Frost Risk Research Articles

Minimum temperature mapping augments Australian grain farmers’ knowledge of frost

Economic losses due to crop damage caused by frost in Australia are estimated to be many hundreds of millions of dollars. In broadacre cropping, pre-sowing management to alleviate frost risk, and timely post-frost decisions rely on locally relevant information about the extent and severity of frosts. Yet temperature information currently available to grain farmers often has limited local relevance due to distance from meteorological stations. The availability of minimum temperature (Tmin) maps at an appropriate scale would facilitate improved farmer decision-making in response to frost risk and frost events.This study deployed temperature loggers and utilised Multivariate Adaptive Regression Splines (MARS) modelling to develop maps of Tmin at farm scale (30 × 30 m grid). We use terrain derived variables to generate nightly Tmin maps across a whole farm, based on data from a single on-farm weather station. Based on cross-validation, only elevation and elevation standard deviation were found to be useful predictors. Validation of the model against different years and locations resulted in good predictive RMSE values in the range 0.72 to 1.61°C. Classification accuracy scores (F1) for prediction of temperatures being above or below a 2°C threshold ranged from 83% to 96%.A priority of this work was to understand how the minimum temperature mapping complements farmers’ understanding of frost, and how it would contribute to improved management of frost in their cropping systems. Evaluation of the maps by farmers showed general agreement that the maps complemented local knowledge, with the main interest in the maps being as a guide to know where to start looking for frost damage.We have developed a method to generate Tmin maps based on a data from a single on-site temperature logger combined with terrain data and demonstrated that these maps are appropriately accurate and at a scale that is relevant to farmer management actions.

Photoperiod decelerates the advance of spring phenology of six deciduous tree species under climate warming.

Vegetation phenology in spring has substantially advanced under climate warming, consequently shifting the seasonality of ecosystem process and altering biosphere-atmosphere feedbacks. However, whether and to what extent photoperiod (i.e., daylength) affects the phenological advancement is unclear, leading to large uncertainties in projecting future phenological changes. Here we examined the photoperiod effect on spring phenology at a regional scale using in situ observation of six deciduous tree species from the Pan European Phenological Network during 1980-2016. We disentangled the photoperiod effect from the temperature effect (i.e., forcing and chilling) by utilizing the unique topography of the northern Alps of Europe (i.e., varying daylength but uniform temperature distribution across latitudes) and examining phenological changes across latitudes. We found prominent photoperiod-induced shifts in spring leaf-out across latitudes (up to 1.7days per latitudinal degree). Photoperiod regulates spring phenology by delaying early leaf-out and advancing late leaf-out caused by temperature variations. Based on these findings, we proposed two phenological models that consider the photoperiod effect through different mechanisms and compared them with a chilling model. We found that photoperiod regulation would slow down the advance in spring leaf-out under projected climate warming and thus mitigate the increasing frost risk in spring that deciduous forests will face in the future. Our findings identify photoperiod as a critical but understudied factor influencing spring phenology, suggesting that the responses of terrestrial ecosystem processes to climate warming are likely to be overestimated without adequately considering the photoperiod effect.

Climate risk services for cereal farming

Abstract. Agricultural production is largely determined by weather conditions during the crop growing season. An important aspect of crop yield estimation concerns crop growth development. The occurrence of meteorological events such as frosts, droughts or heat stress during the crop life cycle or during certain phenological stages helps explain yield fluctuations of common arable crops. We developed a methodology and visualisation tool for risk assessment, and tested the workflow for drought and frost risk for winter wheat, winter barley and grain maize in Belgium. The methodology has the potential to be extended to other extreme weather events and their impacts on crop growth in different regions of the world.

Observed changes in the agroclimatic zones in the Czech Republic between 1961 and 2019

The paper shows a large-scale shift in agroclimatic zones in the territory of the Czech Republic (CR) between 1961 and 2019. The method used for agroclimatic zoning took advantage of high-resolution (0.5 km × 0.5 km) daily climate data collected from 268 climatological and 787 rain-gauge stations. The climate information was combined with soil and terrain data at the same resolution. The set of seven agroclimatic indicators allowed us to estimate rates of changes in agroclimatic conditions over the 1961–2019 period, including changes in the air temperature regime, global radiation, drought, frost risks and snow cover occurrence. These indicators are relevant for all main crops and agroclimatic zoning and account for local soil and slope conditions. The study clearly highlights major shifts in the type and extent of agroclimatic zones between 1961–2000 and 2000–2019, which led to the occurrence of entirely new combinations of agroclimatic indicators.

Reduced frost hardiness in temperate woody species due to climate warming: a model-based analysis

The climate warming that has occurred over the past decades may benefit plant growth and development because it reduces the severity of frost events. However, these rising temperatures may also lead to diminished frost hardiness in plants due to their insufficient hardening. Despite climate warming exerting such dual effects on frost damage, how this might change the frost damage of woody plants remains unknown. Here, we conducted a laboratory experiment that used the relative electrolyte leakage method to derive species-specific model parameters for frost hardiness and a damage model. Then we simulated the daily frost hardiness and damage of five typical temperate tree species (Ulmus pumila, Robinia pseudoacacia, Fraxinus chinensis, Salix babylonica, and Armeniaca vulgaris), from 1980 to 2015, in Beijing, China. The root mean square error (RMSE) between observed and predicted frost damage ranged from 3.58% to 7.65%. According to our simulation results, frost hardiness has declined over this 36-year period due to insufficient cold hardening of plants in autumn coupled with rapid dehardening in spring; however, the percentage of frost damage incurred by the five species showed a declining trend because of the reduced frequency and intensity of frost events. Thus, decreased frost severity may, to a large extent, offset the negative effects of diminished frost hardiness such that the frost risk faced by temperate forests may well remain constant or decline with continued climate warming.

Open-air grape classification and its application in parcel-level risk assessment of late frost in the eastern Helan Mountains

The eastern Helan Mountains are one of the most important plantings and production bases for high-quality grapes in China. In winter, grape root is prone to freezing damage owing to natural phenomenon such as early and late frost, and methods to assess disaster risk at the grape parcel level is one of the current research hotspots. However, there are two problems at present; first is the lack of grape parcel maps and second is that scale of disaster risk assessment is limited to the level of administrative divisions and grid systems. Therefore, according to the perennial characteristics of the grapes and clear texture of the open-air grape parcels based on public data sets (Sentinel-2A/B) and high-quality winery address information, combined with Google Earth engine (GEE) platform, Google Earth, and Ovitalmap, this study designs a collection scheme of open-air grape parcel samples and non-grape parcel samples, analyzes the environmental characteristics of the distribution of high-quality wineries, constructs a classification feature database in three aspects (time, terrain, and vegetation), uses the random forest classification method to classify open-air grape parcels in the eastern Helan Mountains in 2019, and conducts a late frost disaster risk assessment of the open-air grape parcel. The results show that: (1) The high-quality wineries are mainly distributed in the elevation of 1106–1240 m, with the average slope of 0.82°, the organic matter content of 10.79–14.27 g/kg, the P content of 24.87–37.58 mg/kg, the K content of 116–166 mg/kg, the pH 8.38–8.55, N content of 0.65–0.98 g/kg, annual average active accumulated temperature ≥10 °C of 3490–3590 °C, annual average rainfall of 189–201 mm, the annual average sunshine duration of 7.3–7.6 h, annual average air temperature of 8.8–9.4 °C, annual average temperature difference of 12.7–13.2 °C, annual average frost-free period at 263–270 d and annual average relative air Humidity of 50–54%. (2) The overall classification accuracy of open-air grape parcels reached 98.96% and the verification accuracy of ground truth parcel samples reached 87.89%. The open-air grape parcels in the eastern Helan Mountains are mainly distributed in Helan County, Xixia District, Yongning County, and Qingtongxia City. (3) The highest risk of late frost was found in Xixia District and the lowest risk in Yongning County. Helan County was higher than Qingtongxia City in the medium risk of late frost. The typical small area high risk includes Liangtian Town, the experimental field of Ningxia Academy of Agricultural and Forestry Sciences in Zhenbeibao Town, Yuhuang Winery in Ganchengzi Village, and the State-run Warm Spring Farm in Helan County. Thus, the sample collection and augmentation scheme are feasible, the open-air grape classification accuracy is high and its result is consistent with field investigation, which can provide accurate parcel-level disaster risk assessment and provide decision support for agricultural departments and farmers.

Common‐garden experiment reveals clinal trends of bud phenology in black spruce populations from a latitudinal gradient in the boreal forest

Abstract Climate warming is modifying the movement of air masses over Northern latitudes, producing warming and cooling events across the boreal regions. These new conditions changes may mismatch plant phenology from weather conditions, and affect the growing period of trees. Understanding the processes of local adaptation in bud phenology can help to predict the response of plants to these rapid and unexpected environmental changes. Our study monitored bud burst and bud set weekly during four growing seasons in black spruce [Picea mariana (Mill.) B.S.P.] saplings planted in a common garden and originating from five provenances representing the whole latitudinal distribution of the closed boreal forest in Quebec, Canada. We compared the variance in bud phenology among populations and years, and analysed the relationships with temperatures at the origin sites. Bud burst and bud set occurred in mid‐May and mid‐July, respectively, with a large variability among provenances and between the study years. A delayed bud phenology was observed in the provenances from warmer sites, with bud burst and bud set being 1.1 and 1.4 days later for every additional degree in mean annual temperature at the origin site respectively. Populations with earlier bud bursts also showed earlier bud sets, thus the growing season was similar among provenances. The heritability of bud set was higher than that of bud burst, with estimates of 0.26 and 0.21 respectively. On average, variance in bud phenology among provenances reached 5.3%, which was higher than that within provenances (2.6%). The factor year explained 37.7%–69.7% of the variance in bud phenology. Synthesis. The findings demonstrate the evolutionary response to climate variations in the boreal biome. Endogenous and environmental components have different effects on the phases of bud burst and bud set. This complex interaction among drivers of bud phenology may prevent reliable predictions of changes in the growing season under changing climate. An earlier growth reactivation due to higher spring temperatures could result in higher frost risks to the developing buds. Despite a longer period for photosynthesis expected for the evergreen black spruce under warmer conditions, the period spent for bud development could remain unchanged.

Developing a satellite-based frost risk model for the Southern African commercial forestry landscape

Frost is a sporadic meteorological event affecting the productivity of commercial forests in South Africa. Severe frost occurrences may cause irreversible damage to forest stands, slowing down tree growth or leading to tree mortality. Using the Moderate Imaging Spectrometer (spatial resolution: 1 km by 1 km, swath: 1 200 km by 1 200 km) night-time land surface temperatures between 2002 and 2011, this study mapped frost risk classes using six satellite-derived variables at the landscape level. These variables included calculated thresholds of minimum temperature, probability of frost occurrence, mean temperature, total number of frost days, frost duration and the frost severity index. Results show that, using an unsupervised random forest approach with partitioning around medoids, clustering was successful in mapping frost risk using eight optimal clusters. The methodology developed in this study contributes to building a robust frost-risk model to manage and mitigate forest frost damage.

Assisted migration poleward rather than upward in elevation minimizes frost risks in plantations

When assisted migration is used to address climate change, tree seedlings may have to be moved to substantially colder environments in anticipation of climate warming over their life span. Here, we evaluate frost risks for four economically important forest tree species of western Canada, Douglas-fir (Pseudotsuga menziesii), lodgepole pine (Pinus contorta), interior spruce (Picea glauca, P. engelmannii, and their hybrids), and western larch (Larix occidentalis), when moved to adjacent northern and higher elevation seed zones that are cooler by approximately 2 °C. Changes to risks of damaging frosts among seed zones are evaluated during two 30-day periods, after dormancy release in spring and before onset of dormancy in fall, assuming a temperature-dominated day of bud break and a critical photoperiod-controlled onset of dormancy in fall. Based on daily interpolated climate data between 1980 and 2019, we find that late spring and early fall frost risks do not change significantly for transfers toward the north (<1 percentage point in most cases). In contrast, moving planting stock toward higher elevation generally leads to a substantial increase in exposure to unseasonal frosts (late spring frosts: 0.5% to 9.4%, early fall frosts: 0.8% to 17.1%). We conclude that transfers toward the north are preferable to transfers up in elevation in reforestation of these tree species in western Canada.

Dynamic modelling of cold-hardiness in tea buds by imitating past temperature memory.

Background and AimsMost perennial plants memorize cold stress for a certain period and retrieve the memories for cold acclimation and deacclimation, which leads to seasonal changes in cold-hardiness. Therefore, a model for evaluating cold stress memories is required for predicting cold-hardiness and for future frost risk assessments under warming climates. In this study we develop a new dynamic model of cold-hardiness by introducing a function imitating past temperature memory in the processes of cold acclimation and deacclimation.MethodsWe formulated the past temperature memory for plants using thermal time weighted by a forgetting function, and thereby proposed a dynamic model of cold-hardiness. We used the buds of tea plants (Camellia sinensis) from two cultivars, ‘Yabukita’ and ‘Yutakamidori’, to calibrate and validate this model based on 10 years of observed cold-hardiness data.Key ResultsThe model captured more than 90 % of the observed variation in cold-hardiness and predicted accurate values for both cultivars, with root mean square errors of ~1.0 °C. The optimized forgetting function indicated that the tea buds memorized both short-term (recent days) and long-term (previous months) temperatures. The memories can drive short-term processes such as increasing/decreasing the content of carbohydrates, proteins and antioxidants in the buds, as well as long-term processes such as determining the bud phenological stage, both of which vary with cold-hardiness.ConclusionsThe use of a forgetting function is an effective means of understanding temperature memories in plants and will aid in developing reliable predictions of cold-hardiness for various plant species under global climate warming.

Riscos de geadas em cultivos de batata na região de Guarapuava-PR em diferentes fases do ENOS

A condução de cultivos em condições de baixa previsibilidade da variabilidade climática pode ser considerado como um elemento de redução expressiva dos resultados de produção. A batata é definida como uma cultura sensível ao frio intenso, e no Sul do Brasil o ciclo de cultivo pode ocorrer em período de risco de eventos de geada. O estudo objetivou avaliar os riscos de ocorrência de geadas de diferentes intensidades durante o ciclo de desenvolvimento da cultura da batata em Guarapuava-PR, em diferentes períodos de cultivo nas distintas fases do ENOS. Utilizou-se série histórica de dados climáticos de 43 anos, entre 1976 e 2018. As análises foram realizadas com estatística descritiva utilizando-se índices de porcentagem e normalização de conjunto de dados. Os dados foram agrupados em períodos decendiais para os meses de agosto a outubro e março a maio, em que existe frequência de geadas e possibilidade de lavouras de batata em desenvolvimento no campo. Dentre os principais resultados verificou-se que o período de plantio, com minimização dos riscos de ocorrência de geadas para a cultura na região de Guarapuava, é compreendido entre 21 de setembro e 31 de janeiro em ambas as fases do ENOS, El Niño e La Niña e neutralidade climática. De forma geral o cultivo de batata em anos de neutralidade está sujeito à maiores riscos de perdas por ocorrência de geadas quando comparados com o plantio em anos de fenômeno El Niño e La Niña.

El Niño-Oscilação Sul e ocorrência de geadas na região de Guarapuava-PR

A associação das características das fases El Niño Oscilação Sul (ENOS) com as condições locais, são ferramentas importantes para serem empregadas na geração de informações inerentes aos riscos de geadas. Apesar do seu grande impacto na região Sul do Brasil e em outras partes do mundo, as geadas são eventos de difícil previsibilidade por serem resultado da interação de diferentes condições climáticas. Este estudo teve como objetivo analisar a ocorrência de geadas durante os anos de El Niño, La Niña e neutralidade na região de Guarapuava-PR. Foi utilizada uma base de dados históricos das variáveis climáticas de 43 anos (1976 a 2018) posteriormente cruzados com dados do ENOS obtidos da Nacional Oceanic and Atmospheric Administration (NOAA). Verificou-se que períodos de neutralidade climática são predominantes em relação as fases extremas do ENOS e apresenta maior frequência de eventos de geadas. Nesta condição a frequência de geadas é de 67% em relação 20% e 13% em La Niña e El Niño, respectivamente.

Advancing frost dates have reduced frost risk among most North American angiosperms since 1980.

In recent decades, the final frost dates of winter have advanced throughout North America, and many angiosperm taxa have simultaneously advanced their flowering times as the climate has warmed. Phenological advancement may reduce plant fitness, as flowering prior to the final frost date of the winter/spring transition may damage flower buds or open flowers, limiting fruit and seed production. The risk of floral exposure to frost in the recent past and in the future, however, also depends on whether the last day of winter frost is advancing more rapidly, or less rapidly, than the date of onset of flowering in response to climate warming. This study presents the first continental-scale assessment of recent changes in frost risk to floral tissues, using digital records of 475,694 herbarium specimens representing 1,653 angiosperm species collected across North America from 1920 to 2015. For most species, among sites from which they have been collected, dates of last frost have advanced much more rapidly than flowering dates. As a result, frost risk has declined in 66% of sampled species. Moreover, exotic species consistently exhibit lower frost risk than native species, primarily because the former occupy warmer habitats where the annual frost-free period begins earlier. While reducing the probability of exposure to frost has clear benefits for the survival of flower buds and flowers, such phenological advancement may disrupt other ecological processes across North America, including pollination, herbivory, and disease transmission.

Modelling phenology to probe for trade-offs between frost and heat risk in lentil and faba bean

Extreme temperatures at critical developmental phases reduce grain yield. Combinations of sowing date and cultivar that favour faster development reduce the likelihood of heat stress but increase the risk of frost at critical phases. Current models are unable to predict pulse yield in response to frost and heat, hence our focus on phenology. Our aim was to model phenological variation with sowing date and cultivar for lentil and faba bean against the climatic patterns of frost and heat in 45 Australian locations that spanned 29 °S-41 °S, 11−340 m.a.s.l., and 1−423 km to the coast.For both crops, modelled mean and standard deviation of time to flowering were close to actuals and mean prediction error was below 5%. Comparison of actual and modelled time to flowering returned: r = 0.89 (n = 121, P < 0.0001) and modelling efficiency = 0.73 for lentil, and r = 0.96 (n = 123, P < 0.0001) and modelling efficiency = 0.84 for faba bean.The critical period for yield determination was assumed to span from flowering to 200 °Cd after flowering. Curves fitted to the time-course of frost (< 0 °C) and heat (> 34 °C) probabilities between 1957 and 2018 were used to estimate the date of 10 % frost probability and the date of 30 % heat probability as the boundaries of a frost-heat risk window for the critical period. Out of the 45 locations, 12 were frost-free but with risk of heat, 7 were heat-free but with risk of frost, 3 were frost- and heat-free, and 23 featured a window defined by both frost and heat boundaries. Frost variables discriminated locations more strongly than heat variables. Geographical patterns in thermal regimes emerged that were associated with latitude, altitude and continentality.Realised warming between 1957 and 2018 advanced the time to 200 °Cd after flowering and shortened the critical period in most locations, particularly in early-sown crops. Comparisons of the probability curves of frost and heat between 1957–1985 and 1986–2018 showed, with few exceptions, an asymmetry between delayed late frost (up to 44 d) and earlier heat onset (up to 11 d), with a narrowing of the frost-heat risk window from 46 to 90 d for the period 1957–1985 to 34–64 d for 1986–2018.We identified a dominant role of frost as (i) the main discriminating factor among geographically distinct locations, (ii) the main source of variation of the frost-heat window, and (iii) a putatively increased risk factor with climate change. Adaptation to frost in the critical period for yield is important for pulses despite warming trends. Increased frost tolerance can directly improve yield and indirectly contribute to reduce risk of heat and drought later in the season.

AGROCLIMATIC RISK ZONING OF PASSION FRUIT (Passiflora edulis Sims) IN THE HYDROGRAPHIC BASIN OF PARANÁ RIVER III, BRAZIL

Brazil is the largest producer and consumer of passion fruit in the world. Fruticulture is a prominent segment of Brazilian agriculture. Despite recent technological and scientific advances, the climate is among the most important variable in crops productions. In this context, agroclimatic zoning should be one of the first information to consider before starting the cultivation of a particular crop. The purpose of this paper was to perform agroclimatic risk zoning for passion fruit (Passiflora edulis Sims) in the basin of Parana river 3, located in Parana state, South of Brazil. For this we used meteorological data from 43 stations with historical series between from 1976 to 2019. The analysis of agroclimatic risk was based on the species requirements, such as rainfall, annual water deficit, annual average temperature, sunshine and the risk of frost. The occurrence of frost was the most limiting factor for production in the region. This meteorological factor restricted planting in the central-eastern portion of the basin. In other areas, the risk is present, however the suitability for the passion fruit planting was guaranteed.

CLIMATE ZONING FOR THE CULTIVATION OF AFRICAN MAHOGANY SPECIES IN BRAZIL

African mahogany is the common name given to different species of the genus Khaya. They are tree species native to the African continent, which have a wood quality that allows their noble use in making fine furniture, and in the civil and naval industries. Currently, African mahogany cultivation has received notoriety in Brazil and given its climatic conditions. The country has great potential for planting these species. The purpose of this work was to identify climatic aptitude zones for African mahogany in Brazil. Based on the Kppen classification and in the means of relative air temperature and annual rainfall, a base map interpolation was performed to select regions suitable and restricted to planting and adequate growth of African mahogany species. In general, the regions that presented temperatures between 22 °C and 30 °C were considered of high fitness, while temperature values below 14 °C restricts plantations growth. Regarding to precipitation, areas considered to be of high aptitude have between 700 to 3,000 mm.year-1, extreme values may indicate regions of low suitability and restricted to the cultivation of African mahogany. From the climatic characteristics, it was determined that about 60% of the Brazilian area was of high fitness, between 16% and 32% of medium fitness, and less than 20% as low fitness. The Northeastern semi-arid region proved to be restricted to the cultivation of these species due to the low annual rainfall and a few places in the South region was also restricted due to low temperatures and risks of frost.

Geoinformation modeling of the spatial distribution of the favourability level of climatic resources over the Sevastopol region for grape growing

Viticulture is one of the promising agricultural sectors in the Sevastopol region. In connection with this the goal of the work is a comprehensive analysis of the climatic conditions of the region for the rational distribution of vineyards. Meteorological data (air temperature and precipitation) for the period 1985-2018 and terrain parameters (slope, aspect, altitude) for the Sevastopol region were used. To assess the optimal climatic conditions, the analysis of frost risk, heat supply and water supply (average of absolute minimums of air temperature, growing degree days, Selianinov’s Hydrothermal Coeffi cient, Huglin and Winkler indices) was carried out. The spatial distribution of the listed agroclimatic parameters was modeled using author formulas. Using GIS technologies, maps of the spatial distribution of heat supply and agroclimatic parmeters for the region were obtained. The main part of the territory of the Sevastopol region is located in a zone with a sum of active temperatures of 3500-3900°С. The amount of precipitation during the growing season and the values of the hydrothermal coeffi cient indicate insuffi cient moisture in the region. Most of the region’s territory (72 %) has an average of absolute minimums of air temperature above –14 °C. According to the values of the Huglin index, the main part of the region is in the warm zone (2400-2700 °C), and by the values of the Winkler index – in Region 3 (1667-1944 °C). The heliothermal conditions of the Sevastopol region territory are suffi cient for growing grapes of diff erent groups of varieties and ripening dates. Agroclimatic parameters are characterized by positive trends, which in the future can lead to changes in heat supply and the displacement of terroirs. The territory of the Sevastopol region has favourable agroclimatic conditions, which makes it possible to grow grape varieties from very early to late ripening and placing them on fl at and sloping lands.

Frost Monitoring Cyber–Physical System: A Survey on Prediction and Active Protection Methods

Frost damage in broadacre cropping and horticulture (including viticulture) results in substantial economic losses to producers and may also disrupt associated product value chains. Frost risk windows are changing in timing, frequency, and duration. Faced with the increasing cost of mitigation infrastructure and competition for resources (e.g., water and energy), multiperil insurance, and the need for supply chain certainty, producers are under pressure to innovate in order to manage and mitigate risk. Frost protection systems are cyber-physical systems (CPSs) consisting of sensors (event detection), intelligence (prediction), and actuators (active protection methods). The Internet-of-Things communication protocols joining the CPS components are also evaluated. In this context, this article introduces and reviews existing methods of frost management. This article focuses on active protection methods because of their potential for real-time deployment during frost events. For integrated frost prediction and active protection systems, prediction method, sensor types, and integration architecture are assessed, research gaps are identified and future research directions proposed.

AGROCLIMATIC RISK ZONING FOR GUAVA (Psidium guajava L.) IN PARANÁ RIVER BASIN 3

Fruticulture constitutes an important sector of the Brazilian agricultural industry. Despite technological and scientific advances, climate is still the most important variable defining crop productivity. Because of this, agroclimatic zoning should be one of the first factors to consider when starting to plant a particular crop. The objective of this work was to conduct climate risk zoning for guava (Psidium guajava L.) in Paraná river basin 3, Paraná, Brazil, using meteorological data from 43 stations collected between 1976 and 2018. The climate risk analysis was based on the climatic factors that impact the species, such as rainfall, annual water deficit, average annual temperature, coldest month temperature, and risk of frost. The findings of this study suggest that the basin has areas with a low climate risk for guava cultivation. Precipitation and water balance were sufficient under all tested scenarios. The most limiting factor for production was frost, but with risk only present during the first years of cultivation. Despite this, planting restrictions were only predicted to occur in the far west portion of the basin. Agricultural techniques that reduce the risk of frost and avoiding areas with greater frost incidences are the two most important aspects to consider to ensure greater success for guava in the region.

Lowest drought sensitivity and decreasing growth synchrony towards the dry distribution margin of European beech

AbstractAimClimate limits the potential distribution ranges of species. Establishment and growth of individuals at range margins is assumed to be more limited by extreme events such as drought or frost events than in the centre of their range. We explore whether the growth of beech is more sensitive to drought towards the dry distribution margin and more sensitive to frost towards the cold distribution margin. Furthermore, we aim to gain insight into the adaptive potential of beech towards both the dry and cold distribution margins.LocationEuropean gradient from the dry (Spain) to the cold (Poland, Sweden) distribution margin of beech.TaxonEuropean beech (Fagus sylvatica L.).MethodsWe applied a range‐wide dendroecological study to analyse spatial and temporal trends in climate–growth relationships. We further investigated negative growth anomalies and growth synchrony towards the range margins.ResultsWe found beech to be drought sensitive across its whole range, except at the dry distribution margin. Furthermore, sensitivity to winter temperature was not found in the centre or at the cold distribution margin, but at the southern distribution margin. Growth synchrony was lower at the dry than at the cold distribution margin.Main conclusionsBeech seems to be adapted to drought at the dry distribution margin with a high adaptive potential indicated by the lowest growth synchrony along the gradient. At the cold distribution margin, cold events in winter and spring were less important for growth than drought. Still, the importance of spring frost for beech growth appears to increase in recent decades. Considering a projected north‐eastward shift of the distribution range, beech is likely facing drought stress in combination with spring frost risk at the cold margin which could lead to a hampered range expansion.