Boreal Bog Research Articles

Physicochemical Properties of Cattail (Typha) Bioproducts as Substitutes for Commercial Horticultural Growing Media

Peat moss is a primary component of horticultural potting mixes, but its extraction is destructive to boreal bogs and results in considerable greenhouse gas emissions. In this study, we conduct a preliminary investigation into whether a suitable alternative could be produced from Typha domingensis. Cattail harvest offers a means to recycle nutrients from eutrophic wetlands but rarely occurs due to a paucity of economically viable uses. This study investigates Typha-derived bioproducts that could serve as peat substitutes, thus replacing a product that degrades wetlands with one that benefits them. Horticulturally relevant physical characteristics (water holding capacity, dry bulk density, and particle size distribution) and chemical characteristics (nitrogen [N] immobilization, pH, and conductivity) were compared for 3 Typha bioproducts (shredded Typha, Typha compost, and Typha biochar), a blend consisting of equal parts of these bioproducts, and 4 commercially sourced conventional media (peat moss, coco coir, biochar, and compost). For all horticulturally relevant characteristics mentioned, our results for the conventional media were similar to those of previous studies on potting media properties. Typha products showed similar physical characteristics to the commercial media, but chemical characteristics were different and might pose challenges. Nitrogen Drawdown Index (NDI) results showed that shredded Typha immobilized N, making this product less suitable for horticulture. Conductivities exceeding the suggested upper limit for growing media (3.5 dS/m) proved to be the main issue for composted Typha (4.6 dS/m) and Typha biochar (29.1 dS/M), but these defects may be corrected through rinsing and, for Typha biochar, a reduction in pyrolysis temperature. Ultimately, results of this study suggest that, with some refinement in processing to improve chemical characteristics, Typha biochar and Typha compost may have a valuable place in potting mixes. If so, this value-added Typha product would provide a financial incentive to harvest problematic stands of Typha and therefore their constituent nutrients from eutrophic wetlands, helping to mitigate the causes of harmful algal blooms and providing an environmentally friendly alternative to the widespread, destructive practice of mining sphagnum peat moss.

Mosses and vascular plants show diverging diversity patterns along a latitudinal gradient in boreal bogs and fens

AbstractQuestionsThe latitudinal biodiversity gradient; i.e., the increase in biodiversity towards the equator, is one of the most prominent biodiversity patterns. Nevertheless, many questions remain to be answered about the influence of multiple environmental factors on the latitudinal biodiversity gradient, especially for mosses, and the functional diversity of mosses and vascular plants. This study aims at evaluating the influence of latitude, climate, environmental variables, and habitat types (bog vs fen) on taxonomic and functional diversity (α‐diversity and β‐diversity) and the composition of vascular plant and moss species.Location49° N to 55° N in Northwestern Quebec, Canada.TaxonMosses, vascular plants.MethodsWe used a database containing 376 phytosociological plots (400 m2) sampled in boreal peatlands located along a 600‐km latitudinal gradient. We evaluated changes in α‐diversity and β‐diversity in response to latitude, longitude, climate, and local abiotic variables for both taxonomic groups using linear mixed effect models. We evaluated the effects of these variables on taxonomic and functional composition using variance partitioning by redundancy analysis.ResultsMoss diversity increased with latitude, although the effects were masked by environmental variables, whereas vascular plant diversity decreased with latitude in fens and did not vary with latitude in bogs. We observed a decrease in taxonomic and functional uniqueness with latitude. Moss and vascular plant taxonomic and functional composition were primarily structured by contrasting local conditions in bogs and fens, whereas climatic variations along the latitudinal gradient played a secondary role.ConclusionsOur results highlight the contrasting biodiversity patterns in both peatland types and the importance of local habitat conditions in structuring vascular plant and moss diversity. These patterns varied depending on the diversity indicator used, as α‐ and β‐diversity and functional and taxonomic diversity were often decoupled. Future studies should therefore include more than one diversity indicator and consider the differences between ecosystems and taxon groups.

Bog bacterial community: data from north-western Russia.

Wetlands occupy up to 35% of the boreal biome in Russia, according to various estimates. Boreal bogs are global carbon sinks, accounting for more than 65% of the soil carbon stored in the wetland ecosystems of the world. The decomposition of plant residues is one of the most important components of the carbon cycle in wetland systems, while the violation of their fragile balance due to climate change increases the rate of mineralisation of organic matter and releases large amounts of carbon to the atmosphere. The biochemical processes occurring in a peat deposit determine the intensity of the destruction of organic matter and gas exchange. However, the microbial communities of the boreal ombrotrophic bogs, regulating those processes, are poorly studied. Hence, a study of the prokaryote communities of the peat deposits of the southern White Sea coastal ombrotrophic bogs (mostly spread in north-western Russia) was carried out. The taxonomic composition of archaea and bacteria sampled from the deposit's depth of 0-310 cm was studied using high-throughput sequencing of V4 sites of 16S rRNA gene by Illumina technology. As a result, 105 species belonging to 19 phylums were identified. The dominant specific phyla were Pseudomonadota, Acidobacteriota and Verrucomicrobiota, the non-specific phylum being Desulfobacterota. Various groups of methanogenic, methylotrophic and nitrogen-fixing microorganisms were identified. Shannon's biodiversity ranged from 3.5 to 4.6 and ChaO1 - from 232 to 351, decreasing within the depth.

Uranium(VI) interactions with Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I

Pseudomonas sp. are indigenous inhabitants of ombrotrophic bogs which can survive in acidic, nutrient-poor environments with wide temperature fluctuations. Their interactions with contaminant radionuclides can influence radionuclide biogeochemistry in boreal environment. Here, uranium (U(VI)) bioassociation by Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I isolated from a boreal bog was studied by a combination of batch contact experiments, spectroscopy and microscopy. All strains removed U from the solution and the U bioassociation efficiency was affected by the nutrient source, incubation temperature, time and pH. Highest U bioassociation occurred in the strains PS-0-L (0.199 mg U/gBDW) and V4-5-SB (0.223 mg U/gBDW). Based on in-situ attenuated total reflection Fourier transformation infrared spectroscopy (ATR FT-IR) analyses, the most likely functional groups responsible for U binding were the cell surface carboxyl groups. In addition, transmission electron microscopy with energy dispersive X-ray spectroscopy (TEM/EDX) showed dense intra-cellular round- and needle-like U accumulations in the cytoplasm and near to the inner cell membrane. The presence of U with phosphorus was indicated in elemental mapping. Modelled data showed ≡ SOOHx−1 and ≡ SOCO2Hx−1 as the dominant surface sites, contributing to the negative cell surface charge. The U removal efficiency depended on the U(VI) speciation under different pH conditions. At pH 5, the main species reacting with bacterial cell surfaces was UO22+, while at pH 9 UO2(OH)2 and UO2(OH)3- dominated the reactions. Further, U bioassociation increased with increasing aqueous U(VI) concentrations. Our data suggests U bioassociation on 1) outer cell membrane/cell wall associated carboxyl groups (e.g., proteins), and 2) intracellular phosphate groups (e.g., phospholipids).

Sphagnum Litter as the Most Important Genetic Horizon in the Profile of Peat Soils of Boreal Bogs

Sphagnum Litter as the Most Important Genetic Horizon in the Profile of Peat Soils of Boreal Bogs

Sphagnum Litter as the Most Important Genetic Horizon in the Profile of Peat Soils of Boreal Bogs

Peat soils of the taiga zone of West Siberia have historically been relatively poorly studied. In the diagnostics of peat soils, the question of the belonging of the sphagnum litter horizon to the soil profile, as well as the identification of its lower boundary, remains unresolved. In the WRB and Russian Soil Classification, sphagnum litter is considered as a vegetation cover, while in the Soviet classification it is considered as an integral part of the soil profile. The last point of view is also shared by the majority of Russian researchers. Using the material obtained in the study of peat soils in the basin of the river Kazym (subzone of the northern taiga, West Siberia), a comparative characteristic of the sphagnum litter horizon (0–20 cm) and the underlying peat horizon (20–50 cm) was carried out using three parameters: the botanical composition of peat, the degree of peat decomposition, and the color of the soil. All soils are differentiated into the litter horizon and the peat horizon by at least one parameter (5% of the profiles), but in 71% of cases, by three at once. The degree of profile differentiation into two horizons tends to increase in a series of soils formed, respectively, in oligotrophic pine-shrub-sphagnum, oligotrophic complex ridge-hollow, and mesotrophic biogeocenoses. In the overwhelming majority of oligotrophic peat soils, the transition from the litter horizon to the peat horizon is gradual, which does not allow a reproducible assessment of the boundary position in the soil profile. It is proposed to establish a fixed border of the litter horizon at 20 cm from the surface of the bog, referring it to the surface horizon of peat soil.

Field-Layer Vegetation and Water Table Level as a Proxy of CO2 Exchange in the West Siberian Boreal Bog

The Mukhrino field station has participated in the national project on the inventory of carbon fluxes and pools in the terrestrial ecosystems of Russia since 2022. The development of a network of measurements of CO2 fluxes and phytomass covered six types of bog ecosystems typical to Western Siberia. The gross ecosystem exchange (GEE) of the field-layer vegetation (medians for the period from the end of May to the end of July, mgC m−2 h−1; see errors in Results section) decreased in series: Sphagnum bog with sparse low pine trees (“Open bog”), ridges in ridge-hollow patterned bogs (“Ridge”), pine-dwarf shrub-Sphagnum bog (“Tall ryam”), hollows in patterned bogs (“S.hollow”, “E.hollow”) and pine-dwarf shrub-Sphagnum bog (“Ryam”): −220, −200, −125, −120, −109 and −86, respectively. Ecosystem respiration (Reco) here was 106, 106, 182, 55, 97 and 136. The aboveground and belowground phytomass of mosses in this series varied between 368 ± 106–472 ± 184 and 2484 ± 517–6041 ± 2079 g/m2, respectively: the aboveground phytomass of vascular plants and plant litter—15 ± 7–128 ± 95 and 10 ± 6–128 ± 43, respectively. According to the results of mathematical modeling, the best proxy for GEE, in addition to photosynthetically active radiation and soil surface temperature, was the aboveground phytomass of vascular plants (PhV), and for Reco—PhV and the mass of the plant litter of vascular plants.

Long-Term Warming and Nitrogen Addition Regulate Responses of Dark Respiration and Net Photosynthesis in Boreal Bog Plants to Short-Term Increases in CO2 and Temperature

Boreal bog plants adapted to cold and low available nutrient conditions might be strongly affected by global changes, including elevated CO2 (eCO2), warming (W), and increasing nitrogen (N) availability. Here, we examined responses of dark respiration (Rd) and net photosynthesis (Anet) in four dominant bog plants to five levels of short-term increases in both CO2 and temperature (CTI); and the effects of long-term (6 years) W and N addition on these responses. Results indicated that CTI increased Rd; meanwhile, the increase of these environmental variables decreased Anet in all these boreal bog plants. Long-term nitrogen addition simulated the increases of Rd and decreases of Anet in Trichophorum cespitosum. Long-term warming mitigated the increases of Rd in Andromeda glaucophylla and Gaylussacia bigeloviana, and the decrease of Anet in Gaylussacia bigeloviana. These findings highlight the importance of long-term warming and nitrogen addition in regulating responses of boreal bog plants to short-term CTI, suggesting the necessity to investigate the long-term effects of these environmental changes when projecting responses of boreal bog vegetation to global changes.

МОДЕЛЬНО-ЭМПИРИЧЕСКИЙ РАСЧЕТ ПОТОКОВ МЕТАНА И ДИОКСИДА УГЛЕРОДА ИЗ ПОЧВ ТОРФЯНЫХ БОЛОТ

A new process-based model designed to develop a methodology for the inventory of green- house gas emissions from peatbog soils is presented. Within the framework of the general model, a new parameterized formula for calculating methane oxidation in the aerated soil layer and the vegetation layer is proposed. The proposed approach is defined as model-empirical, since the theoretical model relies on the use of values of model parameters determined by a specially developed experimental procedure. A detailed description of the model calibration by means of experimental studies of soil samples is given. Examples of the calculated dependences of methane and carbon dioxide flux densities on the peatbog water level are presented. A comparison with data on methane fluxes measured in boreal bogs demonstrated a satisfactory consistence of the calculated and measured values.

Classification of European bog vegetation of the Oxycocco‐Sphagnetea class

AbstractAimsClassification of European bog vegetation (Oxycocco‐Sphagnetea class); identification of diagnostic species for the class and vegetation subgroups (orders and alliances); development of an expert system for automatic classification of vegetation plots; and production of distribution maps of the Oxycocco‐Sphagnetea class and its alliances.LocationEurope.MethodsA data set of vegetation‐plot records was compiled to include various bog types over most of the European continent. An unsupervised classification (beta‐flexible linkage method, Sørensen distance measure) and detrended correspondence analysis (DCA) ordination were applied. Formal definitions of syntaxa based on species presence and covers, and respecting the results of the unsupervised classification, were developed and included in a classification expert system.ResultsThe Oxycocco‐Sphagnetea class, its two orders (Sphagno‐Ericetalia tetralicis and Sphagnetalia medii) and seven compositionally distinct alliances were formally defined. In addition to the syntaxa included in EuroVegChecklist, three new alliances were distinguished: Rubo chamaemori‐Dicranion elongati (subarctic polygon and palsa mires); Erico mackaianae‐Sphagnion papillosi (blanket bogs of the northwestern Iberian Peninsula); and Sphagno baltici‐Trichophorion cespitosi (boreal bog lawns). The latter alliance is newly described in this article.ConclusionsThis first pan‐European formalized classification of European bog vegetation partially followed the system presented in EuroVegChecklist, but suggested three additional alliances. One covers palsa and polygon mires, one covers Iberian bogs with endemics and one fills the syntaxonomical gap for lawn microhabitats in boreal bogs. A classification expert system has been developed, which allows assignment of vegetation plots to the types described.

Emissions of methane and other biogenic volatile organic compounds from boreal peatlands

This study aims to 1) quantify the spatial and temporal variation in diffusive and ebullitive methane fluxes, and to 2) assess the quantity and quality of BVOC emissions and how they are controlled by vegetation composition and environmental factors in boreal peatlands. Methane fluxes were measured with static chambers and bubble traps from a boreal ombrotrophic bog and compared to eddy covariance measurements on the ecosystem level. BVOC emissions were measured with dynamic chambers from the same boreal bog and a nearby boreal fen. Vegetation removal treatments were applied to differentiate BVOC emissions from intact vegetation, mosses, and peat. Both methane and BVOC emissions showed strong seasonality linked to temperature and vegetation phenology. While diffusive methane fluxes did not differ between three years or different plant community types, methane ebullition was highest during the wettest of the three years studied and varied spatially being greater from open water pools than from wet bare peat surfaces. Decrease in water table led to higher ebullition, but so did also increase in air pressure. In total, ebullition contributed only 2 % – 8 % to the methane emission on the ecosystem level, which supports the general paradigm that diffusion through peat and aerenchymatous plants are the main pathways for methane from peat to the atmosphere. Isoprene was the most emitted BVOC from both peatlands. Isoprene emission was strongly linked to sedges, and thus isoprene and total BVOC emission rates were higher in the sedge-dominated fen than the shrub-dominated bog. Moreover, total BVOC and isoprene emissions were highest from intact vegetation. However, organic halide emissions had stronger link with water level as they were absent during exceptional drought in the summer 2018. Therefore, warming climate and associated drougths and shrubification are likely to alter the quality and quantity of BVOCs emitted from boreal peatlands.

. Productivity changes of wetland and grassland ecosystems along a latitudal gradient

The aim of the study. Analysis of changes in the productivity of dwarf shrub-moss-lichen, pine-dwarf shrub-sphagnum and sedge-sphagnum and grass ecosystems along the latitudinal gradient. Methodology. For a number of bog and grass ecosystems located along a latitudinal gradient from 65 to 50° N in the range of longitudes from 63 to 95° E the stocks of live and dead, aboveground and belowground phytomass, as well as the values of aboveground (ANP), belowground (BNP) and total production (NPP) were analyzed. The data are given for 45 ecosystems grouped into 12 types from forest-tundra mires to desert steppes. The vegetation of ecosystems is represented by bog one (mosses, shrubs and grasses) to the steppe (mesoxerophytic and xerophytic grasses). Since the spread of data on stocks and production for individual ecosystems is large, we present averaged data for ecosystem types. Main results. The largest stock of green phytomass was obtained for floodplain meadows (7 t/ha), the smallest stock was found in the desert steppes (0.8 t/ha). The stock of dead aboveground phytomass was maximal in the fens of the forest-steppe zone (10 t/ha) and minimal in the oligotrophic hollows of boreal bogs (0.3 t/ha). The stock of living belowground organs decreases along a latitudinal gradient from 20 (true steppes) to 3 t/ha (desert steppes), whereas the stock of dead belowground organs decreased from 79 (fens of the forest-steppe zone) to 4 t/ha (in the ryams of the middle taiga and desert steppes). Above-ground production was estimated as highest in the fens of the forest-steppe zone (12), decreasing along the latitudinal gradient down to the desert steppes (1 t/ha per year). Belowground production in all types of ecosystems studied was higher than the above-ground one, ranging from 45 (fens of the forest-steppe zone) to 3 t/ha per year (mires in the forest-tundra). The NPP value in some of the studied ecosystems varied from 57 (fens of the forest-steppe zone) to 5 t/ha per year (mires in the forest-tundra). The BNP/ANP ratio averaged over ecosystem types was maximal in the desert steppes (5.9) and minimal in floodplain meadows (1.9). In the range of latitudes 56-52°N, where steppe meadows, meadow steppes and true steppes located, the NPP, averaged over these ecosystems, varied from 22 to 24 t/ha per year. These ecosystems the most fertile soils of the region, i.e. meadow chernozem and ordinary chernozem (Phaeozems) were developed. To the north and south of this area, the NPP value decreases: to the north due to the lack of heat, and to the south due to lack of moisture. Conclusions. In the biotic cycle in mires differs from that in meadows and steppes by the annual sequestration of a part of the carbon influx in the forming peat. This amount of carbon sequestration is about 10% of the NPP of the wetland ecosystem. In the climax grass ecosystems, the carbon influx is equal to its outflux. These ecosystems are acting as gas exchangers between plants, soil and atmosphere. In contrast to grasslands, wetlands are acting as carbon accumulators that lower the CO2 in the air.

Vegetation composition modulates the interaction of climate warming and elevated nitrogen deposition on nitrous oxide flux in a boreal peatland.

Northern peatlands with large organic nitrogen (N) storage have the potential to be N2 O hotspots under climate warming, elevated N deposition, and vegetation composition change caused by climate change. However, the interactions of these three factors and the primary controls on N2 O fluxes in peatlands are not well-known. Here, the three factors were manipulated in a boreal bog in western Newfoundland, Canada for 5years. We found that warming mitigated the positive N effect on N2 O fluxes in the mid-growing season under intact vegetation owing to the increase of available N uptake by vegetation and less N for N2 O production. In contrast, warming strengthened the N effect on N2 O fluxes in the early growing season under the absence of graminoids or shrubs, which could be attributed to the increase of available carbon and nitrogen for N2 O production. It should be noted that these effects were not observed under the condition of low carbon availability. In addition, gross primary production was found as a critical control on N2 O fluxes under N addition. Our findings emphasize that the interaction of abiotic (warming and elevated nitrogen deposition) and biotic factors (vegetation composition change) on N2 O fluxes should be taken into account in order to project N2 O fluxes in peatland ecosystems accurately.

Steady and ebullitive methane fluxes from active, restored and unrestored horticultural peatlands

Peatlands used for horticultural peat extraction lose their ecological function of carbon accumulation. While their restoration has been shown to increase methane (CH4) flux compared to unrestored sites, the time required for CH4 balance to recover and the factors affecting the recovery remain unclear. We quantified CH4 emissions from restored sites with different time since restoration efforts began (5, 8 and 25 years prior to the study), an unrestored post-extraction (Unrestored) and actively extracted (Active) sites, and compared them to CH4 emission from a natural boreal bog (Natural). All study sites were located within one horticulture peatland complex in central Alberta, Canada. Both steady (diffusive and steady ebullitive) fluxes and abrupt ebullitive events were determined using manual chambers and a portable greenhouse gas analyzer. Methane emissions were greater at the restored sites than at the Natural, Unrestored, and Active sites. Abrupt ebullition occurred only at two restored sites that were flooded/water saturated, dominated by vascular plants, and had the highest steady fluxes. Ebullition accounted for 7% of total CH4 emission at the site restored in 1991 (25–26 years post-restoration), and 6% at the site restored in 2012 (4–5 years post-restoration). Despite shallow water table and dense sedge cover, the third restored site (7–8 years post-restoration), showed no abrupt ebullition and mean steady flux lower than at the Natural site, likely caused by peat geochemistry. At sites where it occurred, ebullition was significantly positively but weakly correlated with CH4 flux, concentration of CH4 in pore water, soil temperature, water table (WT), gross ecosystem production , and percentage cover of moss. Steady CH4 fluxes were higher when soil temperature at 20 cm depth was higher, WT shallow, and with greater plant productivity and cover of graminoids, but lower with higher shrub cover. Peat chemical characteristics can supersede these environmental factors and suppress CH4 emission even in restored, wet, and sedge-dominated sites. Restored sites with more fen-like conditions (wet and sedge-dominated) are likely to have abrupt ebullition events and higher CH4 fluxes than undisturbed bogs, with local controls seemingly more important than time since restoration on resulting CH4 emission.

Ecohydrological controls on apparent rates of peat carbon accumulation in a boreal bog record from the Hudson Bay Lowlands, northern Ontario, Canada

AbstractA multiproxy Holocene record from a bog in the Hudson Bay Lowlands, northern Ontario, Canada, was used to evaluate how ecohydrology relates to carbon accumulation. The study site is located at a somewhat higher elevation and on coarser grained deposits than the surrounding peatlands. This promotes better drainage and thus a slower rate of carbon accumulation relative to sites with similar initiation age. The rate of peat vertical accretion was initially low as the site transitioned from a marsh to a rich fen. These lower rates took place during the warmer temperatures of the Holocene thermal maximum, confirming the importance of hydrological controls limiting peat accretion at the local scale. Testate amoebae, pollen, and plant macrofossils indicate a transition to a poor fen and then a bog during the late Holocene, as the carbon accumulation rate and reconstructed water table depth increased. The bacterial membrane lipid biomarker indices used to infer paleotemperature show a summer temperature bias and appear sensitive to changes in peat type. The bacterial membrane lipid biomarker pH proxy indicates a rich to a poor fen and a subsequent fen to bog transition, which are supported by pollen, macrofossil, and testate amoeba records.

Microbial Community Composition Correlates with Metal Sorption in an Ombrotrophic Boreal Bog: Implications for Radionuclide Retention

Microbial communities throughout the 6.5 m depth profile of a boreal ombrotrophic bog were characterized using amplicon sequencing of archaeal, fungal, and bacterial marker genes. Microbial populations and their relationship to oxic and anoxic batch sorption of radionuclides (using radioactive tracers of I, Se, Cs, Ni, and Ag) and the prevailing metal concentrations in the natural bog was investigated. The majority of the detected archaea belonged to the Crenarchaeota, Halobacterota, and Thermoplasmatota, whereas the fungal communities consisted of Ascomycota, Basidiomycota, and unclassified fungi. The bacterial communities consisted mostly of Acidobacteriota, Proteobacteria, and Chloroflexi. The occurrence of several microbial genera were found to statistically significantly correlate with metal concentrations as well as with Se, Cs, I, and Ag batch sorption data. We suggest that the metal concentrations of peat, gyttja, and clay layers affect the composition of the microbial populations in these nutrient-low conditions and that particularly parts of the bacterial and archaeal communities tolerate high concentrations of potentially toxic metals and may concurrently contribute to the total retention of metals and radionuclides in this ombrotrophic environment. In addition, the varying metal concentrations together with chemical, mineralogical, and physical factors may contribute to the shape of the total archaeal and bacterial populations and most probably shifts the populations for more metal resistant genera.

Linking testate amoeba assemblages to paleohydrology and ecosystem function in Holocene peat records from the Hudson Bay Lowlands, Ontario, Canada

Peat cores from boreal bog and fen sites in the Hudson Bay Lowlands of Northern Ontario, Canada, were analysed to calculate Holocene carbon accumulation rates, and to show how testate amoeba taxonomic assemblages, inferred depths to water table, and four morpho-traits that may be linked to function (mixotrophy, aperture size, aperture position, and biovolume) changed since peatland initiation. Carbon accumulation rates were on average higher for the Holocene in the fen record (19.4 g C m−2 yr−1) in comparison with the bog record (15.7 g C m−2 yr−1), which underwent a fen-to-bog transition around 6900 cal yr BP. Changes in rates of carbon accumulation were most strongly driven by changes in rates of peat vertical accretion, with more rapid rates in the fen record. Carbon accumulation rates were highest following peatland initiation when reconstructed water tables were highest, and in the late Holocene, when water table positions were variable. Taxa with larger biovolumes and apertures were generally more abundant when reconstructed water tables were higher, most notably following peatland initiation. Mixotrophic taxa were more prevalent in drier conditions and in the bog record. Changing frequencies of morpho-traits suggest that testate amoebae may occupy a higher trophic position in the microbial food web during wetter periods, signaling the possibility of internal feedbacks between peatland ecohydrology and critical ecosystem functions including long-term carbon accumulation.

A Comparison of All-Terrain Vehicle (ATV) Trail Impacts on Boreal Habitats Across Scales

ABSTRACT: Recreational trails are an agent of anthropogenic disturbance in nature reserves and other low human impact areas. Effective management must balance the desire of recreationists to use these natural areas with the need to maintain their ecological integrity. Environments with low productivity may be particularly susceptible due to low resistance and resilience to recreational impacts. Our study examined 28 all-terrain vehicle (ATV) trails within the Avalon Wilderness Reserve and the adjacent surrounding area on the island of Newfoundland, Canada. We found that different habitat types (boreal forest, heaths, and bogs) differ in resistance and resilience to both direct on-trail erosion and indirect off-trail vegetation impacts of ATV trails. Dry forested sites were more resistant to direct on-trail erosion but less resistant to indirect off-trail vegetation disturbance. Heath sites were less resistant to direct on-trail erosion but highly resistant to indirect off-trail disturbance. Bog sites had ...

Agricultural drainage increases the photosynthetic capacity of boreal peatlands

A drained boreal bog with active drainage ditches and the introduction of forage grass was compared with a natural bog site to assess the effect of agricultural drainage on the photosynthetic capacity of boreal peatlands. In this study, the net carbon dioxide uptake and the ecosystem respiration were measured using a pair of clear and dark chambers, connected to a greenhouse gas analyzer in order to estimate the gross primary production (GPP). Environmental factors, including photosynthetically active radiation (PAR), peat soil temperature, soil moisture, electrical conductivity and water table depth (WTD), and dissolved organic carbon (DOC) in the soil pore water were also investigated at each site. Our results confirmed a correlation between water table depth, peat soil temperature, electrical conductivity and peatland productivity. Changes in electrical conductivity, water table depth, and peat soil temperature together explained 61% of gross primary productivity variance at our drained peatland pasture site. In general, plant functional types/growth forms did not have any significant difference in their GPP at the drained site except shrubs which had a significantly higher GPP at PAR level greater than 1000 μmol/m2/s (F(3,30.84) = 11.64, p < 0.001). At the natural site, GPP was significantly higher at the hollow (0.168 ± 0.02 mg/m2/s) compared to the hummock (0.098 ± 0.01 mg/m2/s) where relatively the higher WTD was recorded. We therefore concluded that water shortage to the shallow rooting depth of shrubs on our hummock subplots may be the cause of the low productivity. At PAR greater than 1000 μmol/m2/s, productivity at the hollow was still significantly higher (0.17 ± 0.002 mg/m2/s) compared to the hummock (0.10 ± 0.00 mg/m2/s). This suggests that, for ecosystem carbon modelling, the minimum PAR level at which the GPP is estimated is very crucial. All the growth forms at the drained site recorded a significantly higher GPP than the microforms at the natural site. We speculate that not only hydrological changes via agricultural drainage can affect the carbon balance of boreal peatland ecosystem through photosynthesis, but also the hydrological changes in the peat due to the differences in peat soil makeup, structure and density. We, therefore, conclude that differences in microtopography and the corresponding changes in vegetation, land-use practice and its effects on peat soil properties and hydrology should be taken into account when modelling the gross primary production in a peatland ecosystem.

Fine-resolution mapping of microforms of a boreal bog using aerial images and waveform-recording LiDAR

Fine-resolution mapping of microforms of a boreal bog using aerial images and waveform-recording LiDAR