Peat Ash Research Articles

ВОССТАНОВЛЕНИЕ РАСТИТЕЛЬНОСТИ И ПОЧВЕННОГО ПОКРОВА НА НАЧАЛЬНОЙ СТАДИИ ЗАРАСТАНИЯ ГАРЕЙ НА ВЫРАБОТАННЫХ ТОРФЯНИКАХ, "Лесоведение"

RUSSIAN JOURNAL OF FOREST SCIENCE. 2018. NO. 2. P. 119-129. VEGETATION AND SOIL COVERS AT EARLY STAGE OF POST-FIRE RECOVERY IN EXTRACTED PEATLANDS N. P. Akhmet’eva 1 , A. V. Mikhailova 2 , L. P. Fedorova 3 1 Water Problems Institute, Russian Academy of Sciences Gubkin st. 3, Moscow, 119333, Russia E-mail: nakhmeteva@rambler.ru 2 Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences Kosygin st. 19, Moscow, 119991, Russia 3 Berg State Researh Institute on Lake and River Fisheries Gagarina st. 14, Konakovo, Tver Oblast, 171254, Russia Received 12 April 2016 Recovery of vegetation and soil covers after fire in 2010 was studied during summer on drained peatland sites Galitskii Mokh (Tver Oblast) and Radovitskii Mokh (Moscow Oblast), which has been filled with water in 2012-13. By the year 2015 we have found the following. Grass and wooden vegetation recovered intensively for 2-3 years after fire. Birch, willow and cottongrass community with alder and aspen, and little abundance of pine on Radovitskii Mokh, have formed by the time of study. Chemical composition of peat ash and pyrogenic peat has changed essentially and differently on the sites. However concentration of chemical elements under study has not reached the pre-fire values. Chemical composition of wetland waters on Radovitskii Mokh has become similar to pre-fire. On the other hand, wetland waters on Galitskii Mokh still have contained high concentrations of sulfates and phosphorus. Keywords: drained wetlands, peat fires, vegetation recovery, hydrochemical indicators in ash, pyrogenic peat, wetland waters. DOI: 10.7868/S0024114818020043 REFERENCES Akhmet'eva N.P., Belova S.E., Dzhamalov R.G., Kulichevskaya I.S., Lapina E.E., Mikhailova A.V., Natural post-fire bog recovery, Water Resources , 2014, Vol. 41, No. 4, pp. 353–363. Akhmet'eva N.P., Mikhailova A.V., Pozhary 2010-2011 gg. na bolote Radovitskii Mokh i ikh posledstviya (Consequences of 2010-11 fires on Radovitskii Mokh bog), Monitoring i sokhranenie osobo tsennykh prirodnykh territorii i obektov Vladimirskoi oblasti i sopredel'nykh regionov: problemy, opyt i perspektivy (Monitoring and conservation of outstanding natural resources lands and sites in Vladimir Oblast and the neighbouring regions: Challenges, experience and perspectives) Vladimir, 14-15 December 2012, Vladimir: Tranzit-IKS, 2013, pp. 14-18. Atrokhin V.G., Kuznetsov G.V., Lesovodstvo (Silviculture), Moscow: Agropromizdat, 1989, 400 p. Gromtsev A.N., Dinamika korennykh taezhnykh lesov Evropeiskoi chasti Rossii pri estestvennykh narusheniyakh (Dynamics of intact forests in taiga of European part of Russia under natural disturbance), Aktual'nye problemy geobotaniki (Urgent challenges of geobotany), Petrozavodsk, 24-28 September 2007, Petrozavodsk: Izd-vo KarNTs RAN, 2007, pp. 283-301. Gubanov I.A., Novikov V.S., Tikhomirov V.N., Opredelitel' vysshikh rastenii srednei polosy Evropeiskoi chasti SSSR (Key to higher plants of the Center of the European part of the USSR), Moscow: Prosveshchenie, 1981, 287 p. Korchagin A.A., Vliyanie pozharov na rastitel'nost' i vosstanovlenie ee posle pozhara na Evropeiskom Severe (The effect of fires on vegetation: recovery after fire in Northern Europe), Trudy Botanicheskogo instituta im. V.L. Komarova Akademii nauk SSSR. Seriya 3: Geobotanika , 1954, No. 9, pp. 75-149. P'yavchenko N.I., Lesnoe bolotovedenie: osnovnye voprosy (Forest paludology: basic issues), Moscow: Izd-vo AN SSSR, 1963, 192 p. Panov V.V., Tsymlyakova S.S., Prostranstvennaya struktura pozharov i gari na tekhnogenno narushennykh torfyanykh bolotakh (Spatial structure of fires and burnt areas in the technologically disturbed peat bogs), Izvestiya Russkogo geograficheskogo obshchestva , 2013, Vol. 145, No. 1, pp. 80-90. Sirin A.A., Minaeva T.Y., Vozbrannaya A.E., Bartalev S.A., Kak izbezhat' torfyanykh pozharov? (How to avoid peat fires?), Nauka v Rossii , 2011, No. 2, pp. 13-21.

Effects of Soil Conditioners on Aggregate Stability in a Clay Loam Soil: A Comparison Study of Biomass Ash with Other Four Conditioners

ABSTRACTThis study was conducted to investigate the effects of soil conditioners on the structure stability of degraded soil. Biomass ash, lime, lime with zeolite, biological fertilizer and peat ash, mixed with chemical fertilizer were selected as soil conditioners. A pot experiment with degraded clay loam soil (a Cambisol) was carried out. The stability of soil aggregates was analyzed by the Le Bissonnais method. The results showed that macro-aggregates (>0.25 mm) of biomass ash treatment in fast wetting test stayed stable compared with others. The higher mean weight diameter and geometrical mean diameter in biomass ash treatment indicated a high stability from external forces. From this study, the stability of soil aggregates was improved by the addition of biomass ash in degraded soil effectively, but more attention should be paid on soil slope protection during heavy-rain seasons.

Impacts of peat bulk density, ash deposition and rainwater chemistry on establishment of peatland mosses

Background and aimsPeatland moss communities play an important role in ecosystem function. Drivers such as fire and atmospheric pollution have the capacity to influence mosses via multiple pathways. Here, we investigate physical and chemical processes which may influence establishment and growth of three key moss species in peatlands.MethodsA controlled factorial experiment investigated the effects of different peat bulk density, ash deposition and rainwater chemistry treatments on the growth of Sphagnum capillifolium, S. fallax and Campylopus introflexus.ResultsHigher peat bulk density limited growth of both Sphagnum species. S. capillifolium and C. introflexus responded positively to ash deposition. Less polluted rain limited growth of C. introflexus. Biomass was well correlated with percentage cover in all three species.ConclusionsPeat bulk density increases caused by fire or drainage can limit Sphagnum establishment and growth, potentially threatening peatland function. Ash inputs may have direct benefits for some Sphagnum species, but are also likely to increase competition from other bryophytes and vascular plants which may offset positive effects. Rainwater pollution may similarly increase competition to Sphagnum, and could enhance positive effects of ash addition on C. introflexus growth. Finally, cover can provide a useful approximation of biomass where destructive sampling is undesirable.

Assessment of radiological efficiency of countermeasures on peat-bog soils of Ukrainian Polissya

In the field conditions, the long-term (2013–2015) small-plots experiment was carried out for evaluation of radiological efficiency of application of ameliorants as the countermeasures for reduction of the 137Cs uptake to herbage at the Peat-boggy (Histosols) soils of Ukrainian Polissya. At the late stage after the Chernobyl accident, the average radiological efficiencies of application of sand (175–200 ton ha−1) and ferrocyn (0.2 ton ha−1) as the ameliorants were rather low ranging from 0.8 to 1.6. Application of 4 ton ha-1 of chalk and 5 ton ha-1 of peat ash decreased 1.7–1.9 times the 137Cs activity concentrations in plans. The highest radiological efficiencies, 4.4 ± 2.0 and 7 ± 2, were reached at applications of chalk-ferrocyn ameliorant (4 + 0.2 ton ha−1) and ferrocyn-bentonite absorbent HZH-90 (30 ton ha−1), respectively.

P-06 泥炭とバイオマス混合灰の溶融特性(熱分解・ガス化,ポスター発表)

P-06 泥炭とバイオマス混合灰の溶融特性(熱分解・ガス化,ポスター発表)

Compressibility Characteristics of Compacted Clay Treated with Cement, Peat Ash and Silica Sand

This paper investigates the compressibility characteristics of compacted clay treated with cement, peat ash and silica sand. For this purpose, one dimensional consolidation tests were conducted to determine the soil consolidation properties. The test specimens were trimmed from the compaction test specimen. The 1D consolidation test specimen was subjected to the normal pressures of 2.5, 5, 10, 20, 40, 80 and 160 kPa in sequence on the test specimen which was saturated with distilled water. At the end of the loading period of 80 kPa, the vertical load was removed and the specimen was allowed to expand for 24 h for the purpose of evaluating of its swelling behavior. The results showed that void ratio of the soil specimens decreased with increasing effective normal pressure. The laboratory investigation clearly demonstrates that, settlement is as the compression of a soil specimen due to vertical loading applied at the top surface of the 1D consolidation test specimen. It was concluded that, the compression settlement of the stabilized soil with the binder composition of 18% cement, 2% peat ash and 5% silica sand improved by almost 1.3-fold. A notable discovery is the suitability of the stabilized soil for road embankment and low lying marginal area for foundation works; also solving the environmental problems in relation to peaty ground. However, sufficient laboratory and field testing are required.

Attenuation of pollution arising from acid mine drainage by a natural wetland on the Witwatersrand


 
 
 Wetlands are well known to be efficient at sequestering pollutants from contaminated water. We investigated metal accumulation in the peats of the Klip River, a natural wetland that has received contaminated water from gold mining operations in Johannesburg for over 130 years. Previous work conducted in the downstream portion identified the wetland as an important system for sequestering metals. We focused on the upstream section of the wetland, more proximal to the source of acid mine drainage, to provide a better understanding of the pollutant sources and the role of the wetland in pollutant attenuation. Geochemical and mineralogical analyses of peat cores revealed considerable metal enrichments in the peat ash, particularly in Co, Ni, Zn, Pb, Cu and U. Metal concentrations are typically between 4 to 8 times higher than those previously reported for the downstream, more distal portion of the wetland. The distribution of metal accumulation within the peat profiles suggests that contamination arises from a combination of sources and processes. Elevated concentrations in the shallow peat are attributed to the input of contaminated surface water via tributaries that drain the Central Rand Goldfield, whereas enrichments in the deeper peat suggest significant sub-surface inflow of contaminated water through the underlying dolomitic rocks. Metal immobilisation occurs through a combination of mechanisms, which include the precipitation of gypsum, metal sulfides, Fe-Mn oxyhydroxides and phosphates. Our study highlights the environmental and economic importance of natural wetland systems which have the ability to accumulate large quantities of metals and thus remediate polluted waters.
 
 
 
 
 Significance: 
 
 
 
 Considerable levels of metal accumulation are observed within the Klip River wetland peats.
 The wetland is effective in remediating highly polluted water emanating from the Witwatersrand Basin.
 The Klip River system is important for the region’s future water supply.
 
 
 

Comparative measurement of compaction impact of clay stabilized with cement, peat ash and silica sand

Abstract This paper concentrates on measuring the compact ability of Taman Wetland clay stabilized with cement, peat ash and silica sand. The organic content of peat makes it a problematic basement soil for highway construction. Such problem can be solved by removing and incinerating the peat for generating peat ash which is applicable for stabilization of the compacted clay. Compaction tests were conducted on both untreated and stabilized clay specimens. The mix designs from the compaction tests were applied on stabilized clay specimens for testing using direct shear apparatus. A feasible mix design can be developed by partially replacing the cement with 1.5% peat ash in the test specimens. Test specimen with the mix design has the highest cohesion of 133 kPa as compared to those of test specimens with other mix designs under study. Such cohesiveness is attributable to the formation of cementation crystals which effectively clogged the pore spaces of the stabilized clay.

Stabilization of compacted clay with cement and/or lime containing peat ash

Soft clay is problematic due to its settlement, swelling and strength issues, when applied as road embankment material. This paper investigates the possibility of the use of cement and/or lime for improvement ground of shallow clay to support highway embankment. A novel approach to stabilize the clay is to use peat ash as a supplementary material in the compacted and stabilized soil. It is worth noting that research on the application of peat ash as a pozzolanic material in stabilizing soft clay is relatively scarce. The objectives of this research are: (i) to stabilize the compacted clay with cement and/or lime, peat ash and silica sand in the laboratory and (ii) to evaluate the effect of binder dosages on short-term and long-term strength of stabilized soil. To this end, the stabilized soil specimens with the highest maximum dry density were chosen for further evaluation under laboratory unconfined compression tests. In addition, the chemical compositions of materials and microstructure of the stabilized clay were examined using X-ray Fluorescence and Scanning Electron Microscope (SEM), respectively. It was found that, the optimal mix design of the stabilized soil is 14% cement, 12% peat ash and 5% silica sand. SEM analysis suggests that the cementitious products were increased with cement and peat ash dosages and clogged the pore spaces. It was further revealed that, partial replacement of cement with 12% peat ash in the optimal mix design resulted in maximum unconfined compressive strength. In summary, a notable discovery is that the partial replacement of cement with 12% peat ash in the optimal mix design can be sustainably applied in order to stabilize the clay without failure. Meanwhile, it has been observed that cement content higher than the lime content enables a better homogeneity of the stabilization, enhancing the strength development in the stabilized soil.

Permeability Characteristics of Compacted and Stabilized Clay with Cement, Peat Ash and Silica Sand

The present paper investigates the influence of stabilization with cement, peat ash, and silica sand on permeability coefficient (kv) of compacted clay, using a novel approach to stabilize the clay with peat ash as a supplementary material of cement in the compacted and stabilized soil. In order to assess the mentioned influence, test specimens of both untreated and stabilized soil have been tested in the laboratory so that their permeability could be evaluated. Falling head and one dimensional consolidation tests of laboratory permeability were performed on the clay specimens and the chemical compositions of the materials as well as microstructure of the stabilized soil with 18% cement, 2% peat ash, and 5% silica sand were investigated, using X-ray fluorescence and scanning electron microscopy respectively. Results show that for soil stabilization with up to 8% cement content (of the dry weight of the soil), the average value of coefficient of permeability (kv) is very close to that of untreated soil, whereas the kv value decreases drastically for 18% cement under identical void ratio conditions. It is further revealed that addition of 18% cement, 2% peat ash, and 5% silica sand had decreased the coefficient of permeability by almost 2.2 folds after 24 h, while about 1.7 folds increase was observed in coefficient of permeability once 13.5% of cement, 1.5% of peat ash, and 20% of silica sand were added. The partial replacement of cement with the 2% peat ash can reduce the consumption of cement for soil stabilization.

Synthesis and characterization of high density polyethylene/peat ash composites

Abstract A new type of polymer composite was synthesized from peat ash which was obtained as industrial waste. This was added to high density polyethylene (HDPE) at varying mixing ratios and the resulting products were characterized using different experiments which included Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), melt flow index (MFI), density, wettability, tensile test, flexural test and cost analysis. The effects of various ash loadings and the use of the maleic anhydride grafted high density polyethylene (HDPE-g-MA) compatibilizer on the physical and mechanical properties of composites were investigated. It was observed that the utilization of peat ash significantly increased the tensile strength and the flexural modulus, where also reducing raw material cost. Incorporating (HDPE-g-MA) in the composites formulation led to further increases in tensile and flexural properties. Conversely, there was a significant decrease of impact strength found for all composites in comparison to the virgin HDPE. And the impact strengths generally decreased as peat ash content increases. Microstructural analyses showed that surface treated peat ash particles appeared to be well-incorporated into the HDPE matrix, as intimated polymer/peat ash contact was observed. In addition, the melt flow index of the composites decreased remarkably with an increase in peat ash content. No significant water uptake effect was detected on peat ash composites indicating that these materials could be used as a direct replacement for HDPE in applications where impact strength is not a critical factor. Furthermore, the use of peat ash increased the composite density in comparison to virgin HDPE. Nevertheless, as peat ash reinforcement does offer increased tensile and flexural properties, this may make the end product lighter as lower wall thickness parts can be used to fulfil the same function. From this study, it was concluded that the utilization of the peat ash from peat fired power stations has proved to have significant value-added potential as a filler material in polymer composites.

Long-term effect of wood and peat ash on the growth of Pinus sylvestris on drained peatland

The effect of ash fertilization on height growth and volume production of Scots pine (Pinus sylvestris L.) was studied on oligotroph peatland in southeast Norway. In the year 1944, plots 15 m × 15 m size were fertilized with 0, 4, 7, and 10 tons ha−1 of wood or peat ash. The area was treeless, but a satisfactory number of pine seedlings were present. All measurements were confined to the central inner plot, 10 m × 10 m area. Most plots were re-fertilized with 10 tons of wood ash ha−1 in the year 1993. Wood ash had higher content of nutrients, and generally, it had greater growth enhancement effect than peat ash. When the amount of ash was increased, volume production significantly increased for the age period 38–50 years and the total production at age 50 years. The mean annual increment during the first 50 years was about 6 m3 ha−1 for the plots applied with 10 tons of ash ha−1. Trees on plots fertilized with 7 or 10 tons in 1944 and replenished with 10 tons ha−1 at age 50 years (1993) had a mean annual increment of 14 m3 ha−1 for the stand age period 51–68 years. Over time some tree roots from control plots and plots fertilized with 4 tons ha−1 have captured nutrients from richer plots. Such effect is to a smaller extent relevant for treatment 7 tons. It is concluded that the content of mineral nutrients of wood and peat ash makes these ashes well suited as fertilizers on peatland.

Natural post-fire bog recovery

The dynamics of natural recovery of bog massifs in Tver oblast, which suffered from fire in 2010, is discussed. The presented conclusions are based on three-year field observations at check sites of Galitskii mokh bog along with monitored variations of the physicochemical properties of peat ash and pyrolyzed peat, bog water chemistry, the development of microbial communities, and vegetation recovery. Moreover, some features of bog massif flooding are discussed.

Influence of Peat Ash Composition on Particle Emissions and Slag Formation in Biomass Grate Co-combustion

Co-combustion by fuel blending of peat and biomass has shown positive effects on operational problems. However, peat ash compositions vary considerably, and this has been shown to affect the potential for operational problems in different fuel-blending situations. The present work used three different peat types with the objective to elucidate how the variation in peat ash composition influences both particle emissions and slag formation during co-combustion with three different biomasses in a small-scale pellet boiler. Estimations of potassium release and slag formation were performed and discussed in relation to fuel composition in the (K2O + Na2O)–(CaO + MgO)–(SiO2) system. All tested peat types reduced the fine particle emissions by capturing potassium into the bottom ash as one or several of the following forms: slag, sulfates, chlorides, and alumina silicates. However, there were considerable differences between the peat types, presumably depending upon both their content and mineral composition of silicon, calcium, aluminum, and sulfur. Some general important and beneficial properties of peat type in co-combustion situations with biomass are defined here, but the specific blending proportion of peat should be decided on an individual basis for each scenario based on the relative contents in the fuel mixture of the most relevant ash-forming elements.

Treatment of wood leachate with high polyphenols content by peat and carbon-containing fly ash filters

In the present study, two combinations of filter materials in filter/columns were examined for removal of total organic carbon (TOC) and polyphenols (PP) found in storm water runoff from wood storage areas in a wooden floor industry. One filter/column was packed with peat mixed with carbon-containing fly ash, while another filter/column contained only peat (without ash). The mixture of peat and ash has shown faster and higher removal capacity for TOC and faster removal with the same final removal capacity for PP (in grams of pollutant per kg of sorbent) at the saturation point. The superiority observed for the peat and ash filter is presumably due to the unique characteristics of peat and ash, which enhanced the treatment efficiency when used together in a mixture. Based on the observed results, filters formed by peat and carbon-containing ashes proved to be a potentially low-cost option for the treatment of storm water generated at storage areas of wood materials such as logs, sawdust and wood chips.

Influence of oil and stratal water contamination on the ash composition of oligotrophic peat soils in the oil-production area (the Ob’ region)

The mineral contamination of peat soils in the oil-production area differs considerably in the places of oil or stratal water spills. The time elapsed since the spill occurred is also an important factor of the changes in the chemical composition of the peat ash. The ash content rises drastically in the oil-contaminated peat, and the peat ash becomes rich in heavy metals (Mn, Ni, and Sr) and lanthanides (La and Ce). The content of K and Fe decreases, and that of P, S, Mg, Ca, Ni, and Pb increases with time at the site of old oil contamination. In the course of the self-rehabilitation of oil-contaminated peat, the content of Cl decreases more intensely than that of the heavier halogen Br. The ash content rises to a lesser extent in the peat contaminated with stratal water. The ash of the salinized peat is enriched in heavy alkaline-earth elements, i.e., Ba and Sr. Although most of the elements are leached with time, the content of Ba and Sr still remains 4–6 times higher than the background one even after long-term (more than 10 years) leaching. The concentrations of halogens rise considerably in the salinized peat, that of Cl in the peat ash decreases by 10 times, and the content of Ba virtually remains the same.

Controlling CO<sub>2</sub> and CH<sub>4</sub> Emission in a Degraded Peat Swamp Forest Related to Water Table and Peat Characteristics

This study focuses on factors controlling CO2and CH4emission in a peat swamp forest related to water table and peat characteristics such as peat depth, C-organic, pH, ash content and N-total. This study was conducted in the dry season at a Merang peat swamp forest that has degraded due to logging activities, forest fires and canal opening. Emission of CO2and CH4was measured by using a closed chamber made by PVC material (60 cm x 60 cm x 40 cm). This close chamber was completed with a fan inside the chamber to stir the gas, a thermometer inside the chamber to measure the gas temperature and a syringe to sample gas. This study has shown that the highest CO2emission is at an average of 438.93 mg/m2/hr occurring in land cover type (1) ferns and grasses (open burned area) and the lowest is at average of 44.45 mg/m2/hr in thegelamandbelidang-dominated land. The emission of CH4is very low between 0.0018 to 0.0069 mg/m2/hr. the main controlling factor on CO2and CH4emission is concluded to be the water table. The emission of CO2will be greater if water table, pH and C-organic increase.

The Vikings were not the first colonizers of the Faroe Islands

We report on the earliest archaeological evidence from the Faroe Islands, placing human colonization in the 4th–6th centuries AD, at least 300–500 years earlier than previously demonstrated archaeologically. The evidence consists of an extensive wind-blown sand deposit containing patches of burnt peat ash of anthropogenic origin. Samples of carbonised barley grains from two of these ash patches produced 14C dates of two pre-Viking phases within the 4th–6th and late 6th–8th centuries AD. A re-evaluation is required of the nature, scale and timing of the human colonization of the Faroes and the wider North Atlantic region.

Rare earth elements in the peats of Moscow and Tver oblasts

Noticeable amounts of rare-earth elements were first detected in the peats of the earlier drained bogs of Moscow and Tver oblasts. The analysis was carried out by inductively coupled plasma mass spectrometry on an ELAN DRC II instrument (PerkinElmer, United States). The contents of REEs in peat ash of certain deposits are higher than their average contents in the basic rocks and vary in the range of 0.5–60 and 0.1–41.3 mg/kg for the cerium and yttrium groups, respectively.

Long-term effects of ash fertilization on runoff water quality from drained peatland forests

The increasing use of wood and peat in energy production has created a potential to utilize wood and peat ashes as forest fertilizers on a wide scale. Previous studies have shown that tree growth in peatland benefits most from ash fertilization. However, possible harmful effects on recipient watercourses have prevented any larger-scale fertilization activity. The objective of this study was to examine the long-term changes in runoff acidity and the transport of nutrients, heavy metals and dissolved organic carbon via drainage water from drained boreal peatland catchments fertilized with wood or peat ash. The hypotheses were that the site’s peat type, the origin and formula of the ash and the time of application have an influence on leaching amounts. Therefore, the studied catchments represented different peat (Carex or Sphagnum) and site types with different standing tree stocks (8–127m3ha−1). Loose, self-hardened and drum-granulated ashes (wood and peat ashes) were used and applied (5000–6500kgha−1) either in winter on snow or in summer on bare ground. Water samples from the runoff were taken over a 10–11-year period following the applications. After 10–11years from the treatments, the concentrations of S, K, Na, Cl−, and Mg in the runoff water were still higher at the wood ash treatments compared to the controls. Leaching of elements from peat ash was lower than from wood ash due to the lower content of elements. We estimated that 15–52% of the added S and 2–28% of the added K were leached from the wood and peat ashes during the study period. Leaching of S was the highest after the winter application and higher from the Sphagnum than from the Carex peat dominated catchments. The leaching of K was the highest after the summer application and was the lowest from the catchments having the highest tree stock. No increased leaching of P, N, dissolved organic carbon or heavy metals was detected.