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The increased frequency and intensity of drought events are among the major impacts of climate change in various regions worldwide, including Central Europe. These changes have increased the demand for precise drought monitoring and forecasting tools and their validation. The Czech Drought Monitoring System, which is widely utilized across Central Europe, provides daily soil moisture monitoring and medium-range forecasts using the SoilClim model. The main objective of this study was to describe and evaluate the spatiotemporal reliability of these forecasts. The forecasting performance was evaluated for three variables (relative soil moisture content, soil moisture deficit, and drought intensity) and was evaluated using Pearson's correlation, mean bias error, and mean absolute error. All the statistical analyses were performed on data from the years 2019 to 2021 aggregated at the administrative district level in the Czech Republic. The growing season data were analyzed in detail to assess the forecasting accuracy during spring and summer. Furthermore, the ability to forecast rapid changes in the soil moisture content according to changes in meteorological variables, such as precipitation and air temperature, was evaluated. Our findings demonstrate that the SoilClim model forecasts are accurate and suitable for practical applications in sectors such as agriculture and forestry. The lowest reported correlation between the monitored and forecasted values was +0.68 for nine-day forecasts at a soil depth of 0–40 cm. For shorter forecast periods of one and four days, the correlation values were +0.80 or greater. For drought intensity, the errors did not exceed one category of drought severity. We identified summer as the most dynamic season, with corresponding variations in the soil moisture and meteorological forecasting accuracy. This study validates the ability of the Czech Drought Monitoring System to provide reliable soil moisture forecasts, thus contributing to our ability to manage and mitigate drought impacts effectively. • Local soil moisture forecasts were generally highly accurate. • Drought intensity forecast errors did not exceed one severity class. • Soil moisture forecasts were more accurate than meteorological variable forecasts. • The highest uncertainty in the soil moisture forecasts was observed during summer. • Rapid soil drying was reliably predicted from soil moisture forecasts. [ABSTRACT FROM AUTHOR]

Two micrometeorological methods utilizing high-frequency sampled air temperature were tested against eddy covariance (EC) sensible heat flux (H) measurements at three sites representing agricultural, agro-forestry, and forestry systems. The two methods cover conventional and newly proposed forms of the flux-variance (FV) and surface renewal (SR) schemes of differing complexities. The sites represent measurements in surface, roughness, and roughness to surface transitional layers. Regression analyzes against EC show that the most reliable FV and SR forms estimate H with slopes within ±10% from unity and coefficient of determination R 2 > 0. 9 across all the three sites. The best performance of both FV and SR was found at the agricultural site with measurements well within the surface layer, while the worst was found for the tall forest with measurements within the roughness sublayer where its thickness needed to be additionally estimated. The main variable driving H in FV is the temperature variance, whereas in SR, it is the geometry of ramp-like structures. Since these structures are also responsible for most of the temperature variance, a novel FV-SR approach emerging from combining the methods is proposed and evaluated against EC measurements and conventional FV and SR schemes. The proposed FV-SR approach requiring only a single fast response thermocouple is potentially independent of calibration and ameliorates some of the theoretical objections that arise when combining ramp statistics with similarity arguments. The combination of methods also provides new insights into the contribution of coherent structures to the temperature variance and its dependence on atmospheric stratification. Other potential utility of the new method is to include it in multi-tool assessments of surface energy fluxes, since a convergence or divergence of the results has a high diagnostic value. • High-frequency temperature measurements are used to predict sensible heat flux (H). • Predictions of H are made using flux-variance (FV) and surface renewal (SR) schemes. • FV and SR differ in assumptions about eddy sizes and their interaction with the surface. • Combining the FV and SR methods offers dual constraints on their stability dependence. • The proposed FV-SR method requires only fast response thermocouple and no calibration. [ABSTRACT FROM AUTHOR]

Poplars are among the most widely used short rotation woody coppice (SRWC) species but due to their assumed high water use, concerns have been raised with respect to large-scale exploitation and potentially detrimental effects on water resources. Here we present a quantitative analysis of the water requirements of poplar SRWC using experimental data and a soil water balance modelling approach at three different sites across Europe. We used (i) eddy covariance (EC) measurements (2004–2006) at an irrigated SRWC grown on a previous rice paddy in northern Italy, (ii) Bowen ratio and energy balance (BREB) measurements (2008–2015) and EC (2011–2015) at a SRWC in rain-fed uplands in the Czech Republic, and (iii) EC measurements (2010–2013) at a SRWC on a previous agricultural land with a shallow water table in Belgium. Without any calibration against water balance component measurements, simulations by the newly developed soil water balance model R-4ET were compared with evapotranspiration ( ET ) measurements by EC and BREB with a resulting mean root mean square error ( RMSE ) of 0.75 mm day −1 . In general, there was better agreement between EC and the model ( RMSE  = 0.66 mm day −1 ) when EC data were adjusted for lack of energy balance closure. A comparison of the simulated and measured soil water content yielded a mean RMSE of 0.03 m 3  m −3 . The mean annual crop coefficient, i.e. the ratio between actual and reference ET , was 0.82 (ranging from 0.65 to 0.95) while the monthly maxima reached 1.16. These values indicated that ET of poplar SRWC was significantly lower than ET of a well-watered grass cover at the annual time scale, but exceeded ET of the reference cover at shorter time scales during the growing season. We show that the model R-4ET is a simple, yet reliable tool for the assessment of water requirements of existing or planned SRWC. For very simple assessments on an annual basis, using a crop coefficient of 0.86 (adjusted to a sub-humid climate), representing an average value across the three sites in years with no evident drought stress, is supported by this analysis. [ABSTRACT FROM AUTHOR]

We examined the effect of throughfall exclusion on aboveground woody biomass (AGB) productivity in a short-rotation woody coppice plantation. This study was carried out between the 3 rd and 7 th year (2011–2015) of the second rotation cycle in hybrid poplar plantation ( Populus nigra  ×  P. maximowiczii ) in the Czech Republic. A partial-throughfall exclusion (R) treatment and a control (C) treatment were applied. Throughfall exclusion was set to 40% in 2011–2012 and increased to 70% thereafter. The annual mean (standard error) AGB productivity for C and R during 2012–2015 were 11.2 (0.84) and 10.1 (0.89) Mg ha −1 y −1 of dry matter (DM), respectively. The lowest AGB productivity and most pronounced reduction (18.8%) in the annual AGB productivity by the R treatment occurred in 2014 - a year with the driest spring. The observed inter-annual variability in AGB productivity was not explained by precipitation nor by precipitation-treatment interaction. However, the annual AGB productivity variation depended (p = 0.002) on the throughfall totals during period May–July. The total harvestable biomass in 2015 reached 81.9 (7.2) and 75.0 (6.2) Mg ha −1 DM for the C and R treatments, respectively. Despite the non-negligible mean treatment difference (5.7 Mg ha −1 DM, i.e. 7.6%), the large between-plot variance and shifts in stand structure resulted in the nonsignificant differences. We suggest that once the root system is established, hybrid poplar plantations are relatively resilient to drought and might act as an income-stabilizing factor when traditional agricultural crops fail to deliver viable yields in drier climate. [ABSTRACT FROM AUTHOR]

As bioenergy plantations are a relatively new phenomenon, long-term experimental data on their productivity and tolerance to environmental stress that provides a robust framework for site selection and potential productivity assessment is still lacking. To address this need, we developed a method to correlate the productivity of bioenergy plantations with local climate using tree-ring chronologies. Tree-ring width from 37 Populus nigra (age > 115 y) and 368 poplar hybrid ( Populus nigra × Populus maximowiczii ) (9–12 y) individuals were collected and analyzed at demonstration sites in the Czech Republic. The growth of mature, naturally grown solitary native trees and young congeneric hybrids grown in high density (∼10,000 ha −1 ) showed statistically significant correlations (r = 0.71, p < 0.05). Further, we found significant (p < 0.05) and consistent growth responses to changes in key seasonal climatic parameters (e.g., mean air temperature, number of dry days or cumulative heat sum (degree-days) during the growing season) for both natives and their hybrids. The analysis of climate conditions and the tree-ring records revealed a gradual change of climatic conditions since the 1930s, positively affecting poplar growth and indicated that longer rather than shorter harvest cycles are preferable to ensure stable yields at our experimental site. [ABSTRACT FROM AUTHOR]

We used the eddy-covariance technique to measure the temporal dynamics and the relationships between leaf area index (LAI) and exchanges of carbon dioxide (CO 2 ), latent heat (LE) and sensible heat (H) in a multi-genotype short-rotation poplar coppice (SRC) located in East-Flanders (Belgium). The study was carried out over four years (2010–2013) corresponding to the first two rotations of the plantation. The net carbon (C) balance during the first two-year rotation was 75.2 (±4.4) g C m −2 in the establishment year 2010 and −95.6 (±5.9) g C m −2 in 2011. After the harvest (second two-year rotation) the coppice was a net source of carbon, 151.0 (±10.5) g C m −2 in 2012, but a sink of −274.6 (±18.8) g C m −2 in 2013. Overall, at the end of the second rotation this SRC, was a net CO 2 sink with a cumulative uptake of −144.0 (±22.8) g C m −2 . The temporal dynamics and the magnitude of the ratio between gross primary production (GPP) and ecosystem respiration (R eco ) were similar to a deciduous forest. The evolution of LAI showed values ranging from 0.96 (±0.4) to 2.0 (±1.2) and from 5.1 (±1.5) to 4.5 (±0.84) during the first and the second rotation, respectively. The GPP (measured close to light saturation) was significantly related to LAI ( r 2 of 0.76, p < 0.001). The cumulative evapotranspiration (ET) measured during the first rotation was 241.7 mm and 349.9 mm for 2010 and 2011, respectively, and 464.6 mm and 372.1 mm for 2012 and 2013. The average value of surface conductance ( G s ) was 0.35 mol m −2 s −1 and 0.24 mol m −2 s −1 for the foliated and unfoliated periods, respectively. The mean decoupling factors (Ω) were 0.35 and 0.23 for the foliated and unfoliated periods, respectively, indicating that ET was primarily controlled by vapor pressure deficit (VPD) and G s (a well-coupled system). The mean Priestley–Taylor coefficient ( α ) was 0.77 and 0.53 for the foliated and the unfoliated periods, respectively. Such low values indicate that ET was significantly lower than the equilibrium evaporation and thus also lower than the ET of a hypothetical reference crop. During the whole experiment only two short episodes of drought were identified when in May–June 2011 and June 2013 the evaporative fraction dropped below 0.4. The analysis of G s showed a rather low stomatal control (anisohydric stomatal response) that put the poplar SRC at greater risk during severe drought conditions. All the three mentioned parameters related to ET and GPP ( G s , Ω and α ) were significantly and positively correlated to LAI ( r 2 from 0.14 to 0.2, p < 0.0001), suggesting that LAI was the main biophysical driver controlling the carbon and water balances in this bioenergy production system. [ABSTRACT FROM AUTHOR]

• Drought monitoring by voluntary reporters is a useful and reliable tool. • Reporters provide information about the moisture status and impacts of drought. • Data by reporters were highly correlated with models and drought indices. • Drought impact observations could detect the start of a drought earlier than model. Increasing drought is considered one of the major threats associated with climate change in central Europe. To provide an objective, quantitative tool that represents current drought conditions, the Czech Drought Monitor System (CzechDM) was established in 2012. Like other drought monitoring systems worldwide, the CzechDM uses several approaches to provide drought data. However, the CzechDM is unique internationally due to its utilization of a network of voluntary reporters (farmers) who complete a weekly online questionnaire to provide information about soil water content and the impacts of drought on crop yield. In this study, the results from the questionnaires from individual farms were aggregated by district. Reporters' data were compared and validated with the outputs of the SoilClim model (a core tool of the CzechDM) and with other drought monitoring tools, such as the water balance model, the soil water index and the evaporative stress index. The soil water content estimated by the reporters was significantly correlated (on average r = 0.8) with the outputs of the SoilClim model. Conversely, the correlation between the drought impacts on yield estimated by the reporters and the SoilClim outputs was lower (on average r = 0.4), suggesting that in situ observations by farmers provide additional insights into the occurrence of drought impacts. Importantly, it was found that farmers reported significant drought impacts on yield earlier in the season than any other methods (models or remote sensing). The main findings of this study are that the drought monitoring provided by reporters is a useful and reliable component of the CzechDM. We conclude that weekly reports by farmers represent a significant enhancement to drought monitoring and have potential for use in developing automated approaches that combine in situ , modeling and remote sensing data within a data fusion or machine learning framework. [ABSTRACT FROM AUTHOR]

Highlights: [•] ET of two short-rotation poplar coppices (SRCs) and two grass covers were compared. [•] The Bowen ratio/energy balance technique was applied for both types of vegetation. [•] Hourly, daily, and monthly ET was sometimes greater for SRCs. [•] ET over an entire annual cycle was always greater for grass vegetation. [•] SRC can replace grassland without a serious impact on the landscape ET. [ABSTRACT FROM AUTHOR]

Indicators based on evapotranspiration (ET) provide useful information about surface water status, response of vegetation to drought stress, and potential growth limitations. The capability of ET-based indicators, including actual ET and the evaporative stress index (ESI), to predict crop yields of spring barley and winter wheat was analyzed for 33 districts of the Czech Republic. In this study, the ET-based indicators were computed using two different approaches: (i) a prognostic model, SoilClim, which computes the water balance based on ground weather observations and information about soil and land cover; (ii) the diagnostic Atmosphere–Land Exchange Inverse (ALEXI) model based primarily on remotely sensed land surface temperature data. The capability of both sets of indicators to predict yields of spring barley and winter wheat was tested using artificial neural networks (ANNs) applied to the adjusting number and timeframe of inputs during the growing season. Yield predictions based on ANNs were computed for both crops for all districts together, as well as for individual districts. The root mean square error (RMSE) and coefficient of determination (R2) between observed and predicted yields varied with date within the growing season and with the number of ANN inputs used for yield prediction. The period with the highest predictive capability started from early-June to mid-June. This optimal period for yield prediction was identifiable already at the lower number of ANN inputs, nevertheless, the accuracy of the prediction improved as more inputs were included within ANNs.The RMSE values for individual districts varied between 0.4 and 0.7 t ha–1 while R2 reached values of 0.5–0.8 during the optimal period. Results of the study demonstrated that ET-based indicators can be used for yield prediction in real time during the growing season and therefore have great potential for decision making at regional and district levels. • Results of the study demonstrated that ET-based indicators can be used for yield prediction prior to harvest. • ET-based indicators can be employed as a useful tool for assessment of drought and its impact on agricultural crops. • ET-based indicators can be used in real time during the season and thus have great potential for decision making at regional and district levels. [ABSTRACT FROM AUTHOR]

• Decoupling and sub-canopy horizontal flow can bias forest NEE estimates. • The common u * filtering is not applicable at the study site. • Two new approaches for two-level filtering are introduced. • These two new approaches are applicable on short time scales. • Sonic anemometers above and below canopy are needed to reveal decoupling. Concurrent below and above canopy sonic anemometer vertical velocity (w) measurements reveal frequent decoupling events between the air masses below and above the canopy at a dense spruce forest stand in mountainous terrain. Decoupling events occurred predominantly during nighttime but not exclusively. Several single-level approaches based on steady state and integral turbulence characteristic tests as well as friction velocity (u *) filtering and two-level CO 2 flux filtering methods are tested. These tests aimed at evaluating the filtering schemes to address decoupling and its effect on above canopy derived eddy covariance net ecosystem CO 2 exchange (NEE). In addition to the already existing two-level filtering approach based on the correlation of σ w above and below canopy, two new filtering methods are introduced based on w raw data below and above the canopy. One is a telegraphic approximation agreement, which assumes coupling when w both above and below canopy are pointing in the same direction. Another one evaluates the cross-correlation maximum between below and above canopy w data. This study suggests that none of the single-level approaches can detect decoupling when compared to two-level filtering approaches. It further suggests that the newly introduced two-level approaches based on w raw data may have advantages in comparison to the conventional σ w approach regarding their flexibility on shorter time scales than one year. We tested the correlation of the newly introduced filtering approaches with the parameters u * , global radiation, buoyancy forcing across the canopy and wind shear across the canopy. In any case, this correlation was not existing or weakly positive, suggesting that concurrent below and above canopy measurements are necessary for addressing decoupling. Sonic anemometer measurements near the forest floor and above the canopy are adequate to apply the new procedures and can be implemented in a routine manner at any forest site globally. [ABSTRACT FROM AUTHOR]

We analyzed the effect of manipulated water availability on an accumulation of nutrients and metals, their stoichiometry, and allocation to roots or leaves in a short rotation coppice (SRC) poplar plantation. The aim of this study was also to clarify how these changes are related to the effects of drought on growth parameters. This study was conducted in Domanínek, Czech Republic in an SRC poplar clone J-105 ( Populus nigra L. ×  P . Maximowiczii H.). This plantation was established as an uncoppiced (single stem) and later on converted into multi-stem (coppice). A rain-out shelter experiment (reduced throughfall) was established in the second year of coppice and the drought stress (DS) applied for 3 years. Water availability altered the accumulation and allocation of nutrients and metals in above and belowground biomass. Reduced water availability led, in particular, to the significantly lower accumulation of potassium (K) in both leaves and roots and a higher carbon (C) to potassium (K) ratio (C:K) in leaves. The significant decline of zinc (Zn) was also found in roots under reduced throughfall. Reduced water availability led to increased accumulation of cadmium (Cd) in leaves and decreased accumulation in roots. This resulted in significantly lower root:leaf ratio for Cd content. An opposite response was found for the allocation of copper (Cu). We also demonstrated that major changes in accumulation and allocation are associated with changes in growth. The results indicated that such knowledge may contribute to understanding the role of nutrient uptake and translocation in acclimation to DS and it may help in developing phytoextraction methods on contaminated soils. [ABSTRACT FROM AUTHOR]

Accurate estimation of energy fluxes and evapotranspiration ( ET ) in agricultural systems is critically needed, especially for water resource sustainability, soil moisture monitoring and irrigation. Numerous micrometeorological methods have become commercially available. Considering the eventual trade-off between cost and accuracy, it is important to evaluate these methods to provide recommendations for practical purposes. Therefore, we tested five different techniques at one field in the region of Central Europe dominated by rainfed farming but suffers from drought spells. In an intensive campaign, we used eddy covariance (EC), large aperture and surface layer scintillometers, the Bowen ratio energy balance (BREB), and the surface renewal (SR) methods to estimate the sensible ( H) and latent ( λET ) heat fluxes of winter wheat and bare soil with harvest residues during two months in summer 2015. At the half-hourly level, the methods showed varying agreement under different field conditions. While H estimated by EC and scintillometry agreed well, there was an underestimation of λET by EC compared to the other methods, most likely due to energy balance non-closure. The λET estimated by the BREB method showed good agreement with the λET obtained by scintillometry when the Bowen ratio ( β ) was high and with the λET obtained by EC when β   →  0. Our study confirmed good reliability of scintillometers across wide range of meteorological conditions. Although the SR method provided the most inferior agreement with other methods at half-hourly basis, it was deemed to be valuable when longer averaging periods were used. Over the entire experiment, mean daily ET estimated by scintillometry (2.6 mm d −1 ), BREB (2.3 mm d −1 ), and SR (2.9 mm d −1 ) showed reasonable agreement while EC (1.6 mm d −1 ) significantly underestimated. This indicates that low cost methods (BREB and SR) are sufficient for water management purposes when a daily and longer time scales are important. Further, parallel deploying of BREB and SR can provide additional diagnostics and increase the confidence in ET estimates. [ABSTRACT FROM AUTHOR]

The close relationship between the onset and severity of agricultural and hydrological drought is considered self-evident, yet relatively few studies have addressed the effects of applying agricultural drought adaptation to hydrological drought characteristics. The present study applies a model cascade capable of simultaneously considering the interactions between agricultural and hydrological droughts. The study area covers all river basins in the Czech Republic and includes the periods of 1956–2015 (baseline) and 2021–2080 (future). The model cascade was shown to explain 91% of the variability in the seasonal and annual accumulated runoff and allows for the analysis of increasing/maintaining/decreasing available water capacity (AWC) across the 133 defined basins with a total area of c. 78,000 km2. The study reports that the probability and extent of agricultural drought increased over the entire period with higher AWC scenario showing slower pace of such increase especially from April to June. The trends in the extent or severity of hydrological droughts were of low magnitude. The future climate has been projected through the use of ensembles of five global (CMIP5) and five regional (EURO-CORDEX) climate models. The results showed a significant increase in the duration of agricultural drought stress and in the area affected throughout the year, particularly in July–September. The hydrological drought response showed a marked difference between areas with a negative and positive climatic water balance, i.e., areas where long-term reference evapotranspiration exceeds long-term precipitation (negative climatic water balance) and where it does not (positive climatic water balance). The overall results indicate that increasing soil AWC would decrease the frequency and likely also impact of future agricultural droughts, especially during spring. This result would be especially true if the wetter winters predicted by some of the models materialized. Hydrological droughts at the country level are estimated to become more pronounced with increasing AWC, particularly in catchments with a negative climatic water balance. • We analyzed the past and projected agricultural and hydrological droughts in 133 basins in the Czech Republic. • The area and severity of the agricultural drought during the growing season has increased since 1956. • The runoff and hydrological droughts have increased insignificantly since 1956 except for June. • The increase in the water holding capacity decreases area and severity of agricultural droughts but exacerbates hydrological ones. • Adaptation studies have to consider drought impacts simultaneously to avoid maladaptation. [ABSTRACT FROM AUTHOR]

Abstract: This study focuses on the changes in the yield stability of winter wheat and spring barley over the past 140 years and changes in the weather–yield relationships. The study area is located in the Czech Republic in eastern Central Europe between 48°37′–49°30′N and 15°29′–17°55′E and includes 4900km2 of arable land within eight districts for which yield data were collected for the years 1869–1913 and 1961–2007. The cropping systems in the region are dominated by rain-fed production of winter wheat, spring barley and winter rape. The yields for winter wheat and spring barley have increased by a factor of 2–3 since the late 19th century, whereas the temperature and precipitation patterns showed trends toward warmer and drier conditions. There was a considerable increase in the inter-annual variability of the absolute yields in the districts. When the variability was evaluated in relative terms (i.e., compared with the yield level), it showed no change or insignificant increases in the warmest and driest regions. The study also found that the sensitivity to inter-seasonal temperature increase was much more pronounced during 1961–2007 than at the end of the 19th century and that an increase of the mean temperature by 1°C led to yield decreases of up to 11% for winter wheat and up to 10% for spring barley. In contrast, the same temperature increase during the 1869–1913 period would have caused yield decreases of up to 8% and 5%, respectively. In the 1961–2007 period, the negative relationship between the temperature and yields of barley (wheat) was highly significant in seven (eight) of eight districts compared with only four (five) with a much weaker correlation in 1869–1913. During the early period, drier conditions had very small negative or even slightly positive effects on yields, whereas at the end of the 20th century, the May and June drought became a factor that explained a considerable proportion of the yield variability. This was the case especially for spring barley, which is more vulnerable to droughts than is winter wheat. The negative effects of increasing temperature and drought on grain yield were most pronounced in the districts that are currently the warmest and driest. The increasing vulnerability of wheat and barley production to increasing temperatures and droughts over time should be addressed by plant breeders, as there are relatively few adaptation options available to farmers except switching to other crops, which cannot fully substitute for wheat and barley. [Copyright &y& Elsevier]

Abstract: The newly developed SoilClim model is introduced as a tool for estimates of reference (ETo) and actual (ETa) evapotranspiration, presence of snow cover, soil temperature at 0.5m depth and the soil moisture course within two defined layers. It enables one to determine the soil moisture and temperature regimes according to the United States Department of Agriculture (USDA) soil taxonomy. SoilClim works with daily time steps and requires maximum and minimum air temperature, global solar radiation, precipitation, vapor pressure and wind speed as meteorological inputs as well as basic information about the soil properties and vegetation cover. The behavior of SoilClim was assessed using observations at 5 stations in central Europe and 15 stations in the central U.S. The modeled ETo was compared with atmometers so that the coefficient of determination (R 2) was 0.91 and root mean square error (RMSE) was 0.53mm. The estimated ETa was compared against eddy-covariance and Bowen ratio measurements (R 2 varied from 0.74 to 0.80; RMSE varied from 0.49 to 0.58mm). The soil temperature (at 0.5m depth) was estimated with good accuracy (R 2 varied from 0.94 to 0.97; RMSE varied from 1.23°C to 2.95°C). The ability of the SoilClim model to mimic the observed soil water dynamics was carefully investigated (relative root mean square error rRMSE varied from 2.8% to 34.0%). The analysis conducted showed that SoilClim gives reasonable estimates of evaluated parameters at a majority of the included stations. Finally, a spatial analysis of soil moisture and temperature regimes (according to USDA) within the region of the Czech Republic and the northern part of Austria under present conditions was conducted and diagnosed the appearance of Perudic, Subhumid Udic, Dry Tempudic (the highest frequency), Wet Tempustic and Typic Tempustic. The simulated mean soil temperature (0.5m depth) varied from less than 7.0°C to 11.0°C throughout this region. Based on these results, the SoilClim model is a useful and suitable tool for water balance and soil climate assessment on local and regional scales. [Copyright &y& Elsevier]

• Fuel aridity and high-risk fire weather have increased substantially since 1956 • The trends are more severe during April-June and linked to the climate change • Fuel aridity levels explain 70% of interannual variability in number of wildfires • Marked increase in wildfire-conducive conditions is expected by 2050 • Forested areas above 500 m asl. are expected to see largest increases The occurrence of major wildfires in countries such as Portugal, Italy and Spain (2017) and Sweden (2018) indicated that wildfires pose a risk across Europe. While Central Europe has not been at the center of such events, observed climate data and climate projections suggest a tendency toward more years with wet and warm winters and dry and hot summers as well as fuel accumulation, leading to more hazardous conditions. Although some existing studies analyzed the differences in wildfire occurrence in this territory based on terrain, soil or vegetation characteristics, the effects of climate change have not been properly appraised. To fill this knowledge gap, we used and tested an ensemble of nine fuel aridity metrics, including three dedicated fire danger rating indices, and evaluated their level of agreement with actual fire occurrence, their ability to explain the interannual variability in wildfire frequency, and their temporal trends. The analysis covered the entire territory of the Czech Republic at 500 m spatial resolution. Two periods were included based on observed (1956–2015) and projected (2020–2100) meteorological data using ensembles of five regional climate models (RCMs) and five global circulation models (GCMs) based on Euro-CORDEX and CMIP5 datasets. For the future, we considered Representative Concentration Pathway (RCP) 4.5. Our results showed that since 1956, most of the Czech territory has exhibited an increasing frequency of fire weather days (i.e., days with highly conducive wildfire conditions) and an increasing area affected by weather conducive to wildfire occurrence, with the trends accelerating after 2000. The annual variation in the fuel aridity levels (derived solely from meteorological data) explained more than 2/3 of the reported wildfire variability during 1991–2015 over the Czech Republic. The future projections based on the RCM or GCM ensembles indicated a significant increase in fuel aridity and an increase in the area under fire-conducive conditions. Recommendations derived from such robust results are provided for stakeholders seeking to implement adaptation measures. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hummocks had higher potential CO 2 and CH 4 production than hollows or subsurface peat. • Temperature increased potential CO 2 and CH 4 production and enzyme activities. • CH 4 production occurred primarily under saturated conditions. • Acetoclastic methanogenesis likely dominant CH 4 producing pathway. Coastal wetlands store significant amounts of carbon (C) belowground, which may be altered through effects of rising temperature and changing hydrology on CO 2 and CH 4 fluxes and related microbial activities. Wetland microtopography (hummock-hollow) also plays a critical role in mediating plant growth, microbial activity, and thus cycling of C and nutrients and may interact with rising seas to influence coastal wetland C dynamics. Recent evidence suggests that CH 4 production in oxygenated surface soils of freshwater wetlands may contribute substantially to global CH 4 production, but comprehensive studies linking potential CH 4 production to environmental and microbial variables in temperate freshwater forested wetlands are lacking. This study investigated effects of temperature, moisture, and microtopography on potential net CO 2 and CH 4 production and extracellular enzyme activity (β-glucosidase, xylosidase, phenol oxidase, and peroxidase) in peat soils collected from a freshwater forested wetland in coastal North Carolina, USA. Soils were retrieved from three microsites (hummock, hollow, and subsurface peat soils (approximately 20–40 cm below surface)) and incubated at two temperatures (27 °C and 32 °C) and soil water contents (65% and 100% water holding capacity (WHC)). Hummocks had the highest cumulative potential net CO 2 (13.7 ± 0.90 mg CO 2 -C g soil−1) and CH 4 (1.8 ± 0.42 mg CH 4 -C g soil−1) production and enzyme activity, followed by hollows (8.7 ± 0.91 mg CO 2 -C g soil−1 and 0.5 ± 0.12 mg CH 4 -C g soil−1) and then subsurface soils (5.7 ± 0.70 mg CO 2 -C g soil−1 and 0.04 ± 0.019 mg CH 4 -C g soil−1). Fully saturated soils had lower potential net CO 2 production (50–80%) and substantially higher potential net CH 4 production compared to non-saturated soils (those incubated at 65% WHC). Soils incubated at 32 °C increased potential net CO 2 (24–34%) and CH 4 (56–404%) production under both soil moisture levels compared to those incubated at 27 °C. The Q 10 values for potential net CO 2 and CH 4 production ranged from 1.5 to 2.3 and 3.3–8.8, respectively, and did not differ between any microsites or soil water content. Enrichment of δ13CO 2 -C was found in saturated soils from all microsites (−24.4 to − 29.7 ‰) compared to non-saturated soils (−31.1 to − 32.4 ‰), while δ13CH 4 -C ranged from −62 to −55‰ in saturated soils. Together, the CO 2 and CH 4 δ13C data suggest that acetoclastic methanogenesis is an important pathway for CH 4 production in these wetlands. A positive relationship (Adj. R2 = 0.40) between peroxidase activity and CH 4 production was also found, indicating that peroxidase activity may be important in providing fermented C substrates to acetoclastic methanogenic communities and contribute to anaerobic C mineralization. These results suggest that changes in temperature and hydrology could stimulate CO 2 and CH 4 emissions from surface hummock soils, and to a lesser extent from hollow soils, and provide preliminary evidence that hummocks may be a spatially important and unrecognized hotspot for CH 4 production. [ABSTRACT FROM AUTHOR]