•The Czech Republic has become an epicentre of bark beetle outbreaks in Europe.•We identified the transition from wind- to drought-driven outbreak dynamics.•The outbreak triggered a cascade of social ...impacts restricting management operations.•Effective responses require fundamental changes in the regional forest-based sector.
Outbreaks of tree-killing insects are intensifying globally, affecting economies, human well-being, and driving ecosystem transitions. The Czech Republic has recently become Europe’s epicenter of the outbreak of spruce bark beetle Ips typographus, the most aggressive species in Eurasia. We investigated a countrywide outbreak dynamic during the period 2003–2019, with a special focus on the period 2017–2019 when the outbreak reached an unprecedented intensity. In order to identify main outbreak drivers, we investigated annual time series of the volume of trees killed by bark beetles in the Czech districts (n = 77), and a suite of climatic and forest structure-related predictors using Generalized Additive Models. Finally, we reviewed a large body of public materials to understand broader social, ecological, and economic implications of the outbreak.
We found that bark beetles were damaging 0.2–1.4% of Norway spruce growing stock annually across the Czech Republic in the period 2003–2016. This level increased to 3.1–5.4% in 2017–2019, causing the total depletion of spruce in some regions. The long-term bark beetle dynamics (2003–2019) was driven by the combination of wind disturbance and climatic drivers, represented in our study by annual temperature anomaly and Standardized Precipitation-Evapotranspiration Index. However, the effect of wind was diminished during the period 2017–2019, whereas the effect of drought dominated. Our findings thus suggest a transition from wind- to drought-driven bark beetle dynamics.
The outbreak and subsequent large-scale salvaging and wood transportation affected quality of life of people in a broad vicinity of outbreak areas. Extensive management actions aggravated some of the notorious conflicts between forest management and nature conservation, and highlighted the poor harmonization of respective policies. A decrease in timber price, an excessive workload, and other cascading effects caused severe revenue loss, requiring state interventions amounting to ca 260 million EUR in 2018–2019.
We suggest that increasing frequency of climate extremes in combination with the unfavorable forest structure pushed Central European spruce forests to the margin of their ecological space and unfolded large-scale forest transformations. Effective responses will require fundamental structural changes in the regional forest-based sector, particularly aiming at increased social and ecological resilience.
VALUE is an open European collaboration to intercompare downscaling approaches for climate change research, focusing on different validation aspects (marginal, temporal, extremes, spatial, ...process‐based, etc.). Here we describe the participating methods and first results from the first experiment, using “perfect” reanalysis (and reanalysis‐driven regional climate model (RCM)) predictors to assess the intrinsic performance of the methods for downscaling precipitation and temperatures over a set of 86 stations representative of the main climatic regions in Europe. This study constitutes the largest and most comprehensive to date intercomparison of statistical downscaling methods, covering the three common downscaling approaches (perfect prognosis, model output statistics—including bias correction—and weather generators) with a total of over 50 downscaling methods representative of the most common techniques.
Overall, most of the downscaling methods greatly improve (reanalysis or RCM) raw model biases and no approach or technique seems to be superior in general, because there is a large method‐to‐method variability. The main factors most influencing the results are the seasonal calibration of the methods (e.g., using a moving window) and their stochastic nature. The particular predictors used also play an important role in cases where the comparison was possible, both for the validation results and for the strength of the predictor–predictand link, indicating the local variability explained. However, the present study cannot give a conclusive assessment of the skill of the methods to simulate regional future climates, and further experiments will be soon performed in the framework of the EURO‐CORDEX initiative (where VALUE activities have merged and follow on).
Finally, research transparency and reproducibility has been a major concern and substantive steps have been taken. In particular, the necessary data to run the experiments are provided at http://www.value‐cost.eu/data and data and validation results are available from the VALUE validation portal for further investigation: http://www.value‐cost.eu/validationportal.
The largest and most comprehensive to date intercomparison of statistical downscaling methods is presented, with a total of over 50 downscaling methods representative of the most common approaches and techniques. Overall, most of the downscaling methods greatly improve raw model biases and no approach is superior in general, due to the large method‐to‐method variability. The main factors influencing the results are the seasonal calibration of the methods and their stochastic nature, for biases in the mean and variance.
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•Polymers exhibit both lower and upper critical solution temperatures.•Limit temperatures can be easily adjusted by grafts length and grafting density.•Polymer behavior is ...additionally dependent on the concentration of potassium ions.•Polymers are useful in applications requiring thermo- and potassium-responsivity.
Novel multiresponsive hybrid biocompatible systems of κ-carrageenan-graft-poly(2-isopropyl-2-oxazoline-co-2-butyl-2-oxazoline)s with unique combination of responsiveness to external stimuli were synthesized and studied. The polymer thermoresponsive behavior proved the existence of both lower and upper critical solution temperatures in aqueous milieu, forming gel at lower temperature, a solution at room temperature and cloudy nanophase-separated dispersion at elevated temperature. The limit temperatures can easily be adjusted by the polyoxazoline graft length and grafting density. Moreover, the polymer behavior is additionally dependent on the concentration of potassium ions. The polymers behave similarly as the original κ-carrageenan, and thus, the poly(2-alkyl-2-oxazoline) grafts do not decrease the ability of the κ-carrageenan to form the self-assembled structures. Molecular principles beyond this multistimuli-responsive behavior were elucidated with the use of dynamic light scattering, magnetic resonance and fluorescence measurements as well as atomic force microscopy. These polymers could be used in a wide range of biological applications demanding thermo- and potassium-responsiveness.
Abstract
In the construction industry, FRP (fibre-reinfoced-polymer) reinforcement is used mainly because of its high resistance to aggressive environments. The production and design of straight FRP ...rebars are now very well understood and described. However, when designing concrete elements, it is usually necessary to adapt the reinforcement to the structure shape and to use bent rebars. However, during the production process, unfavourable changes in the fibre distribution across the cross-section may occur at the bent section. It has a significant effect on the short and long-term properties of the rebar. The paper addresses the highly topical issue of the composition, manufacturing and testing of shaped composite rebar. Consequently, the article presents experimentally determined values of mechanical characteristics obtained from the performed tests.
The timing of maturity of grapes depends on the weather conditions during the growing season. This study relies on the dependence of harvest dates on the air temperature and dry/wet conditions. ...Recorded observations show that increases in air temperature and dryness are associated with earlier grape harvests. Documentary data of grape harvests from the Bohemian wine-growing region (mainly northwest of Prague) were combined with mean Standardized Precipitation Evapotranspiration Index (SPEI) series starting in 1841 and ordinary least square regression with subsequent scaling to reconstruct the mean SPEI values for this area for April to August from 1499 to 2012. The reconstructed SPEI series explains 75% of the drought variability since 1841. All dry years that were detected by the reconstructed April–August SPEI values correlate well with years of excellent and good red wine of vintage quality for 1499–1840. A comparison of the reconstructed series with other SPEI reconstructions from the Czech Lands (the recent Czech Republic) based on documentary and instrumental data shows good agreement. The results demonstrate that grape harvest series may be used as a proxy for drought reconstruction in the central European region.
Europe is, after Asia, the second largest producer of wheat in the world, and provides the largest share of barley. Wheat (and to a similar extent, barley) production in Europe increased by more than ...6-fold during the 20th century. During the first half of the 20th century, this was driven by expanding the harvested area. This was followed, from the mid-20th century, by a massive increase in productivity that in many regions has stalled since 2000. However, it remains unclear what role climatic factors have played in these changes. Understanding the net impact of climatic trends over the past century would also aid in our understanding of the potential impact of future climate changes and in assessments of the potential for adaptation across Europe. In this study, we compiled information from several sources on winter wheat and spring barley yields and climatological data from 12 countries/regions covering the period from 1901−2012. The studied area includes the majority of climatic regions in which wheat and barley are grown (from central Italy to Finland). We hypothesized that changes in climatic conditions have led to measurable shifts in climate−yield relationships over the past 112 yr, and that presently grown wheat and barley show a more pronounced response to adverse weather conditions compared to crops from the early 20th century. The results confirm that climate−yield relationships have changed significantly over the period studied, and that in some regions, different predictors have had a greater effect on yields in recent times (between 1991 and 2012) than in previous decades. It is likely that changes in the climate−yield relationship at the local level might be more pronounced than those across the relatively large regions used in this study, as the latter represents aggregations of yields from various agroclimatic and pedoclimatic conditions that may show opposing trends.
This study quantified the crop water consumption, crop-specific irrigation requirements, and availability of water resources to catchments under climate change in the Czech Republic (CZ). Within the ...SoilClim model and BILAN-WATERES hydrological water balance modeling process, we tried to answer the question of whether there are at least theoretical water resources in the individual catchments of the CZ that could cover possible higher demands for irrigation. An ensemble of five global climate models under the moderate representative concentration pathway (RCP4.5) from the EURO-CORDEX initiative was chosen to project the future water use indicators. The irrigation water requirement indicators for the growing season (GS) of vineyards, hop gardens, orchards, vegetables, and fodder crops were calculated in 1143 catchments for two periods, 2031–2050 (Sc1) and 2061–2080 (Sc2), compared to the observed period 1961–2020 (Obs). To project irrigation scenarios in agricultural water management, the following water use indicators were quantified: relative soil moisture at 0–40 cm (AWR1) and 0–100 cm (AWR), crop water balance (Rain-ETa), irrigation water requirement (Irrig), and the ratio of actual and reference evapotranspiration (ETratio). To assess areas with a critically low water supply and quantify the frequency of water deficit during the GS of each crop, we calculated the number of days with extreme values of water use indicators. Quantification of the extreme irrigation characteristics reflected the highest depletion of soil moisture and the highest water demands, i.e., when the assessed indicators reached the 25th percentiles. For highly marketable vegetables, the largest deficit in Rain-ETa during the GS for Sc1 was projected. If current vegetable growing areas and cropping systems remain unchanged, Irrig will increase by 10.2% by the end of the 21st century under RCP4.5. Although current potato planting areas have soils with a high available water capacity, they will become controlled by the water deficit over the next few decades. The accumulated vineyard water required suggests that 15% and 25% of irrigation water will be lost by evaporation from the soil surface during the 2030s and 2080s, respectively. However, changes in future hopyard irrigation extent and amounts may have important implications in largely cropped irrigation hotspots. In the main traditional hop region for the 2030s, we project a 25% depletion of soil moisture and an increase of ETratio< 0.4 by up to 5.3%. The projection of a high frequency of days with an ETratio< 0.4 and AWR1 < 30% for fodder crops was related to the most risk-prone areas with an extreme lack of moisture in the regions with the most developed animal production. Thus, there will be insufficient fodder supply to the livestock sector due to any water stress during the production season under climate change conditions.
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•Over the 2030s, the increased irrigation water requirements would be larger in hopyards, orchards, vineyards, and fodder.•For orchards show an increase in the irrigation requirement by 14.5% in the 2030s and 10.2% in the 2080s.•For hopyards, irrigation requirements would change by 25% in the 2030s.•The irrigation requirements for vineyards would increase by 8.2% in the 2030s and 4.4% in the 2080s.•Growing vegetables with supplemental irrigation would be expected in 33% of catchments.
ABSTRACT
Central Europe is generally not considered a drought‐prone region compared with, for example, the Mediterranean. However, Central Europe, including the Czech Republic, recently experienced a ...series of drought events with substantial impacts, especially on crop production. Because agriculture systems, and vegetation in general, have adapted to evenly distributed precipitation, the region is susceptible to even short‐term droughts. The recent drought events may be the result of multi‐decadal climate variability or a more general trend, with some studies showing a link to a more frequent occurrence of atmospheric circulation patterns that are conducive to drought. This study introduces an innovation to the standard methodological approaches in evaluating drought climatology by analysing soil moisture conditions over more than 50 years. This approach relies on state‐of‐the‐art observed weather data and state‐of‐the‐art soil moisture model data, and focuses on the dynamic simulation of soil moisture content with high temporal (daily) and spatial (500 m) resolution in a diverse landscape. Statistically significant trends of decreasing soil moisture content were found, notably during May and June between 1961 and 2012. In contrast, trends towards higher soil moisture content were noted during the October–March time period. When the periods of 2001–2012 and 1961–1980 were compared, the probability of drought between April and June was found to increase by 50%. This indicates a loading of the ‘climate dice’ towards drier conditions. The probability of extreme drought events has also been found to increase. These results support concerns about the potentially increased severity of drought events in Central Europe under projected climate change.
Fiber reinforced polymer (FRP) rebars have increasing popularity in the construction industry all around the world although steel rebars are widely used for reinforcing of the concrete so far. FRP ...bars, which have higher tensile strength compared to steel rebars with the same nominal diameter under normal conditions, are composed of resin matrix and fibers. In this paper, the load-bearing capacity of FRP reinforced concrete after elevated temperature exposition are present. The results are compared with concrete sample with steel reinforcement. Commercially produced glass FRP (GFRP) and carbon FRP (CFRP) rebars with sand coatings surface treatments were implemented in concrete beam and subjected to four-point bending load. The residual flexural strength of reinforced concrete after heating to 1000°C was obtained and evaluated and compared to results of non-heated elements. The results indicate that fire resistance of FRP reinforced beams can reach at least 60 minutes according the standard ČSN EN 13501-2.
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