation and/or dual cropping on CH4 and N2O emission from a paddy field

ABSTRACT Our previous pot experiments showed that using Azolla either or both as dual and green manure with rice increases its yield or significantly reduces either or both methane (CH4) and nitrous oxide (N2O) emissions. To confirm these findings in an actual field, Azolla was either grown as a dual crop (herein Cover) or incorporated as green manure plus dual cropping (herein AGM + Cover) at the beginning of the experiment along with rice. Compared with the control (chemical fertilizer; herein NPK), NPK + Cover and AGM + Cover treatments did not influence cumulative CH4 emissions throughout the rice growth period. However, AGM + Cover treatment affected significant CH4 emissions at early, middle, and later rice growth stages by 140.6%, 24.6%, and 33.1%, respectively, compared with NPK + Cover treatment. These emissions were attributed to the readily available carbon substrate for methanogens following the incorporation of Azolla as green manure. Compared with NPK, NPK + Cover and AGM + Cover significantly increased N2O emissions by 645.9% and 816.2%, respectively, during the middle rice growth stage. No significant N2O emission differences were observed in the three treatments in the early or later rice growth stages. The higher N2O emissions from the middle rice growth stage were ascribed to high substrate availability from the dead Azolla by higher summer air temperature in the 2019 season. AGM + Cover significantly decreased rice yield by 37.5% (NPK) and 35.3% (NPK + Cover), with no significant differences between NPK and NPK + Cover. This reduction was attributed to nitrogen immobilization from the incorporated Azolla during the early stage. Therefore, to ascertain the potential of Azolla in paddy fields to address environmental safety while sustaining yield, emphasis on the interaction of different application methods with various management practices is necessary.

Interannual variability of air temperature inversions in ice-free area of northern James Ross Island, Antarctica

Air temperature inversions are common features in Antarctica, especially in the interior where they are observed nearly year-round. Large temporal variability of air temperature inversion incidence is typical for the coastal areas and little is known about its occurrence in the Antarctic deglaciated areas. Here we present a 12-year-long time series of near-surface air temperature inversion derived from two automatic weather stations situated at different altitudes (10 and 375 m a.s.l.) in ice-free part of northern James Ross Island (Antarctic Peninsula). The highest monthly relative frequency of temperature inversions during 2006–2017 was observed in July (38%) when the range between minimum and maximum monthly frequencies reached 34%. Both the lowest monthly relative frequency of temperature inversions and the range were found in December with values of 7% and 15%, respectively. The correlation between mean lapse rate and selected mesoscale flow characteristics were tested. The highest correlations were found between lapse rate and specific humidity for the yearly means (0.69 in the 925 hPa pressure level). Negative correlation coefficients were established between lapse rate and air temperature in summer (− 0.65 in the 500 hPa pressure level). Finally, we also used the Weather and Research Forecasting (WRF) model to ascertain its ability to simulate situations as complicated as near-surface air temperature inversion formation in complex terrain. For a strong winter air temperature inversion, simulated air temperature was compared with in situ observations to assess the model performance.

ADAPTIVE POTENTIAL OF FENUGREEK SPECIES AT DIFFERENT SOWING TIMES

Among the unexplored technological elements of growing fenugreek in the conditions of Ukraine is the creation of conveyor cultivation of the culture. Therefore, the problem of the influence of sowing dates on the growth and development of plants, the parameters of the harvest and the qualitative composition of marketable products is acute. The purpose of this study was to substantiate the optimal sowing dates of fenugreek species to increase the yield of dried products in the conditions of Polissia on sod-podzolic soils. The leading methods employed to investigate this issue were the field method – to find the interaction of the object of research with biotic and abiotic factors, statistical method – to evaluate the research results to find the parameters of fenugreek’s adaptive capacity. During 2012-2014, for different sowing periods, the average yield of dry mass in blue fenugreek varied from 0.5 to 1.3 t/ha, and in hay fenugreek – from 0.6 to 1.5 t/ha. The early spring period and the late spring period of the 1st sowing period were characterized by the highest overall adaptive capacity. The highest value of the specific adaptive capacity was established during the late spring 2nd sowing period. The relative stability index ranged from 2.6 to 11.4. Blue fenugreek during the late spring 1st and 2nd sowing periods responds well to improved growing conditions (bi &gt;1), and fenugreek hay during the late spring 2nd and summer sowing periods. Early spring and late spring 1st sowing period samples are characterized by high breeding value. An increase in the sum of effective temperatures by 1°C contributed to the fluctuation of green mass yield from 4.82 to 128 kg/ha, and dry mass yield from 0.401 to 6.63 kg/ha. At the same time, an increase in precipitation by 1 mm affected the fluctuation of the yield of green mass from 15.0 to 146 kg/ha, and of dry mass from 0.145 to 25.9 kg/ha. Commercial production of fenugreek species was formed within the range of the sum of air temperatures (&gt;10°C) 383.9-487.1°C, the amount of precipitation 70.7-144.3 mm, and the growing season ranged from 35 to 55 days. The highest productivity of fenugreek species was found during sowing from the second decade of April to the first decade of May. The materials of this paper are of practical value for expanding the species diversity of vegetables and increasing the supply of the population with valuable food products and during the application of new and improved elements of technologies for growing valuable rare crops to achieve the maximum effect of fulfilling the genetic potential of plants

No evidence for a negative effect of growing season photosynthesis on leaf senescence timing.

The length of the growing season has a large influence on the carbon, water, and energy fluxes of global terrestrial ecosystems. While there has been mounting evidence of an advanced start of the growing season mostly due to elevated spring air temperatures, the mechanisms that control the end of the growing season (EOS) in most ecosystems remain relatively less well understood. Recently, a strong lagged control of EOS by growing season photosynthesis has been proposed, suggesting that more productive growing seasons lead to an earlier EOS. However, this relationship has not been extensively tested with in-situ observations across a variety of ecosystems. Here, we use observations from 40 eddy-covariance flux tower sites in temperate and boreal ecosystems in the northern hemisphere with more than 10years of observations (594site-years), ground observations of phenology, satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS), and three leaf senescence models to test the extent of a relationship between growing season photosynthesis and end of season senescence. The results suggest that there is no significant negative relationship between growing season photosynthesis and observed leaf senescence, flux-inferred EOS estimates, or remotely sensed phenological metrics, in most ecosystems. On the contrary, while we found negative effects of summer air temperatures and autumn vapor pressure deficit on EOS, more productive growing seasons were typically related to a later, not earlier, EOS. Our results challenge recent reports of carry-over effects of photosynthesis on EOS timing, and suggest those results may not hold over a large range of ecosystems.