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Fort McMurray and the Athabasca oil sands region (AOSR) experienced major wildfires in 2016, but the impact of these on regional deposition of polycyclic aromatic hydrocarbons (PAHs) and trace elements has not been reported nor compared to industrial sources of these pollutants in the region. Living moss (Sphagnum fuscum) was collected in triplicate from five ombrotrophic bogs in the AOSR after the wildfires, and analyzed for PAHs and trace elements. These post-wildfire data were compared to data from previous years at the same sites, and also to remote reference bogs in Alberta and Ontario. Elevated post-wildfire concentrations and flux of naphthalene and fluorene were observed at all five bogs in the AOSR, but no consistent trend was evident for higher molecular weight PAHs or the sum of priority PAHs (∑13PAH). Trace elements at most AOSR bogs were not elevated post-wildfire, except at one bog in the burned area (MIL), but even here the elements that were increased (1.7–5.6 × ) were likely of bitumen-origin (i.e., V, Ni, Se, Mo and Re). Significant post-wildfire correlations between PAHs and most trace elements suggested a common source, and few significant correlations were observed with retene, suggesting that wildfires were not the dominant source of most contaminants detected. Mass balance receptor models were used to apportion sources, indicating that the major sources of trace elements among five AOSR bogs post-wildfire were oil sands ore (mean 42%), haul road dust (17%), and petcoke (11%), whereas wildfire was always a minor source (3–4%). For PAHs at the most contaminated site (MIL), delayed petcoke (27%) and wildfire (25%) were the major sources, but the contribution of wildfire to PAHs at other sites was less or not discernable. Impacts of the 2016 wildfires on regional atmospheric deposition of major pollutants was less than from ongoing deposition of anthropogenic dust from oil sands activities.

Boreal peatlands, of which Sphagnum bogs are one of the main types, play essential roles in the terrestrial soil carbon pool. Vegetation phenology is a sensitive indicator that reveals the underlying processes as well as responses to climate change, while currently there remain knowledge gaps in exploring and monitoring the longterm bog vegetation phenology due to insufficient remote sensing application experiences. In this study, we investigated three remotely sensed vegetation phenological parameters, the start of growing season (SOS), the end of growing season (EOS), and the length of growing season (LOS) in two bogs located in norther China by using double-logistic reconstructed MOD13Q1-EVI from 2001 to 2018, which were evaluated by the flux phenology. Also combing with meteorological data to detect interactions between vegetation phenology and climate change. The results showed that remotely sensed EOS had 8-day time lags with flux phenological date, while that outperformed SOS. Bog vegetation generally with a life pattern of SOS at the 108th day of year (doy) and EOS at the 328th doy, though the life cycle of individual vegetation groups varies among different vegetation communities. There was no significant delayed (or extended) trend in each phenological features in bogs. Precipitation and minimum temperature (monthly and annual) were the driving forces for bog vegetation growth (R2 0.9, P < 0.01), and other features presented weaker correlations. Overall, this study determined the remote sensing phenology and climate drivers in two Chinese bogs, we suggested that vegetation phenology alternation should be concerned when carry on ecological processes and carbon dynamics researches in peatlands.

This study was supported by the projects CGL2013-47038-R and CGL2017-85415-R funded by Ministerio de Economia y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER; Seneca Project 20788/PI/18; Junta de Andalucia FEDER Project B-RNM-144-UGR18, Proyectos I + D + i del Programa Operativo FEDER 2018 and the research group RNM-190 (Junta de Andalucia). Alejandro Lopez Aviles acknowledges the PhD funding, BES-2018-084293, provide by Ministerio de Economia y Competitividad of the Spanish Government. Antonio Garcia-Alix acknowledges the Ramon y Cajal fellowship, RYC-2015-18966, provided by the Ministerio de Economia y Competitividad of the Spanish Government. R. Scott Anderson acknowledges travel support from Northern Arizona University., Several organic and inorganic geochemical analyses have been carried out in the sedimentary record of the Borreguil de los Lavaderos de la Reina (BdlR-03), an alpine peat bog located on the north face of the Sierra Nevada (southern Iberian Peninsula). This study permitted a high-resolution reconstruction of paleoenvironmental evolution for the last similar to 2700 cal yr BP in the highest mountain range of southern Iberian Peninsula. An overall trend towards a climatic aridification and a reduction of aquatic environments is observed in this record. Insolation and long-term positive North Atlantic Oscillation trends were the most important factors controlling this aridification, forcing regional and local environmental changes. Four phases are differentiated within the paleoenvironmental evolution of BdlR-03: (1) a pre-bog environment from 2700 to 2600 cal yr BP with important siliciclastic sedimentation and low organic content; (2) a bog environment with important presence of terrestrial vascular plant, water availability and maximum humid conditions between similar to 2600 and similar to 1870 cal yr BP, coinciding with the Iberian-Roman Humid Period; (3) a subsequent drier bog environment, between similar to 1870 and similar to 300 cal yr BP during the Dark Ages, the Medieval Climate Anomaly and the first stages of the Little Ice Age, characterized by lower productivity that affected the development of terrestrial vascular plants and aquatic environments; and (4) a wetland environment with an increase of aquatic algae, development of ephemeral pools and unstable climate conditions between similar to 300 cal yr BP and the present, coinciding with the final stages of the Little Ice Age and the Modern Global Warming. This recent environmental pattern, which is opposite to the general aridification trend in the western Mediterranean, is likely explained by the gradual melting of the perennial ice and/or snow packs at higher elevations in the last centuries. Aeolian inputs would have continuously contributed nutrients to these nutrient-impoverished alpine environments. High dust inputs are especially noticed during the last similar to 200 years, which can be explained by human-induced enhanced aridification and the development of the commercial agriculture in some North African regions. In addition, the environmental signal in the last century seems to be significantly affected by human activities., Ministerio de Economia y Competitividad of Spain CGL2013-47038-R CGL2017-85415-R, European Commission, Junta de Andalucia FEDER Project B-RNM-144-UGR18, Ministerio de Economia y Competitividad of the Spanish Government BES-2018-084293, Ramon y Cajal fellowship by the Ministerio de Economia y Competitividad of the Spanish Government RYC-2015-18966, Fundacion Seneca 20788/PI/18, Junta de Andalucia, Proyectos I + D + i del Programa Operativo FEDER 2018

The lichen Cladonia portentosa is generally considered to be sensitive to increased environmental nitrogen (N) deposition. However, the presence of this lichen in impacted environments suggests that it can cope with prolonged exposure to high N availability. To test the tolerance of this species to N, photosynthetic parameters, carbon and N concentrations and isotopic signature, chitin concentration, surface pH and extracellular enzymatic activity were measured in samples exposed for 11 years to different N doses and forms at the Whim bog N manipulation experimental site (United Kingdom). The results showed that C. portentosa is tolerant to long-term exposure to wet N deposition, maintaining its functionality with almost unaltered physiological parameters. The comparison of the proteome of short- and long-term exposed samples showed similar changes in protein expression suggesting that mechanisms to cope with N are not dependent on the exposure time even after more than a decade. Since empirical N Critical Loads are based on the response of sensitive components of the ecosystem, like C. portentosa, its capacity to cope with short- and long-term exposure to N needs to be recognized and taken into account when setting them, likewise, the significance of the form of N., Investigador - Fundação para Ciência e Tecnologia (FCT) contract and the FCT projects IF/00964/2013 and UID/BIA/00329/2013 (2015–2018).

Kvalsund in the Herøy archipelago, Møre og Romsdal County, provides a sheltered harbour in a high-risk seascape along the west coast of Norway: the peninsula Stadlandet is considered the most dangerous part of the seaway between central and south Norway. At least three separate offerings were identified in a bog along the sound, one of which was excavated in the 1920s. The excavation uncovered the remains of two vessels: an ordinary boat and a ship, which were both difficult to date at the time of discovery. The site is of significant interest for two reasons. First, from a technological perspective: the ship is technologically regarded as preceding the Oseberg ship type (c. AD 820), but later than the Nydam ship (AD 310–320). The date of the ship type is consequently important, as part of the evolution of the clinker built ship of the Viking Age. Secondly, from a ritual perspective: the site was interpreted in the 1920s as an offering, and as comparable to Early Iron Age bog offerings in Denmark (a category which the Nydam ship belongs to). In 1980, the Kvalsund find was radiocarbon dated, placing the find in the range of the 7th to 8th centuries AD. This indicates that the Kvalsund offerings were later than the Early Iron Age bog offerings in Denmark. Since the 1980s, most ships from the Late Iron Age in Norway (i.e. c. AD 560–1050) are provided with a more accurate date by dendrochronology, but the Kvalsud vessels have lacked dendrochronological dates. This article presents the site, the finds, and a new dendrochronological date for the Kvalsud vessels. This is an open access article distributed under the terms of the Creative Commons CC-BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Wetlands provide habitat for a wide variety of plant and animal species and contribute significantly to overall biodiversity in Ireland. Despite these known ecosystem services, the total wetland area in Ireland has reduced significantly over the past few decades leading to an ongoing need to protect such environments. The EU Habitats Directive (92/43/EEC) has recognised several wetlands types as “priority” habitats. This study concentrates on a subset of the priority habitats focussing on some groundwater dependent terrestrial ecosystems, (in particular calcareous fens and turloughs), as well as raised bogs. Monitoring these sites across the country by field visits is resource-intensive. Therefore, this study has evaluated remote sensing as a potentially cost-effective tool for monitoring the ecological health of the wetlands. Identification and presence of certain vegetation communities can indicate the condition of the wetland, which can be used for monitoring, for example, activities causing degradation or the progress of restoration attempts. The ecological composition of the wetlands has been analysed using open-source Sentinel-2 data. 10 bands of Sentinel-2 Level-2 data and 3 indices, Normalised Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and Normalised Difference Water Index (NDWI) were used to create vegetation maps of each wetland using Bagged Tree (BT) ensemble classifier and graph cut segmentation also known as MAP (maximum a posteriori) estimation. The proposed methodology has been validated on five raised bogs, five turloughs, and three fens at different times during 2017 and 2018 from which three case studies are presented. An overall classification accuracy up to 87% depending on the size of the vegetation community within each wetland has been achieved which suggests that the proposed method is appropriate for wetland health monitoring.

There has been an increasing interest in enhancing freshwater aquaculture processes without hindering the progress of the Water Framework Directive. Bord Iascaigh Mhara (Ireland’s national seafood development organisation), undertook a feasibility study to assess the potential use of peatlands (bogs) for sustainable aquaculture diversification. AquaMona, a new concept in integrated multitrophic aquaculture (IMTA), uses cutaway bogs to farm rainbow trout and Eurasian perch with associated organic status that is powered by wind energy and utilizes algae and duckweed to treat rearing water. Approximately 5% of Ireland comprises bogs that support natural ecosystems where there is a pressing need to develop alternative innovation to that of burning peat in order to reduce Ireland’s carbon emissions. This constitutes the first study to evaluate water quality from this new IMTA where intake and terminal holding tank samples were evaluated from May to August 2019. Physicochemical parameters (temperature, pH, nitrogen, phosphorus, oxygen, suspended solids, hardness and alkalinity), and ecotoxicological bioassays (Pseudokirchneriella subcapitata and Daphnia pulex), were used to investigate the potential effects that introducing aquaculture processes may have on peatlands. Nitrite (p

Drained peatlands are hotspots of carbon dioxide (CO2) emissions from agricultural soils. As a consequence of both drainage-induced mineralisation and anthropogenic mixing with mineral soils, large areas of former peatlands under agricultural use underwent a secondary transformation of the peat (e.g. formation of aggregates). These soils show contents of soil organic carbon (SOC) at the boundary between mineral and organic soils. However, the carbon (C) dynamics of such soils have rarely been studied so far. The aim of the present study was to evaluate the vulnerability of soil organic matter (SOM) to decomposition over the whole range of peat-derived soils under agriculture including very carbon rich mineral soils (76–526 g kg−1 SOC). A total of 62 soil samples covering a broad range of soil and site characteristics were selected from the sample set of the German Agricultural Soil Inventory. Potential CO2 production was measured by aerobic incubation. Fen and bog peat samples were grouped into disturbance classes according to their soil properties. Specific basal respiration rates (SBR), i.e. CO2 fluxes per unit SOC, showed the highest values for the most disturbed samples for both fen peat (13.9 ± 6.0 μg CO2-C g SOC−1 h−1) and bog peat (10.9 ± 4.7 μg CO2-C g SOC−1 h−1). Respiration rates of bog peat increased more strongly with an increasing degree of disturbance than those of fen peat. Perhaps counterintuitively, SOM vulnerability to decomposition thus increased with an increasing degree of disturbance and a decreasing SOC content, indicating positive feedback mechanisms as soon as peat soils are disturbed by drainage. Furthermore, the variability of the SBR increased drastically with increasing degree of disturbance. The turnover of SOM in less disturbed peat samples tended to be higher in samples with higher nitrogen (N) content, higher pH value and lower C:N ratio, while plant-available phosphorus was important for the mineralisation of more severely disturbed peat. However, clear correlations between a single soil property and SBR could not be identified. The high potential of CO2 emissions from organic soils with a low SOC content implies that mixing organic soil with mineral soil does not seem to be a promising option for mitigating greenhouse emissions.

Sphagnum fuscum was collected from twenty-five ombrotrophic (rain-fed) peat bogs surrounding open pit mines and upgrading facilities of Athabasca Bituminous Sands (ABS) in northern Alberta (AB) in order to assess the extent of atmospheric contamination by trace elements. As a control, this moss species was also collected at a bog near Utikuma (UTK) in an undeveloped part of AB and 264 km SW of the ABS region. For comparison, this moss was also collected in central AB, in the vicinity of the City of Edmonton which is approximately 500 km to the south of the ABS region, from the Wagner Wetland which is 22 km W of the City, from Seba Beach (ca. 90 km W) and from Elk Island National Park (ca. 45 km E). All of the moss samples were digested and trace elements concentrations determined using ICP-SMS at a commercial laboratory, with selected samples also analyzed using instrumental neutron activation analysis at the University of Alberta.The mosses from the ABS region yielded lower concentrations of Ag, As, Bi, Cd, Cu, Pb, Sb, Tl, and Zn compared to the moss from the Edmonton area. Concentrations of Ni and Mo in the mosses were comparable in these two regions, but V was more abundant in the ABS samples. Compared with the surface vegetation of eight peat cores collected in recent years from British Columbia, Ontario, Quebec and New Brunswick, the mean concentrations of Ag, As, Bi, Cd, Cu, Mo, Ni, Pb, Sb, Tl and Zn in the mosses from the ABS region are generally much lower. In fact, the concentrations of these trace elements in the samples from the ABS region are comparable to the corresponding values in forest moss from remote regions of central and northern Norway.Lithophile element concentrations (Ba, Be, Ga, Ge, Li, Sc, Th, Ti, Zr) explain most of the variation in trace metal concentrations in the moss samples. The mean concentrations of Th and Zr are greatest in the moss samples from the ABS region, reflecting dust inputs to the bogs from open pit mines, aggregate quarries, and gravel roads. Linear regressions of V, Ni, and Mo (elements enriched in bitumen) versus Sc (a conservative, lithophile element) show excellent correlations in the mosses from the ABS region, but this is true also of Ag, Pb, Sb and Tl: thus, most of the variation in the trace metal concentrations can be explained simply by the abundance of dust particles on the plants of this region. Unlike the moss samples from the ABS region and from UTK where Pb/Sc ratios resemble those of crustal rocks, the moss samples from the other regions studied yielded much greater Pb/Sc ratios implying significant anthropogenic Pb contributions at these other sites. Keywords: Sphagnum moss, Heavy metals, Athabasca Bituminous Sands, Vanadium, Nickel, Molybdenum

Plant succession triggered by drainage, which results in the expansion or invasion of vascular plants, has been reported from many peatlands. However, the effects of the vascular plant's expansion on evapotranspiration (ET), which is a key component of the water balance of ombrotophic bog, are still contradictory. To investigate the effects, ET was measured at a Sphagnum-dominated bog and an adjacent transition peatland dominated by Sasa, dwarf bamboo, in Hokkaido Island, northern Japan, using the eddy covariance technique during the four growing seasons from 2007 through 2010. Cumulative gap-filled ET during a snow-free period of 6.5 months was 362(2008) and 374 mm (2010) at the Sphagnum site and 300 (2008) and 372 mm (2010) at the Sasa site. In the mid-growing season (late June to mid-September) with the highest leaf area index (LAI) at the Sasa site, ET was 2.14 +/- 0.03 (mean 1 standard deviation of the four years) and 1.92 +/- 0.19 mm d(-1), respectively, at the Sphagnum and Sasa sites. ET was smaller at the Sasa site, except for 2010 with an unusual hot wet summer; mean air temperature and precipitation were higher than their 30-year normal values by 1.75 degrees C and 172 mm, respectively. At the Sphagnum site, ET was stable despite such interannual variation in meteorological conditions. However, ET increased significantly at the Sasa site in 2010 probably because of LAI increase due to the enhanced growth of Sasa plants. The ET increase at the Sasa site suggests that ET will increase at the Sasa-dominated area, if the future warming environment accompanies more precipitation. (C) 2016 Elsevier B.V. All rights reserved.

Globally, peatlands are under threat from a range of land use related factors that have a significant impact on the provision of ecosystem services, such as biodiversity and carbon (C) sequestration/storage. In Ireland, approximately 84% of raised bogs (a priority habitat listed in Annex I of the EU Habitats Directive) have been affected by peat extraction. While restoration implies the return of ecosystem services that were characteristic of the pre-disturbed ecosystem, achieving this goal is often a challenge in degraded peatlands as post-drainage conditions vary considerably between sites. Here, we present multi-year greenhouse gas (GHG) and vegetation dynamics data from two former raised bogs in Ireland that were drained and either industrially extracted (milled) or cut on the margins for domestic use and subsequently rewetted (with no further management). When upscaled to the ecosystem level, the rewetted nutrient poor domestic cutover peatland was a net sink of carbon dioxide (CO 2 ) (−49 ± 66 g C m −2 yr −1 ) and a source of methane (CH 4 ) (19.7 ± 5 g C m −2 yr −1 ), while the nutrient rich industrial cutaway was a net source of CO 2 (0.66 ± 168 g C m −2 yr −1 ) and CH 4 (5.0 ± 2.2 g C m −2 yr −1 ). The rewetted domestic cutover site exhibited the expected range of micro-habitats and species composition found in natural (non-degraded) counterparts. In contrast, despite successful rewetting, the industrially extracted peatland did not exhibit typical raised bog flora. This study demonstrated that environmental and management variables can influence species composition and, therefore, the regeneration of species typical of natural sites, and has highlighted the climate benefits from rewetting degraded peatlands in terms of reduced GHG emissions. However, rewetting of degraded peatlands is a major challenge and in some cases reintroduction of bryophytes typical of natural raised bogs may be more difficult than the achievement of proper GHG emission savings. Environmental Protection Agency Bord na Móna

Availability of reactive nitrogen (Nr; mainly ammonium, NH4+, and nitrate, NO3−) via precipitation and upwelling groundwater affects carbon (C) accumulation in peat deposits and biological greenhouse gas emissions. Isotope composition of Nr was studied at Wolf Swamp (WS) and The Glades (GL), two peatlands located in western Maryland (U.S.), to provide a more robust understanding of N cycling at the ecosystem level. In recent years, both sites experienced a moderate atmospheric pollution (3–9 kg of deposited Nr ha−1 yr−1), and possible additional Nr inputs via groundwater contaminated by fertilizers/livestock. Sampling of living Sphagnum, vertical peat profiles, atmospheric deposition, and surface bog water was carried out on October 22–24, 2017. The δ15Nr signatures of vertical precipitation were negative (mass-weighted means of −7.2 and −8.1‰ at WS and GL, respectively) despite reports that NOx emitted by coal-burning power plants, a precursor of deposited nitrate, had been extremely positive (up to +26‰). Mean δ15N values at both sites increased in the order: vertical precipitation

The inorganic content of the well-preserved 3.2-m record of Las Conchas bog (NW Spain), covering 8000 cal yr BP., was analysed. To study natural vs. human contributions, we applied an innovative approach, namely the sequential study of multivariate statistics (factor analysis followed by clustering of the factor score matrix) and enrichment factors (EFs). The increasing weight of potentially toxic elements (PTEs) such as the geochemical association of Zn, Pb and Cd (EFs higher than 10, 20 and 40 in the last two centuries) was revealed, and corroborated by the contrast between the contents of anthropogenic Pb and total Rare Earth Elements (a suitable proxy for natural geogenic supplies). Furthermore, elements such as Hg, Tl and As also showed enrichment in the most recent samples of the study core. Some of them are commonly associated with global atmospheric transport; however, in this case, their increasing contents could also be explained by nearby industrial and mining activities. In summary, severe pollution was observed in the uppermost part of the record, thereby pointing to an important environmental concern. Given that local and regional sources of PTEs, such as mining and heavy industry, especially Zn smelting, were probably the main historical causes of this contamination and that some of these industries are still active, we consider that our findings deserve further attention., This paper was funded by the Spanish Commission of Science and Technology (CICYT), projects CGL2013-46458-C1-1-R and CGL2013-46458-C2-2-R.

[EN] The northwest region of the Iberian Peninsula is home to a unique ecosystem of bogs, which are particularly sensitive to projected climate change. In this context, the rate of carbon (C) accumulation in Chao de Veiga Mol, an intact raised bog, was analysed. Changes in the accumulation rate over the past 10 millennia were determined in a peat core of 847 cm in depth, with a high mean rate of peat growth (11 yr cm1, 0.09 cm yr1). An age-depth model was generated from 22 14C dates and fallout radionuclides. Chronological, stratigraphical and physico-chemical data confirmed the existence of a single cycle of peat formation throughout the Holocene and the formation of ombrotrophic peat 9500 years ago. The total mean C content was 50.2%, and over 10 millennia 583 kg C m2 accumulated at a mean rate of 35.3 g C m2 yr1, with a long-term (apparent) rate of carbon accumulation in the catotelm of 59.9 g C m2 yr1. These values are much higher than reported for other Iberian peatlands and are amongst the highest documented for peatlands in the northern hemisphere. The dynamics of C accumulation and other measured parameters reveals important variations throughout the Holocene. They could be associated with the main climatic events described in the northern hemisphere and are highly consistent with models established for northern latitudes. The Chao de Veiga Mol raised bog is unique and of great potential value for carrying out high resolution palaeoenvironmental studies, especially in relation to regional and local modulations in southern Europe, Los autores agradecen a la comunidad de Santo Tomé de Recaré por permitirnos llevar a cabo esta y otras investigaciones en su propiedad, y a todos los que participaron en el trabajo de campo . Esta investigación fue posible gracias a la recepción de una subvención otorgada por la Xunta de Galicia (proyecto: INCITE09-200-019-PR). Los autores desean agradecer el uso de las instalaciones analíticas RIAIDT-USC y al Prof. Geoff Millward (Universidad de Plymouth) por su ayuda con el espectrómetro gamma . También agradecemos a Christine Francis, traductora nativa, por la revisión y corrección del manuscrito en sus aspectos lingüísticos.

Liquefied natural gas has started to establish itself as the fuel of choice across the globe, evident from its sustained growth over the last three decades. As a result, more regasification terminals are coming up every year. Hence, it is critical to develop technologies which make sure the plants are operated efficiently. This paper studies the generation and management of Boil Off Gases (BOG) in LNG regasification terminals. The effect of time varying ambient temperature on the BOG generation is studied, and ways to improve the operational efficiency of BOG compressors are suggested.

High-resolution studies of peat profiles are frequently undertaken to investigate natural and anthropogenic disturbances over time. However, overlapping profiles of the most commonly applied age-dating techniques, including 14C and 210Pb, often show significant offsets (>decadal) and biases that can be difficult to resolve. Here we investigate variations in the chronometers and individual site histories from six ombrotrophic peat bogs in central and northern Alberta. Dates produced using pre- and post-bomb 14C, 210Pb (corroborated with 137Cs and 241Am), and cryptotephra peaks, are compared and then integrated using OxCal's P_Sequence function to produce a single Bayesian age model. Environmental histories for each site obtained using physical and chemical characteristics of the peat cores, e.g. plant macrofossils, humification, ash content and dry density, provide important constraints for the models by highlighting periods with significant changes in accumulation rate, e.g. fire events, permafrost development, and prolonged surficial drying. Despite variable environmental histories, it is possible to produce high-resolution age-depth models for each core sequence. Consistent offsets between 14C and 210Pb dates pre-1960s are seen at five of the six sites, but tephra-corrected 210Pb data can be used to produce more coherent models at three of these sites. Processes such as permafrost development and thaw, surficial drying and local fires can disrupt the normal processes by which chronological markers and environmental records are incorporated in the peat record. In consequence, applying standard dating methodologies to these records will result in even greater uncertainties and discrepancies between the different dating tools. These results show that using any single method to accurately date peat profiles where accumulation has not been uniform over time may be unreliable, but a comprehensive multi-method investigation paired with the application of Bayesian statistics can produce more robust chronologies. New cryptotephra data for the Alberta region are also reported here, including the historical Novarupta-Katmai 1912 eruption, White River Ash (East), and glass from Mt. St. Helens, Mt. Churchill, and probable Aleutian sources.

Peatlands cover very large extents in northern regions and play a significant role in the global carbon cycle by functioning as a carbon sink. Large-scale satellite based monitoring systems, such as the Sentinel-2 Multispectral Instrument (MSI), are necessary to improve our understanding of how these ecosystems respond to climate change by providing verifiable land products. For instance, satellite-based land product validation approaches can benefit from airborne hyperspectral imagery and in-situ data, which provide higher spatial and spectral resolution baselines, ideal for measuring vegetation changes (e.g. phenology, LAI) at local scales. Here, we assessed the short-term phenospectral dynamics (spectral changes indicated by specific spectral features as a function of phenology) of five ombrotrophic peatland vegetation physiognomies over four dates at the Mer Bleue bog in Canada. We took advantage of a unique remote sensing data acquisition campaign aiming to validate Sentinel-2A land products, and analyzed three spatially and spectrally distinctive datasets (i.e. field spectra, VISNIR airborne hyperspectral imagery (HSI) and Sentinel-2A imagery) over the first half of the 2016 growing season. By implementing a bottom-up approach, first we assessed the airborne HSI's capability to detect phenological changes as compared to in-situ acquired field spectroscopy measurements in a 10 ha area at Mer Bleue and evaluated the spectral features characteristic of these phenological changes. Second, over the entire Mer Bleue area (28,000 ha), we compared a series of four Sentinel-2A images to four airborne HSI mosaics (spatially and spectrally resampled to Sentinel-2A) to assess the utility of Sentinel-2A for detecting small spectral variations due to phenological changes (i.e. greening). In addition, for this second comparison, three spectral vegetation indices were derived from the Sentinel-2A images and the airborne HSI mosaics. The spectral comparisons between the airborne HSI and the field spectroscopy data revealed clear phenological changes from the airborne HSI. For instance, a closer agreement between reflectance measured by the field spectrometer and the airborne HSI spectral response was found in the visible region (450–680 nm). A greater difference however, was consistently seen in the near-infrared region (681–866 nm) across the four dates. Narrow spectral features in three regions of the visible range (global minima, red absorption, green peak), indicating changes in vegetation colour, were consistent for both datasets and with expected phenological patterns at Mer Bleue. At the landscape level, Sentinel-2A mirrored the spectral changes depicted by the resampled HSI data. However, band level, pair-wise comparisons showed significant differences (p

Boil-off gas (BOG) generation is inevitable in LNG regasification terminals, which import and store huge amounts of LNG. The energy and costs required to reliquefy the generated BOG is substantial for a regasification terminal. Consequently, it is important to optimize BOG reliquefaction in regasification terminals. In this work, we develop a novel superstructure for BOG reliquefaction comprising of all the process options discussed in our previous work (Rao et al., 2016) and use a nonlinear programming (NLP) formulation to minimize the total annualized cost (TAC) of the process. We then use a derivative-free optimization approach to solve this simulation-based optimization problem. For a case study terminal (Park et al., 2012), we discuss the optimal configurations for BOG reliquefaction corresponding to varying amounts of BOG in the terminal.

Tropical peatlands hold large amounts of carbon but the influence of litter inputs and variation in peat properties with depth on carbon storage are poorly understood. Here we present a stratigraphy of peatland carbon stocks and accumulation through the peat profile in a tropical ombrotrophic wetland and assess shifts in vegetation inputs and organic matter degradation using n-alkane distributions and Rock-Eval 6 pyrolysis. Mixed forest (including canopy palms and tropical hardwood trees) contained the greatest total carbon stock in the soil (1884 Mg C ha−1), followed by Rhizophora mangle (mangrove, 1771 Mg C ha−1), Campnosperma panamensis (hardwood, 1694 Mg C ha−1) and Cyperus (sawgrass) bog plain (1488 Mg C ha−1). The long-term apparent rate of carbon accumulation, determined by 14C dating of the carbon stored in different layers in the peat profile, decreased from the edge to the interior of the peatland, with the highest accumulation rate in at the Rhizophora site (102.2 g C m−2 y−1) and the lowest in the deeper peat layers at the Cyperus site (45.6 g C m−2 y−1). High molecular weight n-alkanes dominated in surface peat in all four phasic communities, while deeper in the peat profile n-alkane profiles differed more among sites, suggesting contrasting litter inputs or decomposition environments. Deeper peat was depleted in carbohydrates and had a relatively larger thermostable C pool. Taken together our findings show (i) that different forest types hold varying C stocks and have different peat accumulation rates, even over relatively small distances, and (ii) progressive depletion of carbohydrates and thermolabile compounds with depth, despite strong variation in litter inputs throughout the peat profile.

BOG (Bacterium and virus analysis of Orthologous Groups) is a package for identifying groups of differentially regulated genes in the light of gene functions for various virus and bacteria genomes. It is designed to identify Clusters of Orthologous Groups (COGs) that are enriched among genes that have gone through significant changes under different conditions. This would contribute to the detection of pathogens, an important scientific research area of relevance in uncovering bioterrorism, among others. Particular statistical analyses include hypergeometric, Mann–Whitney rank sum, and gene set enrichment. Results from the analyses are organized and presented in tabular and graphical forms for ease of understanding and dissemination of results. BOG is implemented as an R-package, which is available from CRAN or can be downloaded from http://www.stat.osu.edu/~statgen/SOFTWARE/BOG/.

We examined the effects of long-term (51 years) drainage on peat microbial communities using phospholipid fatty acid (PLFA) analysis. We analysed the peat profiles of natural and adjacent drained fen and bog sites. Viable microbes (i.e. microbial PLFA) were present in relatively large amounts even in the deepest peat layers of both peatland sites, a finding that warrants further investigation. Microbial biomass was generally higher in the fen than in the bog. Microbial community structure (indexed from PLFA) differed between the fen and bog sites and among depths. Although we did not exclude other factors, the effect of drainage on the total microbial biomass and community structure was not limited to the surface layers, but extended to the deepest layers of the fen and bog. Long-term drainage increased the total microbial PLFA biomass in the surface, subsurface and bottom layers of the fen, but decreased it in the surface and bottom layers of the bog site. Drainage also increased the characteristic FAs of Gram-positive and Gram-negative bacteria in the surface and subsurface layers of the fen, and decreased them in the bottom layers of the bog site. The characteristic fungal FA was only reduced in the surface layers of the bog site by drainage. Thus, by affecting the microbial community beyond the surface layers, long-term peatland water-level draw-down can alter the microbial contribution to deeper peat organic matter stabilization. This suggests that long-term drainage may have a more significant climate change effect than revealed by the surface layer analyses alone. acceptedVersion

Nitrogen (N) deposition is a major cause of plant biodiversity loss, with serious implications for appropriate management of protected sites. Reducing N emissions is the only long-term solution. However, on-site management has the potential to mitigate some of the adverse effects of N deposition. In this paper we review how management activities such as grazing, cutting, burning, hydrological management and soil disturbance measures can mitigate the negative impacts of N across a range of temperate habitats (acid, calcareous and neutral grasslands, sand dunes and other coastal habitats, heathlands, bogs and fens). The review focuses mainly on European habitats, which have a long history of N deposition, and it excludes forested systems. For each management type we distinguish between actions that improve habitat suitability for plant species of conservation importance, and actions that immobilize N or remove it from the system. For grasslands and heathlands we collate data on the quantity of N removal by each management type. Our findings show that while most activities improve habitat suitability, the majority do little to slow or to reduce the amount of N accumulating in soil pools at current deposition rates. Only heavy cutting/mowing with removal in grasslands, high intensity burns in heathlands and sod cutting remove more N than comes in from deposition under typical management cycles. We conclude by discussing some of the unintended consequences of managing specifically for N impacts, which can include damage to non-target species, alteration of soil processes, loss of the seedbank and loss of soil carbon.

Five wetland restoration projects—saline tidal marsh, freshwater marsh, peat bog, forested wetland, and urban wetland—illustrate the techniques and challenges associated with their restoration and ecosystem development. Techniques include hydrologic restoration by site grading and excavation to restore tidal inundation of saline marshes and plugging ditches to restore freshwater marshes and peat bogs. Active management, transplanting seedlings and introducing seed mixtures, is used to accelerate development of the plant community in saline tidal marshes and freshwater marshes, respectively, whereas reestablishment of vegetation in peat bogs involves natural colonization and succession. In urban landscapes, stream and riparian restoration of forested wetlands and removal of fill during brackish marsh restoration are necessary to establish antecedent hydrology favorable for desired vegetation. Removal of invasive species prior to restoration also is necessary in urban environments. Control of herbivores and invasive species also may be needed. Ecosystem development proceeds at different rates in different wetlands. Saline tidal marshes with their predictable hydrology develop faster than wetlands such as peat bogs and freshwater marshes where hydrology is less predictable and is driven by precipitation.

Hydrology controls the physical, chemical and biological processes in peatlands and hence could be the most important process regulating their function, development and characteristic biogeochemistry. Models describing hydrological processes and soil heat exchange phenomena are an important tool in understanding the peatland biogeochemical cycles of C and N. Presented in this paper is a peat soil climate model that uses weather data, mire site and peat characteristics as input data. The model is related to the heterogeneous peat characteristics (e.g. bulk density, degree of humification, remains of Sphagnum , Carex , Eriophorum and woody tissues), which in turn vary with depth. Evapotranspiration is related to weather parameters and tree stand characteristics. The model simulations were validated against the observed data collected during 1993 and 1994 growing seasons at a fen and bog sites at the Lakkasuo mire complex located in central Finland. The observed and simulated day-to-day variations in water table levels and soil temperatures during both seasons appeared overall to be in phase. As the model lacks the data needed to characterize the peat matrix hysteresis, the model was found lacking in response to wetting and drying cycles. The mean differences between simulated and observed water table levels during 1994 were −0.3 ± 1.3 and −0.5 ± 2.3 cm for the fen and bog sites, respectively. The model was found to be sensitive to mire surface characteristics and evapotranspiration, particularly for the bog site with an unsaturated zone deeper than at the fen. The absolute mean differences between the simulated and measured peat temperatures from 5 to 150 cm were less than 1.0 °C with a maximal standard deviation of 1.6 °C. The model deviations for the upper layers showed larger variations compared to deeper layers, implying a greater accuracy in defining the lower boundary of the thermal regime within the peat column.

Fluorescence microscopy of fossil pollen and spores has only been exploited by palynologists for geological time scales. A reconstruction of ecological change, blanket peat erosion and consequent sediment flux within an area of moorland in the north of England during the late Holocene has provided an opportunity to evaluate whether fluorescence microscopy of pollen and spores can be used as a tool for reconstructing environmental change at shorter and more recent timescales. The fluorescence properties of pollen and spores in samples of blanket peat (sediment source) and reservoir sediments (sediment sink) were assessed during routine pollen counts. Fluorescence varied with taxon. Bog surface processes such as moorland fire and dessication were observed to have no visible effect on fluorescence, but air pollution deposition (indicated by Pb) did have an effect, although exactly which pollutant(s) is responsible is unclear. The effect on fluorescence of the physical processes associated with peat erosion and re-sedimentation in reservoirs was examined. Spores of lower plants found in reservoir sediment samples with a high content of eroded peat were well preserved (fluorescing at blue-green wavelengths), suggesting that the eroded peat was transported from the bog surface to the reservoir as peat fragments containing pollen and spores. There is a direct correlation between the proportions of pollen and spores with extinguished fluorescence (very poor preservation state) in sediment samples, and sediment accumulation rate. This relationship is probably not applicable for quantitatively estimating sedimentation rate at other sites due to the effect of local factors. However, the relationship can provide the basis for a simple, quick and relatively inexpensive method of examining qualitative shifts in sediment flux, which can be conducted during routine pollen counts.

The net accumulation of remains of Sphagnum spp. is fundamental to the development of many peatlands. The effect of polyphenols from Sphagnum on decomposition processes is frequently cited but has barely been studied. The central area of the Rodmossamyran peatland (Sweden) is an open lawn that consists mostly of Sphagnum spp. with a very low contribution from vascular plants. In order to determine the effects of decay on sphagnum phenols, 53 samples of a 2.7 m deep core from this lawn were analysed with pyrolysis gas chromatography–mass spectrometry (pyrolysis-GC–MS) and compared with more traditional decomposition proxies such as C/N ratio, UV light transmission of alkaline peat extracts, and bulk density. Factor analysis of 72 quantified pyrolysis products suggested that the variation in 4-isopropenylphenol was largely determined by aerobic decomposition instead of Sphagnum abundance. In order to evaluate the effects of aerobic decay in Sphagnum peat, down-core records from different climatic regions were compared using molecular markers for plant biopolymers and C/N ratio. These included markers for lignin from vascular plants ((di)methoxyphenols), polyphenols from Sphagnum spp. (4-isopropenylphenol), and cellulose (levoglucosan). Our results indicate that polyphenols from Sphagnum are preferentially degraded over polysaccharides; consequently the variability of the marker for sphagnum acid, 4-isopropenylphenol, was found indicative of decomposition instead of reflecting the abundance of Sphagnum remains. The fact that 4-isopropenylphenol is aerobically degraded in combination with its specificity for Sphagnum spp. makes it a consistent indicator of past hydrological conditions in Sphagnum-dominated peat. In contrast, the variability of C/N records in Sphagnum-dominated peat was influenced by both vegetation shifts and decomposition, and the dominant effect differed between the studied peatlands. Our results provide direction for modelling studies that try to predict possible feedback mechanisms between peatlands and future climate change, and indicate that the focus in Sphagnum decay studies should be on carbohydrates rather than on phenolic compounds.

Much experience has been gained on vacuum consolidation (preloading) of soft clayey deposits and hydraulic fills, particularly over the past three decades. The benefits of this technique over other forms of ground improvement have become clearer and it is now widely accepted as a useful and practical technique for reducing postconstruction settlement for such deposits. However, to date, only a handful of investigations have considered its use for peat bogs and other highly organic deposits, which present some of the most problematic ground conditions. This chapter describes some pertinent geotechnical properties of peat deposits, followed by a review of the literature on vacuum consolidation in peat, focusing on the vacuum consolidation set up and issues affecting the system performance. Based on the limited field data, for jet pump-centrifugal pump systems, an average vacuum pressure of typically 50 kPa seems appropriate for peat in design, although higher suctions may be considered for a jet pump-liquid ring pump combination. Since bogs are dynamic ecohydrological systems, it is important to understand their morphology (formation/botanical composition) and hydrology in assessing field performance.

The generalization of data on bog water chemistry has been performed in taiga zone of Western Siberia within 1998–2011. It is shown that the decrease in dissolved salt concentrations over the territories included in the row «eutrophic swamp – mesotrophic swamp – oligotrophic bog» is observed in the course of deterioration of water-mineral supply for bog plants, in the cross-section of peat formation – from inert layer to the upper part of active layer. It is stated that during a year there are maximums in trace element contents, biogenic matter, organic acids in spring and most of principle ions – in summer.

Biological material as a proxy of climate spans a wide range of subdisciplines. Here, we focus on the record provided by insects, rodent middens, and other terrestrial biological evidence, including treeline changes, and the paleoclimatic records provided by peat bogs (mires).

Peat landslides form a distinct suite of slope failures that are characteristic of landscapes where organic soils dominate. Six main types of peat mass movement are recognized: bog burst, bog flow, bog slide, peat slide, peaty-debris slide, and peat flow. Such failures have been prevalent in the British Isles, but their occurrence globally is far more widespread than hitherto reported. Peat has distinct geotechnical properties that influence its stability and govern the range of impacts of landslide events. Geotechnically, peat is a low density, organic-rich, nonmineral soil, which has a high water content, significant fiber content, high voids ratio, high compressibility, and low shear strength. Peat landslides cause significant environmental impacts at-a-site, and their runout is far traveled causing considerable downstream devastation to infrastructure and stream ecology. Peat landslides triggered by construction in upland areas demonstrate the importance of surface/subsurface drainage and surface loading in contributing to failure. Although the general mechanisms of peat failure are now well understood, considerable uncertainties associated with determining geotechnical properties of peat, and adequately assessing the hydrological conditions relating to peat instability remain.

Members of the class Synurophyceae are unicellular or colonial motile flagellates, with one or two golden-colored plastids and a cell covering of siliceous scales. The scales are highly organized on the cell and form species-specific designs used to identify each taxon. Informally, the organisms are often referred to as scaled chrysophytes. There are more than 220 recognized species or sub-specific taxa, the vast majority belonging to Mallomonas and Synura. Synurophyceae are common euplanktonic organisms found in ponds, lakes, bogs, and wetlands, as well as in slowly flowing streams and rivers. Habitats supporting the richest floras are generally slightly acidic; are low in specific conductance, alkalinity, and nutrient content; and have moderate concentrations of humic substances. Because numerous species have limited distributions along various environmental gradients, synurophytes are excellent bioindicators and are often used in paleolimnological studies. This chapter provides a classification of the Synurophyceae, with descriptions of their morphology, reproduction, ecology, and distribution.

International audience; There is now a plethora of records of atmospheric metal deposition across Europe based on total concentrations and calculated enrichment factors. However, to place such records into an archaeological context and to identify anthropogenic contamination signals more accurately, it is important to separate the signals derived from anthropogenic activities from those of a natural origin. This study presents a new 3300-year record from a bog in the vicinity of Hadrian's Wall and the Northern Pennine orefield in order to generate a new atmospheric metal deposition record for this archaeologically important part of the British Isles. For this purpose multi element geochemistry was undertaken to apportion the contribution of trace metals (lead, zinc, copper, arsenic and mercury) and sulphur as a result of mining/metallurgy and/or geogenic processes. To extract the different contributions through time we used total concentrations and enrichment factors (EF), and applied principal component analysis (PCA) to the dataset. The PCA extracted 7 components: at least two components are necessary to elucidate the trace metal distribution. Zinc, arsenic and lead are mostly related to atmospheric pollution, while mercury and copper appear to be more closely associated with organic matter. Based on these results four phases of lead contamination have been identified that date to: I, c. 2350–1500 cal BP; II, c. 1050–700 cal BP; III, c. 500–350 cal BP and IV, 250 cal BP–present. Copper enrichment also occurs during the Bronze Age (c. 3150–2800 cal BP). Peaks in other metals do not always correspond with lead and they may have been caused by other land use changes or processes that operate internally within the bog. Although the lead can be attributed to both anthropogenic and geogenic sources, its down profile pattern is in accordance with contamination records elsewhere in Britain and Europe, and the lead enrichment recorded at Raeburn Flow suggests that the Northern Pennine orefield was exploited for metals during the late Iron Age and Roman period.

Publisher Summary This chapter describes the botany of Bristol. The neighborhood of Bristol possesses a widely varying physical configuration, geological structure, and furnishes nearly every kind of locality that a botanist desires for his researches. One may even say that the additions of mountain and bog are mainly required to render the Bristol district a typical portion of Great Britain. The distribution of plants being largely dependent on the nature of these features, the flora is, as might be expected, proportionately extensive. The Flora of the Bristol Coal-fields, published by the Bristol Naturalists' Society, with its supplements, contains records of about 1,020 flowering plants and vascular cryptogams. Four species found in the district do not grow elsewhere in Britain. They are Dianthus casius, Stachys alpina, Arabis stricta, and Allium spharocephalum, the last being peculiar to St. Vincent's Rocks and Durdham Down.

Knowledge of the varying patterns of thermokarst landforms, their dynamic processes, and terrain and ecological factors affecting development is essential to understand the response of polar ecosystems to climate change and human impacts. Studies from Arctic, Subarctic, and Antarctic regions have identified 23 thermokarst landforms associated with varying terrain conditions, ground ice volumes and morphologies, and heat and mass transfer processes. These include: deep thermokarst lake, shallow thermokarst lake, glacial thermokarst lake, glacial thermokarst, thermokarst basin, thermokarst-lake basin, thaw sink, thermokarst fen, thermokarst bog, thermokarst shore fen, thaw slump, detachment slide, collapsed pingo, beaded stream, thermal erosion gully, thermokarst water track, collapse-block shore, ice-block landslide, thermokarst troughs and pits, thermokarst pits, conical thermokarst mounds, irregular thermokarst mounds, and sink holes. Thermokarst development variously involves the transfer of heat through conductive, convective, and radiative processes, and the movement of materials through fluvial and colluvial geomorphic processes. Permafrost degradation is a highly dynamic process that involves continual changes in surface topography, surface water, groundwater, soil properties, vegetation, and snow, and, thus, energy balance and heat transfer processes, which can be subject to both positive and negative feedbacks. Owing to these dynamics, thermokarst goes through temporal changes involving initial and advance stages of degradation and stabilization, but recovery to original permafrost and ecological conditions is rare.

This study considers gamma ray attenuation in relation to the soils and bedrock of Northern Ireland using simple theory and data from a high resolution airborne survey. The bedrock is considered as a source of radiogenic material acting as parent to the soil. Attenuation in the near-surface is then controlled by water content in conjunction with the porosity and density of the soil cover. The Total Count radiometric data together with 1:250 k mapping of the soils and bedrock of Northern Ireland are used to perform statistical analyses emphasising the nature of the low count behaviour. Estimations of the bedrock response characteristics are improved by excluding areas covered by low count soils (organic/humic). Equally, estimations of soil response characteristics are improved by excluding areas underlain by low count bedrock (basalt). When the spatial characteristics of the soil-classified data are examined in detail, the low values form spatially-coherent zones (natural clusters) that can potentially be interpreted as areas of increased water content for each soil type. As predicted by theory, the highest attenuation factors are associated with the three organic soil types studied here. Peat, in particular, is remarkably skewed to low count behaviour in its radiometric response. Two detailed studies of blanket bogs reveal the extent to which peat may be mapped by its radiometric response while the intra-peat variations in the observed response may indicate areas of thin cover together with areas of increased water content.

Large areas of Great Britain currently receive nitrogen (N) deposition at rates which exceed the thresholds above which there is risk of damage to sensitive components of the ecosystem (critical loads for nutrient nitrogen and critical levels for ammonia), and are predicted to continue to do so. Excess N can damage semi-natural ecosystems. Lichens are potentially sensitive to air quality because they directly utilise nutrients deposited from the atmosphere thus may be good indicators of air quality. We used data from the British Lichen Society (BLS) database, which records the presence of all lichen taxa growing in Britain at 10 km resolution. The probability of presence of a taxa at a given level of N deposition was analysed together with driver data for climate, change in sulphur deposition, land-use and N deposition using generalised additive models (GAMs). Many taxa showed negative responses to N deposition with reductions in the probability of presence as N deposition increased. In all of the habitats, there were a mix of terricolous taxa which showed negative or no significant relationship with N deposition. Most of the taxa with negative relationships with N deposition started to decline in prevalence at the lowest levels of deposition found in this study. Levels of deposition over which a negative response apparently occurs are lower than those at which critical loads have been set for some habitats. These findings suggest that some terricolous lichen taxa are sensitive to atmospheric N deposition and even low levels of nitrogen deposition could be damaging terricolous lichen communities making then potentially good indicators of N deposition.

Generation of Boil-off gas (BOG) in liquefied natural gas (LNG) receiving terminal affects considerably operating energy costs and safety issue. For that reason, the BOG handling method is determinant for design of LNG receiving terminal. This study proposes the concept of new design for BOG handling and calculates the design variables using sensitivity analysis for minimum send-out case. This design provides 21.9% energy saving and 0.197y payback period.

The study of macroscopic charcoal particles from peat bogs has led to a better understanding of climate, vegetation and fire history, and human impacts. To determine the relationship between human activities and the role of fire events in vegetation change during the last 3300. cal yr BP, we present the results of a multi-proxy approach based on the analysis of sediment characteristics, sedimentary charcoal, organic matter and pollen, as well as historical sources. This multi-proxy research permits high resolution palaeoenvironmental and fire history reconstruction of a mountain area located in the southern central Pyrenees (Spain). In the Pyrenees, fire is typically attributed to human activities since the beginning of the Bronze Age and may be correlated with slash-and-burn cultivation, metallurgy and pasturing activities. The data indicate a good linkage between high fire signals and Poaceae and Cerealia pollen, which reveals the impact of agro-pastoral practices. This study also shows two periods, 2900-2650. cal yr BP and 1850-1550. cal yr BP, for which higher frequencies of fire occurred, suggested by high arboreal pollen (AP) concentrations, and confirming the need for arboreal biomass to sustain fires. From the beginning of the Middle Ages, it seems that a change occurred in the anthropogenic use of fire, from a tool for agro-pastoral forest clearance to a means of maintaining open spaces. © 2011 Elsevier B.V., This work was supported by 1) a research grant from the Comunitat de Treball dels Pirineus (2007ITT 00001): Environmental dynamic of the Pyrenees over the past 20,000 years: A study of the impact of changes in climate and land use on forest ecosystems for the development of possible scenarios (Dinàmica ambiental pirinenca dels darrers 20.000 anys: estudi de l'impacte dels canvis climàtics i dels usos del sòl sobre els ecosistemes forestals per a l'elaboració d'escenaris prospectius) and 2) a project of the Catalan government (Generalitat de Catalunya — 2006EXCAVA00022): Archaeology of the high Pyrenees mountains.