Frost-free Period Research Articles

Determinants of nectar production in oilseed rape

With the aim of contributing to the development of models forecasting the melliferous characteristics and the potential honey yield of oilseed rape, we analyzed data on the temporal pattern of number of oilseed rape flowers, nectar secretion, sugar concentration, and weight of bee hives in relation to meteorological parameters, across three seasons of oilseed rape production in Denmark. The analyses showed that the time of flowering of oilseed rape is governed by degree days, while the number of flowers at the onset of flowering is determined by the preceding climatic conditions, with long frost-free periods in the beginning of a year (January–March) leading to the setting of more flowers. On the other hand, the decrease in the number of open oilseed rape flowers during the flowering period seems to be governed exclusively by inherent characteristics of oilseed rape. A late flowering in 2013 was associated with significantly reduced quality of the nectar in terms of both volume and sugar concentration, and our results suggest that the oilseed rape in this year did not contribute notably to bee colony development. In years in which the oilseed rape flowered around the normal time (beginning of May), the amount of secreted sugar decreased over the flowering period, being governed by inherent oilseed rape characteristics modified by climatic factors preceding the onset of flowering, as well as climatic conditions during flowering. The exploitation of oilseed rape nectar by bee colonies was found to be influenced by the amount of secreted sugar, as well as by the temperature conditions and the strength of the colony during flowering. Our results will assist beekeepers in predicting nectar production and sugar yield in oilseed rape and the ability of bees to exploit the sugar.

The Study of Frost Occurrence in Free State Province of South Africa

The study investigated the cessation, onset, and duration of light, medium, and heavy frost in Free State province of South Africa using minimum temperatures from 1960 to 2015. Trends in the frost indices were assessed using the Man-Kendall test. Onset of frost varied spatially with earlier onset over the northern, eastern, and southeastern parts. Areas of early onset also experience late cessation of frost resulting in shorter growing period of less than 240 days. The western parts have longer growing period exceeding 240 days due to earlier cessation of frost and relatively late onset of frost. Trends for the frost-free period (growing period) show contrasting negative and positive trends with isolated significant trends.

Isotopic heterogeneity in whitebark pine (Pinus albicaulis Engelm.) nuts across geographic, edaphic and climatic gradients in the Northern Rockies (USA)

The overall health and persistence of whitebark pine is of international concern. Extensive tree mortality and loss of vigor due to the non-native pathogen white pine blister rust (Cronartium ribicola A. Dietr.), mountain pine beetle (Dendroctonus ponderosae Hopkins), altered fire regimes, and climate change endanger the existence of whitebark pine, which is an important food source (pine nuts) for several wildlife species. Prior stable isotope analysis revealed variability in intrinsic water-use efficiency and nutritional status; however, small sample sizes prohibited the identification of geo-climatic effects on those isotopes. We summarize carbon isotope discrimination (Δ13C, a measure of intrinsic water-use efficiency) and the natural abundance of δ13C, δ15N and δ34S in whitebark pine nuts in the Northern Rockies. Spatial differences in geography, soil parent material and climate (e.g., summer mean temperature, number of degree-days below 0°C, mean annual precipitation, Hargreaves climatic moisture deficit, and the frost-free period) contributed to the low to moderate spatial resolution in selected models (R2 values ranged from 0.24 to 0.51). The importance of soil parent material in all models demonstrated whitebark pine exhibits previously unknown edaphic variation. Identification of the mechanistic drivers contributing to spatial heterogeneity in Δ13C provides an opportunity to select seed sources better suited to optimize long-term survival, vigor and cone production. Matching genetic resources to sites projected to support whitebark pine in future climates would ensure species persistence, while safeguarding an important wildlife food. Suitable wildlife habitat for projected warmer, drier climates was characterized as low values of Δ13C (<13.5‰) and was concentrated in the southeastern portion of the Northern Rockies. Whitebark pine nuts at the landscape scale exhibited unique δ34S and δ15N values relative to other wildlife foods, but these isotope values can overlap other plant materials in more localized areas. Future applications to determine the proportion of pine nuts in assimilated diets will need to accommodate spatial heterogeneity, potential temporal variation in δ13C, nutrient concentrations, animal tissue turnover rates, and seasonal availability of other foods. Further studies of the abiotic and biotic factors on C, N, and S cycles and the relationship between photosynthetic and heterotrophic tissue are needed for a better mechanistic understanding of the determinants of the natural abundance of δ13C, Δ13C, δ15N and δ34S.

Trends in agricultural heat and solar radiation resources in Northeast China: A multistage spatio‐temporal analysis

ABSTRACTClimate change has changed the distribution of climate resources in crop growing season, and caused some impacts on agricultural production. Based on daily meteorological data collected at 71 meteorological stations in Northeast China, trends at multi‐temporal scales (decadal, annual, monthly, and 10‐day) and spatial patterns of heat resources [temperature, frost‐free period (FFP)] and solar radiation resources [growing season's sunshine hour (GSS)] are estimated over the period 1961–2012.The period of 2000–2012 has been successively warmer than the previous decades with higher mean values for both temperature and FFP, and temperature had an abrupt increasing change in the 1980s. An increasing trend was identified for the daily mean temperature in the study area, with the trend value (0.30 °C decade−1) double the global warming rate (0.14 °C decade−1). As the last frost date advanced by 1.9 days decade−1 in spring and the first frost date delayed by 1.6 days decade−1 in fall, FFP increased by 17.9 days in recent 52 years with the average trend value of 3.5 days decade−1. Temperature in February exhibited the highest increasing rate; furthermore, the maximum temperature trends occurred in the last 10 days of February at most stations. Daily sunshine hours decreased in June, July, and August, but GSS showed small changes at decadal and annual scales because of the prolonged FFP.In summary, climate change has prolonged FFP, increased the heat resource, and slightly changed solar radiation resource during crop growing season, which is beneficial for agriculture in Northeast China.

Design of an Optimal Soil Moisture Monitoring Network Using SMOS Retrieved Soil Moisture

Many methods have been proposed to select sites for grid-scale soil moisture monitoring networks; however, calibration/validation activities also require information about where to place grid representative monitoring sites. In order to design a soil moisture network for this task in the Great Lakes Basin (522 000 km2), the dual-entropy multiobjective optimization algorithm was used to maximize the information content and minimize the redundancy of information in a potential soil moisture monitoring network. Soil moisture retrieved from the Soil Moisture and Ocean Salinity (SMOS) mission during the frost-free periods of 2010–2013 were filtered for data quality and then used in a multiobjective search to find Pareto optimum network designs based on the joint entropy and total correlation measures of information content and information redundancy, respectively. Differences in the information content of SMOS ascending and descending overpasses resulted in distinctly different network designs. Entropy from the SMOS ascending overpass was found to be spatially consistent, whereas descending overpass entropy had many peaks that coincided with areas of high subgrid heterogeneity. A combination of both ascending and descending overpasses produced network designs that incorporated aspects of information from each overpass. Initial networks were designed to include 15 monitoring sites, but the addition of network cost as an objective demonstrated that a network with similar information content could be achieved with fewer monitoring stations.

Effects of dormant and growing season burning on surface fuels and potential fire behavior in northern Florida longleaf pine (Pinus palustris) flatwoods

Prescribed fire is widely used to manage fuels in high-frequency, low-severity fire regimes including pine flatwoods of the southeastern USA where prescribed burning during the growing season (the frost-free period during the calendar year) has become more common in recent decades. Growing season prescribed fires address ecological management objectives that focus on increasing herb cover and decreasing shrub cover. The shift from shrub to herb dominance due to burning in the growing season corresponds to a change in surface fuels that could affect fire behavior, yet little has been done to assess the potential effects. We examined the effects of season-of-burn on shrub and herbaceous fuel layers and predicted fire behavior at replicate plots on frequently burned mesic pine flatwoods for two season-of-burn treatments (growing and dormant season prescribed fires) in two geographic regions in northern Florida. The Fuel Characteristic Classification System was used to construct a representative fuelbed for each plot at each sampling time to predict fire behavior. Predicted fire behavior was tested for correlation with measured surface fuel properties to determine if there was an effect from differences in fuels characteristics across treatments. In addition, fire temperature was measured in situ as a proxy for fire intensity and tested for treatment effects on the re-growth of live surface fuels. Compared to single dormant season burns, our single growing season burns caused no changes to live understory fuels and had no detectable effect on fire behavior, although predicted rate of spread and flame length were significantly reduced after all prescribed burns. Shrub cover and predicted fire behavior were, however, significantly different between geographic regions, and shrub height was significantly affected by fire temperature. Predicted fire behavior was strongly correlated with measures of the litter and herb strata. Results from this study suggest that land managers should not initially expect large changes in understory fuel properties or potential fire behavior from a shift to burning during the growing season and show that geographic location and fire intensity had significant effects on live fuels and potential fire behavior.

Estimación de la densidad de especies de coníferas a partir de variables ambientales

Las coníferas son la fuente más importante de materia prima para la industria forestal mexicana, cumplen funciones ecológicas importantes y proveen bienes y servicios para el hombre. Para probar si es posible predecir la densidad de las especies de coníferas a partir de las variables ambientales, se hizo un análisis de regresión lineal múltiple por el método paso por paso (stepwise). Se estudiaron veinte especies de cinco géneros distintos y once variables ambientales (nueve variables climáticas, una fisiográfica y otra de suelo). En este trabajo se detectó una escasa relación lineal entre la densidad de especies y las variables predictivas; no obstante, algunos indicadores sugieren que en 60% de las especies, la densidad es afectada principalmente por al menos cuatro variables ambientales; entre las que destacan la precipitación de abril a septiembre, el fenómeno de las heladas, la altitud sobre el nivel del mar y la precipitación media anual.

Influence of ecological factors on the production of active substances in the anti-cancer plant Sinopodophyllum hexandrum (Royle) T.S. Ying.

The quality of traditional Chinese herbal medicine, which plays a very important role in the health system of China, is determined by the active substances produced by the plants. The type, content, and proportion of these substances may vary depending on ecological factors in areas where the plants are grown. Sinopodophyllum hexandrum (Royle) T.S. Ying, an endangered plant species with great medical value, was investigated in eight production locations representative of its natural geographical distribution range in China. The correlation between the contents of the active ingredients extracted from the roots and rhizomes of S. hexandrum and the ecological factors were evaluated step-by-step using a series of computational biology methodologies. The results showed that ecological factors had significant effects on the contents but not on the types of the active ingredients in eight production locations. The primary ecological factors influencing the active substances included the annual average precipitation, July mean temperature, frost-free period, sunshine duration, soil pH, soil organic matter, and rapidly available potassium in the soil. The annual average precipitation was the most important determinant factor and was significantly and negatively correlated with the active ingredient contents (P < 0.001). In contrast, organic matter was the most important limiting factor and was significantly and positively correlated with the active substances. These ecological factors caused 98.13% of the total geographical variation of the active ingredient contents. The climate factors contributed more to the active ingredient contents than did the soil factors. It was concluded that from the view of the contents of the secondary metabolites and ecological factors of each growing location, in Jingyuan, Ningxia Province, and Yongdeng, Gansu Province, conditions were favorable to the production of podophyllotoxin and lignans, whereas in Shangri-La, Yunnan Province, and Nyingchi, Tibet, conditions were favorable to the production of quercetin and kaempferol.

Single and double crop systems in the Argentine Pampas: Environmental determinants of annual grain yield

New avenues are being explored to increase food production in the extensive agriculture of highly productive temperate regions. Intensifying the use of land by sequencing two crops in a season (double cropping) may enhance annual land productivity in relation to single annual crops. Single soybean (Glycine max L. Merr.) and maize (Zea maize L.) are widespread in the Argentine Pampas while wheat (Triticum aestivum L.)–soybean double crop system is the most common land-intensive cropping system. The possibility for expanding the double cropping system is large although it has received insufficient attention. The objectives of the present study were to (i) describe the association between major environmental variables and grain yield of wheat–soybean double crop, maize and soybean single crops and (ii) compare their annual grain yield over a wide range of environments as a basis to evaluate the possible contribution to productivity expected from wheat–soybean double crop compared with maize and soybean single crops. Yield data from farms widely distributed across the Argentine Pampas and meteorological information from 30 stations distributed in the region were recorded and analyzed. A five-year period of on-farm yields were obtained from 132 groups of farmers nested in 11 zones. Variables analyzed were crop grain yields, glucose equivalents grain yields, rainfall, temperature, radiation, and frost-free period. The ratio between radiation and temperature (photo-thermal quotient; PTQ) was also considered as a grain yield determinant for wheat. Mean daily temperature during crop reproductive stages was an important determinant of maximum yields for all crops as described by a boundary-function fit. The highest grain yields of maize and soybean were obtained at moderate summer temperatures (21.8–23.5°C and 21.8–23.8°C, respectively). Wheat maximum yields increased with low spring temperatures (<18.3°C), following high photo-thermal quotients during reproductive stages. In contrast, the highest yields of double crop soybean were obtained at high summer temperatures (>21.2°C), which were associated with extended frost free periods. High yields of the wheat–soybean double crop system were obtained with cool temperatures during spring combined with a relatively extended frost free period and substantial summer rainfall. On-farm yields below the boundary-function appeared associated to low rainfall scenarios, especially in double cropped soybean fields. The geographical patterns of yield for wheat–soybean double crop system tended to be similar to that of maize and soybean single crops. The most highly productive area for the three cropping systems evaluated was located in the center of the Argentine Pampas. However, wheat–soybean double crops were more productive than soybean at any site, but their yields were slightly lower than those of maize. In addition, the work helped to identify possible areas where wheat–soybean double crop system may give relative higher advantages; particularly, in some of the currently least productive areas. Since nowadays, almost 60% of the studied area is sown with single soybean, the results suggest that there is an effective possibility to have a substantial increase in on-farm productivity, while still producing soybean, simply by expanding the double crop system.

Partitioning of multivariate phenotypes using regression trees reveals complex patterns of adaptation to climate across the range of black cottonwood (Populus trichocarpa).

Local adaptation to climate in temperate forest trees involves the integration of multiple physiological, morphological, and phenological traits. Latitudinal clines are frequently observed for these traits, but environmental constraints also track longitude and altitude. We combined extensive phenotyping of 12 candidate adaptive traits, multivariate regression trees, quantitative genetics, and a genome-wide panel of SNP markers to better understand the interplay among geography, climate, and adaptation to abiotic factors in Populus trichocarpa. Heritabilities were low to moderate (0.13–0.32) and population differentiation for many traits exceeded the 99th percentile of the genome-wide distribution of FST, suggesting local adaptation. When climate variables were taken as predictors and the 12 traits as response variables in a multivariate regression tree analysis, evapotranspiration (Eref) explained the most variation, with subsequent splits related to mean temperature of the warmest month, frost-free period (FFP), and mean annual precipitation (MAP). These grouping matched relatively well the splits using geographic variables as predictors: the northernmost groups (short FFP and low Eref) had the lowest growth, and lowest cold injury index; the southern British Columbia group (low Eref and intermediate temperatures) had average growth and cold injury index; the group from the coast of California and Oregon (high Eref and FFP) had the highest growth performance and the highest cold injury index; and the southernmost, high-altitude group (with high Eref and low FFP) performed poorly, had high cold injury index, and lower water use efficiency. Taken together, these results suggest variation in both temperature and water availability across the range shape multivariate adaptive traits in poplar.

'Beibinghong': A new grape cultivar for brewing ice red wine

Introduction: The winters of northeast China are very cold. The existing cultivars of grape (Vitis vinifera L.) like 'Cabernet Sauvignon', 'Cabernet Franc', 'Riesling' and 'Chardonnay' etc. cannot mature and cannot survive through the winter because of the insufficient accumulated temperature and short frost-free period. Vitis amurensis Rupr. is a wild grapevine species originating from East Asia and is mainly distributed in Korea, Japan, and China. As one of the most cold-tolerant grapes, its stem can endure -40 to -50 °C. It also exhibits resistance to grape white rot and grape anthracnose which can severely damage Vitis vinifera grown worldwide. The Vitis amurensis grape berries have the characteristics of four highs and three lows, namely: high acidity, high tannin and polyphenols, high dry extract and high nutrition; low sugar, low juice yield, and low fermentation temperature. In view of these current situation, a new grape cultivar 'Beibinghong' was selected through multi-generation hybrids between species (Vitis amurensis and Vitis vinifera). The cultivar, released in 2008, overcomes the characteristic of Vitis amurensis being usued only for brewing sweet red wine. The cultivar is suitable for brewing dry red and ice red wine.

Frost periods and frost-free periods in Poland and neighbouringcountries

AbstractThe main objective of this article is to analysethe multiannual variability of frost occurrence and thelength of the frost-free period in Poland and neighbouringcountries between 1971 and 2010. A frost day was de-fined as a day onwhich the minimum temperaturewas below0°C and the maximum temperature was above 0°C.On average, between March and November, there were 30frost days in Poland and neighbouring countries, and theirnumber ranged between 12 and 61. In the analysed multiannualperiod, there was a statistically significant tendencyfor the last spring frost to be earlier. Conversely,the first autumn frost occurred increasingly late, althoughthe changes were not statistically significant. All but threestations (Augsburg, Kaliningrad, Olsztyn) recorded an increasein the length of frost-free periods, which was statisticallysignificant in 51% of stations. The pressure conditionconducive to the occurrence of frosts was anticycloniccirculation, as confirmed by the SLP and z500 hPa mapswhich were drawn up, and the Grosswetterlagen (GWL)classification types which were distinguished.

Regeenera of Tartary Buckwheat Seedlings

Regeneration of tartary buckwheat seedlings is a new cultural technology concerning One-year-two-harvest of tartary buckwheat. Buckwheat was planted 30-40 days ahead in a frost-free period of 120-130 days in main buckwheat-producing regions so that the soil can be made full use during dormant phase. Then, buckwheat can be harvested twice. Firstly, when the tartary buckwheat seedlings grow up, it could be harvested during bud period to the beginning of florescence as a green vegetable. And then the tartary buckwheat grains were harvested after autumn. The technology allows farmers increase production of buckwheat, extends the processing industry chain of agricultural product and promotes economic growth in rural origin. Through introducing and trial planting tartary buckwheat variaties of Heifeng1, Hunan7-2, Ding 98-1, 2518, Liner, Huating, Zhuanglang, Tongxin, Gewan. et.al were selected for seeding regeneration.

Landscape genetics and genetic structure of the southern torrent salamander, Rhyacotriton variegatus

Landscape genetic methods can be used to identify the most effective conservation measures to maintain functional connectivity among populations. Analyses of habitat factors that facilitate or restrict gene flow are particularly useful for species with specific habitat requirements and low dispersal rates. Rhyacotriton variegatus is a salamander species with low desiccation tolerance and a restricted geographic range, limited to the Pacific Northwest. Thus, we predicted that genetic distance would be positively correlated with climate and landscape variables that increase risk of desiccation. Two genetic distance measures, pairwise FST and proportion of shared alleles (DPS), suggested that gene flow was low among 19 sampling localities (367 total individuals) and genetic structure was high overall (DPS = 0.636 ± 0.010, FST = 0.330 ± 0.011; mean ± SD). Using both least-cost path and Circuitscape models of landscape resistance, we found that low stream cover, low canopy cover, high heat-load index, and short frost-free period all restricted gene flow among populations. We suggest that the conservation status of this species be revisited given this evidence of high genetic structure within the species, the level of habitat fragmentation in their range, and their reliance on dense canopy cover for dispersal. Maintaining stream corridors with buffers of dense canopy cover may maximize connectivity despite the pressures of timber harvest and urbanization.

Fine-spatial scale predictions of understory species using climate- and LiDAR-derived terrain and canopy metrics

Food and habitat resources are critical components of wildlife management and conservation efforts. The grizzly bear (Ursus arctos) has diverse diets and habitat requirements particularly for understory plant species, which are impacted by human developments and forest management activities. We use light detection and ranging (LiDAR) data to predict the occurrence of 14 understory plant species relevant to bear forage and compare our predictions with more conventional climate- and land cover-based models. We use boosted regression trees to model each of the 14 understory species across 4435 km2 using occurrence (presence–absence) data from 1941 field plots. Three sets of models were fitted: climate only, climate and basic land and forest covers from Landsat 30-m imagery, and a climate- and LiDAR-derived model describing both the terrain and forest canopy. Resulting model accuracies varied widely among species. Overall, 8 of 14 species models were improved by including the LiDAR-derived variables. For climate-only models, mean annual precipitation and frost-free periods were the most important variables. With inclusion of LiDAR-derived attributes, depth-to-water table, terrain-intercepted annual radiation, and elevation were most often selected. This suggests that fine-scale terrain conditions affect the distribution of the studied species more than canopy conditions.

Studies of Seeding Millet in Accurate Grooves and Holes Under Water-permeability Plastic Film

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Growth of Timber Rattlesnakes (Crotalus horridus) in an Agriculturally Fragmented and a Contiguously Forested Habitat

Habitat loss and fragmentation threaten Timber Rattlesnake (Crotalus horridus) populations in contiguous, mature forests of eastern North America, yet information regarding the life history of C. horridus in fragmented habitats is sparse. In this study, we used mark–recapture data on body size and rattle morphology to compare the size at birth and per ecdysis growth rates of C. horridus from a fragmented habitat in west-central Missouri (MO) with those from a closed-canopy forest in northwest Arkansas (AR). The MO population is typically exposed to a shorter frost-free period than the AR population, so individuals may have less time to acquire prey. At birth, snakes in the MO population were significantly shorter than those from AR, but MO snakes increased in length more rapidly than AR snakes through their first eight ecdyses. Sexual size dimorphism was apparent in the MO population when males and females diverged in size between the fifth and sixth ecdyses, whereas growth trajectories of AR males and females remained indistinguishable through the first eight ecdyses. Crotalus horridus in the agriculturally fragmented habitat may have grown faster than their forest-dwelling counterparts because fields and edges provide prey with stable food sources, unlike the boom and bust production typical of acorn mast crops. Although previous studies have demonstrated that C. horridus growth rates vary along latitudinal and elevational gradients due to climatic constraints on foraging, our study suggests that prey abundance may be just as important in shaping variation in life history both within and among populations.

Invertebrate drift in the piedmont part of the Kedrovaya River (Primorsky Krai, Russia) in warm season

Diurnal dynamics of invertebrate drift in the Kedrovaya River (Primorsky Krai, Russia), which flows in the zone of influence of the monsoon climate, has been studied. It has been shown that drifting invertebrates tend to shift from a predominantly daytime drift pattern to a distinguished nocturnal drift pattern during the frost-free period. The ratio of the total number of nighttime migrants to the total number of daytime migrants increased with every subsequent month. It has been proposed that the degree of light contrast between day and night can be significant in the regulation of nocturnal drift intensity.

Clinal variation in Pinus hartwegii populations and its application for adaptation to climate change

Abstract In order to determine the genetic variation among populations of Pinus hartwegii along altitudinal gradients, and the possible adaptive decoupling due to climatic change, a common garden test was set up with 13 provenances collected along an altitudinal transect (3150 to 3750 masl; collection sites were every 50 m of altitudinal difference) from Pico de Tancítaro, Michoacán, west-central Mexico. The test evaluated trees aged 4.5 to 5.5 years, and contemporary and future (year 2030; six model-emission scenarios) climate variables were estimated. We found significant (P&lt;0.005) differences among populations in total elongation, final seedling height, basal diameter, rate of elongation, dry weight of needles, branches and stem, total dry weight and first principal component. We found a significant association between population performance, expressed as first principal component values, and their climate, where the best climatic predictor was the frost free period (r2=0.90, P&lt;0.0001). This result indicates that the patterning of genetic differentiation among populations is strongly associated with a climatic and altitudinal gradient. We propose a re-delineation of fixed climatic and altitudinal seed zoning for seed and seedling movement, based on intervals of 26 days of difference of frost free period: Zone 1, from 240 to 214 days of frost free period or 12 to 11°C or 3150 to 3350 masl; Zone 2, 214 to 188 days or 11 to 10°C or 3350 to 3550 masl; and Zone 3, 188 to 162 days or 10 to 9°C or 3550 a 3750 masl. Projecting at what altitude will occur the same frost free period values by year 2030, we suggested that populations should be shifted 400 m attitudinally upward, through a program of assisted migration, aiming to realign the populations to the climate for which they are adapted. Seedling deployment should use future (year 2030) fixed seed zones, with the same projected climatic interval values than contemporary climate, although at the following altitudinal limits: Zone 12030, from 3550 to 3750 masl; Zone 22030, 3750 to 3950 masl; and Zone 32030, 3950 to 4150 masl.

Risk occurrences of damaging frosts during the growing season of vegetables in the Elbe River lowland, the Czech Republic

This study has, for the first time, analysed in detail the risk occurrences of the last spring frost, first fall frost and the length of the frost-free period during the growing season of vegetable crops at a high horizontal resolution of 10 km in the Elbe River lowland in the Czech Republic. The daily minimum air temperature from 116 grid points throughout the studied area for the period 1961–2011 was used. The daily values of minimum air temperature ranges of 0 to −1.1 °C, −1.2 to −2.2 °C and below −2.2 °C were considered to constitute mild, moderate and severe frost intensities, respectively. Firstly, the spatiotemporal variability of the date of the last spring frost, the date of the first fall frost and the length of the frost-free period in the Elbe River lowland is provided. Secondly, the estimation of the probability of a later date in the spring and an earlier date in the fall for various severe frost events and the length of the frost-free period is determined. Third, the changes in the timing of the last and first frosts of the three severities, as well as the length of the frost-free period, are evaluated. From 1961 to 2011, the Elbe River lowland has experienced a decrease in the number of frost days, while the length of the frost-free period between the last spring frost and the first fall frost has increased. The temporal evolution of the frost-free period anomalies displays two distinct periods: a shortening of the frost-free period in the 1960s and an intensified lengthening of the frost-free period since the 1980s. Whereas the latest spring frost has ended on an earlier date across the Elbe River lowland, the first frost date in the fall has generally been delayed to a later date. The dates of the last spring frost have advanced by −0.21 days per year on average. The fall dates are delayed up to 0.18 days per year, whereas the frost-free period is lengthening by up to 0.39 days per year on average. However, regional frost series suggests that the frost-free period exhibits a large amount of inter-annual variability. In terms of the growth of field vegetables, a late spring frost remains a risk factor, but the degree of risk has decreased. There is a 25 % chance of the occurrence of dangerous spring frosts during the planting of field vegetables after 3rd May, but after 15th May, the risk is only 10 %.