Finnish Peatland Research Articles

Potential pre-industrial-like new particle formation induced by pure biogenic organic vapors in Finnish peatland.

Pure biogenic new particle formation (NPF) induced by highly oxygenated organic molecules (HOMs) could be an important mechanism for pre-industrial aerosol formation. However, it has not been unambiguously confirmed in the ambient due to the scarcity of truly pristine continental locations in the present-day atmosphere or the lack of chemical characterization of NPF precursors. Here, we report ambient observations of pure biogenic HOM-driven NPF over a peatland in southern Finland. Meteorological decoupling processes formed an "air pocket" (i.e., a very shallow surface layer) at night and favored NPF initiated entirely by biogenic HOM from this peatland, whose atmospheric environment closely resembles that of the pre-industrial era. Our study sheds light on pre-industrial aerosol formation, which represents the baseline for estimating the impact of present and future aerosol on climate, as well as on future NPF, the features of which may revert toward pre-industrial-like conditions due to air pollution mitigation.

The ongoing lateral expansion of peatlands in Finland.

Peatlands are the most dense terrestrial carbon stock and since the last glacial epoch northern peatlands have accumulated between 400 and 1000 Gt of carbon. Although the horizontal development history of the peatlands during the Holocene has been previously researched, these studies have overlooked the current peatland margins. This has led to a long-standing view that the lateral expansion of the peatlands has halted or significantly slowed down. However, no concentrated effort focusing on the recent development of the peatland margins has been conducted. To fulfil this knowledge gap, we studied the development of peatland margins in five Finnish peatlands. In addition, we studied the effect of peatland subsoil characteristics and past forest fires on the peatland expansion. We sampled 15 transects with a total of 47 peat cores utilizing 14 C radiocarbon dating on the basal layers of these peat cores. Our results show that the Northern peatlands are still expanding with four of our study sites having recent, post-1950's basal ages in the peatland margins. In addition, the rate of peatland lateral expansion has increased during the last 1500 years in our study sites, challenging the current knowledge of the recent peatland expansion dynamics. We recorded lateral expansion rates of 0.1-6.4 cm/year from the sites studied. The rate of lateral expansion was restricted by local characteristics, especially the steepness of subsoil (p = .0108). Forest fires likely played an important role as the trigger for lateral expansion in southern study sites with large number of charcoal found at the basal layer of the peat cores. Depending on the scope of this recent lateral expansion across the vast northern peatlands, the effect on the carbon balance could be significant and should be taken into account when estimating the development of carbon pools in these crucial ecosystems.

Sidestream materials show potential as top-dressed soil improvers for peatland forests.

The effects of top-dressing of several industrial and farming sidestream materials on the growth of downy birch (Betula pubescens Ehrh.) and Scots pine (Pinus sylvestris L.) seedlings in natural sphagnum peat soil were evaluated. Wood fly ash, industrial filter cake waste, mine tailings sand (quartz feldspar from lithium orebody), and digestate and liquid reject of cow manure from a biogas plant were studied for their physical and chemical properties, as well as for their effects as soil ameliorants on seedling growth during one growing period in a greenhouse. Each material was top-dressed on unfertilised peat in pots in quantities that corresponded to the amounts of ash used in Finnish peatland forest fertilisation (2-6tha-1). During growing, the pH of percolate water from the growing pots was below 4, and in the treatments with filter cake even below 3. However, no clear impairment of seedling growth due to acidity was observed. In all treatments, birch and pine seedlings grew at least as well as in the unfertilised peat (control treatment). Growth was strongest in the peat top-dressed with additives originating from cow manure, in which the high N and P contents promoted growth so much that foliar N was found to be diluted with respect to a high P content in the birch seedlings. No harmful concentrations of heavy metal residues were observed from the materials used. Overall, the results suggest that all the used sidestream materials show potential as soil improvers on forested peatlands.

Monitoring peatland water table depth with optical and radar satellite imagery

Peatland water table depth (WTD) and wetness have widely been monitored with optical and synthetic aperture radar (SAR) remote sensing but there is a lack of studies that have used multi-sensor data, i.e., combination of optical and SAR data. We assessed how well WTD can be monitored with remote sensing data, whether multi-sensor approach boosts explanatory capacity and whether there are differences in regression performance between data and peatland types. Our data consisted of continuous multiannual WTD data from altogether 50 restored and undrained Finnish peatlands, and optical (Landsat 5–8, Sentinel-2) and Sentinel-1 C-band SAR data processed in Google Earth Engine. We calculated random forest regressions with dependent variable being WTD and independent variables consisting of 21 optical and 10 SAR metrics. The average regression performance was moderate in multi-sensor models (R 2 43.1%, nRMSE 19.8%), almost as high in optical models (R 2 42.4%, nRMSE 19.9%) but considerably lower in C-band SAR models (R 2 21.8%, nRMSE 23.4%) trained separately for each site. When the models included data from several sites but were trained separately for six habitat type and management option combinations, the average R 2 was 40.6% for the multi-sensor models, 36.6% for optical models and 33.7% for C-band SAR models. There was considerable site-specific variation in the model performance (R 2 −3.3–88.8% in the multi-sensor models ran separately for each site) and whether multi-sensor, optical or C-band SAR model performed best. The average regression performance was higher for undrained than for restored peatlands, and higher for open and sparsely treed than for densely treed peatlands. The most important variables included SWIR-based optical metrics and VV SAR backscatter. Our results suggest that optical data works usually better than does C-band SAR data in peatland WTD monitoring and multi-sensor approach increases explanatory capacity moderately little.

Potential of high pH and reduced sulfur for arsenic mobilization – Insights from a Finnish peatland treating mining waste water

Peatlands, used for purification of mining waste waters, have shown efficient solid-phase sequestration of contaminants such as arsenic (As). However, contaminant re-mobilization may occur related to management changes or chemical alteration of original peatland conditions. For a treatment peatland in Finnish Lapland, we here confirm efficient As retention in near-surface peat layers close to the mining waste water inflow, likely due to binding to FeIII-phases. Seven years into operation of the treatment peatland, there appears to be further retention potential, as large areas downstream still had solid-phase As concentrations at background levels. However, via depth-resolved pore water analysis we observed a hotspot 170 m from the inflow at 10–50 cm depth, where As pore water concentrations exceeded input concentrations by a factor of 20, indicating substantial As re-mobilization. At the same spot, a peak of reduced sulfur (S) species was found. Arsenic species detected were arsenite and up to 26% methylated oxyarsenates, 15% methylated and 7.9% inorganic thioarsenates. We postulate that As mobilization is a result of short-term re-equilibration to a changed inflow chemistry after installation of a process water treatment plant and a long-term consequence of changing pore water pH from acidic to near-neutral, releasing reduced S and As. We infer that the co-occurrence of reduced S and As leads to formation of methylated and/or thiolated As species with known low sorption affinity, thereby further enhancing As mobility. Laboratory incubation studies with two peat cores confirmed a high S-induced As mobilization potential, especially when As-Fe-rich, oxic surface layers were incubated anoxically at near-neutral pH. Highest risk of As re-mobilization from this treatment peatland is expected in a scenario in which mining waste water inflow has stopped but the peatland remains flooded, and near-surface layers transition from oxic to anoxic conditions.

The influence of anthropogenic land use on Finnish peatland area and carbon stores 1950–2015

The influence of anthropogenic land use on Finnish peatland area and carbon stores 1950–2015

Discursive Struggle and Agency—Updating the Finnish Peatland Conservation Network

This paper explores the process of updating the peatland conservation network in Finland—the Supplemental Mire Conservation Programme, which was drafted from 2012 to 2015. This study employs discursive agency approach (DAA), to reveal how agents actively seek to gain legitimate speaker positions and influence policy outcomes as they rely on existing discourses. It also studies the role of discourse in the context of Finnish peatland conservation policy and evaluates the role of agents in the discursive process and how they influenced the outcome. The empirical data consists of expert interviews, newspaper articles and policy documents. The results indicate that the discourses of ‘maintenance of biodiversity’, ‘regulatory program’, ‘voluntary conservation’ and ‘participatory approach’ influence the peatland conservation policy. Additionally, discursive agency is achieved through hegemonic discourse and a consensus seeking argumentation strategy that rely on keywords, such voluntary and sustainability.

The case of conflicting Finnish peatland management – Skewed representation of nature, participation and policy instruments

Peatlands that are close to a natural state are rich in biodiversity and are significant carbon storages. Simultaneously, peat resources are of interest to industry, which leads to competing interests and tensions regarding the use and management of peatlands. In this case study, we studied knowledge–management interactions through the development of participation and the resulting representation of nature (how nature was described), as well as the proposed and implemented conservation policy instruments. We focused on the years 2009–2015, when peatland management was intensively debated in Finland. We did an interpretative policy analysis using policy documents (Peatland Strategy; Government Resolution; Proposal for Conservation Programme) and environmental legislation as central data. Our results show how the representation of nature reflected the purpose of the documents and consensus of participants' values. The representation of nature changed from skewed use of ecosystem services to detailed ecological knowledge. However, simultaneously, political power changed and the planned supplementation programme for peatland conservation was not implemented. The Environment Protection Act was reformulated so that it prohibited the use of the most valuable peatlands. Landowners did not have the chance to fully participate in the policy process. Overall, the conservation policy instruments changed to emphasize voluntariness but without an adequate budget to ensure sufficient conservation.

Effective arguments for ecosystem services in biodiversity conservation – A case study on Finnish peatland conservation

Political and socially constructed arguments about values and benefits originating from ecosystem services (ES) may improve the effectiveness of biodiversity conservation. In this article we show how effective biodiversity conservation is dependent on stakeholders’ rhetorical skills and their ability to introduce persuasive arguments for the target audience. We present a case study of a lengthy conflict to protect a mire area located in Eastern Finland. We follow locally constructed arguments and analyse their effectiveness with different audiences. Research data consist of interviews, newspaper articles and legal documents. Employing content analysis, we study the ES identified by different stakeholders and analyse the effectiveness and sources of arguments presented on behalf of those services. We differentiate between legal and political effectiveness as many ES arguments were effective in sustaining the prolonged conflict locally but ineffective in administrative courts. Legislation and scientific evidence are identified as the main sources for an effective argument in legal proceedings. This case is an example of how local residents require support from scientists in order to formulate effective arguments for legal audiences. Valid arguments for legal institutions are based on the protection of individual species or biotypes whereas political processes are more responsive to local ES valuations.

Reconstruction of Holocene carbon dynamics in a large boreal peatland complex, southern Finland

Holocene peatland development and associated carbon (C) dynamics were reconstructed for a southern boreal Finnish peatland complex with fen and bog areas. In order to assess the role of local factors and long-term allogenic climate forcing in peatland development patterns, we studied a total of 18 peat cores and reconstructed vertical peat growth and lateral peat area expansion rates, the C accumulation rate (CAR), past vegetation composition and past methane (CH4) fluxes. We combined fossil plant data with measured contemporary CH4 flux – vegetation relationship data to reconstruct CH4 fluxes over time. When these reconstructions were added to the CAR estimations, a more complete picture of Holocene-scale C dynamics was achieved. Basal peat ages showed that expansion of the peat area was rapid between 11,000 and 8000 cal. BP, but decreased during the dry mid-Holocene and is probably currently limited by basal topography. A similar pattern was observed for peat growth and CAR in the fen core, whereas in the bog core CAR increased after ombrotrophication, i.e. after 4400 cal. BP. The effect of fire on vegetation and CAR was more conspicuous at the bog site than at the fen site. The CH4 flux reconstructions showed that during the Holocene CH4 emissions at the fen site decreased from 19 ± 15 to 16 ± 8 g CH4 m−2 yr−1 and at the bog site from 20 ± 15 to 14 ± 8 g CH4 m−2 yr−1. Our results suggest that a combination of changing climate, fire events and local conditions have modified the autogenic peatland development and C dynamics.

Plant macrofossil and biomarker evidence of fen–bog transition and associated changes in vegetation in two Finnish peatlands

Past vegetation assemblages, preserved in peat layers, are one of the key proxies when reconstructing historical peatland dynamics. Northern peatlands can be divided into two main types: fens and bogs. Compared with bog peat, the fen peat is usually more decomposed because of different eco-hydrological conditions and effective humification processes. A high level of decomposition hampers reliable identification of plant remains and constrains palaeoecological approaches. Biogeochemical studies on bog plants and bog peat have shown that plant group–specific biomarkers can be applied to identify fossil plants or plant groups from peat, given the identification of plant group–specific markers in living fen plants. In this study, we applied plant macrofossil, biomarkers and multivariate statistical analyses to two mid-boreal peat sequences to investigate whether biomarkers can be applied to distinguish fen and bog environments and whether plant-specific biomarkers can be identified from fen peat. Macrofossil analyses clearly separate dry bog hummocks, moist lawns and wet fen habitats apart. Corresponding division emerged when the biomarker data were combined with the macrofossil data. Moreover, we succeeded to separate bog and fen habitats apart by the changes in n-alkane and the n-alkane ratio distributions along the cores. The fen–bog transition zone was indicated by high sterol and triterpenoid concentrations and changes in degradation measures. However, it remains a challenging task to attain species-level information of past plant assemblages from highly humified fen peat layers based on biomarkers only.

Age and source of different forms of carbon released from boreal peatland streams during spring snowmelt in E. Finland

Isotopic data are increasingly being used to quantify and understand the processes that control the release of carbon (C) from northern peatlands. We used δ13C and 14C measurements to investigate the source and age of different forms of aquatic C (DOC, POC and evasion CO2) released from 2 contrasting (undrained v drained) forested peatland catchments at the end of the winter snowmelt period in boreal E Finland. The δ13CVPDB values of DOC (range −28.3 to −28.8 ‰) were generally more 13C depleted than evasion CO2 (range −22.7 to −31.5 ‰) and showed no clear differences between the pre-flood, flood and post-flood periods. Both forms of C had evidence of bomb-14C (i.e. >100%modern), indicating that they contained substantial quantities of C fixed since the mid AD 1950s. However, DOC was 14C enriched compared to evasion CO2, with 14C concentrations suggesting that, on average, DOC-C was ~5–6 years younger than evasion CO2–C, with the most recently fixed C being released when temperatures were highest. POC was significantly depleted in 14C with conventional (uncalibrated) radiocarbon ages of 805–1135 BP. In contrast to other studies, the isotopic compositions of DOC and evasion CO2 were very similar, suggesting a predominantly single and consistent C source (decomposition of soil organic matter; SOM) during the snowmelt period. Whilst we found no evidence to suggest that old (pre-bomb) C was being released at the end of the winter period, the drained site was associated with more 14C depleted and 13C enriched evasion CO2, suggesting a closer link to the atmospheric CO2 pool. Our isotopic data suggest that the various forms of C released to the aquatic system from these forested Finnish peatlands are closely related, largely unaffected by drainage and (at least in the case of evasion CO2 and DOC) indicate strong connectivity between C cycling in the soil–plant–water system.

Stream water hydrochemistry as an indicator of carbon flow paths in Finnish peatland catchments during a spring snowmelt event

Extreme hydrological events are known to contribute significantly to total annual carbon export, the largest of which in Arctic and boreal catchments is spring snowmelt. Whilst previous work has quantified the export of carbon during snowmelt, the source of the carbon remains unclear. Here we use cation hydrochemistry to trace the primary flowpaths which govern the export of carbon during the snowmelt period; specifically we aim to examine the importance of snowpack meltwater to catchment carbon export. The study was carried out in two forested peatland (drained and undrained) catchments in Eastern Finland. Both catchments were characterised by base-poor stream water chemistry, with cation concentrations generally decreasing in response to increasing discharge. Streamflow during the snowmelt period was best described as a mixture of three sources: pre-event water, snowpack meltwater and a third dilute component we attribute to the upper snow layer which was chemically similar to recent precipitation. Over the study period, pre-event water contributed 32% and 43% of the total stream runoff in Välipuro (undrained) and Suopuro (drained), respectively. The results also suggest a greater near-surface throughflow component in Suopuro, the drained catchment, prior to snowmelt. CO 2 and DOC concentrations correlated positively with cation concentrations in both catchments indicating a common, peat/groundwater flowpath. CH 4 concentrations were significantly higher in the drained catchment and appeared to be transported in near-surface throughflow. Meltwater from the snowpack represented an important source of stream water CO 2 in both catchments, contributing up to 49% of total downstream CO 2 export during the study period. We conclude that the snowpack represents a potentially important, and often overlooked, transient carbon store in boreal snow-covered catchments.

Land-use scenarios for Finnish cut-over peatlands - based on the mineral subsoil characteristics

In Finland, peat harvesting sites are exploited down almost to the mineral soil and the properties of mineral subsoil have considerable influence on the suitability for the various afteruse forms. Chemical and physical features of the mineral subsoil must be studied when after-use is planned, to ensure no harmful effects follow. Research on mineral subsoils was carried out on Finnish peat production sites in 1997 – 1998 and 9800 hectares of peat production areas slowly getting exhausted were studied. The cutover area clearly suitable for forestation covered 57 % of the study area. The area well suitable for agriculture or energy crop growing covered 26 – 42 % of the study – depending if boulder-poor tills were included or excluded. Even larger areas might be possible for agriculture if for example remaining peat layer was used for compensating physical features of the mineral subsoil. Approximately 11 % was recommended for mire regeneration because of sensitive bottom soils, but much larger areas were possible for mire regeneration. In 9 % of all cases fine miner al subsoils were on pool-forming locations and would this way offer sites best suitable for mire regeneration or even bird sanctuaries. Both EC and pH of the mineral subsoils were related to the presence of sulphur. The concentrations of Ca, Mg and K followed the finematerial percentage. Based on this study minimum analysis recommended was for pH, sulphur content and fine material (< 0.06 mm) percentage. Other relevant elements were calcium, magnesium and potassium. Different land-use scenarios were created for areas in after-use, released from peat production and in peat production (2004). These scenarios were based on the mineral subsoil suitability for different after-use forms. In these scenarios the total area annual carbon fixation values varied between 0.096 and 0.152 million t C a -1 , when carbon emissions were not included.

Carbon balance and radiative forcing of Finnish peatlands 1900–2100 – the impact of forestry drainage

AbstractNatural peatlands accumulate carbon (C) and nitrogen (N). They affect the global climate by binding carbon dioxide (CO2) and releasing methane (CH4) to the atmosphere; in contrast fluxes of nitrous oxide (N2O) in natural peatlands are insignificant. Changes in drainage associated with forestry alter these greenhouse gas (GHG) fluxes and thus the radiative forcing (RF) of peatlands. In this paper, changes in peat and tree stand C stores, GHG fluxes and the consequent RF of Finnish undisturbed and forestry‐drained peatlands are estimated for 1900–2100. The C store in peat is estimated at 5.5 Pg in 1950. The rate of C sequestration into peat has increased from 2.2 Tg a‐‐1 in 1900, when all peatlands were undrained, to 3.6 Tg a‐‐1 at present, when c. 60% of peatlands have been drained for forestry. The C store in tree stands has increased from 60 to 170 Tg during the 20th century. Methane emissions have decreased from an estimated 1.0–0.5 Tg CH4‐‐C a‐‐1, while those of N2O have increased from 0.0003 to 0.005 Tg N2O‐‐N a‐‐1. The altered exchange rates of GHG gases since 1900 have decreased the RF of peatlands in Finland by about 3 mW m‐‐2 from the predrainage situation. This result contradicts the common hypothesis that drainage results in increased C emissions and therefore increased RF of peatlands. The negative radiative forcing due to drainage is caused by increases in CO2 sequestration in peat (‐‐0.5 mW m‐‐2), tree stands and wood products (‐‐0.8 mW m‐‐2), decreases in CH4 emissions from peat to the atmosphere (‐‐1.6 mW m‐‐2), and only a small increase in N2O emissions (+0.1 mW m‐‐2). Although the calculations presented include many uncertainties, the above results are considered qualitatively reliable and may be expected to be valid also for Scandinavian countries and Russia, where most forestry‐drained peatlands occur outside Finland.

Winter CO2, CH4 and N2O fluxes on some natural and drained boreal peatlands

CO2 and CH4 fluxes during the winter were measured at natural and drained bog and fen sites in eastern Finland using both the closed chamber method and calculations of gas diffusion along a concentration gradient through the snowpack. The snow diffusion results were compared with those obtained by chamber, but the winter flux estimates were derived from chamber data only. CH4 emissions from a poor bog were lower than those from an oligotrophic fen, while both CO2 and CH4 fluxes were higher in the Carex rostrata-occupied marginal (lagg) area of the fen than in the slightly less fertile centre. Average estimated winter CO2-C losses from virgin and drained forested peatlands were 41 and 68 g CO2-C m- 2, respectively, accounting for 23 and 21% of the annual total CO2 release from the peat. The mean release of CH4-C was 1.0 g in natural bogs and 3.4 g m-2 in fens, giving rise to winter emissions averaging to 22% of the annual emission from the bogs and 10% of that from the fens. These wintertime carbon gas losses in Finnish natural peatlands were even greater than reported average long-term annual C accumulation values (less than 25 g C m-2). The narrow range of 10–30% of the proportion of winter CO2 and CH4 emissions from annual emissions found in Finnish peatlands suggest that a wider generalization in the boreal zone is possible. Drained forested bogs emitted 0.3 g CH4-C m-2 on the average, while the effectively drained fens consumed an average of 0.01 g CH4-C m- 2. Reason for the low CH4 efflux or net oxidation in drained peatlands probably lies in low substrate supply and thus low CH4 production in the anoxic deep peat layers. N2O release from a fertilized grassland site in November–May was 0.7 g N2O m-2, accounting for 38% of the total annual emission, while a forested bog released none and two efficiently drained forested fens 0.09 (28% of annual release) and 0.04 g N2O m- 2 (27%) during the winter, respectively.

Methane fluxes on boreal peatlands of different fertility and the effect of long‐term experimental lowering of the water table on flux rates

Methane (CH4) fluxes were measured at 17 peatland sites with different nutritional and hydrological characteristics in the southern and middle boreal zones in Finland by a static chamber technique. Many of the natural peatlands also had counterparts drained for forestry 30–50 years ago. The mean emissions from May to September were 8.0 g CH4 m−2 for natural ombrogenous bogs and 19.0 g CH4 m−2 for natural minerogenous fens thus being higher than the 2 g CH4 m−2 yr−1 estimated for the Canadian peatlands. Change in the mean water table level had greater effect on CH4 fluxes on natural fens than on natural bogs. The mean CH4 emissions on drained bogs and fens were 3.9 g CH4 m−2 and 0.3 g CH4m−2, respectively. Some drained fens even had CH4 uptake from the atmosphere. The change in the mean water table had the lowest effect on CH4 fluxes on drained peatlands. The CH4 fluxes on peatlands (natural fens and bogs and drained peatlands) are associated with peat aeration, nutrient level, vegetation cover, peat compaction, peat temperature, and finally with microbial processes responsible for the net release of CH4. We could explain 67% of the variation in mean CH4 fluxes on Finnish peatlands by measuring the mean water table, peat bulk density, and peat pH. The present results can be used to predict the possible changes in CH4 emissions on peatlands if the climate is drying in north. For example, lowering of the present water table by 10 cm would induce a 70% reduction in the CH4 emissions from fens and a 45% reduction from bogs.

Accumulation rates of carbon in mires in Finland and implications for climate change

Stratigraphical analyses based on 1028 dated Holocene peat cores were used to estimate the rate of carbon accumulation in Finnish peatlands. Results were compared with data from other Boreal areas. The basal age of peat columns was found to be the best predictor of carbon accumulation and a significant correlation between depth and age of peat was evident. When normalized for the mean depth of peatlands in Finland ( c. 1.5 m), the average long-term carbon accumulation was 26.1 g C m-2 yr-1. In individual cores the values ranged from 2.8 to 88.6 g (average 22.5 ± 11.6 g) being much higher in bogs than in fens and almost double in southern mires as compared with those in the northern Boreal zone. The modelled rate of actual carbon accumulation is about 2/3 of that above. Boreal mires are actual sinks of carbon for thousands of years ahead in the present climate. The predicted greenhouse warming may shift the present Sphagnum mires northward and the net effect may be to restrain the radiative forcing. Poorly known 3D mass accumulation in mires and unpredictable functioning of northern mire ecosystems to climatic changes (for example via increased mire fires) complicate this interpretation.

Composition of long-chain fatty compounds and sterols of four milled peat samples from Finnish peatlands

Four milled peat samples from three Finnish peatlands were studied in terms of their extract content and composition of fatty compounds and sterols using capillary g.c.-m.s. The extract yields obtained by CH 2Cl 2-acetone (9:1 v/v) ranged from 49 to 180 mg g −1 of dry peat. The wax content of peat extracts varied between 43 and 55 wt %. The acidic part of extracts contained mainly long-chain fatty acids and ω-hydroxy acids with some α,ω-alkanedioic acids. The neutral extractives included predominantly primary alkanols with smaller amounts of n-alkanes and sterols. The extracts of all four peat samples were qualitatively similar but the milled peat Al with high heat value (27.1 MJ kg −1) differed from the other peats in extract content and composition. The peat B with enhanced self-heating ability resembled the ordinary milled peats A2 and C in peat technological characteristics and extractive composition. Accordingly, the self-heating ability of milled peat in stockpiles does not correlate directly to the distribution pattern of long-chain fatty compounds and sterols.