Six things that I am going to talk about:

Regenerace lesních ekosystémů z antropogenní acidifikace- dlouhodobý monitoring, experimenty a biogeochemické modelování Filip Oulehle, Jakub Hruška, Pavel Krám, Tomáš Chuman, Oldřich Myška, Tomáš Kolář, Jiří Kopáček, Jack Cosby, Dick Wright, Chris Evans Filip.Oulehle@geology.cz

Six things that I am going to talk about: • Global extent of acid deposition (S and N) • Chemical recovery of surface waters • Effects of acid deposition on forest soil carbon accumulation • Effects of acid deposition on DOC leaching from soils • Effects of acid deposition on forest productivity • Coupled C and N dynamics in MAGIC model

Global extent of sulphur and nitrogen deposition Simulation of future (2030) S deposition using CLE (Current Legislation scenario) Total S deposition (mg m-2 yr-1) 2000 Total N deposition (mg m-2 yr-1) Smith S.J. et al., 2011, ATMOSPHERIC CHEMISTRY AND PHYSICS, 11, 1101–1116 Ratio of total N deposition for scenario CLE (2030) compared to base simulation (2000) 2000 Dentener F. et al., 2006, GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 20, GB4003

K H Mg H Ca Al H Ca H Al Al Mg H Mg H Ca H Ca Al H Mg Na H Al H H2SO4 + BC = (BC)SO4 + 2H+ (1) Al(OH)3 + 3H+ = Al3+ + 3H2O (2) K K K H Mg H Mg K H Mg Ca Acidifikace půd Ca K Ca H Na Na Ca Na H Mg

Chemical recovery of surface waters • Glaciallakes in theSumavaMts. • Monitoring since 1984 Oulehle F., Chuman T., Majer V., Hruška J. (2013). Biogeochemistry 116 (1-3): 83-101.

Chemical recovery of surface waters Hruška J.etal. (2009). Živa4: 189-192.Oulehle F., etal. (2013). Biogeochemistry 116 (1-3): 83-101.

3 Soil Carbon Cycle 4 CO2 Plants litter C respiration 1 2 Dissolved Organic Material (DOM) DOC DON Decomposer Turnover Soil Organic Matter (SOM)

Effects of acid deposition on soil C accumulation • Experimental evidence: • Suppression of litter decomposition under simulated acid (S) deposition (e.g. Pennanen et al., 1998; Persson et al., 1989) • Adverse effect of aluminium on C availability for microorganisms (e.g. Scheel et al., 2007) • pH effect on microbial enzyme activity (e.g. Sinsabaugh, 2010) Al addition (as AlCl3): effects on soil water chemistry Al addition: effects on soil respiration C A2 Mulder J. et al., 2001, WATER, AIR AND SOIL POLLUTION 130: 989-994

Effects of acid deposition on soil C accumulation Long-term evidence: - Across Czech forest catchments (n=14), S bulk deposition explained 32% variability in soil C/N ratio and 50% variability in forest floor depth (Oulehle et al., 2008) Nacetin spruce forest research plot: Wet deposition of sulphur (top) and nitrogen (bottom) in Europe based on the EMEP model Source www.emep.int Oulehle F, Evans C.D., Hofmeister J et al., 2011, GLOBAL CHANGE BIOLOGY 17, 3115-3129

Effects of acid deposition on soil C accumulation • Nacetin spruce forest research plot: • Forest floor C pool reduced by 47% since 1994 • Total S deposition reduced by 77% since 1994 y=-0.133x + 269.83 R2=0.95 dC/dS = 509 Oulehle F, Evans C.D., Hofmeister J et al., 2011, GLOBAL CHANGE BIOLOGY 17, 3115-3129

Conclusions • It appears that past acidification caused the suppression of decomposition leading to the accumulation of a large pool of organic matter on the forest floor. The alleviation of this acidification pressure over the last two decades appears to have triggered the remobilisation of the soil C pool.

Effects of acid deposition on DOC Why is dissolved organic carbon (DOC) important ? • Important feature of many aquatic ecosystems with wide-ranging ecological impacts • Effects on aquatic metabolism as a substrate for heterotrophic production • Influence on primary production through light availability • Resposible for transport of many organic pollutants and heavy metals • Effects on water chemistry, e.g. pH Vinnetou and Plitvice Lakes National Park in Croatia

Why is dissolved organic carbon (DOC) important ? • DOC has increased: • In much of Europe and North America • In lakes and streams • In forests and moorlands • In waterlogged and aerated soils • At high and low flows Prague 2002

Effects of acid deposition on DOC Strong evidence of a relationship between acid deposition and organic matter solubility • Solubility of DOC is dependent on: • Acidity • Ionic strength • Aluminium concentration • Decomposition of organic matter (which produces DOC) also affected by pH, …and N Results from acidity manipulation experiment in UK Acid treatment – H2SO4 Alkaline treatment - NaOH + MgCl2 Temporal coherence between SO4 declines and DOC increases in Central European catchments Consistent, positive DOC response to pH change at all sites, which can be described by a simple, general relationship, such that a 1 unit increase in soil solution pH is sufficient to more than double DOC concentrations. Oulehle F. and Hruska J., 2009, ENVIRONMENTAL POLLUTION 157: 3433-3439 Evans C.D. ,2012, GLOBAL CHANGE BIOLOGY 18: 3317-3331

Linkages between DOC availability and soilheterotrophicrespiration Threemechanisms could lead to lower amount of bioavailabledissolved organic C (DOC) for the microbialcommunity (Kopáček et al., 2013) Increased abundance of N for plant uptake, causinglower C allocation to plant roots Chemicalsuppression of DOC solubility by soil acidification (3) Enhancedmineralisation of DOC due toincreased abundance of electron acceptors inthe formof sulphateand nitrate- in anoxic soil micro-sites. CO2measurements Treatmentaddition Treatmentaddition Treatmentaddition Week 1 Week 2 Week 3 Week 4 Leachateanalysis Leachateanalysis Leachateanalysis Soilanalysis Soilanalysis 800 ueq L-1 H2SO4 HCl NaOH NaCl Control

Linkages between DOC availability and soil heterotrophic respiration

Linkages between DOC availability and soil heterotrophic respiration Solution applications had immediate effect on DOC concentration in soil water.

Linkages between DOC availability and soil heterotrophic respiration Solution applications had immediate effect on DOC concentration in soil water and on soil respiration. In the end of the experiment, alkaline solution enhanced soil respiration by 20% compared to control, whereas acid treatment suppressed soil respiration by 15% compared to control. Neutral treatment has only short-term effect (suppression) on soil respiration.

Conclusions • It appears that past acidification caused the suppression of decomposition leading to the accumulation of a large pool of organic matter on the forest floor. The alleviation of this acidification pressure over the last two decades appears to have triggered the remobilisation of the soil C pool. • Declining S deposition appears able to explain a large part of observed DOC trends. • Therefore, rising DOC in well studied areas (Europe, USA) should not be misconstrued as evidence of rising DOC in unmonitored waters globally. • - threats of widespread destabilization of terrestrial carbon reserves by gradual rises in air temperature or CO2 concentration may have been overstated in those areas. • Past acid conditions may have reduced decomposition rates, allowing a pool of relatively labile organic matter to accumulate, from which DOC is generated as acidity decreases.

Tree ring increments (forest productivity) over the last century Mean N deposition (bulk) 1994-2013 13 kg N/ha/year Mean S deposition (bulk) 1994-2013 10 kg S/ha/year Mean N-NO3 leaching 1994-2013 6kg N/ha/year n = ≈100 Tree line data since 1690 (V. Treml, unpublished results) Elevation 1000 - 1300 m a.s.l. Precipitation ≈1750 mm

Conclusions • It appears that past acidification caused the suppression of decomposition leading to the accumulation of a large pool of organic matter on the forest floor. The alleviation of this acidification pressure over the last two decades appears to have triggered the remobilisation of the soil C pool. • Declining S deposition appears able to explain a large part of observed DOC trends. • Therefore, rising DOC in well studied areas (Europe, USA) should not be misconstrued as evidence of rising DOC in unmonitored waters globally. • - threats of widespread destabilization of terrestrial carbon reserves by gradual rises in air temperature or CO2 concentration may have been overstated in those areas. • Past acid conditions may have reduced decomposition rates, allowing a pool of relatively labile organic matter to accumulate, from which DOC is generated as acidity decreases. • Altered soil respiration is probably a direct result of DOC bioavailability for microbes under different treatments, rather then direct pH effect on soil microbial communities. • Growth reduction of conifer forests in Central Europe has been observed between the 1960s and 1980s. • During recent decades a distinct increasing growth trends were observed. This trend might only be explained if climate, fertilization by N-deposition, and the strong reduction of SO2 pollution are taken into account.

Modelling nitrogen with MAGIC • MAGIC (Model for Acidification of Groundwater In Catchments) • Developed to predict the long-term effects of acidic deposition on surface water chemistry • Model simulates soil and surface water chemistry in response to changes in drivers such as deposition of S and N, land use practices, climate… • As sulphate concentrations have decreased, in response to the decreased S deposition, nitrate (NO3) has become increasingly important. In acid soils much of the NO3 leached from soil is accompanied by the acid cations H+ and inorganic aluminium (Ali) • In the early versions of MAGIC (version 1-5) retention of N was calculated empirically as a fraction of N deposited from input-output budgets • Later on fraction N retained was described as a function of the N richness of the ecosystem (soil C/N ratio in this case) – version 7

Soil C/N and N leaching - empirical evidence Soil C/N seems to be a good predictor of N leaching on a spatial scale Lovett et al., Ecosystems (2002) 5: 712-718 • Some limitations • Soil C/N is vegetation specific • C/N ratio does not necessarily reflect the N-richness of the actively cycling • component of the organic matter • C/N ratio does not appear to be useful in understanding relatively short-term changes in N dynamics • „hard“ to detect changes in soil C/N under field conditions Oulehleet al. Ecosystems (2008) 11: 410–425

Modelling nitrogen with MAGIC Alternative formulation of N retention in new version of MAGIC (MAGIC v7ext) is based directly on the microbial processes which determine the balance of N mineralization and immobilization. Conceptually developed by Jack Cosby • Inorganic N enters the model as deposition (wet and dry) • Time series of plant litter and N fixation (litter C and N) are external inputs to SOM. At each time step, decomposers process some of the C and N content of SOM (FC1 and FN1). A portion of this C and N turnover returns to the SOM as decomposer biomass (FC2 and FN2), while the remainder is lost from SOM as CO2 and NH4 (FC3 and FN3) or as DOC and DON (FC4 and FN4).

Modelling nitrogen with MAGIC • Preliminary testing of MAGIC performance in monthly time step • Soil organic matter decomposition and N uptake driven by changes in soil temperature – Q10 fce (calculated externaly) • potential application in climate change scenario assessment Čertovo lake

Modelling nitrogen with MAGIC

Conclusions • It appears that past acidification caused the suppression of decomposition leading to the accumulation of a large pool of organic matter on the forest floor. The alleviation of this acidification pressure over the last two decades appears to have triggered the remobilisation of the soil C pool. • Declining S deposition appears able to explain a large part of observed DOC trends. • Therefore, rising DOC in well studied areas (Europe, USA) should not be misconstrued as evidence of rising DOC in unmonitored waters globally. • - threats of widespread destabilization of terrestrial carbon reserves by gradual rises in air temperature or CO2 concentration may have been overstated in those areas. • Past acid conditions may have reduced decomposition rates, allowing a pool of relatively labile organic matter to accumulate, from which DOC is generated as acidity decreases. • Altered soil respiration is probably a direct result of DOC bioavailability for microbes under different treatments, rather then direct pH effect on soil microbial communities. • Growth reduction of conifer forests in Central Europe has been observed between the 1960s and 1980s. • During recent decades a distinct increasing growth trends were observed. This trend might only be explained if climate, fertilization by N-deposition, and the strong reduction of SO2 pollution are taken into account. • Acidity changes in forest ecosystems might have a strong confounding influence on ecosystem sensitivity to eutrophication, with acidification accelerating N saturation (nitrate leaching), and recovery potentially resulting in reversion to N limitation (nitrate retention).

Conclusions • It appears that past acidification caused the suppression of decomposition leading to the accumulation of a large pool of organic matter on the forest floor. The alleviation of this acidification pressure over the last two decades appears to have triggered the remobilisation of the soil C pool. • Declining S deposition appears able to explain a large part of observed DOC trends. • Therefore, rising DOC in well studied areas (Europe, USA) should not be misconstrued as evidence of rising DOC in unmonitored waters globally. • - threats of widespread destabilization of terrestrial carbon reserves by gradual rises in air temperature or CO2 concentration may have been overstated in those areas. • Past acid conditions may have reduced decomposition rates, allowing a pool of relatively labile organic matter to accumulate, from which DOC is generated as acidity decreases. • Altered soil respiration is probably a direct result of DOC bioavailability for microbes under different treatments, rather then direct pH effect on soil microbial communities. • Growth reduction of conifer forests in Central Europe has been observed between the 1960s and 1980s. • During recent decades a distinct increasing growth trends were observed. This trend might only be explained if climate, fertilization by N-deposition, and the strong reduction of SO2 pollution are taken into account. • Acidity changes in forest ecosystems might have a strong confounding influence on ecosystem sensitivity to eutrophication, with acidification accelerating N saturation (nitrate leaching), and recovery potentially resulting in reversion to N limitation (nitrate retention). Děkuji za pozornost

MODELOVÁNÍ • Oulehle F., Cosby B.J., Wright R.F., Hruška J., Kopáček J., Krám P., Evans C.D., and Moldan F. (2012). Modeling soil nitrogen: the MAGIC model with nitrogen retention linked to carbon turnover using decomposer dynamics. Environmental Pollution 165: 158-166. Rowe E.C., Tipping E., Posch M., Oulehle F., Cooper D.M., Jones T.G., Burden A., Hall J., Evans C.D. (2014). Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter. Environmental Pollution184: 271-282. ACIDIFKACE POVRCHOVÝCH VOD Oulehle F., Chuman T., Majer V., Hruška J. (2013). Chemical recovery of acidified Bohemian lakes between 1984 and 2012: The role of acid deposition and bark beetle induced forest disturbance. Biogeochemistry 116 (1-3): 83-101. ROZPUŠTĚNÝ ORGANICKÝ UHLÍK Oulehle F., Jones T.G., Burden A., Cooper M.D.A., Lebron I., Zieliński P., Evans C.D. (2013). Soil-solution partitioning of DOC in acid organic soils: Results from a UK field acidification and alkalization experiment. European Journal of Soil Science 64 (6): 787-796. • Oulehle F. and Hruška J. (2009) Rising trends of dissolved organic matter in drinking-water reservoirs as a result of recovery from acidification in the Ore Mts., Czech Republic. Environmental Pollution 157: 3433-3439. • Evans C.D., Jones T.G., Burden A., Ostle N., Zielinski P., Cooper M.D.A., Peacock M., Clark J.M., Oulehle F., Cooper D., Freeman C. (2012). Acidity controls on dissolved organic carbon mobility in organic soils. Global Change Biology 18: 3317-3331. VZTAH MEZI ACIDIFIKACÍA C A N KOLOBĚHEM V LESNÍCH PŮDÁCH • Oulehle F., Evans C.D., Hofmeister J., Krejci R., Tahovska K., Persson T., Cudlin P., Hruska J. (2011) Major changes in forest carbon and nitrogen cycling caused by declining sulphur deposition. Global Change Biology 17: 3115-3129. Kopáček J., Cosby B.J., Evans C.D., Hruška J., Moldan F., Oulehle F., Šantrůčková H., Tahovská K., Wright R.F. (2013). Nitrogen, organic carbon and sulphur cycling in terrestrial ecosystems: Linking nitrogen saturation to carbon limitation of soil microbial processes. Biogeochemistry 115 (1-3): 33-51. Tahovská K., Kaňa J., Bárta J., Oulehle F., Richter A., Šantrůčková H. (2013). Microbial N immobilization is of great importance in acidified mountain spruce forest soils. Soil Biology & Biochemistry 59: 58-71

Six things that I am going to talk about: