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The forests of central Europe have undergone remarkable transitions in the past 40 years as air quality has improved dramatically. Retrospective analysis of Norway spruce (Picea abies) tree rings in the Czech Republic shows that air pollution (e.g. SO2 concentrations, high acidic deposition to the forest canopy) plays a dominant role in driving forest health. Extensive soil acidification occurred in the highly polluted "Black Triangle" in Central Europe, and upper mineral soils are still acidified. In contrast, acidic atmospheric deposition declined by 80% and atmospheric SO2 concentration by 90% between the late 1980s and 2010s. In this study we oserved that annual tree ring width (TRW) declined in the 1970s and subsequently recovered in the 1990s, tracking SO2 concentrations closely. Furthermore, recovery of TRW was similar in unlimed and limed stands. Despite large increases in soil base saturation, as well as soil pH, as a result of repeated liming starting in 1981, TRW growth was similar in limed and unlimed plots. TRW recovery was interrupted in 1996 when highly acidic rime (originating from more pronounced decline of alkaline dust than SO2 from local power plants) injured the spruce canopy, but recovered soon to the pre-episode growth. Across the long-term site history, changes in soil chemistry (pH, base saturation, Bc/Al soil solution ratio) cannot explain observed changes in TRW at the two study sites where we tracked soil chemistry. Instead, statistically significant recovery in TRW is linked to the trajectory of annual SO2 concentrations or sulfur deposition at all three stands. [ABSTRACT FROM AUTHOR]

This study focuses on estimation of the impacts of anticipated global climate change on water balance in forested headwater catchment. The investigated catchment is located in the Šumava National Park (Bohemian Forest) in the southern part of the Czech Republic. We calculated nine future water balance scenarios for periods of 2021-2050 and 2071-2100. We used data from following models: CNRM-CM5_ALADIN53, EC-EARTH_RACMO22E, EC-EARTH_RCA4, and MPI-ESM-LR_CCLM4-8-17 with 3 emission scenarios (Representative Concentration Pathways RCP2.6, 4.5, 8.5). Corrected regional climate model daily data were used in combination with hydrological model Brook90. The scenarios projected an increase of mean annual temperature of 1.1°C (RCP4.5) and 1.4°C (RCP8.5, 2021-2050) and 2.3°C (RCP4.5) and 4.2°C (RCP8.5, 2071-2100) and increase in mean annual precipitation amount of 11% (RCP 4.5) and 15% (RCP 8.5, 2021-2050) and 15% (RCP 4.5) and 20% (RCP8.5, 2071-2100). It would result in a mean annual runoff increase of 9% (RCP4.5) and 14% (RCP8.5, 2021-2050) and 12% (RCP4.5) and 16% (RCP8.5, 2071-2100). The annual runoff cycle is projected to change significantly especially in the period of 2071-2100, when a large winter runoff increase and a spring runoff maximum decrease is expected. "Pessimistic" RCP8.5 scenarios expect even no spring runoff maxima from snowmelt and project a shift of runoff maxima to December. [ABSTRACT FROM AUTHOR]

Streamwater chemistry in the Šumava National Park (Czech part of the Bohemian Forest) was observed in three periods: 1984-1990, 2003-2004, and 2010. Declining acidic deposition of S and N followed by decline of sulphate and nitrate concentration was driving force for recovery from acidification until years 2003-2004. Later, forest disturbance have led to changes in soil chemistry and have altered N soil availability resulting in enhanced nitrogen leaching from soil to surface waters between 2003-2004 and 2010. [ABSTRACT FROM AUTHOR]

The aims of the present study were (i) to evaluate trends in runoff from small forested catchments of the GEOMON (GEOchemical MONitoring) network during the period 1994-2011, and (ii) to estimate the impact of anticipated climate change projected by ALADIN-Climate/CZ regional climate model coupled to ARPEGE-Climate global circulation model and forced with IPCC SRES A1B emission scenario on flow patterns in the periods 2021-2050 and 2071-2100. There were no general patterns found indicating either significant increases or decreases in runoff on either seasonal or annual levels across the investigated catchments within 1994-2011. Annual runoff is projected to decrease by 15% (2021-2050) and 35% (2071-2100) with a significant decrease in summer months and a slight increase in winter months as a result of expected climate change as simulated by the selected climate model. [ABSTRACT FROM AUTHOR]

Abstract: Hydrochemical patterns resulting from differing bedrock geochemistry were ascertained by concurrent streamwater sampling in three small catchments, each underlain by geochemically contrasting silicate rock types in the western Czech Republic, Central Europe in 2001–2010. The catchments are situated 5–7km apart in the Slavkov Forest and are occupied by Norway spruce (Picea abies) plantations. They have similar altitude, area, topography, mean annual air temperature, and atmospheric deposition fluxes. The amount of base cations oxides (Ca+Mg+Na+K) is markedly different among the three studied rocks (leucogranite 8%, amphibolite 22%, serpentinite 36%). The leucogranite contains a very small amount of MgO, while the serpentinite contains extremely large amounts of MgO. The amphibolite contains an intermediate amount of MgO and elevated CaO. The Lysina, on leucogranite, exhibited very small concentrations of Mg (median 0.4mgL−1) in streamwater; Pluhův Bor, on serpentinite, contained extremely high concentrations of streamwater Mg (18mgL−1). Streamwater in the Na Zeleném catchment, on amphibolite, contained an intermediate amount of Mg and an elevated Ca. Very low pH (4.2), negative alkalinity (−60μeqL−1) and high inorganic monomeric Al concentrations (0.3mgL−1) were found in the stream draining leucogranite. Serpentinite streamwater exhibited the highest pH (7.6), alkalinity (+940μeqL−1) and Ni concentrations (100μgL−1). Aquatic chemistry reflected the composition of the underlying rocks within the studied catchments. Contrasting streamwater compositions of the studied catchments were generated according to the MAGIC model simulations mainly by differences in chemical weathering rates of base cations (65meqm−2 a−1 at Lysina, 198meqm−2 a−1 at Na Zeleném, and 241meqm−2 a−1 at Pluhův Bor). [Copyright &y& Elsevier]

Climate change is predicted to lead to an increase in extreme rainfall and, in coastal areas, sea-salt deposition events. The impacts of these two climatic extremes on stream hydrochemistry were separately evaluated via a novel watering manipulation at the Gårdsjön experimental catchment, SW Sweden. In summer 2004, a 2000 m hillslope draining to a defined stream reach was brought to a high-flow hydrological steady state for a 9 day period by sustained addition of 'clean' water using a distributed sprinkler system. Marine ions were then added, to generate a realistic 'sea salt' episode. A remarkably well constrained hydrological response was observed, such that a simple two-compartment mixing model could reasonably well reproduce observed conservative tracer (chloride, Cl) measurements, and 78% of added water was recovered in runoff. Stream base cation concentrations and acidity responded predictably to clean water and sea-salt addition, with the former leading to an increase in pH and acid neutralising capacity, and the latter to episodic acidification through hydrogen ion and aluminium displacement from soil exchange sites by marine base cations. Anion responses were less predictable: water addition caused a flush of nitrate, but this was apparently independent of rainfall composition. Sulphate remained near-constant during clean water addition but declined sharply during sea-salt addition, indicative of a strong, pH-dependent solubility control on leaching, presumably adsorption/desorption in the mineral soil. Most strikingly, dissolved organic carbon (DOC) concentrations were stable during clean water addition but varied dramatically in response to sea-salt addition, exhibiting a strong negative correlation with Cl concentrations in water draining the organic soil. These observations provide a robust experimental verification of the hypothesis that deposition chemistry, through its influence on acidity and/or ionic strength, has a major influence on DOC leaching to surface waters. [ABSTRACT FROM AUTHOR]

Abstract: Aluminum (Al) chemistry was studied in soils and waters of two catchments covered by spruce (Picea abies) monocultures in the Czech Republic that represent geochemical end-members of terrestrial and aquatic sensitivity to acidic deposition. The acid-sensitive Lysina catchment, underlain by granite, was compared to the acid-resistant Pluhův Bor catchment on serpentine. Organically-bound Al was the largest pool of reactive soil Al at both sites. Very high median total Al (Alt) concentrations (40μmolL−1) and inorganic monomeric Al (Ali) concentrations (27μmolL−1) were observed in acidic (pH 4.0) stream water at Lysina in the 1990s and these concentrations decreased to 32μmolL−1 (Alt) and 13μmolL−1 (Ali) in the 2000s. The potentially toxic Ali fraction decreased in response to long-term decreases in acidic deposition, but Ali remained the largest fraction. However, the organic monomeric (Alo) and particulate (Alp) fractions increased in the 2000s at Lysina. In contrast to Lysina, marked increases of Alt concentrations in circum-neutral waters at Pluhův Bor were observed in the 2000s in comparison with the 1990s. These increases were entirely due to the Alp fraction, which increased more than 3-fold in stream water and up to 8-fold in soil water in the A horizon. Increase of Alp coincided with dissolved organic carbon (DOC) increases. Acidification recovery may have increased the content of colloidal Al though the coagulation of monomeric Al. [Copyright &y& Elsevier]

Temporal trends in DOC concentration and flux were investigated at two geochemically distinct forested catchments in western Czech Republic. Mean discharge-weighted DOC concentrations averaged 18.8 mg L-1 at the acidic Lysina catchment, and 20.2 mg L-1 at base-rich and well-buffered Pluhuv Bor. Between 1993 and 2007 DOC in streamwater increased significantly in both catchments: the mean annual increase was 0.42 mg L-1yr-1 (p < 0.001) at Lysina and 0.43 mg L-1yr-1 (p <0.001) at Pluhuv Bor, resulting in cumulative increases of 64 and 65%, respectively. These long-term increases in streamwater DOC were correlated with only modest increases in stream pH in both catchments, but large declines in ionic strength (IS), that resulted from declining atmospheric deposition. Neither catchment has undergone changes in soil-water pH, yet DOC concentrations tripled in the soil-water of both catchments. We conclude that changes in ionic strength of soil-water and streamwater, rather than acidity, are the primary drivers of changes in streamwater DOC in this region. Temperature, precipitation and discharge show no statistically significant trends during the study period, suggesting that climate change has played no role in the changes in DOC that we have observed. [ABSTRACT FROM AUTHOR]

Abstract: The effect of European beech (Fagus sylvatica) and Norway spruce (Picea abies) on acid deposition and soil water chemistry was studied at a site in the Ore Mts., Czech Republic, that has been subjected to decades of elevated acidic deposition. Dry deposition onto the spruce canopy significantly increased acid input to the soil in comparison to the beech canopy. As a result soil waters were more acidic; Al, , and concentrations were significantly higher; and Ca and K concentrations were lower in the spruce stand than in the beech stand. The concentrations of potentially toxic inorganic aluminium (Alin) were, on average, three times higher in the spruce stand than in the beech stand. Thus, Al played a major role in neutralizing acid inputs to mineral soils in the spruce stand. Despite the higher dissolved organic carbon (DOC) concentrations in spruce organic soil solutions, organic Al (Alorg) accounted for only 30% of total Al (Altot), whereas in beech organic soil solutions Alorg was 60% of Altot. Soil waters in the beech stand exhibited Alin concentrations close to solubility with jurbanite (Al(SO4)OH·5H2O). The more acidic soil waters in the spruce stand were oversaturated with respect to jurbanite. The Bc/Alin ratio (Bc=Ca+Mg+K) in O horizon leachate was 4.6 and 70 in spruce and beech stands, respectively. In beech mineral soil solutions, the Bc/Alin ratio declined significantly to about 2. In the spruce stand, mineral soil solutions had Bc/Alin values below the critical value of 1. The observed Bc/Alin value of 0.4 at 30cm depth in the spruce stand suggests significant stress for spruce rooting systems. A more favourable value of 31 was observed for the same depth in the beech stand. The efficiency of the spruce canopy in capturing acidic aerosols, particulates, and cloud water has resulted in the long-term degradation of underlying soils as a medium for sustainable forest growth. [Copyright &y& Elsevier]

The acid/base properties of dissolved organic carbon (DOC) are an important feature of soil and surface waters. Large differences in the acid/base properties of DOC found by different studies might be interpreted as spatial and temporal differences in these properties. Different analytical techniques, however, may explain some of the differences. We used a combination of ion-exchange techniques, titration, and surface water chemistry data to evaluate DOC character from two substantially different areas—the relatively pristine boreal zone of Sweden and the heavily acidified temperate zone of the Czech Republic. We found a significantly higher site density (amount of carboxylic groups per milligram of DOC) for the Swedish sites (10.2 µequiv/mg of DOC ± 0.6) as compared to the Czech sites (8.8 µequiv/mg of DOC &plusm; 0.5). This suggests a slightly higher buffering capacity for Swedish DOC. A triprotic model of a type commonly incorporated in biogeochemical models was used for estimating the DOC dissociation properties. For Swedish sites, the following constants were calibrated: pK[sub a1] = 3.04, pK[sub a2] = 4.51, and pK[sub a3] =- 6.46, while the constants for Czech sites were pK[sub a1] = 2.5, pK[sub a2] = 4.42, and pK[sub a3] = 6.7. Despite differences in site density values, both models predict very similar dissociation and thus pH buffering by DOC in the environmentally important pH range of 3.5-5.0. This can be incorporated into models to make reliable estimates of the effect of organic acids on pH and buffering in different regions. [ABSTRACT FROM AUTHOR]

The role of organic acids in buffering pH in surface waters has been studied using a small brownwater stream (26 mg L−1 TOC) draining a forested catchment in Northern Sweden. Under the conditions of elevated pressure of CO2 stream field pH was changed between 3.5 and 6.1 during the acidification and alkalinization experiment. Acid–base characteristics of the natural organic matter were also determined using a high precision potentiometric method for a concentrated sample from the same stream. We compared the predictions from the Windermere Humic Aqueous Model (WHAM Model V), a model derived from the potentiometric titration (diprotic/monoprotic acid model) and a previously derived triprotic acid model which only uses alkalinity and TOC as input variables. The predicted buffering characteristics of all three models are very similar in the pH range 4.5–7 which suggests that during routine analysis alkalinity and TOC are sufficient to give a good estimate of organic acid anion charge contribution in a large range of surface waters. A slightly adjusted version of WHAM V successfully describes the organic charge contribution in a large number of sampled surface water lakes, which were previously used to calibrate the triprotic model. [Copyright &y& Elsevier]

The article discuses the electrolyte solubility theory for determining the riverine dissolved organic carbon (DOC) flux. It is reported that the organic substances contributing to DOC in surface waters has various origins and range widely in molecular size and chemical characteristics. It is further reported that electrolyte solubility theory explains how declining precipitation ionic strength (IS) has increased the dissolution of thermally moderated pools of soluble soil organic matter (OM).

Similar to other analytical techniques, the performance of laser-induced breakdown spectroscopy (LIBS) is significantly influenced by the selection of optimal experimental parameters. The optimization of LIBS is challenging because the laser–matter interaction and subsequent plasma formation are influenced not only by selected experimental parameters but also by the physical and mechanical properties of the sample. The goal of this work is to develop an artificial neural network (ANN) that is able to predict the signal-to-noise ratio (SNR) of selected spectral lines based on specific experimental parameters (laser pulse energy and gate delay) and on the sample's physical and mechanical properties. The ANN training was based on input data obtained from a high number of measurements of three certified materials with highly different mechanical and physical properties (low alloyed steel, glass, and aluminium alloy) with 2079 combinations of experimental parameters – gate delay (GD) and laser pulse energy (E). The ANN was optimized in terms of the number of neurons and hidden layers. The minimal number of input data points was studied with emphasis on the ANN prediction accuracy expressed as the determination coefficient R2 (predicted vs. measured values). The number of input data points was studied from three points of view – a minimal number of experimental parameters for one matrix, a minimal amount of data from different matrices, and a minimal number of different spectral lines. It has been shown that at least 20 different combinations of experimental parameters are necessary for one matrix to obtain reasonable performance of the ANN. However, only ten combinations are needed when a new matrix is added to the working model. It has also been shown that the prediction accuracy is poor for spectral lines which were not part of the training data. Finally, the ANN was utilized to predict the SNR of selected spectral lines in a specific range of experimental parameters. The parameters with the maximal SNR were studied, and the values were discussed with an emphasis on sample properties. It has been concluded that the optimization process can be substituted or significantly shortened by means of the ANN. [ABSTRACT FROM AUTHOR]

Changes in atmospheric deposition, stream water chemistry, and solute fluxes were assessed across 15 small forested catchments. Dramatic changes in atmospheric deposition have occurred over the last three decades, including a 70% reduction in sulphur (S) deposition. These changes in atmospheric inputs have been associated with expected changes in levels of acidity, sulphate and base cations in streams. Soil retention of S appeared to partially explain rates of chemical recovery. In addition to these changes in acid-base chemistry we also observed unexpected changes in nitrogen (N) biogeochemistry and nutrient stoichiometry of stream water, including decreased stream N concentrations. Among all catchments the average flux of dissolved inorganic nitrogen (DIN) was best predicted by average runoff, soil chemistry (forest floor C/N) and levels of acid deposition (both S and N). The rate of change in stream DIN flux, however, was much more closely correlated with reductions in rates of S deposition rather than those of DIN. Unlike DIN fluxes, the average concentrations as well as the rates of decline in streamwater nitrate (NO) concentration over time were tightly linked to stream dissolved organic carbon/dissolved organic nitrogen ratios DOC/DON and DON/TP rather than catchment characteristics. Declines in phosphorus adsorption with increasing soil pH appear to contribute to the relationship between C, N, and P in our study catchments. Our observations suggest that catchment P availability and its alteration due to environmental changes (e.g. acidification) might have profound effects on N cycling and catchment N retention that have been largely unrecognized. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to estimate future water balance and streamwater chemistry changes, according to different climate change scenario, in a forested acid-sensitive catchment. The investigated Czech catchment was affected by large anthropogenic acidification in the 20th century. Runoff for the year 2070 and streamwater chemistry for the period 1860–2070 were simulated by the models Brook90 and MAGIC, respectively. The runoff would change from 450mma−1 (1990–2006) to 320–402mma−1 for the year 2070 according to Brook90 simulations with bias-corrected regional climate model (RCAO) data with A2 emission scenario. Future streamwater concentration would maintain at the current level of approximately 90μeqL−1 (2008–2009) in the case of minimum or no change in runoff, or would increase by 10–30% as a result of projected runoff decrease. The runoff change would increase the concentration of base cations of a similar magnitude compared to the measured 160μeq L−1 (2008–2009). According to both scenarios, the effect of climate change on pH would be small and would lead to slight re-acidification of streamwater compared to the measured 4.2 (2008–2009). The climate change influence to streamwater chemistry would be small compared to the influence of atmospheric acid deposition. The environmental condition of the stream will probably remain unsatisfactory until the 2070s. [Copyright &y& Elsevier]

In this study, we present a map of the geochemical reactivity of rocks of the Czech Republic at a scale of 1:1,000,000 based on a geodatabase of regional geological maps at a scale of 1:50,000, as well as description of the method of how the map was developed. Research for this study was performed by compiling information between a database of regional geological maps and data from the lithogeochemical database to calculate and classify the rocks into eight groups according to carbonate content and coefficient of alkalinity. Rocks in these groups were further subdivided according to the susceptibility to weathering, forming a total of 28 categories. Knowledge of geochemical background is essential for making informed landscape management decisions, as this information determines the areas with higher levels of susceptibility to soil acidification and/or nutrient degradation. The map from this study will therefore provide essential information, albeit incomplete, to aid landscape management practitioners. [ABSTRACT FROM AUTHOR]

The MAGIC model was applied to estimate soil and soil water (−90cm) chemistry between 1854 and 2094 at two experimental stands (Načetín, Ore Mountains), one covered by a Norway spruce monoculture and the other by a natural European beech forest. The primary aims were to evaluate the influence of tree species on long-term acidification and to predict future development under different forest management scenarios. Depletion of base cations from the soils, caused by high acidic deposition, resulted in low base saturations of 8.2% at the spruce stand and of 6.4% at the beech stand in 2003. The concentration of aluminum in soil water was 135μmoll−1 and pH 4.32 at the spruce stand, and 70μmoll−1 and pH 4.4 at the beech stand, respectively, in 2005. During the peak of acidification in the mid 1980s, modeled aluminum concentrations contributed 70% to neutralizing acidity at the spruce stand, and 55% at the beech stand. In addition, SO4 concentration was significantly higher at the spruce stand (525μequiv.l−1) compared to the beech stand (330μequiv.l−1) as a result of higher dry deposition onto the spruce canopy. The enhanced leaching of base cations was comparable at both stands (191μequiv.l−1 at the spruce stand and 215μequiv.l−1 at the beech stand). The higher deposition of base cations onto the spruce canopy was able to partially mitigate the effect of high leaching. The model results suggest that future recovery of soil water will be significantly better at the beech stand (higher pH, ANC, Bc/Al ratio and lower SO4 2− and Al concentrations). Interestingly, modeled soil base saturation for 2094 will be lower at the beech stand. Alternative scenarios such as clear-cutting and new re-forestation resulted in more favorable soil chemistry for the beech plantations compared to the spruce. The best regeneration of the soil environment is predicted for the scenario with an absence of forest. This suggests, that future soil recovery from acidification will be delayed by the removal of base cations through harvesting. [Copyright &y& Elsevier]

Temperate forest ecosystems store most of the organic carbon in soils (SOC), and changes in the soil carbon stock due to climate change or land management can potentially have a large influence on carbon balance. The most important factors controlling the SOC pool on a global scale are generally agreed upon; however, estimations of SOC pools differ significantly among studies at regional and local scales due to different sampling protocols and local scale variability. This study evaluates the SOC pool in the forest floor and mineral soil sampled down to a depth of 80 cm in 14 forested catchments with variable environmental conditions and soil acidification and eutrophication legacies, and determines the best explanatory variables of the SOC pool. The average SOC pool of 34 t ha−1 measured in the forest floor (O horizon) was best explained by measures of historical sulphur (S) deposition (i.e., soil acidification legacy) and forest type (conifer vs. broadleaf forest). An average total SOC pool of 132 t ha−1, combining both the carbon pool in the mineral soil down to 80 cm and the carbon pool in forest floor, was best explained solely by elevation, which reflects temperature and precipitation gradients. However, when considering the coupled SOC pool in the forest floor and upper half of the sampled mineral soil (down to 40 cm), natural environmental factors were outweighed by anthropogenic ones (soil acidification legacy and forest type). This has important implications for understanding potential SOC pool changes under ongoing global climate change, especially in regions currently or historically affected by soil acidification caused by acid deposition. The acidification effect on the SOC accumulation and subsequent soil recovery after acidification retreat might affect carbon balance. Highlights: The SOC pool is dependent on soil acidification legacy, forest type and climatic gradient.Anthropogenic factors outweigh the natural ones if shallow sampling is carried out.Shallow sampling commonly carried out in forest soils underestimates the SOC pool.Soil acidification caused SOC accumulation and subsequent soil recovery might lead to carbon loss. [ABSTRACT FROM AUTHOR]

Recently, data statements have been required in hydrological manuscripts. Authors are usually confused by different data management policies. Thus, a frequent response is to write down "data available upon request from the corresponding author". Such a simplified response may lead to dormancy or permanent loss of data. We present an example of data management from a published hydrological modelling study. We started from figures with complete scientific stories in the publication and traced backwards to find relevant source data through workflows (linking). In this manner, the source data can be identified (archiving) and preserved (hosting). Such simple practices of data linking, archiving and hosting can rescue data and require only limited effort by the authors. We suggest that this data rescue process(es) should become routine in the scientific publication process. The data rescued with workflows can significantly improve the research transparency and reusability, which leads to a fairer and more open culture in hydrology. [ABSTRACT FROM AUTHOR]

• Higher runoff of Mg, Ca and Sr than atmospheric input suggests geogenic origin. • Over 90% of geogenic Mg is supplied by biotite, most Ca and Sr comes from plagioclase. • δ26Mg, δ44Ca and 87Sr/86Sr ratios of these main source minerals dominate also runoff. • Whole rock is not a good proxy for Mg, Ca and Sr isotopes released to the ecosystem. • Analysis of 1–2 minerals suffices to represent bedrock in runoff origin studies. Knowledge of the origin of magnesium (Mg) and calcium (Ca) in soil solutions and catchment runoff helps to predict forest ecosystems' vulnerability to deficiencies in essential nutrients in an era of climate change, environmental pollution and bark-beetle calamities. Here we discuss isotope aspects of Mg, Ca and strontium (Sr) cycling in a spruce-forested headwater catchment in a relatively unpolluted part of Central Europe. We investigated to what extent Mg and Ca isotope signatures of runoff reflect the isotope compositions of specific Mg- and Ca-rich minerals that easily dissolve during the weathering of paragneiss, and compared the isotope variability of Mg and Ca in fresh bedrock minerals, soils and other ecosystem reservoirs. We also compared conclusions from Mg and Ca isotope systematics with inferences from catchment input–output mass budgets. Long-term input–output monitoring in the studied catchment situated near the Czech–German border (Central Europe) revealed 3.5–7 times higher outputs of Mg, Ca, and Sr via surface runoff relative to their present-day atmospheric inputs. It follows that hydrological exports of recent atmospheric Mg, Ca and Sr are minor. Release of geogenic base cations into the runoff results from the interplay between mineral abundances, concentrations of the studied elements in the minerals, and their dissolution rates. Chemical depletion fractions for the studied elements from bedrock to the soil were 50–70 %, and the losses of dominant soluble minerals in the soil were 30–80 %. Exports of residual Mg, Ca and Sr following partial incorporation of these elements into secondary phyllosilicates are probably low because newly-formed clay minerals are not abundant in the soil. Residual Ca following preferential incorporation of isotopically light Ca into growing tree biomass may contribute to the isotopically heavy runoff Ca. Isotope ratios of base cations were obtained for six minerals (plagioclase, orthoclase, biotite, muscovite, apatite, and ilmenite). Mineral fractions differ greatly in δ26Mg and δ44Ca values and 87Sr/86Sr ratios. 80–97 % of each of the three studied base cations are present in the bedrock in a single relatively easily dissolvable mineral: Mg in biotite, and Ca and Sr in plagioclase. The isotope composition of Mg in biotite was similar to the isotope composition of Mg in runoff. The isotope compositions of Ca and Sr in plagioclase were also similar to Ca and Sr isotope compositions in runoff. Thus, the dominant geogenic source of each of the studied elements (Mg, Ca and Sr) in the investigated paragneiss catchment can be represented by one relatively soluble mineral. [ABSTRACT FROM AUTHOR]

Forest ecosystems worldwide are subjected to human-induced stressors, including eutrophication and acidification, and to natural disturbances (for example, insect infestation, windstorms, fires). The occurrence of the later is expected to increase due to the ongoing climate change. These multi-stressor forcings modify ecosystem biogeochemistry, including the retention of limiting nutrients, with implications for terrestrial and aquatic biodiversity. Here we present whole ecosystem nutrient (N, Ca, Mg, K) mass balances in the forested catchment of Plešné Lake, CZ, which has undergone transient changes linked to the recovery from anthropogenic acidification and to the forest disturbances caused by severe infestations by the bark beetle (Ips typographus). Measured fluxes and storage of nutrients in the lake-catchment ecosystem were used to constrain the process-oriented biogeochemical model MAGIC (Model of Acidification of Groundwater In Catchments). Simulated lake water chemistry and changes in soil nutrient pools fitted observed data and revealed that (1) the ecosystem N retention declined, thus nitrate leaching increased for 10 years following the bark beetle disturbance, with transient adverse effects on the acid–base status of lake water, (2) the kinetics of nutrient mineralisation from decaying biomass coupled with nutrient immobilisation in regrowing vegetation constrained the magnitude and duration of ecosystem losses of N, Ca and Mg, (3) the excess of mineralised base cations from decomposing biomass replenished the soil cation exchange matrix, which led to increased soil base saturation, and (4) the improvement of the catchment soil acid–base status led to an increase of lake water pH and acid neutralising capacity. Forested ecosystems underlain by nutrient-poor soils and bedrock are prone to human-induced damages caused by acidification and eutrophication, and any natural disturbance may further lead to nutrient imbalances. We demonstrated that in this natural forest ecosystem protected from human intervention, disturbances together with natural post-disturbance vegetation recovery have temporally positive effects on the nutrient stores in the soil. [ABSTRACT FROM AUTHOR]

Acidification has adversely affected freshwater ecosystems in many areas, and recovery from acidification is often interrupted by acidic events. We lack detailed information about how benthic algae react to short-term acidic events and long-term recovery from acidification. We sampled 15 stream sites in the Czech Republic to study the effects of (a) water pH, aluminium and lead concentrations, (b) short-term acidic events, (c) 20 years of recovery from acidification and (d) high phosphorus concentrations combined with low pH on soft-bodied benthic algae. Water pH and aluminium concentrations affected benthic algal assemblages, but the acidification index periphyton (AIP) mainly reflected pH. Benthic algal assemblages reflected recent acidic events more closely than maximum or average pH. Our results indicate that the reaction of benthic algae to pH results from a fast effect of pH minima that cause sensitive species to disappear within a few months, and a slower process of dispersal and competition for resources during periods of higher pH. After an acidic event, recolonization of stream sites by sensitive species had started within 2 years, and was largely completed after 9 years. Our data indicate that acidification may mask the effect of enhanced phosphorus concentrations on benthic algal eutrophication indices. [ABSTRACT FROM AUTHOR]

• Mg/Ca/Sr isotope ratios were measured in 15 sample types from a granitic catchment. • Atmospheric input, bulk rock and runoff had nearly identical Mg and Ca isotope ratios. • Biotite, the main geogenic Mg source, was isotopically too heavy to control runoff Mg. • Ca in apatite and plagioclase was isotopically similar to runoff Ca. • Whole-rock 87Sr/86Sr isotope ratio was too high to control runoff Sr. Magnesium, calcium and strontium isotope systematics were studied in a Central European headwater catchment underlain by granite. The Uhlirska catchment (Czech Republic) is recovering from acidification following 40 years of acid rain. A combination of isotope and non-isotope data was used to constrain the origin of base cations in runoff. Whole-rock δ26Mg, δ44Ca values and 87Sr/86Sr ratios were complemented by isotope analysis of apatite, biotite, plagioclase, orthoclase and titanite. Isotope composition of Mg, Ca and Sr in precipitation, throughfall and runoff was monitored for 12 months. Soil, soil solutions and Norway spruce tissues were also analyzed. Non-isotope data included a 24-year time-series of input/output Mg and Ca fluxes. Biotite was the likely main source of geogenic Mg. Apatite and plagioclase were the likely main sources of geogenic Ca, and plagioclase was the likely main source of geogenic Sr. Magnesium in biotite was isotopically too heavy to dominate runoff. Calcium in apatite and plagioclase was isotopically indistinguishable from whole-rock Ca and could play a major role in runoff generation. Plagioclase had a significantly lower 87Sr/86Sr ratio than bulk bedrock, close to the low 87Sr/86Sr ratio of runoff. Plagioclase weathering was consistent with a sizeable geogenic Sr contribution to runoff but if only bulk-rock 87Sr/86Sr was considered predominance of geogenic Sr in runoff would be unlikely. Higher Mg, Ca and Sr runoff fluxes, compared to deposition, suggested geogenic control of runoff. A decrease in runoff fluxes of Mg and Ca coincided with a decrease in deposition fluxes but there may not be a causal relationship pointing to a large atmospheric contribution of base cations to runoff. Decreasing fluxes of base cations via runoff were mostly related to decreasing sulfate export accompanying retreat of acidification. Mg/Ca/Sr isotope systematics at Uhlirska are discussed in light of analogous data from four other headwater catchments. [ABSTRACT FROM AUTHOR]

A geochemical approach using stable oxygen isotopes was used to understand streamflow generation processes in the highly peaty catchment of the Rokytka Brook in the headwaters of the Vltava River, Czech Republic. The contribution of water from peat bog areas to the total surface runoff was assessed using a hydrological time series, as well as geochemical, hydrochemical and isotope-hydrological approaches for unit hydrogram separation by means of anion deficiency. Using data from the hydrological year 2008, the role of an existing peat bog in the runoff formation dynamics of the Rokytka Brook catchment was determined, and the hydrological cycle was described and assessed using stable18O/16O isotopes. The research findings strongly support the fact that peatland areas within the studied catchment do not significantly communicate hydraulically with surface streams, and their hydrological function in this region is insignificant.Editor M. C. Acreman; Associate editor not assigned [ABSTRACT FROM PUBLISHER]

Evapotranspiration (ET) continues to be a difficult process to estimate in seasonal and long-term water balances in catchment models. Approaches to estimate ET typically use vegetation parameters (e.g., leaf area index [LAI], interception capacity) obtained from field observation, remote sensing data, national or global land cover products, and/or simulated by ecosystem models. In this study we attempt to quantify the uncertainty that spatial evapotranspiration estimation introduces into hydrological simulations when the age of the forest is not precisely known. The Penn State Integrated Hydrologic Model (PIHM) was implemented for the Lysina headwater catchment, located 50°03′N, 12°40′E in the western part of the Czech Republic. The spatial forest patterns were digitized from forest age maps made available by the Czech Forest Administration. Two ET methods were implemented in the catchment model: the Biome-BGC forest growth sub-model (1-way coupled to PIHM) and with the fixed-seasonal LAI method. From these two approaches simulation scenarios were developed. We combined the estimated spatial forest age maps and two ET estimation methods to drive PIHM. A set of spatial hydrologic regime and streamflow regime indices were calculated from the modeling results for each method. Intercomparison of the hydrological responses to the spatial vegetation patterns suggested considerable variation in soil moisture and recharge and a small uncertainty in the groundwater table elevation and streamflow. The hydrologic modeling with ET estimated by Biome-BGC generated less uncertainty due to the plant physiology-based method. The implication of this research is that overall hydrologic variability induced by uncertain management practices was reduced by implementing vegetation models in the catchment models. [ABSTRACT FROM AUTHOR]

Norway spruce ( Picea abies (L.) Karst.) stands in certain areas of Central Europe have experienced substantial dieback since the 1970s. Understanding the reasons for this decline and reexamining the response of forests to acid deposition reduction remains challenging because of a lack of long and well-replicated tree-ring width chronologies. Here, spruce from a subalpine area heavily affected by acid deposition (from both sulfur and nitrogen compounds) is evaluated. Tree-ring width measurements from 98 trees between 1000 and 1350 m above sea level (a.s.l.) reflected significant May–July temperature signals. Since the 1970s, acid deposition has reduced the growth–climate relationship. Efficient pollution control together with a warmer but not drier climate most likely caused the increased growth of spruce stands in this region, the so-called “Black Triangle,” in the 1990s. [ABSTRACT FROM AUTHOR]

Intensive forest management is one of the main land cover changes over the last century in Central Europe, resulting in forest monoculture. It has been proposed that these monoculture stands impact hydrological processes, water yield, water quality and ecosystem services. At the Lysina Critical Zone Observatory, a forest catchment in the western Czech Republic, a distributed physics-based hydrologic model, Penn State Integrated Hydrologic Model (PIHM), was used to simulate long-term hydrological change under different forest management practices, and to evaluate the comparative scenarios of the hydrological consequences of changing land cover. Stand-age-adjusted LAI (leaf area index) curves were generated from an empirical relationship to represent changes in seasonal tree growth. By consideration of age-adjusted LAI, the spatially-distributed model was able to successfully simulate the integrated hydrological response from snowmelt, recharge, evapotranspiration, groundwater levels, soil moisture and streamflow, as well as spatial patterns of each state and flux. Simulation scenarios of forest management (historical management, unmanaged, clear cutting to cropland) were compared. One of the critical findings of the study indicates that selective (patch) forest cutting results in a modest increase in runoff (water yield) as compared to the simulated unmanaged (no cutting) scenario over a 29-year period at Lysina, suggesting the model is sensitive to selective cutting practices. A simulation scenario of cropland or complete forest cutting leads to extreme increases in annual water yield and peak flow. The model sensitivity to forest management practices examined here suggests the utility of models and scenario development to future management strategies for assessing sustainable water resources and ecosystem services.Editor D. Koutsoyiannis [ABSTRACT FROM AUTHOR]

Assessment of temporal trends and rates of change in hydrochemical parameters and forest cover has been conducted to elucidate key drivers of surface water acidification in glacial lakes in the Czech Republic. Since 1984, the key driver in acidification reversal was sulphate (SO 4) concentration (median decrease of −3.58 μeq L −1 yr −1) which fell in line with reductions in sulphur (S) deposition. Reduction of nitrogen (N) deposition was followed by proportional reduction in nitrate (NO 3) leaching although decline in NO 3 concentrations was more pronounced at two sites, the Čertovo Lake (CT) and Prášilské Lake (PR) until 2006; only Žďárské pond showed effective catchment N immobilization. Coherent decline of chloride concentration was detected across all sites. The decrease of strong mineral acids was partly compensated by decrease of inorganic aluminium (Al in), especially at sites most acidified in the beginning of observations (ANC 1984–1986 between −160 and −90 μeq L −1 at CT, Černé Lake—CN and Plešné lake—PL) and by reductions of base cations and increases of pH. All lakes (CN, CT, PL, PR and LK) moved to the ANC range between −29 and 30 μeq L −1 (2010–2012) where sensitivity of pH to further reductions in acid anions may be expected. Concurrently, charge of weak organic acids (OAs) increased and partly balanced the strong mineral acid decrease as a consequence of (i) significant DOC (dissolved organic carbon) increase (median change of 0.13 mgC L −1 yr −1 since 1993) and (ii) deprotonation of weak OAs caused by pH rise. Since 2000s, bark beetle induced forest decline accelerated NO 3 leaching at most of the catchments (by 200 % at LK, PL and PR). However, elevated N leaching was effectively neutralized by base cations (K, Mg, Ca) originating from decaying fresh litter, thus acidification recovery was not reversed, but slowed down. After cessation of NO 3 leaching we hypothesise that collapsed tree canopy across catchments (from 12 to 87 % compared to 1984) will cause lower total acid input in precipitation (S + N) and regrowth of vegetation may stimulate higher N immobilization (in biomass and soil); processes which could lead to further increase of ANC and pH, key indicators for biological recovery. [ABSTRACT FROM AUTHOR]

Elevated and chronic nitrogen (N) deposition to N-limited terrestrial ecosystems can lead to 'N saturation', with resultant ecosystem damage and leaching of nitrate (NO) to surface waters. Present-day N deposition, however, is often a poor predictor of NO leaching, and the pathway of the ecosystem transition from N-limited to N-saturated remains incompletely understood. The dynamics of N cycling are intimately linked to the associated carbon (C) and sulphur (S) cycles. We hypothesize that N saturation is associated with shifts in the microbial community, manifest by a decrease in the fungi-to-bacteria ratio and a transition from N to C limitation. Three mechanisms could lead to lower amount of bioavailable dissolved organic C (DOC) for the microbial community and to C limitation of N-rich systems: (1) Increased abundance of N for plant uptake, causing lower C allocation to plant roots; (2) chemical suppression of DOC solubility by soil acidification; and (3) enhanced mineralisation of DOC due to increased abundance of electron acceptors in the form of $${{\text{SO}}_{ 4}}^{ 2-}$$ and NO in anoxic soil micro-sites. Here we consider each of these mechanisms, the extent to which their hypothesised impacts are consistent with observations from intensively-monitored sites, and the potential to improve biogeochemical models by incorporating mechanistic links to the C and S cycles. [ABSTRACT FROM AUTHOR]

We evaluated how litter raking removed basic nutrients from forest soils by simulating this historical silvicultural practice on two spruce stands ( Picea abies) in the Czech Republic. Experimental litter raking depleted the soil pool of exchangeable base cation nutrients (Ca2+, Mg2+ and K+) by up to 31% after the first litter raking in 2003. A second litter raking in the following year further reduced the soil pool by up to 16%, and the third litter raking in 2005 reduced the pool by up to 6% more. These losses of base cations were substantially greater than their annual input into the forest soil (estimated as from total atmospheric deposition and mineral weathering) as well as their annual runoff. The concentration of Mg and Ca in spruce needless decreased considerably within 3 years from the beginning of the experiment. In addition, the observed litter chemistry was used to estimate historical nutrient removal from litter raking by applying them to historical records of litter removal rates. According to these calculations, the annual loss of total Ca, Mg and K from spruce stands would be from 40% to 100% of its present annual input into the soil, and from 50% to 190% of annual runoff. On the basis of previous results estimated by geochemical modeling, we found that the loss of base cations due to litter raking was similar to their leaching due to acid deposition. We conclude that long-term removal of litter as widely practiced throughout the 19th century in Central Europe may have been responsible for a loss of base cations equivalent to that caused by acid deposition during the 20th century. [ABSTRACT FROM AUTHOR]

Stream nitrogen (N) export and nitrate $$(\text {NO}^-_3) $$ concentration were measured at 14 forested watersheds (GEOMON network) in the Czech Republic between 1994 and 2005. In the last several decades, emissions of sulfur (S) and N compounds have decreased throughout much of Europe. In the Czech Republic, atmospheric deposition of S has decreased substantially since the beginning of 1990s, whereas N deposition remains largely unchanged at most sites. The mean dissolved inorganic nitrogen (DIN) streamwater export ranged from 0.2 to 12.2 kg ha−1 y−1 at the GEOMON sites. Despite decades of elevated N deposition, 44–98% of DIN inputs to these watersheds were retained or denitrified, and many watersheds showed seasonal variation in nitrate concentrations. Dissolved organic N export was quantified in 1 year only and ranged from 0.05 to 3.5 kg ha−1 y−1. Spatial variability in DIN export among watersheds was best explained by spatial variability in average acidic deposition, particularly S deposition ( R 2 = 0.81, P < 0.001); DIN input and forest floor carbon:nitrogen (C/N) also provided significant explanatory power. DIN export was strongly influenced by the forest floor C/N ratio and depth of the forest floor soils ( R 2 = 0.72, P < 0.001). The only variable that predicted variations in forest floor C/N ( R 2 = 0.32, P < 0.05) among watersheds was S deposition. Forest floor depth was also related to deposition variables, with S deposition providing the most explanatory power ( R 2 = 0.50, P < 0.01). Variation in forest floor depth was also associated with climatic factors (precipitation and temperature). Temporal variability in DIN export was primarily associated with changes in acidic deposition over time; S deposition explained 41% of variability in DIN exports among all watersheds and years. Extensive acidification of forested watersheds was associated with the extraordinarily high S inputs to much of the Czech Republic during earlier decades. We hypothesize that recovery from acidification has led to improved tree health as well as enhanced microbial activity in the forest floor. As these watersheds move into a new regime with dramatically lower sulfur inputs, we expect continued declines in nitrate output. [ABSTRACT FROM AUTHOR]

Abstract: During the 1990s the emissions of SO2 fell dramatically by about 90% in the Czech Republic; the measured throughfall deposition of sulphur to a spruce forest at Načetín in the Ore Mts. decreased from almost 50 kg ha−1 in 1994 to 15 kg ha−1 in 2005. The throughfall flux of Ca decreased from 17 kg ha−1 in 1994 to 9 kg ha−1 in 2005; no change was observed for Mg. The deposition of nitrogen ranged between 15 and 30 kg ha−1 with no statistically significant trend in the period 1994–2005. The desorption of previously stored sulphur and the decrease of Ca deposition are the main factors controlling the recovery of soil solution. The pH of the soil solution at a depth of 30 cm remains unchanged, and the Al concentration decreased from 320 μmol l−1 in 1997 to 140 μmol l−1 in 2005. The enhanced leaching of base cations relative to no acidified conditions has continued, although the Ca concentration decreased from 110 μeq l−1 in 1997 to 25 μeq l−1 in 2005 in the mineral soil solution at 30 cm depth. This dramatic change was not observed for Mg concentration in soil solution, because its deposition remained stable during the observed period. Similar patterns were observed in the deeper soil solution at 90 cm. The reduction in Ca availability resulted in lower uptake by tree assimilatory tissues, measured as concentration in needles. Since 2005, the leaching of nitrate observed in soil solution at 30 cm depth has disappeared. By 2003 a similar situation occurred at 90 cm. Higher incorporation into the trees after 1997 could be an important factor. With respect to the formerly high sulphur deposition and consequently released aluminium, which could have negatively influenced the biotic immobilization driven by microbes and fungi, the recovery may have positively impacted and therefore improved retention in the ecosystem during recent years. The delay in the successful retention of nitrogen in the ecosystem was probably caused by the high mineralization of organic matter after improvement of chemical parameters in the organic horizon (increase in pH and decrease in Al concentration). It seems that high mineralization of stored organic matter after decades of high acidic deposition could be an important factor affecting the high losses of nitrogen in spruce forest ecosystems. [Copyright &y& Elsevier]

Dissolved organic carbon and nitrogen (DOC and DON) produced in the forest floor are important for ecosystem functions such as microbial metabolism, pedogenesis and pollutant transport. Past work has shown that both DOC and DON production are related to litterfall and standing stocks of C and N in the forest floor. This study, conducted in spring, 2003, investigated variation in forest floor water extractable DOC (WEDOC) and DON (WEDON) and forest floor C and N as a function of lignin, cellulose and N contained in live canopy foliage across eight Picea abies [L.] Karst stands in northern Bohemia. Based on Near Infrared Spectroscopy (NIR) analysis of foliar materials, lignin:N and cellulose:N content of the youngest needles (those produced in 2002) were positively and significantly related to WEDOC ( R 2 = 0.82–0.97; P<0.01) and to forest floor C:N ratio ( R = 0.72–0.78; P<0.01). Foliar N was strongly and negatively related to WEDOC and C:N ratio ( R = −0.91 and 0.72; P<0.05) among our study sites. WEDON was positively correlated to foliar lignin:N ( R = 0.48; P<0.05; n=40). Forest floor C pools were not positively correlated with foliar lignin and cellulose and forest floor N pools were not positively correlated with foliar N. Instead, a significant negative correlation was found between forest floor N pools and foliar cellulose ( R=−0.41; P<0.05), and between forest floor C pools and foliar N ( R = −0.44; P<0.05). From a remote sensing standpoint, our results are important because canopy reflectance properties are primarily influenced by the most recent foliage, and it was the chemistry of the most recently produced needles that showed a stronger relationship with forest floor WEDOC and C:N ratio suggesting forest floor production of WEDOC can be calculated regionally with remote sensing. [ABSTRACT FROM AUTHOR]

Research has shown that the performance of soil–landform models would improve if the effects of spatial autocorrelation were properly accounted for; however, it remains elusive whether the level of improvement would be predictable, based on the degree of spatial autocorrelation in the model variables. We evaluated this problem using 11 soil variables acquired from the A and B horizons along a hillslope of Žofínský Prales in the Czech Republic. The results showed that, with no exception, there were increases in R2 and decreases in the Akaike information criterion (AIC), residual autocorrelation, and root-mean-square errors (RMSEs), after incorporating the spatial filters extracted by spatial eigenvector mapping into non-spatial regression models. Furthermore, the improvement of the model was positively proportional to the degree of spatial autocorrelation, inherent in the soil variables. That is, there were strikingly linear and significant relationships, in which strongly autocorrelated soil variables (i.e., having a high Moran's I value) exhibited greater increases in R2 and decreases in AIC, residual autocorrelation, and RMSEs than their more weakly autocorrelated counterparts. These findings indicate that the degree of spatial autocorrelation present in soil properties can serve as a direct indicator for how much the performance of a traditional non-spatial soil–landform model would be enhanced, by explicitly taking into consideration the presence of spatial autocorrelation. More generally, our results potentially imply that the need for and benefit from incorporating spatial effects in geopedological modeling proportionally increases as the soil property of interest is more spatially structured (i.e., landform variables alone cannot capture soil spatial variability). • Soil spatial variability was modeled using landform variables in a temperate forest. • In this regression, we included spatial filters as additional independent variables. • This inclusion improved the performance of the original non-spatial approach. • Spatial autocorrelation of soil variables predicted the degree of such improvement. [ABSTRACT FROM AUTHOR]

Recently, data have been required in hydrologic manuscripts. Authors are usually confused by different data management policies. Thus, a frequent response is to write down "data available upon request from the corresponding author". Such a simplified response may lead to dormancy or permanent loss of data. We present an example of data management from a published hydrologic modelling study. We started from figures with complete scientific stories in the publication and traced backwards to find relevant source data through workflows (linking). In this manner the source data can be identified (archiving) and preserved (hosting). Such simple practices of data linking, archiving and hosting can rescue data and require only limited effort by the authors. We suggest that this data rescue process(es) should become routine in scientific publication. The data rescued with workflows can significantly improve the research transparency and reusability, which leads to a fairer and more open culture in hydrology. [ABSTRACT FROM AUTHOR]