Adjacent Peatland Research Articles

Effects of road dust on vegetation composition and surface chemistry of three ombrotrophic peatlands in eastern Canada

Dust deposition can fertilize nutrient-limited peatlands and affect their plant assemblages and ecosystem functions, but the effects of local road dust on peatlands have seldom been studied. Here, we investigate the responses of vegetation composition and surface chemistry (vegetation, surface peat, and groundwater chemistry) at three ombrotrophic peatlands: Rivière-au-Tonnerre (RT), Chemin de l'Anse-de-la-Grande-Pointe (GP), and Kegaska (KEG) in eastern Québec, Canada, to varying levels of road dust deposition with differential chemical composition. At each site, a transect aligned with the dominant wind direction, starting at and perpendicular to the roadside, was sampled at increasing intervals up to 250 m away from the gravel (unpaved) road. We find that the ash content of surface peat is highest closest to the roads at all three sites and decreases exponentially with increasing distance up to 200 m away from the roads. At KEG, with the highest amount of, and the most phosphorus (P) rich, road dust deposition, the ash content is highest among the three sites, decreasing most rapidly with distance away from the road. The stoichiometric mass ratios of carbon (C), nitrogen (N) and P, i.e., C:N, C:P, and N:P, in foliar tissues and surface peat increase significantly with distance away from the road at KEG, and mosses are found to be more responsive in terms of foliar chemistry than shrubs to the road dust deposition. A higher concentration of total dissolved phosphorus at KEG is found closer to the road. At GP, having a moderate amount of road dust deposition, significant increases in C:N, C:P, and N:P ratios with distance are found only in surface peat but not in foliar tissues. Due to the presence of carbonate minerals in the road dust of GP, the calcium (Ca) concentration and pH value of groundwater closer to the road are higher, leading to an obvious loss of vegetation coverage, especially mosses, and a consequent increase in NO3− leaching. In contrast, at RT, having the lowest amount of road dust deposition, only a few clear variation patterns in surface chemistry are found along the sampling transect. Overall, our results suggest that dust from gravel roads can be an important localized source of nutrients for adjacent peatlands and influence their vegetation composition and surface chemistry, depending on the amount of road dust and its chemical composition, especially its contents in Ca and P.

Response of rove-beetle (Staphylinidae) assemblages to the cumulative effect of wildfire and linear footprint in boreal treed peatlands.

Cumulative effects of anthropogenic and natural disturbances have become increasingly relevant in the context of biodiversity conservation. Oil and gas (OG) exploration and extraction activities have created thousands of kilometers of linear footprints in boreal ecosystems of Alberta, Canada. Among these disturbances, seismic lines (narrow corridors cut through the forest) are one of the most common footprints and have become a significant landscape feature influencing the maintenance of forest interior habitats and biodiversity. Wildfire is a common stand-replacing natural disturbance in the boreal forest, and as such, it is hypothesized that its effects can mitigate the linear footprint associated with OG exploration, but only a few studies have examined its effectiveness. We studied the short-term (1year post-fire) response of rove-beetle assemblages to the combined effects of wildfire and linear footprint in forest, edge, and seismic line habitats at burned and unburned peatlands along the southwest perimeter of the 2016 Horse River wildfire (Fort McMurray). While rove-beetle species richness was higher in seismic lines in both the burned and unburned habitats compared with the adjacent peatland, diversity was greater only in seismic lines of burned areas. Abundance was lower in the burned adjacent peatland but similarly higher in the remaining habitats. Assemblage composition on seismic lines was significantly different from that in the adjacent forest and edge habitats within both burned and unburned sites. Moreover, species composition in burned seismic lines was different from either unburned lines or burned forest and edge. Euaesthethus laeviusculus and Gabrius picipennis were indicator species of burned line habitats, are sensitive to post-fire landscapes and can occupy wet habitats with moss cover more efficiently than when these habitats are surrounded by unburned forest. Although these results are based on short-term responses, they suggest that wildfire did not reduce the linear footprint, and instead, the cumulative effect of these two disturbances had a more complex influence on rove-beetle recovery at the landscape level than for other invertebrates. Therefore, continued monitoring of these sites can become useful to evaluate changes over time and to better understand longer-term biodiversity responses to the cumulative effects of wildfire and linear disturbances in boreal treed peatlands, given the long-lasting effect of such disturbances.

Reestablishment of peatland vegetation following surface leveling of decommissioned in situ oil mining infrastructures

Peatland ecosystem restoration following oil mining activities in Alberta, Canada, aims at reestablishing crucial peatland functions, such as wildlife habitat, water storage and filtration, peat accumulation, and carbon sequestration. To reinstate peatland functions, characteristic hydrological conditions are necessary to support the establishment and growth of characteristic wetland vegetation. Following in situ oil sands well pad disturbances in the Peace River and Cold Lake Oil Sands regions in Alberta, we evaluated the efficiency of peatland restoration approaches including different groundwork and revegetation techniques. Groundwork techniques included the complete removal (CR) or partial removal (PR) of the former in situ well pads' mineral fill and revegetation included the spontaneous revegetation via natural ingress of diaspores from nearby peatlands, or managed revegetation via planting of Carex aquatilis, Larix laricina, and Salix lutea. We assessed the plant species composition, biochemical and hydrological properties of all study areas, including restored peatland areas, an unrestored area, and reference areas (REF) for comparison. Ten years post‐restoration, in the restored areas the mean total plant cover was 57% with an average of 35 vascular plant and bryophyte species, while in REF 68% mean total plant cover and an average of 64 plant species were recorded. Respectively, characteristic peatland species contributed to 61 and 100% of the species composition. PR and hydrological connection to the adjacent peatland resulted in near surface water table and the highest peatland plant species diversity, while CR promoted the formation of a shallow open water area.

Hummock-scale controls on groundwater recharge rates and the potential for developing local groundwater flow systems in water-limited environments

We use two-dimensional numerical models to identify controls on groundwater recharge, water table dynamics, and the sink-source function of fine-textured hummocks in water-limited environments. A silty clay loam hummock with aspen forest cover in the sub-humid Boreal Plains region of Canada is used to develop a conceptual model and calibrate a variably-saturated flow model to better investigate the dynamics of recharge, water table position, and lateral flow between the forested hummock and adjacent peatland. Scenario testing (achieved by raising and lowering the hydraulic conductivity by an order of magnitude and altering the hummock height and length) provides further understanding of the controls that hydraulic conductivity and hummock morphometry exert on recharge and forestland-peatland interactions. We find that the hydraulic conductivity of the glacial till has the largest control over recharge, followed by the hummock height and length and, lastly, annual atmospheric fluxes. Hummocks with higher hydraulic conductivity or long morphometric profiles are most often sinks of water as they promote increased root-water uptake, while taller hummocks with lower hydraulic conductivity tend to act as hydrologic sources for adjacent wetlands. The magnitude of annual recharge and water table elevation are poorly correlated with annual atmospheric fluxes due to the strong effects of multi-year storage deficits or surpluses; however, they are appreciably affected by decadal wet-dry cycles typical of the Boreal Plains climate. Additionally, we show that both distance along a hummock and elevation are key factors in controlling the spatial distribution of recharge at a single hummock. It is common to conceptualize the water table as a shallow and subdued replica of surface topography, where water flows from topographic highs (i.e., forestlands) to topographic lows (i.e., peatlands) in humid environments; however, as we show here, recharge rates, water table elevation, and the sink-source function of a forested hummock in water-limited environments is highly variable in time and space, and strongly dependent on both the hydrogeological and morphometric properties of the hummock.

Kaleka Agroforest in Central Kalimantan (Indonesia): Soil Quality, Hydrological Protection of Adjacent Peatlands, and Sustainability

Increased agricultural use of tropical peatlands has negative environmental effects. Drainage leads to landscape-wide degradation and fire risks. Livelihood strategies in peatland ecosystems have traditionally focused on transitions from riverbanks to peatland forests. Riparian ‘Kaleka’ agroforests with more than 100 years of history persist in the peatlands of Central Kalimantan (Indonesia), where large-scale open-field agricultural projects have dramatically failed. Our field study in a Dayak Ngaju village on the Kahayan river in the Pulang Pisau district involved characterizing land uses, surveying vegetation, measuring soil characteristics, and monitoring groundwater during a period of 16 months. We focused on how local practices and farmer knowledge compare with standard soil fertility (physical, chemical, biological) measurements to make meaningful assessments of risks and opportunities for sustainable land use within site-specific constraints. The Kaleka agroforests around a former settlement and sacred historical meaning are species-rich agroforests dominated by local fruit trees and rubber close to the riverbank. They function well with high wet-season groundwater tables (up to −15 cm) compatible with peatland restoration targets. Existing soil quality indices rate the soils, with low soil pH and high Alexch, as having low suitability for most annual crops, but active tree regeneration in Kaleka shows sustainability.

Seismic line edge effects on plants, lichens and their environmental conditions in boreal peatlands of Northwest Alberta (Canada)

Boreal peatlands of Alberta (Canada) are heavily dissected by a large network of linear disturbances, including seismic lines used for Oil and Gas exploration. Edge effects resulting from these linear disturbances can increase their footprint and affect wildlife habitat, including the quality and quantity of plant and lichen forage. In 2012, seismic line restoration became a priority in Alberta, under the realm of restoration of habitat of threatened boreal woodland caribou. More accurate understanding of biotic and abiotic interactions leading to edge effects can be important in choosing appropriate restoration practices and prompting natural regeneration. We assessed the extent of edge effects of seismic lines on the adjacent boreal peatland near Peace River, northwestern Alberta. We compared plant and lichen community composition and environmental conditions on seismic lines and along 22 transects, which extended perpendicularly 75 m into the peatland from both lines edges. Soil moisture and light were higher on the lines, but frozen ground was less frequent than in the adjacent peatland. Seismic lines were also subsided by approximately 1.2 cm. Lichens were less abundant in the 2–25 m zone from the edge—indicating edge effects. On the lines,Sphagnumconstituted a nearly 100% cover while lichens, trees, herbs, and other bryophytes were less abundant than in the peatland. We demonstrate how knowledge of edge effects on plants and lichens could be applied in assessing caribou habitat quality based on forage availability and predation risk, and how such knowledge could inform restoration practices of seismic lines in peatlands.

The Burial Under Peat Technique: An Innovative Method to Restore Sphagnum Peatlands Impacted by Mineral Linear Disturbances

Mineral roads in peatlands change the nature of the substrate, influence the water table level of the peatland on either side of the road and the physicochemical characteristics of the water and peat. These changes can in turn affect plant community composition. The efficiency of an innovative and affordable method for the restoration of peatlands impacted by roads was evaluated: the Burial Under Peat Technique. To be considered effective from an ecological point of view, the technique should meet restoration goals by 1) confining the chemical elements and compounds potentially leaching from the mineral material; 2) creating and maintaining a restored surface elevation similar to the adjacent peatland for optimal rewetting; and 3) re-establishing typical peatland vegetation communities. Three years post-restoration, water sampled at various depths and distances to the buried road presented chemical elements and compounds concentrations similar to the means measured in the pristine surrounding peatland for most of the ions analyzed. The different steps of the technique ensured the reestablishment of an elevation similar to the surrounding peatland. The return of peatland plant communities was slow, mainly due to local factors (e.g., presence of drainage ditches). Furthermore, the Burial Under Peat Technique fulfilled the restoration objectives in re-establishing an acid organic soil. Finally, it is a cost-effective method in comparison to completely removing the mineral material and transporting new material to fill the depression left by the excavation of the road.

Hydrological effects of resource-access road crossings on boreal forested peatlands

Resource-access road crossings are expected to alter peatland hydrological properties by obstructing surface and sub-surface water flows. We conducted a multi-year study at two boreal peatlands – a forested bog and a shrubby rich fen near Peace River, Alberta – to study the impacts of resource access roads on the hydrology of adjacent peatland. Field measurements (bi-weekly depth to water table and hydraulic head, one-time hydraulic conductivity) during the growing seasons (May-August) of 2016 and 2017 were taken from sampling plots representing: 1) sides of the road (upstream and downstream); 2) distance from the road (obstruction); and 3) distance from culverts. Compared to the growing season average precipitation for the region of 1.8 mm d−1, the study period had very wet conditions in 2016 (3.7 mm d−1) and dry conditions in 2017 (1.1 mm d−1).In contrast to our assumptions, resource access road disturbed the surface and sub-surface water flow at the bog, but the effect was minimal at the fen as the road orientation was nearly parallel to the flow direction at the latter. At the bog, the shallowest depth to water table position was observed at upstream areas closer to the road, when culverts were located >20 m distance from transects. In contrast, when culverts were present <2 m from the transects, variation in hydrological conditions between upstream and downstream areas were greatly reduced. Our work shows road effects on peatland hydrology could be minimized by aligning roads parallel to the water flow direction when possible. If water flow is perpendicular to the road, adequate spacing and installation of culverts could help to reduce flow obstruction.

Новые исследования городища раннего неолита Каюково-2 на севере Западной Сибири

Purpose. The article presents results of new research at one of the most prominent Early Neolithic enclosed settlements in the North of Western Siberia – the stronghold of Kayukovo-2, which is characterized by a regular architectural plan with one central and five surrounding buildings, pottery of a specific shape and type, including flat as well as conical bases and complex ornamentation, and an original complex of stone artefacts. Results. In 2018, the investigation of building structure no. 4 was continued; for the reconstruction of the paleo-landscape, soil samples were investigated in the adjacent peatland, new radiocarbon dates were obtained, and analyses of the material complex represented by fragments of ceramics, products from clay-like raw materials and clay, stone artefacts, and clusters of small bone fragments was carried out. Building no. 4 was identified as a semi-sunken dwelling structure with a hearth in the centre, a small connecting corridor to building no. 7, and a link to the large central building no. 6. In 2019, new trenches confirmed the existence of a ditch circumscribing the settlement complex. Palaeoenvironmental research shows that during the period of use of the site, the closest water body was located c. 100 m from the terrace shore. The radiocarbon dates available up to now indicate a time of functioning of the ancient settlement in the first centuries of the 6th millennium cal BC. The ceramic material belongs to the complex of early flat-based hunter-gatherer pottery of Western Siberia, a tradition which probably spread from the Baraba forest-steppe and the Ishim region to the Northern Trans-Urals around 6000 cal BC. Conclusion. The reasons for the emergence of the northernmost fortified settlements in Eurasia among hunter-gatherer communities with complex architecture and specific ceramics, the role of internal socio-cultural mechanisms and external influences, and environmental factors in their formation continue to be under discussion and require further research.

Road Crossings Increase Methane Emissions From Adjacent Peatland

AbstractWe conducted a multi‐year study in two boreal peatlands to determine the impacts of resource access roads on methane (CH4) emission from adjacent peatland. Data were collected from transects aligned perpendicular to, and on both sides of two roads, one cutting through a bog and one cutting through a fen and from reference areas at each peatland. During the growing seasons of 2016 and 2017, we measured CH4 flux, water table, and peat temperature every second week. At the bog, the road associated impacts (changes to water table, peat temperature, and vegetation cover) were visible up to 20 m on both sides of the road (disturbed areas) with CH4 emission from disturbed areas being significantly higher compared to the reference areas in both years. There were no significant differences in CH4 emissions from disturbed areas compared to reference areas at the fen due to the limited hydrologic impact of the road crossing at this site. Bog plots located upstream of the road on transects located at &gt;20 m from culverts and closer to the road emitted significantly more CH4 (124.6‐mg CH4·m−2·day−1) than other disturbed (10.2 mg CH4·m−2·day‐1) and reference areas (0.7‐mg CH4·m−2·day−1) due to shallower water table and warmer peat temperature. The road induced CH4 emissions (90.8 and 212.2 kg CH4/year for each kilometer of road, in 2016 and 2017, respectively) indicated that road construction across peatlands enhances CH4 emissions from these ecosystems, creating an additional source of anthropogenic greenhouse gas.

Hydraulic redistribution and hydrological controls on aspen transpiration and establishment in peatlands following wildfire

AbstractIn the sub‐humid Western Boreal Plains of Alberta, where evapotranspiration often exceeds precipitation, trembling aspen (Populus tremuloides Michx.) uplands often depend on adjacent peatlands for water supply through hydraulic redistribution. Wildfire is common in the Boreal Plains, so the resilience of the transfer of water from peatlands to uplands through roots immediately following wildfire may have implications for aspen succession. The objective of this research was to characterize post‐fire peatland‐upland hydraulic connectivity and assess controls on aspen transpiration (as a measure of stress and productivity) among landscape topographic positions. In May 2011, a wildfire affected 90,000 ha of north central Alberta, including the Utikuma Region Study Area (URSA). Portions of an URSA glacio‐fluval outwash lake catchment were burned, which included forests and a small peatland. Within 1 year after the fire, aspen were found to be growing in both the interior and margins of this peatland. Across recovering land units, transpiration varied along a topographic gradient of upland midslope (0.42 mm hr−1) &gt; upland hilltop (0.29 mm hr−1) &gt; margin (0.23 mm hr−1) &gt; peatland (0.10 mm hr−1); similar trends were observed with leaf area and stem heights. Although volumetric water content was below field capacity, P. tremuloides were sustained through roots present, likely before fire, in peatland margins through hydraulic redistribution. Evidence for this was observed through the analysis of oxygen (δ18O) and hydrogen (δ2H) isotopes where upland xylem and peat core signatures were −10.0‰ and −117.8‰ and −9.2‰ and −114.0‰, respectively. This research highlights the potential importance of hydraulic redistribution to forest sustainability and recovery, in which the continued delivery of water may result in the encroachment of aspen into peatlands. As such, we suggest that through altering ecosystem services, peatland margins following fire may be at risk to aspen colonization during succession.

Study of Jinchuan Mire in NE China I: AMS 14C, 210Pb and 137Cs dating on peat cores

This paper presents dating results of AMS 14C, 210Pb and 137Cs methods on two young peat profiles from Jinchuan Mire in southeast Jilin of China. JC1 (50-cm long) from a hummock of the mire covers 1962–2007 CE with an accumulation rate of 1.12 cm/y, whereas JCA (92-cm long) from a lawn site involves a 1000-year record with a mean sedimentation of 0.09 cm/y. Comparison of the dating results of the last 100-y part of the peat cores, chronologies based on the AMS 14C dating are most reliable, because the mobility of 210Pb and 137Cs in peat profiles causes overestimation of depositional rate with the larger errors in the deeper layers. The F14C of peat samples were significantly lower than that of the atmospheric CO2 for the post nuclear bomb period because of three reasons: (1) uptake of old CO2 dissolved in the water by aquatic plants during photosynthesis; (2) long-term mixing of the atmospheric CO2 in multiple year growth of the plants; and (3) perhaps dilution effect caused by strong surface runoff. Among these factors, Factor (1) accounts for the major influence. Hence, a “bomb 14C curve” from a peat profile is necessary for determining post bomb ages. For the pre-nuclear bomb ages, acid-base-acid (ABA) treatment of a peat sample may cause an older-than-true age due to removal of organic acids produced during photosynthesis. This observation calls for detailed investigation of mechanism study and proper pretreatment of peat samples for 14C dating. The large difference of the depositional rates in the same peatland between JC1 and JCA indicates that estimation of carbon storage in a peatland should be based on the database of multiple sites rather than a couple of cores. For the same reason, one should not use a depositional rate either from a core with distance in the same peatland or from an adjacent peatland.

Photosynthesis and Respiration of Baltic Sea Benthic Diatoms to Changing Environmental Conditions and Growth Responses of Selected Species as Affected by an Adjacent Peatland (Hütelmoor).

Eight benthic diatom taxa (Actinocyclus octonarius, Melosira moniliformis, Halamphora sp. 1, Halamphora sp. 2, Navicula perminuta, Navicula phyllepta, Nitzschia dubiiformis, Nitzschia pusilla) were isolated from sediments sampled in the southern coastal brackish Baltic Sea and established as unialgal cultures. The coastal shallow water sampling area lies close to a fen peat site (Hütelmoor) and both are connected through an underground peat layer, which might facilitate organic matter and nutrient fluxes along the terrestrial-marine gradient. The photosynthetic performance of these diatoms was measured at different photon fluence rates (0–1200 μmol photons m–2 s–1, always recorded at 20°C) and different temperatures (5–40°C, always measured at saturating ∼270 μmol photons m–2 s–1), resulting in light saturation points between 32 and 151 μmol photons m–2 s–1 and maximum net primary production rates of 23–144 μmol O2 mg–1 Chl a h–1. None of the species showed severe photoinhibition, and hence all displayed a high photo-physiological plasticity. Photosynthetic oxygen evolution and respirational oxygen consumption between 5 and 40°C revealed eurythermal traits for half of the studied taxa as photosynthetic efficiency was at least 20% of the maximum values at the extreme temperatures. The remaining taxa also indicated eurythermal characteristics, however, photosynthetic efficiency of at least 20% was at a narrower temperature range [5 (10) °C to 30 (35) °C]. Species-specific optimum temperatures for photosynthesis (15–30°C) were always lower compared to respiration (25–40°C). Actinocyclus octonarius and Nitzschia dubiiformis were grown in different defined media, some enriched with Hütelmoor water to test for possible effects of organic components. Hütelmoor water media stimulated growth of both diatom species when kept in a light dark cycle. Actinocyclus octonarius particularly grew in darkness in Hütelmoor water media, pointing to heterotrophic capabilities. The benthic diatoms studied are characterized by high photo-physiological plasticity and a broad temperature tolerance to maintain high primary production rates under wide environmental fluctuations. Organic carbon fluxes from the Hütelmoor into the Baltic Sea may support mixo- and/or heterotrophic growth of microphytobenthic communities. These are essential traits for living in a highly dynamic and variable shallow water environment at the coastal zone of the Baltic Sea.

Comparative methods for reconstructing fire histories at the stand scale using charcoal records in peat and mineral soils

Analysis and 14C dating of charcoal fragments ≥2 mm buried in mineral soils make it possible to obtain a stand-scale portrait of Holocene fires that occurred in well-drained, fire-prone environments, as well as changes in forest stand composition over time, based on botanical identification of charcoals. However, it is not always possible to reconstruct all fire events, due to disturbances that altered soil stratigraphy. In order to evaluate the efficacy of this approach, we conducted a comparative analysis with a proximal environment that presents an a priori continuous stratigraphy of charcoal fragments. For two sites in the coniferous boreal forest of eastern North America, the charcoal record of a forest soil was compared with that of an adjacent peatland margin situated at a distance of 20 m. For both types of sedimentary environments, a similar fire history was reconstructed for a large part of the Holocene. The greatest differences were for the early Holocene period, for which a smaller number of fires was detected in the forest soil compared to the peatland soil. Retracing the oldest fires using mineral soils in a fire prone environment is more difficult, due to charcoal decay that results from repeated fire events. However, forest soils reveal a relatively accurate fire history for subsequent millennia if the number of charcoals dated is sufficiently large. Any accurate reconstruction of the fire history of proximal peatland environments is strongly dependent on continuous stratigraphic units of peat and charcoal. Indeed, the age of charcoal fragments in peat may be different from that of the sedimentary layer in which they are buried due to allogenic disturbances like erosion events caused by deep burning of the organic horizon and other mass wasting events. Despite the large number of 14C dates it requires, analysis of soil macrocharcoal yields a realistic picture of the fire history at the stand scale. The concurrent analysis of macrocharcoal from adjacent peatland deposits may be used as a complement to more accurately record the oldest fire events.

Mature exotic conifer stands have greater catches of the EU-protected Geomalacus maculosus than adjacent peatland or clear-felled stands—implications for forestry

© 2017, INRA and Springer-Verlag France SAS, part of Springer Nature. Key message: Mature exotic Sitka spruce (Picea sitchensis; Bong. Carriere)-dominated stands, particularly trees of greater circumference, result in greater numbers ofGeomalacus maculosus(Allman) captures than adjacent clear-felled stands and adjacent peatland with Before-After-Control-Impact-Paired analysis indicating lower catches ofG. maculosuspost-felling. Context: The discovery of EU-protected Geomalacus maculosus in commercial plantations requires an understanding of the implications of forestry practices for the species within the context of sustainable forest management. Aims: 1.Compare Geomalacus maculosus captures across mature exotic Sitka spruce-dominated stands, previously clear-felled stands and adjacent peatland habitats.2.Assess the suitability, for forest managers, of population estimate models for G. maculosus.3.Assess the implications of felling by comparing relative abundances of G. maculosus directly before and after clear-felling at a mature exotic Sitka spruce-dominated stand. Methods: Geomalacus maculosus catches were compared at four sites across two to three mature (43–45 years old) conifer stands per site, one clear-felled stand per site, and one adjacent peatland per site using refuge traps and hand searching. Capture-mark-recapture studies were undertaken to estimate population sizes. A BACIP (Before-After-Control-Impact-Paired) analysis was undertaken in one forest stand at one forest site to determine impacts of a clear-felling event. Results: Mean catches of Geomalacus maculosus adults in the mature forest stands were over 10 and 11 times greater than mean catches on peatland and clear-fell stands, respectively. The Schnabel model for estimating population size was most suited for mature forest stands but could not be utilised for the other habitats. BACIP analysis showed a significant impact of clear-felling with a 95% reduction in mean G. maculosus catches after a clear-felling event where none of the individuals marked prior to felling were recaptured compared to 21% recapture rates at the control site. Greater tree circumference in mature conifer stands correlated with greater catches. Conclusion: Guidelines are needed to ensure the protection of Geomalacus maculosus in commercial forestry. Interventions could include patch/tall stump retention at final felling and/or translocation of the protected species.

Impact of winter roads on boreal peatland carbon exchange.

Across Canada's boreal forest, linear disturbances, including cutlines such as seismic lines and roads, crisscross the landscape to facilitate resource exploration and extraction; many of these linear disturbances cross peatland ecosystems. Changes in tree canopy cover and the compression of the peat by heavy equipment alter local thermal, hydrological, and ecological conditions, likely changing carbon exchange on the disturbance, and possibly in the adjacent peatland. We measured bulk density, water table, soil temperature, plant cover, and CO2 and CH4 flux along triplicate transects crossing a winter road through a wooded fen near Peace River, Alberta, Canada. Sample plots were located 1, 5, and 10m from the road on both sides with an additional three plots on the road. Productivity of the overstory trees, when present, was also determined. The winter road had higher bulk density, shallower water table, higher graminoid cover, and thawed earlier than the adjacent peatland. Tree productivity and CO2 flux varied between the plots, and there was no clear pattern in relation to distance from the road. The plots on the winter road acted as a greater CO2 sink and greater CH4 source compared to the adjacent peatland with plots on the winter road emitting on average (standard error) 479 (138) compared to 41 (10)mgCH4 m-2 day-1 in the adjacent peatland. Considering both gases, global warming potential increased from 70 to 250gCO2 em-2 year-1 in the undisturbed area to 2100g CO2 em-2 year-1 on the winter road. Although carbon fluxes on any given cutline through peatland will vary depending on level of compaction, line width and vegetation community shifts, the large number of linear disturbances in Canada's boreal forest and slow recovery on peatland ecosites suggest they could represent an important anthropogenic greenhouse gas source.

Post-fire ecohydrological conditions at peatland margins in different hydrogeological settings of the Boreal Plain

In the Boreal Plain of Canada, the margins of peatland ecosystems that regulate solute and nutrient fluxes between peatlands and adjacent mineral uplands are prone to deep peat burning. Whether post-fire carbon accumulation is able to offset large carbon losses associated with the deep burning at peatland margins is unknown. For this reason, we examined how post-fire hydrological conditions (i.e. water table depth and periodicity, soil tension, and surface moisture content) and depth of burn were associated with moss recolonization at the peatland margins of three sites. We then interpreted these findings using a hydrogeological systems approach, given the importance of groundwater in determining conditions in the soil-plant-atmosphere continuum in peatlands. Peatland margins dominated by local groundwater flow from adjacent peatland middles were characterized by dynamic hydrological conditions that, when coupled with lowered peatland margin surface elevations due to deep burning, produced two common hydrological states: 1) flooding during wet periods and 2) rapid water table declines during dry periods. These dynamic hydrological states were unfavorable to peatland moss recolonization and bryophytes typical of post-fire recovery in mineral uplands became established. In contrast, at a peatland margin where post-fire hydrological conditions were moderated by larger-scale groundwater flow, flooding and rapid water table declines were infrequent and, subsequently, greater peatland-dwelling moss recolonization was observed. We argue that peatland margins poorly connected to larger-scale groundwater flow are not only prone to deep burning but also lags in post-fire moss recovery. Consequently, an associated reduction in post-fire peat accumulation may occur and negatively affect the net carbon sink status and ecohydrological and biogeochemical function of these peatlands.

Bacterial production in subarctic peatland lakes enriched by thawing permafrost

Abstract. Peatlands extend over vast areas of the northern landscape. Within some of these areas, lakes and ponds are changing in size as a result of permafrost thawing and erosion, resulting in mobilization of the carbon-rich peatland soils. Our aims in the present study were to characterize the particle, carbon and nutrient regime of a set of thermokarst (thaw) lakes and their adjacent peatland permafrost soils in a rapidly degrading landscape in subarctic Québec, Canada, and by way of fluorescence microscopy, flow cytometry, production measurements and an in situ enrichment experiment, determine the bacterial characteristics of these waters relative to other thaw lakes and rock-basin lakes in the region. The soil active layer in a degrading palsa (peatland permafrost mound) adjacent to one of the lakes contained an elevated carbon content (51 % of dry weight), high C : N ratios (17 : 1 by mass), and large stocks of other elements including N (3 % of dry weight), Fe (0.6 %), S (0.5 %), Ca (0.5 %) and P (0.05 %). Two permafrost cores were obtained to a depth of 2.77 m in the palsa, and computerized tomography scans of the cores confirmed that they contained high concentrations (&gt; 80 %) of ice. Upon thawing, the cores released nitrate and dissolved organic carbon (from all core depths sampled), and soluble reactive phosphorus (from bottom depths), at concentrations well above those in the adjacent lake waters. The active layer soil showed a range of particle sizes with a peak at 229 µm, and this was similar to the distribution of particles in the upper permafrost cores. The particle spectrum for the lake water overlapped with those for the soil, but extended to larger (surface water) or finer (bottom water) particles. On average, more than 50 % of the bacterial cells and bacterial production was associated with particles &gt; 3 µm. This relatively low contribution of free-living cells (operationally defined as the &lt; 1 µm fraction) to bacterial production was a general feature of all of the northern lakes sampled, including other thaw lakes and shallow rock-basin lakes (average ± SE of 25 ± 6 %). However, a distinguishing feature of the peatland thaw lakes was significantly higher bacterial specific growth rates, which averaged 4 to 7 times higher values than in the other lake types. The in situ enrichment experiment showed no difference between organic carbon or phosphorus enrichment treatments at day 5 relative to the control, however there was an apparent increase in bacterial growth rates between days 1 and 5 in the soil and the carbon plus phosphorus enrichments. Collectively these results indicate that particles, nutrients and carbon are released by degrading permafrost peatland soils into their associated thermokarst lakes, creating favorable conditions for production by particle-based as well as free-living aquatic bacterial communities. The reduced bacterial concentrations despite high cellular growth rates imply that there is control of their population size by loss-related factors such as grazing and viral lysis.

Summer fluxes of methane and carbon dioxide from a pond and floating mat in a continental Canadian peatland

Abstract. Ponds smaller than 10 000 m2 likely account for about one-third of the global lake perimeter. The release of methane (CH4) and carbon dioxide (CO2) from these ponds is often high and significant on the landscape scale. We measured CO2 and CH4 fluxes in a temperate peatland in southern Ontario, Canada, in summer 2014 along a transect from the open water of a small pond (847 m2) towards the surrounding floating mat (5993 m2) and in a peatland reference area. We used a high-frequency closed chamber technique and distinguished between diffusive and ebullitive CH4 fluxes. CH4 fluxes and CH4 bubble frequency increased from a median of 0.14 (0.00 to 0.43) mmol m−2 h−1 and 4 events m−2 h−1 on the open water to a median of 0.80 (0.20 to 14.97) mmol m−2 h−1 and 168 events m−2 h−1 on the floating mat. The mat was a summer hot spot of CH4 emissions. Fluxes were 1 order of magnitude higher than at an adjacent peatland site. During daytime the pond was a net source of CO2 equivalents to the atmosphere amounting to 0.13 (−0.02 to 1.06) g CO2 equivalents m−2 h−1, whereas the adjacent peatland site acted as a sink of −0.78 (−1.54 to 0.29) g CO2 equivalents m−2 h−1. The photosynthetic CO2 uptake on the floating mat did not counterbalance the high CH4 emissions, which turned the floating mat into a strong net source of 0.21 (−0.11 to 2.12) g CO2 equivalents m−2 h−1. This study highlights the large small-scale variability of CH4 fluxes and CH4 bubble frequency at the peatland–pond interface and the importance of the often large ecotone areas surrounding small ponds as a source of greenhouse gases to the atmosphere.

Hydroclimatic influences on peatland CO2 exchange following upland forest harvesting on the Boreal Plains

AbstractA comparative study of forest clear‐cut logging effects on daily growing season (May to October) net ecosystem CO2 exchange (NEE) of adjacent peatlands was conducted in two neighbouring forest upland‐peatland complexes over 4 years (2005 to 2008) on the Boreal Plains (BP) of Alberta, Canada. Higher vapour pressure deficit at the harvested‐upland (H‐U) peatland, reflecting increased turbulent mixing after adjacent upland forest removal (2007 and 2008), resulted in increased peatland evapotranspiration rates that contributed to a seasonal decline in soil moisture (volumetric moisture content) influencing NEE. Overall, a significant change in mid‐season NEE occurred at the H‐U peatland 1 year post‐harvesting, greater than NEE changes at the neighbouring intact‐upland peatland. However, 2 years post‐harvesting, mid‐season NEE returned to within range of pre‐harvesting variability (−0.54 to 1.34 g CO2‐C m−2 day−1). Results of this study demonstrate that BP peatland NEE is largely regulated by site‐specific water availability, which, in turn, may be influenced in the short term by shifting microclimate and soil moisture patterns because of clear‐cut logging. As such, predicting long‐term carbon storage function of BP peatlands will require careful consideration of changing hydroclimatic conditions because of rapid expansion of BP deforestation, given that these ecosystems already exist in a state of hydrologic risk in this moisture deficit eco‐region. Copyright © 2016 John Wiley &amp; Sons, Ltd.