Phenological variability and resistance to late spring frost of common beech in the international provenance test in Bosnia and Herzegovina

The research aimed to determine the start, end and duration of leafing phases, the degree of plant damage caused by late spring frost, and the retention of leaves in autumn. The research was conducted in the international common beech provenance test in Bosnia and Herzegovina. The test contains eight provenances from Bosnia and Herzegovina, four from Germany, three from Serbia, two each from Croatia, Romania and Switzerland, and one from Hungary. Leafing phenology, canopy damage caused by late spring frost, and leaf retention were assessed in 2019. Most provenances started opening buds on 17 April 2019. Complete canopy damage affected the highest percentage of plants in provenance BW Bad Wildbad, Germany (68 %), and the lowest in provenance Konjuh Kladanj, Bosnia and Herzegovina (3.2 %). Provenance Herzogenbuchsee from Switzerland had the highest percentage of winter leaf retention (37.5 % of plants). The results can be used in choosing provenances that are resistant to low temperatures in zones of late spring and early autumn frost.

Growth Recovery and Phenological Responses of Juvenile Beech (Fagus sylvatica L.) Exposed to Spring Warming and Late Spring Frost

Global change increases the risk of extreme climatic events. The impact of extreme temperature may depend on the tree species and also on the provenance. Ten provenances of Fagus sylvatica L. were grown in a common garden environment in Belgium and subjected to different temperature treatments. Half of the one year old seedlings were submitted to a high thermal stress in the spring of the first year, and all plants were exposed to a late spring frost in the second year. The high-temperature treated plants displayed reduced growth in the first year, which was fully compensated (recovery with exact compensation) in the second year for radial growth and in the third year for height growth. Frost in the spring of the second year damaged part of the saplings and reduced their growth. The frost damaged plants regained the pre-stress growth rate one year later (recovery without compensation). The high temperature treatment in the first year and the frost damage in the second year clearly influenced the phenological responses in the year of the event and in the succeeding year. Little population differentiation was observed among the provenances for growth and for phenological responses. Yet, a southern provenance, a non-autochthonous provenance (original German provenance that was planted in Belgium about a century ago) and a more continental provenance flushed earlier than the local Atlantic provenances in the year of the frost event, resulting in more frost damage. Some caution should therefore be taken when translocating provenances as an anticipation of the predicted climate warming.

Sensitivity of Winter Barley Yield to Climate Variability in a Pleistocene Loess Area

Global climate change is predicted to increase temperatures and change the distribution of precipitation. However, there is high uncertainty regarding the regional occurrence and intensity of climate change. Therefore, this work examines the effects of climate parameters on the long-term yields of winter barley and assesses the parameters affecting plant development throughout the year and in specific growth phases. The investigation was carried out in an area with Pleistocene loess, a highly fertile site in Germany. The effect of climate on crop yields was modeled with monthly weather parameters and additional indices such as different drought parameters, heat-related stress, late spring frost, early autumn frost, and precipitation-free periods. Residuals and yield values were treated as dependent variables. The residuals were determined from long-term yield trends using the autoregressive integrated moving average (ARIMA) method. The results indicated that temperature and precipitation are significant in all calculations in all variants, but to a lesser degree when considered as sums or mean values, compared with specific indices (e.g., frost-alternating days, the temperature threshold, the precipitation intensity, rain-free days, the early/late frost index, and the de Martonne–Reichel dryness index). The inter-annual variations in crop yields were mainly determined by the prevailing climatic conditions in winter as well as the transition periods from the warmer season to winter and vice versa. The main winter indices were the temperature threshold, frost-alternating days, and precipitation intensity. During the main growth periods, only the precipitation intensity was significant. These findings can be attributed to the high available field water capacity of this site, which overcomes the need for summer precipitation if the soil water storage is replenished during winter.

Process-Based Indicators for Timely Identification of Apricot Frost Disaster on the Warm Temperate Zone, China

Frequent occurrences of extreme cold weather processes create severe agricultural/forest frost events, even given the background of global warming. In the warm temperate zone of China, which is the largest planting area for fresh apricot, late spring frost disaster has become one of the major meteorological hazards during flowering. To prevent cold weather-induced apricot frost events and reduce potential losses in related fruit economic value, it is vital to establish a meteorological indicator for timely and accurate identification of cold weather process-based apricot frost events, to provide support for timely apricot frost monitoring and warning in late spring. In this study, daily minimax temperature (Tmin) and apricot frost disaster data during flowering were combined to establish meteorological identification indicators of apricot frost based on cold weather processes. A process-based apricot frost model (f(D,Tcum) was firstly constructed, and characteristics of (Tcum) (accumulated harmful temperature) were explored under different D (duration days) based on the representation of historical apricot frost processes. Thresholds for the (Tcum) for apricot frost in 1, 2, 3, 4 and more than 5 days of apricot frost process were determined as -1.51, -2.92, -4.39, -5.84 and − 7.31°C, respectively. Validation results by reserved independent disaster samples were generally consistent with the historical records of apricot frost disasters, with 89.00% accuracy for indicator-based identification results. Typical process tracking of the proposed identification indicator to an apricot frost event that occurred in North Hebei during April 3–9, 2018 revealed that the indicator-based identification result basically coincides with the historical disaster record and can reflect more detailed information about the apricot frost process.

Shifts in the frequency of sequentially occurring late-spring frost and drought impact the dynamics of non-structural carbohydrates in European beech

<p>In the past, terrestrial ecosystems have largely functioned as carbon sinks, capturing nearly 30% of anthropogenic carbon dioxide emissions (Le Quéré et al. 2009). Forest ecosystems, which cover roughly 30% of the land surface, play a fundamental role in maintaining this sink by storing nearly half of all terrestrial carbon (Pan et al. 2011; Bonan 2008). Over large parts of Europe, these forest ecosystems are dominated by European beech. Consequently, the reaction of beech to climate extremes is central to the ability of European forests to act as carbon sinks. Disconcertingly, the projected – and indeed already observed – increase in frequency and severity of drought across Europe threatens to shift forest ecosystems from carbon sinks to carbon sources (Ciais et al. 2005). Concurrently, the incidence of late-spring frost events in Europe is on the rise. While these events are considerably more localized and do not result in the same widespread reduction of ecosystem productivity as droughts, the damage to the photosynthetic apparatus of affected trees forces the mobilization of non-structural carbohydrates (NSC) to ensure tree survival. We analyze high-resolution historical (E-OBS 0.1°) and projected (EURO-CORDEX RCP 2.6 & RCP 8.5 0.11°) climate data to identify localized changes in the frequency of sequentially occurring drought and late-spring frost events across Europe. Subsequently, we use a modified version of the standalone NSC-model SUGAR (Jones et al. 2020) to ascertain the effect of sequentially occurring climate extremes on the carbon reserves of European beech forests. Here, we identify differences in the impact of isolated extremes (either frost or drought) and sequential extremes (frost followed by drought and vice versa) on the regulation of the NSC pool. Through the integration of SUGAR with the LPJ-GUESS DGVM (Smith et al. 2014; Sitch et al. 2003) we further quantify the effect of sequentially occurring climate extremes on the productivity of beech forest ecosystems in central Europe.</p><p> </p>

Meteorological considerations of grapevine damage due to temperature variations: the 2019 late spring frost and summer heat wave events in Burgundy

<p><strong><span>Meteorological considerations of grapevine damage due to temperature variations:</span> <span>t</span><span>he 2019 late spring frost and summer heat wave events </span>in Burgundy </strong></p><p>During 2019, <span>the occurrence of two contrasting weather events, a cold snap and a heat wave, caused extensive damage to the vineyards</span> of Northern Burgundy. <span>The late spring cold snap, that </span><span>occurred</span><span> from May 5</span><sup><span>th</span></sup><span> to 7</span><sup><span>th</span></sup><span>, generated frost like conditions across the northern and north-western areas of the Côte-d'Or department.</span> The weather stations of the Northern Auxois area, where the three observation and study sites are located, recorded minimum temperatures <span>ranging </span>between -1 and -2°C. <span>On the 24</span><sup><span>th</span></sup><span> and the 25</span><sup><span>th</span></sup><span> of July vineyards were exposed, yet again, to an extreme temperature variation.</span> <span>A brief but unusually intense heat wave increased daily maximum temperatures up to 42°C in the department’s far north. Landforms such as plateaus were less exposed to the increase in temperatures due the limiting effect of higher elevations. This led to temperatures not exceeding 40°C above 300 m, elevation at which the vineyard sites of this study are located.</span></p><p>Weather conditions that caused the early May frost event were related to a northern circulation <span>present </span>over Western Europe <span>that persisted </span>from <span>the 28</span><sup><span>th</span></sup><span> of April </span><span>to</span><span> the 6</span><sup><span>th</span></sup><span> of May</span>. <span>The strong anticyclonic ridge stretching from Greenland to the Iberian Peninsula directed an air mass of arctic origin towards France.</span> <span>On July 24</span><sup><span>th</span></sup><span> and 25</span><sup><span>th</span></sup><span>, the presence of a surface high pressure system above Scandinavia, associated with a low-pressure center located near the Atlantic Ocean, generated an influx of a very hot air mass from the northern part of the African continent through France and neighbouring countries.</span></p><p>The local impact of these two weather events was modulated by the topographical features specific to the study area: a limestone plateau strongly dissected by parallel valleys <span>of S.E. / N.W. orientations</span>. <span>The three observation sites have similar soil characteristics and are located on south facing slopes.</span> <span>However, damage to vegetation was uneven across sites as well as within each site.</span> These observations rise up the question of the influence of very fine-scale environmental conditions <span>and the impact they might have on the different vegetative growth stages.</span> <span>Lastly, the variation in physiological response among grapevines and its effect on their sensitivity to the occurrence of different weather hazards is also to be considered.</span></p>

Changes in the Occurrence of Late Spring Frost in Poland

Trends in the appearance of the last spring frost for three thresholds of minimum daily air temperature at the height of 2 m and near the ground were examined for six meteorological stations located in two agricultural regions in Poland. For most time series, the last spring frost, calculated as a consecutive day of the year, showed a statistically significant trend indicating its earlier appearance from 1.6 to about 3.5 days per decade. The date of the last spring frost was also calculated in relation to the ongoing growing season. In this case, few statistically significant changes in the dates of the last frosts were found. The probability of the last spring frost on a specific day of the calendar year and the day of the growing season was also examined for two periods: 1961–1990 and 1991–2020. For low probability levels corresponding to the early dates of the last spring frost, the last frost usually occurred much earlier (6–14 days) in 1991–2020. With the probability levels of 80–90% describing the late occurrence of the last frost with a frequency of once every 5–10 years, at some stations, the last spring frosts occurred at a similar time for both periods.