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Sample records for agassiz peatlands northern

  1. Hydrogeologic setting of the Glacial Lake Agassiz Peatlands, northern Minnesota

    USGS Publications Warehouse

    Siegel, Donald I.

    1981-01-01

    Seven test holes drilled in the Glacial Lake Agassiz Peatlands indicate that the thickness of surficial materials along a north-south traverse parallel to Minnesota Highway 72 ranges from 163 feet near Blackduck, Minnesota to 57 feet about 3 miles south of Upper Red Lake. Lenses of sand and gravel occur immediately above bedrock on the Itasca moraine and are interbedded with lake clay and till under the peatlands. Vertical head gradients measured in a piezometer nest near Blackduck on the moraine are downward, indicative of recharge to the regional ground-water-flow system. Vertical head gradients are upward in a piezometer nest on a sand beach ridge in the peatlands 12 miles north of Upper Red Lake. Numerical sectional models indicate that this discharge probably comes from local flow systems recharged from ground-water mounds located under large raised bogs.

  2. Time-series analysis for the episodic production and transport of methane from the Glacial Lake Agassiz peatlands, northern Minnesota. Final report

    SciTech Connect

    Siegel, D.I.

    1998-01-01

    The large peat basins of North America are an important reservoir in the global carbon cycle and a significant source of atmospheric methane. The authors investigated carbon cycling in the Glacial Lake Agassiz peatlands (GLAP) of Minnesota. Initially in 1990, they identified a dramatic change in the concentration of methane in the pore-waters of the raised bogs in the GLAP during an extreme drought. This methane dissipated when the drought broke in 1991 and the occurrence of deep methane is related to changes in the direction of groundwater flow in the peat column. The production of methane and its diffusive loss to the atmosphere was modeled and was about 10 times less than that measured directly in chambers at the land surface. It is clear from the reversals in hydraulic heat, changes in pore-water chemical composition over time, and paleostratigraphic markers, that regional ground water flow systems that are controlled by climate change are unexpectedly a major control over methanogenesis and carbon cycling in GLAP. Seismic profiles made showed that buried bedrock ridges particularly deflect regional groundwater flow upwards towards the land surface and towards raised bog landforms. In addition, high-resolution GPS measurements from data stations funded by this DOE project have shown this year that the peakland land surface elevation changes daily on a scale of cms, and seasonally on a scale of 10s of cm. This most recent observation is exciting because it may reflect episodic degassing of free phase methane from the peat column to the atmosphere, a source for methane previously unaccounted for by methane researchers.

  3. Carbon Cycling in Northern Peatlands

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2010-11-01

    Northern peatlands span only 3 million square kilometers, about 3% of the terrestrial area of the globe, yet they represent a significant terrestrial sink for carbon dioxide. They are also important emitters of methane, an even more potent greenhouse gas. Despite their substantial role in the global carbon cycle, peatlands are not typically incorporated into global climate models. The AGU Monograph Carbon Cycling in Northern Peatlands, edited by Andrew J. Baird, Lisa R. Belyea, Xavier Comas, A. S. Reeve, and Lee D. Slater, looks at the disproportionate role peatlands play in the global carbon budget. In this interview, Eos talks with Andy Baird, University of Leeds, Leeds, United Kingdom.

  4. Heat transport in the Red Lake Bog, Glacial Lake Agassiz Peatlands

    USGS Publications Warehouse

    McKenzie, J.M.; Siegel, D.I.; Rosenberry, D.O.; Glaser, P.H.; Voss, C.I.

    2007-01-01

    We report the results of an investigation on the processes controlling heat transport in peat under a large bog in the Glacial Lake Agassiz Peatlands. For 2 years, starting in July 1998, we recorded temperature at 12 depth intervals from 0 to 400 cm within a vertical peat profile at the crest of the bog at sub-daily intervals. We also recorded air temperature 1 m above the peat surface. We calculate a peat thermal conductivity of 0.5 W m-1 ??C-1 and model vertical heat transport through the peat using the SUTRA model. The model was calibrated to the first year of data, and then evaluated against the second year of collected heat data. The model results suggest that advective pore-water flow is not necessary to transport heat within the peat profile and most of the heat is transferred by thermal conduction alone in these waterlogged soils. In the spring season, a zero-curtain effect controls the transport of heat through shallow depths of the peat. Changes in local climate and the resulting changes in thermal transport still may cause non-linear feedbacks in methane emissions related to the generation of methane deeper within the peat profile as regional temperatures increase. Copyright ?? 2006 John Wiley & Sons, Ltd.

  5. Relationship between subsurface sedimentology and occurrence of vegetation communities of northern Minnesota boreal peatlands

    SciTech Connect

    Stone, M.P.; Siegel, D.I.; Romanowicz, E.A. . Dept. of Geology); Glaser, P.H. )

    1992-01-01

    A recent hydrologic and pore-water chemistry study of the 7,500 km[sup 2] Lake Agassiz Peatlands in northern Minnesota suggest that local groundwater flow through the peat in the Lake Agassiz Peatland is superimposed on a regional flow system. Discharge of the regional flow system into the peasants through the underlying lacustrine sediments controls the occurrence of vegetation communities. These peatlands have distinct vegetation communities; bogs and fens. Bogs have 0.5 to 3 meters relief above adjacent fens are dominated by Picea mariana, Carex oligosperma, and ericaceous shrubs with a continuous mat of Sphagnum moss. Fens are dominated by sedges, such as Carex lasiocarpa and Rhynchospora alba and various Amblystigeaceae mosses. Bogs and fens are hydrologically distinct. It is commonly thought that bogs are isolated from groundwater, receiving most of the water from precipitation, with fens having lateral groundwater flow. The findings indicate that, contrary to common belief, bogs in Lake Agassiz are located over areas of regional groundwater discharge with a shallow local recharging system. However, during droughts the hydrology of bogs change as the regional flow system begins to dominate while the shallow recharging system diminishes. A grain size distribution study of the lacustrine sediments underlying the peat indicate that sediments under bogs are generally coarser than sediments under adjacent fens. Consequently sediments under the bogs have higher hydraulic conductivity than the adjacent fens. The implication of this study is that placement of bogs may be controlled by regional groundwater discharge through areas of high hydraulic conductivity.

  6. Decomposition in northern Minnesota peatlands

    SciTech Connect

    Farrish, K.W.

    1985-01-01

    Decomposition in peatlands was investigated in northern Minnesota. Four sites, an ombrotrophic raised bog, an ombrotrophic perched bog and two groundwater minerotrophic fens, were studied. Decomposition rates of peat and paper were estimated using mass-loss techniques. Environmental and substrate factors that were most likely to be responsible for limiting decomposition were monitored. Laboratory incubation experiments complemented the field work. Mass-loss over one year in one of the bogs, ranged from 11 percent in the upper 10 cm of hummocks to 1 percent at 60 to 100 cm depth in hollows. Regression analysis of the data for that bog predicted no mass-loss below 87 cm. Decomposition estimates on an area basis were 2720 and 6460 km/ha yr for the two bogs; 17,000 and 5900 kg/ha yr for the two fens. Environmental factors found to limit decomposition in these peatlands were reducing/anaerobic conditions below the water table and cool peat temperatures. Substrate factors found to limit decomposition were low pH, high content of resistant organics such as lignin, and shortages of available N and K. Greater groundwater influence was found to favor decomposition through raising the pH and perhaps by introducing limited amounts of dissolved oxygen.

  7. Partitioning Belowground Respiration in a Northern Peatland

    NASA Astrophysics Data System (ADS)

    Stewart, H. E.; Roulet, N. T.; Moore, T.

    2004-05-01

    Although they cover only 3% of the land surface, northern peatlands store up to one-third of the global soil carbon pool, deeming them a significant carbon sink. However, changes in peatland soil respiration could lead to peatlands becoming carbon sources with consequent feedbacks to climate change. In order to understand the global carbon balance we need to understand respiration processes, but compared to photosynthesis we know very little about respiration, especially belowground. Within soils there are three compartments among which carbon is transferred and respired: roots, rhizosphere and root-free soil. In order to further the understanding of respiration processes of northern peatlands, the relative importance of each type of belowground respiration was determined at two locations at Mer Bleue, a northern peatland located near Ottawa, Ontario. Weekly CO2 flux measurements, using dark chambers and a portable IRGA, were made throughout the growing season of 2003. At both areas there are reference plots to determine total respiration where the vegetation remained in tact. Treatment plots were also installed at both areas where foliage was removed in order to determine SOM (shrub-free) respiration. The shrub foliage was replaced with nylon `foliage' in an attempt to maintain soil temperature and moisture conditions. Root respiration was determined by incubating root segments on-site, taking air samples over a one hour period. Rhizosphere respiration was estimated by subtracting SOM, root and aboveground respiration from total respiration, and aboveground respiration was removed from the equation using a calculation from a peatland carbon model.

  8. Mitigating wildfire carbon loss in managed northern peatlands through restoration.

    PubMed

    Granath, Gustaf; Moore, Paul A; Lukenbach, Maxwell C; Waddington, James M

    2016-01-01

    Northern peatlands can emit large amounts of carbon and harmful smoke pollution during a wildfire. Of particular concern are drained and mined peatlands, where management practices destabilize an array of ecohydrological feedbacks, moss traits and peat properties that moderate water and carbon losses in natural peatlands. Our results demonstrate that drained and mined peatlands in Canada and northern Europe can experience catastrophic deep burns (>200 t C ha(-1) emitted) under current weather conditions. Furthermore, climate change will cause greater water losses in these peatlands and subject even deeper peat layers to wildfire combustion. However, the rewetting of drained peatlands and the restoration of mined peatlands can effectively lower the risk of these deep burns, especially if a new peat moss layer successfully establishes and raises peat moisture content. We argue that restoration efforts are a necessary measure to mitigate the risk of carbon loss in managed peatlands under climate change. PMID:27346604

  9. Mitigating wildfire carbon loss in managed northern peatlands through restoration

    PubMed Central

    Granath, Gustaf; Moore, Paul A.; Lukenbach, Maxwell C.; Waddington, James M.

    2016-01-01

    Northern peatlands can emit large amounts of carbon and harmful smoke pollution during a wildfire. Of particular concern are drained and mined peatlands, where management practices destabilize an array of ecohydrological feedbacks, moss traits and peat properties that moderate water and carbon losses in natural peatlands. Our results demonstrate that drained and mined peatlands in Canada and northern Europe can experience catastrophic deep burns (>200 t C ha−1 emitted) under current weather conditions. Furthermore, climate change will cause greater water losses in these peatlands and subject even deeper peat layers to wildfire combustion. However, the rewetting of drained peatlands and the restoration of mined peatlands can effectively lower the risk of these deep burns, especially if a new peat moss layer successfully establishes and raises peat moisture content. We argue that restoration efforts are a necessary measure to mitigate the risk of carbon loss in managed peatlands under climate change. PMID:27346604

  10. Mitigating wildfire carbon loss in managed northern peatlands through restoration

    NASA Astrophysics Data System (ADS)

    Granath, Gustaf; Moore, Paul A.; Lukenbach, Maxwell C.; Waddington, James M.

    2016-06-01

    Northern peatlands can emit large amounts of carbon and harmful smoke pollution during a wildfire. Of particular concern are drained and mined peatlands, where management practices destabilize an array of ecohydrological feedbacks, moss traits and peat properties that moderate water and carbon losses in natural peatlands. Our results demonstrate that drained and mined peatlands in Canada and northern Europe can experience catastrophic deep burns (>200 t C ha‑1 emitted) under current weather conditions. Furthermore, climate change will cause greater water losses in these peatlands and subject even deeper peat layers to wildfire combustion. However, the rewetting of drained peatlands and the restoration of mined peatlands can effectively lower the risk of these deep burns, especially if a new peat moss layer successfully establishes and raises peat moisture content. We argue that restoration efforts are a necessary measure to mitigate the risk of carbon loss in managed peatlands under climate change.

  11. Methane pools within the Glacial Lake Agassiz Peatlands (GLAP) and their response to climatic change.

    NASA Astrophysics Data System (ADS)

    Glaser, P. H.; Chanton, J.; Siegel, D. I.; Reeve, A. S.; Corbett, J. E.; Rosenberry, D. O.

    2014-12-01

    Global warming may destabilize the carbon pool in northern peatlands but it remains uncertain how climatic patterns regulate the transformation of solid-phase peat into greenhouse gases. Here we present a 43-year record of changes in the pore water chemistry from a major peat basin in northern Minnesota. These data indicate that methane production and its transient storage within bogs and fens is finely tuned to climatically driven flow systems on multiple time scales. The peak zones for methanogenesis were apparently limited to the uppermost peat strata during a dry climatic period (1965-1983) when shallow recharge systems prevailed across the GLAP. The shift to a moister climate after 1990 strengthened downward transport systems across the region greatly expanding the vertical suppy of labile root exudates and the peak production zones for methanogenesis in peat profiles. Large methane pools accumulated within the GLAP from 1990 through 2008. Dissolved methane concentrations were 2-to-4 times greater within the deeper peat (1-4 m) than above and were generally higher within bog landforms than in sedge fens. The size of these methane pools varied in response to seasonal and interannual climatic oscillations that apparently affected emission rates via ebullition (from deep peat) and wicking through plant stoma (from the rhizosphere). However, methane pools remained relatively stable during this period, except for a large change between 1990 and 1991. One remaining element of uncertainty concerns the transformation of dissolved methane to free-phase bubbles, which can represent 10-20% of peat volume in the GLAP. Nevertheless, methane profiles from the GLAP indicate that the entire peat profile can function as an incubator for methane depending on the prevailing climate regime and downward transport of labile carbon substrates.

  12. Variability of Carbon Exchanges Between Two Contrasting Northern Peatlands

    NASA Astrophysics Data System (ADS)

    Roulet, N. T.; Nilsson, M.

    2008-12-01

    Northern peatland contain about one quarter of the world's terrestrial carbon. It appears that many peatlands still remains a small, but persistent sinks of carbon dioxide and sources of methane. The sink strength is small compared to actively growing boreal forests but equal to the Holocene average peatland carbon accumulation. This suggests that the function of northern peatlands, with regard to C sequestration, has not change relative to the Holocene average uptake. In contrast to forested ecosystems there have been few long-term continuous measurements of the components of the C balance of peatlands ecosystems. In addition to measurements of net ecosystem exchange and net methane emission (or uptake), the C balance of peatlands requires accurate estimates of the loss of carbon dissolved in runoff. Multi-year measurements of these three major exchanges have been made in contrasting northern peatlands: Mer Bleue, a raised ombrotrophic bog located at the boreal - temperate boundary in eastern Canada, and Degero Stormyr, a mineral poor, oligotrophic fen located in northern Sweden. Despite very different plant communities and moisture regimes the long-term average NEE, methane exchange and net loss of carbon dissolved in water are surprisingly similar in these two systems. However, Mer Bleue has a much greater inter-annual variability in the exchanges than does Degero Stormyr peatland. The difference in exchanges appears related to differences in the variability in moisture supply to the vegetation layer and water storage in the peat. In the early 1990s, the eminent peatland ecologist, Eville Gorham estimated, with few observations, the relative importance of the C balance components of northern peatlands. The multi-year records indicate that these early estimates with reasonable good within an order of magnitude.

  13. Mitigating wildfire carbon loss in managed northern peatlands through restoration

    NASA Astrophysics Data System (ADS)

    Granath, Gustaf; Lukenbach, Max; Moore, Paul; Waddington, James

    2015-04-01

    Wildfire frequency and severity are expected to increase in forested temperate and boreal ecosystems. Recent research indicates that northern peatlands are no exceptions to these risks and may be particularly vulnerable. These ecosystems represent a major component of the global carbon cycle and serve as contemporary and long-term net carbon sink. However, severe, deep burning, fires on these organic soils may not only compromise long-term carbon storage by releasing large amounts of carbon but also impose a real threat to human health and economies through smoke pollution and large costs in fire suppression, respectively. As research in tropical peatlands has revealed, these risks are likely enhanced when northern peatlands are drained and/or mined. Here we examine whether peatland restoration (re-wetting) practices can mitigate the risk of deep burns (>20 cm) and provide management recommendations. We synthesize the effects of drainage on peat moisture content and show how drainage and mining can weaken ecohydrological feedbacks in peatlands, making drained peatlands vulnerable to deep burns and carbon loss. We use bulk density and moisture data from burned, unburned and restored peatlands to evaluate the risk of deep burns under various conditions (differences in peat properties, extent of water table drop) using a new peat smouldering model. Climate change scenarios are shown to explore future risks of deep peat burning in extensively drained areas such as northern Europe. Combining modeling and experimental data we conclude that restoration can successfully lower the risk of deep burns if, for example, a new peat moss layer is established which will ensure a higher moisture content. Considering the large areas of drained and mined peatlands in the northern hemisphere, we will argue that restoration efforts are important to mitigate deep burns and carbon loss in peatlands.

  14. Exploring spatial heterogeneity and resilience in northern peatlands

    NASA Astrophysics Data System (ADS)

    Malhotra, A.; Roulet, N. T.

    2011-12-01

    Northern peatlands cover only 3% of the worlds land area while storing approximately 30% of the world's soil carbon making them important players in the global and regional carbon (C) cycle (Gorham 1991). Current peatland research attempts to predict changes in peatland biogeochemistry given climate change scenarios. However, the focus is primarily on linear responses to changes rather than on self regulation properties that are present in complex systems. Studying peatlands as complex adaptive systems (CAS) is important to fully understand peatland resilience and therefore to better predict response to disturbances. Peatlands possess properties of CAS such as spatial heterogeneity (SH), localized flows, self-organizing structures and non-linearity (Belyea and Baird 2006). The broad hypothesis of our proposed research is that SH in peatlands is positively connected with ecosystem resilience. To address our broad hypothesis we propose to 1) characterize SH in peatlands (using two visible indices of microtopography [MT] and vegetation structure [VEG]), 2) quantify the auto-correlation between visible SH and biogeochemical parameters and 3) investigate short term resilience using the response of biogeochemical parameters to environmental changes. The selection of biogeochemical parameters is based on prevalent theories on the persistence of MT in peatlands and parameters are related to peat accumulation (function of decomposition and net primary production; NPP), hydrology and nutrients (Swanson and Grigal 1988, Belyea and Clymo 2001, Eppinga et al. 2009). Field measurements will be conducted in the Stordalen mire in Abisko, Sweden. This site provides a steep environmental gradient with the presence of 3 peatland types- palsa, bog and fen. Each of these peatland types have varying degrees of spatial heterogeneity, exogenous controls (related to hydrology and permafrost), and therefore hypothesized varying degrees of resilience. Measurements will include nutrients, NPP

  15. Geomorphology and landscape organization of a northern peatland complex

    NASA Astrophysics Data System (ADS)

    Richardson, M. C.

    2012-12-01

    The geomorphic evolution of northern peatlands is governed by complex ecohydrological feedback mechanisms and associated hydro-climatic drivers. For example, prevailing models of bog development (i.e. Ingram's groundwater mounding hypothesis and variants) attempt to explicitly link bog dome characteristics to the regional climate based on analytical and numerical models of lateral groundwater flow and the first-order control of water table position on rates of peat accumulation. In this talk I will present new results from quantitative geomorphic analyses of a northern peatland complex at the De Beers Victor diamond mine site in the Hudson Bay Lowlands of northern Ontario. This work capitalizes on spatially-extensive, high-resolution topographic (LiDAR) data to rigorously test analytical and numerical models of bog dome development in this landscape. The analysis and discussion are then expanded beyond individual bog formations to more broadly consider ecohydrological drivers of landscape organization, with implications for understanding and modeling catchment-scale runoff response. Results show that in this landscape, drainage patterns exhibit relatively well-organized characteristics consistent with observed runoff responses in six gauged research catchments. Interpreted together, the results of these geomorphic and hydrologic analyses help refine our understanding of water balance partitioning among different landcover types within northern peatland complexes. These findings can be used to help guide the development of appropriate numerical model structures for hydrologic prediction in ungauged peatland basins of northern Canada.

  16. Nitrogen dynamics in northern peatland ecosystems

    EPA Science Inventory

    Nitrogen pollution has become a global issue over the last century due to increased fertilizer use and burning of fossil fuels. Excess N has been responsible for algal blooms, hypoxic zones, climate change, and human health issues. Extent of peatlands in the Great Lakes basin is ...

  17. Environmental factors controlling methane emissions from peatlands in northern Minnesota

    NASA Technical Reports Server (NTRS)

    Dise, Nancy B.; Gorham, Eville; Verry, Elon S.

    1993-01-01

    The environmental factors affecting the emission of methane from peatlands were investigated by correlating CH4 emission data for two years, obtained from five different peatland ecosystems in northern Minnesota, with peat temperature, water table position, and degree of peat humification. The relationship obtained between the CH4 flux and these factors was compared to results from a field manipulation experiment in which the water table was artificially raised in three experimental plots within the driest peatland. It was found that peat temperature, water table position, and degree of peat humification explained 91 percent of the variance in log CH4 flux, successfully predicted annual CH4 emission from individual wetlands, and predicted the change in flux due to the water table manipulation. Raising the water table in the bog corrals by an average of 6 cm in autumn 1989 and 10 cm in summer 1990 increased CH4 emission by 2.5 and 2.2 times, respectively.

  18. Investigating dissolved organic matter decomposition in northern peatlands using complimentary analytical techniques

    NASA Astrophysics Data System (ADS)

    Tfaily, Malak M.; Hamdan, Rasha; Corbett, Jane E.; Chanton, Jeffrey P.; Glaser, Paul H.; Cooper, William T.

    2013-07-01

    The chemical transformations that govern storage, degradation, and loss of organic matter in northern peatlands are poorly characterized, despite the significance of these peat deposits as pivotal reservoirs in the global carbon cycle. One of the most challenging problems concerns the character of dissolved organic matter (DOM) in peat porewaters, particularly higher-molecular weight compounds that may function either as non-reactive sinks or reactive intermediates for organic byproducts of microbial decay. The complexity of these large molecules has defied attempts to characterize their molecular structure in bulk samples with a high degree of precision. We therefore determined the composition and reactivity of DOM from representative bog and fen sites in the Glacial Lake Agassiz Peatlands (GLAP) in northern Minnesota, USA. We applied four complementary techniques: electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR MS), proton nuclear magnetic resonance spectroscopy (1H NMR), specific UV absorbance (SUVA) and excitation-emission matrix (EEM) fluorescence spectroscopy. We observed that the vast majority (>80%) of molecular formulas that appear in the surface bog DOM are also present at 2.9 m depth, indicating that much of DOM in the bog is resistant to microbial degradation. In contrast to bog samples, a considerable number of new compounds with low O/C and high H/C elemental ratios were observed in the 3 m fen horizon relative to surface samples. These results indicate a more pronounced difference in the composition of surface and deep DOM in the fen. SUVA, determined at 254 nm, indicated significantly lower aromaticity in deep fen samples relative to deep bog samples. This trend was verified by 1H NMR. Aromatic and carbohydrate components represented up to 70% of deep bog DOM but comprised a much smaller proportion of deep fen DOM, which was dominated by functionalized and non-functionalized aliphatics. Molecular

  19. Microbial Community Structure and Activity Linked to Contrasting Biogeochemical Gradients in Bog and Fen Environments of the Glacial Lake Agassiz Peatland

    PubMed Central

    Lin, X.; Green, S.; Tfaily, M. M.; Prakash, O.; Konstantinidis, K. T.; Corbett, J. E.; Chanton, J. P.; Cooper, W. T.

    2012-01-01

    The abundances, compositions, and activities of microbial communities were investigated at bog and fen sites in the Glacial Lake Agassiz Peatland of northwestern Minnesota. These sites contrast in the reactivity of dissolved organic matter (DOM) and the presence or absence of groundwater inputs. Microbial community composition was characterized using pyrosequencing and clone library construction of phylogenetic marker genes. Microbial distribution patterns were linked to pH, concentrations of dissolved organic carbon and nitrogen, C/N ratios, optical properties of DOM, and activities of laccase and peroxidase enzymes. Both bacterial and archaeal richness and rRNA gene abundance were >2 times higher on average in the fen than in the bog, in agreement with a higher pH, labile DOM content, and enhanced enzyme activities in the fen. Fungi were equivalent to an average of 1.4% of total prokaryotes in gene abundance assayed by quantitative PCR. Results revealed statistically distinct spatial patterns between bacterial and fungal communities. Fungal distribution did not covary with pH and DOM optical properties and was vertically stratified, with a prevalence of Ascomycota and Basidiomycota near the surface and much higher representation of Zygomycota in the subsurface. In contrast, bacterial community composition largely varied between environments, with the bog dominated by Acidobacteria (61% of total sequences), while the Firmicutes (52%) dominated in the fen. Acetoclastic Methanosarcinales showed a much higher relative abundance in the bog, in contrast to the dominance of diverse hydrogenotrophic methanogens in the fen. This is the first quantitative and compositional analysis of three microbial domains in peatlands and demonstrates that the microbial abundance, diversity, and activity parallel with the pronounced differences in environmental variables between bog and fen sites. PMID:22843538

  20. Development of peatlands in northern Minnesota. Final report

    SciTech Connect

    Wright, H.E. Jr.; Glaser, P.H.; Janssens, J.A.

    1985-01-01

    Boreal peatlands are widely distributed across northern Minnesota, where they cover more than 20% of the regional landscape. A regional survey of these peatlands reveals a remarkable degree of uniformity among the vegetation assemblages and an exceptionally close relationship among the vegetation, water chemistry, water level, and presumed hydrology. These relationships are best integrated by the striking landform patterns that, from the air, resemble fluvial landforms such as islands, rivers, and ripple marks. The patterns instead indicate a sensitive adjustment of peat growth to local hydrology and water quality, making the landform patterns an exceptionally important tool for discerning the potential directions and controls on peatland development. A detailed investigation of the Red Lake peatland was undertaken to test a hypothesis on landform development based on an analysis of variations in the present-day landforms, vegetation, water chemistry, and inferred direction of water movement. The peat stratigraphy, based largely on an analysis of fossil bryophytes, indicates that the west-central watershed at Red Lake was overrum by an ombrotrophic bog forest approximately 2000 years ago, but that the forest was subsequently replaced by non-forested Sphagnum communities similar to the vegetation in the present-day bog drains and Sphagnum lawns. These results agree with the initial hypothesis. The stratigraphy indicates that the forested bog islands have expanded over the last 400 years, which indicates a more sensitive adjustment of the patterns to hydrological variations than predicted by the hypothesis. These results may be applicable to a much wider area because of the broad regional uniformity of the peatland patterns. 57 references, 14 figures, 6 tables.

  1. Consolidating and updating estimates of northern peatland extents and carbon stocks

    NASA Astrophysics Data System (ADS)

    Hugelius, G.; Loisel, J.; MacDonald, G. M.; Jackson, R. B.; Treat, C. C.; Turetsky, M. R.; Yu, Z.

    2015-12-01

    Conditions favoring peat accumulation have been particularly prevalent in boreal and subarctic regions. The large pool of organic carbon accumulated in Northern peatlands has been an important component in the global carbon cycle throughout the Holocene. All northern peatlands store an estimated 440 Pg organic carbon while a separate study estimates that permafrost region peatlands store ca. 300 Pg organic carbon. However, the degree of overlap between these studies remains unclear and there are differences in methodologies and definitions which prevent direct harmonization of estimates. Here we address this problems by (1) compiling several different databases of field observation data and by (2) comparing previously estimated northern peatland areal extents to the extents of organic soils estimated from compiled harmonized regional and national soil maps from the northern mid and high latitudes. Organic soils are by definition peatlands with >40 cm of near surface peat. The combined estimated extent of organic soils in these maps is 3.44 million km2. This is very similar to the spatial extents of Northern peatlands derived from various national peat resource inventories as reported by previous studies. Our results show that roughly one third of this organic soil area is in permafrost. Based on newly compiled databases we provide spatially distributed estimates of peatland depth and stocks of peat carbon across different biomes. These analyses reveal significant differences in peat depth and carbon stocks between peatland regions and between non-permafrost and permafrost peatlands.

  2. A new model of long-term, coupled dynamics of carbon and water in northern peatlands

    NASA Astrophysics Data System (ADS)

    Frolking, S.; Roulet, N.

    2008-12-01

    We present a new model that simulates coupled carbon and water dynamics of northern peatlands at an annual time step over time scales of decades to millennia. The Holocene Peatland Model (HPM) simulates peatland carbon and water dynamics as the net consequence of several interacting processes: (1) above- and below-ground vegetation NPP and litter production for bryophytes, woody and herbaceous plants; (2) aerobic and anaerobic litter/peat decomposition down the peat profile; (3) the dependence of peat physical and hydraulic properties on peat composition and degree of humification; and (4) peatland annual water balance, water table depth, and unsaturated zone water content. In this initial analysis, a simulation of long- term peat accumulation is compared against peat core data from a northern peatland in North America. The sensitivity of peatland carbon and water dynamics to climate variability are explored.

  3. The ecology of patterned boreal peatlands of northern Minnesota: A community profile

    SciTech Connect

    Glaser, P.H.

    1987-06-01

    This report reviews the ecological information available for patterned boreal peatlands in northern Minnesota. Although vast areas of Canada and Alaska are covered by boreal forests, they extend southward into the continental United States only in northern Minnesota and to a lesser extent in northern Michigan. In northern Minnesota these peatlands comprise large areas of freshwater wetlands whose unique hydrological characteristics promote the development of patterned vegetation. This publication describes the distribution of peatlands, the physical settings in which they exist, and the processes leading to their development on the landscape. Hydrology, water chemistry, and nutrient cycling in bogs and fens are discussed. The plant communities unique to these types of wetlands, their successional trends, and the animal communities inhabiting them are also described. The profile closes with a summary of past human impacts on peatlands and recommendations for future management.

  4. Predicting methane emission from bryophyte distribution in northern Canadian peatlands

    SciTech Connect

    Bubier, J.L.; Moore, T.R.; Juggins, S.

    1995-04-01

    A predictive model for bryophyte distribution, water table position, and seasonal mean methane (CH{sub 4}) emission was developed for two areas of northern peatland: the Clay Belt of Ontario and the Labrador Trough of Quebec. Water table position and CH{sub 4} flux were the most important environmental variables in canonical correspondence analyses (CCA) of bryophyte data. Water chemistry constituted a second environmental gradient, independent of hydrology and CH{sub 4} flux. Weighted averaging regression and calibration were used to develop a model for predicting log CH{sub 4} flux from bryophyte distribution. The model showed an increase in log CH{sub 4} flux from hummock to carpet and pool species, corresponding with a decrease in height above the mean water table position. The exceptions were rich-fen pool species, which had low CH{sub 4} flux optima in spite of their moisture status. Tolerances were greatest for mid-hummock species and least for carpet and pool species. No overlap in tolerances occurred between hummock and pool species, suggesting that at either end of the height gradient are the best predictors of CH{sub 4} flux. Error analyses showed that bryophytes are equally as effective as water table position for predicting mean CH{sub 4} flux. Bryophytes are distributed in well-defined zones along microtopographic gradients: they integrate long-term changes in the water table, which fluctuates on a daily and seasonal basis along with CH{sub 4} flux, and may be more easily mapped with remote-sensing techniques. Bryophytes, however, are only useful for predicting CH{sub 4} flux within a region; similar species values cannot be extrapolated to other northern peatlands where different climatic and biogeochemical factors may exist. The model may be used in paleoreconstructions of methane emission and for biological monitoring of climate change. 62 refs., 8 figs., 3 tabs.

  5. Simulating long-term carbon and water dynamics in northern peatlands (Invited)

    NASA Astrophysics Data System (ADS)

    Frolking, S. E.; Roulet, N. T.; Quillet, A.; Tuittila, E.; Bubier, J. L.

    2009-12-01

    We present a new model that simulates coupled carbon and water dynamics of northern peatlands at an annual time step over time scales of decades to millennia. The Holocene Peatland Model (HPM) simulates peatland carbon and water dynamics as the net consequence of several interacting processes: (1) above- and below-ground vegetation NPP and litter production for bryophytes and vascular plants; (2) aerobic and anaerobic litter/peat decomposition down the peat profile; (3) the dependence of peat physical and hydraulic properties on peat humification; and (4) peatland annual water balance, water table depth, and unsaturated zone water content. The model generates time series of vegetation, carbon and water dynamics over a 5000-10000 year simulation, and a ‘final state’ peat core that can be compared to contemporary peat core data. The sensitivities of peatland carbon and water dynamics to climate and climate variability and to succession rate are evaluated.

  6. Emissions of methane from northern peatlands: a review of management impacts and future implications

    NASA Astrophysics Data System (ADS)

    Abdalla, Mohamed; Hastings, Astley; Mander, Ulo; Smith, Pete; Nilsson, Mats

    2016-04-01

    Northern peatlands constitute a significant source of atmospheric methane (CH4). However, management of undisturbed peatlands, as well as restoration of disturbed peatlands, will alter the exchange of methane with the atmosphere. The aim of this literature review and meta-analysis was to collate and analyse recent literature to improve our understanding of the impacts of management on CH4 emissions from northern peatlands i.e. latitude 40 to 70o N. Results show that CH4 emissions from natural northern peatlands range from 0 to 154 g C m-2 yr-1 and the overall annual average (mean ± standard deviation) is 11.7 ± 21 g C m-2 yr-1 with the highest emissions from fen ecosystems. Drainage significantly (p<0.05) reduces CH4 emissions to the atmosphere, on average by 84%. However, restoration by rewetting of peatlands and application of N fertilizer both significantly (p<0.05) increase the emissions compared to the original pre-management CH4 fluxes. Methane emissions are mainly controlled by water table (WT) depth, plant community composition and soil pH. Although temperature is not a good predictor of CH4 emissions by itself, the interaction between temperatures, plant community cover, WT depth and soil pH is important. According to short-term forecasts of climate change, these complex interactions will be the main determinant of increased CH4 emissions from northern peatlands. However, to fully evaluate the net effect of management practice on high latitude peatlands both net ecosystem exchange (NEE) and carbon exports needs to be considered.

  7. Representing northern peatland microtopography and hydrology within the Community Land Model

    NASA Astrophysics Data System (ADS)

    Shi, X.; Thornton, P. E.; Ricciuto, D. M.; Hanson, P. J.; Mao, J.; Sebestyen, S. D.; Griffiths, N. A.; Bisht, G.

    2015-11-01

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological dynamics in northern

  8. Representing northern peatland microtopography and hydrology within the Community Land Model

    DOE PAGESBeta

    Shi, Xiaoying; Thornton, Peter E.; Ricciuto, Daniel M.; Hanson, Paul J.; Mao, Jiafu; Sebestyen, Stephen D.; Griffiths, Natalie A.; Bisht, Gautam

    2015-11-12

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to representmore » the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. Furthermore, the new model provides improved predictive capacity for seasonal hydrological

  9. Representing northern peatland microtopography and hydrology within the Community Land Model

    NASA Astrophysics Data System (ADS)

    Shi, X.; Thornton, P. E.; Ricciuto, D. M.; Hanson, P. J.; Mao, J.; Sebestyen, S. D.; Griffiths, N. A.; Bisht, G.

    2015-02-01

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts significant hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological dynamics

  10. Representing northern peatland microtopography and hydrology within the Community Land Model

    SciTech Connect

    Shi, Xiaoying; Thornton, Peter E.; Ricciuto, Daniel M.; Hanson, Paul J.; Mao, Jiafu; Sebestyen, Stephen D.; Griffiths, Natalie A.; Bisht, Gautam

    2015-11-12

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. Furthermore, the new model provides improved predictive capacity for seasonal hydrological dynamics

  11. Representing northern peatland microtopography and hydrology within the Community Land Model

    SciTech Connect

    Shi, X.; Thornton, P. E.; Ricciuto, D. M.; Hanson, P. J.; Mao, J.; Sebestyen, S. D.; Griffiths, N. A.; Bisht, G.

    2015-02-20

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts significant hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological dynamics

  12. Representing northern peatland microtopography and hydrology within the Community Land Model

    DOE PAGESBeta

    Shi, X.; Thornton, P. E.; Ricciuto, D. M.; Hanson, P. J.; Mao, J.; Sebestyen, S. D.; Griffiths, N. A.; Bisht, G.

    2015-02-20

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to representmore » the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts significant hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological

  13. Control of Methane Production and Exchange in Northern Peatlands

    NASA Technical Reports Server (NTRS)

    Crill, Patrick

    1997-01-01

    This proposal has successfully supported studies that have developed unique long ten-n datasets of methane (CH4) emissions and carbon dioxide (CO2) exchange in order to quantify the controls on CH4 production and exchange especially the linkages to the carbon cycle in northern peatlands. The primary research site has been a small fen in southeastern New Hampshire where a unique multi-year data baseline of CH4 flux measurements was begun (with NASA funding) in 1989. The fen has also been instrumented for continuous hydrological and meteorological observations and year-round porewater sampling. Multiyear datasets of methane flux are very valuable and very rare. Datasets using the same sampling techniques at the same sites are the only way to assess the effect of the integrated ecosystem response to climatological variability. The research has had two basic objectives: 1. To quantify the effect of seasonal and interannual variability on CH4flux. 2. To examine process level controls on methane dynamics.

  14. Nitrogen removal in Northern peatlands treating mine wastewaters

    NASA Astrophysics Data System (ADS)

    Palmer, Katharina; Karlsson, Teemu; Turunen, Kaisa; Liisa Räisänen, Marja; Backnäs, Soile

    2015-04-01

    Natural peatlands can be used as passive purification systems for mine wastewaters. These treatment peatlands are well-suited for passive water treatment as they delay the flow of water, and provide a large filtration network with many adsorptive surfaces on plant roots or soil particles. They have been shown to remove efficiently harmful metals and metalloids from mine waters due to variety of chemical, physical and biological processes such as adsorption, precipitation, sedimentation, oxidation and reduction reactions, as well as plant uptake. Many factors affect the removal efficiency such as inflow water quality, wetland hydrology, system pH, redox potential and temperature, the nature of the predominating purification processes, and the presence of other components such as salts. However, less attention has been paid to nitrogen (N) removal in peatlands. Thus, this study aimed to assess the efficiency of N removal and seasonal variation in the removal rate in two treatment peatlands treating mine dewatering waters and process effluent waters. Water sampling from treatment peatland inflow and outflow waters as well as pore waters in peatland were conducted multiple times during 2012-2014. Water samples were analysed for total N, nitrate-N and ammonium-N. Additionally, an YSI EXO2 device was used for continuous nitrate monitoring of waters discharged from treatment peatlands to the recipient river during summer 2014. The results showed that the oxic conditions in upper peat layer and microbial activity in treatment peatlands allowed the efficient oxidation of ammonium-N to nitrite-N and further to nitrate-N during summer time. However, the slow denitrification rate restricts the N removal as not all of the nitrate produced during nitrification is denitrified. In summer time, the removal rate of total N varied between 30-99 % being highest in late summer. N removal was clearly higher for treatment peatland treating process effluent waters than for peatland

  15. Resilience in heterogeneous landscapes: The effect of topography on resilience of carbon uptake in northern peatlands

    NASA Astrophysics Data System (ADS)

    Nijp, Jelmer; Temme, Arnaud; van Voorn, George; Teuling, Ryan; Soons, Merel; Kooistra, Lammert

    2016-04-01

    Northern peatlands contain and store enormous amounts of carbon, and therefore represent an important component of the carbon cycle of the earth. In these wetland ecosystems, the quality of the soil added to the soil surface is determined by the type of peat-forming plants, and affects the carbon accumulated in the peat soil later formed and overall ecosystem functioning. Peatland vegetation is frequently organized in alternating dry hummocks with wet hollows. Such patterned vegetation is associated with different soil carbon accumulation rates, and may develop due to various self-regulating processes originating from ecohydrological feedbacks. Simulation models have shown that vegetation patterning may promote the resilience of peatlands to environmental change (climate, land use), hence maintaining their function as carbon sink. Critically, the results of these model studies rely on the fundamental assumption that environmental conditions are spatially homogeneous. Yet, in real landscape settings, catchment topography has a major impact on water flow and nutrient availability, and is expected to alter vegetation patterning. However, whether, where and how topography affects vegetation patterning in peatlands and associated resilience of ecosystem service provision remains unknown. By combining field observations, remote sensing, and dynamic simulation models (used both as 'sandbox' and 'resilience calculator' for given geomorphological settings), we determine how landscape topography affects ecohydrological processes, vegetation patterning, and associated resilience to environmental change in northern peatlands.

  16. Simulating the sensitivity of northern peatlands to climate change: coupling hydrology and carbon dynamics

    NASA Astrophysics Data System (ADS)

    Roulet, N. T.; Wu, J.

    2009-12-01

    The McGill Wetland Model (MWM) coupled to the Canadian Land Surface Scheme adapted for peat accumulating wetlands (CLASS3w) were used to examine the sensitivity of two types of northern peatlands - ombrotrophic bogs and mineral poor fens, for four different scenarios (A1B, A2, B1 and Commitment) of future climate change based in simulations of the CCCma-GCM. Simulated changes in the components and overall carbon exchanges were considerably different between runs of MWM alone and MWM coupled to CLASS3w indicating the importance of examining peatland biogeochemistry, hydrology and surface climate synergistically rather than as separate components. In all simulations, the carbon sink in the bog and fen decreased, but the fen in the A1B and A2 scenarios flipped from being a sink to a source for atmospheric CO2 by the second half of the 21st century. In these two cases, the source of extra carbon from the mineralization of peat could be as much as a 1 Pg C yr-1 but these simulations also revealed some critical limitations of our approach need addressing before we are prepared to draw broad scale regional or hemispheric conclusions. The two most immediate problems are how to simulate realistically a) the external lateral water inputs to a fen peatland since it can be a critical source of water offsetting reductions in water storage if evapotranspiration increases more than precipitation, and b) changes in peatland vegetation structure with changes in peatlands water storage.

  17. Representing Northern Peatland Hydrology and Biogeochemistry within the Community Land Model

    NASA Astrophysics Data System (ADS)

    Shi, X.; Ricciuto, D. M.; Xu, X.; Thornton, P. E.; Hanson, P. J.; Mao, J.; Sebestyen, S.; Griffiths, N.

    2015-12-01

    Northern peatlands are projected to become very important in future carbon-climate feedback due to their large carbon storage and vulnerability to changes in hydrology and climate impacts. Understanding the hydrology and biogeochemistry is a fundamental task for projecting the fate of massive carbon stores in these systems under future climate change. Models have started to address microtopographic controls on peatland hydrology, but none have considered a prognostic calculation of water table dynamics in vegetated peatlands rather than prescribed regional water tables. We introduced here a new configuration of the Community Land Model (CLM), which includes a fully prognostic water table calculation between hummock and hollow microtopography in a vegetated peatland. We further integrated the hydrology treatment with vertically structured soil organic matter pools, and a newly developed microbial functional group-based methane module. The model was further used to test against observational data obtained within Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) project. Results for water table dynamic, carbon profile, and land surface fluxes of carbon dioxide and methane were reasonable. Model simulations showed that warming and elevated CO2 had significant impacts on land surface fluxes of methane and carbon dioxide. The warming-induced hydrological changes are another factors influencing biogeochemistry along soil profiles and land surface gas fluxes. These preliminary results provide some insights for field experiments as well as data-model comparison in next phase of the SPRUCE project.

  18. Organic Matter Quality and its Influence on Carbon Turnover and Stabilization in Northern Peatlands

    NASA Astrophysics Data System (ADS)

    Turetsky, M. R.; Wieder, R. K.

    2002-12-01

    Peatlands cover 3-5 % of the world's ice-free land area, but store about 33 % of global terrestrial soil carbon. Peat accumulation in northern regions generally is controlled by slow decomposition, which may be limited by cold temperatures and water-logging. Poor organic matter quality also may limit decay, and microbial activity in peatlands likely is regulated by the availability of labile carbon and/or nutrients. Conversely, carbon in recalcitrant soil structures may be chemically protected from microbial decay, particularly in peatlands where carbon can be buried in anaerobic soils. Soil organic matter quality is controlled by plant litter chemical composition and the susceptibility of organic compounds to decomposition through time. There are a number of techniques available for characterizing organic quality, ranging from chemical proximate or elemental analysis to more qualitative methods such as nuclear magenetic resonance, pyrolysis/mass spectroscopy, and Fourier transform infrared spectroscopy. We generally have relied on proximate analysis for quantitative determination of several organic fractions (i.e., water-soluble carbohydrates, soluble nonpolars, water-soluble phenolics, holocellulose, and acid insoluble material). Our approaches to studying organic matter quality in relation to C turnover in peatlands include 1) 14C labelling of peatland vegetation along a latitudinal gradient in North America, allowing us to follow the fate of 14C tracer in belowground organic fractions under varying climates, 2) litter bag studies focusing on the role of individual moss species in litter quality and organic matter decomposition, and 3) laboratory incubations of peat to explore relationships between organic matter quality and decay. These studies suggest that proximate organic fractions vary in lability, but that turnover of organic matter is influenced both by plant species and climate. Across boreal peatlands, measures of soil recalcitrance such as acid

  19. Relationship Between Ecosystem Productivity and Photosynthetically Active Radiation for Northern Peatlands

    NASA Technical Reports Server (NTRS)

    Frolking, S. E.; Bubier, J. L.; Moore, T. R.; Ball, T.; Bellisario, L. M.; Bhardwaj, A.; Carroll, P.; Crill, P. M.; Lafleur, P. M.; McCaughey, J. H.; Roulet, N. T.; Suyker, A. E.; Verma, S. B.; Waddington, J. M.; Whiting, G. J.

    1998-01-01

    We analyzed the relationship between net ecosystem exchange of carbon dioxide (NEE) and irradiance (as photosynthetic photon flux density or PPFD), using published and unpublished data that have been collected during midgrowing season for carbon balance studies at seven peatlands in North America and Europe, NEE measurements included both eddy-correlation tower and clear, static chamber methods, which gave very similar results. Data were analyzed by site, as aggregated data sets by peatland type (bog, poor fen, rich fen, and all fens) and as a single aggregated data set for all peatlands. In all cases, a fit with a rectangular hyperbola (NEE = alpha PPFD P(sub max)/(alpha PPFD + P(sub max) + R) better described the NEE-PPFD relationship than did a linear fit (NEE = beta PPFD + R). Poor and rich fens generally had similar NEE-PPFD relationships, while bogs had lower respiration rates (R = -2.0 micro mol m(exp -2) s(exp -1) for bogs and -2.7 micro mol m(exp -2) s(exp -1)) for fens) and lower NEE at moderate and high light levels (P(sub max)= 5.2 micro mol m(exp -2) s(exp -1) for bogs and 10.8 micro mol m(exp -2) s(exp -1) for fens). As a single class, northern peatlands had much smaller ecosystem respiration (R = -2.4 micro mol m(exp -2) s(exp -1)) and NEE rates (alpha = 0.020 and P(sub max)= 9.2 micro mol m(exp -2) s(exp -1)) than the upland ecosystems (closed canopy forest, grassland, and cropland). Despite this low productivity, northern peatland soil carbon pools are generally 5-50 times larger than upland ecosystems because of slow rates of decomposition caused by litter quality and anaerobic, cold soils.

  20. The hydrology of northern peatlands as affected by biogenic gas: Current developments and research needs

    USGS Publications Warehouse

    Rosenberry, D.O.; Glaser, P.H.; Siegel, D.I.

    2006-01-01

    Recent research indicates that accumulation and release of biogenic gas from northern peatlands may substantially affect future climate. Sudden release of free-phase gas bubbles into the atmosphere may preclude the conversion of methane to carbon dioxide in the uppermost oxic layer of the peat, resulting in greater contribution of methane to the atmosphere than is currently estimated. The hydrology of these peatlands also affects and is affected by this process, especially when gas is released suddenly and episodically. Indirect hydrological evidence indicates that ebullitive gas releases are relatively frequent in some peatlands and time-averaged rates may be significantly greater than diffusive releases. Estimates of free-phase gas contained in peat have ranged from 0 to nearly 20% of the peat volume. Abrupt changes in the volume of gas may alter hydraulic gradients and movement of water and solutes in peat, which in turn could alter composition and fluxes of the gas. Peat surfaces also move vertically and horizontally in response to accumulation and release of free-phase gas. Future research should address the distribution, temporal variability, and relative significance of ebullition in peatlands and the consequent hydrological responses to these gas-emission events. Copyright ?? 2006 John Wiley & Sons, Ltd.

  1. Holocene Carbon Accumulation and Soil Properties in Northern Peatlands: A Circum-Arctic Synthesis (Invited)

    NASA Astrophysics Data System (ADS)

    Loisel, J.; Beilman, D.; Yu, Z.; Camill, P.

    2013-12-01

    Of all terrestrial ecosystems, peatlands are arguably the most efficient at sequestering carbon (C) over long time scales. However, ongoing and projected climate change could shift the balance between peat production and organic matter decomposition, potentially impacting the peatland C-sink capacity and modifying peat-C fluxes to the atmosphere. Yet, the sign and magnitude of the peatland carbon-climate feedback remain uncertain and difficult to assess because of (1) limited understanding of peatland responses to climate change, (2) data gaps and large uncertainties in regional peatland C stocks, and (3) non-linear peatland responses to external forcing. Here we present results from a comprehensive compilation of peat soil properties and Holocene C data for northern peatlands. Our compiled database consists of >250 peat cores from > 200 sites located north of 45N. This synthesis is novel in that our C accumulation estimates are based on directly measured bulk density and C content values. It also encompasses regions within which peat-C data have only recently become available, such as the West Siberia Lowlands, Hudson Bay Lowlands and Kamchatka. Our averaged bulk density value of 0.13 g cm-3 (n = 17,319) is about 16% higher than Gorham's (1991, Ecol. Appl.) widely used estimate of 0.112 g cm-3 for northern peatlands, and 30% larger than the generic value of 0.10 g cm-3 used in recent synthesis (Yu et al. 2009, AGU Monograph 184). When combined with our mean C content value of 48% (n = 2431), these differences in bulk density have important implications for estimating the total C stocks in northern peatlands. Soil organic carbon density (SOC) ranged from 12 to 334 kg C m-2, with a mean value of 102 kg C m-2. A regression model revealed a significant, positive correlation between peat depths and SOC (R2 = 0.675, p < 0.0001), such that higher SOC densities characterized deeper sites. Comparing these values with those published in soil-C surveys that only account for

  2. Postglacial Spatiotemporal Peatland Initiation and Lateral Expansion Dynamics in North America and Northern Europe: Implications to Carbon Uptake

    NASA Astrophysics Data System (ADS)

    Korhola, Atte; Ruppel, Meri; Virtanen, Tarmo; Väliranta, Minna

    2016-04-01

    Peatlands are major ecosystems of the Northern Hemisphere and have a significant role in global biogeochemical processes. Consequently, there is growing interest in understanding past, present and future peatland dynamics. However, chronological and geographical data on peatland initiation are scattered, impeding the reliable establishment of postglacial spatiotemporal peatland formation patterns and their possible connection to climate. In order to present a comprehensive account of postglacial peatland formation histories in North America and northern Europe, we collected a data set of 1400 basal peat ages accompanied by below-peat sediment-type interpretations from literature. Our data indicate that all peatland initiation processes (i.e. primary mire formation, terrestrialization and paludification) co-occurred throughout North America and northern Europe during the Holocene, and almost equal amounts of peatlands formed via these three processes. Furthermore, the data suggest that the processes exhibited some spatiotemporal patterns. On both continents, primary mire formation seems to occur first, soon followed by terrestrialization and later paludification. Primary mire formation appears mostly restricted to coastal areas, whereas terrestrialization and paludification were more evenly distributed across the continents. Primary mire formation seems mainly connected with physical processes, such as ice sheet retreat. Terrestrialization probably reflected progressive infilling of water bodies on longer timescales but was presumably drought driven on shorter timescales. Paludification seems affected by climate as it slowed down in Europe during the driest phase of the Holocene between 6 and 5 ka. Lateral expansion of existing peatlands accelerated c. 5000 years ago on both continents, which was likely connected to an increase in relative moisture.

  3. Impact of mine wastewaters on greenhouse gas emissions from northern peatlands used for mine water treatment

    NASA Astrophysics Data System (ADS)

    Palmer, Katharina; Ronkanen, Anna-Kaisa; Klöve, Björn; Hynynen, Jenna; Maljanen, Marja

    2015-04-01

    increasing distances from the ditch. NO3- concentrations were lower in pore water than in surface water, and the peak in NO3- concentration shifted further away from the distribution ditch with increasing depth. On the contrary, NH4+ concentrations were generally higher in pore water than in surface water, and peak concentrations increased with increasing depth. Highest NH4+ concentrations were detected in 30 to 60 cm depth near the outlet at the south end of TP 4. Fluxes of the greenhouse gases CH4 and N2O from 4 sampling points (2 from TP 4, 1 from TP 1, 1 from reference area) were measured on 7 different occasions 2013 and 2014. CH4 emissions were in the same range as measured in other northern pristine peatlands in the reference area, which is not influenced by mine wastewaters. Treatment peatlands showed only very minor CH4 emissions or even CH4 uptake. On the other hand, treatment peatlands showed high N2O emissions, which were in the same range as N2O emissions observed from northern peat soils used for agriculture. Highest emissions were generally observed near the wastewater distribution ditch of TP 4. N2O emissions from the reference area were negligible or even negative. NO3-, NH4+ and SO42- concentrations were determined from surface waters from each sampling point and sampling occasion. N2O emissions were positively correlated with NO3- concentrations, indicating denitrification-derived N2O production in treatment peatlands. On the other hand, CH4 emissions were negatively correlated with SO42- and NO3- concentrations, indicating that the presence of alternative electron acceptors in large amounts suppresses CH4 production in treatment peatlands. In conclusion, the study revealed that (i) treatment peatlands receive high loads of NO3-, NH4+ and SO42- which are not well retained in the peatlands, (ii) mine wastewaters positively and negatively affect N2O and CH4 emissions, respectively, (iii) N2O emissions are positively correlated with NO3- concentrations, and

  4. Can frequent precipitation moderate drought impact on peatmoss carbon uptake in northern peatlands?

    NASA Astrophysics Data System (ADS)

    Nijp, Jelmer; Limpens, Juul; Metselaar, Klaas; van der Zee, Sjoerd; Berendse, Frank; Robroek, Bjorn

    2014-05-01

    Northern peatlands represent one of the largest global carbon stores that can potentially be released by water table drawdown during extreme summer droughts. Small precipitation events may moderate negative impacts of deep water levels on carbon uptake by sustaining photosynthesis of peatmoss (Sphagnum spp.), the key species in these ecosystems. We experimentally assessed the importance of the temporal distribution of precipitation for Sphagnum water supply and carbon uptake during a stepwise decrease in water levels in a growth chamber. CO2 exchange and the water balance were measured for intact cores of three peatmoss species representative of three contrasting habitats in northern peatlands (Sphagnum fuscum, S. balticum and S. majus). For shallow water levels, capillary rise was the most important source of water for peatmoss photosynthesis and precipitation did not promote carbon uptake irrespective of peatmoss species. For deep water levels, however, precipitation dominated over capillary rise and moderated adverse effects of drought on carbon uptake by peat mosses. The ability to use the transient water supply by precipitation was species-specific: carbon uptake of S. fuscum increased linearly with precipitation frequency for deep water levels, whereas S. balticum and S. majus showed depressed carbon uptake at intermediate precipitation frequencies. Our results highlight the importance of precipitation for carbon uptake by peatmosses. The potential of precipitation to moderate drought impact, however, is species specific and depends on the temporal distribution of precipitation and water level. These results also suggest that modelling approaches in which water level depth is used as the only state variable determining water availability in the living moss layer and (in)directly linked to Sphagnum carbon uptake may have serious drawbacks. The predictive power of peatland ecosystem models may be reduced when deep water levels prevail, as precipitation

  5. Trace gas responses in a climate change experiment in northern peatlands

    SciTech Connect

    Bridgham, S.D.; Pastor, J.; Updegraff, K.

    1995-09-01

    We established 54 mesocosms of 2.2 m{sup 2} and approximately 0.6 m depth with intact vegetation communities, with half originating from a poor-intermediate fen and half from a bog in northern Minnesota. The mesocosms were subjected to a series of water-table (0,-10,-20 cm) and heating treatments, with the heating treatments from overhead infrared lamps (full on, half on, ambient). Heating began in late summer 1994, and gas flux measurements were taken until the onset of winter. The first year results indicate peatland type and water-table treatment had highly significant effects on CH{sub 4} emissions, while the effect of heating treatment was weaker (P=0.07). Overall CH{sub 4} fluxes were higher in bog than in fen mesocosms. Despite the significant treatment effects, a multiple regression with water-table depth and soil temperature as the independent variables only predicted 14% and 34% of the variation in CH{sub 4} flux in the bog and fen mesocosms, respectively. CO{sub 2} emissions (net ecosystem respiration) were significantly affected by peatland type (higher in bogs) and heat treatment, but not but by water-table treatment. Soil temperature predicted 34% and 48% of the CO{sub 2} flux in the bog and fen mesocosms, respectively. These preliminary results indicate that climate change will have a significant impact on trace gas emissions in northern peatlands, but that much of the variability in emission cannot be explained by environmental correlates, even under carefully controlled conditions.

  6. Surface deformations as indicators of deep ebullition fluxes in a large northern peatland

    USGS Publications Warehouse

    Glaser, P.H.; Chanton, J.P.; Morin, P.; Rosenberry, D.O.; Siegel, D.I.; Ruud, O.; Chasar, L.I.; Reeve, A.S.

    2004-01-01

    Peatlands deform elastically during precipitation cycles by small (??3 cm) oscillations in surface elevation. In contrast, we used a Global Positioning System network to measure larger oscillations that exceeded 20 cm over periods of 4-12 hours during two seasonal droughts at a bog and fen site in northern Minnesota. The second summer drought also triggered 19 depressuring cycles in an overpressured stratum under the bog site. The synchronicity between the largest surface deformations and the depressuring cycles indicates that both phenomena are produced by the episodic release of large volumes of gas from deep semi-elastic compartments confined by dense wood layers. We calculate that the three largest surface deformations were associated with the release of 136 g CH4 m-2, which exceeds by an order of magnitude the annual average chamber fluxes measured at this site. Ebullition of gas from the deep peat may therefore be a large and previously unrecognized source of radiocarbon depleted methane emissions from northern peatlands. Copyright 2004 by the American Geophysical Union.

  7. PEATBOG: a biogeochemical model for analyzing coupled carbon and nitrogen dynamics in northern peatlands

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Blodau, C.

    2013-08-01

    Elevated nitrogen deposition and climate change alter the vegetation communities and carbon (C) and nitrogen (N) cycling in peatlands. To address this issue we developed a new process-oriented biogeochemical model (PEATBOG) for analyzing coupled carbon and nitrogen dynamics in northern peatlands. The model consists of four submodels, which simulate: (1) daily water table depth and depth profiles of soil moisture, temperature and oxygen levels; (2) competition among three plants functional types (PFTs), production and litter production of plants; (3) decomposition of peat; and (4) production, consumption, diffusion and export of dissolved C and N species in soil water. The model is novel in the integration of the C and N cycles, the explicit spatial resolution belowground, the consistent conceptualization of movement of water and solutes, the incorporation of stoichiometric controls on elemental fluxes and a consistent conceptualization of C and N reactivity in vegetation and soil organic matter. The model was evaluated for the Mer Bleue Bog, near Ottawa, Ontario, with regards to simulation of soil moisture and temperature and the most important processes in the C and N cycles. Model sensitivity was tested for nitrogen input, precipitation, and temperature, and the choices of the most uncertain parameters were justified. A simulation of nitrogen deposition over 40 yr demonstrates the advantages of the PEATBOG model in tracking biogeochemical effects and vegetation change in the ecosystem.

  8. PEATBOG: a biogeochemical model for analyzing coupled carbon and nitrogen dynamics in northern peatlands

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Blodau, C.

    2013-03-01

    Elevated nitrogen deposition and climate change alter the vegetation communities and carbon (C) and nitrogen (N) cycling in peatlands. To address this issue we developed a new process-oriented biogeochemical model (PEATBOG) for analyzing coupled carbon and nitrogen dynamics in northern peatlands. The model consists of four submodels, which simulate: (1) daily water table depth and depth profiles of soil moisture, temperature and oxygen levels; (2) competition among three plants functional types (PFTs), production and litter production of plants; (3) decomposition of peat; and (4) production, consumption, diffusion and export of dissolved C and N species in soil water. The model is novel in the integration of the C and N cycles, the explicit spatial resolution belowground, the consistent conceptualization of movement of water and solutes, the incorporation of stoichiometric controls on elemental fluxes and a consistent conceptualization of C and N reactivity in vegetation and soil organic matter. The model was evaluated for the Mer Bleue Bog, near Ottawa, Ontario, with regards to simulation of soil moisture and temperature and the most important processes in the C and N cycles. Model sensitivity was tested for nitrogen input, precipitation, and temperature, and the choices of the most uncertain parameters were justified. A simulation of nitrogen deposition over 40 yr demonstrates the advantages of the PEATBOG model in tracking biogeochemical effects and vegetation change in the ecosystem.

  9. Long-term monitoring of permafrost change in a palsa peatland in northern Quebec, Canada: 1983-1993

    SciTech Connect

    Laberge, M.J.; Payette, S.

    1995-05-01

    Changes in the spatial distribution of permafrost in the Ouiatchouane palsa peatland (northern Quebec) were monitored from 1957 to present, using aerial photographs taken in 1957 (starting date) and three field surveys in 1973, 1983, and 1993, respectively. Between 1983 and 1993, palsa degradation occurred at about the same rate as between 1957 and 1983, although minor differences in rate of permafrost decay during the three periods (1957-1973, 1973-1983, 1983-1993) may be attributed in part to misidentification of marginal permafrost landforms. Permafrost degradation appeared to be influenced by height of individual palsas and their location within the peatland. Since 1983, thermokarst ponds have been progressively invaded by sedges and Sphagnum, a situation promoting successional peatland development and palsa formation as suggested by the presence of a small incipient palsa. Although the main geomorphic process at work is palsa degradation, permafrost aggradation is possible under present climatic conditions. 28 refs., 3 figs., 1 tab.

  10. Northern Peatland Shifts Under Changing Climate and Their Impact on Permafrost

    NASA Astrophysics Data System (ADS)

    Shur, Y.; Jorgenson, T.; Kanevskiy, M. Z.

    2014-12-01

    Formation of peatlands depends primarily on climate and its interactions with hydrology, soil thermal regimes, plant composition, and nutrients. A water balance with precipitation exceeding evaporation is necessary for their formation. The rate of peat accumulation also greatly depends on thermal resources. The prominent impact of the water balance and temperature on peatland formation is evident in the West Siberia Lowland. The rate of peat accumulation steadily increases from arctic tundra to moss tundra, to forest tundra, to northern taiga, and to southern taiga. This increase is a result in increase in air temperature and length of the growing season because all of these zones have water balance favorable for peat formation. Further to south, evaporation prevails over precipitation and peat formation occurs only in isolated areas. Climate change will redefine geographical distribution of climatic and vegetation zones. It is predicted that in arctic and subarctic regions the difference between precipitation and evaporation will increase and as a result these regions will remain favorable to peat accumulation. With increase of thermal resources, the rate of peat accumulation will also increase. The Alaska Arctic Coastal Plain is of a special interest because it has thousands of shallow lakes, which due to warming climate would shift from open waterbodies to peatlands through shoreline paludification and infilling. The accumulation of organic matter will likely turn open water into shore fens and bogs, and eventually to peat plateaus, as is occurring in many boreal landscapes. Expected impact on permafrost in arctic and subarctic regions will include rise of the permafrost table, thickening of the ice-rich intermediate layer with ataxitic (suspended) cryostructure, and replacement of frost boils with earth hummocks. In the contemporary continuous permafrost zone, permafrost formed as climate-driven will be transformed into climate-driven ecosystem protected

  11. Free phase gas processes in a northern peatland inferred from autonomous field-scale resistivity imaging

    NASA Astrophysics Data System (ADS)

    Terry, Neil; Slater, Lee; Comas, Xavier; Reeve, Andrew S.; Schäfer, Karina V. R.; Yu, Zhongjie

    2016-04-01

    The mechanisms that control free phase gas (FPG) dynamics within peatlands, and therefore estimates of past, present, and future gas fluxes to the atmosphere remain unclear. Electrical resistivity imaging (ERI) is capable of autonomously collecting three-dimensional data on the centimeter to tens of meter scale and thus provides a unique opportunity to observe FPG dynamics in situ. We collected 127 3-D ERI data sets as well as water level, soil temperature, atmospheric pressure, and limited methane flux data at a site in a northern peatland over the period July-August 2013 to improve the understanding of mechanisms controlling gas releases at a hitherto uncaptured field scale. Our results show the ability of ERI to image the spatial distribution of gas accumulation and infer dynamics of gas migration through the peat column at high (i.e., hourly) temporal resolution. Furthermore, the method provides insights into the role of certain mechanisms previously associated with the triggering of FPG releases such as drops in atmospheric pressure. During these events, buoyancy-driven gas release primarily occurs in shallow peat as proposed by the "shallow peat model." Releases from the deeper peat are impeded by confining layers, and we observed a large loss of FPG in deep peat that may likely represent a rupture event, where accumulated FPG escaped the confining layer as suggested by the "deep peat model." Negative linear correlations between water table elevation and resistivity result from hydrostatic pressure regulating bubble volume, although these variations did not appear to trigger FPG transfer or release.

  12. Radiocarbon evidence for the substrates supporting methane formation within northern Minnesota peatlands

    SciTech Connect

    Chanton, J.P.; Bauer, J.E.; Glaser, P.A.

    1995-09-01

    Bogs and fens from northern Minnesota produce large quantities of CH{sub 4}, which may be either emitted to the atmosphere or stored in below-ground reservoirs. The identity of the organic materials that support CH{sub 4} production has been uncertain, but we present evidence that a significant fraction of surface emission and below-ground CH{sub 4} is derived from recently fixed organic compounds. First, the CH{sub 4} emitted from both bogs and fens has a {sup 14}C signature equivalent to contemporary values for atmospheric CO{sub 2}. Second, in flooded fens rates of CH{sub 4} emission are linearly related to rates of CO{sub 2} exchange to the {delta}{sup 13}C of emitted CH{sub 4}. Third, peat-porewaters as deep as several meters below the surface contain mixtures of CH{sub 4} derived from both modern and older organic substrates. The source of the modern organic substrates is most likely dissolved organic compounds produced from the decay of recently produced litter, roots and root exudation products and transported into deeper layers of the peat. These data indicate that CH{sub 4} emissions are closely linked to the living vegetation and hydrology of northern peatlands and less dependent on the lability and decomposition of peat within the deeper layers of the catotelm.

  13. Estimating Effects of Atmospheric Deposition and Peat Decomposition Processes on Mercury and Sulfur Accumulation and Retention in Northern Peatlands, Minnesota

    NASA Astrophysics Data System (ADS)

    Furman, O.; Nater, E.; Toner, B. M.; Sebestyen, S. D.; Tfaily, M. M.; Chanton, J.; Kolka, R. K.

    2013-12-01

    Northern peatland ecosystems play an important role in mercury (Hg) and sulfur (S) co-cycling. Peatlands are sinks for total Hg and sources for methyl Hg through the activity of sulfate-reducing bacteria. These ecosystems are vulnerable to environmental change, and projected changes in climate for the north-central U.S. have the potential to affect Hg and S stores and cycling in the subsurface, which may stimulate the release of bioaccumulative methyl Hg to receiving water bodies. SPRUCE (Spruce and Peatland Responses under Climate and Environmental change experiment) is an interdisciplinary study of the effects of temperature and enriched carbon dioxide on the responses of northern peatland ecosystems at the Marcell Experimental Forest, Minnesota. In the first year of SPRUCE, we are investigating Hg and S accumulation rates in 12-m diameter experimental plots on a black spruce bog before peatland heating experiments start in 2014. Understanding Hg and S accumulation rates and their retention mechanisms in the subsurface are needed in order to reconstruct historical trends in Hg and S deposition, and predict peatland responses to climate change. In this study, we will attempt to separate the effects of atmospheric deposition vs peat humification on Hg and S retention. As such, peat cores were sampled from sixteen experimental SPRUCE plots in August 2012. These 'Time 0' peat subsamples have been analyzed for total Hg, methyl Hg and total S, and bulk density as a function of depth (<2 m). In addition, peat subsamples have been analyzed for 14C and 13C to determine the age of peat and derive peat, Hg and S accumulation rates. Our preliminary results indicate that both total and methyl Hg, and total S concentrations reached the peak value in the 20-40 cm peat section, which is the transition zone between transiently oxidized acrotelm and permanently saturated anaerobic catotelm. Total and methyl Hg concentrations were several times lower in deeper profiles (>50 cm

  14. Past and Future Stability of Deep Peatland Carbon Stocks: Assessing the Nature and Fate of Carbon in a Northern Minnesota Ombrotrophic Peatland (Invited)

    NASA Astrophysics Data System (ADS)

    Hanson, P. J.; Chanton, J.; Iversen, C. M.; McFarlane, K. J.; Tfaily, M. M.; Xu, X.

    2013-12-01

    An ombrotrophic Picea-Sphagnum peatland located on the Marcell Experimental Forest in northern Minnesota is being prepared for experimental manipulations to evaluate carbon cycle responses to warming and elevated CO2. Pretreatment characterization of the peatland, which has a mean peat depth of ~3 meters, showed that belowground carbon (C) stocks were greater than 2200 MgC ha-1. This is easily 10× greater than the combined above- and belowground C stocks found in typical eastern deciduous forests. Carbon has accumulated under saturated, cool to cold conditions since the last glaciers receded some 10,000 years ago. Mean bulk-14C assessments show a modern C signature and decadal turnover time for peat in the raised hummock topography, as well as in the oxic acrotelm layer which extends to a depth of 30-cm below hollow microtopography. Deeper peat layers (below 30-cm depth) have C ages ranging from 1000- to 2000 years for relatively shallow layers, to between 7000 and 8000 years at 2.5 m depth. In contrast, the 14C signatures of dissolved inorganic C (DIC) and dissolved organic C (DOC), which reflect the substrates consumed by microbes, were relatively modern, even at depths of up to 2 meters. The modern 14C signatures indicate that microbial respiration at depth is fueled by surface inputs of DOC. Furthermore, the contrast in δ14C between solid-phase peat and DOC at deeper peat depths will allow researchers to quantify the effects of warming and elevated CO2 on the fate of peat stored in this ombrotrophic peatland for millennia. It is unclear whether C accumulation in peatlands will continue under warmer conditions associated with atmospheric and climatic change. Modeled projections for net peat C turnover throughout the peat profile will be discussed in the context of the planned warming manipulations. Initial hypotheses suggest that peat accumulation may be sustained for low levels of warming, but shift to a pattern of net carbon release as both CO2 and CH4 for

  15. Decadal Vegetation Changes in a Northern Peatland,Greenhouse gas Fluxes and net Radiative Forcing

    NASA Astrophysics Data System (ADS)

    Johansson, T.; Malmer, N.; Christensen, T. R.; Kerman, H. J.

    2004-05-01

    Today the sub-Arctic permafrost thaws with an accelerating rate. This has implications for the stability of the northern peatland ecosystems that are underlain by permafrost and eventually for the energy balance of the Earth. These ecosystems are unique in the world; while at the same time considered to have been net carbon sinks since the last glacial termination they have the ability to release large amounts of methane. During the last 30 years the vegetation of northernmost Swedish peatlands have undergone change. Dry ombrotrophic systems have become wet and nutrient rich reflecting the close connection between vegetation and permafrost status. The objective of this study was to analyse how the vegetation change since 1970 on Stordalen mire (a mixed mire complex in northern Sweden, 68° 20' N, 19\\deg02' E) may have changed the net exchange of greenhouse gases CO2 and CH4. Color infrared aerial images (CIR) of the entire mire from 1970 and 2000 were used. We estimated the large-scale vegetation change on the Stordalen mire, and used available and published data on plot scale C-fluxes to calculate exchanges in total C- equivalents (C-CO2 and C-CH4). These were then scaled to the whole mire to estimate the effect vegetation change has had on the radiative forcing of the entire mire. The derived vegetation maps of the central part of Stordalen mire (15 ha) clearly show a decadal change in vegetation composition between 1970-2000. The areal extension of dry elevated ombrotrophic areas has decreased by 11- 36% or expressed in hectares, an approximate loss of 1 to 3 hectares. Accordingly dwarf shrub vegetation with a high abundance of bare peat and lichens in the bottom layer and associated species in the field layer are nowadays less abundant on the mire. During the same time period the total CO2 and CH4 flux changed by 1- 11% (sink) and 19- 66% (source) respectively. When calculating the flux as total C-equivalents, using IPCC's GWP (Global Warming Potentials) for

  16. Non-invasive Investigation of Free Phase Gas Accumulation in a Northern Peatland Using GPR: Vegetation Effects

    NASA Astrophysics Data System (ADS)

    Parsekian, A.; Nolan, J.; Comas, X.; Slater, L.

    2008-05-01

    Northern peatlands are known to produce methane, although the contribution of this source to the atmospheric methane burden is still uncertain. Biogenic methane releases have become an increasingly important issue with regard to assessing the impact of northern peatlands impact on the global carbon budget. Previous workers have suggested that methane production is pronounced in a zone a few meters below the surface and that accumulation of free phase gas is encouraged by the presence of confining layers that act to hinder FPG release. We used ground penetrating radar (GPR) to non-invasively investigate (1) where free-phase gas (FPG) methane may be accumulating vertically within the peat column of a northern peatland, and (2) the dependence of methane production on vegetation type. Common mid-point (CMP) measurements were applied to investigate the likely vertical spatial distribution/ concentration of trapped methane within the peat profile within different vegetation units. The CMP data were modeled using the Complex Refractive Index Model (CRIM) to obtain a one dimensional model of interval layer velocities presumably representing the vertical distribution of gas content. CMP surveys were conducted at several locations in Caribou Bog peatland (Orono, Maine) in order to assess how peat thickness and surface vegetation communities may be impact FPG accumulation in the sub-surface. These locations include an open pool system, a low shrub heath area and a densely forested zone. As well as having variable surface vegetation communities, the total peat thickness is distinctly different at each of these sites. Preliminary results suggest that the CMP models are distinctly different between these sites and suggest a dependence of FPG accumulation on vegetation type.

  17. Post-Fire Moss Recovery in Northern Peatlands: Separating the Effects of Species and Water Content on Moss Water Repellency

    NASA Astrophysics Data System (ADS)

    Moore, Paul; Lukenbach, Max; Waddington, James Michael

    2016-04-01

    Wildfire is the largest disturbance affecting peatlands, where northern peat reserves are becoming increasingly vulnerable to wildfire as climate change is projected to enhance the length and severity of the fire season. However, little is known about the spatio-temporal variability of post-fire recovery in these ecosystems. High water table positions after wildfire are critical to limit atmospheric carbon losses and enable the re-establishment of keystone peatland mosses (i.e., Sphagnum). Post-fire recovery of the moss surface in Sphagnum-feathermoss peatlands, however, has been shown to be limited where moss type and burn severity interact to result in a water repellent surface. While in situ measurements of moss water repellency in peatlands has been shown to be greater for feathermoss in both a burned and unburned state in comparison to Sphagnum moss, it is difficult to separate effects of water content from species. Consequently, we carried out a drying experiment in the lab where we compared the water repellency of two dominant peatland moss species, Sphagnum and feathermoss, for several burn severity classes as well as for unburned samples. The results suggest that water repellency in moss is primarily controlled by water content, where a sharp threshold exists at gravimetric water contents (GWC) lower than ~3 g g-1. While GWC is shown to be a strong predictor of water repellency, the effect is enhanced by combustion. Based on field GWC, we show that there are significant differences in the frequency distribution of near-surface GWC between moss type and burn severity. The differences in the distributions of field GWC are related to characteristic moisture retention curves of unburned samples measured in the lab, as well as morphological differences between moss type.

  18. Initial response of the nitrogen cycle to soil warming in Northern Minnesota peatlands

    EPA Science Inventory

    Peatlands store 30% of global soil carbon. Many of these peatlands are located in boreal regions which are expected to have the highest temperature increases in response to climate change. As climate warms, peat decomposition may accelerate and release greenhouse gases. Spruce a...

  19. Age-dependent impacts of peatland restoration on the net ecosystem CO2 exchange of blanket bogs in Northern Scotland

    NASA Astrophysics Data System (ADS)

    Hambley, Graham; Hill, Timothy; Saunders, Matthew; Arn Teh, Yit

    2015-04-01

    The Flow Country of Northern Scotland is the largest area of contiguous blanket bog in the UK covering an area in excess of 400 km2. This region is the single largest peat and soil C repository in the UK, and plays a key role in mediating regional atmospheric exchanges of greenhouse gases (GHGs) such as carbon dioxide (CO2), methane (CH4) and water vapour (H2O). However, these peatlands were subject to significant afforestation in the 1980s, where large areas of blanket bog were drained and planted with Sitka spruce (Picea sitchensis) and Lodgepole Pine (Pinus contorta), resulting in modifications to micro-topographic features, vegetation composition and soil properties such as bulk density and water holding capacity, all of which are known to influence the production and emission of key GHGs. Since the late 1990s restoration work has been undertaken to remove forest plantations and to restore the peatland areas by raising the water table, predominantly by drain and furrow blocking, in order to encourage the recolonisation of Sphagnum species. Here we report findings from an eddy covariance study of CO2 and H2O exchange from an unmanaged peatland and a chronosequence of restored peatland sites, which were felled in 1998 and 2004. Located within the Forsinard Flows National Nature Reserve in Northern Scotland, these sites are being studied to better understand the key drivers of carbon dynamics in these ecosystems and also assess the age-dependent impacts of peatland restoration on the net CO2 sink strength. Preliminary data show rates of CO2 uptake increased with time since restoration, with peak assimilation rates of -9.9 and -14.4 micro mol CO2 m-2 s-1 measured at the 10 and 16 year old restoration sites, respectively. Carbon losses through ecosystem respiration followed a similar pattern. The data collected to date indicates that while peatland restoration is actively increasing CO2 uptake at each of the sites, more long-term observational data is required to

  20. Biogeochemical indicators of peatland degradation - a case study of a temperate bog in northern Germany

    NASA Astrophysics Data System (ADS)

    Kruger, J. P.; Leifeld, J.; Glatzel, S.; Szidat, S.; Alewell, C.

    2015-05-01

    Organic soils in peatlands store a great proportion of the global soil carbon pool and can lose carbon via the atmosphere due to degradation. In Germany, most of the greenhouse gas (GHG) emissions from organic soils are attributed to sites managed as grassland. Here, we investigated a land use gradient from near-natural wetland (NW) to an extensively managed (GE) to an intensively managed grassland site (GI), all formed in the same bog complex in northern Germany. Vertical depth profiles of δ13C, δ15N, ash content, C / N ratio and bulk density as well as radiocarbon ages were studied to identify peat degradation and to calculate carbon loss. At all sites, including the near-natural site, δ13C depth profiles indicate aerobic decomposition in the upper horizons. Depth profiles of δ15N differed significantly between sites with increasing δ15N values in the top soil layers paralleling an increase in land use intensity owing to differences in peat decomposition and fertilizer application. At both grassland sites, the ash content peaked within the first centimetres. In the near-natural site, ash contents were highest in 10-60 cm depth. The ash profiles, not only at the managed grassland sites, but also at the near-natural site indicate that all sites were influenced by anthropogenic activities either currently or in the past, most likely due to drainage. Based on the enrichment of ash content and changes in bulk density, we calculated the total carbon loss from the sites since the peatland was influenced by anthropogenic activities. Carbon loss at the sites increased in the following order: NW < GE < GI. Radiocarbon ages of peat in the topsoil of GE and GI were hundreds of years, indicating the loss of younger peat material. In contrast, peat in the first centimetres of the NW was only a few decades old, indicating recent peat growth. It is likely that the NW site accumulates carbon today but was perturbed by anthropogenic activities in the past. Together, all

  1. Long-term impacts of peatland restoration on the net ecosystem exchange (NEE) of blanket bogs in Northern Scotland.

    NASA Astrophysics Data System (ADS)

    Hambley, Graham; Hill, Timothy; Saunders, Matthew; Arn Teh, Yit

    2016-04-01

    Unmanaged peatlands represent an important long-term C sink and thus play an important part of the global C cycle. Despite covering only 12 % of the UK land area, peatlands are estimated to store approximately 20 times more carbon than the UK's forests, which cover 13% of the land area. The Flow Country of Northern Scotland is the largest area of contiguous blanket bog in the UK, and one of the biggest in Europe, covering an area in excess of 4000 km2 and plays a key role in mediating regional atmospheric exchanges of greenhouse gases (GHGs) such as carbon dioxide (CO2), and water vapour (H2O). However, these peatlands underwent significant afforestation in the 1980s, when over 670 km2 of blanket bog were drained and planted with Sitka spruce (Picea sitchensis) and Lodgepole pine (Pinus contorta). This resulted in modifications to hydrology, micro-topography, vegetation and soil properties all of which are known to influence the production, emission and sequestration of key GHGs. Since the late 1990s restoration work has been carried out to remove forest plantations and raise water tables, by drain blocking, to encourage the recolonisation of Sphagnum species and restore ecosystem functioning. Here, we report findings of NEE and its constituent fluxes, GPP and Reco, from a study investigating the impacts of restoration on C dynamics over a chronosequence of restored peatlands. The research explored the role of environmental variables and microtopography in modulating land-atmosphere exchanges, using a multi-scale sampling approach that incorporated eddy covariance measurements with dynamic flux chambers. Key age classes sampled included an undrained peatland; an older restored peatland (17 years old); and a more recently restored site (12 years old). The oldest restored site showed the strongest uptake of C, with an annual assimilation rate of 858 g C m-2 yr-1 compared to assimilation rates of 501g C m-2 yr-1 and 575g C m-2 yr-1 from the younger restored site and

  2. Water Research within the SPRUCE Experiment, a Large-Scale Study of Climate Change Effects on a Northern Peatland

    NASA Astrophysics Data System (ADS)

    Mulholland, P. J.; Sebestyen, S. D.; Hanson, P. J.; Warren, J.; Kolka, R. K.

    2010-12-01

    Scientists at the Oak Ridge National Laboratory and the USDA Forest Service along with cooperating research institutions are developing a large-scale ecosystem study in which temperature and carbon dioxide will be experimentally increased to quantify effects of climatic forcing on ecological, hydrological, and biogeochemical processes in a northern peatland. In this poster, we provide an overview of the water science research directions within the Spruce and Peatland Responses Under Climate and Environmental change Experiment (SPRUCE) that will occur at the Marcell Experiment Forest in northern Minnesota, USA. Design and prototyping is now occurring with full operation for 10 years starting in 2013. Air and soil temperatures inside replicated 12-m diameter, open-topped chambers will be maintained at ambient, +3, +6, and +9 degrees Celsius with enhanced carbon dioxide (+900 ppm in the ambient and +6 degree treatments). We will quantify changes in the timing and magnitude of runoff due to earlier snowmelt and longer growing seasons as well as associated changes in runoff chemistry. Measurements of plant-water, physiological, and vapor flux responses from the chambers will advance our understanding of hydrological responses and thresholds of climate tipping points. This experiment will provide quantitative evidence of the effects of climatic forcing by temperature and elevated carbon dioxide on northern peatland ecosystems and the vast stores of carbon that are associated with the hydrology and biogeochemistry of these globally widespread landscape features. The data are also crucial to predicting feedbacks on global climate as well as water availability, solute yields, and biogeochemical transformations in these ecosystems.

  3. The relative importance of methanogenesis in the decomposition of organic matter in northern peatlands

    NASA Astrophysics Data System (ADS)

    Corbett, J. Elizabeth; Tfaily, Malak M.; Burdige, David J.; Glaser, Paul H.; Chanton, Jeffrey P.

    2015-02-01

    Using an isotope-mass balance approach and assuming the equimolar production of CO2 and CH4 from methanogenesis (e.g., anaerobic decomposition of cellulose), we calculate that the proportion of total CO2 production from methanogenesis varies from 37 to 83% across a variety of northern peatlands. In a relative sense, methanogenesis was a more important pathway for decomposition in bogs (80 ± 13% of CO2 production) than in fens (64 ± 5.7% of CO2 production), but because fens contain more labile substrates they may support higher CH4 production overall. The concentration of CO2 produced from methanogenesis (CO2-meth) can be considered equivalent to CH4 concentration before loss due to ebullition, plant-mediated transport, or diffusion. Bogs produced slightly less CO2-meth than fens (2.9 ± 1.3 and 3.7 ± 1.4 mmol/L, respectively). Comparing the quantity of CH4 present to CO2-meth, fens lost slightly more CH4 than bogs (89 ± 2.8% and 82 ± 5.3%, respectively) likely due to the presence of vascular plant roots. In collapsed permafrost wetlands, bog moats produced half the amount of CO2-meth (0.8 ± 0.2 mmol/L) relative to midbogs (1.6 ± 0.6 mmol/L) and methanogenesis was less important (42 ± 6.6% of total CO2 production relative to 55 ± 8.1%). We hypothesize that the lower methane production potential in collapsed permafrost wetlands occurs because recently thawed organic substrates are being first exposed to the initial phases of anaerobic decomposition following collapse and flooding. Bog moats lost a comparable amount of CH4 as midbogs (63 ± 7.0% and 64 ± 9.3%).

  4. The Relative Importance of Methanogenesis in the Decomposition of Organic Matter in Northern Peatlands

    NASA Technical Reports Server (NTRS)

    Corbett, J. Elizabeth; Tfaily, Malak M.; Burdige, David J.; Glaser, Paul H.; Chanton, Jeffrey P.

    2015-01-01

    Using an isotope-mass balance approach and assuming the equimolar production of CO2 and CH4 from methanogenesis (e.g., anaerobic decomposition of cellulose), we calculate that the proportion of total CO2 production from methanogenesis varies from 37 to 83% across a variety of northern peatlands. In a relative sense, methanogenesis was a more important pathway for decomposition in bogs (80 +/- 13% of CO2 production) than in fens (64 +/- 5.7% of CO2 production), but because fens contain more labile substrates they may support higher CH4 production overall. The concentration of CO2 produced from methanogenesis (CO2-meth) can be considered equivalent to CH4 concentration before loss due to ebullition, plant-mediated transport, or diffusion. Bogs produced slightly less CO2-meth than fens (2.9 +/- 1.3 and 3.7 +/- 1.4 mmol/L, respectively). Comparing the quantity of CH4 present to CO2-meth, fens lost slightly more CH4 than bogs (89 +/- 2.8% and 82 +/- 5.3%, respectively) likely due to the presence of vascular plant roots. In collapsed permafrost wetlands, bog moats produced half the amount of CO2-meth (0.8 +/- 0.2mmol/L) relative to midbogs (1.6 +/- 0.6 mmol/L) and methanogenesis was less important (42 +/- 6.6% of total CO2 production relative to 55 +/- 8.1%).We hypothesize that the lower methane production potential in collapsed permafrost wetlands occurs because recently thawed organic substrates are being first exposed to the initial phases of anaerobic decomposition following collapse and flooding. Bog moats lost a comparable amount of CH4 as midbogs (63 +/- 7.0% and 64 +/- 9.3%).

  5. The Effects of Peatland Plant Functional Types and Altered Hydrology on Porewater Chemistry in a Northern Bog

    NASA Astrophysics Data System (ADS)

    Daniels, A.; Kane, E. S.; Lilleskov, E. A.; Kolka, R. K.; Chimner, R. A.; Potvin, L. R.; Romanowicz, K. J.

    2012-12-01

    Northern wetlands, peatlands in particular, have been shown to store around 30% of the world's soil carbon and thus play a significant role in the carbon cycle of our planet. Carbon accumulation in peatlands is the result of retarded decomposition due to low oxygen availability in these water-logged environments. Changes in our planet's climate cycles are altering peatland hydrology and vegetation communities, resulting in changes in their ability to sequester carbon through increases in peat carbon oxidation and mineralization. To date, the consequences of altered hydrology and changes in vegetation communities, and their interactive effects on carbon storage, are not well understood. We have initiated a research plan that assesses the varying roles that water table variation and vegetation communities have on extracellular enzyme activity and labile carbon availability in porewater from an ombrotrophic bog. We assessed the effects of plant functional group (ericaceous shrubs, sedges, and bryophytes) and water table position on biogeochemical processes. Specifically, we measured dissolved organic carbon (DOC), total dissolved nitrogen (TDN), enzyme activity, organic acids, anions and cations, spectral indexes of aromaticity, and phenolic content in addressing our hypotheses of responses to climate change drivers. Research on these components will evaluate the relative importance of biology, water table, and their interactive affects on the porewater quality of peatlands. We hypothesized that oxygen availability will strongly influence decomposition in these systems but that this response will largely be mediated by changes in plant community and the enzymes associated with root exudates and mycorrhizae. To date, our data confirm vegetation and water table related patterns. Acetate and propionate concentrations in the sedge-dominated communities dropped significantly with depth and drainage, relative to the control and ericaceous treatments, which likely reflects

  6. Autonomous ground penetrating radar (GPR) measurements for exploring biogenic gas dynamics of peat soils in a northern peatland

    NASA Astrophysics Data System (ADS)

    Wright, W. J.; Comas, X.; Heij, G.; Slater, L. D.; Schafer, K. V.; Reeve, A. S.

    2012-12-01

    It is widely accepted that northern peat soils are responsible for up to 10% of methane flux to the atmosphere yet act as a net sink for as much as 75% of the global mass of atmospheric carbon. A better understanding of the processes by which peat soils store and release carbon products must be gained in order to more accurately model the contributions that peatlands make to global atmospheric carbon budgets. Rapid ebullition events of biogenic methane and carbon dioxide gases from peat soils are currently not well understood, particularly since the timing of the releases are poorly constrained. Ground penetrating radar (GPR) is a geophysical tool that has successfully been used in the past to non-invasively investigate the release of biogenic gasses from peat soils. In the work presented here, measurement frequency is expanded by including daily arrays of common offset and common midpoint GPR measurements combined with hourly autonomous GPR measurements to investigate biogenic gas dynamics during times of variable atmospheric pressure in a northern peatland in Maine. Geophysical data were supported by peat matrix deformation measurements using terrestrial LiDAR (TLS) and direct gas flux measurements using gas traps combined with time-lapse cameras at the sub-daily scale. A vertical array of moisture probes was also used to further constrain GPR measurements. Results from this study show the viability of autonomous GPR methods for improving temporal resolution of geophysical data in order to better understand the dynamics of biogenic gas releases from peat soils.

  7. Predicting permafrost stability in northern peatlands with climate change and disturbance

    NASA Astrophysics Data System (ADS)

    Treat, C. C.; Wisser, D.; Marchenko, S.; Humphreys, E. R.; Frolking, S. E.; Huemmrich, K. F.

    2010-12-01

    Permafrost thaw may cause significant carbon loss from northern organic soils, a large terrestrial carbon pool. To predict permafrost stability in organic soils, we adapted an existing soil temperature model (GIPL 2.0) to peatlands by including a three-layer peat soil column and dynamic soil moisture. GIPL 2.0 numerically solves the 1-dimensional heat transfer equation. We evaluated the model at Daring Lake Fen, a sedge-dominated Arctic Fen in the Northwest Territories, Canada and College Peat, a permafrost muskeg in Fairbanks, AK. We examined the sensitivity of the model to seasonality and total soil moisture, thermal properties and organic layer thickness. We also evaluated active layer depth for future climate scenarios. Finally, we compared the relative magnitude of climate change impacts on soil temperatures to the effects of current and predicted wildfire. We simulated wildfire by removing the surface soil (5 - 15 cm) and increasing air temperatures post-fire due to changes in surface energy balance. We found that air temperature, rather than changes in soil moisture, was the most important predictor of changes in active layer depth and permafrost stability. Also, the seasonality of soil moisture was relatively unimportant, while changes in temperature seasonality were important to active layer depths. In the climate change scenarios (using IPCC scenario A1b), active layer depths and the length of the growing season (determined as soil thawed at 10 cm) increased significantly by 2100. Warmer soil temperatures at depth due to higher air temperatures resulted in an increase of liquid water in the soil and the possibility of increased biological activity. Soil temperatures and active layer depths increased following disturbance, but the increases were relatively short-lived (decades) and were strongly correlated with post-fire temperature changes. The simulated removal of a shallow layer of surface organic soil following disturbance has limited long-term effects

  8. Proxy-Derived Reconstructions of Holocene Paleoclimate for the Hudson Bay Lowlands, an Extensive Peatland in Northern Canada

    NASA Astrophysics Data System (ADS)

    Finkelstein, S. A.; Bunbury, J.; Friel, C.; O'Reilly, B.

    2013-12-01

    The Hudson Bay Lowlands (HBL) is an extensive peatland in northern Canada where an estimated 31 Pg of carbon have accumulated during the Holocene. Given the large size of this carbon pool and the rapid rate of climate warming at high latitudes, quantifying the responses of this peatland to climate change is a critical research priority. Comparing Holocene paleoclimate reconstructions and paleo-vegetation and carbon dynamics in HBL peatlands through analyses of sediment cores is an effective approach to understanding the sensitivity of the carbon pool to climate. Robust paleoclimate reconstructions for the Holocene are needed for such comparisons. Until recently, there have been few paleoclimate reconstructions available for the HBL. Owing to the unique geographic setting of this low lying region to the west of Hudson Bay, reconstructions from adjacent subarctic regions are not directly applicable. We synthesize in this paper a series of paleoenvironmental records derived from biological proxies preserved in lake and wetland sediment cores collected from within the HBL with the goal of improving available paleoclimate information for the region. Our available pollen records document a series of vegetation changes during the Holocene, beginning with the establishment of coastal or salt marsh communities after emergence of the HBL from the Tyrrell Sea, followed by establishment of vegetation typical of poor fens or bogs. These local vegetation changes are apparently primarily related to hydrological changes driven by isostatic rebound and autogenic processes. Regional assemblages composed of tree pollen, which may be more directly tied to climate, show less variability during the Holocene. Reconstructions using modern analogs suggest minimal variation in temperature during the period of record, although these reconstructions show a moderate increase in precipitation following 3000 yrs BP, corresponding to Neoglacial climates reported at other northern high latitude

  9. Stable isotopes, radiocarbon signature and C loss as an indicator for soil degradation in a drained peatland, northern Germany

    NASA Astrophysics Data System (ADS)

    Krüger, Jan Paul; Leifeld, Jens; Glatzel, Stephan; Alewell, Christine

    2014-05-01

    Peatlands are an important component of the global carbon cycle. Even though they cover only about 3% of the global land area, they store approximately 600 Pg carbon (C) in their soils. Drainage for agriculture use, for example as grassland, induces oxic conditions in the upper part of a peat profile and increases the carbon dioxide emissions. Peatlands thus change from a carbon sink in pristine status to a carbon source under drainage and land use intensification. Detailed peat profile analyses in a drained peatland under grassland use in northern Germany were used to study the influence of drainage and land use management on stable isotope depth profiles and to calculate retrograde C losses by the ash method. Peat profiles (n=3) were taken from one semi-natural bog as reference and two adjacent drained peatlands located at the former peat bog which has been used as grassland (extensive, intensive use) for the last decades. The peatland drainage started at the beginning of the 20th century and land use was intensified in the middle of the 20th century. The semi-natural peatland is unmanaged, the extensive grassland is neither fertilized nor manured and only cut once per year and the intensive grassland is cut 4-5 times per year and fertilized with mineral fertilizer and manure. All grassland peat cores show a clear ash peak in the upper most centimetre of the profile indicating an accumulation of ash caused by the oxidation of the organic material. Calculated carbon losses since the drainage of the peatland are 540 (±156) and 290 (±36) t C ha-1for the intensive and extensive used grassland, respectively. The constant background ash values from the lower profile were taken as reference values, because even the semi-natural site accumulated ash in the topsoil and has lost 144 (±98) t C ha-1 based on this method. A likely drainage influence by the surrounding area is also reflected in the δ13C values of the semi-natural site with an increase of the δ13C values

  10. Ten-year interannual and seasonal variability of stream carbon export from a boreal peatland in northern Sweden

    NASA Astrophysics Data System (ADS)

    Leach, J.; Larsson, A.; Nilsson, M. B.; Laudon, H.

    2015-12-01

    High latitude peatlands constitute about 3% of the global land cover but store almost a third of the global soil carbon pool. The annual net ecosystem carbon balance at high latitude mires results from the balance between net ecosystem exchange, methane emission and stream discharge export. Understanding stream carbon export dynamics is needed to accurately predict how the carbon balance of peatlands will respond to climatic and environmental change. We use a ten year record (2004-2014) of streamflow and dissolved carbon (DOC, DIC, and CH4) measurements to assess interannual and seasonal variability in stream carbon export for a peatland catchment in northern Sweden. Mean annual total carbon export for the ten year period was 11.4 gC/m2, but individual years ranged between 6.1 and 17.2 gC/m2. DOC was the dominant form of carbon being exported, comprising 68% to 76% of total annual exports, and DIC contributed between 24% and 30%. CH4 made up less than 3% of total export. Stream carbon export and streamflow were highly synchronous. The majority of export (30% to 55% of annual totals) occurred during the spring snowmelt period. Exports during the summer and autumn were highly variable (1% to 45% and 9% to 53% of annual totals, respectively) and depended on the timing and magnitude of rain events. Winter periods were characterized by low streamflow conditions and associated low carbon export (0.6% to 10% of annual totals). These results highlight considerable interannual and seasonal variability of stream carbon export driven primarily by rain and snowmelt runoff events.

  11. Retention of contaminants in northern natural peatlands treating mine waste waters

    NASA Astrophysics Data System (ADS)

    Palmer, Katharina; Ronkanen, Anna-Kaisa; Klöve, Björn

    2014-05-01

    The mining industry in Finland is growing, leading to an increasing number of working and proposed mine sites. As a consequence, the amount of mine waste waters created is likewise increasing. This poses a great challenge for water management and purification, as these mine waste waters can lead to severe environmental and health consequences when released to receiving water bodies untreated. In the past years, the use of natural peatlands for cost-effective passive waste water treatment has been increasing. In this study, the fate of mine water contaminants in a treatment peatland receiving process waters from the Kittilä gold mine was investigated. Special attention was paid to the fate of potentially harmful substances such as arsenic, antimony or nickel. During the 4 years of operation, the peatland removed contaminants from process waters at varying efficiencies. While arsenic, antimony and nickel were retained at high efficiencies (>80% retention), other contaminants such as zinc, sulfate or iron were not retained or even leaching from the peatland. Soil samples taken in 2013 showed a linear increase of arsenic, antimony and nickel concentration in the peatland as compared to earlier sampling times, in agreement with the good retention efficiencies for those contaminants. Measured concentrations exceeded guideline values for contaminated soils, indicating that the prolonged use of treatment peatlands leads to high soil contamination and restrict further uses of the peatlands without remediation measures. Soil and pore water samples were taken along a transect with varying distance from the process water distribution ditch and analyzed for total and more easily mobile concentrations of contaminants (peat soil) as well as total and dissolved contaminants (water samples). Concentrations of contaminants such as arsenic, manganese or antimony in peat and pore water samples were highest near the distribution ditch and decreased with increasing distance from the

  12. A satellite data driven biophysical modeling approach for estimating northern peatland and tundra CO2 and CH4 fluxes

    NASA Astrophysics Data System (ADS)

    Watts, J. D.; Kimball, J. S.; Parmentier, F.-J. W.; Sachs, T.; Rinne, J.; Zona, D.; Oechel, W.; Tagesson, T.; Jackowicz-Korczyński, M.; Aurela, M.

    2013-10-01

    The northern terrestrial net ecosystem carbon balance (NECB) is contingent on inputs from vegetation gross primary productivity (GPP) to offset ecosystem respiration (Reco) of carbon dioxide (CO2) and methane (CH4) emissions, but an effective framework to monitor the regional Arctic NECB is lacking. We modified a terrestrial carbon flux (TCF) model developed for satellite remote sensing applications to estimate peatland and tundra CO2 and CH4 fluxes over a pan-Arctic network of eddy covariance (EC) flux tower sites. The TCF model estimates GPP, CO2 and CH4 emissions using either in-situ or remote sensing based climate data as input. TCF simulations driven using in-situ data explained >70% of the r2 variability in 8 day cumulative EC measured fluxes. Model simulations using coarser satellite (MODIS) and reanalysis (MERRA) data as inputs also reproduced the variability in the EC measured fluxes relatively well for GPP (r2 = 0.75), Reco (r2 = 0.71), net ecosystem CO2 exchange (NEE, r2 = 0.62) and CH4 emissions (r2 = 0.75). Although the estimated annual CH4 emissions were small (<18 g C m-2 yr-1) relative to Reco (>180 g C m-2 yr-1), they reduced the across-site NECB by 23% and contributed to a global warming potential of approximately 165 ± 128 g CO2eq m-2 yr-1 when considered over a 100 yr time span. This model evaluation indicates a strong potential for using the TCF model approach to document landscape scale variability in CO2 and CH4 fluxes, and to estimate the NECB for northern peatland and tundra ecosystems.

  13. Drawing to Learn Science: Legacies of Agassiz

    ERIC Educational Resources Information Center

    Lerner, Neal

    2007-01-01

    The use of visual representation to learn science can be traced to Louis Agassiz, Harvard Professor of Zoology, in the mid-19th century. In Agassiz's approach, students were to study nature through carefully observing, drawing and then thinking about what the observations might add up to. However, implementation of Agassiz's student-centered…

  14. Simulation of six years of carbon fluxes for a sedge-dominated oligotrophic minerogenic peatland in Northern Sweden using the McGill Wetland Model (MWM)

    NASA Astrophysics Data System (ADS)

    Wu, Jianghua; Roulet, Nigel T.; Sagerfors, Jorgen; Nilsson, Mats B.

    2013-06-01

    Northern peatlands store ~30% of the global soil carbon, despite covering only 3% of the land. To understand the carbon balance of these systems and predict their response to changes in climate, robust and reliable models are needed. The McGill Wetland Model (MWM), originally developed to simulate the carbon dynamics of ombrotrophic bogs, was modified to simulate the CO2 biogeochemistry of sedge-dominated oligotrophic minerogenic peatlands, a prominent peatland type in boreal and subarctic landscapes. Three modifications were implemented: (1) a function to describe the impact of soil moisture on the optimal gross primary production, (2) a scheme to partition the peat profile into oxic and anoxic compartments based on the "effective root depth" as a function of daily sedge net primary production, and (3) a function to describe the "fen" moss water dynamics. The modified MWM was evaluated using eddy-covariance net ecosystem production (NEP) from Degero Stormyr in northern Sweden. The root mean square error for daily NEP was ~0.46 g C m-2 d-1, and the index of agreement was 84%. This model adequately captures the magnitude and direction of the CO2 fluxes and simulates the seasonal and inter-annual variability reasonably well (r2 > 0.8). Sensitivity analysis confirms that specifically water table depth (WTD) and moss water content are key biogeochemical hydrology processes for the carbon biogeochemistry of a sedge-dominated oligotrophic minerogenic peatland. An increase of WTD by 15 cm or air temperature by 3°C could decrease NEP by up to 200% and make the peatland become a source of CO2.

  15. Peat landforms along the Albany River, northern Ontario. An ecological study of peat landforms in Canada and Alaska

    NASA Technical Reports Server (NTRS)

    Glaser, P. H.

    1985-01-01

    During the summer of 1985 a field investigation was started in the Hudson Bay lowland region of northern Ontario, which represents the largest expanse of peatland in North America and is an important sink in the global carbon cycle. A key area in the lowlands is situated along the Albany River near the confluence of the Chepay River. Here the striking vegetation-landforms are transitional between those found on the bed of Glacial Lake Agassiz in northern Minnesota and southern Manitoba and the more northern peatlands in the Hudson Bay lowland region. In peatland studies elsewhere the landform patterns have been used not only to classify different peatland types but also as an indicator of potential developmetnal trends. The study area is generally defined by that covered by the TM scene E-40062-15532 taken on Sept. 16, 1982. The purpose of the field work is to acquire sufficent information to interpret the TM imagery and test various hypotheses on peatland development on the gasis of the pattern transitions.

  16. Estimation of Biogenic Gas Distribution in a Northern Peatland Using Surface and Borehole Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Comas, X.; Slater, L.; Reeve, A.

    2005-05-01

    A combination of borehole and surface ground penetrating radar (GPR), time domain reflectometry (TDR) and direct gas sampling was performed to detect biogenic gas accumulation areas in Caribou Bog, a multi-unit peatland in central Maine (Orono). Areas of electromagnetic (EM) signal scattering (or shadow zones, similar to those reported with the seismic reflection method) observed in the surface GPR coincide with sampled zones of high CH4 and CO2 concentration. Shadow zones also correlate with areas of high EM wave velocity detected in zero offset profiles (ZOP) conducted with the borehole GPR, and with areas of low water content inferred with TDR. Application of the Complex Refractive Index Model (CRIM) to the EM wave velocities implies that the anomalous high velocity zones results from a volumetric gas content of 7% and 10% for a peat soil porosity of 91% and 94% respectively. In the absence of gas, the CRIM model predicts a porosity value of only 84% to reach the maximum EM wave velocity recorded, a value not supported by our peat porosity measurements in the laboratory and inconsistent with the high porosity of peat recorded by others. Strong reflectors detected with the surface GPR are interpreted as confining layers acting as biogenic gas traps and inducing overpressurized biogenic gas pockets as postulated by others. Spatial gas distribution and volumetric gas content can be roughly estimated considering the areas affected by EM wave blanking. These findings also have implications for the monitoring of temporal behavior of biogenic gas emissions to the atmosphere from peatlands.

  17. Dissolved Organic Carbon Cycling and Transformation Dynamics in A Northern Forested Peatland

    NASA Astrophysics Data System (ADS)

    Tfaily, M. M.; Lin, X.; Chanton, P. R.; Steinweg, J.; Esson, K.; Kostka, J. E.; Cooper, W. T.; Schadt, C. W.; Hanson, P. J.; Chanton, J.

    2013-12-01

    Peatlands sequester one-third of all soil carbon and currently act as major sinks of atmospheric carbon dioxide. The ability to predict or simulate the fate of stored carbon in response to climatic disruption remains hampered by our limited understanding of the controls of carbon turnover and the composition and functioning of peatland microbial communities. A combination of advanced analytical chemistry and microbiology approaches revealed that organic matter reactivity and microbial community dynamics were closely coupled in an extensive field dataset compiled at the S1 bog site established for the SPRUCE program, Marcell Experimental Forest (MEF). The molecular composition and decomposition pathways of dissolved organic carbon (DOC) were contrasted using parallel factor (PARAFAC)-modeled excitation emission fluorescence spectroscopy (EEMS) and FT-ICR MS. The specific UV absorbance (SUVA) at 254 nm was calculated as an indicator of aromaticity. Fluorescence intensity ratios (BIX and FI) were used to infer the relative contributions from solid phase decomposition and microbial production. Distributions of bulk DOC, its stable (δ13C) and radioactive (Δ14C) isotopic composition were also utilized to infer information on its dynamics and transformation processes. Strong vertical stratification was observed in organic matter composition, the distribution of mineralization products (CO2, CH4), respiration rates, and decomposition pathways, whereas smaller variations were observed between sites. A decline in the aromaticity of pore water DOC was accompanied by an increase in microbially-produced DOC. Solid phase peat, on the other hand, became more humified and highly aromatic with depth. These observations were consistent with radiocarbon data that showed that the radiocarbon signatures of microbial respiration products in peat porewaters more closely resemble those of DOC rather than solid peat, indicating that carbon from recent photosynthesis is fueling the

  18. Ecological controls on methane emissions from a northern peatland complex, Manitoba, Canada

    SciTech Connect

    Bubier, J.L.; Moore, T.R.

    1995-06-01

    This study measured methane (CH{sub 4}) emissions by a static chamber technique from a wide range of sites (pH 3.9 - 7.0) in a peatland complex near Thompson, Manitoba in the Boreal Ecosystem - Atmosphere Study (BOREAS). The objectives were to identify environmental controls on CH{sub 4} emission rates, determine their spatial and temporal variability, and examine the change in CH{sub 4} emission associated with the evolution of permafrost, palsas, and collapse scars. Peak CH{sub 4} fluxes ranged from 0 in the palsas and treed peat islands to 1200 mg m{sup -2} d{sup -1} in the open sedge-rich fens and saturated lagg areas of collapse scars, where permafrost was actively degrading. The greatest variability in fluxes occurred in flooded sites where ebullition was a transport mechanism. Depth to water table and peat temperature at the average water table position explained most of the variability in CH{sub 4} fluxes, with plant composition and density, substrate type, and the CH{sub 4} production/consumption potentials of the various peats as additional factors. CH{sub 4} flux did not vary with pH in the field since water table position and temperature were overriding controls.

  19. A satellite data driven biophysical modeling approach for estimating northern peatland and tundra CO2 and CH4 fluxes

    NASA Astrophysics Data System (ADS)

    Watts, J. D.; Kimball, J. S.; Parmentier, F. J. W.; Sachs, T.; Rinne, J.; Zona, D.; Oechel, W.; Tagesson, T.; Jackowicz-Korczyński, M.; Aurela, M.

    2014-04-01

    The northern terrestrial net ecosystem carbon balance (NECB) is contingent on inputs from vegetation gross primary productivity (GPP) to offset the ecosystem respiration (Reco) of carbon dioxide (CO2) and methane (CH4) emissions, but an effective framework to monitor the regional Arctic NECB is lacking. We modified a terrestrial carbon flux (TCF) model developed for satellite remote sensing applications to evaluate wetland CO2 and CH4 fluxes over pan-Arctic eddy covariance (EC) flux tower sites. The TCF model estimates GPP, CO2 and CH4 emissions using in situ or remote sensing and reanalysis-based climate data as inputs. The TCF model simulations using in situ data explained > 70% of the r2 variability in the 8 day cumulative EC measured fluxes. Model simulations using coarser satellite (MODIS) and reanalysis (MERRA) records accounted for approximately 69% and 75% of the respective r2 variability in the tower CO2 and CH4 records, with corresponding RMSE uncertainties of ≤ 1.3 g C m-2 d-1 (CO2) and 18.2 mg C m-2 d-1 (CH4). Although the estimated annual CH4 emissions were small (< 18 g C m-2 yr-1) relative to Reco (> 180 g C m-2 yr-1), they reduced the across-site NECB by 23% and contributed to a global warming potential of approximately 165 ± 128 g CO2eq m-2 yr-1 when considered over a 100 year time span. This model evaluation indicates a strong potential for using the TCF model approach to document landscape-scale variability in CO2 and CH4 fluxes, and to estimate the NECB for northern peatland and tundra ecosystems.

  20. Elucidating effects of atmospheric deposition and peat decomposition processes on mercury accumulation rates in a northern Minnesota peatland over last 10,000 cal years

    NASA Astrophysics Data System (ADS)

    Nater, E. A.; Furman, O.; Toner, B. M.; Sebestyen, S. D.; Tfaily, M. M.; Chanton, J.; Fissore, C.; McFarlane, K. J.; Hanson, P. J.; Iversen, C. M.; Kolka, R. K.

    2014-12-01

    Climate change has the potential to affect mercury (Hg), sulfur (S) and carbon (C) stores and cycling in northern peatland ecosystems (NPEs). SPRUCE (Spruce and Peatland Responses Under Climate and Environmental change) is an interdisciplinary study of the effects of elevated temperature and CO2 enrichment on NPEs. Peat cores (0-3.0 m) were collected from 16 large plots located on the S1 peatland (an ombrotrophic bog treed with Picea mariana and Larix laricina) in August, 2012 for baseline characterization before the experiment begins. Peat samples were analyzed at depth increments for total Hg, bulk density, humification indices, and elemental composition. Net Hg accumulation rates over the last 10,000 years were derived from Hg concentrations and peat accumulation rates based on peat depth chronology established using 14C and 13C dating of peat cores. Historic Hg deposition rates are being modeled from pre-industrial deposition rates in S1 scaled by regional lake sediment records. Effects of peatland processes and factors (hydrology, decomposition, redox chemistry, vegetative changes, microtopography) on the biogeochemistry of Hg, S, and other elements are being assessed by comparing observed elemental depth profiles with accumulation profiles predicted solely from atmospheric deposition. We are using principal component analyses and cluster analyses to elucidate relationships between humification indices, peat physical properties, and inorganic and organic geochemistry data to interpret the main processes controlling net Hg accumulation and elemental concentrations in surface and subsurface peat layers. These findings are critical to predicting how climate change will affect future accumulation of Hg as well as existing Hg stores in NPE, and for providing reference baselines for SPRUCE future investigations.

  1. How do climate and human impact affect Sphagnum peatlands under oceanic-continental climatic conditions? 2000 years of fire and hydrological history of a bog in Northern Poland

    NASA Astrophysics Data System (ADS)

    Marcisz, Katarzyna; Tinner, Willy; Colombaroli, Daniele; Kołaczek, Piotr; Słowiński, Michał; Fiałkiewicz-Kozieł, Barbara; Lamentowicz, Mariusz

    2014-05-01

    Climate change affects many natural processes and the same applies to human impact For instance climate change and anthropogenic activities may cause increased fire activity or change peatland dynamics. Currently it is still unknown how Sphagnum peatlands in the oceanic-continental transition zone of Poland may respond to combined effects of heat waves, drought and fire. The aim of the study was to reconstruct the last 2000 years palaeohydrology and fire history at Linje bog in Northern Poland. The main task was to determine the drivers of fire episodes, particularly to identify climatic and anthropogenic forcing. A two-meter peat core was extracted and subsampled with a high resolution. Micro- and macroscopic charcoal analyses were applied to determine past fire activity and the results compared with palaeohydrological reconstructions based on testate amoeba analysis. Palynological human indicators were used to reconstruct human activity. A depth-age model including 20 14C dates was constructed to calculate peat accumulation rates and charcoal influx. We hypothesised that: 1) fire frequency in Northern Poland was determined by climatic conditions (combination of low precipitation and heat waves), as reflected in peatland water table, and that 2) past fire episodes in the last millennium were intensified by human activity. Furthermore climate may have influenced human activity over harvest success and the carrying capacity. Our study shows that fire was important for the studied ecosystem, however, its frequency has increased in the last millennium in concomitance with land use activities. Landscape humanization and vegetation opening were followed by a peatland drying during the Little Ice Age (from ca. AD 1380). Similarly to other palaeoecological studies from Poland, Linje peatland possessed an unstable hydrology during the Little Ice Age. Increased fire episodes appeared shortly before the Little Ice Age and most severe fires were present in the time when

  2. Ideas and perspectives: why Holocene thermokarst sediments of the Yedoma region do not increase the northern peatland carbon pool

    NASA Astrophysics Data System (ADS)

    Hugelius, G.; Kuhry, P.; Tarnocai, C.

    2015-11-01

    Permafrost deposits in the Beringian Yedoma region store large amounts of organic carbon (OC). Walter Anthony et al. (2014) describe a previously unrecognized pool of 159 Pg OC accumulated in Holocene thermokarst sediments deposited in Yedoma region alases (thermokarst depressions). They claim that these alas sediments increase the previously recognized circumpolar permafrost peat OC pool by 50 %. It is stated that previous integrated studies of the permafrost OC pool have failed to account for these deposits because the Northern Circumpolar Soil Carbon Database (NCSCD) is biased towards non-alas field sites and that the soil maps used in the NCSCD underestimate coverage of organic permafrost soils. Here we evaluate these statements against a brief literature review, existing datasets on Yedoma region soil OC storage and independent field-based and geospatial datasets of peat soil distribution in the Siberian Yedoma region. Our findings are summarised in three main points. Firstly, the sediments described by Walter Anthony et al. are primarily mineral lake sediments and do not match widely used international scientific definitions of peat or organic soils. They can therefore not be considered an addition to the circumpolar peat carbon pool. Secondly, independent field data and geospatial analyses show that the Siberian Yedoma regions is dominated by mineral soils, not peatlands. Thus, there is no evidence to suggest any systematic bias in the NCSCD field data or maps. Thirdly, there is spatial overlap between these Holocene thermokarst sediments and previous estimates of permafrost soil and sediment OC stocks. These carbon stocks were already accounted for by previous studies and cannot be added to the permafrost OC count. We suggest that statements made in Walter Anthony et al. (2014) resulted from misunderstandings caused by conflicting definitions and terminologies across different geoscientific disciplines. A careful cross-disciplinary review of terminologies

  3. Controls on northern wetland methane emissions: insights from regional synthesis studies and the Alaska Peatland Experiment (APEX)

    NASA Astrophysics Data System (ADS)

    Turetsky, M. R.; Euskirchen, E. S.; Czimczik, C. I.; Waldrop, M. P.; Olefeldt, D.; Fan, Z.; Kane, E. S.; McGuire, A. D.; Harden, J. W.

    2014-12-01

    Wetlands are the largest natural source of atmospheric methane. Static chambers have been used to quantify variation in wetland CH4 flux for many decades. Regional to global scale synthesis studies of static chamber measurements show that relationships between temperature, water availability and CH4 emissions depend on wetland type (bog, fen, swamp), region (tropical, temperate, arctic) and disturbance. For example, while water table position and temperature serve as the dominant controls on bog and swamp CH4 flux, vegetation is an important control on emissions from fens. These studies highlight the fact that wetland types have distinct controls on CH4 emissions; however, it is unlikely that modeling of wetland CH4 flux will improve without a better mechanistic understanding of the processes underlying CH4 production, transport, and oxidation. At the Alaska Peatland Experiment, we are quantifying CH4 emission using static chambers, automated chambers, and towers. Our sites vary in permafrost regime, including groundwater fens without permafrost, forested peat plateaus with intact permafrost, and collapse scar bogs formed through permafrost thaw. Experimental studies that examine plant and microbial responses to altered water table position and soil temperature are complemented by a gradient approach, where we use a space-for-time substitutions to examine the consequences of thaw on time-scales of decades to centuries. Our results thus far have documented the importance of soil rewetting in governing large CH4 fluxes from northern wetland soils. Accounting for CH4, our collapse scar bog significantly contributed to the global warming potential of the landscape. A major objective of our work is to explore the role of permafrost C release in greenhouse gas fluxes from wetland soils, which we are assessing using radiocarbon as a natural tracer. We have shown, for example, that ebullition of CH4 is dominated by recently fixed C, but a significant fraction of CH4 in

  4. Ideas and perspectives: Holocene thermokarst sediments of the Yedoma permafrost region do not increase the northern peatland carbon pool

    NASA Astrophysics Data System (ADS)

    Hugelius, Gustaf; Kuhry, Peter; Tarnocai, Charles

    2016-04-01

    Permafrost deposits in the Beringian Yedoma region store large amounts of organic carbon (OC). Walter Anthony et al. (2014) describe a previously unrecognized pool of 159 Pg OC accumulated in Holocene thermokarst sediments deposited in Yedoma region alases (thermokarst depressions). They claim that these alas sediments increase the previously recognized circumpolar permafrost peat OC pool by 50 %. It is stated that previous integrated studies of the permafrost OC pool have failed to account for these deposits because the Northern Circumpolar Soil Carbon Database (NCSCD) is biased towards non-alas field sites and that the soil maps used in the NCSCD underestimate coverage of organic permafrost soils. Here we evaluate these statements against a brief literature review, existing data sets on Yedoma region soil OC storage and independent field-based and geospatial data sets of peat soil distribution in the Siberian Yedoma region. Our findings are summarized in three main points. Firstly, the sediments described by Walter Anthony et al. (2014) are primarily mineral lake sediments and do not match widely used international scientific definitions of peat or organic soils. They can therefore not be considered an addition to the circumpolar peat carbon pool. We also emphasize that a clear distinction between mineral and organic soil types is important since they show very different vulnerability trajectories under climate change. Secondly, independent field data and geospatial analyses show that the Siberian Yedoma region is dominated by mineral soils, not peatlands. Thus, there is no evidence to suggest any systematic bias in the NCSCD field data or maps. Thirdly, there is spatial overlap between these Holocene thermokarst sediments and previous estimates of permafrost soil and sediment OC stocks. These carbon stocks were already accounted for by previous studies and they do not significantly increase the known circumpolar OC pool. We suggest that these inaccurate

  5. Mechanisms controlling the production and transport of methane, carbon dioxide, and dissolved solutes within a boreal peatland

    SciTech Connect

    Siegel, D.I.

    1992-04-09

    Peatlands are one of the most important terrestrial reservoirs in the global cycle for carbon, and are a major source for atmospheric methane. However, little is known about the dynamics of these carbon reservoirs or their feedback mechanisms with the pool of atmospheric CO{sub 2} during the Holocene. Specifically, it is unknown whether large peat basins are sources, sinks, or steady-state reservoirs for the global carbon cycle. In particular, the production and transport of methane, carbon dioxide, and dissolved organic carbon form the deeper portions of these peatlands is unknown. Our DOE research program is to conduct an integrated ecologic and hydrogeochemical study of the Glacial Lake Agassiz peatlands (northern Minnesota) to better understand the carbon dynamics in globally significant peat basins. Specifically, our study will provide local and regional data on (1), rates of carbon accumulation and loss and fluxes of methane in the peat profiles; (2) the physical and botanical factors controlling the production of methane and carbon dioxide in the wetland; and (3) the role of hydrogeologic processes in controlling the fluxes of gases and solutes through the peat. We intend to use computer simulation models, calibrated to field data, to scale-up from local to regional estimates of methane and carbon dioxide within the basin. How gases and dissolved organic carbon escapes form peatlands in unknown. It has been suggested that the concentrations of methane produced in the upper peat are sufficient to produce diffusion gradients towards the surface. Alternatively, gas may move through the peat profile by groundwater advection.

  6. Louis Agassiz and the Spirit of Place

    ERIC Educational Resources Information Center

    Schwarz, Jack W.

    1976-01-01

    Agassiz, one of the first great naturalists, who made significant contributions in geology, natural history, and medicine as well, is discussed with regard to his imaginative and creative teaching methods. (LBH)

  7. Responses of carbon dioxide flux and plant biomass to water table drawdown in a treed peatland in northern Alberta: a climate change perspective

    NASA Astrophysics Data System (ADS)

    Munir, T. M.; Xu, B.; Perkins, M.; Strack, M.

    2014-02-01

    Northern peatland ecosystems represent large carbon (C) stocks that are susceptible to changes such as accelerated mineralization due to water table lowering expected under a climate change scenario. During the growing seasons (1 May to 31 October) of 2011 and 2012 we monitored CO2 fluxes and plant biomass along a microtopographic gradient (hummocks-hollows) in an undisturbed dry continental boreal treed bog (control) and a nearby site that was drained (drained) in 2001. Ten years of drainage in the bog significantly increased coverage of shrubs at hummocks and lichens at hollows. Considering measured hummock coverage and including tree incremental growth, we estimate that the control site was a sink of -92 in 2011 and -70 g C m-2 in 2012, while the drained site was a source of 27 and 23 g C m-2 over the same years. We infer that, drainage-induced changes in vegetation growth led to increased biomass to counteract a portion of soil carbon losses. These results suggest that spatial variability (microtopography) and changes in vegetation community in boreal peatlands will affect how these ecosystems respond to lowered water table potentially induced by climate change.

  8. Glacial Lake Agassiz: Its northwest maximum extent and outlet in Saskatchewan (Emerson Phase)

    NASA Astrophysics Data System (ADS)

    Fisher, Timothy G.; Smith, Derald G.

    Six different lines of evidence support the hypothesis that glacial Lake Agassiz expanded an additional 70,000 km2 over that previously mapped in northwestern Saskatchewan and that the lake discharged out the northwestern (Clearwater) outlet, then through glacial Lake McConnell and Mackenzie River to the Arctic Ocean. Elevations of formerly unmapped (1) strandlines and (2) glaciolacustrine sediments between the previously mapped northwest limit of Lake Agassiz and the Clearwater-lower Athabasca spillway indicate that water extended 170 km farther northwest. Recently, mapped strandlines at elevations up to 60 m above the previously mapped extent of Lake Agassiz can be traced along (3) isobases to the mouth of the spillway. Based upon (4) six radiocarbon dates recovered from spillway flood deposits in the Athabasca River valley and its late Pleistocene delta, the (5) Clearwater spillway was cut at 9.9 ka BP. This date is synchronous with the initiation of the Emerson Phase (9.9 ka BP) in the southern Lake Agassiz basin and (6) coincides with the position of the Laurentide Ice Sheet at the Cree Lake Moraine (10 ka BP) along the northern margin of the lake. Following closure of the eastern outlets at the onset of the Emerson Phase, Lake Agassiz transgressed toward the northwest into the deglaciated and isostatically depressed glacial foreland in the Churchill River valley to an elevation of 490 m, the pre-flood elevation of the Churchill-Mackenzie drainage divide at the head of the Clearwater-lower Athabasca spillway. The Beaver River Moraine (an earthen drainage divide) was breached, resulting in lowering Lake Agassiz 52 m to a stable elevation at 438 m. The lake discharged 21,000 km3 of water into the Arctic Ocean that raised global sea level by 6 cm.

  9. Rapid deglacial and early Holocene expansion of peatlands in Alaska

    PubMed Central

    Jones, Miriam C.; Yu, Zicheng

    2010-01-01

    Northern peatlands represent one of the largest biospheric carbon (C) reservoirs; however, the role of peatlands in the global carbon cycle remains intensely debated, owing in part to the paucity of detailed regional datasets and the complexity of the role of climate, ecosystem processes, and environmental factors in controlling peatland C dynamics. Here we used detailed C accumulation data from four peatlands and a compilation of peatland initiation ages across Alaska to examine Holocene peatland dynamics and climate sensitivity. We find that 75% of dated peatlands in Alaska initiated before 8,600 years ago and that early Holocene C accumulation rates were four times higher than the rest of the Holocene. Similar rapid peatland expansion occurred in West Siberia during the Holocene thermal maximum (HTM). Our results suggest that high summer temperature and strong seasonality during the HTM in Alaska might have played a major role in causing the highest rates of C accumulation and peatland expansion. The rapid peatland expansion and C accumulation in these vast regions contributed significantly to the peak of atmospheric methane concentrations in the early Holocene. Furthermore, we find that Alaskan peatlands began expanding much earlier than peatlands in other regions, indicating an important contribution of these peatlands to the pre-Holocene increase in atmospheric methane concentrations. PMID:20368451

  10. Mechanisms controlling the production and transport of methane, carbon dioxide, and dissolved solutes within a boreal peatland. Progress report, January 15, 1991--July 14, 1992

    SciTech Connect

    Siegel, D.I.

    1992-04-09

    Peatlands are one of the most important terrestrial reservoirs in the global cycle for carbon, and are a major source for atmospheric methane. However, little is known about the dynamics of these carbon reservoirs or their feedback mechanisms with the pool of atmospheric CO{sub 2} during the Holocene. Specifically, it is unknown whether large peat basins are sources, sinks, or steady-state reservoirs for the global carbon cycle. In particular, the production and transport of methane, carbon dioxide, and dissolved organic carbon form the deeper portions of these peatlands is unknown. Our DOE research program is to conduct an integrated ecologic and hydrogeochemical study of the Glacial Lake Agassiz peatlands (northern Minnesota) to better understand the carbon dynamics in globally significant peat basins. Specifically, our study will provide local and regional data on (1), rates of carbon accumulation and loss and fluxes of methane in the peat profiles; (2) the physical and botanical factors controlling the production of methane and carbon dioxide in the wetland; and (3) the role of hydrogeologic processes in controlling the fluxes of gases and solutes through the peat. We intend to use computer simulation models, calibrated to field data, to scale-up from local to regional estimates of methane and carbon dioxide within the basin. How gases and dissolved organic carbon escapes form peatlands in unknown. It has been suggested that the concentrations of methane produced in the upper peat are sufficient to produce diffusion gradients towards the surface. Alternatively, gas may move through the peat profile by groundwater advection.

  11. Gas bubble transport and emissions for shallow peat from a northern peatland: The role of pressure changes and peat structure

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Slater, Lee

    2015-01-01

    Gas bubbles are an important pathway for methane release from peatlands. The mechanisms controlling gas bubble transport and emissions in peat remain uncertain. The effects of hydrostatic pressure and peat structure on the dynamics of gas bubbles in shallow peat were therefore tested in laboratory experiments. A peat monolith was retrieved from a raised bog and maintained in a saturated state. Three distinct layers were identified from noninvasive permittivity measurements supported by soil physical properties (porosity, bulk density). Phase I of the experiment involved monitoring for the accumulation of gas bubbles under steady pressure and temperature conditions. The data showed evidence for gas bubbles being impeded by a shallow semiconfining layer at depths between 10 and 15 cm. Visible gas bubbles observed on the side of the sample box were recorded over time to estimate changes in the vertical distribution of volumetric gas content. Porosity estimates derived using the Complex Refraction Index Model (CRIM) suggest that gas bubbles enlarge the pore space when the exerted pressure is high enough. Phase II involved triggering release of trapped bubbles by repeatedly increasing and decreasing hydrostatic pressure in an oversaturated condition. Comparison of changes in pressure head and methane density in the head space confirmed that the increasing buoyancy force during drops in pressure is more important for triggering ebullition than increasing mobility during increases in pressure. Our findings demonstrate the importance of changes in hydrostatic pressure on bubble size and variations in resistance of the peat fabric in regulating methane releases from peatlands.

  12. Detecting changes in surface moisture and water table position with spectral changes in surface vegetation in northern peatlands

    NASA Astrophysics Data System (ADS)

    Meingast, Karl M.

    Due to warmer and drier conditions, wildland fire has been increasing in extent into peatland ecosystems during recent decades. As such, there is an increasing need for broadly applicable tools to detect surface peat moisture, in order to ascertain the susceptibility of peat burning, and the vulnerability of deep peat consumption in the event of a wildfire. In this thesis, a field portable spectroradiometer was used to measure surface reflectance of two Sphagnum moss dominated peatlands. Relationships were developed correlating spectral indices to surface moisture as well as water table position. Spectral convolutions were also applied to the high resolution spectra to represent spectral sensitivity of earth observing sensors. Band ratios previously used to monitor surface moisture with these sensors were assessed. Strong relationships to surface moisture and water table position are evident for both the narrowband indices as well as broadened indices. This study also found a dependence of certain spectral relationships on changes in vegetation cover by leveraging an experimental vegetation manipulation. Results indicate broadened indices employing the 1450-1650 nm region may be less stable under changing vegetation cover than those located in the 1200 nm region.

  13. Peatland hydrogeological function at the regional scale

    NASA Astrophysics Data System (ADS)

    Larocque, M.; Avard, K.; Pellerin, S.

    2012-12-01

    Peatlands are important components of northern landscapes. In the Canadian province of Quebec, peatlands of the St. Lawrence Valley are rapidly disappearing, threatened by rapidly growing pressures from development. Peatlands are to varying extents groundwater dependent and as such are likely to respond drastically to changes in groundwater flow conditions and to contribute to the maintenance of groundwater levels within a superficial aquifer. Yet, there is very little understanding of the hydrogeological function of peatlands at the regional scale. For this reason, they are often simply discarded in complex groundwater management decisions. The implications are not clearly understood but could lead to the disruption of ecologically important fluxes and to significant impacts for the maintenance of long term water reservoirs across the land. This study was initiated in the Centre-du-Quebec region of southern Quebec to quantify how the peatland landscape has evolved in the last decades and to understand the hydrogeological function of peatlands at the regional scale. The study area (2856 km2) is located in the St. Lawrence Lowlands. The last deglaciation has contributed to a complex stratigraphy of unconsolidated sediments and peatlands have developed at the foot of the Appalachians. A recent regional study of Quaternary deposits has shown that a majority of these peatlands are found on aeolian deposits or reworked till, while only a few are set on marine clay, littoral deposits or directly on the bedrock. The area occupied by peatlands was measured with aerial photographs dating from 1966 and 2010. In 2010, peatlands were found on 6.1 % of the territory. Of these peatlands, 10 485 ha were intact and 7 015 underwent limited perturbations (e.g. drainage ditch, forest roads). Between 1966 and 2010, nearly a quarter of the peatlands observed in 1966 underwent irreversible perturbations (e.g. agriculture, paved roads). The main cause of peatland disappearance was from

  14. Spatial Variability in Biogenic Gas Dynamics in Relation to Vegetation Cover in a Northern Peatland from Ground Penetrating Radar (GPR)

    NASA Astrophysics Data System (ADS)

    Terry, N.; Slater, L. D.; Comas, X.; Mwakanyamale, K. E.; Wright, W. J.; Freeburg, Z.; Goldman, B.; Morocho, A.

    2015-12-01

    Ground penetrating radar (GPR) has been used for the last decade to investigate several aspects related to the distribution and release of biogenic gases (i.e. methane and carbon dioxide) in peat soils through well-established petrophysical relationships. We use this approach to investigate how differences in vegetation/land cover at three different field sites in Caribou Bog, Maine may alter such gas dynamics. The three study sites are characterized by: [1] a site amid standing pools of water with approximately 6 m of peat overlying an esker deposit, [2] a site dominated by low shrubs near the pools with peat down to 6.75 m, and [3] a site consisting of shrubs and trees with peat down to 6.4 m. A time-lapse series of GPR common offset (CO) and common midpoint (CMP) data were collected within hours of each other at all three sites using 100 MHz antennas during July 2013. In many cases, reciprocal data (transmitter and receiver positions switched) were also collected to gain insight on systematic errors. Water level variations and other environmental parameters were logged continuously at or near the sites, and limited gas sampling data were collected at sites [2] and [3]. Vertical 1D distributions of gas content with depth from each GPR dataset were estimated through CMP velocity analysis and application of a three component mixing model. These results were compared with CO data to observe changes in gas content along transects at each site. Preliminary results suggest site [1] (the pools site) has the highest overall gas content and exhibits the most variability in gas content through time. Despite several failed attempts to automate data acquisition in the field, manual acquisition still proves immensely valuable for quantitatively estimating spatiotemporal variability of gas content in a rapid and efficient manner in peatland ecosystems. In this case, the non-invasive monitoring of gas content variations demonstrates how free phase gas dynamics in peatlands

  15. Flow path oscillations in transient ground-water simulations of large peatland systems

    USGS Publications Warehouse

    Reeve, A.S.; Evensen, R.; Glaser, P.H.; Siegel, D.I.; Rosenberry, D.

    2006-01-01

    Transient numerical simulations of the Glacial Lake Agassiz Peatland near the Red Lakes in Northern Minnesota were constructed to evaluate observed reversals in vertical ground-water flow. Seasonal weather changes were introduced to a ground-water flow model by varying evapotranspiration and recharge over time. Vertical hydraulic reversals, driven by changes in recharge and evapotranspiration were produced in the simulated peat layer. These simulations indicate that the high specific storage associated with the peat is an important control on hydraulic reversals. Seasonally driven vertical flow is on the order of centimeters in the deep peat, suggesting that seasonal vertical advective fluxes are not significant and that ground-water flow into the deep peat likely occurs on decadal or longer time scales. Particles tracked within the ground-water flow model oscillate over time, suggesting that seasonal flow reversals will enhance vertical mixing in the peat column. The amplitude of flow path oscillations increased with increasing peat storativity, with amplitudes of about 5 cm occurring when peat specific storativity was set to about 0.05 m-1. ?? 2005 Elsevier B.V. All rights reserved.

  16. A Year in the Life: Annual Patterns of CO2 and CH4 from a Northern Finland Peatland, Including Anaerobic Methane Oxidation and Summer Ebullition Rates

    NASA Astrophysics Data System (ADS)

    Miller, K.; Lipson, D.; Biasi, C.; Dorodnikov, M.; Männistö, M.; Lai, C. T.

    2014-12-01

    The major ecological controls on methane (CH4) and carbon dioxide (CO2) fluxes in northern wetland systems are well known, yet estimates of source/sink magnitudes are often incongruous with measured rates. This mismatch persists because holistic flux datasets are rare, preventing 'whole picture' determinations of flux controls. To combat this, we measured net CO2 and CH4 fluxes from September 2012-2013 within a peatland in northern Lapland, Finland. In addition, we performed in situ manipulations and in vitro soil incubations to quantify anaerobic methane oxidation and methanogenic rates as they related to alternative electron acceptor availability. Average annual fluxes varied substantially between different depressions within the wetland, a pattern that persisted through all seasons. Season was a strong predictor of both CO2 and CH4 flux rates, yet CH4 rates were not related to melt-season 10cm or 30cm soil temperatures, and only poorly predicted with air temperatures. We found evidence for both autumnal and spring thaw CH4 bursts, collectively accounting for 26% of annual CH4 flux, although the autumnal burst was more than 5 fold larger than the spring burst. CH4 ebullition measured throughout the growing season augmented the CH4 source load by a factor of 1.5, and was linked with fine-scale spatial heterogeneity within the wetland. Surprisingly, CH4 flux rates were insensitive to Fe(III) and humic acid soil amendments, both of which amplified CO2 fluxes. Using in vitro incubations, we determined anaerobic methane oxidation and methanogenesis rates. Measured anaerobic oxidation rates showed potential consumption of between 6-39% of the methane produced, contributing approximately 1% of total carbon dioxide flux. Treatments of nitrate, sulfate and ferric iron showed that nitrate suppressed methanogenesis, but were not associated with anaerobic oxidation rates.

  17. A comparative study of within-basin and regional peatland development: implications for peatland carbon dynamics

    NASA Astrophysics Data System (ADS)

    Ireland, Alex W.; Booth, Robert K.; Hotchkiss, Sara C.; Schmitz, Jennifer E.

    2013-02-01

    Northern peatlands are among the most carbon-rich ecosystems on Earth, but many unanswered questions remain regarding linkages between their long-term developmental processes and climatic variability. In this paper, we present a detailed paleoecological reconstruction of the developmental history of a kettle peatland in northern Wisconsin, USA (Fallison Bog) based on 21 coring locations and temporally constrained by 69 radiocarbon dates. This record of within-basin developmental history is compared to a regional dataset containing estimated ages of peatland establishment for 75 core samples collected from 37 depressional peatlands throughout the Great Lakes Region. Finally, our data are used to develop a spatially explicit model of whole-system carbon accumulation in Fallison Bog, which distinguishes between carbon pools stored in limnic sediments and peat deposits. Results indicate that peatland development in Fallison Bog was episodic and spatially complex. Peatland development was related to the morphology of the underlying basin and characterized by pulses of both terrestrialization and paludification. Major episodes of terrestrialization centered on 4980 and 3180 years before A.D. 1850 (cal yr BP), with less extensive episodes occurring around 3840, 1060, 670, and 410 cal yr BP. Extensive peatland area developed by paludification of shallow portions of the basin around 2040 cal yr BP. The timing of peatland development within Fallison Bog was correlated with the timing of peatland development in other depressional peatlands across the Great Lakes Region (r = 0.70), suggesting a common climatic driver. Comparison of peatland development in Fallison Bog and independent paleoclimate records suggested that both millennial-scale and sub-centennial-scale variability in moisture balance influenced spatiotemporal patterns of peatland development. Model results indicated that Fallison Bog accumulated ˜6655 t of carbon during the Holocene, with 66% of this total stored

  18. Isotopic composition of old ground water from Lake Agassiz: Implications for late Pleistocene climate

    SciTech Connect

    Remenda, V.H.; Cherry, J.A.; Edwards, T.W.D. )

    1994-12-23

    A uniform oxygen isotope value of -25 per mil was obtained from old ground water at depths of 20 to 30 meters in a thick deposit of clay in the southern part of the glacial Lake Agassiz basin. The lake occupied parts of North Dakota and southern Manitoba at the end of the last glacial maximum and received water from the ice margin and the interior plains region of Canada. Ground water from thick late Pleistocene-age clay deposits elsewhere, a till in southern Saskatchewan, and a glaciolacustrine deposit in northern Ontario show the same value at similar depths. These sites are at about 50[degrees]N latitude, span a distance of 2000 kilometers, and like the Lake Agassiz sites, have a ground-water velocity of less than a few millimeters per year. The value of -25 per mil is characteristic of meltwater impounded in the southern basin of Lake Agassiz. This value corresponds to an estimated air temperature of -16[degrees]C, compared with the modern temperature of 0[degrees]C for this area. 15 refs., 5 figs.

  19. Methane flux from Minnesota peatlands

    SciTech Connect

    Crill, P.M.; Bartlett, K.B.; Harriss, R.C.; Gorham, E.; Verry, E.S. )

    1988-12-01

    Northern (> 40 deg N) wetlands have been suggested as the largest natural source of methane (CH{sub 4}) to the troposphere. To refine the authors estimates of source strengths from this region and to investigate climatic controls on the process, fluxes were measured from a variety of Minnesota peatlands during May, June, and August 1986. Late spring and summer fluxes ranged from 11 to 866 mg CH{sub 4}/sq/m/day, averaging 207 mg CH{sub 4} sq/m/day overall. At Marcell Forest, forested bogs and fen sites had lower fluxes than open bogs. In the Red Lake peatland, circumneutral fens, with standing water above the peat surface, produced more methane than acid bog sites in which the water table was beneath the moss surface. Peat temperature was an important control. Methane flux increased in response to increasing soil temperature. It is estimated that the methane flux from all peatlands north of 40 deg may be on the order of 70 to 90 Tg/yr though estimates of this sort are plagued by uncertainties in the areal extent of peatlands, length of the CH{sub 4} producing season, and the spatial and temporal variability of the flux. 60 refs., 7 figs., 5 tabs.

  20. Influence of permafrost thaw on carbon cycling and vegetation communities in a northern discontinuous permafrost peatland complex at Scotty Creek, Northwest Territories

    NASA Astrophysics Data System (ADS)

    Pelletier, N.; Olefeldt, D.; Turetsky, M. R.; Quinton, W. L.; Sonnentag, O.; Talbot, J.

    2013-12-01

    Globally, peatlands comprise an important proportion of the total belowground carbon pool. Peatlands in permafrost regions are usually considered as particularly important carbon sinks since their decomposition rate is slowed by the effects of low temperatures causing the ground to be frozen year-round. Discontinuous permafrost regions are particularly sensitive to contemporary climate changes causing rapid permafrost degradation with associated changes in land cover from forested permafrost peat plateaus to treeless, permafrost-free bogs. However, only little is known about the impact of these fundamental changes in land cover on peatland carbon cycling. Here we present an analysis based on peat cores collected in the late-winter of 2012 and summer 2013 in a discontinuous permafrost boreal forest-peatland complex located in the Northwest Territories, Canada. This site is known to show signs of rapid permafrost degradation over the last 40 years. Our results suggest that the hydrological changes that follow permafrost thaw might have a beneficial effect on carbon storage via changes in plant functional types. Pollen analyses performed on the same cores provide a comprehensive insight of the regional vegetation and fire dynamics over the Holocene period. Testate Amoebae analyses provide information in regards to local past hydrological conditions. Together, our results allow for a better understanding of the ways hydrology, vegetation and fire affect carbon cycling in a discontinuous permafrost peatland.

  1. Ground penetrating radar (GPR) evidence for variations in free phase carbon gas accumulation as a function of peatland landforms: a comparison between near-crest bogs and mid-slope lawns

    NASA Astrophysics Data System (ADS)

    Parsekian, A.; Slater, L.; Comas, X.; Nolan, J.; Glaser, P.

    2009-05-01

    Northern peatlands serve as atmospheric sources of biogenic free-phase gas (FPG) produced under anaerobic conditions below the water table (mostly methane and carbon dioxide). Recent evidence suggest that FPG accumulates in the subsurface under confining layers and is released during sudden ebullition events, often triggered by sudden drops in atmospheric pressure. Accurate quantification of the impact of FPG releases on the global carbon budget is needed given recent observations of increasing atmospheric methane concentrations. One important step towards understanding the dynamics of FPG in peatlands is to investigate whether certain peatland landforms (i.e. areas with significantly different vegetation patterns) may be more conducive to FPG accumulation and/or release. Additionally, it is important to determine the vertical distribution of FPG within the peat soil and the potential role of peat stratigraphy on gas accumulation and release. In this study, we used common mid-point (CMP) velocity surveys to predict vertical profiles of FPG accumulations by comparing two different peatland landforms: historically forested near-crest bogs and non- forested mid-slope lawns in the Glacial Lake Agassiz Peatland of Minnesota, USA. We show that there is a statistically significant difference in electromagnetic (EM) wave velocities calculated over gas-rich intervals in the peat strata compared to gas-poor intervals. Common-offset radar profiles identified laterally continuous woody confining layers responsible for FPG accumulation. Chaotic GPR facies containing diffraction hyperbolae at the forested near-crest sites are interpreted as deformation of the peat matrix due to FPG accumulation and/or peat fabric disturbance during FPG release events. In contrast, non-forested mid-slope lawn sites, are characterized by planar GPR facies with no evidence of peat fabric disturbance and small relative changes in interpreted EM velocity distribution along the peat column. Using the

  2. Geoelectrical properties of peat in a northern peatland: Implications for peat basin formation, vegetation patterning, pool formation, and carbon gas evaluation

    NASA Astrophysics Data System (ADS)

    Comas, Xavier

    2005-11-01

    Peatlands are unique ecosystems that represent major terrestrial stores of soil carbon. Peatlands are important sources of atmospheric methane but their response to global warming still presents major uncertainties. A better understanding of the geoelectrical properties of peat and the in-situ formation of surficial features in peatlands can improve the current knowledge of the hydrology, nutrient dynamics, stratigraphy, and biogenic gas accumulation in peatlands. Geophysical techniques and hydrological measurements at the laboratory scale are used to examine the low-frequency properties of peat. At the field scale, geophysical and hydrological data are combined to investigate peat basin formation, vegetation and pool patterning, and biogenic gas accumulations in the central unit of Caribou Bog, a peatland in central Maine. In Chapter 2, hydraulic conductivity measurements demonstrate the effect of pore dilation in peat samples, invalidating Archie's Law. An empirical model relating the resistivity and induced polarization (IP) measurements to fluid conductivity in peat is developed, and shows potential to predict pore fluid conductivity and changes in vertical hydraulic conductivity in peatlands. In Chapter 3, resistivity and surface ground penetrating radar (GPR) data suggest that underlying stratigraphy exerts a primary control on vegetation and pool patterning, and present unique evidence of the convergence of a raised bog originated in two separated basins into a single bog A conceptual model for basin formation and peatland development in Caribou Bog is presented. In Chapter 4, surface GPR and terrain conductivity (EM31) surveys combined with direct core sampling indicate correlation between the location of open pools and elevated mineral soil surfaces (interpreted as esker deposits). A conceptual model based on a beaded esker system containing multiple ridges is developed to explain the formation of pools in Caribou Bog. In Chapter 5, areas of EM wave

  3. Ice - not just H2O (Louis Agassiz Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Wolff, E. W.

    2009-04-01

    Many of the important properties and uses of ice that fascinate cryospheric scientists actually depend on impurities that are present: isotopic variants of water molecules, small amounts of soluble and insoluble material derived from the aerosol and gas phase, and the trace constituents of the air bubbles that make up around 10% of the volume of ice at atmospheric pressure. In this lecture, I will first discuss how these impurities, and their location within the ice structure, affect local properties of the ice such as the electrical conductivity and mechanical strength, which scale up to give ice sheets their geophysical properties. I will then consider how the concentrations of different impurities are used to give unique records of palaeoclimate and palaeoenvironmental properties, extending so far 800,000 years back in time. This will be illustrated particularly with data from the EPICA Dome C ice core. Bringing the presentation full circle (and towards Agassiz!), I will discuss how the data from ice cores and other palaeoclimatic archives are starting to lead us towards understanding of the causes of the most prominent feature of late Quaternary climate: the huge glacial/interglacial swings in temperature, that are accompanied by the waxing and waning, roughly every 100,000 years, of great northern hemisphere ice sheets.

  4. Carbon isotopes as indicators of peatland growth?

    NASA Astrophysics Data System (ADS)

    Alewell, Christine; Krüger, Jan Paul; von Sengbusch, Pascal; Szidat, Sönke; Leifeld, Jens

    2016-04-01

    As undisturbed and/or growing peatlands store considerable amounts of carbon and are unique in their biodiversity and species assemblage, the knowledge of the current status of peatlands (growing with carbon sequestration, stagnating or degrading with carbon emissions) is crucial for landscape management and nature conservation. However, monitoring of peatland status requires long term measurements and is only feasible with expert knowledge. The latter determination is increasingly impeded in a scientific world, where taxonomic expert knowledge and funding of long term monitoring is rare. Stable carbon and nitrogen isotopes depth profiles in peatland soils have been shown to be a useful tool to monitor the degradation of peatlands due to permafrost thawing in Northern Sweden (Alewell et al., 2011; Krüger et al., 2014), drainage in Southern Finland (Krüger et al., 2016) as well as land use intensification in Northern Germany (Krüger et al., 2015). Here, we tackle the questions if we are able to differentiate between growing and degrading peats with the use of a combination of carbon stable (δ13C) and radiogenic isotope data (14C) with peat stratification information (degree of humification and macroscopic plant remains). Results indicate that isotope data are a useful tool to approximate peatland status, but that expert taxonomic knowledge will be needed for the final conclusion on peatland growth. Thus, isotope tools might be used for landscape screening to pin point sites for detailed taxonomic monitoring. As the method remains qualitative future research at these sites will need to integrate quantitative approaches to determine carbon loss or gain (soil C balances by ash content or C accumulation methods by radiocarbon data; Krüger et al., 2016). Alewell, C., R. Giesler, J. Klaminder, J. Leifeld, and M. Rollog. 2011. Stable carbon isotopes as indicators for micro-geomorphic changes in palsa peats. Biogeosciences, 8, 1769-1778. Krüger, J. P., Leifeld, J

  5. A 9000 year perspective on carbon accumulation rates under changing hydro-climate and vegetation conditions in a mountain peatland, northern Carpathians, Romania

    NASA Astrophysics Data System (ADS)

    Feurdean, Angelica; Panait, Andrei; Gałka, Mariusz; Diaconu, Andrei; Hutchinson, Simon; Mulch, Andreas; Tantau, Ioan; Hickler, Thomas

    2016-04-01

    Peatlands, in particular ombrogenous bogs, which entirely depend on water from precipitation, are sensitive to changes in the balance between precipitation and evapotranspiration; and therefore highly suitable for hydro-climatological reconstruction. Peatlands also represent a large carbon pool in the terrestrial biosphere. However, little is known about the C sequestration processes in mountain peatlands under various competing drivers of change (climate, vegetation, fire). We applied a multi-proxy approach (bulk density, loss on ignition, total organic carbon, testate amoebae, δ13C in Sphagnum, plant macrofossils, pollen and charcoal) to a peat sequence from a mountain ombrogenous bog (Tǎul Muced) to explore how changes in hydro-climate conditions, peat plant composition and fire have affected long-term physical peat properties and the rate of carbon accumulation over the last 9000 years. Carbon accumulation at this site ranged from 7 to 105 g C cm2 yr1 (mean 23 ± 14 g C cm2 yr_1). We found that high moisture availability (P-E) as inferred from testate amoebae and δ13C values in Sphagnum increased the carbon sink capacity of peatland. The strength of the relationship between the rate of carbon accumulation and climate appears particularly evident over the last millennium when high C accumulation rates correlated with the warm and wet conditions of the Medieval Climate Anomaly and lower C accumulation rates with the dry conditions of the Little Ice Age. We also found a significant positive correlation between the rate of C accumulation and changes in vegetation; rates were lowest (17 g C cm2 yr_1), during periods of mixed Sphagnum (primarily S. magellanicum and S. angustifolium) and vascular plant (Cyperaceae, Eriophorum vaginatum) growth and increased (31 g C cm2 yr_1) during the accumulation of Sphagnum peat, regardless the dominant Sphagnum species. We did not find indication of peatland fire during the investigated interval. Our study represents one of the

  6. Moderate drop in water table increases peatland vulnerability to post-fire regime shift

    NASA Astrophysics Data System (ADS)

    Kettridge, N.; Turetsky, M. R.; Sherwood, J. H.; Thompson, D. K.; Miller, C. A.; Benscoter, B. W.; Flannigan, M. D.; Wotton, B. M.; Waddington, J. M.

    2015-01-01

    Northern and tropical peatlands represent a globally significant carbon reserve accumulated over thousands of years of waterlogged conditions. It is unclear whether moderate drying predicted for northern peatlands will stimulate burning and carbon losses as has occurred in their smaller tropical counterparts where the carbon legacy has been destabilized due to severe drainage and deep peat fires. Capitalizing on a unique long-term experiment, we quantify the post-wildfire recovery of a northern peatland subjected to decadal drainage. We show that the moderate drop in water table position predicted for most northern regions triggers a shift in vegetation composition previously observed within only severely disturbed tropical peatlands. The combined impact of moderate drainage followed by wildfire converted the low productivity, moss-dominated peatland to a non-carbon accumulating shrub-grass ecosystem. This new ecosystem is likely to experience a low intensity, high frequency wildfire regime, which will further deplete the legacy of stored peat carbon.

  7. Moderate drop in water table increases peatland vulnerability to post-fire regime shift

    PubMed Central

    Kettridge, N.; Turetsky, M. R.; Sherwood, J. H.; Thompson, D. K.; Miller, C. A.; Benscoter, B. W.; Flannigan, M. D.; Wotton, B. M.; Waddington, J. M.

    2015-01-01

    Northern and tropical peatlands represent a globally significant carbon reserve accumulated over thousands of years of waterlogged conditions. It is unclear whether moderate drying predicted for northern peatlands will stimulate burning and carbon losses as has occurred in their smaller tropical counterparts where the carbon legacy has been destabilized due to severe drainage and deep peat fires. Capitalizing on a unique long-term experiment, we quantify the post-wildfire recovery of a northern peatland subjected to decadal drainage. We show that the moderate drop in water table position predicted for most northern regions triggers a shift in vegetation composition previously observed within only severely disturbed tropical peatlands. The combined impact of moderate drainage followed by wildfire converted the low productivity, moss-dominated peatland to a non-carbon accumulating shrub-grass ecosystem. This new ecosystem is likely to experience a low intensity, high frequency wildfire regime, which will further deplete the legacy of stored peat carbon. PMID:25623290

  8. Moderate drop in water table increases peatland vulnerability to post-fire regime shift.

    PubMed

    Kettridge, N; Turetsky, M R; Sherwood, J H; Thompson, D K; Miller, C A; Benscoter, B W; Flannigan, M D; Wotton, B M; Waddington, J M

    2015-01-01

    Northern and tropical peatlands represent a globally significant carbon reserve accumulated over thousands of years of waterlogged conditions. It is unclear whether moderate drying predicted for northern peatlands will stimulate burning and carbon losses as has occurred in their smaller tropical counterparts where the carbon legacy has been destabilized due to severe drainage and deep peat fires. Capitalizing on a unique long-term experiment, we quantify the post-wildfire recovery of a northern peatland subjected to decadal drainage. We show that the moderate drop in water table position predicted for most northern regions triggers a shift in vegetation composition previously observed within only severely disturbed tropical peatlands. The combined impact of moderate drainage followed by wildfire converted the low productivity, moss-dominated peatland to a non-carbon accumulating shrub-grass ecosystem. This new ecosystem is likely to experience a low intensity, high frequency wildfire regime, which will further deplete the legacy of stored peat carbon. PMID:25623290

  9. Bedrock topography beneath the Red Lake peatlands

    SciTech Connect

    Miller, P.; Shaw, G.H. . Geology Dept.); Glaser, P. . Limnological Research Center); Siegel, D. . Dept. of Geology)

    1992-01-01

    Detailed hydrologic investigations of peat landforms in the Red Lake Peatlands have revealed that groundwater flow is significantly related to the type of landform and vegetation community present at a given site. Hydrogeologic modeling of shallow groundwater systems suggests that bedrock topography is an important, perhaps the vital, boundary condition controlling groundwater flow. Determination of depth to bedrock beneath different peat landforms is necessary to test the hydrogeologic models and obtain a better understanding of the processes which produce them. Direct determination of bedrock depth in peatlands is hampered by the difficult conditions and high costs of boring. In addition, environmental impacts from boring activities would probably be substantial in these sensitive ecosystems. Shallow seismic methods appear to be the most promising approach to obtain the necessary data. Unfortunately the 2+ meters of peat covering Lake Agassiz sediments overlying the bedrock is not only a poor substrate for geophone emplacement, but is a strong attenuator of seismic waves. These difficulties have been overcome by constructing a tool which allows the geophones to be emplaced beneath the peat and into the top of the sediments. The shotgun cartridge source is also located beneath the peat. This combination results in very good seismic records, far better than those possible with surface sources and geophones. The results from a preliminary survey along a 600m line show that there are significant variations in bedrock topography below the peat. In a distance of less than 500m, depth to bedrock changes by about 30%, from about 55m to about 40m. This is similar to variations indicated by the models.

  10. Quantifying landscape morphology influence on peatland lateral expansion using ground-penetrating radar (GPR) and peat core analysis

    NASA Astrophysics Data System (ADS)

    Loisel, Julie; Yu, Zicheng; Parsekian, Andrew; Nolan, James; Slater, Lee

    2013-06-01

    peatlands contain vast amounts of organic carbon. Large-scale datasets have documented spatial patterns of peatland initiation as well as vertical peat accumulation rates. However, the rate, pattern, and timing of lateral expansion across the northern landscape remain largely unknown. As peatland lateral extent is a key boundary condition constraining the dynamics of peatland systems, understanding this process is essential. Here we use ground penetrating radar (GPR) and peat core analysis to study the effect of local slope and topography on peatland development at a site in south-central Alaska. The study site is unique in that a thick tephra (volcanic ash) layer, visible in the GPR data, interrupted the peatland development for about one thousand years during the mid Holocene. In our analysis, this tephra layer serves as a re-initiation point for peatland development. By comparing the initial mineral basin vs. the post-tephra surfaces, the influence of topography and slope on peatland expansion rate and peat-carbon sequestration was analyzed. Our results show that (1) peatland surface slope becomes progressively shallower over the Holocene, (2) slope affects peatland lateral expansion nonlinearly, (3) the relationship between lateral expansion rate and slope follows a power-law behavior, and (4) peatland expansion becomes slope-limited above a threshold (0.5°). Furthermore, we propose a conceptual model linking slope to peatland lateral expansion where slope gradient and basin topography exert deterministic controls on peatland lateral expansion directly or through hydrology and vertical accumulation rates.

  11. Vascular plants promote ancient peatland carbon loss with climate warming.

    PubMed

    Walker, Tom N; Garnett, Mark H; Ward, Susan E; Oakley, Simon; Bardgett, Richard D; Ostle, Nicholas J

    2016-05-01

    Northern peatlands have accumulated one third of the Earth's soil carbon stock since the last Ice Age. Rapid warming across northern biomes threatens to accelerate rates of peatland ecosystem respiration. Despite compensatory increases in net primary production, greater ecosystem respiration could signal the release of ancient, century- to millennia-old carbon from the peatland organic matter stock. Warming has already been shown to promote ancient peatland carbon release, but, despite the key role of vegetation in carbon dynamics, little is known about how plants influence the source of peatland ecosystem respiration. Here, we address this issue using in situ (14)C measurements of ecosystem respiration on an established peatland warming and vegetation manipulation experiment. Results show that warming of approximately 1 °C promotes respiration of ancient peatland carbon (up to 2100 years old) when dwarf-shrubs or graminoids are present, an effect not observed when only bryophytes are present. We demonstrate that warming likely promotes ancient peatland carbon release via its control over organic inputs from vascular plants. Our findings suggest that dwarf-shrubs and graminoids prime microbial decomposition of previously 'locked-up' organic matter from potentially deep in the peat profile, facilitating liberation of ancient carbon as CO2. Furthermore, such plant-induced peat respiration could contribute up to 40% of ecosystem CO2 emissions. If consistent across other subarctic and arctic ecosystems, this represents a considerable fraction of ecosystem respiration that is currently not acknowledged by global carbon cycle models. Ultimately, greater contribution of ancient carbon to ecosystem respiration may signal the loss of a previously stable peatland carbon pool, creating potential feedbacks to future climate change. PMID:26730448

  12. Evidence of a 700-year Lake Agassiz megaflood in the slackwater deposits of Mississippi River tributaries

    NASA Astrophysics Data System (ADS)

    Wang, H.; Stumpf, A.; Berg, R. C.; McKay, E. D., III

    2010-12-01

    One prominent event associated with retreat of the Laurentide Ice Sheet was the release of an exceptionally large volume of meltwater from Lake Agassiz. This discharge led to a sea-level rise of 20 meters in about 500 years and caused disruption to the global thermohaline circulation that led to an overall cooling during the Younger Dryas stadial (YDS). Recent studies suggest that the eastern and northern outlets of glacial Lake Agassiz remained closed until the early YDS, but new findings by the authors indicate that catastrophic floods drained through a southern outlet along the Mississippi River at this time. Here we present a detailed description of a dune-paleosol/peat succession from the middle Illinois River valley containing a slackwater deposit (peat) associated with these floods that has been dated using 14C and OSL methods to the Bølling-Allerød interstadial. At this site, Heinrich stadial 1 (HS1) and YDS dunes are separated by a well-developed Bølling-equivalent paleosol overlain by an Allerød-equivalent slackwater peat unit. The paleosol developed under warm/humid conditions, fundamentally different from the cold and dry conditions that prevailed during dune formation. Our age model indicates that the Bølling-equivalent paleosol developed for 1200 years followed by the meltwater megaflood. Preliminary measurements indicate the flood raised the Mississippi River level at its juncture with the Illinois River 18 m higher than the 500-year flood recorded in 1993. The megaflood blocked the Illinois River forming a large slackwater swamp, which lasted for 700 years. The release of cold meltwater through the Mississippi River basin inevitably lowered the sea surface temperature (SST) in the Gulf of Mexico, shortening the northern overturning circulation and shifting the Intertropical Convergence Zone (ITCZ) southward. As a consequence, the southerlies became weakened and retreated southward allowing the dry westerlies and northwesterlies to carry Pacific

  13. Exploring Spatiotemporal Patterns of Holocene Carbon Dynamics in Northern Peatlands by Incorporating Bayesian Age-Depth Modeling into Monte-Carlo EOF Analysis

    NASA Astrophysics Data System (ADS)

    Massa, Charly; Yu, Zicheng; Blaauw, Maarten; Loisel, Julie

    2014-05-01

    EOF (Empirical Orthogonal Functions) analysis is a common tool for exploring the spatiotemporal modes of instrumental climate data. Although rarely applied to paleo proxy records, the EOF method is an efficient tool for the detection and analysis of broad-scale patterns of centennial to millennial-scale climate variability. But most paleoclimate records are not annually resolved and have inherent chronological uncertainties that may be problematic using ordinary EOF. Anchukaitis et al. (2012) provided a major step forward in paleo proxy data analysis by adapting EOF to time-uncertain paleoclimate proxy records (Monte-Carlo EOF). However, additional problems may arise for analyzing flux-based paleo parameters, such as peat C accumulation rates, which are strongly dependent to age-depth modeling, that is, small uncertainties in ages may lead to large differences in accumulation rates. Here we present a new approach that combines Bayesian age modeling and Monte-Carlo EOF to analyze flux-based paleo-datasets by thoroughly addressing both chronological and flux measurement uncertainties. This approach, implemented as a suit of linked R functions, overcomes a number of technical challenges, such as the effective handling of large datasets, the reduction of computational requirements for calculating hundreds of thousands of iterations, standardization issues, and EOF computation of gappy data. As a case study we explored the recently published Holocene circum-Arctic peatland database with >100 sites (Loisel et al. in press) to investigate the spatiotemporal patterns and climate controls of peat C accumulation. The approach can be used for other flux-based proxies, such as charcoal influx, erosion rates or atmospheric depositions. Our preliminary results reveal different temporal patterns of C accumulation in major peatland regions, as controlled by various regional climate histories and other bioclimatic factors. For instance, peatlands in continental vs. oceanic settings

  14. CO2 and CH4 Net Carbon Flux from a high-carbon peatland in Northern Minnesota: Plot scale observations of the Shrub, forb, Sphagnum and microbial community

    NASA Astrophysics Data System (ADS)

    Phillips, J. R.; Hanson, P. J.; Riggs, J.

    2013-12-01

    Significant uncertainty exists regarding the fate of stored peatland carbon under future climate warming scenarios. Methods have been developed to track net flux of CO2 and CH4 from experimental warming plots at a scale appropriate to the in situ biological community. Surface flux measurements of CO2 and CH4 were made using and open-path analyzers over and area of 1.13 m2 within each of our 16 plots. A custom-designed chamber encloses the hummock-hollow topography and allows point in time measurements of the shrub, forb, Sphagnum and the complex microbial community complex. These observations are made with ambient light and imposed dark conditions to allow estimates of net community daytime and night respiratory processes. Sphagnum hollow temperatures, water table levels, hummock moisture levels, and recent PAR as a potential surrogate for labile C are all being evaluated as drivers of net CO2-C and CH4-C flux. Periodic observations from August 2011 through July 2013 show obvious seasonal trends with temperature being the obvious driving variable. During this ';wet' time period surface drying and lower water table depths have not been seen to be key drivers of net C flux. Midwinter conditions with a frozen peat surface produce zero CO2 and CH4 flux. Maximum net CO2 flux in mid summer shows daytime surface uptake values near -6 to -7 μmol m-2 s-1 and night loss rates of 6 to 7 μmol m-2 s-1. Maximum midsummer observed CH4 flux for this bog range from 0.4 to 0.5 μmol m-2 s-1. Integrating temperature dependent models of net flux across annual periods showed next CO2-C and net CH4-C flux to be 850 and 20 g C m-2 y-1, respectively. Sequential clipping of vegetation layers showed that the shrub (LAI = ~0.5 m2 m-2) and the forb/sedge layer (LAI = ~1 m2 m-2) dominated net carbon uptake during daytime periods while shading the Sphagnum layer (LAI >1 m2 m-2), but had limited impact on dark community respiration likely dominated by the subsurface microbial community. A

  15. Creating Original Opera at Lake Agassiz Elementary School.

    ERIC Educational Resources Information Center

    Sherwood, Connie; And Others

    1994-01-01

    In 1993 Lake Agassiz School in North Dakota received a Knight Foundation grant so teachers and students could participate in a program to learn how to create an opera. The program instructed teachers on how students could maximize their understanding about producing an opera. The school formed a partnership with the Metropolitan Opera Guild of New…

  16. Mechanisms controlling the production and transport of methane, carbon dioxide, and dissolved solutes within a boreal peatland. Progress report, July 15, 1992--July 14, 1993

    SciTech Connect

    Siegel, D.I.

    1993-06-24

    The role of freshwater peatlands in the global methane cycle remains uncertain. Field measurements of methane emissions tend to be highly variable across a peatland and exhibit sharp seasonal fluctuations. The process of extrapolating these variable measurements to regional estimates is further complicated by rudimentary knowledge of the environmental controls can the production and emissions of methane from peat. The distribution of methanogenesis within the peat profile will strongly influence the response of methane emissions to potential climatic changes. During the summers of 1990 and 1991 we conducted a study on the mechanisms for the production, transport, and storage of methane within the Glacial Lake Agassiz peatland region as the regional climate shifted from extreme drought to a period of normal rainfall. This natural experiment provided unexpected insights on the linkages among climate, hydrology, and the methane cycle in large peat basins. This report presents project progress for period July 15, 1992--July 14, 1993

  17. Exploring the limits of knowledge on boreal peatland development using a new model: the Holocene Peatland Model

    NASA Astrophysics Data System (ADS)

    Quillet, Anne; Garneau, Michelle; Frolking, Steve; Roulet, Nigel; Peng, Changhui

    2010-05-01

    's assemblage of current knowledge. Second, the importance of some parameters on simulation results points out certain gaps in the current understanding of peatland dynamics. Thus, this study helps determine some avenues that should be explored in future in order to improve peatlands dynamics understanding. Frolking S, NT Roulet, A Quillet, E Tuittila, JL Bubier. 2009. Simulating long-term carbon and water dynamics in northern peatlands Eos Trans. AGU, 90(52), Fall Meet. Suppl., Abstract PP12B-05. Frolking S, NT Roulet, E Tuittila, JL Bubier, A Quillet. XXXX. A new model of Holocene peatland net primary production, decomposition, and peat accumulation. in prep. Ziehn T, AS Tomlin. 2009. GUI-HDMR - A solftware tool for global sensitivity analysis of complex models. Environmental Modelling & Software, 24, 775-785.

  18. Late Pleistocene Palaeoenvironments of the Southern Lake Agassiz Basin, USA

    NASA Astrophysics Data System (ADS)

    Yansa, Catherine H.; Ashworth, Allan C.

    2005-03-01

    Macroscopic plant remains, pollen, insect and mollusc fossils recovered from a cut bank on the Red River in North Dakota, USA, provide evidence that an extensive wetland occupied the southern basin of Lake Agassiz from 10 230 to 9900 14C yr BP. Marsh-dwelling plants and invertebrates had colonised the surface of a prograding delta during the low-water Moorhead Phase of Lake Agassiz. A species of Salix (willow) was abundant along distributary channels, and stands of Populus tremuloides (aspen), Ulmus sp. (elm), Betula sp. (birch), and Picea sp. (spruce) grew on the better-drained sand bars and beach ridges. Most of the species of plants, insects, and molluscs represented as fossils are within their existing geographic ranges. Based on a few species with more northerly distributions, mean summer temperature may have been about 1-2°C lower than the present day. No change in species composition occurred in the transition from the Younger Dryas to Preboreal. At the time that the wetland existed, Lake Agassiz was draining either eastward to the North Atlantic Ocean or northwestward to the Arctic Ocean. The wetland was drowned during the Emerson Phase transgression that resulted in meltwater draining southward to the Gulf of Mexico after 9900 14C yr BP.

  19. Processes responding to restoration in forestry-drained peatlands

    NASA Astrophysics Data System (ADS)

    Tarvainen, Oili; Laine, Anna; Tolvanen, Anne

    2014-05-01

    Almost one third, nearly 100 000 km2, of the total land area is covered by peatlands in Finland, which is a higher relative cover than in any other country in the world. Over a half of the peatland area has been drained for forestry, and many invaluable wetland habitat types are severely degraded. Restoration of forestry-drained peatlands is a relatively new measure, and long term results are still relatively scarce. Reinstating the ecological function with its feedback cycles can be a slow and gradual process. Nevertheless, since forestry-drained peatlands are not destroyed habitats in terms of their ecosystem functions, they can be expected to be reinstated through the returning of the crucial element, the high water-table level and its natural variability. To evaluate the development of peatland function and structure after restoration, indicators which respond at different speed to restoration are therefore useful. Vegetation indicators are commonly assessed to indicate restoration progress, but they can be slow to respond. Changes in the mineralization and decomposition rates may indicate sooner, if processes typical for undrained peatlands are initiating after restoration. However, despite the increasing amount of information on the vegetation structure after restoring forestry-drained peatlands, there is no sufficient information on the ecological processes, which may be reasons behind the existing difference between restored and pristine peatlands. Information on the ecological processes and the speed of their recovery helps to evaluate whether the restored peatlands have turned their development towards natural situation, despite that the structure does not yet show sufficient recovery. We studied how restoration affects the hydrology, peat forming processes, and vegetation in boreal fen type of peatlands. Fens drained for forestry 30 - 40 year earlier were restored in northern Finland in 2007 by harvesting trees and by damming and filling ditches. After

  20. Peatland Carbon Dynamics in Alaska During Past Warm Climates

    NASA Astrophysics Data System (ADS)

    Yu, Z.; Cleary, K.; Massa, C.; Hunt, S. J.; Klein, E. S.; Loisel, J.

    2013-12-01

    and colder winters, also reducing non-growing season decomposition. Reduced summer sea ice cover would also mediate and increase summer temperatures on the North Slope. Overall, our results show that, contrary to conventional wisdom, cool and wet climates such as those that characterized the Neoglacial period may result in peatland flooding (too much water), thereby limiting peat accumulation in these wet and cold regions. If the observations from northern Alaska are also applicable to other high-latitude regions with possible 'disappeared peatlands', our findings have important implications for understanding the role of peatlands in the global C cycle in the past and future.

  1. Carbon accumulation of tropical peatlands over millennia: a modeling approach.

    PubMed

    Kurnianto, Sofyan; Warren, Matthew; Talbot, Julie; Kauffman, Boone; Murdiyarso, Daniel; Frolking, Steve

    2015-01-01

    Tropical peatlands cover an estimated 440,000 km2 (~10% of global peatland area) and are significant in the global carbon cycle by storing about 40-90 Gt C in peat. Over the past several decades, tropical peatlands have experienced high rates of deforestation and conversion, which is often associated with lowering the water table and peat burning, releasing large amounts of carbon stored in peat to the atmosphere. We present the first model of long-term carbon accumulation in tropical peatlands by modifying the Holocene Peat Model (HPM), which has been successfully applied to northern temperate peatlands. Tropical HPM (HPMTrop) is a one-dimensional, nonlinear, dynamic model with a monthly time step that simulates peat mass remaining in annual peat cohorts over millennia as a balance between monthly vegetation inputs (litter) and monthly decomposition. Key model parameters were based on published data on vegetation characteristics, including net primary production partitioned into leaves, wood, and roots; and initial litter decomposition rates. HPMTrop outputs are generally consistent with field observations from Indonesia. Simulated long-term carbon accumulation rates for 11,000-year-old inland, and 5000-year-old coastal peatlands were about 0.3 and 0.59 Mg C ha(-1) yr(-1), and the resulting peat carbon stocks at the end of the 11,000-year and 5000-year simulations were 3300 and 2900 Mg C ha(-1), respectively. The simulated carbon loss caused by coastal peat swamp forest conversion into oil palm plantation with periodic burning was 1400 Mg C ha(-1) over 100 years, which is equivalent to ~2900 years of C accumulation in a hectare of coastal peatlands. PMID:25044171

  2. Peatlands as Dynamic Biogeochemical Ecotones: Elemental Concentrations, Stoichiometries and Accumulation in Peatland Soils of Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Moore, T. R.; Wang, M.; Talbot, J.; Riley, J. L.

    2015-12-01

    Peatlands act as biogeochemical interfaces between terrestrial and aquatic systems and are 'hotspots', particularly for carbon cycling and the accumulation of nutrients and other elements within the peat profile. This results in storage of substantial amounts of carbon, nutrients and metals, particularly in northern peatlands. Using a data base of over 400 peat profiles and 1700 individual peat samples from bog, fen and swamp sites in Ontario, Canada, we examine the profile concentrations of C, N, P, Ca, Mg, K, Hg, Pb, As, Cu, Mn, Zn, Fe and Al, and estimate the storage and accumulation of these elements. We show how these profiles, spatial patterns, stoichiometries and accumulation rates are controlled by biogeochemical processes and influenced by geochemical setting, hydrology, atmospheric input and pollution, and ecological and microbial transformations.

  3. In the line of fire: the peatlands of Southeast Asia.

    PubMed

    Page, S E; Hooijer, A

    2016-06-01

    Peatlands are a significant component of the global carbon (C) cycle, yet despite their role as a long-term C sink throughout the Holocene, they are increasingly vulnerable to destabilization. Nowhere is this shift from sink to source happening more rapidly than in Southeast Asia, and nowhere else are the combined pressures of land-use change and fire on peatland ecosystem C dynamics more evident nor the consequences more apparent. This review focuses on the peatlands of this region, tracing the link between deforestation and drainage and accelerating C emissions arising from peat mineralization and fire. It focuses on the implications of the recent increase in fire occurrence for air quality, human health, ecosystem resilience and the global C cycle. The scale and controls on peat-driven C emissions are addressed, noting that although fires cause large, temporary peaks in C flux to the atmosphere, year-round emissions from peat mineralization are of a similar magnitude. The review concludes by advocating land management options to reduce future fire risk as part of wider peatland management strategies, while also proposing that this region's peat fire dynamic could become increasingly relevant to northern peatlands in a warming world.This article is part of the themed issue 'The interaction of fire and mankind'. PMID:27216508

  4. Sources and Age of Aquatic DOC, CO2 And CH4 Exported From a Swedish Peatland

    NASA Astrophysics Data System (ADS)

    Campeau, A.; Wallin, M.; Billett, M. F.; Nilsson, M. B.; Laudon, H.; Oquist, M. G.; Bishop, K. H.

    2015-12-01

    Northern peatlands store as much organic matter as the equivalent of all the CO2 currently present in the earth's atmosphere. The peat carbon storage results from the progressive accumulation of organic matter since the end of the last glaciation (~10 000 years). The stability of these large carbon storages, under the influence of climate change, is unknown. Runoff represents one of the major C fluxes out of northern peatlands, and is particularly sensitive to changes in climate and hydrological regimes. Identifying the sources and age of aquatic C export will help assess the stability and future role of northern peatlands as active components of the global C cycle. We have characterized both radiogenic (14C) and stable carbon isotopes (δ13C) of DOC, CO2 and CH4 across a four-meter deep ombrotrophic peatland and its stream outlet. Previous studies have shown that about 34% of the estimated net ecosystem exchange from this peatland system, is lost through aquatic C export. We determined that fermentation processes in the peat acts as the main production pathway for stream CO2 (mean δ13C =-4.9‰) and CH4 (mean δ13C = -67.8‰). The seasonal variability in both sources and age of C was high. Despite this dynamism, the application of carbon isotopes allowed us to trace back the origin of aquatic C exports from the peatland.

  5. Sobol' sensitivity analysis of the Holocene Peat Model: What drives carbon accumulation in peatlands?

    NASA Astrophysics Data System (ADS)

    Quillet, Anne; Garneau, Michelle; Frolking, Steve

    2013-03-01

    Understanding the development of northern peatlands and their carbon accumulation dynamics is crucial in order to confidently integrate northern peatlands into global carbon cycle models. To achieve this, northern peatland models are becoming increasingly complex and now include feedback processes between peat depth, decomposition, hydrology, and vegetation composition and productivity. Here we present results from a global sensitivity analysis performed to assess the behavior and parameter interaction of a peatland simulation model. A series of simulations of the Holocene Peat Model were performed with different parameter combinations in order to assess the role of parameter interactions on the simulated total carbon mass after 5000 years of peatland development. The impact of parameter uncertainty on the simulation results is highlighted, as is the importance of multiple parameter interactions. The model sensitivity indicates that peat physical properties play an important role in peat accumulation; these parameters are poorly constrained by observations and should be a focus of future research. Furthermore, the results show that autogenic processes are able to produce a wide range of peatland development behaviors independently of any external environmental changes.

  6. Ecohydrology by thinking outside the bog: Shifting paradigms in an era of shifting peatland ecosystems

    NASA Astrophysics Data System (ADS)

    Waddington, James; Moore, Paul

    2016-04-01

    Large shifts in vegetation distributions are occurring worldwide and at unprecedented rates. The most extreme of these regime shifts are expected to occur at ecosystem boundaries of both semi-arid and semi-humid landscapes. Despite extensive hydrological research on the interactions between water and semi-arid ecosystems, research in peatlands on the wet end of ecosystem continuum has been "bogged down" (pun fully intended) by the traditional conceptual models (paradigms?) of peatland hydrology and ecology. The consequences of this "thinking" are large given that northern peatlands provide important global and regional ecosystem services (carbon storage, water storage, and biodiversity). This is especially true because peatlands face increases in the severity, areal extent, and frequency of climate-mediated (e.g., wildfire, drought) and land-use change (e.g., drainage, flooding, and mining) disturbances placing the future security of these critical ecosystem services in doubt. We use the word doubt because while numerical modelling studies predict peatland regime shifts and the demise of global peat stocks, there is growing evidence that peatlands are self-regulating ecosystems dominated by negative ecohydrological feedbacks that stabilize the aforementioned ecosystem services through high ecosystem resilience to disturbance. This raises several important hydrological questions? "Is there field evidence of peatland regime shifts? If so, what are the potential impacts of these shifts on water resources and watershed management? If not, are researchers actually looking in the right places (or times)? In this presentation we explore the need for a "thinking outside the bog" in order to understand the ecohydrological consequences of transformative landscape change caused by peatland regime shifts. With reference to over two decades of field research, recent advances with our Peatland Hydrological Impacts model and recent research examining primary peat formation, we

  7. The effects of hydrologic fluctuation and sulfate regeneration on mercury cycling in an experimental peatland

    NASA Astrophysics Data System (ADS)

    Coleman Wasik, J. K.; Engstrom, D. R.; Mitchell, C. P. J.; Swain, E. B.; Monson, B. A.; Balogh, S. J.; Jeremiason, J. D.; Branfireun, B. A.; Kolka, R. K.; Almendinger, J. E.

    2015-09-01

    A series of severe droughts during the course of a long-term, atmospheric sulfate-deposition experiment in a boreal peatland in northern Minnesota created a unique opportunity to study how methylmercury (MeHg) production responds to drying and rewetting events in peatlands under variable levels of sulfate loading. Peat oxidation during extended dry periods mobilized sulfate, MeHg, and total mercury (HgT) to peatland pore waters during rewetting events. Pore water sulfate concentrations were inversely related to antecedent moisture conditions and proportional to past and current levels of atmospheric sulfate deposition. Severe drying events caused oxidative release of MeHg to pore waters and resulted in increased net MeHg production likely because available sulfate stimulated the activity of sulfate-reducing bacteria, an important group of Hg-methylating bacteria in peatlands. Rewetting events led to increased MeHg concentrations across the peatland, but concentrations were highest in peat receiving elevated atmospheric sulfate deposition. Dissolved HgT concentrations also increased in peatland pore waters following drought but were not affected by sulfate loading and did not appear to be directly controlled by dissolved organic carbon mobilization to peatland pore waters. Peatlands are often considered to be sinks for sulfate and HgT in the landscape and sources of MeHg. Hydrologic fluctuations not only serve to release previously sequestered sulfate and HgT from peatlands but may also increase the strength of peatlands as sources of MeHg to downstream aquatic systems, particularly in regions that have experienced elevated levels of atmospheric sulfate deposition.

  8. Systematics and ecology of the Australasian genus Empodisma (Restionaceae) and description of a new species from peatlands in northern New Zealand

    PubMed Central

    Wagstaff, Steven J.; Clarkson, Beverley R.

    2012-01-01

    Abstract The genus Empodisma comprises two species that are ecologically important in wetland habitats. Empodisma gracillimum is restricted to south-western Australia, whereas Empodisma minus is found in Tasmania, eastern Australia and New Zealand. We sequenced three cpDNA genes for 15 individuals of Empodisma sampled from throughout the range of the species. The results support an Australian origin for Empodisma sometime during the late Oligocene to early Miocene with more recent dispersal, colonization and diversification in New Zealand. We recovered six genetically distinct maternal lineages: three Empodisma gracillimum haplotypes corresponding to the three accessions in our analysis, a wide-ranging Empodisma minus haplotype found in eastern Australia and Tasmania, an Empodisma minus haplotype found in New Zealand from Stewart Island to approximately 38° S latitude on the North Island, and a distinct haplotype restricted to the North Island of New Zealand north of 38° S latitude. The Eastern Australian and New Zealand haplotypes of Empodisma minus were supported by only one cpDNA gene, and we felt the relatively minor morphological differences and the small amount of genetic divergence did not warrant taxonomic recognition. However, we recommend that the northern New Zealand haplotype should be recognized as the new species Empodisma robustum and provide descriptions and a key to the species of Empodisma. Monophyly of Empodisma robustum is supported by all three cpDNA genes. Empodisma robustum can be distinguished from Empodisma gracillimum and Empodisma minus by its robust growth stature and distinct ecology. It is typically eliminated by fire and re-establishes by seed (seeder strategy), whereas Empodisma minus and Empodisma gracillimum regrow after fire (sprouter strategy). PMID:22787426

  9. Zero methane-emitting peatlands: biogeochemical features and forecasting response to environmental change

    NASA Astrophysics Data System (ADS)

    Sirin, Andrey; Suvorov, Gennady; Glagolev, Mikhail; Kravchenko, Irina; Chistotin, Maxim; Bazhin, Nikolai

    2014-05-01

    Peatlands are one of the main sources of atmospheric CH4, a greenhouse gas responsible for a large part of current climate forcing. Existing estimates of methane flux from peatlands on a country, continental and global scale do not cover all variety of extremely diverse natural peatland ecosystems, their spatial uncertainties, and related to human impacts modifications. During last 2-3 decades numerous CH4flux measurements were conducted in northern peatlands, but many peatland types were not elaborated being suggested as unessential or even 'zero' source of methane to the atmosphere. Among them are widespread forested dwarf-shrub sphagnum peatbogs, frozen flat palsa mires, etc., as well as considered 'dry' peatlands drained and utilized for peat extraction, agriculture and forestry. Methane fluxes were measured at key peatland taiga test-plots of Central part of European Russia and taiga and tundra-forest zones of West Siberia purposely to examine periods of different level of humidity. The water level (WL) position switching from methane emission to uptake was elucidated for pine-dwarf-shrub-sphagnum ecotopes: at 50 cm WL near-zero or negative methane fluxes were registered at 86% of measurements, at 40 cm WL - emission at 89%. Observations in Central European Russia cover different natural and drained peatland types. Drainage and management usually decreased CH4 emissions relative to pristine peatlands through drying of surface peats and simultaneous decrease the size of anoxic horizons, but the rise of WL switches to CH4 fluxes. Relation between methane flux and peat wetness was additionally tested by series of lab mesocosm experiments. Processes resulting in similar final zero methane emissions under conditions of drained and intact peatland could be different. Microbial communities, involved in methane cycle, have been significantly changed in drained peatlands. Methanogens in natural peatlands were almost exclusively composed of hydrogenotrophs, whereas both

  10. Will climate change exceed the resilience limits of western Canadian peatlands?

    NASA Astrophysics Data System (ADS)

    Turetsky, M. R.; Benscoter, B.; Olefeldt, D.

    2014-12-01

    Northern peatlands have served as persistent, small sinks of atmospheric CO2 throughout the Holocene. In western Canada, peatlands exist on the drier spectrum of global peatland distributions. As a result, peatlands in this region are drier (e.g., no/few open pools in bogs and poor fens) and all bogs are treed. Because they occupy this climate space, continental peatlands might be regarded as being vulnerable to future warming and drying. On the other hand, these peatlands and their plant communities might already be adapted to drier conditions, conferring some resistance to climate change. The position of the water table within a peatland serves as a dominant control on peat accumulation rates, as it influences plant structure and productivity, decomposition, and dissolved carbon export. Many studies predict that lower water table position, in response to enhanced evapotranspiration or drought, will cause peatlands to release stored C back to the atmosphere, indicative of a state change to an ecosystem type that no longer supports long-term peat accumulation. A 10-yr drainage experiment at the Alaska Peatland Experiment (APEX) sites showed that lowering the water table made a rich fen more of an atmospheric C source, primarily by altering plant species composition and lowering plant primary production rather than by increasing soil CO2 flux. Multi-decadal drainage of Canadian peatlands also resulted in changes in plant species composition, with increasing tree and shrub canopy coverage and declines in moss abundance. Increased forestation in western Canadian peatlands will have large impacts on fire danger, which also has the potential to cause long-term shifts in plant and ecosystem structure, either through severe burning of surface peat layers or by inducing permafrost thaw. This talk will present findings from empirical and modeling studies examining peatland responses to warming, drought, permafrost thaw, and wildfires. Within the context of these dominant

  11. Properties of peatlands in relation to environmental factors in Minnesota

    SciTech Connect

    Swanson, D.K.

    1988-01-01

    The relationship of peatland morphology and distribution to environmental factors was investigated in northern and central Minnesota by field sampling of vegetation, soils, and water, and by remote sensing. Maps of peatlands made by machine classification of Landsat data six classes matched field data in 56% of all cases; maps drawn by hand on 1:80,000 scale aerial photographs were 72% correct. Peatland sites fall into two natural groups: ombrotrophic (bogs; pH less than 4.4) and minerotrophic (fens and swamps: pH 4.4 or more and usually greater than 5.6). The presence of certain common vascular-plant taxa can be used to classify sites into these trophic classes with over 90% accuracy. The structure of peatland vegetation is controlled by the soil-water regime, the disturbance history, and, to a less degree, by trophic conditions. Sites that have relatively well-aerated soils and have not been recently disturbed support dense forests. Vegetation structure is weakly related to the degree of decomposition of peat; hence vegetation is a poor indicator for taxonomic units of organic soils. Peatlands are common in Minnesota on surfaces glaciated during the Wisconsin Stage and where the mean annual potential evapotranspiration roughly equals or exceeds the mean annual precipitation. Bogs occur most often on sites where a high water table can be maintained without groundwater discharge, such as in depressions on low-permeability substrates and near local watershed divides on plains. Fens apparently occur in or below areas of groundwater discharge. Swamps (densely forested minerotrophic peatlands) occur in a wide variety of settings where the soil is aerated during the growing season.

  12. Acceptance of the Theory of Evolution in America: Louis Agassiz vs. Asa Gray

    ERIC Educational Resources Information Center

    Wolfe, Elaine Claire Daughetee

    1975-01-01

    Provides some background information on the contributions of Louis Agassiz and Asa Gray to the history of American science as these two men disagreed concerning the ideas in Darwin's "The Orgin of Species." (PB)

  13. Decomposition and organic matter quality in continental peatlands: The ghost of permafrost past

    USGS Publications Warehouse

    Turetsky, M.R.

    2004-01-01

    Permafrost patterning in boreal peatlands contributes to landscape heterogeneity, as peat plateaus, palsas, and localized permafrost mounds are interspersed among unfrozen bogs and fens. The degradation of localized permafrost in peatlands alters local topography, hydrology, thermal regimes, and plant communities, and creates unique peatland features called "internal lawns." I used laboratory incubations to quantify carbon dioxide (CO 2) production in peat formed under different permafrost regimes (with permafrost, without permafrost, melted permafrost), and explored the relationships among proximate organic matter fractions, nutrient concentrations, and decomposition. Peat within each feature (internal lawn, bog, permafrost mound) is more chemically similar than peat collected within the same province (Alberta, Saskatchewan) or within depth intervals (surface, deep). Internal lawn peat produces more CO2 than the other peatland types. Across peatland features, acid-insoluble material (AIM) and AIM/nitrogen are significant predictors of decomposition. However, within each peatland feature, soluble proximate fractions are better predictors of CO2 production. Permafrost stability in peatlands influences plant and soil environments, which control litter inputs, organic matter quality, and decomposition rates. Spatial patterns of permafrost, as well as ecosystem processes within various permafrost features, should be considered when assessing the fate of soil carbon in northern ecosystems. ?? 2004 Springer Science+Business Media, Inc.

  14. Selenium and metal concentrations in waterbird eggs and chicks at Agassiz National Wildlife Refuge, Minnesota

    USGS Publications Warehouse

    Custer, T.W.; Custer, Christine M.; Eichhorst, B.A.; Warburton, D.

    2007-01-01

    Exceptionally high cadmium (Cd) and chromium (Cr) concentrations were reported in eggs, feathers, or livers of selected waterbird species nesting at Agassiz National Wildlife Refuge (Agassiz) in 1994. Ten- to 15-day-old Franklin's gull (Larus pipixcan), black-crowned night-heron (Nycticorax nycticorax), and eared grebe (Podiceps nigricollis) chicks were collected in 1998, 1999, and 2001 at Agassiz and analyzed for selenium (Se) and metals including Cd and Cr. Freshly laid eggs were collected in 2001 from Franklin's gull, black-crowned night-heron, eared grebe, and pied-billed grebe (Podilymbus podiceps) nests at Agassiz. Based on a multivariate analysis, the pattern of Se and metal concentrations differed among species for eggs, chick feathers, and chick livers. Low Cd and Cr concentrations were measured in eggs, chick livers, and chick feathers of all four species. Mercury concentrations in black-crowned night-heron and eared grebe eggs collected from Agassiz in 2001 were lower than concentrations reported in 1994. Se and metal concentrations, including Cd and Cr, in waterbird eggs and chicks collected at Agassiz in 1998, 1999, and 2001 were not at toxic levels. ?? 2007 Springer Science+Business Media, LLC.

  15. Selenium and metal concentrations in waterbird eggs and chicks at Agassiz National Wildlife Refuge, Minnesota.

    PubMed

    Custer, Thomas W; Custer, Christine M; Eichhorst, Bruce A; Warburton, David

    2007-07-01

    Exceptionally high cadmium (Cd) and chromium (Cr) concentrations were reported in eggs, feathers, or livers of selected waterbird species nesting at Agassiz National Wildlife Refuge (Agassiz) in 1994. Ten- to 15-day-old Franklin's gull (Larus pipixcan), black-crowned night-heron (Nycticorax nycticorax), and eared grebe (Podiceps nigricollis) chicks were collected in 1998, 1999, and 2001 at Agassiz and analyzed for selenium (Se) and metals including Cd and Cr. Freshly laid eggs were collected in 2001 from Franklin's gull, black-crowned night-heron, eared grebe, and pied-billed grebe (Podilymbus podiceps) nests at Agassiz. Based on a multivariate analysis, the pattern of Se and metal concentrations differed among species for eggs, chick feathers, and chick livers. Low Cd and Cr concentrations were measured in eggs, chick livers, and chick feathers of all four species. Mercury concentrations in black-crowned night-heron and eared grebe eggs collected from Agassiz in 2001 were lower than concentrations reported in 1994. Se and metal concentrations, including Cd and Cr, in waterbird eggs and chicks collected at Agassiz in 1998, 1999, and 2001 were not at toxic levels. PMID:17464443

  16. Modeling methane emissions from boreal peatlands

    NASA Astrophysics Data System (ADS)

    Raivonen, Maarit; Smolander, Sampo; Mäkelä, Jarmo; Tomasic, Marin; Aalto, Tuula; Markkanen, Tiina; Susiluoto, Jouni; Kleinen, Thomas; Brovkin, Victor; Rinne, Janne; Lohila, Annalea; Aurela, Mika; Vesala, Timo

    2014-05-01

    Natural wetlands are a significant source of methane (CH4): they have been estimated to account for about 30% of total global CH4 emissions. At the moment, the emission estimates are highly uncertain. These natural emissions respond to climatic variability, so it is necessary to understand their dynamics, in order to be able to predict how they affect the greenhouse-gas balance in the future. We have developed a model of CH4 production and transport in boreal peatlands. The aim is to make it a part of JSBACH, the land component of the Earth System Model of MPI Hamburg. The soil carbon model of JSBACH simulates peatland carbon processes like peat accumulation and decomposition and our CH4 module simulates production of CH4 as a proportion of the anaerobic peat decomposition, transport of CH4 and oxygen between the soil and the atmosphere, and oxidation of CH4 by methanotrophic microbes. The model has the three main pathways for transport: diffusion in aerenchymatous plants and in peat pores (water and air filled) and CH4 ebullition. The oxidation of CH4 depends on the oxygen concentrations in the peat. The model is largely based on existing models of CH4 production and transport but it includes some modifications that we will present here. We also will present the results of the first validations against observational data. The datasets are from two Finnish peatland sites, Siikaneva (southern) and Lompolojänkkä (northern Finland). Measurements of eddy covariance CH4 and CO2 fluxes and meteorological variables, as well as diverse ecological studies have been carried out on both sites over several years.

  17. Trade-Offs in Resource Allocation Among Moss Species Control Decomposition in Boreal Peatlands

    SciTech Connect

    Turetsky, M. R.; Crow, S. E.; Evans, R. J.; Vitt, D. H.; Wieder, R. K.

    2008-01-01

    We separated the effects of plant species controls on decomposition rates from environmental controls in northern peatlands using a full factorial, reciprocal transplant experiment of eight dominant bryophytes in four distinct peatland types in boreal Alberta, Canada. Standard fractionation techniques as well as compound-specific pyrolysis molecular beam mass spectrometry were used to identify a biochemical mechanism underlying any interspecific differences in decomposition rates. We found that over a 3-year field incubation, individual moss species and not micro-environmental conditions controlled early stages of decomposition. Across species, Sphagnum mosses exhibited a trade-off in resource partitioning into metabolic and structural carbohydrates, a pattern that served as a strong predictor of litter decomposition. Decomposition rates showed a negative co-variation between species and their microtopographic position, as species that live in hummocks decomposed slowly but hummock microhabitats themselves corresponded to rapid decomposition rates. By forming litter that degrades slowly, hummock mosses appear to promote the maintenance of macropore structure in surface peat hummocks that aid in water retention. Many northern regions are experiencing rapid climate warming that is expected to accelerate the decomposition of large soil carbon pools stored within peatlands. However, our results suggest that some common peatland moss species form tissue that resists decomposition across a range of peatland environments, suggesting that moss resource allocation could stabilize peatland carbon losses under a changing climate.

  18. Carbon pools and accumulation in peatlands of the former Soviet Union

    SciTech Connect

    Botch, M.S.; Kobak, K.I.; Vinson, T.S.

    1995-03-01

    To date, the areal extent, carbon pools, rate of carbon accumulation, and role of peatlands of the former Soviet Union (FSU) in the terrestrial carbon cycle has not been fully recognized. This is a consequence of the fact that may peatlands in the FSU, especially noncommercial peatlands, were never studied and properly mapped. An estimate of the areal extent, carbon pools, and rate of carbon accumulation in peatlands of the FSU obtained by interrelating a number of regional databases and maps, including formerly classified maps, is presented herein. Commercial peatlands were categorized by regional type which facilitated an evaluation of their age and quality. Noncommercial peatlands were evaluated from classified regional topographic maps. Air photographs were used to identify peatlands of northern landscapes. the total peatland area of the FSU was estimated at 165 Mha (10{sup 6} hectares) which was two times greater than the most recent estimates based on thematic maps. The peat carbon pool was estimated at 215 Pg C. Half of this amount was in raised bogs. The rate of peat accumulation varied from 12 g C m{sup -2} yr{sup -1} (polygonal mires) to 72-80 g C m{sup -2} yr{sup -1} (fens and marshes). The total rate of carbon accumulation in FSU peatlands was 52 Tg C yr{sup -1}. Carbon emissions from peat utilization in the FSU were estimated at 122 Tg C yr{sup -1}. Thus, at present, peat accumulation/utilization in the FSU is a net source of approximately 70 Tg C yr{sup -1} to the atmosphere. 45 refs, 1 fig., 3 tabs.

  19. Carbon Distribution and Net Primary Production in a Forest-Peatland Landscape Mosaic

    NASA Astrophysics Data System (ADS)

    Weishampel, P.; Kolka, R.; King, J.

    2007-12-01

    We characterized the distribution of carbon and annual NPP in a mixed forest and peatland landscape in the Marcell Experimental Forest in northern Minnesota, USA. We estimated vegetation biomass and production (aboveground and belowground) and the carbon content of detrital pools (forest floor, woody debris, and mineral soil or peat) in a 1-km2 area that encompassed multiple vegetation cover types, including forested uplands dominated by aspen, mixed-hardwood, or pine, and peatlands dominated by alder, conifers, or ericaceous shrubs and Sphagnum mosses (open peatlands). In aspen dominated areas, which account for >70% of our study area, total C storage was 164 ± 9 Mg C ha-1 while pine and hardwood dominated averaged 190 ± 16 and 153 ± 19 Mg C ha-1 respectively. Total ecosystem carbon content in peatland areas averaged 1380 ± 170 Mg C ha-1 and was highly dependent upon peat depth. Among upland cover types, NPP was greatest in pine-dominated areas (6.2 ± 0.6 Mg C ha-1) and similar in aspen- and hardwood- dominated areas (4.7 ± 0.2 and 4.5 ± 0.5 Mg C ha-1, respectively). We found considerable variability in NPP among peatland cover types; in coniferous peatlands, alder peatlands, and open peatlands, NPP was 6.0, 2.8 ± 0.4 and 1.4 ± 0.2 Mg C ha-1 respectively. Large differences in NPP among peatland cover types as well as smaller but significant differences between deciduous and coniferous upland cover types illustrate the importance of these cover types when scaling carbon cycling to landscape and regional levels.

  20. How hydrology and vegetation modify microclimate of a Sphagnum peatland?

    NASA Astrophysics Data System (ADS)

    Słowińska, Sandra; Słowiński, Michał; Marcisz, Katarzyna; Lamentowicz, Łukasz; Lamentowicz, Mariusz

    2014-05-01

    Climate and hydrology are key factors influencing peat accumulation and decomposition. This, in turn have strong influence on carbon sequestration what is nowadays the central aim of peatlands ecology. However, peatlands are not homogenous ecosystems. There are often a mosaic of vegetation patterns. Differences in depth of groundwater tables are also common at one object. We designed a long-term ecological study site in a Sphagnum peatland in the Northern Poland. We used five meteorological micro-stations and eleven piezometers located along two transects at 5,95 ha area. We have focused on microclimatic and hydrological changes during two growing seasons - 2012 and 2013. Significant differences in radiation, air temperature and humidity were recorded between plots, which were mainly a result of reduction of light availability by trees in two of five plots. That also influenced on surface wetness of Sphagnum mosses. Range of groundwater table changes varied between plots but trends were similar. Further research will focus on the synthesis of relationships between climate, hydrology and vegetation. A separate work will be concentrated on testate amoebae response to wetness, temperature and light availability. Our study is very important to better understand peatland functioning in transition climate in small spatial scale. Project supported by Polish National Science Centre grant No. NN306060940 and the grant PSPB-013/2010 from Switzerland through the Swiss Contribution to the enlarged European Union.

  1. Constraints on Lake Agassiz discharge through the late-glacial Champlain Sea (St. Lawrence Lowlands, Canada) using salinity proxies and an estuarine circulation model

    USGS Publications Warehouse

    Katz, B.; Najjar, R.G.; Cronin, T.; Rayburn, J.; Mann, M.E.

    2011-01-01

    During the last deglaciation, abrupt freshwater discharge events from proglacial lakes in North America, such as glacial Lake Agassiz, are believed to have drained into the North Atlantic Ocean, causing large shifts in climate by weakening the formation of North Atlantic Deep Water and decreasing ocean heat transport to high northern latitudes. These discharges were caused by changes in lake drainage outlets, but the duration, magnitude and routing of discharge events, factors which govern the climatic response to freshwater forcing, are poorly known. Abrupt discharges, called floods, are typically assumed to last months to a year, whereas more gradual discharges, called routing events, occur over centuries. Here we use estuarine modeling to evaluate freshwater discharge from Lake Agassiz and other North American proglacial lakes into the North Atlantic Ocean through the St. Lawrence estuary around 11.5 ka BP, the onset of the Preboreal oscillation (PBO). Faunal and isotopic proxy data from the Champlain Sea, a semi-isolated, marine-brackish water body that occupied the St. Lawrence and Champlain Valleys from 13 to 9 ka, indicate salinity fell about 7-8 (range of 4-11) around 11.5 ka. Model results suggest that minimum (1600 km3) and maximum (9500 km3) estimates of plausible flood volumes determined from Lake Agassiz paleoshorelines would produce the proxy-reconstructed salinity decrease if the floods lasted <1 day to 5 months and 1 month to 2 years, respectively. In addition, Champlain Sea salinity responds very quickly to the initiation (within days) and cessation (within weeks) of flooding events. These results support the hypothesis that a glacial lake flood, rather than a sustained routing event, discharged through the St. Lawrence Estuary during the PBO. ?? 2011 Elsevier Ltd.

  2. Altered peat hydrophysical properties following drainage and wildfire increases peatland vulnerability to ecosystem regime shift

    NASA Astrophysics Data System (ADS)

    Waddington, James; Kettridge, Nick; Sherwood, James; Granath, Gustaf

    2015-04-01

    Northern peatlands represent a globally significant carbon reservoir, composed largely of legacy carbon which is no longer part of the active carbon cycle. However, it is unclear whether this legacy carbon is vulnerable as a result of enhanced peat smouldering and combustion under the moderate drying conditions predicted for northern peatlands as a result of climate change and/or disturbance from forestry, mining, and associated transport development. A significant loss in legacy carbon as a result of wildfire has already been observed in smaller tropical peatlands where deep peat soils have been destabilized due to severe drainage and a shift in vegetation. Capitalizing on a unique long-term experiment, we quantify the post-wildfire recovery of a northern peatland several decades post drainage. We show that the moderate drop in water table position predicted for most northern regions triggers a shift in vegetation composition, previously observed within only severely disturbed tropical peatlands, when accompanied by wildfire. The combined impact of moderate drainage followed by wildfire resulted in a shift of the peat surface down the peat profile, exposing denser peat at the surface. In undisturbed northern peatlands where depth of burn is typically low, low-density near-surface peats help regulate water-table position and near-surface moisture availability post-fire, both of which are favourable to Sphagnum recolonization. As a result of drainage and fire at the study site, the self-regulating properties of the low-density Sphagnum surface were lost. We demonstrate that changes in peat hydrophysical properties increased hydrological limitations to Sphagnum recovery leading to the conversion to a non-carbon accumulating shrub-grass ecosystem. This new ecosystem is likely to experience a low intensity, high frequency wildfire regime, which will further deplete the legacy carbon stored in the peat.

  3. Macroinvertebrate community assembly in pools created during peatland restoration.

    PubMed

    Brown, Lee E; Ramchunder, Sorain J; Beadle, Jeannie M; Holden, Joseph

    2016-11-01

    Many degraded ecosystems are subject to restoration attempts, providing new opportunities to unravel the processes of ecological community assembly. Restoration of previously drained northern peatlands, primarily to promote peat and carbon accumulation, has created hundreds of thousands of new open water pools. We assessed the potential benefits of this wetland restoration for aquatic biodiversity, and how communities reassemble, by comparing pool ecosystems in regions of the UK Pennines on intact (never drained) versus restored (blocked drainage-ditches) peatland. We also evaluated the conceptual idea that comparing reference ecosystems in terms of their compositional similarity to null assemblages (and thus the relative importance of stochastic versus deterministic assembly) can guide evaluations of restoration success better than analyses of community composition or diversity. Community composition data highlighted some differences in the macroinvertebrate composition of restored pools compared to undisturbed peatland pools, which could be used to suggest that alternative end-points to restoration were influenced by stochastic processes. However, widely used diversity metrics indicated no differences between undisturbed and restored pools. Novel evaluations of restoration using null models confirmed the similarity of deterministic assembly processes from the national species pool across all pools. Stochastic elements were important drivers of between-pool differences at the regional-scale but the scale of these effects was also similar across most of the pools studied. The amalgamation of assembly theory into ecosystem restoration monitoring allows us to conclude with more certainty that restoration has been successful from an ecological perspective in these systems. Evaluation of these UK findings compared to those from peatlands across Europe and North America further suggests that restoring peatland pools delivers significant benefits for aquatic fauna by

  4. Do Peatlands Hibernate?

    NASA Astrophysics Data System (ADS)

    Dorrepaal, E.; Signarbieux, C.; Jassey, V.; Mills, R.; Buttler, A.; Robroek, B.

    2014-12-01

    . Altogether, our data indicate that peatlands are active in winter. However, a continuous snow cover is crucial for ecosystem processes both in winter and in the subsequent summer and a reduction of snow thickness or duration due to climate change may impact on peatland ecosystem functioning at various levels.

  5. Can boreal peatlands with pools be net sinks for CO2?

    NASA Astrophysics Data System (ADS)

    Pelletier, Luc; Strachan, Ian B.; Roulet, Nigel T.; Garneau, Michelle

    2015-03-01

    Peatland open-water pools, a common feature on temperate to subarctic peatlands, are sources of carbon (C) to the atmosphere but their contribution to the net ecosystem carbon dioxide exchange (NEE-CO2) is poorly known; there is a question as to whether peatlands with pools are smaller sinks of atmospheric C, or even C-neutral, compared to other peatlands. We present growing season NEE-CO2 measurements using the eddy covariance technique in a peatland with pools. We found the maximum photosynthetic uptake and ecosystem respiration rates at 10 °C to be in the lower range of the published data. The lower total vegetation biomass, due to the presence of pools, reduced CO2 uptake during day and the autotrophic component of ecosystem respiration. The low CO2 uptake combined with reduced CO2 loss resulted in the site being a net sink for CO2 of a similar magnitude as other northern peatlands despite the inclusion of pools.

  6. A subtropical fate awaited freshwater discharged from glacial Lake Agassiz

    SciTech Connect

    Condron, Alan; Winsor, Peter

    2011-02-10

    The 8.2 kyr event is the largest abrupt climatic change recorded in the last 10,000 years, and is widely hypothesized to have been triggered by the release of thousands of kilometers cubed of freshwater into the North Atlantic Ocean. Using a high-resolution (1/6°) global, ocean-ice circulation model we present an alternative view that freshwater discharged from glacial Lake Agassiz would have remained on the continental shelf as a narrow, buoyant, coastal current, and would have been transported south into the subtropical North Atlantic. The pathway we describe is in contrast to the conceptual idea that freshwater from this lake outburst spread over most of the sub-polar North Atlantic, and covered the deep, open-ocean, convection regions. This coastally confined freshwater pathway is consistent with the present-day routing of freshwater from Hudson Bay, as well as paleoceanographic evidence of this event. In this study, using a coarse-resolution (2.6°) version of the same model, we demonstrate that the previously reported spreading of freshwater across the sub-polar North Atlantic results from the inability of numerical models of this resolution to accurately resolve narrow coastal flows, producing instead a diffuse circulation that advects freshwater away from the boundaries. To understand the climatic impact of freshwater released in the past or future (e.g. Greenland and Antarctica), the ocean needs to be modeled at a resolution sufficient to resolve the dynamics of narrow, coastal buoyant flows.

  7. Geophysical Evidence for Abiotic Controls on Peatland Patterning at Multiple Scales

    NASA Astrophysics Data System (ADS)

    Nolan, J.; Slater, L.; Glaser, P.; Comas, X.; O'Brien, M.

    2007-12-01

    The autogenic and allogenic controls on the formation of distinctive and dramatic vegetation patterning found in northern peatlands remain unclear. Groundwater model studies and investigations using point measurements lack intensive data over multiple scales, primarily due to the intensive time required and difficult logistics required to work in these remote ecosystems. We provide geophysical evidence that lithological controls on vegetation patterning exist at multiple scales in ombrotrophic peatlands of northern Minnesota and Maine. Surveys using electrical imaging methods (including resistivity, induced polarization, and ground penetrating radar) at sites in the Red Lake Peatland Complex (160 km2), as well as Kanokolus Bog (1.65 km2) and the Caribou Bog Peatland Complex (22 km2) in Maine reveal sharp vegetation gradients coinciding with changes in the mineral soil lithology. In contrast, large-scale, continuous, patterned zones found in the Red lake Complex coincide with strikingly uniform mineral soil lithology as inferred from the geophysical images. Small-scale (0.3 km2) vegetation patterns observed in Caribou Bog also coincide with small scale lithologic changes in both the mineral and organic deposits. These results provide evidence that the subsurface hydrogeologic framework regulates vegetation patterning in peatlands across multiple scales, presumably by regulating (1) the supply of mineral solutes to the surface vegetation water, and (2) water levels within the organic soil.

  8. Extraction, drainage, rewetting, flooding - Patterns of greenhouse gas turnover in restoring temperate peatlands

    NASA Astrophysics Data System (ADS)

    Glatzel, Stephan

    2016-04-01

    The disturbance of natural peatlands destroys carbon sink and is often associated with nitrous oxide emissions. Therefore, the general efforts to mitigate greenhouse gas sources and to create carbon sinks also include peatland restoration. The variety of peatland type (most importantly bog or fen), use (extraction or agriculture), and restoration technique (rewetting or flooding) result in specific patterns of greenhouse gas uptake or emission. Based on examples from own work, I present an overview of the greenhouse gas turnover of following sites: • Cutover peat bogs in Eastern Canada and following rewetting, flooding, and abandonment • Drained cutover and agriculturally used peat bogs in Northern Germany and following extensive agricultural management, paludiculture, rewetting, flooding, and abandonment • Drained agriculturally used fens in Northern Germany and following flooding and paludiculture I show that rewetting, but not flooding may succeed in re-establishing long-term carbon sinks with low methane release rates comparable to the greenhouse gas turnover known from natural peatlands. Flooding risks creating, at least in the short term, extremely strong methane sources. Extensive agricultural management and paludiculture may result in low methane, carbon dioxide and nitrous oxide release rates and could be a sensible option when aiming at reconciling peatland use and protection.

  9. Impacts of peatland restoration on dissolved carbon loss from eroded upland peatlands in the UK

    NASA Astrophysics Data System (ADS)

    Evans, M.; Stimson, A.; Allott, T. E. H. A.; Holland, N.

    2012-04-01

    Upland blanket peatlands in the UK are severely degraded by extensive gully erosion. Large areas have experienced complete vegetation loss. In the last decade landscape scale approaches to the restoration of eroded and bare peat have been developed in the Peak District National Park in northern England. Bare peat is re-vegetated with a nurse crop of grasses established by the aerial application of lime, seed, and fertiliser. The approach has successfully re-vegetated large areas of eroded bog a nd has been shown to dramatically reduce particulate carbon losses in runoff. The impacts of the treatment on water quality and dissolved carbon loss have not previously been fully assessed. This paper reports results from a small catchment study assessing the impacts of restoration practice in the Peak District. Data from five small catchments are presented one re-vegetated, one intact and three eroded/bare catchments. Bi-weekly water samples have been taken from the catchments between January 2011 and February 2012 and during July 2012 two of the bare sites were treated with lime, seed, and fertiliser. The data show that there are significant spikes in nutrient flux post treatment and marked effects on dissolved carbon which include initial spikes in in DOC concentration but longer term reductions in DOC concentration. Monitoring is ongoing at these sites but the evidence to date points to at least a short term benefit in DOC flux reduction from this form of peatland restoration.

  10. Upscaling microtopography in high-latitude peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, F.; Runkle, B. R.; Kleinen, T.; Kutzbach, L.; Boike, J.; Brovkin, V.

    2013-12-01

    A challenging problem in climate modeling is how to deal with interactions and feedbacks across a multiplicity of spatial scales, and how to improve our understanding of the role played by local soil heterogeneities in the climate system. This is of particular interest in northern peatlands, because of the large amount of carbon stored in the soil. Greenhouse gas (GHG) fluxes, such as methane, carbon dioxide and water vapor, vary largely within the environment, as an effect of the small scale processes that characterize the landscape. It is then essential to consider the local heterogeneous behavior of the system components in order to properly estimate water and carbon balances. We propose a novel method to fill the scaling gap from local mechanistic models to large scale mean field approximations. We developed a surface model for peatlands working at the landscape scale, which is able to show the impact of surface microtopography in modeling greenhouse gas fluxes. We tuned our landscape-scale model with data from a peatland site in the Komi Republic of Russia. We simulate surface microtopography and hydrology, and we couple it to a process-based model for methane emissions from the soil (Walter and Heiman, 1996). By partitioning the space in smaller subunits and then analyzing the statistical properties of the tiling, we are able to resolve the small scale processes and investigate their effects at larger scales. We not only investigate the influence of the hummocky surface on GHG emissions, but we are also able to simulate how complex hydrological interactions happening within the system at a subgrid scale affect the landscape-scale land-atmosphere GHG fluxes. We force our model climatology with data from the CMIP5 experiments. Future projections use forcing from the RCP 8.5 scenario, in order to investigate the impact of microrelieves on the future carbon cycle. We also explore potential dynamical feedbacks with the atmospheric water cycle and energy balance by

  11. Regional variation of natural peatland pool biogeochemistry and carbon concentrations

    NASA Astrophysics Data System (ADS)

    Turner, Ed; Billett, Mike; Chapman, Pippa; Baird, Andy; Dinsmore, Kerry; Holden, Joseph

    2015-04-01

    Natural open-water pools are a common feature of northern peatlands. They are characterised by low primary production, low pH, and often high concentrations of dissolved organic carbon (DOC). Peatland pools are also sources of atmospheric CH4, and thus have the potential to play an important role in global radiative forcing. Pool environmental variables, particularly water chemistry, vegetation community and physical characteristics, have the potential to exert strong controls on C cycling in pools; however, to our knowledge, no existing studies have addressed the potential variation in pool biogeochemistry and physical characteristics on a regional basis. A total of 66 peatland pools were studied across three regions of the UK (northern Scotland, south-west Scotland, and Northern Ireland) over the period September - October 2013. Vegetation communities, mean depth and basic water chemistry (pH, electrical conductivity and dissolved oxygen) were measured in situ. Water samples were taken for analysis of DOC, POC, DIC, CH4diss, CO2diss(dissolved CO2 and CH4),total N and P, and Cl-, SO42- and NO3-. To evaluate the composition of DOC, UV absorption was measured at 665, 470, 465, 436, 400, 360, 265, 254 nm. We show that many pool variables are significantly different between regions, including DOC, POC and CH4diss. The higher ratio of absorbance at 465 to absorbance at 665nm (E4/E6) for pools in Northern Ireland indicates DOC was sourced from less humified peat, which has implications for the bioavailability and mineralisation of organic carbon. Anion concentrations were significantly higher in the pools in northern Scotland than elsewhere, most likely due to a marine influence. SO42- is a CH4 electron acceptor and thus concentrations may influence methanogenesis. Hierarchical cluster analysis shows clear grouping of the individual pools within each region. PCA analysis showed that pools in SW Scotland were strongly associated with greater vegetative cover (Sphagnum

  12. Methanotrophs Contribute to Peatland Nitrogen

    NASA Astrophysics Data System (ADS)

    Larmola, Tuula; Leppänen, Sanna M.; Tuittila, Eeva-Stiina; Aarva, Maija; Merilä, Päivi; Fritze, Hannu; Tiirola, Marja

    2016-04-01

    Atmospheric nitrogen (N2) fixation is potentially an important N input mechanism to peatland ecosystems, but the extent of this process may have been underestimated because of the methods traditionally used inhibit the activity of methanothrophs. We examined the linkage of methane (CH4) oxidation and N2 fixation using 15N2 technique. Dominant flark and hummock Sphagnum species were collected from twelve pristine peatlands in Siikajoki, Finland, which varied in age from 200 to 2,500 y due to the postglacial rebound. The mosses were incubated in a two-day field 15N2 and 13CH4 pulse labelling experiment and the incorporation of 15N2 and 13CH4 in biomass was measured with Isotope Ratio Mass Spectrometer. The rates of Sphagnum-associated N2 fixation (0.1-2.9 g N m-2 y-1) were up to 10 times the current N deposition rates. Methane-induced N2 fixation contributed to over 1/3 of moss-associated N2 fixation in younger stages, but was switched off in old successional stages, despite active CH4 oxidation in these stages. Both the N2 fixation rates and the methanotrophic contribution to N2 fixation during peatland succession were primarily constrained by phosphorus availability. Previously overlooked methanotrophic N contribution may explain rapid peat and N accumulation during fen stages of peatland development. Reference. Larmola T., Leppänen S.M., Tuittila E.-S, Aarva M., Merilä P., Fritze H., Tiirola M. (2014) Methanotrophy induces nitrogen fixation during peatland development. Proceedings of the National Academy of Sciences USA 111 (2): 734-739.

  13. A subtropical fate awaited freshwater discharged from glacial Lake Agassiz

    DOE PAGESBeta

    Condron, Alan; Winsor, Peter

    2011-02-10

    The 8.2 kyr event is the largest abrupt climatic change recorded in the last 10,000 years, and is widely hypothesized to have been triggered by the release of thousands of kilometers cubed of freshwater into the North Atlantic Ocean. Using a high-resolution (1/6°) global, ocean-ice circulation model we present an alternative view that freshwater discharged from glacial Lake Agassiz would have remained on the continental shelf as a narrow, buoyant, coastal current, and would have been transported south into the subtropical North Atlantic. The pathway we describe is in contrast to the conceptual idea that freshwater from this lake outburstmore » spread over most of the sub-polar North Atlantic, and covered the deep, open-ocean, convection regions. This coastally confined freshwater pathway is consistent with the present-day routing of freshwater from Hudson Bay, as well as paleoceanographic evidence of this event. In this study, using a coarse-resolution (2.6°) version of the same model, we demonstrate that the previously reported spreading of freshwater across the sub-polar North Atlantic results from the inability of numerical models of this resolution to accurately resolve narrow coastal flows, producing instead a diffuse circulation that advects freshwater away from the boundaries. To understand the climatic impact of freshwater released in the past or future (e.g. Greenland and Antarctica), the ocean needs to be modeled at a resolution sufficient to resolve the dynamics of narrow, coastal buoyant flows.« less

  14. A Study of Library Service in the Lake Agassiz Region of North Dakota.

    ERIC Educational Resources Information Center

    North Dakota State Library Commission, Bismarck.

    A needs assessment of the library services of the Lake Agassiz region of North Dakota was begun in 1974. A mail survey of the area population and an in-library user survey were conducted. Almost all libraries in the region fell below state standards on holdings primarily because the population base was inadequate to support 11 municipal libraries.…

  15. Morton, Agassiz, and the Origins of Scientific Racism in the United States.

    ERIC Educational Resources Information Center

    Menand, Louis

    2002-01-01

    Describes how the racist academic consensus was established at Harvard University, focusing on two professors, Samuel George Morton and Louis Agassiz, who worked to convince U.S. scholars of the inherent inferiority and subhuman status of the black race. Morton published data on the inferiority of the black race based on analysis of his collection…

  16. Museum of Comparative Zoology Library--The Agassiz Library: Harvard University.

    ERIC Educational Resources Information Center

    Jonas, Eva S.; Regen, Shari S.

    1986-01-01

    Argues that the Museum of Comparative Zoology Library reflects the union between the nineteenth century natural history values of Louis Agassiz and the twentieth century library and information science methodology. Special collections, records, cataloging and classification, serials and their classification, policies, services, and procedures are…

  17. Frank Parsons's Enablers: Pauline Agassiz Shaw, Meyer Bloomfield, and Ralph Albertson

    ERIC Educational Resources Information Center

    Hershenson, David B.

    2006-01-01

    Frank Parsons was not the 1st American to recognize or address the need for vocational guidance. Why he, rather than his predecessors, is credited with initiating the field can be attributed to the largely overlooked contributions of 3 other persons: Pauline Agassiz Shaw, Meyer Bloomfield, and Ralph Albertson. The author calls attention to the…

  18. Water budget of a Quebec North-boreal minerotrophic peatland

    NASA Astrophysics Data System (ADS)

    Jutras, S.; Rousseau, A. N.; St-Hilaire, A.; Carrer, G.; Proulx-McInnis, S.; Clerc, C.; Levrel, G.

    2009-05-01

    A significant percentage of the northern Quebec boreal region consists of minerotrophic peatland. Their impact on large-scale watersheds, used for hydroelectric production, is important, especially in relation to climate change. During the last decades, a subtle increase in the surface of ponds at the expense of terrestrial compartments has been observed. To better understand the impacts of this development, a multidisciplinary study to perform a complete integrated analysis of the water balance was launched in summer 2008 on the Abeille peatland (54° 06'52" N, 72° 30'01"W), a minerotrophic peatland with an open-water surface. While all features of the water balance will be considered (precipitation, evapotranspiration, runoff, storage and error), some will be studied in greater depth. Notably, evapotranspiration and storage changes will be considered, since, they are particularly difficult to measure in peatland ecosystems. Indirect methods for estimating actual evapotranspiration are often used. One method is to use a semi-empirical formula to estimate potential evapotranspiration. The main problem with this method is that a relationship between potential and actual evapotranspiration must be established and this is a highly variable process for peat ecosystems. To establish a relationship appropriate to our study site, different methods of direct measurement of the actual evapotranspiration will be used (lysimeters, turbulence flow, daily fluctuations of storage, etc.) and compared. A dense network of wells has been installed to enable monitoring of changes in storage and subsurface runoff. A high accuracy topographic survey will be executed to assess the total water content of the site. A device for measuring the variation of peat surface elevation will also be established. Preliminary results are showing complex dynamic behaviors of water migration through the site, therefore opening the way to new questions and hypotheses to clarify in the coming years.

  19. The role of lichen on peatland development in the Hudson Bay Lowlands, Canada

    NASA Astrophysics Data System (ADS)

    Harris, Lorna; Moore, Tim; Roulet, Nigel

    2015-04-01

    Lichen (Cladina stellaris) can be a dominant vegetation cover on bogs within the extensive peatland landscape of the Hudson Bay Lowlands (HBL), northern Ontario, Canada. The unique characteristics of lichens (growth structure and function as a symbiotic organism), their ability to form thick, dense mats across the HBL bogs, and their increased tolerance of extreme environmental conditions, points to their importance as a distinct plant functional type. However, the role of lichen within the peatland ecosystem is poorly understood, particularly ecosystem interactions (vegetation associations) and peatland development (including microtopography) and the resulting carbon sink. Many studies consider the role of different plant functional types on peatland CO2 and CH4 exchange (e.g. Bubier et al., 2003; Strack et al., 2006), and this understanding is included in peatland growth and climate change models. As far as we are aware lichens are currently omitted from these models. We suggest that lichens represent a distinct plant functional type with CO2 exchange characteristics (NEE and respiration) that are quite different to vascular plants and mosses. In this study we measured lichen CO2 exchange in both natural and modified moisture conditions at field sites in the HBL over two field seasons. Our results indicate that lichen productivity is strongly influenced by abiotic factors that affect lichen moisture content, with very dry lichen exhibiting little or no photosynthetic capacity. We suggest that the low productivity of lichen mats results in lower rates of peat accumulation compared to Sphagnum-dominated peatland areas, and that this has consequences for the development of peatland microtopography (hummocks and hollows) and feedback mechanisms. To better understand the role of lichen mats on peat accumulation and to test possible feedback mechanisms we developed a model, the parameters of which are supported by data from field sites in the HBL. This dependence of

  20. Do volcanic emissions affect carbon gas fluxes in peatlands?

    NASA Astrophysics Data System (ADS)

    Harrison, Nicola; Delmelle, Pierre; Toet, Sylvia; Gauci, Vincent; Ineson, Phil

    2010-05-01

    Recently, a link has been suggested between volcanic deposition of SO4 and the suppression of CH4 emissions in northern peatlands (Gauci et al., 2008). This link stems from the widely accepted idea that acid rain SO4 additions to peatlands can cause a shift in microbial communities as SO4 reducing bacteria out-compete methanogens for substrates, which results in a suppression of CH4 emission. However, volcanic emissions contain besides S other chemically reactive species that are potentially harmful to the environment. In particular, gaseous and particulate F emissions from volcanoes constitute a steady or intermittent source of F emission and deposition into the environment both close to the source and within fallout range of large eruptions. The objective of this study was to investigate the effect of volcanic depositions of SO4, both alone and in combination with F, on CH4 emission in peatlands. Peat mesocosms collected from Pennine uplands in the UK were treated with weekly pulses of Na2SO4 and NaF over 20 weeks in doses of 74 kg SO4/ ha and 13.5 and 135 kg F /ha. CH4 emissions were measured at regular intervals by taking headspace samples, which were analysed by GC-FID. CO2 fluxes were also measured using a portable Infra Red Gas Analyser (IRGA). No significant differences in CH4 and CO2 emissions were observed for any of the treatments when compared to the controls, which had only received deionised water. These findings are in contrast with previous studies where SO4 reduces CH4 emission in peatlands. The reason for this is unclear but may be due to the heterogeneous nature of peat soils. An alternative explanation relates to the previous history of the soils used in the mesocosms which are known to have been previously exposed to large volumes of anthropogenic S pollution. This may have caused microbial communities to evolve and become acclimatised to high levels of S addition. In either case, the assumption that CH4 suppression in peatlands occurs upon

  1. Holocene climate change and peatland dynamics in the Altai Mountains in Northwest China

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Yu, Z.; Li, Q.; Zhao, W.

    2013-12-01

    Here we present preliminary results from a peat-core record to investigate responses of upland vegetation and peatlands to Holocene climate change in the Altai Mountains. Chronology of a 650-cm-long peat core from the Iron Arshad Khan (IAK) peatland in the western Altai Mountains was controlled by 20 AMS dates on identifiable terrestrial macrofossils, covering the entire Holocene. Lithology results indicate that the peat accumulation initiated at 11 ka (1 ka =1000 cal BP), with a sharp increase in organic matter content to >80%. Plant macrofossil data show a sequence of changes from the peatlands dominated by Cyperaceae before 8.1 ka, to Cyperaceae and brown moss-dominated at 8-4.5 ka, Sphagnum and Cyperaceae-dominated at 4.5-2 ka, and to Cyperaceae-dominated again after 2 ka. Carbon accumulation rates were highest at >40 gC/m2/yr at 8.5-7 ka, more than doubled the Holocene average at the site. Pollen analysis shows the highest tree pollen (mainly from Picea) of up to 59% occurred at 8-6.4 ka, suggesting a warm and wet mid-Holocene 'optimum' climate in the region. Organic matter bulk density shows an increasing trend after 6.4 ka, suggesting increasing cumulative decomposition of accumulated peat. Our multi-proxy data indicate clear responses of peatland species composition, moisture conditions and carbon accumulation to regional climate change. The cooling and drying trend since the mid-Holocene was likely in response to the decrease in summer insolation and in westerly-induced precipitation. Furthermore, our results from this temperate highland peatland may shed new lights on understanding peatland carbon dynamics in northern Eurasia, including the largest peatland basin in West Siberia, as well as Holocene climate changes in central Asia.

  2. Blanket peatland restoration leads to reduced storm runoff from headwater systems

    NASA Astrophysics Data System (ADS)

    Shuttleworth, Emma; Allott, Tim; Evans, Martin; Pilkington, Mike

    2016-04-01

    This paper presents data on the impact of largescale peatland restoration on catchment runoff from peatlands in northern England. The blanket peatlands of the Pennine hills are important sources of water supply and form the headwaters of major river systems. These peatlands are severely eroded with extensive gullying and bare peat resulting from the impacts of industrial pollution, overgrazing, wildfire and climatic change over the last millennium. In the last decade there has been a major programme of peatland restoration through re-vegetation and blocking of drainage lines in these systems. The Making Space for Water project has collected hydrological data from five micro-catchments(two restoration treatments, a bare peat control, a vegetated control and a previously restored site) over a four year period. This has allowed for both Before-After-Control-Intervention and Space for Time analysis of the impact of restoration on downstream runoff. Catchments became wetter following re-vegetation, water tables rose by 35 mm and overland flow production increased by 18%. Storm-flow lag times in restored catchments increased by up to 267 %, while peak storm discharge decreased by up to 37%. There were no statistically significant changes in percentage runoff, indicating limited changes to within-storm catchment storage. Natural flood management solutions are typically focussed around one of two main mechanisms, either enhanced storage of water in catchments or measures which slow transmission of water to channels and within channels. Upland peatlands are often mischaracterised as sponges and assumed to mitigate downstream runoff through additional storage. The results of this study suggest that whilst restoration of upland peatlands can lead to significant reductions in peak discharge, and has potential to contribute to natural flood risk management, the mechanism is an increase in catchment roughness and an associated decrease in flow velocities.

  3. The Burning of Surface and Deep Peat during Boreal Forest and Peatland Fires: Implications for Fire Behaviour and Global Carbon Cycling

    NASA Astrophysics Data System (ADS)

    Turetsky, M. R.

    2015-12-01

    Fire is increasingly appreciated as a threat to peatlands and their carbon stocks. The global peatland carbon pool exceeds that of global vegetation and is similar to the current atmospheric carbon pool. Under pristine conditions, most of the peat carbon stock is protected from burning, and resistance to fire has increased peat carbon storage in high latitude regions over long time scales. This, in part, is due to the high porosity and storage coefficient of surface peat, which minimizes water table variability and maintains wet conditions even during drought. However, higher levels of disturbance associated with warming and increasing human activities are triggering state changes and the loss of resiliency in some peatland systems. This presentation will summarize information on burn area and severity in peatlands under undisturbed scenarios of hydrologic self-regulation, and will assess the consequences of warming and drying on peatland vegetation and wildfire behaviour. Our goal is to predict where and when peatlands will become more vulnerable to deep smouldering, given the importance of deep peat layers to global carbon cycling, permafrost stability, and a variety of other ecosystem services in northern regions. Results from two major wildfire seasons (2004 in Alaska and 2014 in the Northwest Territories) show that biomass burning in peatlands releases similar amounts of carbon to the atmosphere as patterns of burning in upland forests, but that peatlands are less vulnerable to severe burning that tends to occur in boreal forests during late season fire activity.

  4. Moss and peat hydraulic properties are optimized to maximise peatland water use efficiency

    NASA Astrophysics Data System (ADS)

    Kettridge, Nicholas; Tilak, Amey; Devito, Kevin; Petrone, Rich; Mendoza, Carl; Waddington, Mike

    2016-04-01

    Peatland ecosystems are globally important carbon and terrestrial surface water stores that have formed over millennia. These ecosystems have likely optimised their ecohydrological function over the long-term development of their soil hydraulic properties. Through a theoretical ecosystem approach, applying hydrological modelling integrated with known ecological thresholds and concepts, the optimisation of peat hydraulic properties is examined to determine which of the following conditions peatland ecosystems target during this development: i) maximise carbon accumulation, ii) maximise water storage, or iii) balance carbon profit across hydrological disturbances. Saturated hydraulic conductivity (Ks) and empirical van Genuchten water retention parameter α are shown to provide a first order control on simulated water tensions. Across parameter space, peat profiles with hypothetical combinations of Ks and α show a strong binary tendency towards targeting either water or carbon storage. Actual hydraulic properties from five northern peatlands fall at the interface between these goals, balancing the competing demands of carbon accumulation and water storage. We argue that peat hydraulic properties are thus optimized to maximise water use efficiency and that this optimisation occurs over a centennial to millennial timescale as the peatland develops. This provides a new conceptual framework to characterise peat hydraulic properties across climate zones and between a range of different disturbances, and which can be used to provide benchmarks for peatland design and reclamation.

  5. Simulating the long-term response of peatlands to extraction and post-extraction management strategies

    NASA Astrophysics Data System (ADS)

    Quillet, Anne; Roulet, Nigel; Wu, Jianghua

    2016-04-01

    Peatlands have been and remain exploited either for agricultural purposes, forestry, peat extraction or infrastructure development in the northern latitudes as well as in the tropics. Modelling current and future carbon exchanges in peatlands thus requires further understanding of carbon dynamics in drained, exploited and restored peatlands. This study aimed at quantifying the centennial to millennial carbon balance in extracted and restored peatlands. On-site data measurements only started recently and only cover up to 15 years. The chosen approach was thus based on modelling. We modified the Holocene Peat Model (Frolking et al. 2010) to simulate peat extraction and restoration and calculate the carbon balance at different stages of exploitation and restoration. The model simulates drainage occurring prior to and during peat extraction, changes in peat bulk density and the specific vegetation succession occurring during the restoration process. As in the previous version of HPM, vegetation dynamics and interactions between vegetation and ecohydrology were included in the simulations. Simulation results offered an estimate of the amount of carbon accumulated in the peatland prior to exploitation as well as the carbon loss during exploitation. Estimates of current and future net carbon accumulation/loss, associated with different management scenarios, such as state-of-the-art restoration, drainage blocking or abandonment, gave an insight into the benefits of restoration and moreover into the millennial scale impact of peat extraction.

  6. Drivers of Holocene peatland carbon accumulation across a climate gradient in northeastern North America

    NASA Astrophysics Data System (ADS)

    Charman, Dan J.; Amesbury, Matthew J.; Hinchliffe, William; Hughes, Paul D. M.; Mallon, Gunnar; Blake, William H.; Daley, Tim J.; Gallego-Sala, Angela V.; Mauquoy, Dmitri

    2015-08-01

    Peatlands are an important component of the Holocene global carbon (C) cycle and the rate of C sequestration and storage is driven by the balance between net primary productivity and decay. A number of studies now suggest that climate is a key driver of peatland C accumulation at large spatial scales and over long timescales, with warmer conditions associated with higher rates of C accumulation. However, other factors are also likely to play a significant role in determining local carbon accumulation rates and these may modify past, present and future peatland carbon sequestration. Here, we test the importance of climate as a driver of C accumulation, compared with hydrological change, fire, nitrogen content and vegetation type, from records of C accumulation at three sites in northeastern North America, across the N-S climate gradient of raised bog distribution. Radiocarbon age models, bulk density values and %C measurements from each site are used to construct C accumulation histories commencing between 11,200 and 8000 cal. years BP. The relationship between C accumulation and environmental variables (past water table depth, fire, peat forming vegetation and nitrogen content) is assessed with linear and multivariate regression analyses. Differences in long-term rates of carbon accumulation between sites support the contention that a warmer climate with longer growing seasons results in faster rates of long-term carbon accumulation. However, mid-late Holocene accumulation rates show divergent trends, decreasing in the north but rising in the south. We hypothesise that sites close to the moisture threshold for raised bog distribution increased their growth rate in response to a cooler climate with lower evapotranspiration in the late Holocene, but net primary productivity declined over the same period in northern areas causing a decrease in C accumulation. There was no clear relationship between C accumulation and hydrological change, vegetation, nitrogen content

  7. Peatland-GHG emissions in Europe

    NASA Astrophysics Data System (ADS)

    Droesler, Matthias

    2013-04-01

    Managed peatlands are hot spots for CO2, CH4 and N2O emissions. GHG which have been not fully integrated in past European climate projects. Peatlands contribute to European GHG emissions 10 times more per unit area than other terrestrial ecosystems. Peatland management and exploration by drainage, agricultural use and peat extraction turned pristine peatland GHG sinks into sources. Emissions can reach more than 40 t CO2equiv. ha-1 a-1 in intensively managed peatlands. On the other hand, the restoration of degraded peatlands does normally reduce these emissions significantly towards climate neutral levels, once the restoration work is done wisely. But in some cases the net climate effect do not decrease significantly depending on hydrological regimes, fertilization status of the peatlands, climate and vegetation type. In many European countries with significant peatland cover nationally funded projects were set up to investigate peatland GHG fluxes and their drivers. These scattered data and knowledge are currently being brought together under the coverage of the GHG-Europe project (Grant agreement no.: 244122) within a new synthesis to develop the relevant EF, identify the drivers and develop upscaling options for GHG-emissions. The talk will: (1) show a first cut of new Emission Factors for peatlands in Europe and compare these with IPCC-default values. (2) discuss the developed sensible response functions for GHG-fluxes against natural and anthropogenic drivers such as land use intensity, land management with drainage and climate variability. (3) show case studies from Germany show the applicability of response functions for upscaling of GHG-balances. (4) An outlook is given to the future European peatland GHG-Balance.

  8. A novel isolate and widespread abundance of the candidate alphaproteobacterial order (Ellin 329), in southern Appalachian peatlands.

    PubMed

    Harbison, Austin B; Carson, Michael A; Lamit, Louis J; Basiliko, Nathan; Bräuer, Suzanna L

    2016-08-01

    Peatlands of all latitudes play an integral role in global climate change by serving as a carbon sink and a primary source of atmospheric methane; however, the microbial ecology of mid-latitude peatlands is vastly understudied. Herein, next generation Illumina amplicon sequencing of small subunit rRNA genes was utilized to elucidate the microbial communities in three southern Appalachian peatlands. In contrast to northern peatlands, Proteobacteria dominated over Acidobacteria in all three sites. An average of 11 bacterial phyla was detected at relative abundance values >1%, with three candidate divisions (OP3, WS3 and NC10) represented, indicating high phylogenetic diversity. Physiological traits of isolates within the candidate alphaproteobacterial order, Ellin 329, obtained here and in previous studies indicate that bacteria of this order may be involved in hydrolysis of poly-, di- and monosaccharides. Community analyses indicate that Ellin 329 is the third most abundant order and is most abundant near the surface layers where plant litter decomposition should be primarily occurring. In sum, members of Ellin 329 likely play important roles in organic matter decomposition, in southern Appalachian peatlands and should be investigated further in other peatlands and ecosystem types. PMID:27302469

  9. Mechanisms for the suppression of methane production in peatland soils by a humic substance analog

    NASA Astrophysics Data System (ADS)

    Ye, R.; Keller, J. K.; Jin, Q.; Bohannan, B. J. M.; Bridgham, S. D.

    2014-01-01

    Methane (CH4) production is often impeded in many northern peatland soils, although inorganic terminal electron acceptors (TEAs) are usually present in low concentrations in these soils. Recent studies suggest that humic substances in wetland soils can be utilized as organic TEAs for anaerobic respiration and may directly inhibit CH4 production. Here we utilize the humic analog anthraquinone-2, 6-disulfonate (AQDS) to explore the importance of humic substances, and their effects on the temperature sensitivity of anaerobic decomposition, in two peatland soils. In a bog peat, AQDS was not instantly utilized as a TEA, but greatly inhibited the fermentative production of acetate, carbon dioxide (CO2), and hydrogen (H2), as well as CH4 production. When added together with glucose, AQDS was partially reduced after a lag period of 5 to 10 days. In contrast, no inhibitory effect of AQDS on fermentation was found in a fen peat and AQDS was readily reduced as an organic TEA. The addition of glucose and AQDS to both bog and fen peats caused complicated temporal dynamics in the temperature sensitivity of CH4 production, reflecting temporal changes in the temperature responses of other carbon processes with effects on methanogenesis. Our results show that the humic analog AQDS can act both as an inhibitory agent and a TEA in peatland soils. The high concentrations of humic substances in northern peatlands may greatly influence the effect of climate change on soil carbon cycling in these ecosystems.

  10. Tropical/Subtropical Peatland Development and Global CH4 during the Last Glaciation

    PubMed Central

    Xu, Hai; Lan, Jianghu; Sheng, Enguo; Liu, Yong; Liu, Bin; Yu, Keke; Ye, Yuanda; Cheng, Peng; Qiang, Xiaoke; Lu, Fengyan; Wang, Xulong

    2016-01-01

    Knowledge of peatland development over the tropical/subtropical zone during the last glaciation is critical for understanding the glacial global methane cycle. Here we present a well-dated ‘peat deposit-lake sediment’ alternate sequence at Tengchong, southwestern China, and discuss the peatland development and its linkage to the global glacial methane cycle. Peat layers were formed during the cold Marine Isotope Stage (MIS)-2 and -4, whereas lake sediments coincided with the relatively warm MIS-3, which is possibly related to the orbital/suborbital variations in both temperature and Asian summer monsoon intensity. The Tengchong peatland formation pattern is broadly synchronous with those over subtropical southern China and other tropical/subtropical areas, but it is clearly in contrast to those over the mid-high Northern Hemisphere. The results of this work suggest that the shifts of peatland development between the tropical/subtropical zone and mid-high Northern Hemisphere may have played important roles in the glacial/interglacial global atmospheric CH4 cycles. PMID:27465566

  11. Tropical/Subtropical Peatland Development and Global CH4 during the Last Glaciation

    NASA Astrophysics Data System (ADS)

    Xu, Hai; Lan, Jianghu; Sheng, Enguo; Liu, Yong; Liu, Bin; Yu, Keke; Ye, Yuanda; Cheng, Peng; Qiang, Xiaoke; Lu, Fengyan; Wang, Xulong

    2016-07-01

    Knowledge of peatland development over the tropical/subtropical zone during the last glaciation is critical for understanding the glacial global methane cycle. Here we present a well-dated ‘peat deposit-lake sediment’ alternate sequence at Tengchong, southwestern China, and discuss the peatland development and its linkage to the global glacial methane cycle. Peat layers were formed during the cold Marine Isotope Stage (MIS)-2 and -4, whereas lake sediments coincided with the relatively warm MIS-3, which is possibly related to the orbital/suborbital variations in both temperature and Asian summer monsoon intensity. The Tengchong peatland formation pattern is broadly synchronous with those over subtropical southern China and other tropical/subtropical areas, but it is clearly in contrast to those over the mid-high Northern Hemisphere. The results of this work suggest that the shifts of peatland development between the tropical/subtropical zone and mid-high Northern Hemisphere may have played important roles in the glacial/interglacial global atmospheric CH4 cycles.

  12. Tropical/Subtropical Peatland Development and Global CH4 during the Last Glaciation.

    PubMed

    Xu, Hai; Lan, Jianghu; Sheng, Enguo; Liu, Yong; Liu, Bin; Yu, Keke; Ye, Yuanda; Cheng, Peng; Qiang, Xiaoke; Lu, Fengyan; Wang, Xulong

    2016-01-01

    Knowledge of peatland development over the tropical/subtropical zone during the last glaciation is critical for understanding the glacial global methane cycle. Here we present a well-dated 'peat deposit-lake sediment' alternate sequence at Tengchong, southwestern China, and discuss the peatland development and its linkage to the global glacial methane cycle. Peat layers were formed during the cold Marine Isotope Stage (MIS)-2 and -4, whereas lake sediments coincided with the relatively warm MIS-3, which is possibly related to the orbital/suborbital variations in both temperature and Asian summer monsoon intensity. The Tengchong peatland formation pattern is broadly synchronous with those over subtropical southern China and other tropical/subtropical areas, but it is clearly in contrast to those over the mid-high Northern Hemisphere. The results of this work suggest that the shifts of peatland development between the tropical/subtropical zone and mid-high Northern Hemisphere may have played important roles in the glacial/interglacial global atmospheric CH4 cycles. PMID:27465566

  13. Carbon Sequestration and Peat Accretion Processes in Peatland Systems: A North-South Comparison

    NASA Astrophysics Data System (ADS)

    Richardson, C. J.; Wang, H.; Bridgham, S. D.

    2012-12-01

    Millions of hectares of peatlands exist in the U.S. and Canada but few comparisons have been made on the process controlling peat accretion, carbon sequestration and GHG losses across latitudinal gradients. Historic threats to carbon sequestration for these areas have been drainage and conversion to agriculture and forestry, which promotes the decomposition of the organic matter in the soil, leading to accelerated soil subsidence, severe carbon losses, and accelerated transport of C and nutrients to adjoining ecosystems. A more recent and insidious threat to the survival of peatlands worldwide is the increased temperature and drought conditions projected for many areas of global peatlands (IPCC 2007). A comparison of carbon sequestration rates and controlling processes for southeastern shrub bogs, the Florida Everglades and selected peatlands of the northern US and Canada under current climatic conditions reveals several major differences in controlling factors and rates of sequestration and carbon flux. Numerous studies have shown that drought or drainage can unlock historically stored carbon, thus releasing more CO2 ¬ and dissolved organic carbon (Blodau et al. 2004; Furukawa et al. 2005; Von Arnold et al. 2005; Hirano et al. 2007), and such effects might last for decades (Fenner & Freeman 2011). The main driver of this process is the O2 introduced by drought or drainage, which will increase the activity of phenol oxidase, then accelerate the decomposition of phenol compounds, which is generally considered the "enzymatic latch" for carbon storage in peatlands (Freeman et al. 2001). However, our recent studies in southeastern peatlands along the coast of North Carolina have found that drought or drainage does not affect CO2 emission in some southern peatlands where the initial water level is below the ground surface (unsaturated peats), as polyphenol increases rather than decreases. Our results suggest that additional controlling factors, rather than anoxia exist

  14. SPRUCE: Spruce and Peatland Responses under Climatic and Environmental Change

    DOE Data Explorer

    SPRUCE is an experiment to assess the response of northern peatland ecosystems to increases in temperature and exposures to elevated atmospheric CO2 concentrations. It is the primary component of the Terrestrial Ecosystem Science Scientific Focus Area of ORNL's Climate Change Program, focused on terrestrial ecosystems and the mechanisms that underlie their responses to climatic change. The experimental work is to be conducted in a Picea mariana [black spruce] - Sphagnum spp. bog forest in northern Minnesota, 40 km north of Grand Rapids, in the USDA Forest Service Marcell Experimental Forest (MEF). The site is located at the southern margin of the boreal peatland forest. It is an ecosystem considered especially vulnerable to climate change, and anticipated to be near its tipping point with respect to climate change. Responses to warming and interactions with increased atmospheric CO2 concentration are anticipated to have important feedbacks on the atmosphere and climate, because of the high carbon stocks harbored by such ecosystems.[copied from http://mnspruce.ornl.gov/] While some data files are restricted to access by project members only, others are available for public download now, even as research is being actively conducted.

  15. Environmental control of methane fluxes over a Danish peatland

    NASA Astrophysics Data System (ADS)

    Herbst, M.; Ringgaard, R.; Friborg, T.; Soegaard, H.

    2009-12-01

    Reducing the greenhouse gas (GHG) emissions from natural and anthropogenic environments has become a key issue over the last decades. In Denmark the management of the wetlands is playing a key role in these attempts. The wetland area of Skjern Meadows in the western part of Denmark is one of the best known examples of peatland restauration in northern Europe. The valley of the Skjern river was restored in 2002, after it had been drained for about 35 years. A micrometeorological instrument mast was erected in the centre of the 2200 ha large area in the summer of 2008, in order to facilitate continuous eddy covariance measurements of the exchange of carbon dioxide and methane between the peatland and the atmosphere. A sonic anemometer (R3, Gill) was used together with a closed-path CO2 analyzer (LI-7000, Li-Cor) and a closed-path CH4 analyzer (DLT-100, Los Gatos). A measurement height of 7 m above the surface ensures that the observed eddy fluxes represent an average signal from the entire peatland. The first year of data collection confirmed the expectation that the area functions as a moderate CO2 sink, whilst it releases methane into the atmosphere. During a 12-months period starting in September 2008, the wetland removed 119 g CO2-C per m2 from the atmosphere and emitted 6 g CH4-C per m2. If the amount of the emitted CH4 is converted into CO2 equivalents, it remained lower than the annual CO2 uptake (188 versus 437 g CO2). This means that the restored peatland functions as a weak greenhouse gas sink, despite its methane production. Whilst the annual CO2 uptake at Skjern Meadows was similar to that reported by Friborg et al. (2003) for a Siberian wetland, the CH4 emission was much lower. The average CO2 and CH4 flux rates were both lower than those estimated for a Dutch wetland by Hendriks et al. (2007). The CH4 emission showed no particular diurnal pattern, but daily rates varied considerably throughout the year. This variability can be correlated to variations

  16. Vulnerability of North American Boreal Peatlands to Interactions between Climate, Hydrology, and Wildland Fires

    NASA Astrophysics Data System (ADS)

    Bourgeau-Chavez, L. L.; Jenkins, L. K.; Kasischke, E. S.; Turetsky, M.; Benscoter, B.; Banda, E. J.; Boren, E. J.; Endres, S. L.; Billmire, M.

    2013-12-01

    North American boreal peatland sites of Alaska, Alberta Canada, and the southern limit of the boreal ecoregion (Michigan's Upper Peninsula) are the focus of an ongoing project to better understand the fire weather, hydrology, and climatic controls on boreal peatland fires. The overall goal of the research project is to reduce uncertainties of the role of northern high latitude ecosystems in the global carbon cycle and to improve carbon emission estimates from boreal fires. Boreal peatlands store tremendous reservoirs of soil carbon that are likely to become increasingly vulnerable to fire as climate change lowers water tables and exposes C-rich peat to burning. Increasing fire activity in peatlands could cause these ecosystems to become net sources of C to the atmosphere, which is likely to have large influences on atmospheric carbon concentrations through positive feedbacks that enhance climate warming. Remote sensing is key to monitoring, understanding and quantifying changes occurring in boreal peatlands. Remote sensing methods are being developed to: 1) map and classify peatland cover types; 2) characterize seasonal and inter-annual variations in the moisture content of surface peat (fuel) layers; 3) map the extent and seasonal timing of fires in peatlands; and 4) discriminate different levels of fuel consumption/burn severity in peat fires. A hybrid radar and optical infrared methodology has been developed to map peatland types (bog vs. fen) and level of biomass (open herbaceous, shrubby, forested). This methodology relies on multi-season data to detect phenological changes in hydrology which characterize the different ecosystem types. Landsat data are being used to discriminate burn severity classes in the peatland types using standard dNBR methods as well as individual bands. Cross referencing the peatland maps and burn severity maps will allow for assessment of the distribution of upland and peatland ecosystems affected by fire and quantitative analysis of

  17. Water repellency diminishes peatland evaporation after wildfire

    NASA Astrophysics Data System (ADS)

    Kettridge, N.; Lukenbach, M.; Hokanson, K. J.; Devito, K. J.; Petrone, R. M.; Hopkinson, C.; Waddington, J. M.

    2015-12-01

    Peatlands are a critically important global carbon reserve. There is increasing concern that such ecosystems are vulnerable to projected increases in wildfire severity under a changing climate. Severe fires may exceed peatland ecological resilience resulting in the long term degradation of this carbon store. Evaporation provides the primary mechanisms of water loss from such environments and can regulate the ecological stress in the initial years after wildfire. We examine variations in evaporation within burned peatlands after wildfire through small scale chamber and large scale remote sensing measurements. We show that near-surface water repellency limits peatland evaporation in these initial years post fire. Water repellent peat produced by the fire restricts the supply of water to the surface, reducing evaporation and providing a strong negative feedback to disturbance. This previously unidentified feedback operates at the landscape scale. High surface temperatures that result from large reductions in evaporation within water repellent peat are observed across the 60,000 ha burn scar three months after the wildfire. This large scale reduction in evaporation promotes high water table positions at a landscape scale which limits the rate of peat decomposition and supports the post fire ecohydrological recovery of the peatlands. However, severe burns are shown to exceed this negative feedback response. Deep burns at the peatland margins remove the hydrophobic layer, increasing post fire evaporation and leaving the peatland vulnerable to drying and associated ecological shifts.

  18. Water repellency diminishes peatland evaporation after wildfire

    NASA Astrophysics Data System (ADS)

    Kettridge, Nick; Lukenbach, Max; Hokanson, Kelly; Devito, Kevin; Hopkinson, Chris; Petrone, Rich; Mendoza, Carl; Waddington, Mike

    2016-04-01

    Peatlands are a critically important global carbon reserve. There is increasing concern that such ecosystems are vulnerable to projected increases in wildfire severity under a changing climate. Severe fires may exceed peatland ecological resilience resulting in the long term degradation of this carbon store. Evaporation provides the primary mechanisms of water loss from such environments and can regulate the ecological stress in the initial years after wildfire. We examine variations in evaporation within burned peatlands after wildfire through small scale chamber and large scale remote sensing measurements. We show that near-surface water repellency limits peatland evaporation in these initial years post fire. Water repellent peat produced by the fire restricts the supply of water to the surface, reducing evaporation and providing a strong negative feedback to disturbance. This previously unidentified feedback operates at the landscape scale. High surface temperatures that result from large reductions in evaporation within water repellent peat are observed across the 60,000 ha burn scar three months after the wildfire. This promotes high water table positions at a landscape scale which limit the rate of peat decomposition and supports the post fire ecohydrological recovery of the peatlands. However, severe burns are shown to exceed this negative feedback response. Deep burns at the peatland margins remove the hydrophobic layer, increasing post fire evaporation and leaving the peatland vulnerable to drying and associated ecological shifts.

  19. Methane emissions from a peatland following restoration

    NASA Astrophysics Data System (ADS)

    Waddington, J. M.; Day, S. M.

    2007-09-01

    Peatland drainage and peat extraction changes natural peatlands from a net carbon sink to that of a large net source due to increased respiration and the removal of carbon dioxide (CO2) fixing vegetation. Restoration of these altered peatland ecosystems is being applied to reduce these carbon emissions. As peatland restoration is a new and emerging land-use management practice, the purpose of this research was to examine the impact of restoration on the methane (CH4) component of the carbon cycle at the Bois-des-Bel peatland located near Rivière-du-Loup, Québec from early May to mid October for several years. The seasonal CH4 fluxes prior to restoration at an extracted (cutover) and a restored peatland were not significantly different from each other or zero. However, three years postrestoration the seasonal CH4 emissions at the restored site were 4.2 g m-2 CH4 season-1, 4.6 times greater than the cutover site. Ponds and ditches at the restored site were seasonal CH4 emission hot spots (0.3 and 2.9 g m-2 CH4 season-1, respectively); however, emissions from herbaceous vegetation (1.0 g m-2 CH4 season-1) were the dominant source of CH4 from the restored peatland due to its large areal extent. CH4 fluxes from the Bois-des-Bel peatland represented 14% of the total CO2-equivalent losses from the site. This study demonstrates the importance of vegetation succession on peatland-atmosphere flux of CH4.

  20. Bacterial production in subarctic peatland lakes enriched by thawing permafrost

    NASA Astrophysics Data System (ADS)

    Deshpande, Bethany N.; Crevecoeur, Sophie; Matveev, Alex; Vincent, Warwick F.

    2016-08-01

    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 (> 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 > 3 µm. This relatively low contribution of free-living cells (operationally defined as the < 1 µm fraction) to bacterial production was a general

  1. Methane Production in Minnesota Peatlands

    PubMed Central

    Williams, Richard T.; Crawford, Ronald L.

    1984-01-01

    Rates of methane production in Minnesota peats were studied. Surface (10- to 25-cm) peats produced an average of 228 nmol of CH4 per g (dry weight) per h at 25°C and ambient pH. Methanogenesis rates generally decreased with depth in ombrotrophic peats, but on occasion were observed to rise within deeper layers of certain fen peats. Methane production was temperature dependent, increasing with increasing temperature (4 to 30°C), except in peats from deeper layers. Maximal methanogenesis from these deeper regions occurred at 12°C. Methane production rates were also pH dependent. Two peats with pHs of 3.8 and 4.3 had an optimum rate of methane production at pH 6.0. The addition to peat of glucose and H2-CO2 stimulated methanogenesis, whereas the addition of acetate inhibited methanogenesis. Cysteine-sulfide, nitrogen-phosphorus-trace metals, and vitamins-yeast extract affected methane production very little. Various gases were found to be trapped or dissolved (or both) within peatland waters. Dissolved methane increased linearly to a depth of 210 cm. The accumulation of metabolic end products produced within peat bogs appears to be an important mechanism limiting carbon turnover in peatland environments. PMID:16346565

  2. Methane production in Minnesota peatlands

    SciTech Connect

    Williams, R.T.; Crawford, R.L.

    1984-06-01

    Rates of methane production in Minnesota peats were studied. Surface (10- to 25-cm) peats produced an average of 228 nmol of CH/sub 4/ per g (dry weight) per h at 25/sup 0/C and ambient pH. Methanogenesis rates generally decreased with depth in ombrotrophic peats, but on occasion were observed to rise within deeper layers of certain fen peats. Methane production was temperature dependent, increasing with increasing temperature (4 to 30/sup 0/C), except in peats from deeper layers. Maximal methanogenesis from these deeper regions occurred at 12/sup 0/C. Methane production rates were also pH dependent. Two peats with pHs of 3.8 and 4.3 had an optimum rate of methane production at pH 6.0. The addition to peat of glucose and H/sub 2/-CO/sub 2/ stimulated methanogenesis, whereas the addition of acetate inhibited methanogenesis. Cysteine-sulfide, nitrogen-phosphorus-trace metals, and vitamins-yeast extract affected methane production very little. Various gases were found to be trapped or dissolved (or both) within peatland waters. Dissolved methane increased linearly to a depth of 210 cm. The accumulation of metabolic end products produced within peat bogs appears to be an important mechanism limiting turnover in peatland environments.

  3. Paludiculture as a chance for peatland and climate: the greenhouse gas balance of biomass production on two rewetted peatlands does not differ from the natural state

    NASA Astrophysics Data System (ADS)

    Günther, Anke; Huth, Vytas; Jurasinski, Gerald; Albrecht, Kerstin; Glatzel, Stephan

    2015-04-01

    In Europe, rising prices for farm land make it increasingly difficult for government administrations to compete with external investors during the acquisition of land for wetland conservation. Thus, adding economic value to these, otherwise "lost", areas by combining extensive land use with nature conservation efforts could increase the amount of ground available for wetland restoration. Against this background, the concept of paludiculture aims to provide biomass for multiple purposes from peatlands with water tables high enough to conserve the peat body. However, as plants have been shown to contribute to greenhouse gas exchange in peatlands, manipulating the vegetation (by harvesting, sowing etc.) might alter the effect of the restored peatlands on climate. Here, we present greenhouse gas data from two experimental paludiculture systems on formerly drained intensive grasslands in northern Germany. In a fen that has been rewetted more than 15 years ago three species of reed plants were harvested to simulate biomass production for bioenergy and as construction material. And in a peat bog that has been converted from drained grassland to a field with a controlled water table around ground surface Sphagnum mosses were cultivated to provide an alternative growing substrate for horticulture. In both systems, we determined carbon dioxide, methane, and nitrous oxide exchange using closed chambers over two years. Additionally, water and peat chemistry and environmental parameters as recorded by a weather station were analyzed. Both restored peatlands show greenhouse gas balances comparable to those of natural ecosystems. Nitrous oxide was not emitted in either system. Fluctuations of the emissions reflect changes in weather conditions across the study years. In the fen, relative emission patterns between plant species were not constant over time. We did not find a negative short-term effect of biomass harvest or Sphagnum cultivation on net greenhouse gas balances

  4. Peatland Microbial Communities and Decomposition Processes in the James Bay Lowlands, Canada

    PubMed Central

    Preston, Michael D.; Smemo, Kurt A.; McLaughlin, James W.; Basiliko, Nathan

    2012-01-01

    Northern peatlands are a large repository of atmospheric carbon due to an imbalance between primary production by plants and microbial decomposition. The James Bay Lowlands (JBL) of northern Ontario are a large peatland-complex but remain relatively unstudied. Climate change models predict the region will experience warmer and drier conditions, potentially altering plant community composition, and shifting the region from a long-term carbon sink to a source. We collected a peat core from two geographically separated (ca. 200 km) ombrotrophic peatlands (Victor and Kinoje Bogs) and one minerotrophic peatland (Victor Fen) located near Victor Bog within the JBL. We characterized (i) archaeal, bacterial, and fungal community structure with terminal restriction fragment length polymorphism of ribosomal DNA, (ii) estimated microbial activity using community level physiological profiling and extracellular enzymes activities, and (iii) the aeration and temperature dependence of carbon mineralization at three depths (0–10, 50–60, and 100–110 cm) from each site. Similar dominant microbial taxa were observed at all three peatlands despite differences in nutrient content and substrate quality. In contrast, we observed differences in basal respiration, enzyme activity, and the magnitude of substrate utilization, which were all generally higher at Victor Fen and similar between the two bogs. However, there was no preferential mineralization of carbon substrates between the bogs and fens. Microbial community composition did not correlate with measures of microbial activity but pH was a strong predictor of activity across all sites and depths. Increased peat temperature and aeration stimulated CO2 production but this did not correlate with a change in enzyme activities. Potential microbial activity in the JBL appears to be influenced by the quality of the peat substrate and the presence of microbial inhibitors, which suggests the existing peat substrate will have a large

  5. The Tintah-Campbell gap and implications for glacial Lake Agassiz drainage during the Younger Dryas cold interval

    NASA Astrophysics Data System (ADS)

    Breckenridge, Andy

    2015-06-01

    Reconstructions of glacial Lake Agassiz paleogeography and drainage have been an important contribution to formulating a hypothesis in which glacial Lake Agassiz drainage to the Atlantic Ocean initiated the Younger Dryas cold interval. This study evaluates the lake level and outlet history of Lake Agassiz as recorded by strandlines visible on lidar digital elevation models from North Dakota and Minnesota. The former lake levels are warped due to glacial isostatic adjustment. Older levels have experienced more uplift and therefore have more curvature. The strandline data establish that the Moorhead lowstand of Lake Agassiz was bracketed by the strongly diverging Campbell and Tintah lake levels, which creates a vertical gap between the former lake levels. This gap exists due to a lake level drop of ˜90 m when the Laurentide Ice Sheet retreat opened a lower outlet, which must have been a northwest outlet to the Arctic Ocean. By applying an exponential decay rebound model, this event dates to 12,180 ± 480 cal yr BP, post-dating the beginning of the Younger Dryas at 12,900 cal yr BP. Eastern drainage outlets to the Atlantic Ocean through the Laurentian Great Lakes that were contemporaneous with the onset of the Younger Dryas cannot be ruled out, but if these outlets existed, their duration of occupation was short-lived and not characterized by significant drawdown events within glacial Lake Agassiz.

  6. Analyzing peatland discharge to streams in an Alaskan watershed: An integration of end-member mixing analysis and a water balance approach

    NASA Astrophysics Data System (ADS)

    Gracz, Michael B.; Moffett, Mary F.; Siegel, Donald I.; Glaser, Paul H.

    2015-11-01

    Peatlands are the dominant landscape element in many northern watersheds where they can have an important influence on the hydrology of streams. However, the capacity of peatlands to moderate stream flow during critical dry periods remains uncertain partly due to the difficulty of estimating discharge from extensive peat deposits. We therefore used two different approaches to quantify diffuse pore water contributions from peatlands to a creek within a small watershed in Southcentral Alaska. A sensitivity analysis of a water budget for a representative peatland within this watershed showed that a substantial surplus of pore water may remain available for subsequent discharge during a dry period after accounting for water losses to evapotranspiration. These findings were supported by end member mixing analysis (EMMA), which indicated that 55% of the stream flow during a dry period originated from the near-surface layers of peatlands within the watershed. Contributions from peatlands to stream flow in northern coastal regions may therefore provide an important buffer against the potentially harmful effects of changing climatic conditions on commercially important fish species.

  7. Isotopic composition of Lake Agassiz-Ojibway water just prior to final drainage

    NASA Astrophysics Data System (ADS)

    Hillaire-Marcel, C.; Helie, J.; McKay, J.; Lalonde, A.

    2006-12-01

    Controversies persist with respect to the impact of the final drainage of Lake Agassiz-Ojibway on the thermohaline circulation of the North Atlantic, some 8.4 ka ago. The lack of response of planktic foraminifer isotope records, off Hudson Strait (i.e., at the outlet of the drainage channel) constitutes one of the most puzzling elements in this debate. However, data on the isotopic composition of drainage waters are needed to estimate the response of the 18-O-salinity relationship in NW Atlantic surface waters. In the literature, a large array of isotopic compositions have been suggested, notably for modeling experiment purposes. Scattered information about the isotopic composition of Lake Agassiz water does exist. It includes isotopic measurements of pore waters of lacustrine sediments [1], analyses of oxygen isotopes in cellulose from algal or plant remains [2], and stable isotope compositions of concretions from varves [3]. Whereas, relatively low oxygen isotope values (apx. -25 per mil vs. VSMOW) are inferred for Lake Agassiz waters during cold pulses of the deglaciation, most data suggest much higher values during the final stages of Lake Agassiz-Ojiway, just prior to its drainage. Calcareous concretions from Lake Ojibway varves (not necessarily contemporaneous to the lacustrine stage) yielded oxygen isotope compositions of about -10 per mil (vs. VPDB), suggesting values as high as -14 per mil (vs. VSMOW) for pore waters (assuming a 0-4 degrees C temperature range). Similar high values (as high as -8 per mil vs. VSMOW [1]) were also estimated from pore water analyses of contemporaneous Lake Agassiz sediments. Here, we used a core raised from Eastern Hudson Bay, off Great Whale River, to further document isotopic compositions of the lake waters prior to their drainage into the North Atlantic. The 7.40 m long core has an apx. 1.3 m-thick lacustrine layer at its base, including the drainage sub- layer. It is overlain by Tyrrell Sea clays. Scarce valves of Candona

  8. Modelling Holocene peatland and permafrost dynamics with the LPJ-GUESS dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Chaudhary, Nitin; Miller, Paul A.; Smith, Benjamin

    2016-04-01

    Dynamic global vegetation models (DGVMs) are an important platform to study past, present and future vegetation patterns together with associated biogeochemical cycles and climate feedbacks (e.g. Sitch et al. 2008, Smith et al. 2001). However, very few attempts have been made to simulate peatlands using DGVMs (Kleinen et al. 2012, Tang et al. 2015, Wania et al. 2009a). In the present study, we have improved the peatland dynamics in the state-of-the-art dynamic vegetation model (LPJ-GUESS) in order to understand the long-term evolution of northern peatland ecosystems and to assess the effect of changing climate on peatland carbon balance. We combined a dynamic multi-layer approach (Frolking et al. 2010, Hilbert et al. 2000) with soil freezing-thawing functionality (Ekici et al. 2015, Wania et al. 2009a) in LPJ-GUESS. The new model is named LPJ-GUESS Peatland (LPJ-GUESS-P) (Chaudhary et al. in prep). The model was calibrated and tested at the sub-arctic mire in Stordalen, Sweden, and the model was able to capture the reported long-term vegetation dynamics and peat accumulation patterns in the mire (Kokfelt et al. 2010). For evaluation, the model was run at 13 grid points across a north to south transect in Europe. The modelled peat accumulation values were found to be consistent with the published data for each grid point (Loisel et al. 2014). Finally, a series of additional experiments were carried out to investigate the vulnerability of high-latitude peatlands to climate change. We find that the Stordalen mire will sequester more carbon in the future due to milder and wetter climate conditions, longer growing seasons, and the carbon fertilization effect. References: - Chaudhary et al. (in prep.). Modelling Holocene peatland and permafrost dynamics with the LPJ-GUESS dynamic vegetation model - Ekici A, et al. 2015. Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes. The Cryosphere 9: 1343

  9. Plant phenology and composition controls of carbon fluxes in a boreal peatland

    NASA Astrophysics Data System (ADS)

    Peichl, Matthias; Gažovič, Michal; Vermeij, Ilse; De Goede, Eefje; Sonnentag, Oliver; Limpens, Juul; Nilsson, Mats B.

    2016-04-01

    Vegetation drives the peatland carbon (C) cycle via the processes of photosynthesis, plant respiration and decomposition as well as by providing substrate for methane (CH4) and dissolved organic carbon production. However, due to the lack of comprehensive vegetation data, variations in the peatland C fluxes are commonly related to temperature and other more easily measured abiotic (i.e. weather and soil) variables. Due to the temporal co-linearity between plant development and abiotic variables, these relationships may describe the variations in C fluxes reasonably well, however, without representing the true mechanistic processes driving the peatland C cycle. As a consequence, current process-based models are poorly parameterized and unable to adequately predict the responses of the peatland C cycle to climate change, extreme events and anthropogenic impacts. To fill this knowledge gap, we explored vegetation phenology and composition effects on the peatland C cycle at the Degerö peatland located in northern Sweden. We used a greenness index derived from digital repeat photography to quantitatively describe plant canopy development with high temporal (i.e. daily) and spatial (plot to ecosystem) resolution. In addition, eddy covariance and static chamber measurements of carbon dioxide (CO2) and CH4 fluxes over an array of vegetation manipulation plots were conducted over multiple years. Our results suggest that vascular plant phenology controls the onset and pattern of eddy covariance-derived gross primary production (GPP) during the spring period, while abiotic conditions modify GPP during the summer period when plant canopy cover is fully developed. Inter-annual variations in the spring onset and patterns of plant canopy development were best explained by differences in the preceding growing degree day sum. We also observed strong correlations of canopy greenness with the net ecosystem CO2 exchange and ecosystem respiration. On average, vascular plant and moss

  10. Linkage among Vegetation, Microbes and Methanogenic Pathways in Alaskan Peatlands

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Sidelinger, W.; Shu, H.; Varner, R. K.; Hines, M. E.

    2014-12-01

    Northern wetlands are thought to account for one third of the naturally emitted CH4. However, methane production pathways in northern peatlands are poorly understood, yet are predicted to change in response to vegetation shifts due to warming. Previous studies noted that acetate conversion to methane (acetoclastic methanogenesis, AM) in northern wetlands is largely impeded and acetate accumulates, however AM tends to increase with minerotrophy. To understand methanogenic pathways and to provide linkage among pathways, we studied Alaskan wetlands in 2013 and 2014. In 2013, laboratory incubations were conducted in three peatlands representing trophic gradients from bogs to fens. During 2014, 37 different sites in Fairbanks and Anchorage were studied that represented wetlands with pH values from 3.5 to 5.5 and vegetation from primarily Sphagnum to sedges. Measurements in 2014 included vegetation composition, gases (CH4, CO2, H2, and CO), 13CH4 and 13CO2, volatile fatty acids, DOC, other electron acceptors. Further incubation studies are being conducted to decipher controls on decomposition pathways. Gene sequencing was used to characterize microbial community composition, and metagenomic and transcriptomics were conducted to describe community activity. Results showed that methanogenesis was higher in fens than bogs, but hydrogenotrophic methanogenesis (HM) was dominant at all sites. End product ratios showed that AM was occurring in fens, albeit slowly. Fermentation was an important end-point in decomposition and microbial syntrophy was weak. These data, regardless of trophic status, differed greatly from data obtained from temperate wetlands in which terminal respiratory processes were strong and C flow through syntrophy was important. Trophic status influenced C flow in the Alaskan sites, but terminal processes were weak and end product formation tended to end at primary fermentation, which dominated as the terminal step in decomposition.

  11. Factors affecting re-vegetation dynamics of experimentally restored extracted peatland in Estonia.

    PubMed

    Karofeld, Edgar; Müür, Mari; Vellak, Kai

    2016-07-01

    Increasing human activity continues to threaten peatlands, and as the area of natural mires declines, our obligation is to restore their ecosystem functions. Several restoration strategies have been developed for restoration of extracted peatlands, including "The moss layer transfer method", which was initiated on the Tässi extracted peatland in central Estonia in May 2012. Three-year study shows that despite the fluctuating water table, rainfall events can compensate for the insufficient moisture for mosses. Total plant cover on the restoration area attained 70 %, of which ~60 % is comprised of target species-Sphagnum mosses. From restoration treatments, spreading of plant fragments had a significant positive effect on the cover of bryophyte and vascular plants. Higher water table combined with higher plant fragments spreading density and stripping of oxidised peat layer affected positively the cover of targeted Sphagnum species. The species composition in the restoration area became similar to that in the donor site in a natural bog. Based on results, it was concluded that the method approved for restoration in North America gives good results also in the restoration of extracted peatland towards re-establishment of bog vegetation under northern European conditions. PMID:26490883

  12. Responsible management of peatlands in Canada, from peat industry to oil sands

    NASA Astrophysics Data System (ADS)

    Rochefort, Line

    2013-04-01

    Canada harbors one third of the peat resources of the world. Peat is an accumulated organic matter composed of dead and partly decomposed plant material, forming huge deposit through time in wetlands like peatlands and boreal coniferous swamps. Peat is a valuable resource as a growing media and soil amendments, an eco-friendly absorbent, also used as biofilters, for body care and for wastewater treatment. Peatlands also offer valuable ecological services : for example, they are the most efficient terrestrial ecosystem to store carbon on a long-term basis. Their ability to "cool off" the planet warrants a good look at their management. The horticultural peat industry of Canada has invested 22 years in R&D in habitat restoration and is now a strong leader in managing industrial peatlands in a sustainable way. The oil sand industry, which is strongly impacting the wetland landscapes of northern Canada, does realize that it has to reduce its ecological footprint, which is heavily criticized around the world. Decommissioned open mines near Fort McMurray have already begun recreating peatland ecosystems, and some restoration attempts of former oil pads are underway in the Peace River region. But the restoration of the largely disturbed wetland landscape of the oil sands is commanding innovative solutions.

  13. River Ecosystem Response to Prescribed Vegetation Burning on Blanket peatland

    PubMed Central

    Brown, Lee E.; Johnston, Kerrylyn; Palmer, Sheila M.; Aspray, Katie L.; Holden, Joseph

    2013-01-01

    Catchment-scale land-use change is recognised as a major threat to aquatic biodiversity and ecosystem functioning globally. In the UK uplands rotational vegetation burning is practised widely to boost production of recreational game birds, and while some recent studies have suggested burning can alter river water quality there has been minimal attention paid to effects on aquatic biota. We studied ten rivers across the north of England between March 2010 and October 2011, five of which drained burned catchments and five from unburned catchments. There were significant effects of burning, season and their interaction on river macroinvertebrate communities, with rivers draining burned catchments having significantly lower taxonomic richness and Simpson’s diversity. ANOSIM revealed a significant effect of burning on macroinvertebrate community composition, with typically reduced Ephemeroptera abundance and diversity and greater abundance of Chironomidae and Nemouridae. Grazer and collector-gatherer feeding groups were also significantly less abundant in rivers draining burned catchments. These biotic changes were associated with lower pH and higher Si, Mn, Fe and Al in burned systems. Vegetation burning on peatland therefore has effects beyond the terrestrial part of the system where the management intervention is being practiced. Similar responses of river macroinvertebrate communities have been observed in peatlands disturbed by forestry activity across northern Europe. Finally we found river ecosystem changes similar to those observed in studies of wild and prescribed forest fires across North America and South Africa, illustrating some potentially generic effects of fire on aquatic ecosystems. PMID:24278367

  14. Medium term ecohydrological response of peatland bryophytes to canopy disturbance

    NASA Astrophysics Data System (ADS)

    Leonard, Rhoswen; Kettridge, Nick; Krause, Stefan; Devito, Kevin; Granath, Gustaf; Petrone, Richard; Mandoza, Carl; Waddington, James Micheal

    2016-04-01

    Canopy disturbance in northern forested peatlands is widespread. Canopy changes impact the ecohydrological function of moss and peat, which provide the principal carbon store within these carbon rich ecosystems. Different mosses have contrasting contributions to carbon and water fluxes (e.g. Sphagnum fuscum and Pleurozium schreberi) and are strongly influenced by canopy cover. As a result, changes in canopy cover lead to long-term shifts in species composition and associated ecohydrological function. Despite this, the medium-term response to such disturbance, the associated lag in this transition to a new ecohydrological and biogeochemical regime, is not understood. Here we investigate this medium term ecohydrological response to canopy removal using a randomised plot design within a north Albertan peatland. We show no significant ecohydrological change in treatment plots four years after canopy removal. Notably, Pleurozium schreberi and Sphagnum fuscum remained within respective plots post treatment and there was no significant difference in plot resistance to evapotranspiration or carbon exchange. Our results show that canopy removal alone has little impact on bryophyte ecohydrology in the short/medium term. This resistance to disturbance contrasts strongly with dramatic short-term changes observed within mineral soils suggesting that concurrent shifts in the large scale hydrology induced within such disturbances are necessary to cause rapid ecohydrological transitions. Understanding this lagged response is critical to determine the decadal response of carbon and water fluxes in response to disturbance and the rate at which important medium term ecohydrological feedbacks are invoked.

  15. River ecosystem response to prescribed vegetation burning on Blanket Peatland.

    PubMed

    Brown, Lee E; Johnston, Kerrylyn; Palmer, Sheila M; Aspray, Katie L; Holden, Joseph

    2013-01-01

    Catchment-scale land-use change is recognised as a major threat to aquatic biodiversity and ecosystem functioning globally. In the UK uplands rotational vegetation burning is practised widely to boost production of recreational game birds, and while some recent studies have suggested burning can alter river water quality there has been minimal attention paid to effects on aquatic biota. We studied ten rivers across the north of England between March 2010 and October 2011, five of which drained burned catchments and five from unburned catchments. There were significant effects of burning, season and their interaction on river macroinvertebrate communities, with rivers draining burned catchments having significantly lower taxonomic richness and Simpson's diversity. ANOSIM revealed a significant effect of burning on macroinvertebrate community composition, with typically reduced Ephemeroptera abundance and diversity and greater abundance of Chironomidae and Nemouridae. Grazer and collector-gatherer feeding groups were also significantly less abundant in rivers draining burned catchments. These biotic changes were associated with lower pH and higher Si, Mn, Fe and Al in burned systems. Vegetation burning on peatland therefore has effects beyond the terrestrial part of the system where the management intervention is being practiced. Similar responses of river macroinvertebrate communities have been observed in peatlands disturbed by forestry activity across northern Europe. Finally we found river ecosystem changes similar to those observed in studies of wild and prescribed forest fires across North America and South Africa, illustrating some potentially generic effects of fire on aquatic ecosystems. PMID:24278367

  16. Assessment of nutrients and suspended sediment conditions in and near the Agassiz National Wildlife Refuge, Northwest Minnesota, 2008–2010

    USGS Publications Warehouse

    Nustad, Rochelle A.; Galloway, Joel M.

    2012-01-01

    In response to concerns about water-quality impairments that may affect habitat degradation in Agassiz National Wildlife Refuge in northwest Minnesota, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service collected streamflow data, discrete nutrient and suspended- sediment samples, and continuous water-quality data from 2008 to 2010. Constituent loads were estimated for nutrients and suspended sediment using sample data and streamflow data. In addition, a potential water-quality and streamflow monitoring program design was developed for Agassiz National Wildlife Refuge. Results from this study can be used by resource managers to address identified impairments and protect wildlife habitat and public water supply, and may contribute toward developing more effective water-management plans for Agassiz National Wildlife Refuge.

  17. Carbon dynamics in peatland pool systems: the role of light

    NASA Astrophysics Data System (ADS)

    Pickard, Amy; Heal, Kate; McLeod, Andy; Dinsmore, Kerry

    2016-04-01

    Open-water pools are widespread in peatlands and are considered to represent biogeochemical hotspots within the peatland landscape. However the contribution of pool systems to wider peatland C cycling has not been quantified fully and there is a lack of knowledge of the role of photochemical processes in such environments. In this study, light exposure experiments were conducted in two contrasting pools to test the reactivity of aquatic C. The first study site was located at Cross Lochs (CL), Forsinard, in the Flow Country of Northern Scotland, in a 412 m2 pool characterised by low dissolved organic carbon (DOC) concentrations (˜15 mg C L‑1). The second site was located at Red Moss of Balerno (RM), a raised bog in central Scotland, in a 48 m2 pool with high DOC concentrations (˜35 mg C L‑1). Experiments took place over 9 days in situ at each pool in mid-summer 2015, with 500 mL water samples contained in bags transparent to sunlight and in opaque control bags. After field exposure, optical, chemical and stable C isotope analyses were conducted on the samples. Significant differences in biogeochemical cycling of DOC were detected between the two systems, with DOC losses as a percentage of the total C pool 15% higher at RM than at CL after light exposure. The mean DOC concentration of light exposed samples at RM declined steeply initially, with 83% observed DOC degradation occurring by day 3 of the experiment. Total losses of 7.9 mg DOC L‑1were observed in light exposed samples at RM, along with decreasing E4:E6 ratios, suggesting that material remaining at the end of the experiment was humified. Depletion of DOC was positively correlated with production of CO2 at both sites, with concentrations of up to 4.3 mg CO2-C L‑1 recorded at RM. Stable C isotope signatures at both sites were altered under light treatment, as demonstrated by the production of enriched δ13C-DOC (+0.46 ‰ relative to opaque bags) and depleted δ13C-DIC (-0.97 ‰ relative to opaque

  18. Predicting soil respiration from peatlands.

    PubMed

    Rowson, J G; Worrall, F; Evans, M G; Dixon, S D

    2013-01-01

    This study considers the relative performance of six different models to predict soil respiration from upland peat. Predicting soil respiration is important for global carbon budgets and gap filling measured data from eddy covariance and closed chamber measurements. Further to models previously published new models are presented using two sub-soil zones and season. Models are tested using data from the Bleaklow plateau, southern Pennines, UK. Presented literature models include ANOVA using logged environmental data, the Arrhenius equation, modified versions of the Arrhenius equation to include soil respiration activation energy and water table depth. New models are proposed including the introduction of two soil zones in the peat profile, and season. The first new model proposes a zone of high CO(2) productivity related to increased soil microbial CO(2) production due to the supply of labile carbon from plant root exudates and root respiration. The second zone is a deeper zone where CO(2) production is lower with less labile carbon. A final model allows the zone of high CO(2) production to become dormant during winter months when plants will senesce and will vary depending upon vegetation type within a fixed location. The final model accounted for, on average, 31.9% of variance in net ecosystem respiration within 11 different restoration sites whilst, using the same data set, the best fitting literature equation only accounted for 18.7% of the total variance. Our results demonstrate that soil respiration models can be improved by explicitly accounting for seasonality and the vertically stratified nature of soil processes. These improved models provide an enhanced basis for calculating the peatland carbon budgets which are essential in understanding the role of peatlands in the global C cycle. PMID:23178842

  19. Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean.

    PubMed

    Murton, Julian B; Bateman, Mark D; Dallimore, Scott R; Teller, James T; Yang, Zhirong

    2010-04-01

    The melting Laurentide Ice Sheet discharged thousands of cubic kilometres of fresh water each year into surrounding oceans, at times suppressing the Atlantic meridional overturning circulation and triggering abrupt climate change. Understanding the physical mechanisms leading to events such as the Younger Dryas cold interval requires identification of the paths and timing of the freshwater discharges. Although Broecker et al. hypothesized in 1989 that an outburst from glacial Lake Agassiz triggered the Younger Dryas, specific evidence has so far proved elusive, leading Broecker to conclude in 2006 that "our inability to identify the path taken by the flood is disconcerting". Here we identify the missing flood path-evident from gravels and a regional erosion surface-running through the Mackenzie River system in the Canadian Arctic Coastal Plain. Our modelling of the isostatically adjusted surface in the upstream Fort McMurray region, and a slight revision of the ice margin at this time, allows Lake Agassiz to spill into the Mackenzie drainage basin. From optically stimulated luminescence dating we have determined the approximate age of this Mackenzie River flood into the Arctic Ocean to be shortly after 13,000 years ago, near the start of the Younger Dryas. We attribute to this flood a boulder terrace near Fort McMurray with calibrated radiocarbon dates of over 11,500 years ago. A large flood into the Arctic Ocean at the start of the Younger Dryas leads us to reject the widespread view that Agassiz overflow at this time was solely eastward into the North Atlantic Ocean. PMID:20360738

  20. Holocene peatland initiation in the Greater Everglades

    NASA Astrophysics Data System (ADS)

    Dekker, Stefan C.; Boer, Hugo J.; Dermody, Brian J.; Wagner-Cremer, Friederike; Wassen, Martin J.; Eppinga, Maarten B.

    2015-02-01

    The mechanisms involved in the initiation and development of the Greater Everglades peatland ecosystems remain a topic of discussion. In this study, we first present an overview of basal ages of peat deposits in South Florida, which shows two major episodes of peatland initiation between 7.0-4.5 kyr and 3.5-2.0 kyr. Our analysis of regional climate proxy data sets led to three alternative hypotheses that may explain the timing and duration of these two peatland initiation episodes: (1) decreased drainage due to relative sea level (RSL) rise during the Holocene, (2) gradual increase in precipitation throughout the Holocene, and (3) a combination of increasing precipitation, rising RSL, and oscillations in the climate system. We test whether these three hypotheses can explain the pattern of initiation and development of the Greater Everglades peatlands using models that simulate the nonlinear processes involved in peat production and decomposition. The model results suggest that RSL rise could explain the onset of peatland initiation and imply that the climate was wet enough for peat development also during the early Holocene. The first two hypothesized mechanisms in combination with climate oscillations may explain the onset of peat accumulation at 8.2 kyr B.P. The two-phased character of peatland initiation maybe explained by the spatial distribution of local drainage conditions. As peatland development is highly nonlinear, our model uncovers a mechanistic way how peats can suddenly shift from a dry high equilibrium to a wet low equilibrium resulting in lake formation as observed in paleoecological studies in the Greater Everglades.

  1. Changes in vascular plant functional types drive carbon cycling in peatlands

    NASA Astrophysics Data System (ADS)

    Zeh, Lilli; Bragazza, Luca; Erhagen, Björn; Limpens, Juul; Kalbitz, Karsten

    2016-04-01

    Northern peatlands store a large organic carbon (C) pool that is highly exposed to future environmental changes with consequent risk of releasing enormous amounts of C. Biotic changes in plant community structure and species abundance might have an even stronger impact on soil organic C dynamics in peatlands than the direct effects of abiotic changes. Therefore, a sound understanding of the impact of vegetation dynamics on C cycling will help to better predict the response of peatlands to environmental changes. Here, we aimed to assess the role of plant functional types (PFTs) in affecting peat decomposition in relation to climate warming. To this aim, we selected two peatlands at different altitude (i.e. 1300 and 1700 m asl) on the south-eastern Alps of Italy. The two sites represent a contrast in temperature, overall vascular plant biomass and relative ericoids abundance, with the highest biomass and ericoids occurrence at the low latitude. Within the sites we selected 20 plots of similar microtopographical position and general vegetation type (hummocks). All plots contained both graminoids and ericoids and had a 100% cover of Sphagnum mosses. The plots were subjected to four treatments (control, and three clipping treatments) in which we selectively removed aboveground biomass of ericoids, graminoids or both to explore the contribution of the different PFTs for soil respiration (n=5) and peat chemistry. Peat chemical composition was determined by the analysis of C and N and their stable isotopes in association with pyrolysis GC/MS. Soil respiration was measured after clipping with a Licor system. Preliminary findings suggest that peat decomposition pathway and rate depend on plant species composition and particularly on differences in root activity between PFTs. Finally, this study underlines the importance of biotic drivers to predict the effects of future environmental changes on peatland C cycling.

  2. Rain events decrease boreal peatland net CO2 uptake through reduced light availability.

    PubMed

    Nijp, Jelmer J; Limpens, Juul; Metselaar, Klaas; Peichl, Matthias; Nilsson, Mats B; van der Zee, Sjoerd E A T M; Berendse, Frank

    2015-06-01

    Boreal peatlands store large amounts of carbon, reflecting their important role in the global carbon cycle. The short-term exchange and the long-term storage of atmospheric carbon dioxide (CO2 ) in these ecosystems are closely associated with the permanently wet surface conditions and are susceptible to drought. Especially, the single most important peat forming plant genus, Sphagnum, depends heavily on surface wetness for its primary production. Changes in rainfall patterns are expected to affect surface wetness, but how this transient rewetting affects net ecosystem exchange of CO2 (NEE) remains unknown. This study explores how the timing and characteristics of rain events during photosynthetic active periods, that is daytime, affect peatland NEE and whether rain event associated changes in environmental conditions modify this response (e.g. water table, radiation, vapour pressure deficit, temperature). We analysed an 11-year time series of half-hourly eddy covariance and meteorological measurements from Degerö Stormyr, a boreal peatland in northern Sweden. Our results show that daytime rain events systematically decreased the sink strength of peatlands for atmospheric CO2 . The decrease was best explained by rain associated reduction in light, rather than by rain characteristics or drought length. An average daytime growing season rain event reduced net ecosystem CO2 uptake by 0.23-0.54 gC m(-2) . On an annual basis, this reduction of net CO2 uptake corresponds to 24% of the annual net CO2 uptake (NEE) of the study site, equivalent to a 4.4% reduction of gross primary production (GPP) during the growing season. We conclude that reduced light availability associated with rain events is more important in explaining the NEE response to rain events than rain characteristics and changes in water availability. This suggests that peatland CO2 uptake is highly sensitive to changes in cloud cover formation and to altered rainfall regimes, a process hitherto largely

  3. Multi-decadal water-table manipulation alters peatland hydraulic structure and moisture retention.

    NASA Astrophysics Data System (ADS)

    Moore, Paul; Morris, Paul; Waddington, James

    2015-04-01

    Peatlands are a globally important store of freshwater and soil carbon. However, there is a concern that these water and carbon stores may be at risk due to climate change as vapour pressure deficits, evapotranspiration and summer moisture deficits are expected to increase, leading to greater water table (WT) drawdown in northern continental regions where peatlands are prevalent. We argue that in order to evaluate the hydrological response (i.e. changes in WT level, storage, surface moisture availability, and moss evaporation) of peatlands under future climate change scenarios, the hydrophysical properties of peat and disparities between microforms must be well understood. A peatland complex disturbed by berm construction in the 1950's was used to examine the long-term impact of WT manipulation on peatland hydraulic properties and moisture retention at three adjacent sites with increasing average depth to WT (WET, INTermediate reference, and DRY). All three sites exhibited a strong depth dependence for hydraulic conductivity, specific yield, and bulk density. Moreover, the effect of microform on near-surface peat properties tended to be greater than the site effect. Bulk density was found to explain a high amount of variance (r2 > 0.69) in moisture retention across a range of pore water pressures (-15 to -500 cm H2O), where bulk density tended to be higher in hollows. The estimated residual water content for surface Sphagnum samples, while on average lower in hummocks (0.082 m3 m-3) versus hollows (0.087 m3 m-3), increased from WET (0.058 m3 m-3) to INT (0.088 m3 m-3) to DRY (0.108 m3 m-3) which has important implications for moisture stress under conditions of persistent WT drawdown. While we did not observe significant differences between sites, we did observe a greater proportional coverage and greater relative height of hummocks at the drier sites. Given the potential importance of microtopographic succession for altering peatland hydraulic structure, our

  4. Multidisciplinary approach to identify aquifer-peatland connectivity

    NASA Astrophysics Data System (ADS)

    Larocque, Marie; Pellerin, Stéphanie; Cloutier, Vincent; Ferlatte, Miryane; Munger, Julie; Quillet, Anne; Paniconi, Claudio

    2015-04-01

    In southern Quebec (Canada), wetlands sustain increasing pressures from agriculture, urban development, and peat exploitation. To protect both groundwater and ecosystems, it is important to be able to identify how, where, and to what extent shallow aquifers and wetlands are connected. This study focuses on peatlands which are especially abundant in Quebec. The objective of this research was to better understand aquifer-peatland connectivity and to identify easily measured indicators of this connectivity. Geomorphology, hydrogeochemistry, and vegetation were selected as key indicators of connectivity. Twelve peatland transects were instrumented and monitored in the Abitibi (slope peatlands associated with eskers) and Centre-du-Quebec (depression peatlands) regions of Quebec (Canada). Geomorphology, geology, water levels, water chemistry, and vegetation species were identified/measured on all transects. Flow conditions were simulated numerically on two typical transects. Results show that a majority of peatland transects receives groundwater from a shallow aquifer. In slope peatlands, groundwater flows through the organic deposits towards the peatland center. In depression peatlands, groundwater flows only 100-200 m within the peatland before being redirected through surface routes towards the outlet. Flow modeling and sensitivity analysis have identified that the thickness and hydraulic conductivity of permeable deposits close to the peatland and beneath the organic deposits influence flow directions within the peatland. Geochemical data have confirmed the usefulness of total dissolved solids (TDS) exceeding 14 mg/L as an indicator of the presence of groundwater within the peatland. Vegetation surveys have allowed the identification of species and groups of species that occur mostly when groundwater is present, for instance Carex limosa and Sphagnum russowii. Geomorphological conditions (slope or depression peatland), TDS, and vegetation can be measured

  5. (Model) Peatlands in late Quaternary interglacials

    NASA Astrophysics Data System (ADS)

    Kleinen, Thomas; Brovkin, Victor

    2016-04-01

    Peatlands have accumulated a substantial amount of carbon, roughly 600 PgC, during the Holocene. Prior to the Holocene, there is relatively little direct evidence of peatlands, though coal deposits bear witness to a long history of peat-forming ecosystems going back to the Carboniferous. We therefore need to rely on models to investigate peatlands in times prior to the Holocene. We have developed a dynamical model of wetland extent and peat accumulation, integrated in the coupled climate carbon cycle model of intermediate complexity CLIMBER2-LPJ, in order to mechanistically model interglacial carbon cycle dynamics. This model consists of the climate model of intermediate complexity CLIMBER2 and the dynamic global vegetation model LPJ, which we have extended with modules to determine peatland extent and carbon accumulation. The model compares reasonably well to Holocene peat data. We have used this model to investigate the dynamics of atmospheric CO2 in the Holocene and two other late Quaternary interglacials, namely the Eemian, which is interesting due to its warmth, and Marine Isotope Stage 11 (MIS11), which is the longest interglacial during the last 500ka. We will also present model results of peatland extent and carbon accumulation for these interglacials. We will discuss model shortcomings and knowledge gaps currently preventing an application of the model to full glacial-interglacial cycles.

  6. Discoloration of polyvinyl chloride (PVC) tape as a proxy for water-table depth in peatlands: validation and assessment of seasonal variability

    USGS Publications Warehouse

    Booth, Robert K.; Hotchkiss, Sara C.; Wilcox, Douglas A.

    2005-01-01

    Summary: 1. Discoloration of polyvinyl chloride (PVC) tape has been used in peatland ecological and hydrological studies as an inexpensive way to monitor changes in water-table depth and reducing conditions. 2. We investigated the relationship between depth of PVC tape discoloration and measured water-table depth at monthly time steps during the growing season within nine kettle peatlands of northern Wisconsin. Our specific objectives were to: (1) determine if PVC discoloration is an accurate method of inferring water-table depth in Sphagnum-dominated kettle peatlands of the region; (2) assess seasonal variability in the accuracy of the method; and (3) determine if systematic differences in accuracy occurred among microhabitats, PVC tape colour and peatlands. 3. Our results indicated that PVC tape discoloration can be used to describe gradients of water-table depth in kettle peatlands. However, accuracy differed among the peatlands studied, and was systematically biased in early spring and late summer/autumn. Regardless of the month when the tape was installed, the highest elevations of PVC tape discoloration showed the strongest correlation with midsummer (around July) water-table depth and average water-table depth during the growing season. 4. The PVC tape discoloration method should be used cautiously when precise estimates are needed of seasonal changes in the water-table.

  7. The Structure and Function of Peatlands in the Hudson Bay Lowlands - Comparing a Pristine and a Hydrologically Impacted Peatland Site

    NASA Astrophysics Data System (ADS)

    Harris, L. I.; Roulet, N. T.; Moore, T. R.

    2014-12-01

    Climate change is considered to pose a significant risk to the vast and varied peatlands of the Hudson Bay Lowlands (HBL). Changes in peatland biogeochemical processes in this region could have major consequences for global greenhouse gas exchange and climate regulation, and yet there are still many gaps and uncertainties in our knowledge of these processes. In particular, our understanding of the mechanisms controlling the structure (vegetation and water table) and function (carbon flux) of these systems is limited. Various theories and models of peatland development have been proposed, including those that describe peatlands as self-regulating systems where long-term stability is maintained by feedback between biological and hydrological processes. There is limited field data however to support the different development theories and to validate proposed feedback mechanisms. Understanding how peatlands are controlled by internal and external forces is also particularly important when considering possible ecosystem shifts due to climate change. Here we compare data from a pristine peatland and a drained peatland site in the HBL to understand peatland structure and function in current climate conditions and a future climate scenario (drier conditions). We measured carbon dioxide and methane fluxes using closed chambers at 51 collar locations (12 collars at the hydrologically impacted site, 39 collars at the pristine peatland site - triplicates at both study sites) representing a total of 13 vegetation communities and different peatland microforms (hummocks, ridges, hollows and pools). Continuous hydrological measurements and vegetation surveys were also completed. These results suggest that peatland structure and function in the HBL must be explained by a combination of peatland development mechanisms and that these mechanisms are dependent on the variable hydroecological setting of peatland areas. We suggest that the drained peatland site may represent an

  8. Long-term macronutrient stoichiometry of UK ombrotrophic peatlands

    NASA Astrophysics Data System (ADS)

    Schillereff, Daniel; Boyle, John; Toberman, Hannah; Adams, Jessica; Tipping, Ed

    2016-04-01

    Ombrotrophic peatlands across northern latitudes represent a globally-important store for carbon (C), nitrogen (N) and phosphorus (P) through the Holocene. A key characteristic of ombrotrophic bogs is that N, P and other elements vital to their biogeochemical functioning are almost exclusively supplied by hydrological and biological inputs from the atmosphere. While different mechanisms regulating the atmospheric supply of N and P and their limiting effects on bog productivity have been widely studied, limited attention has been paid to the long-term patterns of, and controls on, macronutrient accumulation, cycling and stoichiometry in ombrotrophic peatlands. Indeed there is a dearth of C, N and P stoichiometric data from the UK despite decades of peatland research. Using data from 15 sites, we report the first estimates of millennial-scale macronutrient concentrations and accumulation rates in UK ombrotrophic peats. Carbon, nitrogen and phosphorus concentrations were measured on cores from five ombrotrophic blanket mires, spanning 4000-10000 years to present, and integrated with existing nutrient profiles from ten Scottish sites. Long-term C, N and P concentrations for the UK are 55.1, 1.55 and 0.037 wt%, similar to the few existing northern and tropical comparable sites worldwide. The uppermost peat (0 - 0.2 m) is more enriched in P and N (51.0, 1.86, and 0.070 wt%), while the deeper peat (0.5 - 1.25 m) is more depleted (56.6, 1.39, and 0.028 wt%). Long-term average (whole core) accumulation rates of carbon, nitrogen and phosphorus are 25.3±2.2 gC m‑2 yr‑1, 0.70±0.09 gN m‑2 yr‑1 and 0.018±0.004 gP m‑2 yr‑1, again similar to values reported elsewhere in the world. A number of significant findings can be drawn from our results: i) N and P concentrations in ombrotrophic peat are strongly associated, such that a regression model of N concentration on P concentration and mean annual precipitation, based on global meta data for surface peat samples, can

  9. Peatland Structural Controls on Spring Distribution

    NASA Astrophysics Data System (ADS)

    Hare, D. K.; Boutt, D. F.; Hackman, A. M.; Davenport, G.

    2013-12-01

    The species richness of wetland ecosystems' are sustained by the presence of discrete groundwater discharge, or springs. Springs provide thermal refugia and a source of fresh water inflow crucial for survival of many wetland species. The subsurface drivers that control the spatial distribution of surficial springs throughout peatland complexes are poorly understood due to the many challenges peatlands pose for hydrologic characterization, such as the internal heterogeneities, soft, dynamic substrate, and low gradient of peat drainage. This has previously made it difficult to collect spatial data required for restoration projects that seek to support spring obligate and thermally stressed species such as trout. Tidmarsh Farms is a 577-acre site in Southeastern Massachusetts where 100+ years of cranberry farming has significantly altered the original peatland hydrodynamics and ecology. Farming practices such as the regular application of sand, straightening of the main channel, and addition of drainage ditches has strongly degraded this peatland ecosystem. Our research has overlain non-invasive geophysical, thermal, and water isotopic data from the Tidmarsh Farms peatland to provide a detailed visualization of how subsurface peat structure and spring patterns correlate. Ground penetrating radar (GPR) has proven particularly useful in characterizing internal peat structure and the mineral soil interface beneath peatlands, we interpolate the peatland basin at a large scale (1 km2) and compare this 3-D surface to the locations of springs on the peat platform. Springs, expressed as cold anomalies in summer and warm anomalies in winter, were specifically located by combining fiber-optic and infrared thermal surveys, utilizing the numerous relic agricultural drainage ditches as a sampling advantage. Isotopic signatures of the spring locations are used to distinguish local and regional discharge, differences that can be explained in part by the peat basin structure

  10. First isolation and characterization of Lactococcus garvieae from Brazilian Nile tilapia, Oreochromis niloticus, (L.), and pintado, Pseudoplathystoma corruscans (Spix and Agassiz)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lactococcus garvieae infection in cultured Nile tilapia, Oreochromis niloticus, (Linnaeus) and pintado, Pseudoplathystoma corruscans, (Spix and Agassiz) from Brazil is reported. The commercial bacterial identification system, Biolog Microlog®, confirmed the identity of L. garvieae. Infectivity tri...

  11. Trace element content of northern Ontario peat

    SciTech Connect

    Glooschenko, W.A.; Capoblanco, J.A.

    1982-03-01

    Peat samples were collected at 0-20- and 20-40-cm depths from several peatland ecosystems located in northern Ontario, Canada. Analysis was made for the trace metals Zn, Pb, Cu, Cr, Cd, and Hg. Concentration values in general were in the low ppm range and did not significantly differ in terms of peatland type or depth except for Pb. This element was signficantly higher in surface peats in bogs and fens. Concentration of metals in peats found in the study were equivalent to those in US coals, suggesting caution during combustion in terms of potential atmospheric input of metals.

  12. Within-Site Variation at a Boreal Peatland Fertilization Study

    NASA Astrophysics Data System (ADS)

    Neal, E. M.; Bubier, J. L.; Moore, T.

    2001-05-01

    Due to the importance of northern peatlands as a sink for atmospheric CO2, there is concern over the possible effects of increased nutrient input in such ecosystems. Changes in CO2 fluxes caused by nutrient inputs may result in peatlands becoming a net source of atmospheric CO2 due to increased rates of decomposition. Alternatively, such fertilization of nutrient limited environments may enhance current conditions to maintain peatlands as a net sink of CO2 by increasing rates of photosynthesis or inhibiting decomposition. However, such effects may only become apparent after an extended period of increased nutrient loading. Net Ecosystem Exchange (NEE) of atmospheric CO2 was measured over the course of the growing season (May-August 2000) at Mer Bleue, a raised, ombrotrophic bog in Ontario, Canada using a LI-COR 6200 infrared gas analyzer and climate-controlled chambers. Dominant plant communities were composed of Sphagnum species and ericaceous shrubs. The site was treated every three weeks with varying levels of Nitrogen (N) and Phosphorous (P). Treatments were based on the ecosystem's ambient nutrient load of approximately 0.26 g N/m2/year of NH4 and 0.40 g N/m2/year of NO3 due to wet atmospheric deposition. Collars were grouped into triplicates according to treatment levels: distilled water, PK (no N), 5 times ambient N, 5 times ambient N plus PK, 10 times ambient N plus PK, and 20 times ambient N plus PK. NEE ranged from -4.88 to 5.12 μ mol CO2/m2 in the control collars and from -7.99 to 7.66 μ mol CO2/m2 in the nutrient addition collars. Preliminary data analysis indicates that although there has been a slight response from the nutrient additions, subtle differences in micro topography at the fertilization site (which creates slight variation in water table and temperature) have had a stronger initial effect on NEE. When collars are compared according to treatment triplicates, the effects of water table and temperature have the strongest effect on NEE. In

  13. Relationship between peatland hydrology and biogeochemistry

    NASA Astrophysics Data System (ADS)

    Roulet, N. T.

    2012-04-01

    The 'boreal forest' landscape is composed of upland forests, peatlands, some of which are treed, lakes, streams, and in North America, beaver ponds. Each of these landscapes present quite different biogeochemical environments due to differences in both abiotic and biotic processes and conditions. A significant amount of the carbon (C) in the boreal landscape is stored in peatlands, in part, due to the effect of the water storage on C cycling. The near saturated conditions affect the plants that can grow in peatlands and over the shorter term moisture variability controls the rate of C input to the peat. In the peat water limits the supply of electron donors and this has a profound effect on the C biogeochemistry. Near peat surface the moisture storage can be quite dynamic and mostly oxic conditions prevail, but redox conditions change significantly within a few tenth of a meter below the surface where water residence times increase orders of magnitude. This limits the supply of electron donors and other substrates that control the rate of C mineralization. Understanding the links among the moisture dynamics, the chemical thermodynamics of temporally variable saturated environments, and the quality of C is critical to determining the sensitivity of the C stored in peatlands to environmental change.

  14. Origin of the Herman-Norcross-Tintah sequence of Lake Agassiz beaches in Manitoba, Canada

    NASA Astrophysics Data System (ADS)

    McMillan, Kyle; Teller, James T.

    2012-05-01

    The giant glacial Lake Agassiz basin is fringed by many strandlines, which have long been used to trace the paleogeography of the former lake over its 5000 year history. The oldest and highest of these strandlines were placed into three groups by Warren Upham in the 1890 s - the Herman, Norcross, and Tintah - and form a staircase of small landforms. The formation of these old strandlines began as early as ~13.9 cal (12.0 14C) kyr BP and ended ~12.8 cal (10.8 14C) kyr BP, based on OSL dates and the history of lake level in the Agassiz basin. New mapping and augering of beach ridges in southern Manitoba, Canada, associated with the earliest phase of the lake, indicate that there are a series of up to 28 small discontinuous beach ridges that are generally only a few metres high and a few tens of metres wide. These beaches mainly consist of weakly defined beds of poorly sorted sediments; in many cases a central sandy diamicton unit lies stratigraphically between overlying beach sediments and clay diamicton (till) below. Spatially, ridges are separated by silty or sandy units or gravel lags; inter-beach lagoonal organics were not found. We discuss the possible origin of these Lake Agassiz beaches, concluding that they were deposited over a few centuries by episodic storm events, as lake level slowly declined. We base this conclusion on the nature of the sediments in the beach ridges and the regional geomorphology, as well theoretical considerations about sedimentation along a regressing shoreline of a large lake. Other origins are rejected, although some other factors may have contributed to formation of some of the beaches, such as temporary increases in sediment supply, variable rate of outlet erosion, and short increases in lake-level that reworked sediment upslope into ridges. Using the time frame of 13.9 to 12.8 cal kyr BP for the formation of the beaches, the average interval between formation of each beach is ~39 years.

  15. Holocene peatland initiation in the Greater Everglades

    NASA Astrophysics Data System (ADS)

    Dekker, Stefan; de Boer, Hugo; Dermody, Brian; Wagner-Cremer, Friederike; Wassen, Martin; Eppinga, Maarten

    2015-04-01

    The mechanisms involved in the initiation and development of the Greater Everglades peatland ecosystems in South Florida (USA) remain a topic of discussion. In this study, we present an overview of basal ages of peat deposits in South Florida, which shows two major episodes of peatland initiation between 7.0-4.5 kyr and 3.5-2.0 kyr. Our analysis of regional climate proxy datasets led to three alternative hypotheses that may explain the timing and duration of these two peatland initiation episodes: (1) decreased drainage due to relative sea level (RSL) rise during the Holocene (2) gradual increase in precipitation throughout the Holocene, and (3) a combination of increasing precipitation, rising RSL and oscillations in the climate system. We test whether these three hypotheses can explain the pattern of initiation and development of the Greater Everglades peatlands using models that simulate the non-linear processes involved in peat production and decomposition in combination with the local drainage conditions of Southern Florida. The model results suggest that RSL-rise alone cannot predict the onset of peat initiation in the Greater Everglades using our model setup. The model also implies that the climate was wet enough for peat development also during the early Holocene. The first two hypothesized mechanisms in combination with climate oscillations may explain the onset of peat accumulation at 8.2 kyr BP. The two-phased character of peat land initiation may be explained by the spatial distribution of local drainage conditions. As peatland development is highly non-linear, our model uncovers a mechanistic way how peats can suddenly shift from a dry high equilibrium to a wet low equilibrium resulting in lake formation as observed in paleo-ecological studies in the Greater Everglades.

  16. Individual rain events decrease long-term boreal peatland net CO2 uptake through reduced light availability

    NASA Astrophysics Data System (ADS)

    Nijp, Jelmer; Limpens, Juul; Metselaar, Klaas; Peichl, Matthias; Nilsson, Mats B.; van der Zee, Sjoerd; Berendse, Frank

    2016-04-01

    Northern peatlands sequester enormous quantities of carbon, suggesting these wetland ecosystems are of fundamental importance for the global carbon cycle. The long-term carbon storage of these wetland ecosystems depends on wet surface conditions, and is prone to drought. Future climate predictions indicate that most of the northern hemisphere is projected to become wetter, but that precipitation will fall in less frequent but more intense events. How such fine-scale climatic changes will affect long-term future net ecosystem exchange (NEE) of northern peatlands remains unknown. In this study we explored the short-term peatland NEE response to day time rain events during the growing season, how timing and characteristics of individual events and environmental conditions modify this response, and the impact of NEE responses to individual rain events for the longer-term (annual) carbon uptake. We used an 11-year time series of half-hourly eddy covariance and meteorological measurements from Degerö Stormyr, a peatland in northern Sweden. Our study shows daytime precipitation events systematically decreased the sink strength for atmospheric CO2. An individual daytime precipitation event reduced net ecosystem CO2 uptake by 0.23-0.54 gC m-2 on average. This reduction was best explained by the reduction in light associated with precipitation events, rather than by precipitation characteristics, timing of events, or drought length. On an annual basis, this reduction of net CO2 uptake corresponds to 24% of the annual net CO2 uptake (NEE) of the study site, equivalent to a 4.4% reduction of gross primary production (GPP) during the growing season. We conclude that accounting for the short-term response of NEE to individual rain events is crucial in determining climate change impacts on long-term sink strength of peatlands to atmospheric CO2. Moreover, reduced light availability associated with rain events is more important in explaining the NEE response to rain events than

  17. Seasonal changes in Sphagnum peatland testate amoeba communities along a hydrological gradient.

    PubMed

    Marcisz, Katarzyna; Lamentowicz, Lukasz; Słowińska, Sandra; Słowiński, Michał; Muszak, Witold; Lamentowicz, Mariusz

    2014-10-01

    Testate amoebae are an abundant and functionally important group of protists in peatlands, but little is known about the seasonal patterns of their communities. We investigated the relationships between testate amoeba diversity and community structure and water table depth and light conditions (shading vs. insolation) in a Sphagnum peatland in Northern Poland (Linje mire) in spring and summer 2010. We monitored the water table at five sites across the peatland and collected Sphagnum samples in lawn and hummock micro-sites around each piezometer, in spring (3 May) and mid-summer (6 August) 2010. Water table differed significantly between micro-sites and seasons (Kruskal-Wallis test, p=0.001). The community structure of testate amoebae differed significantly between spring and summer in both hummock and lawn micro-sites. We recorded a small, but significant drop in Shannon diversity, between spring and summer (1.76 vs. 1.72). Strongest correlations were found between testate amoeba communities and water table lowering and light conditions. The relative abundance of mixotrophic species Hyalosphenia papilio, Archerella flavum and of Euglypha ciliata was higher in the summer. PMID:25176338

  18. Long-term change in storm hydrographs in response to peatland vegetation change

    NASA Astrophysics Data System (ADS)

    Grayson, R.; Holden, J.; Rose, R.

    2010-08-01

    SummaryThe runoff from blanket peatland catchments tends to be dominated by flashy stormflows. However, it is not known whether changes in vegetation cover influence the nature of stormflow hydrographs from blanket peatlands. This is important since degraded peatlands are of concern to restoration bodies who seek to understand the wider impacts of restoration investment on ecosystem services. This paper tests the hypothesis that peak flows are significantly higher and lag times shorter at the catchment scale when blanket peat vegetation cover is reduced. Storm hydrograph data from the 1950s to the present day are analysed from a blanket peat catchment in northern England. The proportion of the catchment that was vegetated appears to have declined between the early 1950s and mid 1970s and then increased again to the present day. The changes in the proportion of bare peat over the catchment are coincident with changes in storm hydrographs. Hydrographs were significantly peakier with higher peaks per unit of rainfall (0.40 m 3 mm -1 compared with 0.27 m 3 mm -1) and narrower hydrograph shapes during the more eroded periods in the catchment and less so as the site has revegetated. Mean peak storm discharge was also significantly higher during the most eroded period. Thus, for the first time we have found evidence in a blanket peat headwater catchment that vegetation cover influences river flow response to rainfall.

  19. Reduced North Atlantic deep water coeval with the glacial Lake Agassiz freshwater outburst.

    PubMed

    Kleiven, Helga Kikki Flesche; Kissel, Catherine; Laj, Carlo; Ninnemann, Ulysses S; Richter, Thomas O; Cortijo, Elsa

    2008-01-01

    An outstanding climate anomaly 8200 years before the present (B.P.) in the North Atlantic is commonly postulated to be the result of weakened overturning circulation triggered by a freshwater outburst. New stable isotopic and sedimentological records from a northwest Atlantic sediment core reveal that the most prominent Holocene anomaly in bottom-water chemistry and flow speed in the deep limb of the Atlantic overturning circulation begins at approximately 8.38 thousand years B.P., coeval with the catastrophic drainage of Lake Agassiz. The influence of Lower North Atlantic Deep Water was strongly reduced at our site for approximately 100 years after the outburst, confirming the ocean's sensitivity to freshwater forcing. The similarities between the timing and duration of the pronounced deep circulation changes and regional climate anomalies support a causal link. PMID:18063758

  20. The name of the father: conflict between Louis and Alexander Agassiz and the Embiotoca surfperch radiation.

    PubMed

    Bernardi, G

    2009-04-01

    The surfperch genus Embiotoca currently comprises two species, Embiotoca jacksoni, the black surfperch, and Embiotoca lateralis, the striped surfperch. Originally, however, Louis Agassiz described a third species in the genus Embiotoca, the rainbow surfperch, Embiotoca caryi. This latter name was changed by Louis' son, Alexander, to Hypsurus caryi, a name that remains valid. In this study, new molecular data (3545 bp of DNA from four mitochondrial and two nuclear DNA regions) indicated that the rainbow surfperch should be retained within the genus Embiotoca, a result consistent with recent morphological data. Adaptive radiation combined with sexual selection resulting in rapid morphological changes in the rainbow surfperch may have contributed to the conflicting position of this species. PMID:20735618

  1. Integrating peatlands and permafrost into a dynamic global vegetation model: 1. Evaluation and sensitivity of physical land surface processes

    NASA Astrophysics Data System (ADS)

    Wania, R.; Ross, I.; Prentice, I. C.

    2009-09-01

    Northern peatlands and permafrost soils are associated with large carbon stocks. Rising temperatures are likely to affect the carbon balance in high-latitude ecosystems, but to what degree is uncertain. We have enhanced the Lund-Potsdam-Jena (LPJ) dynamic global vegetation model by introducing processes necessary to simulate permafrost dynamics, peatland hydrology, and peatland vegetation. The new version, LPJ-WHy v1.2, was used to study soil temperature, active layer depth, permafrost distribution, and water table position. Modeled soil temperatures agreed well with observations, apart from a Siberian site where the soil is insulated by an extensive shrub layer. Water table positions were generally in the range of observations, with some exceptions. Simulated active layer depth showed a mean absolute error of 44 cm when compared to observations, but the error was reduced to 25 cm when the soil type for seven sites was manually corrected to mirror local conditions. A sensitivity test, in which temperature and precipitation were varied independently, showed that soil temperatures and active layer depths increased more under higher temperatures when precipitation was increased at the same time. The sensitivity experiment suggested persisting wet conditions in peatlands even under temperature increases of up to 9°C as long as annual precipitation is allowed to increase with temperature to the extent indicated by climate model experiments.

  2. Spatial variability of tephra and carbon accumulation in a Holocene peatland

    NASA Astrophysics Data System (ADS)

    Watson, E. J.; Swindles, G. T.; Lawson, I. T.; Savov, I. P.

    2015-09-01

    Microscopic tephra layers ('cryptotephras') represent important age-equivalent stratigraphic markers utilised in many palaeoenvironmental reconstructions. When used in conjunction with proximal records of volcanic activity they can also provide information about volcanic ash cloud fallout and frequency. However, the spatial distributions of tephra layers can be discontinuous even within the same region. Understanding the deposition and post-depositional redistribution of tephra is vital if we are to use cryptotephras as records of ash cloud occurrence and chronostratigraphic markers. The discrete nature of tephra layers also allows for detailed study into processes of deposition and reworking which affect many palaeoenvironmental proxy records. We undertook a multi-core study in order to examine the historical tephrostratigraphy of a raised peatland in Northern Ireland. Three tephra layers originating from Iceland (Hekla 1947, Hekla 1845 and Hekla 1510) are present in 14 of the 15 cores analysed. This suggests that in areas not influenced by snowfall or anthropogenic disturbance at the time of tephra delivery, the presence or absence of a tephra layer is generally consistent across a peatland of this type. However, tephra shard counts (per unit area) vary by an order of magnitude between cores. These intra-site differences may confound the interpretation of shard counts from single cores as records of regional ash cloud mass/density. Bootstrap resampling analysis suggests that total shard counts from multiple cores are required in order to make a reliable estimate of median shard counts for a site. The presence of three historical tephras in 14 cores enables a spatio-temporal analysis of the long-term apparent rate of carbon accumulation (LARCA) in the peatland. Substantial spatial and temporal variations in LARCA are identified over the last ∼450 years. This high variability needs to be taken into account when designing studies of peatland carbon accumulation.

  3. Vegetation exerts a greater control on litter decomposition than climate warming in peatlands.

    PubMed

    Ward, Susan E; Orwin, Kate H; Ostle, Nicholas J; Briones, J I; Thomson, Bruce C; Griffiths, Robert I; Oakley, Simon; Quirk, Helen; Bardget, Richard D

    2015-01-01

    Historically, slow decomposition rates have resulted in the accumulation of large amounts of carbon in northern peatlands. Both climate warming and vegetation change can alter rates of decomposition, and hence affect rates of atmospheric CO2 exchange, with consequences for climate change feedbacks. Although warming and vegetation change are happening concurrently, little is known about their relative and interactive effects on decomposition processes. To test the effects of warming and vegetation change on decomposition rates, we placed litter of three dominant species (Calluna vulgaris, Eriophorum vaginatum, Hypnum jutlandicum) into a peatland field experiment that combined warming.with plant functional group removals, and measured mass loss over two years. To identify potential mechanisms behind effects, we also measured nutrient cycling and soil biota. We found that plant functional group removals exerted a stronger control over short-term litter decomposition than did approximately 1 degrees C warming, and that the plant removal effect depended on litter species identity. Specifically, rates of litter decomposition were faster when shrubs were removed from the plant community, and these effects were strongest for graminoid and bryophyte litter. Plant functional group removals also had strong effects on soil biota and nutrient cycling associated with decomposition, whereby shrub removal had cascading effects on soil fungal community composition, increased enchytraeid abundance, and increased rates of N mineralization. Our findings demonstrate that, in addition to litter quality, changes in vegetation composition play a significant role in regulating short-term litter decomposition and belowground communities in peatland, and that these impacts can be greater than moderate warming effects. Our findings, albeit from a relatively short-term study, highlight the need to consider both vegetation change and its impacts below ground alongside climatic effects when

  4. Quantification of peatland specific yield: toward a general peatland water storage indicator

    NASA Astrophysics Data System (ADS)

    Bourgault, Marc-André; Larocque, Marie; Garneau, Michelle

    2016-04-01

    Peatlands are water saturated environment that can be connected to rivers and aquifers. This connectivity is in part controlled by peat properties such as hydraulic conductivity (K) and specific yield (SY). For the last twenty years, many studies have quantified these parameters in peatlands, contributing to better understand peatland hydrological functions such as water storage, river base flows, and groundwater recharge. Nonetheless, the understanding of peatland water storage capacity is still very limited both at local and global scale, in part due to the lack of unique and simple method to quantify the spatial variations of these properties. The objective of this project is to 1) develop a new in situ method to quantify vertical specific yield variations and 2) evaluate the use of this method to quantify storage capacity of peatland. Using an approach based on the water table fluctuation (WTF) method, a program was developed in R to quantify vertical variation of SY with depth for the hydrologically active layer of five southern ombrotrophic peatland complexes of the St. Lawrence Lowlands (southern Quebec, Canada). In each peatland, three water table wells (2 cm diameter and 1 m deep) were installed upgradient, mi-gradient, and downgradient. The wells were instrumented to measure water levels every 5 minutes during summer 2014 and 2015. The range of mean annual water table depths varies from 9.4 to 49.3 cm below the peat surface. Near each piezometer, a 1 m long peat core was sampled using a box corer. Each core was divided into 7 x 7 x 7 cm3 peat cubes and analysed using gravitational drainage experiments. In one of the peatland complexes, a 25 x 60 x 40 cm3 peat sample was collected in the upgradient location. Using a tension table, specific storage was measured on this peat sample at 1.0 cm intervals between 0-20 cm and 2.5 cm intervals between 20-36 cm. The WTF method and the gravitational drainage experiments show similar results, confirming the validity

  5. In situ sulphate stimulation of mercury methylation in a boreal peatland: Toward a link between acid rain and methylmercury contamination in remote environments

    NASA Astrophysics Data System (ADS)

    Branfireun, Brian A.; Roulet, Nigel T.; Kelly, Carol. A.; Rudd, John W. M.

    1999-09-01

    Recent studies have found that "pristine" peatlands have high peat and pore water methylmercury (MeHg) concentrations and that peatlands may act as large sources of MeHg to the downstream aquatic system, depending upon the degree of hydrologie connectivity and catchment physiography. Sulphate-reducing bacteria have been implicated as principal methylators of inorganic mercury in many environments with previous research focused primarily on mercury methylation in aquatic sediments. Experiments in a poor fen in the Experimental Lakes Area, northwestern Ontario, Canada, demonstrated that the in situ addition of sulphate to peat and peat pore water resulted in a significant increase in pore water MeHg concentrations. As peatlands cover a large area of the Northern Hemisphere, this finding has potentially far ranging implications for the global mercury cycle, particularly in areas impacted by anthropogenically derived sulphate where the methylmercury fraction of total mercury species may be much larger than in nonimpacted environments.

  6. Nest guarding by female Agassiz's desert tortoise (Gopherus agassizii) at a wind-energy facility near Palm Springs, California

    USGS Publications Warehouse

    Agha, Mickey; Lovich, Jeffrey E.; Ennen, Joshua R.; Wilcox, Ethan

    2013-01-01

    We observed behavior consistent with nest-guarding in Agassiz's desert tortoise (Gopherus agassizii) at two nests in a large wind-energy-generation facility near Palm Springs, California, locally known as the Mesa Wind Farm. As researchers approached the nests, female desert tortoises moved to the entrance of their burrows and positioned themselves sideways, directly over their nests. One female stretched her limbs outward and wedged herself into the burrow (her plastron directly above the nest). Guarding of nests is rarely observed in Agassiz's desert tortoise but can occur as a result of attempted predation on eggs by Gila monsters (Heloderma suspectum) or in direct response to the perceived threat posed by researchers. This is the first report of nest-guarding for G. agassizii in the Sonoran Desert ecosystem of California.

  7. The occultation of Epsilon Gem by Mars as observed from Agassiz Station. [for atmosphere temperature profile investigation

    NASA Technical Reports Server (NTRS)

    Liller, W.; Papaliolios, C.; French, R. G.; Elliot, J. L.; Church, C.

    1978-01-01

    Observations of the April 8, 1976, occultation of Epsilon Gem by Mars made at the Agassiz Station of the Harvard College Observatory have been analyzed to yield temperature profiles of the Martian atmosphere for number densities between 10 to the 13th and 10 to the 15th power per cu cm. Pronounced wavelike structure is evident in both immersion and emersion profiles, with a peak-to-peak variation of up to 50 K and a vertical scale of 20 km.

  8. Preliminary Cosmogenic Surface Exposure Ages on Laurentide Ice-sheet Retreat and Opening of the Eastern Lake Agassiz Outlets

    NASA Astrophysics Data System (ADS)

    Leydet, D.; Carlson, A. E.; Sinclair, G.; Teller, J. T.; Breckenridge, A. J.; Caffee, M. W.; Barth, A. M.

    2015-12-01

    The chronology for the eastern outlets of glacial Lake Agassiz holds important consequences for the cause of Younger Dryas cold event during the last deglaciation. Eastward routing of Lake Agassiz runoff was originally hypothesized to have triggered the Younger Dryas. However, currently the chronology of the eastern outlets is only constrained by minimum-limiting radiocarbon ages that could suggest the eastern outlets were still ice covered at the start of the Younger Dryas at ~12.9 ka BP, requiring a different forcing of this abrupt climate event. Nevertheless, the oldest radiocarbon ages are still consistent with an ice-free eastern outlet at the start of the Younger Dryas. Here we will present preliminary 10-Be cosmogenic surface exposure ages from the North Lake, Flat Rock Lake, glacial Lake Kaministiquia, and Lake Nipigon outlets located near Thunder Bay, Ontario. These ages will date the timing of the deglaciation of the Laurentide ice sheet in the eastern outlet region of glacial Lake Agassiz. This will provide an important constraint for the hypothesized freshwater forcing of the cause of Younger Dryas cold event.

  9. Greenhouse gas flux from tropical peatlands: context and controls

    NASA Astrophysics Data System (ADS)

    Page, Susan; Jauhiainen, Jyrki; Hooijer, Aljosja

    2010-05-01

    Peatlands play a key role within the global carbon cycle by storing a disproportionately large amount of soil carbon relative to other terrestrial ecosystems. Peatland systems have accumulated carbon through an imbalance between the uptake and release of CO2 from and to the atmosphere. In a pristine condition, tropical peat swamp forest is one of the world's most efficient carbon sequestering ecosystems as a result of substantial biomass production and the waterlogged condition of the peat, which reduces significantly the rate of organic matter decomposition. Tropical peat deposits have acted as sinks of atmospheric carbon since at least the beginning of the Holocene and, in some cases, the Late Pleistocene. They currently store ~ 65 Gt C, most of which is located in thick deposits in Southeast Asia. Tropical peatlands are, however, vulnerable to destabilisation through both human and climate induced changes. The former include poor forest and land management practices, drainage, large-scale conversion to plantation agriculture, and fire; these lead to degradation and reduction of the peatland carbon store and contribute to greenhouse gas emissions, whilst compromising other valuable ecosystem services. Climate induced changes include susceptibility to drought-impacts, particularly during ENSO-events; there are also initial indications that regional climates in areas with extensive peatlands are experiencing reduced rainfall, which threatens longer term peatland sustainability. This paper reviews the current understanding of carbon-climate-human interactions on tropical peatlands. It focuses on the main causes of peatland degradation, in particular natural and anthropogenic changes in peatland hydrology; considers the risks that hydrological change, especially water-table drawdown, poses to the peatland carbon pool; and assesses the scale of peatland drainage-associated CO2 emissions, which are currently of the order of ~250 Mt C yr-1 for Southeast Asian peatlands

  10. Modeling water table dynamics in managed and restored peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, Fabio; Rasche, Livia; Hermans, Renée; Subke, Jens-Arne; Schneider, Uwe; Brovkin, Victor

    2016-04-01

    European peatlands have been extensively managed over past centuries. Typical management activities consisted of drainage and afforestation, which lead to considerable damage to the peat and potentially significant carbon loss. Recent efforts to restore previously managed peatlands have been carried out throughout Europe. These restoration efforts have direct implications for water table depth and greenhouse gas emissions, thus impacting on the ecosystem services provided by peatland areas. In order to quantify the impact of peatland restoration on water table depth and greenhouse gas budget, We coupled the Environmental Policy Integrated Climate (EPIC) model to a process-based model for methane emissions (Walter and Heimann, 2000). The new model (EPIC-M) can potentially be applied at the European and even at the global scale, but it is yet to be tested and evaluated. We present results of this new tool from different peatlands in the Flow Country, Scotland. Large parts of the peatlands of the region have been drained and afforested during the 1980s, but since the late 1990s, programs to restore peatlands in the Flow Country have been enforced. This region offers therefore a range of peatlands, from near pristine, to afforested and drained, with different resoration ages in between, where we can apply the EPIC-M model and validate it against experimental data from all land stages of restoration Goals of this study are to evaluate the EPIC-M model and its performances against in situ measurements of methane emissions and water table changes in drained peatlands and in restored ones. Secondly, our purpose is to study the environmental impact of peatland restoration, including methane emissions, due to the rewetting of drained surfaces. To do so, we forced the EPIC-M model with local meteorological and soil data, and simulated soil temperatures, water table dynamics, and greenhouse gas emissions. This is the first step towards a European-wide application of the EPIC

  11. Modelling methane fluxes from managed and restored peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, F.; Rasche, L.; Hermans, R.; Subke, J. A.; Schneider, U. A.; Brovkin, V.

    2015-12-01

    European peatlands have been extensively managed over past centuries. Typical management activities consisted of drainage and afforestation, which lead to considerable damage to the peat and potentially significant carbon loss. Recent efforts to restore previously managed peatlands have been carried out throughout Europe. These restoration efforts have direct implications for water table depth and greenhouse gas emissions, thus impacting on the ecosystem services provided by peatland areas. In order to quantify the impact of peatland restoration on water table depth and greenhouse gas budget, We coupled the Environmental Policy Integrated Climate (EPIC) model to a process-based model for methane emissions (Walter and Heimann, 2000). The new model (EPIC-M) can potentially be applied at the European and even at the global scale, but it is yet to be tested and evaluated. We present results of this new tool from different peatlands in the Flow Country, Scotland. Large parts of the peatlands of the region have been drained and afforested during the 1980s, but since the late 1990s, programs to restore peatlands in the Flow Country have been enforced. This region offers therefore a range of peatlands, from near pristine, to afforested and drained, with different resoration ages in between, where we can apply the EPIC-M model and validate it against experimental data from all land stages of restoration. Goals of this study are to evaluate the EPIC-M model and its performances against in situ measurements of methane emissions and water table changes in drained peatlands and in restored ones. Secondly, our purpose is to study the environmental impact of peatland restoration, including methane emissions, due to the rewetting of drained surfaces. To do so, we forced the EPIC-M model with local meteorological and soil data, and simulated soil temperatures, water table dynamics, and greenhouse gas emissions. This is the first step towards a European-wide application of the EPIC

  12. Upscaling methane emission hotspots in boreal peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, Fabio; Runkle, Benjamin R. K.; Bruecher, Tim; Kleinen, Thomas; Brovkin, Victor

    2016-04-01

    Small-scale surface heterogeneities can influence land-atmosphere fluxes and therefore carbon, water and energy budgets on a larger scale. This effect is of particular relevance for high-latitude ecosystems, because of the great amount of carbon stored in their soils. Upscaling such small-scale surface heterogeneities and their effects to larger scales is a challenging issue in land surface modeling. We developed a novel approach to upscale local methane emissions in a boreal peatland from the micro-topographic scale to the landscape-scale. We based this parameterization on the analysis of the water table pattern generated by the Hummock-Hollow model (Cresto Aleina et al., 2015), a micro-topography resolving model for peatland hydrology and methane emissions. By computing the water table at the micro-topographic scale, the Hummock-Hollow model is able to describe the effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. We introduce the new parameterization of methane hotspots in a global model-like version of the Hummock-Hollow model. This latter version underestimates methane emissions because of the lack of representation of micro-topographic controls on peatland hydrology. We tested the robustness of the parameterization by simulating methane emissions for the present day and for the next century, forcing the model with three different RCP scenarios. The Hotspot parameterization, despite being calibrated for the 1976-2005 climatology, mimics the output of the micro-topography resolving model for all the simulated scenarios. The new approach bridges the scale gap of methane emissions between this version of the model and the configuration explicitly resolving micro-topography.

  13. Improving peatland erosion rate measurements through the use of terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Grayson, R.; Holden, J.; Jones, R.; Lloyd, A.

    2013-12-01

    Globally peatlands account for 30-50% of all carbon stored within soils (Holden, 2005). Within the UK they represent the single largest terrestrial carbon store, with blanket bogs covering roughly 7.5% (Tallis et al., 1997); unfortunately these upland blanket bogs are often found in a degraded state. The amount of carbon being lost to erosional processes in peatlands is poorly constrained, with estimates typically being based on traditional low-tech methods. Erosion pins have been the primary method for measuring erosion rates in peatlands; however their use is prone to error due to the depth of peat and its high water content which allows both horizontal and vertical movement through time. Erosion pins can only realistically be used over a relatively small area and assume erosion remains constant between pins making any upscaling problematic. Therefore, innovative methods are required to improve estimates of peatland erosion that are capable of increasing both spatial coverage and accuracy. Terrestrial laser scanning is increasingly being used by geomorphologists to produce highly detailed 3D topographic maps. A pilot study was undertaken to assess the ability of terrestrial laser scanning to measure erosion rates within peatlands and to identify any obstacles that may need to be overcome. An actively eroding blanket bog in northern England was chosen as the test site with surveys being carried out before and after winter as active erosion is most likely during winter months. Erosion measurements were also made using erosion pins to allow comparisons between the two methods. Terrestrial laser scanning was not only found to offer vastly improved spatial coverage compared with erosion pins but was also able to provide data at a much higher resolution. Erosion rates calculated using erosion pins were significantly higher than the average rate calculated using terrestrial laser scanning (-35mm compared to +2.5mm), this overestimation by the erosion pins primarily

  14. Drainage in Shallow Peatlands of Marginal Upland Landscapes: DOC Losses from High Flow Events

    NASA Astrophysics Data System (ADS)

    Grand-Clement, E.; Anderson, K.; Luscombe, D.; Gatis, N.; Benaud, P.; Brazier, R.

    2013-12-01

    Peatlands are widely represented in northern Europe, especially in the UK. In the South West of England (i.e. Exmoor, Dartmoor and Bodmin moors), climate change puts their existence under threat: according to recent modelling work, marginal peatlands are highly vulnerable to future temperature and precipitation change and are likely to be the first to disappear from as early as 2050. Additionally, peat cutting and intensive drainage for agricultural reclamation in the 19th and 20th century, have modified the hydrological behaviour of these shallow peatlands and dried out the upper layers, causing oxidation, erosion and vegetation change. Such anthropogenic interventions directly impact on the storage of carbon, but also the provision of other ecosystem services, such as the supply of drinking water, and the support of specific and rare habitats. Large restoration programs involving the blocking of drainage ditches are currently under way throughout the UK but, to date, little is known about the consequences of such management approaches on overall Carbon stocks, and whether the restoration can revert ecosystems back to a state similar to that of undisturbed peatlands. In this context, Exmoor is particularly vulnerable due to its location at the southernmost margin of the UK peatlands' geographical extent, and its dense network of drainage ditches putting pressure on already very shallow peat resources. We hypothesise that monitoring of these peatlands may provide an ';early warning system' for climatic impacts that could affect more northerly sites in years to come, as climates change more significantly. The aim of this study is to look at the current impact of peatland degradation on water quality on Exmoor during rainfall-runoff events. Our experimental approach employs detailed, high resolution monitoring of selected ditches that are representative of damaged conditions on Exmoor, from small- (30 x 30cm ditches) through medium- (50x50cm), large- (1-2m ditches

  15. Response of peatland ecosystem to climatic changes in Central-Eastern Europe: a long-term ecological approach

    NASA Astrophysics Data System (ADS)

    Slowinska, S.; Marcisz, K.; Slowinski, M. M.; Lamentowicz, M.; Lamentowicz, L.; Mitchell, E. A.

    2013-12-01

    Northern peatlands play a major role in the global carbon cycle, and they are valuable archives of the past environmental change. The functioning of these ecosystems depends on the feedback between biotic and abiotic factors that are still not fully understood. In our study we investigated relationships between hydrological (groundwater level fluctuations, hydrochemistry), meteorological conditions near the ground (air temperature and humidity, photosynthetically active radiation, leaf wetness, temperature and moisture of Sphagnum) and biological factors: vegetation patterns, Sphagnum mosses growth and testate amoebae (Protists) composition. We designed a long-term ecological study site in a Sphagnum mire in Northern Poland that consisted of five meteorological micro stations and eleven piezometers located in two transects at 5,95 ha area. During the growing season 2012 we observed significant differences between plots in terms of micrometeorological and hydrological conditions that resulted in different Sphagnum increments and seasonal dynamics of testate amoebae communities. Our study is very important to better understand how temperate peatlands react to the climatic change and recent warming. Obtained results revealed a high sensitivity of bog ecosystem to e.g. short-term heat waves. Further research will be conducted to model a potential response of Sphagnum peatland to the future climate change. Project supported by Polish National Science Centre grant No. NN306060940 and the grant PSPB-013/2010 from Switzerland through the Swiss Contribution to the enlarged European Union.

  16. Nutrient Controls on Methane Emissions in a Permafrost Thaw Subarctic Peatland

    NASA Astrophysics Data System (ADS)

    Kashi, N. N.; Perryman, C. R.; Malhotra, A.; Marek, E. A.; Giesler, R.; Varner, R. K.

    2015-12-01

    Permafrost peatlands in northern latitudes are large reservoirs of sequestered carbon that are vulnerable to climate change. While peatlands account for a small fraction of total global land surfaces, their potential to release sequestered carbon in response to higher temperatures is of concern. Of particular relevance is the conversion of these carbon stores into methane (CH4), a strong greenhouse gas with a global warming potential 20 times greater than that of CO2 over a 100-year time frame. Here, we explore how key nutrients impact the consumption of CH4 at the Stordalen Mire in Abisko, Sweden, a discontinuous permafrost peatland with expanding thaw over the last century. Peatland CH4 emissions are highly spatially variable due to multiple emission pathways and strong dependence on several environmental factors. Among controls on CH4 emissions, such as temperature and water table depth, primary production of wetland vegetation is also a strong factor in the variability of CH4 emissions. Plant community shifts among permafrost thaw stages subsequently change nutrient cycling and availability, which in turn impacts primary production. Early stages of permafrost thaw are mosaicked with a variety of vascular plants and mosses. We analyzed potential enzymatic activities of chitinase, glucosidase, and phosphatase as proxies for organic nitrogen, carbon, and phosphorus cycling, respectively, in tandem with potential CH4 oxidation rates. In addition, stoichiometric ratios of carbon, nitrogen, and phosphorus concentrations are used to illustrate nutrient limitation controls on CH4 oxidation rates. While CH4 emissions are low throughout initial thaw stages, < 7 CH4 mg m-2 day-1, we found they had the highest rates of potential CH4 oxidation. These permafrost thaw-induced CH4 oxidation rates are 5 and 11 times higher, in the surface and depth of the peat profile respectively, than subsequent aerobic permafrost thaw stages. As CH4 emissions are low in intact permafrost

  17. Do oxygen stable isotopes track precipitation moisture source in vascular plant dominated peatlands?

    NASA Astrophysics Data System (ADS)

    Charman, D.; Amesbury, M. J.; Newnham, R.; Loader, N.; Goodrich, J. P.; Gallego-Sala, A. V.; Royles, J.; Keller, E. D.; Baisden, W. T.

    2014-12-01

    Variations in the isotopic composition of precipitation are determined by fractionation processes which occur during temperature and humidity dependent phase changes associated with evaporation and condensation. Oxygen stable isotope ratios have therefore been frequently used as a source of palaeoclimate data from a variety of proxy archives. Exploitation of this record from ombrotrophic peatlands, where the source water used in cellulose synthesis is derived solely from precipitation, has been mostly limited to Northern Hemisphere Sphagnum-dominated bogs, with limited application in the Southern Hemisphere (SH) or in peatlands dominated by vascular plants. Throughout New Zealand (NZ), the preserved root matrix of the restionaceous wire rush (Empodisma spp.) forms deep peat deposits. NZ provides an ideal location to undertake empirical research into oxygen isotope fractionation in vascular peatlands because sites are ideally suited to single taxon analysis, preserve potentially high resolution full Holocene palaeoclimate records and are situated in the climatically sensitive SH mid-latitudes. Crucially, large gradients exist in the mean isotopic composition of precipitation across NZ, caused primarily by the relative influence of different climate modes. We test the capacity for δ18O analysis of Empodisma alpha cellulose from ombrotrophic restiad peatlands in NZ to provide a methodology for developing palaeoclimate records. We took surface plant, water and precipitation samples over spatial (six sites spanning >10° latitude) and temporal (monthly measurements over one year) gradients. We found a strong link between the isotopic compositions of surface root water, the most likely source water for plant growth, and precipitation in both datasets. Back-trajectory modelling of precipitation moisture source for rain days prior to sampling showed clear seasonality in the temporal data that was reflected in surface root water. The link between source water and plant

  18. Impact of hydrological variations on modeling of peatland CO2 fluxes: Results from the North American Carbon Program site synthesis

    NASA Astrophysics Data System (ADS)

    Sulman, Benjamin N.; Desai, Ankur R.; Schroeder, Nicole M.; Ricciuto, Dan; Barr, Alan; Richardson, Andrew D.; Flanagan, Lawrence B.; Lafleur, Peter M.; Tian, Hanqin; Chen, Guangsheng; Grant, Robert F.; Poulter, Benjamin; Verbeeck, Hans; Ciais, Philippe; Ringeval, Bruno; Baker, Ian T.; Schaefer, Kevin; Luo, Yiqi; Weng, Ensheng

    2012-03-01

    Northern peatlands are likely to be important in future carbon cycle-climate feedbacks due to their large carbon pools and vulnerability to hydrological change. Use of non-peatland-specific models could lead to bias in modeling studies of peatland-rich regions. Here, seven ecosystem models were used to simulate CO2fluxes at three wetland sites in Canada and the northern United States, including two nutrient-rich fens and one nutrient-poor,sphagnum-dominated bog, over periods between 1999 and 2007. Models consistently overestimated mean annual gross ecosystem production (GEP) and ecosystem respiration (ER) at all three sites. Monthly flux residuals (simulated - observed) were correlated with measured water table for GEP and ER at the two fen sites, but were not consistently correlated with water table at the bog site. Models that inhibited soil respiration under saturated conditions had less mean bias than models that did not. Modeled diurnal cycles agreed well with eddy covariance measurements at fen sites, but overestimated fluxes at the bog site. Eddy covariance GEP and ER at fens were higher during dry periods than during wet periods, while models predicted either the opposite relationship or no significant difference. At the bog site, eddy covariance GEP did not depend on water table, while simulated GEP was higher during wet periods. Carbon cycle modeling in peatland-rich regions could be improved by incorporating wetland-specific hydrology and by inhibiting GEP and ER under saturated conditions. Bogs and fens likely require distinct plant and soil parameterizations in ecosystem models due to differences in nutrients, peat properties, and plant communities.

  19. The subglacial origin of the Lake Agassiz-Ojibway final outburst flood

    NASA Astrophysics Data System (ADS)

    Lajeunesse, Patrick; St-Onge, Guillaume

    2008-03-01

    Deglaciation of North America resulted in the development of the ice-dammed lake Agassiz-Ojibway along the southern margin of the Laurentide Ice Sheet and its catastrophic northward drainage ~8.47kyr ago. This sudden outburst of fresh water may have weakened the Atlantic ocean overturning circulation and triggered the cold event that occurred 8.2kyr ago. Geological evidence of this flood has been documented in a red sedimentary bed in cores collected in Hudson Strait and by submarine features in Hudson Bay. However, there have been few constraints on the manner in which the lake drained: for example, by flow over the ice sheet or beneath it, in one or several pulses and where the flood routes were located. Here we present seafloor images obtained using multibeam sonar, which reveal that the outburst flood displaced icebergs to produce arcuate (arc-shaped) scours on the seafloor with a dominant east-northeast-west-southwest orientation. The flood also produced sandwaves in areas unaffected by the arcuate scours, indicating they were protected from iceberg scouring by overlying ice during the event. We suggest that these sandwaves, along with submarine channels inferred from the data, indicate that Laurentide ice was lifted buoyantly, enabling the flood to traverse southern Hudson Bay under the ice sheet.

  20. Serologic and molecular evidence for Testudinid herpesvirus 2 infection in wild Agassiz's desert tortoises, Gopherus agassizii.

    PubMed

    Jacobson, Elliott R; Berry, Kristin H; Wellehan, James F X; Origgi, Francesco; Childress, April L; Braun, Josephine; Schrenzel, Mark; Yee, Julie; Rideout, Bruce

    2012-07-01

    Following field observations of wild Agassiz's desert tortoises (Gopherus agassizii) with oral lesions similar to those seen in captive tortoises with herpesvirus infection, we measured the prevalence of antibodies to Testudinid herpesvirus (TeHV) 3 in wild populations of desert tortoises in California. The survey revealed 30.9% antibody prevalence. In 2009 and 2010, two wild adult male desert tortoises, with gross lesions consistent with trauma and puncture wounds, respectively, were necropsied. Tortoise 1 was from the central Mojave Desert and tortoise 2 was from the northeastern Mojave Desert. We extracted DNA from the tongue of tortoise 1 and from the tongue and nasal mucosa of tortoise 2. Sequencing of polymerase chain reaction products of the herpesviral DNA-dependent DNA polymerase gene and the UL39 gene respectively showed 100% nucleotide identity with TeHV2, which was previously detected in an ill captive desert tortoise in California. Although several cases of herpesvirus infection have been described in captive desert tortoises, our findings represent the first conclusive molecular evidence of TeHV2 infection in wild desert tortoises. The serologic findings support cross-reactivity between TeHV2 and TeHV3. Further studies to determine the ecology, prevalence, and clinical significance of this virus in tortoise populations are needed. PMID:22740541

  1. Translocation as a conservation tool for Agassiz's desert tortoises: survivorship, reproduction, and movements

    USGS Publications Warehouse

    Nussear, K.E.; Tracy, C.R.; Medica, P.A.; Wilson, D.S.; Marlow, R.W.; Corn, P.S.

    2012-01-01

    We translocated 120 Agassiz's desert tortoises to 5 sites in Nevada and Utah to evaluate the effects of translocation on tortoise survivorship, reproduction, and habitat use. Translocation sites included several elevations, and extended to sites with vegetation assemblages not typically associated with desert tortoises in order to explore the possibility of moving animals to upper elevation areas. We measured survivorship, reproduction, and movements of translocated and resident animals at each site. Survivorship was not significantly different between translocated and resident animals within and among sites, and survivorship was greater overall during non-drought years. The number of eggs produced by tortoises was similar for translocated and resident females, but differed among sites. Animals translocated to atypical habitat generally moved until they reached vegetation communities more typical of desert tortoise habitat. Even within typical tortoise habitat, tortoises tended to move greater distances in the first year after translocation than did residents, but their movements in the second or third year after translocation were indistinguishable from those of resident tortoises. Our data show that tortoises translocated into typical Mojave desert scrub habitats perform well; however, the large first-year movements of translocated tortoises have important management implications. Projects that employ translocations must consider how much area will be needed to contain translocated tortoises and whether roads need fencing to prevent the loss of animals.

  2. Simulation of the cold climate event 8200 years ago by meltwater outburst from Lake Agassiz

    NASA Astrophysics Data System (ADS)

    Bauer, E.; Ganopolski, A.; Montoya, M.

    2004-09-01

    The cold climate anomaly about 8200 years ago is investigated with CLIMBER-2, a coupled atmosphere-ocean-biosphere model of intermediate complexity. This climate model simulates a cooling of about 3.6 K over the North Atlantic induced by a meltwater pulse from Lake Agassiz routed through the Hudson strait. The meltwater pulse is assumed to have a volume of 1.6 × 1014 m3 and a period of discharge of 2 years on the basis of glaciological modeling of the decay of the Laurentide Ice Sheet (LIS). We present a possible mechanism which can explain the centennial duration of the 8.2 ka cold event. The mechanism is related to the existence of an additional equilibrium climate state with reduced North Atlantic Deep Water (NADW) formation and a southward shift of the NADW formation area. Hints at the additional climate state were obtained from the largely varying duration of the pulse-induced cold episode in response to overlaid random freshwater fluctuations in Monte Carlo simulations. The model equilibrium state was attained by releasing a weak multicentury freshwater flux through the St. Lawrence pathway completed by the meltwater pulse. The existence of such a climate mode appears essential for reproducing climate anomalies in close agreement with paleoclimatic reconstructions of the 8.2 ka event. The results furthermore suggest that the temporal evolution of the cold event was partly a matter of chance.

  3. Reducing uncertainty in methane emission estimates from permafrost peatlands

    NASA Astrophysics Data System (ADS)

    Christensen, Torben R.

    2016-04-01

    Reducing uncertainty in methane emission estimates from permafrost peatlands Torben R. Christensen1,2 and coworkers 1) Department of Physical Geography and Ecosystem Science, Lund University, Sweden 2) Arctic Research Centre, Aarhus University, Denmark Depending on factors including temperature, snow duration and soil moisture conditions, emissions of the greenhouse gas methane from permafrost peatlands can vary by factors of 2-4 between years. This variability is clear in atmospheric measurements of the gas, but a lack of ground-based data is making it hard to locate the methane sources responsible. Methane monitoring in the Arctic is expensive, requiring sophisticated analysis equipment such as power requiring laser spectrometer analysis made in remote places. This also puts demands on the logistics where infrastructures and field stations that offer line-power in the field are in high demand but very rarely found. Research projects therefore typically focus on one site, and run for a year or two. Longer term monitoring programs, which document climate, hydrology, phenology and population dynamics of birds and mammals, rarely include carbon fluxes since it is technically challenging to measure. One that does is the Greenland Ecosystem Monitoring program that started at the Zackenberg research station, which has recorded substantial methane flux variations for almost a decade in North-east Greenland. Such multi-year studies show that, while there is some connection between the amounts of methane released from one year to the next, accurate forecasting is difficult. They also highlight the importance of extending monitoring beyond the growing period into the frozen season, both in spring and autumn. A spatially distributed network of long-term monitoring stations in the Arctic, with consistency between measurements, is badly needed to improve this situation. Productive methane 'hot spots', many sporadic, have also been identified in recent studies. By ventilating

  4. Relationship between Trophic Status and Methanogenic Pathways in Alaskan Peatlands

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Liu, X.; Sidelinger, W.; Wang, Y.; Hines, M. E.; Langford, L.; Chanton, J.

    2015-12-01

    To improve predictions of naturally emitted CH4 from northern wetlands, it is necessary to further examine the methanogenic pathways in these wetlands. Stable isotope C ratios (δ13C) have been used as a robust tool to distinguish different pathways, but different sources of parent compounds (acetate and CO2) with unique δ13C may add complexity to previously established criteria. Large portions of peatlands accommodate a mixture of different sphagna and sedges. Plant species may look very similar and belong to the same genus but are different morphologically and physiologically. To better understand the relationships between surface vegetation patterns and methanogenic pathways, 26 peatland sites were studied in Fairbanks and Anchorage, Alaska in summers of 2014 and 2015. These sites were ordinated using multiple factor analysis into 3 clusters based on pH, temp, CH4 and volatile fatty acids production rates, δ13C values, and surface vegetation species/pattern. In the low-pH trophic cluster (pH~3.5), non-vascular/vascular plant ratios (NV/V) were ~ 0.87 and dominated by diverse Sphagnum species and specific sedges (Eriophorum vaginatum), and fermentation was the dominant end-point in decomposition with no CH4 detected. Although NV/V is about the same in the intermediate cluster (0.74) (pH~4.5), and Sphagnum squarrosum was largely present, both hydrogenotrophic (HM) and acetoclastic methanogenesis (AM) were very active. Syntrophy was present at certain sites, which may provide CO2 with unique δ13C for CH4 production. At the highest pH trophic cluster examined in this study (pH~5), non-vascular plants were almost not existent and Carex aquatilis dominated. CH4 production rates (mainly HM) were slower than those in the intermediate cluster and the apparent fractionation factor a was lower than in the sites with syntrophy, which warrants further investigation of the position and compound specific δ13C analysis of volatile fatty acids.

  5. Modelling Seasonal Carbon Dynamics on Fen Peatlands

    NASA Astrophysics Data System (ADS)

    Giebels, Michael; Beyer, Madlen; Augustin, Jürgen; Roppel, Mario; Juszczak, Radoszlav; Serba, Tomasz

    2010-05-01

    In Germany more than 99 % of fens have lost their carbon and nutrient sink function due to heavy drainage and agricultural land use especially during the last decades and thus resulted in compression and heavy peat loss (CHARMAN 2002; JOOSTEN & CLARKE 2002; SUCCOW & JOOSTEN 2001; AUGUSTIN et al. 1996; KUNTZE 1993). Therefore fen peatlands play an important part (4-5 %) in the national anthropogenic trace gas budget. But only a small part of drained and agricultural used fens in NE Germany can be restored. Knowledge of the influence of land use to trace gas exchange is important for mitigation of the climate impact of the anthropogenic peatland use. We study carbon exchanges between soil and atmosphere on several fen peatland use areas at different sites in NE-Germany. Our research covers peatlands of supposed strongly climate forcing land use (cornfield and intensive pasture) and of probably less forcing, alternative types (meadow and extensive pasture) as well as rewetted (formerly drained) areas and near-natural sites like a low-degraded fen and a wetted alder woodland. We measured trace gas fluxes with manual and automatic chambers in periodic routines since spring 2007. The used chamber technique bases on DROESLER (2005). In total we now do research at 22 sites situated in 5 different locations covering agricultural, varying states of rewetted and near-natural treatments. We present results of at least 2 years of measurements on our site of varying types of agricultural land use. There we found significant differences in the annual carbon balances depending on the genesis of the observed sites and the seasonal dynamics. Annual balances were constructed by applying single respiration and photosynthesis CO2 models for each measurement campaign. These models were based on LLOYD-TAYLOR (1994) and Michaelis-Menten-Kinetics respectively. Crosswise comparison of different site treatments combined with the seasonal environmental observations give good hints for the

  6. Effect of Soil Frost on Snow-melt runoff Generation: Stable Isotope Study in Drained Peatlands

    NASA Astrophysics Data System (ADS)

    Eskelinen, Riku; Ronkanen, Anna-Kaisa; Marttila, Hannu; Kløve, Bjørn

    2013-04-01

    In this study, we analysed stable isotopes and water quality of runoff water collected daily from two different peatland drainage areas with automated samplers from March 2012 to October 2012, located in Northern Finland. In addition we collected weekly snow samples for stable isotope analysis. Our primary aim was to find out how different land use types, i) peat extraction area and ii) peatland forestry, are affecting the flow paths and runoff water quality during the snow melt period. Results show that there is a clear difference in δO18 signal between these systems. The peatland forestry area is located at groundwater dominated area which can be seen as a flat line when δO18 values of all samples are plotted. Samples taken at the peat extraction area show a clear response to the snowmelt event. Most likely this difference is caused by different soil frost conditions. Quantity of the groundwater at the forestry area prevents the soil from freezing during winter, therefore water originating from melting snow is able to infiltrate to the peat soil and push pre-event water into the drainage system. This observation is also visible in water quality of runoff water as high peak in colour during the snow melt period. Contrary, the peat extraction area behaves in opposite way. Melting water from snow is not able to infiltrate to ditches but instead will rapidly move on the frozen soil surface as a Hortonian overland flow. Because the soil is frozen, moving water is not able to leach humic substances from soil layers or erode particulate matter from the soil surface. These observations can be used to develop water quality protection policies for drained peatland areas. In Northern areas, where freezing of soil during winter is common it is not crucial to emphasize water protection during spring snowmelt, as frozen soil helps to maintain the runoff water quality at reasonable levels. In the areas where ground frost is rarer the impact of purifying runoff water in spring

  7. Physical and chemical differences between natural and artificial pools in blanket peatlands

    NASA Astrophysics Data System (ADS)

    Turner, Ed; Baird, Andy; Billett, Mike; Chapman, Pippa; Dinsmore, Kerry; Holden, Joseph

    2014-05-01

    Natural pools are common features of many northern peatlands. Numerous artificial pools are being created behind dams installed during drain-blocking, a common peatland restoration technique, significantly increasing the area of open water. Natural pools are known to be major sources of GHGs (e.g. Hamilton et al. 1994), but the reasons they are such 'hotspots' is poorly understood. We hypothesize that pools act as 'biochemical reactors' of particulate and dissolved organic carbon (POC and DOC) transported from surrounding peat that is processed into a range of products including CH4 and CO2. Therefore, understanding the processes operating in both natural and artificial pool systems is fundamental to elucidating this hypothesis. Water levels and temperature have been continuously monitored at six natural and six artificial pools within the 'Flow Country' blanket peatland in northern Scotland since May 2013. Bi-weekly sampling of waters from pools, peat matrix through-flow (via piezometers) and surface flow has been conducted for analysis of DOC, POC, DIC, CH4diss and CO2diss, together with GHG flux measurements from pool surfaces and adjacent peat. We show that, to date, pool water levels rapidly respond to rainfall, although artificial pools appear to respond with greater magnitude. For example, over the course of same rainfall event (20-23 June 2013), natural and artificial pool levels increased between 5.3 and 9.8 cm, and 12.5 and 22.6 cm respectively. Temperature measured at c. 5 cm from the base of each pool shows distinct diurnal fluctuations, which are of greater magnitude in all but one of the natural pools compared to the artificial pools: over the same period (20-23 July 2013), the maximum diurnal variation at the artificial pool site was 5.1 °C compared to 9.2 °C within the natural pools. Vegetation cover is generally higher in artificial pools and may have a moderating effect on variations in pool temperature. Results of pool-water DOC analysis from

  8. Effects of Permafrost Thaw on Net Ecosystem Carbon Balance in a Subarctic Peatland

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Roulet, N. T.; Moore, T. R.

    2014-12-01

    This research is to assess changes in net ecosystem carbon balance (NECB) with permafrost thaw in northern peatland: in particular how changes in C biogeochemistry influence NECB. Thawed transects associated with varying stages of permafrost thaw: from palsas with intact permafrost (P), through edge of palsa (EP), dry lawn (DL), wet lawn (WL), edge of thawed pond (ET), pond sedges (PS), to several thawed ponds (TP) in a subarctic peatland in northern Quebec were sampled in the snow free seasons of 2013 and 2014. The exchange of CO2 and CH4, vegetation, dissolved organic C (DOC) concentration and biodegradability, active layer depth, air and peat temperatures, water table depth (WT), pH, and conductivity were measured. Peat temperatures were quite similar among different locations, but the WT decreased significantly along the transect creating varied environmental conditions that supporting different plant communities. From dry to wet area, vegetation abundance and biomass showed reductions of shrubs and lichens, and increases of Sphagnum, grasses and sedges. Pore water pH increased from dry to wet area, and conductivity slightly decreased. Wet thaw area WL, ET and PS had relatively higher season gross ecosystem production (GEP) and higher season ecosystem respiration (ER), but relative similar net ecosystem CO2 exchange (NEE). Only TP had a significant higher positive season NEE. Palsa was the only CH4 sink, and quite high CH4 emissions were found after it thawed. CH4-C release significantly increased from dry to wet in thawed area, which even several times bigger than total C exchange in ET and PS. Generally, wet area had higher DOC concentration and higher DOC biodegradability indicated by lower SUVA254 (except PS which received great influence from pond). All components in the NECB (GEP, ER, CH4, DOC) increased significantly in magnitude from palsa to wet thawed area, and ecosystem C sink turned into source as palsa thawed into PS and TP. These results

  9. A reconstruction of vegetation and paleohydrologycal changes from peatland in Kansk forest-steppe, Yenisei Siberia

    NASA Astrophysics Data System (ADS)

    Rodionova, Alexandra

    2016-04-01

    Peatlands are an important natural archive for past climatic changes. Climatic changes throughout the Holocene have been reconstructed from peat using a wide array of biological and other proxies. Many different proxy indicators can be derived from peat cores allowing for a multi-proxy approach to climatic reconstructions. Peat-based climatic and environmental reconstructions are currently available from many sites in Yenisei Siberia, mainly for its northern territories. The purpose of this paper is to study some features of peatland development and environmental reconstructions from the Holocene period in the south part of Yenisei Siberia (Kansk forest-steppe zone). The main method used in this research is macrofossil analysis. It can be used to reconstruct the development of local vegetation and surface wetness on peatlands. The macrofossil analysis in the peat resulted from the study of the vegetation in a particular place over a period of time, and it allowed the reconstruction of environmental changes that have occurred since the Late Glacial. Then we used ecological scales of moisture and reconstructed surface wetness for the entire period of the bog formation. Radiocarbon dating was carried out at Sobolev Institute of Geology and Mineralogy, Russian Academy of Sciences, Novosibirsk . Peatland "Pinchinskoye" was selected for investigation in Kansk forest-steppe. It is located on the right bank of the Yenisei River in the floodplain of Esaulovka River. Peat cores of 350 cm were selected in the southern part of the peatbog, including 225 cm of peat (with loam layers in the range of 90 to 135 cm), 75 cm of organic and mineral sapropel with the inclusion of fossil shells of mollusks and different plant macrofossils and 50 cm of the loam below. The process of peat accumulation dated back 8400 ± 140 years, which is the oldest date for the forest-steppe zone of Yenisei Siberia. The climate of Boreal period of the Holocene was chilly. Under these conditions, in the

  10. Decision analysis of mitigation and remediation of sedimentation within large wetland systems: a case study using Agassiz National Wildlife Refuge

    USGS Publications Warehouse

    Post van der Burg, Max; Jenni, Karen E.; Nieman, Timothy L.; Eash, Josh D.; Knutsen, Gregory A.

    2014-01-01

    Sedimentation has been identified as an important stressor across a range of wetland systems. The U.S. Fish and Wildlife Service has the responsibility of maintaining wetlands within its National Wildlife Refuge System for use by migratory waterbirds and other wildlife. Many of these wetlands could be negatively affected by accelerated rates of sedimentation, especially those located in agricultural parts of the landscape. In this report we document the results of a decision analysis project designed to help U.S. Fish and Wildlife Service staff at the Agassiz National Wildlife Refuge (herein referred to as the Refuge) determine a strategy for managing and mitigating the negative effects of sediment loading within Refuge wetlands. The Refuge’s largest wetland, Agassiz Pool, has accumulated so much sediment that it has become dominated by hybrid cattail (Typha × glauca), and the ability of the staff to control water levels in the Agassiz Pool has been substantially reduced. This project consisted of a workshop with Refuge staff, local and regional stakeholders, and several technical and scientific experts. At the workshop we established Refuge management and stakeholder objectives, a range of possible management strategies, and assessed the consequences of those strategies. After deliberating a range of actions, the staff chose to consider the following three strategies: (1) an inexpensive strategy, which largely focused on using outreach to reduce external sediment inputs to the Refuge; (2) the most expensive option, which built on the first option and relied on additional infrastructure changes to the Refuge to increase management capacity; and (3) a strategy that was less expensive than strategy 2 and relied mostly on existing infrastructure to improve management capacity. Despite the fact that our assessments were qualitative, Refuge staff decided they had enough information to select the third strategy. Following our qualitative assessment, we discussed

  11. Contaminated sediment dynamics in peatland headwaters

    NASA Astrophysics Data System (ADS)

    Shuttleworth, Emma; Clay, Gareth; Evans, Martin; Hutchinson, Simon; Rothwell, James

    2016-04-01

    Peatlands are an important store of soil carbon, provide multiple ecosystem services, and when located in close proximity to urban and industrial areas, can also act as sinks of atmospherically deposited heavy metals. The near-surface layer of the blanket peats of the Peak District National Park, UK, is severely contaminated with high concentrations of anthropogenically derived, atmospherically deposited lead (Pb). These peats are severely degraded, and there is increasing concern that erosion is releasing considerable quantities of this legacy pollution into surface waters. Despite substantial research into Pb dynamics in peatlands formal description of the possible mechanisms of contaminated sediment mobilisation is limited. However, there is evidence to suggest that a substantial proportion of contaminated surface sediment may be redistributed elsewhere in the catchment. This study uses the Pb contamination stored near the peat's surface as a fingerprint to trace contaminated sediment dynamics and storage in three severely degraded headwater catchments. Erosion is exposing high concentrations of Pb on interfluve surfaces, and substantial amounts of reworked contaminated material are stored on other catchment surfaces (gully walls and floors). We propose a variety of mechanisms as controls of Pb release and storage on the different surfaces, including: (i) wind action on interfluves; (ii) the aspect of gully walls, and (iii) gully depth. Vegetation also plays an important role in retaining contaminated sediment on all surfaces.

  12. Upscaling methane emission hotspots in boreal peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, Fabio; Runkle, Benjamin R. K.; Brücher, Tim; Kleinen, Thomas; Brovkin, Victor

    2016-03-01

    Upscaling the properties and effects of small-scale surface heterogeneities to larger scales is a challenging issue in land surface modeling. We developed a novel approach to upscale local methane emissions in a boreal peatland from the micro-topographic scale to the landscape scale. We based this new parameterization on the analysis of the water table pattern generated by the Hummock-Hollow model, a micro-topography resolving model for peatland hydrology. We introduce this parameterization of methane hotspots in a global model-like version of the Hummock-Hollow model that underestimates methane emissions. We tested the robustness of the parameterization by simulating methane emissions for the next century, forcing the model with three different RCP scenarios. The Hotspot parameterization, despite being calibrated for the 1976-2005 climatology, mimics the output of the micro-topography resolving model for all the simulated scenarios. The new approach bridges the scale gap of methane emissions between this version of the model and the configuration explicitly resolving micro-topography.

  13. Upscaling methane emission hotspots in boreal peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, F.; Runkle, B. R. K.; Brücher, T.; Kleinen, T.; Brovkin, V.

    2015-10-01

    Upscaling the properties and the effects of small-scale surface heterogeneities to larger scales is a challenging issue in land surface modeling. We developed a novel approach to upscale local methane emissions in a boreal peatland from the micro-topographic scale to the landscape-scale. We based this new parameterization on the analysis of the water table pattern generated by the Hummock-Hollow model, a micro-topography resolving model for peatland hydrology. We introduce this parameterization of methane hotspots in a global model-like version of the Hummock-Hollow model, that underestimates methane emissions. We tested the robustness of the parameterization by simulating methane emissions for the next century forcing the model with three different RCP scenarios. The Hotspot parameterization, despite being calibrated for the 1976-2005 climatology, mimics the output of the micro-topography resolving model for all the simulated scenarios. The new approach bridges the scale gap of methane emissions between this version of the model and the configuration explicitly resolving micro-topography.

  14. Testing a new version of the DigiBog model to explore the differential response of peatland microforms to shifts in surface wetness

    NASA Astrophysics Data System (ADS)

    Garneau, Michelle; Baird, Andrew J.; Morris, Paul J.; van Bellen, Simon

    2016-04-01

    Over the last decades, many hypotheses have been put forward to explain pool formation in northern peatlands including topographic, biotic or climatic factors. Several studies suggest that pool formation is primarily controlled by autogenic, edaphic and topographic factors rather than external climatic influences (allogenic factors). However, there is still no consensus to explain pool formation and to confirm whether their initiation is primarily associated with autogenic or allogenic processes. Subarctic fens in northeastern Canada are characterized by a patterned surface of pools, flarks and narrow strings. Due to their geographic location at the northern ombrotrophic peatland distribution, these poor fens have been highly sensitive to hydroclimatic variations that influenced pool development and expansion. Our data indicate that wet hollows or shallow pools developed at minimal ages between ca 4200 cal BP and ca 2500 cal BP. We hypothesize that pool developed as secondary features under wetter and cooler conditions that (i) caused shorter growing seasons which negatively impacted on peat accumulation and (ii) led to lower rates of evaporation, and that (i) and (ii) in combination led to increased surface wetness. The differential response of microforms to shifts in surface wetness show the complexity of processes involved in pool initiation. A recent version of the DigiBog model (Morris et al, 2015), that allows for sub-seasonal variations in precipitation and evaporation, is used to explore the interactions between climate, growing season, peat productivity, peat hydraulic properties and water-table behaviour. Model results suggest that decreases in growing season length, combined with decreases in evapotranspiration, can explain long-lived shifts to wetter conditions in peatlands. If evapotranspiration is reduced but growing season does not vary, long-lived shifts in peatland wetness are less likely and the peatland instead tends to show a homeostatic

  15. Holocene tephrostratigraphy in high-latitude peatlands of the Southern Hemisphere: a link through time?

    NASA Astrophysics Data System (ADS)

    Roland, T. P.; Amesbury, M. J.; Charman, D.; De Vleeeschouwer, F.; Hodgson, D.; Hughes, P. D. M.; Mauquoy, D.; Piotrowska, N.; Royles, J.; van Bellen, S.; Vanneste, H.

    2014-12-01

    We present preliminary tephrostratigraphic data from south Patagonian peatlands and moss banks from the Antarctic Peninsula that provide greater chronological constraint to Holocene palaeoclimatic records and increase the potential for inter-regional correlation. Relative to the Northern Hemisphere, there is a paucity of high-resolution, robustly dated Holocene palaeoclimate records in the Southern Hemisphere, limiting our ability to validate climate models in this region and fully understand variation in the global climate system over time. In the absence of long-term instrumental data, multi-proxy (testate amoebae, plant macrofossils, δ13C, δ18O and δD) palaeoclimatic records from south Patagonian peatlands can provide valuable information about the long-term variability of the southern westerlies, a key component in determining the Southern Ocean's function as a sink or source of atmospheric carbon dioxide. Similarly, multi-proxy palaeoclimatic reconstructions from moss banks provide a unique terrestrial palaeoenvironmental archive from the Antarctic Peninsula, where records of past ecological change are rare and provide vital context for the recent, rapid biotic change recorded since the mid-20th century. Robust chronologies are imperative for the accurate examination of spatial and temporal patterns in Holocene climate variation. Previous work has confirmed the presence of discrete tephra horizons in south Patagonian peatlands and Antarctic Peninsula moss banks but the examination of distal, cryptotephras is currently underemployed as a geochronological tool. The chronological potential of these archives is considerable, given their high and largely continuous accumulation rates and suitability for 14C dating, presenting additional opportunities to refine the ages of major Holocene eruptions. Here, we present initial tephrostratigraphic results from both regions and explore the links between them.

  16. Elemental, stable isotopic and biochemical characterization of soil organic matter alteration across a natural peatland gradient

    NASA Astrophysics Data System (ADS)

    Cowie, G.; Mowbray, S.; Belyea, L.; Laing, C.; Allton, K.; Abbott, G.; Muhammad, A.

    2010-12-01

    Northern peatlands store around one third of global soil C and thus represent a key reservoir. To elucidate how these systems might respond to climate change, field- and laboratory-based experimental incubation studies are being conducted at sites across a natural peatland gradient in the boreonemoral zone of central Sweden (Ryggmossen). The site comprises four successional stages, from edge to centre; Swamp Forest (SF), Lagg Fen (LF), Bog Margin (BM) and Bog Plateau (BP). The well-preserved succession shows strong decreases in mineral cations and pH, and distinct changes in vegetation and water-table depth. As an underpinning to these experiments, comprehensive characterization of natural soil organic matter (SOM) alteration has been carried out through detailed analyses of vegetation and downcore profiles at contrasting topographic sites (hummock vs hollow) in each of the four locations. As illustrated in Figure 1, while some similarities occur in downcore trends, contrasts are observed in C and N elemental and stable isotopic compositions, between stages and, in some cases, between microtopographic settings. Downcore trends and intersite differences are also observed in biochemical yields and molecular composition (carbohydrates, amino acids, phenols, lipids and D/L amino acid ratios). These reflect SOM decay and alteration combined with the effects of contrasting hydrologic, redox and nutrient regimes and differing vegetation and microbial inputs at each of the study sites. Multivariate analysis is used to to elucidate compositional patterns that characterize and delineate progressive SOM decay, specific vegetation types, and the effects of contrasting environmental conditions at the different sites. Figure 1. A. Organic carbon content (wt %), B. Atomic ratio of organic C to total N, C. Stable C isotopic composition of organic C (d13Corg), and D. Stable N isotopic composition of total nitrogen (d15N), all for core profiles from contrasting settings (hummock and

  17. CO2 and CH4 isotope compositions and production pathways in a tropical peatland

    NASA Astrophysics Data System (ADS)

    Holmes, M. Elizabeth; Chanton, Jeffrey P.; Tfaily, Malak M.; Ogram, Andrew

    2015-01-01

    While it is widely recognized that peatlands are important in the global carbon cycle, there is limited information on belowground gas production in tropical peatlands. We measured pore water methane (CH4) and carbon dioxide (CO2) concentrations and δ13C isotopic composition and CH4 and CO2 production rates in peat incubations from the Changuinola wetland in Panama. Our most striking finding was that CH4 was depleted in 13C (-94‰ in pore water and produced at -107‰ in incubated peat) relative to CH4 found in most temperate and northern wetlands, potentially impacting the accuracy of approaches that use carbon isotopes to constrain global mass balance estimates. Fractionation factors between CH4 and CO2 showed that hydrogenotrophic methanogenesis was the dominant CH4 production pathway, with up to 100% of the CH4 produced via this route. Far more CO2 than CH4 (7 to 100X) was measured in pore water, due in part to loss of CH4 through ebullition or oxidation and to the production of CO2 from pathways other than methanogenesis. We analyzed data on 58 wetlands from the literature to determine the dominant factors influencing the relative proportions of CH4 produced by hydrogenotrophic and acetoclastic methanogenesis and found that a combination of environmental parameters including pH, vegetation type, nutrient status, and latitude are correlated to the dominant methanogenic pathway. Methane production pathways in tropical peatlands do not correlate with these variables in the same way as their more northerly counterparts and thus may be differently affected by climate change.

  18. Rebuilding Peatlands on Mineral Soils Utilizing Lessons Learned from Past Peatland Initiation

    NASA Astrophysics Data System (ADS)

    Vitt, D. H.; Koropchak, S. C.; Xu, B.; Bloise, R.; Wieder, R.; Mowbray, S.

    2010-12-01

    Recent surveys of peatland initiation during the past 10,000 years in northeastern Alberta have revealed that nearly all peatlands, regardless of whether they are currently bogs and fens, were initiated by paludification, or swamping of upland soils. Terrestrialization (or infilling of water bodies) rarely if ever was involved in the initiation of peatlands across the mid boreal of Canada. Although the importance of paludification as a significant natural process in the initiation of peatland ecosystems has long been known by peatland ecologists, this knowledge has not been transferred to peatland and wetland restoration methodologies. We initiated this study to determine if wetland structure and function could be re-established on mineral gas/oil pads that were originally placed on organic soils. We have attempted to emulate the paludification process by removing mineral material to near the surrounding peatland natural water level and introducing a suite of wetland plants to the rewetted mineral soils. The experimental design comprised two well sites at the Shell Carmon Creek in situ plant near Peace River, Alberta. We placed 292 2 x 2 m plots over a series of fertilizer, water level, cultivation, and amendment treatments. In this presentation, we address four questions: 1) Will locally available peatland vascular plant species establish on these wet, compacted, mineral soils? If so; 2) Are species responses affected by water level, amendment, cultivation, and fertilization treatments, 3) Are invasive weeds a concern in these re-establishment trials, and 4) Will the surrounding bog water chemistry have an effect on water in contact with the mineral soils? Results after three growing season are: 1) All three species originally planted (a sedge, a willow, and tamarack) have successfully established at both well sites; 2) Carex aquatilis has performed well and responses to differing water levels and cultivation are not significant; 3) The plant responses to

  19. Multiple factors affect a population of Agassiz's desert tortoise (Gopherus agassizii) in the Northwestern Mojave Desert

    USGS Publications Warehouse

    Berry, Kristin H.; Yee, Julie L.; Coble, Ashley A.; Perry, William M.; Shields, Timothy A.

    2013-01-01

    Numerous factors have contributed to declines in populations of the federally threatened Agassiz's Desert Tortoise (Gopherus agassizii) and continue to limit recovery. In 2010, we surveyed a low-density population on a military test facility in the northwestern Mojave Desert of California, USA, to evaluate population status and identify potential factors contributing to distribution and low densities. Estimated densities of live tortoises ranged spatially from 1.2/km2 to 15.1/km2. Although only one death of a breeding-age tortoise was recorded for the 4-yr period prior to the survey, remains of 16 juvenile and immature tortoises were found, and most showed signs of predation by Common Ravens (Corvus corax) and mammals. Predation may have limited recruitment of young tortoises into the adult size classes. To evaluate the relative importance of different types of impacts to tortoises, we developed predictive models for spatially explicit densities of tortoise sign and live tortoises using topography (i.e., slope), predators (Common Raven, signs of mammalian predators), and anthropogenic impacts (distances from paved road and denuded areas, density of ordnance fragments) as covariates. Models suggest that densities of tortoise sign increased with slope and signs of mammalian predators and decreased with Common Ravens, while also varying based on interaction effects involving these predictors as well as distances from paved roads, denuded areas, and ordnance. Similarly, densities of live tortoises varied by interaction effects among distances to denuded areas and paved roads, density of ordnance fragments, and slope. Thus multiple factors predict the densities and distribution of this population.

  20. Increases in methylmercury export from a sulfate-amended peatland: A consequence of an altered microbial consortia?

    NASA Astrophysics Data System (ADS)

    Branfireun, B.; Krabbenhoft, D.; Fowle, D.; Jeremiason, J.

    2004-05-01

    An experiment at the Marcell Experimental Forest, Minnesota is ongoing to test the hypothesis that increased atmospheric sulfate deposition to northern peatlands is responsible for increased methylmercury yields from these ecosystems. A peatland, divided into an upslope control portion and a downslope experimental portion, has had elevated levels of sulfate applied to the experimental portion using an extensive irrigation network for several seasons. Increases in methylmercury yield from the system were apparent early in the experimental manipulation. In 2002, peat cores were extracted from the control and experimental areas of the peatland to evaluate whether or not changes in the peat sulfur geochemistry, microbial community structure, and/or mercury methylation potential could be attributed to the sulfate additions. Mercury methylation potential was assessed using a stable isotope addition to incubated intact peat cores, which were subsequently sliced and frozen until analyses. The microbial community structure was assessed using a modified solid-phase extraction followed by phospholipid fatty acid (PLFA) analyses. Although only minor differences in sulfur geochemistry and methylation potential were detected, the treatment cores had increased abundances of Desulfovibrio-group and Desulfobacter-group biomarkers compared to the control cores, and the effect was greatest in the near surface peat. In the control cores, the abundances of sulfate-reducers in both groups increased with depth. These results suggest that increased sulfate loading may cause a shift in microbial community structure and abundance in favour of known mercury methylators.

  1. Methods for assessing the quality of runoff from Minnesota peatlands

    SciTech Connect

    Clausen, J.C.

    1981-01-01

    The quality of runoff from large, undisturbed peatlands in Minnesota is chaaracterized and sampling results from a number of bogs (referred to as a multiple watershed approach) was used to assess the effects of peat mining on the quality of bog runoff. Runoff from 45 natural peatlands and one mined bog was sampled five times in 1979-80 and analyzed for 34 water quality characteristics. Peatland watersheds were classified as bog, transition, or fen, based upon both water quality and watershed characteristics. Alternative classification methods were based on frequency distributions, cluster analysis, discriminant analysis, and principal component analysis results. A multiple watershed approach was used as a basis of drawing inferences regarding the quality of runoff from a representative sample of natural bogs and a mined bog. The multiple watershed technique applied provides an alternative to long-term paired watershed experiments in evaluating the effects of land use activities on the quality of runoff from peatlands in Minnesota.

  2. Peatland classification of West Siberia based on Landsat imagery

    NASA Astrophysics Data System (ADS)

    Terentieva, I.; Glagolev, M.; Lapshina, E.; Maksyutov, S. S.

    2014-12-01

    Increasing interest in peatlands for prediction of environmental changes requires an understanding of its geographical distribution. West Siberia Plain is the biggest peatland area in Eurasia and is situated in the high latitudes experiencing enhanced rate of climate change. West Siberian taiga mires are important globally, accounting for about 12.5% of the global wetland area. A number of peatland maps of the West Siberia was developed in 1970s, but their accuracy is limited. Here we report the effort in mapping West Siberian peatlands using 30 m resolution Landsat imagery. As a first step, peatland classification scheme oriented on environmental parameter upscaling was developed. The overall workflow involves data pre-processing, training data collection, image classification on a scene-by-scene basis, regrouping of the derived classes into final peatland types and accuracy assessment. To avoid misclassification peatlands were distinguished from other landscapes using threshold method: for each scene, Green-Red Vegetation Indices was used for peatland masking and 5th channel was used for masking water bodies. Peatland image masks were made in Quantum GIS, filtered in MATLAB and then classified in Multispec (Purdue Research Foundation) using maximum likelihood algorithm of supervised classification method. Training sample selection was mostly based on spectral signatures due to limited ancillary and high-resolution image data. As an additional source of information, we applied our field knowledge resulting from more than 10 years of fieldwork in West Siberia summarized in an extensive dataset of botanical relevés, field photos, pH and electrical conductivity data from 40 test sites. After the classification procedure, discriminated spectral classes were generalized into 12 peatland types. Overall accuracy assessment was based on 439 randomly assigned test sites showing final map accuracy was 80%. Total peatland area was estimated at 73.0 Mha. Various ridge

  3. The role of topography and vegetation cover upon riverine dissolved organic carbon and water colour in peatlands

    NASA Astrophysics Data System (ADS)

    Parry, Lauren; Chapman, Pippa; Palmer, Shiela; Wallage, Zoe; Whynn, Hannah; Holden, Joseph

    2015-04-01

    Riverine dissolved organic carbon (DOC) is predominantly controlled by soil type and previous research has shown that peatlands are an important source. However, little is known about the controls upon riverine DOC that have not undergone major disturbance from drainage or burning in blanket peatlands. Vegetation cover and topographic characteristics of 119 peatland catchments in northern England were determined across three basins using 0.5 m resolution colour infrared aerial images and digital elevation models respectively. These characteristics were then linked to DOC and water colour levels from their respective catchments gathered during six repeated sampling campaigns. The topographic characteristics of slope standard deviation and mean slope were shown to be the strongest (and negative) controls on DOC and water colour using stepwise regression. Bare peat and Ericaceous shrubs showed a weak but positive role in determining riverine DOC in a number of the models. There were a number of differences in model output depending on the basin. For example, Ericaceous shrubs were notably a more dominant control in one basin, but despite their presence, they did not feature in the regression models for the other two basins. The strength of topographic predictors in our study, together with the weaker role of vegetation type, is of use to water companies who source water from blanket peatland covered catchments and who wish to develop tools to justify land management decisions at spatial scales relevant to the practitioner. For example, it is possible to predict simply from DEMs and aerial imagery which tributaries will produce lower DOC concentrations and water colour and therefore which areas may be most suitable for raw water intakes.

  4. Investigating late Holocene variations in hydroclimate and the stable isotope composition of precipitation using southern South American peatlands: a hypothesis

    NASA Astrophysics Data System (ADS)

    Daley, T. J.; Mauquoy, D.; Chambers, F. M.

    2012-02-01

    Ombrotrophic raised peatlands provide an ideal archive for integrating late Holocene records of variations in hydroclimate and the estimated stable isotope composition of precipitation with recent instrumental measurements. Modern measurements of mean monthly surface air temperature, precipitation and δD and δ18O values in precipitation from the late twentieth and early twenty-first centuries provide a short but invaluable record with which to investigate modern relationships between these variables, thereby enabling improved interpretation of the peatland palaeodata. Data from two stations in the Global Network for Isotopes in Precipitation (GNIP) from Tierra del Fuego (Punta Arenas, Chile and Ushuaia, Argentina) were analysed for the period 1982 to 2008. In both locations, δD and δ18O values have decreased in response to quite different trends in local surface air temperature and total precipitation amount. At Ushuaia, the fall in δ18O values is associated with an increase in the mean annual amount of precipitation. At Punta Arenas, the fall in δ18O values is weakly associated with decrease in the precipitation amount and an increase in local temperatures. The pattern in both records is consistent with an increase in the zonal intensity of the southern westerly wind belt. These regional differences, observed in response to a known driver, should be detectable in peatland sites close to the GNIP stations. There is currently insufficient availability of suitably temporally resolved data to test for these regional differences over the last 3000 yr. Existing peatland palaeoclimate data from two sites near Ushuaia, however, provide evidence for changes in the late Holocene that are consistent with the pattern observed in modern observations. Furthermore, the records suggest synchroneity in millennial-scale oscillations between the Northern and Southern Hemispheres.

  5. The cascade of C:N:P stoichiometry in an ombrotrophic peatland: from plants to peat

    NASA Astrophysics Data System (ADS)

    Wang, Meng; Moore, Tim R.; Talbot, Julie; Richard, Pierre J. H.

    2014-01-01

    Northern peatlands are important carbon (C) sinks and while the patterns of C accumulation have been frequently investigated, nitrogen (N) and phosphorus (P) accumulation are often neglected. Here we link the C:N:P stoichiometry from foliar plant tissues, through senescent litters to peat, and determine C, N and P accumulation rates at Mer Bleue Bog, eastern Canada. Average C:N:P ratios changed from 794:17:1 in the foliar tissues to 911:10:1 in litter and 1285:32:1 in acrotelm peat. The increase in C:N and C:P ratios from mature to senescent tissues is related to nutrient resorption. The increase in C:P and N:P ratios in peat, which was contrary to that observed in Canadian forest soils, may be related to plant/mycorrhizae uptake of P. The long-term apparent rates of C, N and P accumulation were 29.5 ± 2.1 (SE) g C, 0.87 ± 0.01 g N and 0.017 ± 0.002 g P m-2 yr-1, respectively. The significant correlation between the accumulation rates of N and P and that of C suggests more attention be placed on C:N:P stoichiometry in peatland biogeochemistry, in particular in understanding why C:P ratios are so large in the lower parts of the profile.

  6. Understanding diversity patterns in bacterioplankton communities from a sub-Antarctic peatland.

    PubMed

    Quiroga, María Victoria; Valverde, Angel; Mataloni, Gabriela; Cowan, Don

    2015-06-01

    Bacterioplankton communities inhabiting peatlands have the potential to influence local ecosystem functions. However, most microbial ecology research in such wetlands has been done in ecosystems (mostly peat soils) of the Northern Hemisphere, and very little is known of the factors that drive bacterial community assembly in other regions of the world. In this study, we used high-throughput sequencing to analyse the structure of the bacterial communities in five pools located in a sub-Antarctic peat bog (Tierra del Fuego, Argentina), and tested for relationships between bacterial communities and environmental conditions. Bacterioplankton communities in peat bog pools were diverse and dominated by members of the Proteobacteria, Actinobacteria, Bacteroidetes and Verrucomicrobia. Community structure was largely explained by differences in hydrological connectivity, pH and nutrient status (ombrotrophic versus minerotrophic pools). Bacterioplankton communities in ombrotrophic pools showed phylogenetic clustering, suggesting a dominant role of deterministic processes in shaping these assemblages. These correlations between habitat characteristics and bacterial diversity patterns provide new insights into the factors regulating microbial populations in peatland ecosystems. PMID:25727763

  7. Quantifying the Distribution and Landscape Controls of Peatlands and Organic Layer Thickness within Alaska

    NASA Astrophysics Data System (ADS)

    Wylie, B. K.; Pastick, N.; Jorgenson, T.; Nield, S.; Johnson, K. D.

    2014-12-01

    The northern circumpolar region is estimated to contain 50 % of the global belowground carbon pool and is experiencing climate change at rates higher than anywhere else globally. Surface organic horizons associated with these immense carbon pools are important to ecosystem functioning in terms of soil moisture and temperature regulations, permafrost degradation, successional trajectories, and soil respiration levels. However, fire-induced changes to surface organics and their distribution are poorly understood, especially on landscape scales. These ambiguities make future predictions uncertain for these significant carbon pools, which have the potential for significant feedbacks to global warming. Moreover, given the significant impacts and increasing severity and amount of fires in boreal systems, the spatial quantification of post-fire surface organic thickness is important for ecosystem model calibrations and comparisons, and can improve future projections of vegetation types and albedo, carbon stocks and fluxes, and future thaw depths. Here we present the results of pioneering studies that quantified the distribution and controls of peatlands and soil organic layer thickness in Alaska through the use of statistical models, field data, spatial analyses, and remote sensing (Landsat). Our empirical modeling approach enabled us to produce medium-resolution (30-m pixels) maps of peatlands and organic layer thickness throughout Alaska, which is important for land management practices and enhances the understanding of the risk and feedbacks associated with fires and climate feedbacks.

  8. Autochamber measurements of Net Ecosystem (CO2) Exchange at a subarctic mire in Northern Sweden

    NASA Astrophysics Data System (ADS)

    Walthall, M.; Parker-Smith, X.; Lawrence, R. D.; Crill, P. M.

    2015-12-01

    Northern latitude wetlands (>~50°N) are characterized by cold and wet conditions that result in low decomposition rates for plant litter. This process promotes the sequestration of carbon (C) in the form of organic matter (i.e. peat) and the formation of widespread peatands. Peatlands, particularly in the Northern Hemisphere, have accumulated C by removing atmospheric CO2 for approximately the past 10,000 years. Historically, peatlands represent a net C sink; however, increases in the global average temperature could alter peatlands ability to store carbon. With a warming climate and permafrost thaw, the pool of once stable soil organic C available for decomposition is increasing. Like all terrestrial ecosystems, a number of environmental factors (e.g. peat temperature and vegetation) play important roles in governing the fate of C in peatlands. Projected climate change is expected to affect these regulating factors. Subarctic peatlands in zones of discontinuous permafrost are experiencing widespread environmental changes due to climate warming. In this study, we present net ecosystem (CO2) exchange and δ13C-CO2 data from Stordalen Mire in northern Sweden (68°22'N, 19°03'E). Measurements were made using a quantum cascade laser spectrometer connected to automatic chambers placed in the three predominant ecosystems (a dry, elevated Palsa; an intermediate thaw regime dominated by Sphagnum spp. and; a completely thawed, inundated site dominated by Eriophorum angustifolium). Team was mentored by Mr. Ryan Lawrence from The University of New Hampshire.

  9. Peatland Carbon Accumulation in Southern Alaska During the Past 1000 Years: A Comparative Study of Hydrology and Carbon Accumulation in Four Peatlands

    NASA Astrophysics Data System (ADS)

    Klein, E. S.; Booth, R. K.; Yu, Z.

    2012-12-01

    North American peatlands are the largest C reservoir of any ecosystem type, and Alaskan peatlands contain greater than half of the C storage of United States' peatlands. Peatland C accumulation rates (PCAR) are controlled by the relative rates of production and decomposition, and the rate of these processes is affected by many factors, including temperature, hydrology, and vegetation. Understanding how this carbon pool will respond to climate changes is important for evaluating potential earth-system feedbacks. Critical to this goal is a better understanding of how PCAR varies among different climate zones and peatland types. We developed coupled studies of peatland paleohydrology and PCAR from four different Sphagnum-dominated peatlands in Alaska, two in the Southcentral (SC) region and two in the wetter and warmer Southeast (SE) region. Peatland types included a kettle peatland perched on a moraine and a lowland peatland occupying a paleo outwash channel in the SC region, as well as a raised peatland and a sloping peatland in the SE region. Past PCAR and hydrology of these peatlands, inferred from testate amoebae and loss-on-ignition analyses, were compared to well-documented climate and temperature changes of the past 1000 years, like the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). Results indicate heterogeneous patterns of PCAR at the four sites. For example, the raised peatland in the SE region had an average PCAR of 52 gC/m2/yr, whereas the other three sites had average values between 31-35 gC/m2/yr. Interestingly, testate amoebae indicated that the raised peatland had the driest average surface-moisture among the sites, possibly suggesting high temperature sensitivity to PCAR. Temporal patterns of PCAR also varied considerably among sites, with peatlands in the SE region exhibiting somewhat greater centennial-scale variability in PCAR during the past 1000 years than those of the SC region. Reconstructed water-table depths were also more

  10. Uplifting of palsa peatlands by permafrost identified by stable isotope depth profiles

    NASA Astrophysics Data System (ADS)

    Krüger, Jan Paul; Conen, Franz; Leifeld, Jens; Alewell, Christine

    2015-04-01

    Natural abundances of stable isotopes are a widespread tool to investigate biogeochemical processes in soils. Palsas are peatlands with an ice core and are common in the discontinuous permafrost region. Elevated parts of palsa peatlands, called hummocks, were uplifted by permafrost out of the influence of groundwater. Here we used the combination of δ15N values and C/N ratio along depth profiles to identify perturbation of these soils. In the years 2009 and 2012 we took in total 14 peat cores from hummocks in two palsa peatlands near Abisko, northern Sweden. Peat samples were analysed in 2 to 4 cm layers for stable isotope ratios and concentrations of C and N. The uplifting of the hummocks by permafrost could be detected by stable isotope depth patterns with the highest δ15N value at permafrost onset, a so-called turning point. Regression analyses indicated in 11 of 14 peat cores increasing δ15N values above and decreasing values below the turning point. This is in accordance with the depth patterns of δ13C values and C/N ratios in these palsa peatlands. Onset of permafrost aggradation identified by the highest δ15N value in the profile and calculated from peat accumulation rates show ages ranging from 80 to 545 years and indicate a mean (±SD) peat age at the turning points of 242 (±66) years for Stordalen and 365 (±53) years for Storflaket peatland. The mean peat ages at turning points are within the period of the Little Ice Age. Furthermore, we tested if the disturbance, in this case the uplifting of the peat material, can be displayed in the relation of δ15N and C/N ratio following the concept of Conen et al. (2013). In unperturbed sites soil δ15N values cover a relatively narrow range at any particular C/N ratio. Changes in N cycling, i.e. N loss or gain, results in the loss or gain of 15N depleted forms. This leads to larger or smaller δ15N values than usual at the observed C/N ratio. All, except one, turning point show a perturbation in the depth

  11. Fire and Microtopography in Peatlands: Feedbacks and Carbon Dynamics

    NASA Astrophysics Data System (ADS)

    Benscoter, B.; Turetsky, M. R.

    2011-12-01

    Fire is the dominant natural disturbance in peatland ecosystems. Over the past decade, peat fires have emerged as an important issue for global climate change, human health, and economic loss, largely due to the extreme peat fire events in Indonesia and Russia that severely impacted metropolitan areas and social infrastructure. However, the impact and importance of fire in peatland ecosystems are more far-reaching. Combustion of vegetation and soil organic matter releases an average of 2.2 kg C m-2 to the atmosphere, primarily as CO2, as well as a number of potentially harmful emissions such as fine particulate matter and mercury. Additionally, while peatlands are generally considered to be net sinks of atmospheric carbon, the removal of living vegetation by combustion halts primary production following fire resulting in a net loss of ecosystem carbon to the atmosphere for several years. The recovery of carbon sink function is linked to plant community succession and development, which can vary based on combustion severity and the resulting post-fire microhabitat conditions. Microtopography has a strong influence on fire behavior and combustion severity during peatland wildfires. In boreal continental peatlands, combustion severity is typically greatest in low-lying hollows while raised hummocks are often lightly burned or unburned. The cross-scale influence of microtopography on landscape fire behavior is due to differences in plant community composition between microforms. The physiological and ecohydrological differences among plant communities result in spatial patterns in fuel availability and condition, influencing the spread, severity, and type of combustion over local to landscape scales. In addition to heterogeneous combustion loss of soil carbon, this differential fire behavior creates variability in post-fire microhabitat conditions, resulting in differences in post-fire vegetation succession and carbon exchange trajectories. These immediate and legacy

  12. New approaches to the restoration of shallow marginal peatlands.

    PubMed

    Grand-Clement, E; Anderson, K; Smith, D; Angus, M; Luscombe, D J; Gatis, N; Bray, L S; Brazier, R E

    2015-09-15

    Globally, the historic and recent exploitation of peatlands through management practices such as agricultural reclamation, peat harvesting or forestry, have caused extensive damage to these ecosystems. Their value is now increasingly recognised, and restoration and rehabilitation programmes are underway to improve some of the ecosystem services provided by peatlands: blocking drainage ditches in deep peat has been shown to improve the storage of water, decrease carbon losses in the long-term, and improve biodiversity. However, whilst the restoration process has benefitted from experience and technical advice gained from restoration of deep peatlands, shallow peatlands have received less attention in the literature, despite being extensive in both uplands and lowlands. Using the experience gained from the restoration of the shallow peatlands of Exmoor National Park (UK), and two test catchments in particular, this paper provides technical guidance which can be applied to the restoration of other shallow peatlands worldwide. Experience showed that integrating knowledge of the historical environment at the planning stage of restoration was essential, as it enabled the effective mitigation of any threat to archaeological features and sites. The use of bales, commonly employed in other upland ecosystems, was found to be problematic. Instead, 'leaky dams' or wood and peat combination dams were used, which are both more efficient at reducing and diverting the flow, and longer lasting than bale dams. Finally, an average restoration cost (£306 ha(-1)) for Exmoor, below the median national value across the whole of the UK, demonstrates the cost-effectiveness of these techniques. However, local differences in peat depth and ditch characteristics (i.e. length, depth and width) between sites affect both the feasibility and the cost of restoration. Overall, the restoration of shallow peatlands is shown to be technically viable; this paper provides a template for such process

  13. Temporal variations in the stable carbon isotopic composition of methane emitted from Minnesota peatlands

    NASA Astrophysics Data System (ADS)

    Kelly, Cheryl A.; Dise, Nancy B.; Martens, Christopher S.

    1992-09-01

    The stable carbon isotopic composition of methane (δ13C) emitted from two peatland sites in the Marcell Experimental Forest in northern Minnesota was investigated during the snow-free season of 1989-1990. A seasonal range in δ13C values of 13‰ was seen for a forested bog with heavier (13C enriched) methane emitted during the wanner summer months. This shift was correlated with water table level suggesting control by microbial oxidation. Methane from a nearby poor fen transitional to bog dominated by Carex oligosperma showed a similar temporal trend but with a much smaller range of 5‰ during the same time period and with no water table level correlation. The methane emitted from the fen was consistently heavier than that emitted by the bog.

  14. Effects of winter temperature and summer drought on net ecosystem exchange of CO2 in a temperate peatland

    NASA Astrophysics Data System (ADS)

    Helfter, Carole; Campbell, Claire; Dinsmore, Kerry; Drewer, Julia; Coyle, Mhairi; Anderson, Margaret; Skiba, Ute; Nemitz, Eiko; Billett, Michael; Sutton, Mark

    2014-05-01

    Northern peatlands are one of the most important global sinks of atmospheric carbon dioxide (CO2); their ability to sequester C is a natural feedback mechanism controlled by climatic variables such as precipitation, temperature, length of growing season and period of snow cover. In the UK it has been predicted that peatlands could become a net source of carbon in response to climate change with climate models predicting a rise in global temperature of ca. 3oC between 1961-1990 and 2100. Land-atmosphere exchange of CO2in peatlands exhibits marked seasonal and inter-annual variations, which have significant short- and long-term effects on carbon sink strength. Net ecosystem exchange (NEE) of CO2 has been measured continuously by eddy-covariance (EC) at Auchencorth Moss (55° 47'32 N, 3° 14'35 W, 267 m a.s.l.), a temperate peatland in central Scotland, since 2002. Auchencorth Moss is a low-lying, ombrotrophic peatland situated ca. 20 km south-west of Edinburgh. Peat depth ranges from 5 m and the site has a mean annual precipitation of 1155 mm. The vegetation present within the flux measurement footprint comprises mixed grass species, heather and substantial areas of moss species (Sphagnum spp. and Polytrichum spp.). The EC system consists of a LiCOR 7000 closed-path infrared gas analyser for the simultaneous measurement of CO2 and water vapour and of a Gill Windmaster Pro ultrasonic anemometer. Over the 10 year period, the site was a consistent yet variable sink of CO2 ranging from -34.1 to -135.9 g CO2-C m-2 yr-1 (mean of -69.1 ± 33.6 g CO2-C m-2 yr-1). Inter-annual variability in NEE was positively correlated to the length of the growing seasons and mean winter air temperature explained 93% of the variability in summertime sink strength, indicating a phenological memory-effect. Plant development and productivity were stunted by colder winters causing a net reduction in the annual carbon sink strength of this peatland where autotrophic processes are thought to be

  15. Reconstruction of the Last Outburst Flood of Glacial Lake Agassiz-Ojibway in Hudson Bay and Hudson Strait

    NASA Astrophysics Data System (ADS)

    Lajeunesse, P.; St-Onge, G.

    2007-12-01

    Hudson Bay and Hudson Strait were the sites of a rapid deglaciation that culminated in the catastrophic drainage of proglacial Lake Agassiz-Ojibway into the North Atlantic at ~8.47 cal kyr BP. It has previously been suggested that this sudden outburst of freshwater may have weakened the thermohaline circulation and triggered the 8200 cal BP cold event recorded in Greenland ice cores. Evidence for the outburst flood included geomorphic features observed on the seafloor of southern Hudson Bay and the identification of a centimeter to decimeter- thick hematite-rich red layer present in Hudson Strait sediment cores. However, unequivocal evidence is still lacking in order to define the way the lake drained (i.e., either by a breach through the ice-dam, a supraglacial spillover or a subglacial flood), whether it drained by one or more pulses and the location of the northward flood routes toward Hudson Bay. In this paper, we present new seafloor images and sediment cores collected onboard the CCGS Amundsen in Hudson Bay and Hudson Strait in 2004 and 2005 that shed light on the dynamics of the final drainage of the ice-dammed lakes. We found that this sudden outburst flood combined with subsequent currents displaced icebergs back-and-forth in a former calving bay to produce preferentially oriented arc-shaped scours on the seafloor. In addition, fields of giant sandwaves were identified in southern Hudson Bay in areas unaffected by arcuate iceberg scours, suggesting that they were protected from iceberg scouring by overlying glacier ice during the lake drainage event. The subglacial origin of the widely distributed sandwaves and the occurrence of many submarine channels lead us to propose that the drainage of Lake Agassiz-Ojibway took place by a buoyant lifting of the rapidly thinning LIS along many subglacial routes that spread over the entire southern Hudson Bay region. We also reveal that the red bed contains two layers deposited by hyperpycnal flows (hyperpycnites

  16. Towards a Global High Resolution Peatland Map in 2020

    NASA Astrophysics Data System (ADS)

    Barthelmes, Alexandra; Barthelmes, Karen-Doreen; Joosten, Hans; Dommain, Rene; Margalef, Olga

    2015-04-01

    Some 3% of land area on planet Earth (approx. 4 million km2) is covered by peatlands. About 10% (~ 0.3 % of the land area) are drained and responsible for a disproportional 5 % of the global anthropogenic CO2 emissions (Victoria et al., 2012). Additionally, peatland drainage and degradation lead to land subsidence, soil degradation, water pollution, and enhanced susceptibility to fire (Holden et al., 2004; Joosten et al., 2012). The global importance of peatlands for carbon storage and climate change mitigation has currently been recognized in international policy - since 2008 organic soils are subject of discussion in the UN Framework Convention on Climate Change (UNFCCC) (Joosten, 2011). In May 2013 the European Parliament decided that the global post 2020 climate agreement should include the obligation to report emissions and removals from peatland drainage and rewetting. Implementation of such program, however, necessitates the rapid availability of reliable, comprehensive, high resolution, spatially explicit data on the extent and status of peatlands. For many reporting countries this requires an innovation in peatland mapping, i.e. the better and integrative use of novel, but already available methods and technologies. We developed an approach that links various science networks, methodologies and data bases, including those of peatland/landscape ecology for understanding where and how peatlands may occur, those of remote sensing for identifying possible locations, and those of pedology (legacy soil maps) and (palaeo-)ecology for ground truthing. Such integration of old field data, specialized knowledge, and modern RS and GIS technologies enables acquiring a rapid, comprehensive, detailed and rather reliable overview, even on a continental scale. We illustrate this approach with a high resolution overview of peatland distribution, area, status and greenhouse gas fluxes e.g. for the East African countries Rwanda, Burundi, Uganda and Zambia. Furthermore, we

  17. Towards a Global High Resolution Peatland Map in 2020

    NASA Astrophysics Data System (ADS)

    Barthelmes, Alexandra; Barthelmes, Karen-Doreen; Dommain, Rene; Margalef, Olga; Joosten, Hans

    2014-05-01

    Some 3% of land area on planet Earth (approx. 4 million km2) is covered by peatlands. About 10% (~ 0.3 % of the land area) are drained and responsible for a disproportional 5 % of the global anthropogenic CO2 emissions (Victoria et al., 2012). Additionally, peatland drainage and degradation lead to land subsidence, soil degradation, water pollution, and enhanced susceptibility to fire (Holden et al., 2004; Joosten et al., 2012). The global importance of peatlands for carbon storage and climate change mitigation has only recently been recognized in international policy - only since 2008 organic soils are subject of discussion in the UN Framework Convention on Climate Change (UNFCCC) (Joosten, 2011). In May 2013 the European Parliament decided that the global post 2020 climate agreement should include the obligation to report emissions and removals from peatland drainage and rewetting. Implementation of such program, however, necessitates the rapid availability of reliable, comprehensive, high resolution, spatially explicit data on the extent and status of peatlands. For many reporting countries this requires an innovation in peatland mapping, i.e. the better and integrative use of novel, but already available methods and technologies. We developed an approach that links various science networks, methodologies and data bases, including those of peatland/landscape ecology for understanding where and how peatlands may occur, those of remote sensing for identifying possible locations, and those of pedology (legacy soil maps) and (palaeo-)ecology for ground truthing. Such integration of old field data, specialized knowledge, and modern RS and GIS technologies enables acquiring a rapid, comprehensive, detailed and rather reliable overview, even on a continental scale. We illustrate this approach with a high resolution overview of peatland distribution, area, status and greenhouse gas fluxes for East Africa (including the Horn of Africa, the African Great Lakes region and

  18. Quality of runoff from Minnesota peatlands. I. A characterization

    SciTech Connect

    Clausen, J.C.; Brooks, K.N.

    1983-10-01

    The likelihood of expanded use of Minnesota's 3 million hectares of peatlands prompted the state to initiate a hydrologic study to characterize these groundwater-linked systems. Determining the quality of stream flow from these peatlands was an integral part of the study. Peatlands could be differentiated either on the basis of stream flow quality or on soil-vegetation characteristics. The quality of stream flow from 45 undisturbed peatlands was characterized by collecting samples five times in 1979-1980 and analyzing them for 27 water quality characteristics. Runoff pH, specific conductance, alkalinity, calcium, and magnesium were used to classify the peatlands as bog, transition, or fen. Bog runoff was lower (..cap alpha.. = 0.05) in pH, calcium, sodium, manganese, and ammonia nitrogen than fen runoff, but was higher in acidity, color, aluminum, humic and fulvic acid, and chemical oxygen demand than fen runoff. Bogs had more fibric peat of a lower pH than fens; fens exhibited tall woody shrubs which were virtually absent on bogs. 5 references, 3 figures, 3 tables.

  19. Nelson's big horn sheep (Ovis canadensis nelsoni) trample Agassiz's desert tortoise (Gopherus agassizii) burrow at a California wind energy facility

    USGS Publications Warehouse

    Agha, Mickey; Delaney, David F.; Lovich, Jeffrey E.; Briggs, Jessica; Austin, Meaghan; Price, Steven J.

    2015-01-01

    Research on interactions between Agassiz's desert tortoises (Gopherus agassizii) and ungulates has focused exclusively on the effects of livestock grazing on tortoises and their habitat (Oldemeyer, 1994). For example, during a 1980 study in San Bernardino County, California, 164 desert tortoise burrows were assessed for vulnerability to trampling by domestic sheep (Ovis aries). Herds of grazing sheep damaged 10% and destroyed 4% of the burrows (Nicholson and Humphreys 1981). In addition, a juvenile desert tortoise was trapped and an adult male was blocked from entering a burrow due to trampling by domestic sheep. Another study found that domestic cattle (Bos taurus) trampled active desert tortoise burrows and vegetation surrounding burrows (Avery and Neibergs 1997). Trampling also has negative impacts on diversity of vegetation and intershrub soil crusts in the desert southwest (Webb and Stielstra 1979). Trampling of important food plants and overgrazing has the potential to create competition between desert tortoises and domestic livestock (Berry 1978; Coombs 1979; Webb and Stielstra 1979).

  20. Can oxygen stable isotopes be used to track precipitation moisture source in vascular plant-dominated peatlands?

    NASA Astrophysics Data System (ADS)

    Amesbury, Matthew J.; Charman, Dan J.; Newnham, Rewi M.; Loader, Neil J.; Goodrich, Jordan; Royles, Jessica; Campbell, David I.; Keller, Elizabeth D.; Baisden, W. Troy; Roland, Thomas P.; Gallego-Sala, Angela V.

    2015-11-01

    Variations in the isotopic composition of precipitation are determined by fractionation processes which occur during temperature- and humidity-dependent phase changes associated with evaporation and condensation. Oxygen stable isotope ratios have therefore been frequently used as a source of palaeoclimate data from a variety of proxy archives, which integrate this signal over time. Applications from ombrotrophic peatlands, where the source water used in cellulose synthesis is derived solely from precipitation, have been mostly limited to Northern Hemisphere Sphagnum-dominated bogs, with few in the Southern Hemisphere or in peatlands dominated by vascular plants. New Zealand (NZ) provides an ideal location to undertake empirical research into oxygen isotope fractionation in vascular peatlands because single taxon analysis can be easily carried out, in particular using the preserved root matrix of the restionaceous wire rush (Empodisma spp.) that forms deep Holocene peat deposits throughout the country. Furthermore, large gradients are observed in the mean isotopic composition of precipitation across NZ, caused primarily by the relative influence of different climate modes. Here, we test whether δ18O of Empodisma α-cellulose from ombrotrophic restiad peatlands in NZ can provide a methodology for developing palaeoclimate records of past precipitation δ18O. Surface plant, water and precipitation samples were taken over spatial (six sites spanning >10° latitude) and temporal (monthly measurements over one year) gradients. A link between the isotopic composition of root-associated water, the most likely source water for plant growth, and precipitation in both datasets was found. Back-trajectory modelling of precipitation moisture source for rain days prior to sampling showed clear seasonality in the temporal data that was reflected in root-associated water. The link between source water and plant cellulose was less clear, although mechanistic modelling predicted mean

  1. Reconstruction of a paleolandscape in the Hunzebasin (Northern Netherlands)

    NASA Astrophysics Data System (ADS)

    Zomer, Jeroen; Spek, Theo

    2013-04-01

    In recent decades, significant changes have occurred in ways of thinking about the genesis of the coastal areas of Northwest Europe. In the study of the Holocene coastal genesis of Northwest Europe, a new diversified model has been developed. While the old model was based on a synchronized and coherent development of the entire Northwest European coast, the new model focuses attention on domain-specific natural processes. At the same time, the interaction between man and nature in the coastal zone is put into another perspective. The idea that man unilaterally conformed to the natural influence of the sea has gradually been replaced by a more dynamic and co-adaptive model. These developments in ways of thinking are also important for the research of medieval reclamation of peatlands in the coastal area in the Northern Netherlands (present provinces of Friesland and Groningen). This research has long been overshadowed by theories and research concerning other areas, particularly the Western Netherlands. The classic uniform reclamation model, which has until now been applied to the peatland reclamations in the Northern Netherlands, needs revision. In my PhD research, I develop a new diversified reclamation model based on interdisciplinary research into the natural landscape and the reclamation history. The study focusses on the medieval peatland reclamations in the Hunze basin. The Hunze basin is a deeply eroded Pleistocene valley filled up with Holocene sediments in the Northern Netherlands, where in the late Holocene a tidal system has developed with its own domain-specific characteristics. This paper, based on empirical research, covers the reconstruction of the 'natural' early medieval coastal peatlands in the Hunze basin. From previous research, it is known that the complete study area was covered with a layer of peat. In these studies, however, no statements are made about the peat landscape itself or the vegetation. At present a major part of the peatlands has

  2. Hydrology and Geostatistics of a Vermont, USA Kettlehole Peatland

    NASA Astrophysics Data System (ADS)

    Mouser, Paula J.; Hession, W. Cully; Rizzo, Donna M.; Gotelli, Nicholas J.

    2005-01-01

    The ability to predict the response of peatland ecosystems to hydrologic changes is imperative for successful conservation and remediation efforts. We studied a 1.25-ha Vermont kettlehole bog for one year (September 2001-October 2002) to identify hydrologic controls, temporal and spatial variability in flow regimes, and to link hydrologic processes to density of the carnivorous plant ( Sarracenia purpurea), an ombrotrophic bog specialist. Using a spatial array of nested piezometers, we measured surface and subsurface flow in shallow peat and surrounding mineral soil. Our unique sampling array was based on a repeated measures factorial design with: (1) incremental distances from a central kettlehole pond; (2) equal distances between piezometers; and (3) at three depths from the peat surface. Local flow patterns in the peat were controlled by snowpack storage during winter and spring months and by evapotranspiration and pond water elevation during summer and fall months. Hydraulic head values showed a local reversal within the peat during spring months which was reflected in higher chemical constituent concentrations in these wells. On a regional scale, higher permeable soils diverted groundwater beneath the peatland to a nearby wetland complex. Horizontal water gradient magnitudes were larger in zones where the peatland was perched above regional groundwater and smaller in zones where a hydraulic connection existed between the peatland and the regional groundwater. The density of pitcher plants ( S. purpurea) is strongly correlated to the distance from a central pond, [Fe 3+], [Na +], [Cl -], and [SO42-]. The pH, conductivity, and [Ca 2+] had significant effects of depth and time with horizontal distance correlations between 20 and 26 m. The pH samples had temporal correlations between 27 and 79 days. The link between pitcher plants and ion chemistry; significant effects of peatland chemistry on distance, depth, and time; and spatial and temporal correlations are

  3. Hydrogeological controls on post-fire moss recovery in peatlands

    NASA Astrophysics Data System (ADS)

    Lukenbach, M. C.; Devito, K. J.; Kettridge, N.; Petrone, R. M.; Waddington, J. M.

    2015-11-01

    Wildfire is the largest disturbance affecting boreal peatlands, however, little is known about the controls on post-fire peatland vegetation recovery. While small-scale variation in burn severity can reduce post-fire moss water availability, high water table (WT) positions following wildfire are also critical to enable the re-establishment of keystone peatland mosses (i.e. Sphagnum). Thus, post-fire moss water availability is also likely a function of landscape-scale controls on peatland WT dynamics, specifically, connectivity to groundwater flow systems (i.e. hydrogeological setting). For this reason, we assessed the interacting controls of hydrogeological setting and burn severity on post-fire moss water availability in three burned, Sphagnum-dominated peatlands in Alberta's Boreal Plains. At all sites, variation in burn severity resulted in a dichotomy between post-fire surface covers that: (1) exhibited low water availability, regardless of WT position, and had minimal (<5%) moss re-establishment (i.e. lightly burned feather mosses and severely burned Sphagnum fuscum) or (2) exhibited high water availability, depending on WT position, and had substantial (>50%) moss re-establishment (i.e. lightly burned S. fuscum and where depth of burn was >0.05 m). Notably, hydrogeological setting influenced the spatial coverage of these post-fire surface covers by influencing pre-fire WTs and stand characteristics (e.g., shading). Because feather moss cover is controlled by tree shading, lightly burned feather mosses were ubiquitous (>25%) in drier peatlands (deeper pre-fire WTs) that were densely treed and had little connection to large groundwater flow systems. Moreover, hydrogeological setting also controlled post-fire WT positions, thereby affecting moss re-establishment in post-fire surface covers that were dependent on WT position (e.g., lightly burned S. fuscum). Accordingly, higher recolonization rates were observed in a peatland located in a groundwater flow through

  4. Hydrogeological controls on post-fire moss recovery in peatlands

    NASA Astrophysics Data System (ADS)

    Lukenbach, Max; Devito, Kevin; Kettridge, Nicholas; Petrone, Richard; Waddington, James

    2015-04-01

    Wildfire is the largest disturbance affecting peatlands, however, little is known about the spatiotemporal variability of post-fire recovery in these ecosystems. High water table (WT) positions after wildfire are critical to limit atmospheric carbon losses and enable the re-establishment of keystone peatland mosses (i.e. Sphagnum). While small-scale variation in burn severity can reduce capillary flow from the WT and lead to a dry surface after fire, steep WT declines can also limit post-fire moss water availability. As such, post-fire moss water availability is also a function of large-scale controls on peatland WT dynamics, specifically, connectivity to groundwater flow systems (i.e. hydrogeological setting). For this reason, we assessed the interacting controls of hydrogeological setting and burn severity on post-fire moss water availability by measuring peatland WTs, soil tension (Ψ) and surface volumetric moisture content (θ) in three burned, Sphagnum-dominated peatlands located in different hydrogeological settings for three years following wildfire. The effect of burn severity on post-fire moss water availability did not vary with hydrogeological setting, however, the spatial coverage of high and low burn severity did vary between peatlands located in different hydrogeological settings due to its influence on pre-fire fuel loads and species cover. Locations covered by S. fuscum prior to fire exhibited decreasing post-fire water availability with increasing burn severity. In contrast, the lowest water availability (Ψ > 400 cm, θ < 0.02) was observed in feather mosses that underwent low burn severity (residual branches identifiable). Where depth of burn was > 0.05 m (high burn severity) and pre-fire species were not identifiable, water availability was highest (Ψ < 90 cm). Where burn severity did not limit water availability through a reduction of capillary flow, depth to WT (and therefore hydrogeological setting) played a large role in affecting post

  5. Changes in the Bathymetry and Volume of Glacial Lake Agassiz Between 11,000 and 9300 14C yr B.P.

    NASA Astrophysics Data System (ADS)

    Leverington, David W.; Mann, Jason D.; Teller, James T.

    2000-09-01

    The volume and surface area of glacial Lake Agassiz varied considerably during its 4000-year history. Computer models for seven stages of Lake Agassiz were used to quantify these variations over the lake's early history, between about 11,000 and 9300 14C yr B.P. (ca. 13,000 to 10,300 cal yr B.P.). Just after formation of the Herman strandlines (ca. 11,000 14C yr B.P.), the volume of Lake Agassiz appears to have decreased by >85% as a consequence of the abrupt rerouting of overflow to its eastern outlet from its southward routing into the Mississippi River basin. This drainage released about 9500 km3 of water into the North Atlantic Ocean via the Great Lakes and Gulf of St. Lawrence. Following closure of this eastern routing of overflow, the lake reached its maximum size at about 9400 14C yr B.P. with an area of >260,000 km2 and a volume of >22,700 km3. A second major reduction in volume occurred shortly after that, when its volume decreased >10% following the opening of the Kaiashk outlet to the east into the Great Lakes, and 2500-7000 km3 of water was released into the North Atlantic Ocean. These discharges may have affected ocean circulation and North Atlantic Deep Water production.

  6. Characterizing dissolved organic carbon concentrations and export in a boreal forest-peatland landscape under the influence of rapidly degrading discontinuous permafrost

    NASA Astrophysics Data System (ADS)

    Hanisch, J.; Connon, R.; Templeton, M.; Quinton, W. L.; Olefeldt, D.; Moore, T. R.; Roulet, N. T.; Sonnentag, O.

    2014-12-01

    Our current understanding of peatland energy, water and carbon (C) cycles implies that northern peatlands are vulnerable to projected climate change, and that the perturbation of these cycles might cause a strong positive or negative net feedback to the climate system. About one third of Canada's northern peatlands contain contain perennialy frozen ground (permafrost). Boreal forest-peatland ecosystems in the discontinuous permafrost zone (50-90% of frozen ground) are especially vulnerable to rising temperatures as permafrost is ice-rich, relatively warm and thin, and thus susceptible to complete disappearance causing ground surface subsidence and a decline in forest cover in response to water-logging. Several recent studies have substantially improved our understanding of northern peatland's role in the climate system by quantifying their net ecosystem C balance which includes atmospheric and aqueous C fluxes generally dominated by the export of dissolved organic C (DOC). We characterize seasonal and diurnal variations in DOC export from five catchments (0.02-0.05 km2) at Scotty Creek, a 152 km2-watershed under the influence of rapidly degrading and disappearing discontinuous permafrost near Fort Simpson, Northwest Territories, Canada. The five catchments are characterized by different fractions of forested peat plateaus with permafrost (38-73%) and permafrost-free collapse bogs (27-62%). Dissolved organic carbon concentrations at Scotty Creek appear to be higher in catchments where the percentage of peat plateaus is higher compared to bogs, independent of catchment size. Average DOC concentration for catchments with a lower percentage of peat plateaus is lower (~43 mg/l) than for those with a higher percentage of plateaus (~60 mg/l). These preliminary results suggest that lateral C losses from this rapidly changing landscape are at least partly controlled by the peat plateau-bog ratio. Over the year, DOC export from the five catchments is limited to around a week

  7. An Integration of a GIS with Peatland Management

    NASA Technical Reports Server (NTRS)

    Hoshal, J. C.; Johnson, R. L.

    1982-01-01

    The complexities of peatland management in Minnesota and the use of a geographic information system, the Minnesota Land Management Information System (MLMIS) in the management process are examined. General information on the nature of peat and it quantity and distribution in Minnesota is also presented.

  8. Russian boreal peatlands dominate the natural European methane budget

    NASA Astrophysics Data System (ADS)

    Schneider, Julia; Jungkunst, Hermann F.; Wolf, Ulrike; Schreiber, Peter; Gažovič, Michal; Miglovets, Mikhail; Mikhaylov, Oleg; Grunwald, Dennis; Erasmi, Stefan; Wilmking, Martin; Kutzbach, Lars

    2016-01-01

    About 60% of the European wetlands are located in the European part of Russia. Nevertheless, data on methane emissions from wetlands of that area are absent. Here we present results of methane emission measurements for two climatically different years from a boreal peatland complex in European Russia. Winter fluxes were well within the range of what has been reported for the peatlands of other boreal regions before, but summer fluxes greatly exceeded the average range of 5-80 mg CH4 m-2 d-1 for the circumpolar boreal zone. Half of the measured fluxes ranged between 150 and 450 mg CH4 m-2 d-1. Extrapolation of our data to the whole boreal zone of European Russia shows that theses emissions could amount to up to 2.7 ± 1.1 Tg CH4 a-1, corresponding to 69% of the annual emissions from European wetlands or 33% of the total annual natural European methane emission. In 2008, climatic conditions corresponded to the long term mean, whereas the summer of 2011 was warmer and noticeably drier. Counterintuitively, these conditions led to even higher CH4 emissions, with peaks up to two times higher than the values measured in 2008. As Russian peatlands dominate the areal extend of wetlands in Europe and are characterized by very high methane fluxes to the atmosphere, it is evident, that sound European methane budgeting will only be achieved with more insight into Russian peatlands.

  9. CO2 fluxes at northern fens and bogs have opposite responses to inter-annual fluctuations in water table

    NASA Astrophysics Data System (ADS)

    Sulman, Benjamin N.; Desai, Ankur R.; Saliendra, Nicanor Z.; Lafleur, Peter M.; Flanagan, Lawrence B.; Sonnentag, Oliver; Mackay, D. Scott; Barr, Alan G.; van der Kamp, Garth

    2010-10-01

    This study compares eddy-covariance measurements of carbon dioxide fluxes at six northern temperate and boreal peatland sites in Canada and the northern United States of America, representing both bogs and fens. The two peatland types had opposite responses of gross ecosystem photosynthesis (GEP) and ecosystem respiration (ER) to inter-annual fluctuations in water table level. At fens, wetter conditions were correlated with lower GEP and ER, while at bogs wetter conditions were correlated with higher GEP and ER. We hypothesize that these contrasting responses are due to differences in the relative contributions of vascular plants and mosses. The coherence of our results between sites representing a range of average environmental conditions indicates ecosystem-scale differences in resilience to hydrological changes that should be taken into account when considering the future of peatland ecosystem services such as carbon sequestration under changing environmental conditions.

  10. Production of Excess CO2 relative to methane in peatlands: a new H2 sink

    NASA Astrophysics Data System (ADS)

    Wilson, R.; Woodcroft, B. J.; Varner, R. K.; Tyson, G. W.; Tfaily, M. M.; Sebestyen, S.; Saleska, S. R.; Rogers, K.; Rich, V. I.; McFarlane, K. J.; Kostka, J. E.; Kolka, R. K.; Keller, J.; Iversen, C. M.; Hodgkins, S. B.; Hanson, P. J.; Guilderson, T. P.; Griffiths, N.; de La Cruz, F.; Crill, P. M.; Chanton, J.; Bridgham, S. D.; Barlaz, M.

    2015-12-01

    Methane is generated as the end product of anaerobic organic matter degradation following a series of reaction pathways including fermentation and syntrophy. Along with acetate and CO2, syntrophic reactions generate H2 and are only thermodynamically feasible when coupled to an exothermic reaction that consumes H2. The usual model of organic matter degradation in peatlands has assumed that methanogenesis is that exothermic H2-consuming reaction. If correct, this paradigm should ultimately result in equimolar production of CO2 and methane from the degradation of the model organic compound cellulose: i.e. C6H12O6 à 3CO2 + 3CH4. However, dissolved gas measurement and modeling results from field and incubation experiments spanning peatlands across the northern hemisphere have failed to demonstrate equimolar production of CO2 and methane. Instead, in a flagrant violation of thermodynamics, these studies show a large bias favoring CO2 production over methane generation. In this talk, we will use an array of complementary analytical techniques including FT-IR, cellulose and lignin measurements, 13C-NMR, fluorescence spectroscopy, and ultra-high resolution mass spectrometry to describe organic matter degradation within a peat column and identify the important degradation mechanisms. Hydrogenation was the most common transformation observed in the ultra-high resolution mass spectrometry data. From these results we propose a new mechanism for consuming H2 generated during CO2 production, without concomitant methane formation, consistent with observed high CO2/CH4 ratios. While homoacetogenesis is a known sink for H2 in these systems, this process also consumes CO2 and therefore does not explain the excess CO2 measured in field and incubation samples. Not only does the newly proposed mechanism consume H2 without generating methane, but it also yields enough energy to balance the coupled syntrophic reactions, thereby restoring thermodynamic order. Schematic of organic matter

  11. Impacts of peatland forestation on regional climate conditions in Finland

    NASA Astrophysics Data System (ADS)

    Gao, Yao; Markkanen, Tiina; Backman, Leif; Henttonen, Helena M.; Pietikäinen, Joni-Pekka; Laaksonen, Ari

    2014-05-01

    Climate response to anthropogenic land cover change happens more locally and occurs on a shorter time scale than the global warming due to increased GHGs. Over the second half of last Century, peatlands were vastly drained in Finland to stimulate forest growth for timber production. In this study, we investigate the biophysical effects of peatland forestation on near-surface climate conditions in Finland. For this, the regional climate model REMO, developed in Max Plank Institute (currently in Climate Service Center, Germany), provides an effective way. Two sets of 15-year climate simulations were done by REMO, using the historic (1920s; The 1st Finnish National Forest Inventory) and present-day (2000s; the 10th Finnish National Forest Inventory) land cover maps, respectively. The simulated surface air temperature and precipitation were then analyzed. In the most intensive peatland forestation area in Finland, the differences in monthly averaged daily mean surface air temperature show a warming effect around 0.2 to 0.3 K in February and March and reach to 0.5 K in April, whereas a slight cooling effect, less than 0.2 K, is found from May till October. Consequently, the selected snow clearance dates in model gridboxes over that area are advanced 0.5 to 4 days in the mean of 15 years. The monthly averaged precipitation only shows small differences, less than 10 mm/month, in a varied pattern in Finland from April to September. Furthermore, a more detailed analysis was conducted on the peatland forestation area with a 23% decrease in peatland and a 15% increase in forest types. 11 day running means of simulated temperature and energy balance terms, as well as snow depth were averaged over 15 years. Results show a positive feedback induced by peatland forestation between the surface air temperature and snow depth in snow melting period. This is because the warmer temperature caused by lower surface albedo due to more forest in snow cover period leads to a quicker and

  12. Stimulation of both photosynthesis and respiration in response to warmer and drier conditions in a boreal peatland ecosystem

    NASA Astrophysics Data System (ADS)

    Flanagan, L. B.; Syed, K. H.

    2010-12-01

    Peatland ecosystems have been consistent carbon sinks for millennia, but it has been predicted that exposure to warmer temperatures and drier conditions associated with climate change will shift the balance between ecosystem photosynthesis and respiration providing a positive feedback to atmospheric CO2 concentration. Our main objective was to determine the sensitivity of ecosystem photosynthesis, respiration and net ecosystem production (NEP) measured by eddy covariance, to variation in temperature and water table depth associated with inter-annual shifts in weather during 2004-2009. Our study was conducted in a moderately-rich treed fen, the most abundant peatland type in western Canada, in a region (northern Alberta) where peatland ecosystems are a significant landscape component. During the study, the average growing season (May-October) water depth declined approximately 38 cm, and temperature (expressed as cumulative growing degree days (GDD, March-October)) varied approximately 370 GDD. Contrary to previous predictions, both ecosystem photosynthesis and respiration showed similar increases in response to warmer and drier conditions. The ecosystem remained a strong net sink for CO2 with an average NEP (± SD) of 189 ± 47 g C m-2 year-1. The current net CO2 uptake rates were much higher than carbon accumulation in peat determined from analyses of the relationship between peat age and cumulative carbon stock. The balance between carbon addition to, and total loss from, the top 0-30 cm depth (peat age range 0-70 years) of shallow peat cores averaged 43 ± 12 g C m-2 year-1. The apparent long-term average rate of net carbon accumulation in basal peat samples from deep cores was 19-24 g C m-2 year-1. The difference between current rates of carbon uptake and historical rates of peat accumulation likely resulted from vegetation succession (increase in tree productivity), and improving environmental conditions that have stimulated ecosystem photosynthesis more than

  13. Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence

    NASA Astrophysics Data System (ADS)

    Johnston, Carmel E.; Ewing, Stephanie A.; Harden, Jennifer W.; Varner, Ruth K.; Wickland, Kimberly P.; Koch, Joshua C.; Fuller, Christopher C.; Manies, Kristen; Torre Jorgenson, M.

    2014-08-01

    Permafrost soils store over half of global soil carbon (C), and northern frozen peatlands store about 10% of global permafrost C. With thaw, inundation of high latitude lowland peatlands typically increases the surface-atmosphere flux of methane (CH4), a potent greenhouse gas. To examine the effects of lowland permafrost thaw over millennial timescales, we measured carbon dioxide (CO2) and CH4 exchange along sites that constitute a ˜1000 yr thaw chronosequence of thermokarst collapse bogs and adjacent fen locations at Innoko Flats Wildlife Refuge in western Alaska. Peak CH4 exchange in July (123 ± 71 mg CH4-C m-2 d-1) was observed in features that have been thawed for 30 to 70 (<100) yr, where soils were warmer than at more recently thawed sites (14 to 21 yr; emitting 1.37 ± 0.67 mg CH4-C m-2 d-1 in July) and had shallower water tables than at older sites (200 to 1400 yr; emitting 6.55 ± 2.23 mg CH4-C m-2 d-1 in July). Carbon lost via CH4 efflux during the growing season at these intermediate age sites was 8% of uptake by net ecosystem exchange. Our results provide evidence that CH4 emissions following lowland permafrost thaw are enhanced over decadal time scales, but limited over millennia. Over larger spatial scales, adjacent fen systems may contribute sustained CH4 emission, CO2 uptake, and DOC export. We argue that over timescales of decades to centuries, thaw features in high-latitude lowland peatlands, particularly those developed on poorly drained mineral substrates, are a key locus of elevated CH4 emission to the atmosphere that must be considered for a complete understanding of high latitude CH4 dynamics.

  14. Using Satellite Measurements of Surface Soil Moisture to Improve Estimates of CO2 and CH4 from Peatlands

    NASA Astrophysics Data System (ADS)

    MacBean, N.; Disney, M.; Gomez-Dans, J.; Lewis, P.; Ineson, P.

    2010-12-01

    Peatlands are important stores of carbon through the partial decomposition of organic matter. However peatlands not only sequester CO2 but they are the main natural source of methane (CH4) due to anaerobic microbial activity under waterlogged conditions. Northern wetlands contribute about 35TgCH4yr-1 [1]. The uncertainty on this estimate is large (from 1mgCH4 m-2 y-1 to 2200mgCH4 m-2 y-1), therefore there is a need to better quantify CH4 emissions and their role in the net carbon balance of peatlands. A correct representation of the hydrology of the system is necessary for modelling CH4 flux as the water table depth controls the area where methanogenic bacteria are active. One of the key variables in the calculation of water table depth is the soil moisture. Soil moisture also affects the decomposition rates of carbon in the soil and influences the water and energy fluxes at the land surface - atmosphere boundary. Microwave measurements of surface soil moisture from satellites can theoretically be used to improve estimates predicted by models. Results from an Observing System Simulation Experiment (OSSE), designed to investigate how observations from satellites may be able to constrain modelled carbon fluxes, are presented. An adapted version of the Carnegie-Ames-Stanford Approach (CASA) model [2] is used that includes a representation of methane dynamics [3]. Synthetic satellite observations of soil moisture are used to update model estimates using a Metropolis Hastings Markov Chain Monte Carlo (MCMC) approach. The effect of temporal frequency and spacing, and precision of observations, is examined with a view to establishing the set of observations that would make a significant improvement in model uncertainty. The results are compared with the system characteristics of existing satellite soil moisture measurements. We believe this is the first attempt to assimilate surface soil moisture into an ecosystem model that includes a full representation of CH4 flux.

  15. Controls on bacterial and archaeal community structure and greenhouse gas production in natural, mined, and restored Canadian peatlands

    PubMed Central

    Basiliko, Nathan; Henry, Kevin; Gupta, Varun; Moore, Tim R.; Driscoll, Brian T.; Dunfield, Peter F.

    2013-01-01

    Northern peatlands are important global C reservoirs, largely because of their slow rates of microbial C mineralization. Particularly in sites that are heavily influenced by anthropogenic disturbances, there is scant information about microbial ecology and whether or not microbial community structure influences greenhouse gas production. This work characterized communities of bacteria and archaea using terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of 16S rRNA and functional genes across eight natural, mined, or restored peatlands in two locations in eastern Canada. Correlations were explored among chemical properties of peat, bacterial and archaeal community structure, and carbon dioxide (CO2) and methane (CH4) production rates under oxic and anoxic conditions. Bacteria and archaea similar to those found in other peat soil environments were detected. In contrast to other reports, methanogen diversity was low in our study, with only 2 groups of known or suspected methanogens. Although mining and restoration affected substrate availability and microbial activity, these land-uses did not consistently affect bacterial or archaeal community composition. In fact, larger differences were observed between the two locations and between oxic and anoxic peat samples than between natural, mined, and restored sites, with anoxic samples characterized by less detectable bacterial diversity and stronger dominance by members of the phylum Acidobacteria. There were also no apparent strong linkages between prokaryote community structure and CH4 or CO2 production, suggesting that different organisms exhibit functional redundancy and/or that the same taxa function at very different rates when exposed to different peat substrates. In contrast to other earlier work focusing on fungal communities across similar mined and restored peatlands, bacterial and archaeal communities appeared to be more resistant or resilient to peat substrate changes brought

  16. Variations in Biogenic Gas Content Profiles Along a Crest-Lawn-Fen Transect of an Ombrotrophic Minnesota Peatland from Non-Invasive Geophysical Measurements

    NASA Astrophysics Data System (ADS)

    Parsekian, A.; Slater, L. D.; Comas, X.; Glaser, P. H.

    2009-12-01

    Northern peatlands contain free-phase carbon gas biogenically produced below the surface under anaerobic conditions. Quantification of the spatial variability of free-phase gas is needed to improve understanding of carbon gas dynamics in peatlands. In an effort to better understand the spatial variability in free-phase gas accumulations between different peat landforms, we completed a series of ground-penetrating radar (GPR) surveys across a crest - lawn - fen transition in a large peatland in Minnesota, USA. Common offset profiles were employed to detect changes in the peat stratigraphy and basal mineral reflector, while common mid-point (CMP) surveys were utilized to estimate gas content within the peat at regular intervals along the survey line. We obtained estimates gas content profiles at 14 locations along a 1.4 km transect using multi-frequency CMPs. Geophysical data was supplemented with direct gas sampling at selected locations. One-dimensional vertical electromagnetic wave velocity models were developed using the Dix relation to calculate velocities for discrete intervals. The Complex Refractive Index Model (CRIM) was applied to convert these velocities into gas content estimates. Clear variations in subsurface gas accumulation are apparent between landforms with fen sites showing homogeneous gas profiles and bog crest locations exhibiting evidence for extensive trapping of free phase gas at depth.

  17. The influence of climate on peatland extent in Western Siberia since the Last Glacial Maximum.

    PubMed

    Alexandrov, G A; Brovkin, V A; Kleinen, T

    2016-01-01

    Boreal and subarctic peatlands are an important dynamical component of the earth system. They are sensitive to climate change, and could either continue to serve as a carbon sink or become a carbon source. Climatic thresholds for switching peatlands from sink to source are not well defined, and therefore, incorporating peatlands into Earth system models is a challenging task. Here we introduce a climatic index, warm precipitation excess, to delineate the potential geographic distribution of boreal peatlands for a given climate and landscape morphology. This allows us to explain the present-day distribution of peatlands in Western Siberia, their absence during the Last Glacial Maximum, their expansion during the mid-Holocene, and to form a working hypothesis about the trend to peatland degradation in the southern taiga belt of Western Siberia under an RCP 8.5 scenario for the projected climate in year 2100. PMID:27095029

  18. The influence of climate on peatland extent in Western Siberia since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Alexandrov, G. A.; Brovkin, V. A.; Kleinen, T.

    2016-04-01

    Boreal and subarctic peatlands are an important dynamical component of the earth system. They are sensitive to climate change, and could either continue to serve as a carbon sink or become a carbon source. Climatic thresholds for switching peatlands from sink to source are not well defined, and therefore, incorporating peatlands into Earth system models is a challenging task. Here we introduce a climatic index, warm precipitation excess, to delineate the potential geographic distribution of boreal peatlands for a given climate and landscape morphology. This allows us to explain the present-day distribution of peatlands in Western Siberia, their absence during the Last Glacial Maximum, their expansion during the mid-Holocene, and to form a working hypothesis about the trend to peatland degradation in the southern taiga belt of Western Siberia under an RCP 8.5 scenario for the projected climate in year 2100.

  19. The influence of climate on peatland extent in Western Siberia since the Last Glacial Maximum

    PubMed Central

    Alexandrov, G. A.; Brovkin, V. A.; Kleinen, T.

    2016-01-01

    Boreal and subarctic peatlands are an important dynamical component of the earth system. They are sensitive to climate change, and could either continue to serve as a carbon sink or become a carbon source. Climatic thresholds for switching peatlands from sink to source are not well defined, and therefore, incorporating peatlands into Earth system models is a challenging task. Here we introduce a climatic index, warm precipitation excess, to delineate the potential geographic distribution of boreal peatlands for a given climate and landscape morphology. This allows us to explain the present-day distribution of peatlands in Western Siberia, their absence during the Last Glacial Maximum, their expansion during the mid-Holocene, and to form a working hypothesis about the trend to peatland degradation in the southern taiga belt of Western Siberia under an RCP 8.5 scenario for the projected climate in year 2100. PMID:27095029

  20. The Influence of Landscape Morphology on Peatland Dynamics and Carbon Accumulation Inferred from Ground Penetrating Radar (GPR) and Peat Core Analysis

    NASA Astrophysics Data System (ADS)

    Loisel, J.; Nolan, J. T.; Yu, Z.; Parkesian, A.; Slater, L. D.

    2010-12-01

    Northern peatlands have potential for strong feedbacks on the climate system through their impact on the global carbon (C) cycle. Since the Last Glacial Maximum, these ecosystems have sequestered about 550 Gt of organic C (Yu et al. 2010, GRL) and have been important sources of methane to the atmosphere. Over this period, peatlands have spread throughout the northern landscape to cover approximately 3% of today’s global land surface. As peatland dynamics are complex and often non-linear, however, patterns of regional peatland area expansion remain speculative, despite the critical role this spatio-temporal aspect plays in Holocene C stock and flux estimates. Using near-surface geophysics and peat core analysis, we show that slope gradient and basin topography exert deterministic controls on peatland lateral expansion and C accumulation. Our study was conducted in a 14,000 year-old sloping peatland complex (62°N, 150°W) whose growth was interrupted for about 1000 years when Mt. Hayes erupted between 4390 and 3430 cal. BP. Peat thickness and subsurface topography were obtained using GPR combined with high-resolution surface elevation data. The continuous, 15 cm-thick tephra layer was clearly visible in the GPR surveys and was used as a chronostratigraphic marker to delineate ‘post-tephra’ peatland dynamics. Radiocarbon dating was performed on post-tephra peat sediments. Results indicate rapid peat re-colonization (taking < 300 years) throughout the basin following the ashfall event. The observed lateral expansion rate suggests there is a slope threshold (≈ 1°) below which peat seems to spread rapidly. Lateral expansion rates were significantly slower (> 10,000 years) under the initial geomorphic conditions (with a slope ≈ 2°). Under the reasonable assumption that post-tephra peatland dynamics were primarily affected by tephra-modified topography, and not by time or climate, we calculated peat C accumulation rates (PCAR) for the past 3000 years using

  1. Extent and status of mires, peatlands, and organic soils in Europe

    NASA Astrophysics Data System (ADS)

    Tanneberger, Franziska; Barthelmes, Alexandra; Tegetmeyer, Cosima; Busse, Stephan; Joosten, Hans

    2016-04-01

    Key words: peatland distribution, peatland drainage, GIS, Global Peatland Database, European Mires Book The relevance of drained peatlands to climate change due to emission of huge amounts of greenhouse gases has recently been recognised e.g. by IPCC, FAO, and the European Union. Oppositely, natural and restored peatlands provide ecosystem services like enhancing biodiversity, nutrient retention, groundwater storage, flood mitigation, and cooling. To evaluate the drainage status of peatlands and organic soils and to develop specific restoration strategies comprehensive and exact geospatial data are needed. The Global Peatland Database (GPD) is hosted at Greifswald Mire Centre (http://tiny.cc/globalpeat). Currently, it provides estimates on location, extent, and drainage status of peatlands and organic soils for 268 countries and regions of the world. Due to the large diversity of definitions and terms for peatlands and organic soils, this mapping follows the broad definition of organic soils from IPCC that gives a minimum soil organic carbon threshold of 12% and considers any depth of the organic layer larger than 10 cm. GIS datasets are continuously collected, specific terms and definitions analysed and the completeness and accuracy of the datasets evaluated. Currently, the GPD contains geospatial data on peatlands and organic soils for all European countries (except Moldova). Recent information on status, distribution, and conservation of mires and peatlands in Europe is summarised in the European Mires Book. It includes descriptions from 49 countries and other geographic entities in Europe. All country chapters follow a generic structure and include also extensive descriptions of national terminology (also in national languages and script) and typologies as well as up to date area statistics and maps. They are complemented by integrative chapters presenting mire classification, mire regionality, peatland use, and mire conservation in Europe. The European Mires

  2. Evaluation of the Holocene Peat Model with Data from Boreal and Subarctic Peatlands of the James Bay Lowlands, Quebec, Canada

    NASA Astrophysics Data System (ADS)

    Quillet, A.; Garneau, M.; Frolking, S.; Roulet, N. T.; van Bellen, S.; Ali, A. A.; Booth, R. K.; Peng, C.

    2008-12-01

    The Holocene Peat Model (HPM) is a dynamic model simulating the transient evolution of a peatland since its early stages. HPM takes into account the feedbacks between vegetation, peat properties, water table depth, and climate. The aim of this study is to evaluate the HPM by means of empirical data. Three distinct sampling sites were chosen within a large region including boreal and subarctic peatlands in the James Bay lowlands, northern Quebec, Canada. One fen and one bog were selected in the subarctic region and another bog in the boreal region. These sites have different geographical, climatological and ecological features (e.g. pH, nutrient availability, hydrology and species composition). Five cores from those three sites were dated using 210Pb and 14C. Loss on ignition and plant macrofossils analysis were performed for each core. First, we compare the simulation results of the HPM for the study sites with the information earned in the field and laboratory. In order to capture the causes for discrepancies between simulated and observed data, we then constrained the model in two ways: 1) The water balance of HPM was forced with water table fluctuations reconstructions, obtained from a transfer function of Testate amoebae. 2) The bulk density of HPM was forced with the bulk density data obtained from the cores. In both cases, the results highlight the effectiveness of the water balance and the bulk density routines of the HPM and also draw attention to other potential causes of inaccuracy in the model.

  3. The effect of long-term water table manipulations on dissolved organic carbon dynamics in a poor fen peatland

    NASA Astrophysics Data System (ADS)

    Hribljan, John A.; Kane, Evan S.; Pypker, Thomas G.; Chimner, Rodney A.

    2014-04-01

    Dissolved organic carbon (DOC) production, consumption, and quality displayed differences after long-term (~55 years) hydrological alterations in a poor fen peatland in northern Michigan. The construction of an earthen levee resulted in areas of a raised and lowered water table (WT) relative to an unaltered intermediate WT site. The lowered WT site had greater peat aeration and larger seasonal vertical WT fluctuations that likely elevated peat decomposition and subsidence with subsequent increases in bulk density, vertical hydraulic gradient, decreased hydraulic conductivity (Ksat), and a greater pore water residence time relative to the unaltered site. The raised WT site displayed a decreased Ksat combined with seasonal upwelling events that contributed to a longer residence time in comparison to the unaltered site. These differences are potentially contributing to elevated DOC concentrations at the lowered and raised WT site relative to the unaltered site. Additionally, spectrophotometric indices and chemical constituent assays indicated that the lowered site DOC was more aromatic and contained elevated concentrations of phenolics compared to the intermediate site. The raised site DOC was less aromatic, less humified, and also had a greater phenolic content than the intermediate site. Furthermore, an incubation experiment showed that DOC in the raised site contained the greatest labile carbon source. Based on our results, long-term WT alterations will likely impose significant effects on DOC dynamics in these peatlands; however, WT position alone was not a good predictor of DOC concentrations, though impoundment appears to produce a more labile DOC whereas drainage increases DOC aromaticity.

  4. Climate and peat type in relation to spatial variation of the peatland carbon mass in the Hudson Bay Lowlands, Canada

    NASA Astrophysics Data System (ADS)

    Packalen, Maara S.; Finkelstein, Sarah A.; McLaughlin, James W.

    2016-04-01

    Northern peatlands store ~500 Pg of carbon (C); however, controls on the spatial distribution of the stored C may differ regionally, owing to the complex interaction among climate, ecosystem processes, and geophysical controls. As a globally significant C sink, elucidation of controls on the distribution of C in the Hudson Bay Lowlands, Canada (HBL), is of particular importance. Although peat age is related to timing of land emergence and peat depth in the HBL, considerable variation in the total C mass (kg m-2) among sites of similar peat age suggests that other factors may explain spatial patterns in C storage (Pg) and sequestration. Here we quantify the role of two key factors in explaining the spatial distribution of the C mass in the HBL (n = 364 sites), (i) climate variability and (ii) peat lithology, for two major peatland classes in the HBL (bogs and fens). We find that temperature, precipitation, and evapotranspiration each explained nearly half of the C mass variability. Regions characterized by warmer and wetter conditions stored the most C as peat. Our results show that bogs and fens store similar amounts of C within a given climate domain, although via distinct storage mechanisms. Namely, fen peats tend to be shallower and more C dense (kg m-3) compared to bogs. Following geophysical controls on the timing of peat initiation, our results reveal that both the widespread bog-fen patterning and variability in regional climate contribute to explaining the spatial distribution of the peat C mass in the HBL.

  5. Isotopic partitioning of net ecosystem CO2 exchange reveals the importance of methane oxidation in a boreal peatland

    NASA Astrophysics Data System (ADS)

    Hasselquist, Niles; Peichl, Matthias; Öquist, Mats; Crill, Patrick; Nilsson, Mats

    2016-04-01

    Partitioning net ecosystem CO2 exchange (NEE) into its different flux components is crucial as it provides a mechanistic framework to better assess how the terrestrial carbon cycle may respond to projected environmental change. This is especially important for northern boreal peatlands, which store approximately one-quarter of the world's soil carbon and yet at the same time are projected to experience some of the greatest environmental changes in the future. Using an experimental setup with automated chambers for measuring NEE (transparent chambers), ecosystem respiration (Reco; opaque chambers) and heterotrophic respiration (Rh; opaque chambers on vegetation-free trenched plots) in combination with continuous measurements of δ13C using near-infrared, diode-laser-based cavity-ring down spectroscopy (Picarro G1101-i analyzer), we partitioned NEE of CO2 into gross primary productivity (GPP), ecosystem respiration (Reco), heterotrophic respiration (Rh) and autotrophic respiration (Ra) using two different approaches (i.e., chamber- and isotope-based methods) in a boreal peatland in northern Sweden (Degerö). Given that δ13C was continuously measured in each chamber, we were also able to further partition Rh into soil organic matter (SOM) mineralization by saprotrophic microbes and the oxidation of methane (CH4) by methanotrophic bacteria. During the ten day measurement period (in late July 2014), the average daily NEE flux at the mire was -0.6 g C m-2 d-1. Overall, the two partitioning approaches yielded similar estimates for the different NEE component fluxes. Average daily fluxes of Rh and Ra were similar in magnitude, yet these two flux components showed contrasting diurnal responses: Ra was greatest during the day whereas there was little diurnal variation in Rh. In general, average 13C signature of CO2 efflux from the Rh chambers (-41.1 ± 0.6 ‰) was between the 13C signature of SOM (-25.8 ± 0.6 ‰) and CH4 in pore water (-69.0 ± 0.8 ‰). Assuming that

  6. Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland

    NASA Astrophysics Data System (ADS)

    Hodgkins, Suzanne B.; Tfaily, Malak M.; Podgorski, David C.; McCalley, Carmody K.; Saleska, Scott R.; Crill, Patrick M.; Rich, Virginia I.; Chanton, Jeffrey P.; Cooper, William T.

    2016-08-01

    The fate of carbon stored in permafrost-zone peatlands represents a significant uncertainty in global climate modeling. Given that the breakdown of dissolved organic matter (DOM) is often a major pathway for decomposition in peatlands, knowledge of DOM reactivity under different permafrost regimes is critical for determining future climate feedbacks. To explore the effects of permafrost thaw and resultant plant succession on DOM reactivity, we used a combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), UV/Vis absorbance, and excitation-emission matrix spectroscopy (EEMS) to examine the DOM elemental composition and optical properties of 27 pore water samples gathered from various sites along a permafrost thaw sequence in Stordalen Mire, a thawing subarctic peatland in northern Sweden. The presence of dense Sphagnum moss, a feature that is dominant in the intermediate thaw stages, appeared to be the main driver of variation in DOM elemental composition and optical properties at Stordalen. Specifically, DOM from sites with Sphagnum had greater aromaticity, higher average molecular weights, and greater O/C, consistent with a higher abundance of phenolic compounds that likely inhibit decomposition. These compounds are released by Sphagnum and may accumulate due to inhibition of phenol oxidase activity by the acidic pH at these sites. In contrast, sites without Sphagnum, specifically fully-thawed rich fens, had more saturated, more reduced compounds, which were high in N and S. Optical properties at rich fens indicated the presence of microbially-derived DOM, consistent with the higher decomposition rates previously measured at these sites. These results indicate that Sphagnum acts as an inhibitor of rapid decomposition and CH4 release in thawing subarctic peatlands, consistent with lower rates of CO2 and CH4 production previously observed at these sites. However, this inhibitory effect may disappear if Sphagnum-dominated bogs

  7. Hydrology and hydraulics of treatment wetlands constructed on drained peatlands

    NASA Astrophysics Data System (ADS)

    Postila, Heini; Ronkanen, Anna-Kaisa; Kløve, Bjørn

    2013-04-01

    Treatment wetlands are globally used for wastewater purification purposes. In Finland, these wetlands are commonly peatland-based and are used to treat runoff from peat extraction sites and peatland forestry. Wetlands are also used for polishing municipal wastewaters and mining waters. In peat extraction the structures are usually called overland flow areas (OFAs), which are traditionally established on pristine peatlands. However, nowadays establishing of new peat extraction sites is guided to drained peatland areas due to the Finnish Peat Use Strategy, which leads difficulties to find undisturbed peatland area for OFA. Therefore treatment wetlands have had to construct also on drained peatland areas. In drained areas peat physical properties have changed due to oxidation and subsidence and the water flow pathways differs from OFAs flow patterns, which maybe have effect on purification results. Thus in the present study we aim to clarify the hydrology and hydraulic properties of treatment wetlands constructed on drained peatland areas. For this purposes, 20 treatment wetlands on drained peatland areas across Finland were detailed measured for peat hydraulic conductivity. In selected areas, runoff was continuously monitored, flow distribution at treatment areas was studied and water residence times measured with tracer tests using potassium iodide (KI). Generally, in the study areas, the ditches had been completely blocked, partly blocked e.g with peat dams or not blocked at all. The ditches were located partly parallel to the flow direction and partly perpendicular to it. The distribution of water to the wetlands has been implemented in many different ways e.g. by distribution ditch or by perforated pipes. Based on the results, in majority of the wetlands, the peat drainage has clearly affected the hydraulic properties of wetlands, but not on all sites. In more than half of the wetlands (12), the median hydraulic conductivity of peat drastically decreased at the

  8. How sensitive is the global peatland carbon pool to climate change?

    NASA Astrophysics Data System (ADS)

    Talbot, J.; Frolking, S. E.

    2010-12-01

    Peatlands are important components of boreal and subarctic landscapes, and can be regionally important components of tropical landscapes. As boreal and subarctic peatlands store about one-third of the terrestrial soil carbon pool, peatlands play an important role as a long-term sink for carbon . In the last two decades, many studies have looked at the vulnerability of this carbon pool to the effects of global change (particularly warming and drying), and the potential feedbacks to the atmosphere a change in the peatland carbon pool might bring. The persistent imbalance between the production of decomposition of organic matter in waterlogged conditions results in the accumulation of peat. We synthesized studies looking at the effect of global change (especially warming and drying) on the carbon balance of peatlands. This synthesis shows that the magnitude of the warming or drying required to significantly affect the global peatland carbon pool is higher than the change that is expected over the 21st century, although this conclusion might be different when taking into account the effects of an increase in natural fire frequency or widespread permafrost thaw. We also show that direct anthropogenic impacts on peatlands, especially tropical peatlands, could result in the release of more peatland carbon in the 21st century than warming and/or drying. The simulation of peat accumulation responses to different drying scenarios using the Holocene Peatland Model also indicates that a very sharp and sustained decline in water table depth is required to significantly affect the carbon pool of a mature peatland, and that this response differs depending on how the vegetation is allowed to change in the course of the simulations.

  9. Land-use Changes on Peatlands in Russia and Green House Gas Emissions

    NASA Astrophysics Data System (ADS)

    Sirin, A.; Minaeva, T.; Chistotin, M.; Glagolev, M.; Suvorov, G.

    2009-04-01

    Russia possesses vast areas of peatlands and associated paludified shallow peat lands, over 8 and 20% respectively. The country is the largest World peatland nation, and thus could be responsible for the large part of GHG exchange between peatlands and the atmosphere. Russian peatlands present a high variety of natural conditions from permafrost mires to bogs, fens and swamps within boreal, temperate, steppe and semi-arid zones, which have quite different rates of GHG flux, emitting or absorbing carbon dioxide and methane. Many regions of Russia still contain vast areas of virgin mires but in the central European part of Russia, West Siberia and Far East the appreciable part of peatlands was already modified. Peatlands were used in a broad spectrum of human activities connected with direct water level draw-down: peat extraction for different purposes (up to 1.5 million ha), drainage for agriculture, and drainage for forestry (each over 3 million ha). Many peatlands all the over the country were affected by infrastructure development (by road, pipe line construction etc.) with related changes of their hydrology and GHG fluxes. These land uses are under consideration of LULUFC issues of UNFCCC, and peat excavation is directly included in IPCC 2006 Guidelines as a main wetland/peatland land use activity related to climate change mitigation. General estimates and geographical distribution of peatlands drained for agriculture and forestry as well as peatlands under excavation, extracted or abandoned are given based on existing statistical and sectoral information. GHG fluxes from disturbed peatlands are analyzed using available Russian data and the results of specially organized observations in 2004-2008 in the pilot regions in Central European Russia and West Siberia which included a variety of modified and virgin control sites.

  10. Climate Change Driven Implications on Spatial Distribution of High Andean Peatlands in the Central Andes

    NASA Astrophysics Data System (ADS)

    Otto, Marco; Gibbons, Richard E.

    2013-04-01

    High Andean peatlands are among the most unique habitats in the tropical Andes and certainly among the least studied. High Andean peatlands occur patchily in montane grassland and scrub below snow line and above tree line. These high-elevation peatlands are sustained by glacial runoff and seasonal precipitation. We used remote sensing data to estimate that peatland habitat is approximately 2.5 % of our study region in the Puna, an ecoregion located in the high Andes above 4000 m a.s.l. Individual sizes of our estimated peatland polygons ranged from 0.72 ha to 1079 ha with a mean size of 4.9 ha. Climate change driven implications on spatial distribution of high Andean peatlands were assessed in two ways. First, we estimated the effect of predicted regional temperature increase by using the standard lapse rate of 2° C per 300 m for assessing peatland habitat patches that would remain above a critical thermocline. Nearly 80% of peatland habitat patches were predicted to occur below the thermocline if the prediction of 4° C temperature increase is realized. The second assessment relied on the quantified assumption that permanent snow or glacier cover, topographic characteristics (e.g. slope) and precipitation of a basin are essential variables in the occurrence of high Andean peatlands. All 17 basins were predicted to have a decrease in peatland habitat due to snow line uplift, decrease in precipitation and consequent insufficient wetland inflows. Total habitat loss was predicted for two basins in the semi-arid part of the study area with a snow line uplift to 5600 m and a projected decrease in precipitation of 1 mm per year over the next 40 years. A combined result of both assessments provides important information on climate change driven implications on the hydrology of high Andean peatlands and potential consequences for their spatial distribution within the Central Andes.

  11. WikiPEATia - a web based platform for assembling peatland data through ‘crowd sourcing’

    NASA Astrophysics Data System (ADS)

    Wisser, D.; Glidden, S.; Fieseher, C.; Treat, C. C.; Routhier, M.; Frolking, S. E.

    2009-12-01

    The Earth System Science community is realizing that peatlands are an important and unique terrestrial ecosystem that has not yet been well-integrated into large-scale earth system analyses. A major hurdle is the lack of accessible, geospatial data of peatland distribution, coupled with data on peatland properties (e.g., vegetation composition, peat depth, basal dates, soil chemistry, peatland class) at the global scale. This data, however, is available at the local scale. Although a comprehensive global database on peatlands probably lags similar data on more economically important ecosystems such as forests, grasslands, croplands, a large amount of field data have been collected over the past several decades. A few efforts have been made to map peatlands at large scales but existing data have not been assembled into a single geospatial database that is publicly accessible or do not depict data with a level of detail that is needed in the Earth System Science Community. A global peatland database would contribute to advances in a number of research fields such as hydrology, vegetation and ecosystem modeling, permafrost modeling, and earth system modeling. We present a Web 2.0 approach that uses state-of-the-art webserver and innovative online mapping technologies and is designed to create such a global database through ‘crowd-sourcing’. Primary functions of the online system include form-driven textual user input of peatland research metadata, spatial data input of peatland areas via a mapping interface, database editing and querying editing capabilities, as well as advanced visualization and data analysis tools. WikiPEATia provides an integrated information technology platform for assembling, integrating, and posting peatland-related geospatial datasets facilitates and encourages research community involvement. A successful effort will make existing peatland data much more useful to the research community, and will help to identify significant data gaps.

  12. Vegetation management with fire modifies peatland soil thermal regime.

    PubMed

    Brown, Lee E; Palmer, Sheila M; Johnston, Kerrylyn; Holden, Joseph

    2015-05-01

    Vegetation removal with fire can alter the thermal regime of the land surface, leading to significant changes in biogeochemistry (e.g. carbon cycling) and soil hydrology. In the UK, large expanses of carbon-rich upland environments are managed to encourage increased abundance of red grouse (Lagopus lagopus scotica) by rotational burning of shrub vegetation. To date, though, there has not been any consideration of whether prescribed vegetation burning on peatlands modifies the thermal regime of the soil mass in the years after fire. In this study thermal regime was monitored across 12 burned peatland soil plots over an 18-month period, with the aim of (i) quantifying thermal dynamics between burned plots of different ages (from <2 to 15 + years post burning), and (ii) developing statistical models to determine the magnitude of thermal change caused by vegetation management. Compared to plots burned 15 + years previously, plots recently burned (<2-4 years) showed higher mean, maximum and range of soil temperatures, and lower minima. Statistical models (generalised least square regression) were developed to predict daily mean and maximum soil temperature in plots burned 15 + years prior to the study. These models were then applied to predict temperatures of plots burned 2, 4 and 7 years previously, with significant deviations from predicted temperatures illustrating the magnitude of burn management effects. Temperatures measured in soil plots burned <2 years previously showed significant statistical disturbances from model predictions, reaching +6.2 °C for daily mean temperatures and +19.6 °C for daily maxima. Soil temperatures in plots burnt 7 years previously were most similar to plots burned 15 + years ago indicating the potential for soil temperatures to recover as vegetation regrows. Our findings that prescribed peatland vegetation burning alters soil thermal regime should provide an impetus for further research to understand the consequences of thermal regime

  13. Spatial variability in plant species composition and peatland carbon exchange

    NASA Astrophysics Data System (ADS)

    Goud, E.; Moore, T. R.; Roulet, N. T.

    2015-12-01

    Plant species shifts in response to global change will have significant impacts on ecosystem carbon (C) exchange and storage arising from changes in hydrology. Spatial variation in peatland C fluxes have largely been attributed to the spatial distribution of microhabitats that arise from variation in surface topography and water table depth, but little is known about how plant species composition impacts peatland C cycling or how these impacts will be influenced by changing environmental conditions. We quantified the effect of species composition and environmental variables on carbon dioxide (CO2) and methane (CH4) fluxes over 2 years in a temperate peatland for four plant communities situated along a water table gradient from ombrotrophic bog to beaver pond. We hypothesized that (i) spatial heterogeneity in species composition would drive predictable spatial heterogeneity in C fluxes due to variation in plant traits and ecological tolerances, and (ii) increases in peat temperature would increase C fluxes. Species had different effects on C fluxes primarily due to differences in leaf traits. Differences in ecological tolerances among communities resulted in different rates of CO2 exchange in response to changes in water table depth. There was an overall reduction in ecosystem respiration (ER), gross primary productivity (GPP) and CH4 flux in response to colder peat temperatures in the second year, and the additive effects of a deeper water table in the bog margin and pond sites further reduced flux rates in these areas. These results demonstrate that different plant species can increase or decrease the flux of C into and out of peatlands based on differences in leaf traits and ecological tolerances, and that CO2 and CH4 fluxes are sensitive to changes in soil temperature, especially when coupled with changes in moisture availability.

  14. FY10 RARE Final Report to Region 10: The functional Assessment of Alaska Peatlands in Cook Inlet Basin - report

    EPA Science Inventory

    Peatlands in south central Alaska form the predominant wetland class in the lowlands that encompass Cook Inlet. These peatlands are also in areas of increasing human development in Alaska. Currently Alaska peatlands are extensive and largely pristine. This study focused onobtaini...

  15. Variations in dissolved organic carbon concentrations across peatland hillslopes

    NASA Astrophysics Data System (ADS)

    Boothroyd, I. M.; Worrall, F.; Allott, T. E. H.

    2015-11-01

    Peatlands are important terrestrial carbon stores and dissolved organic carbon (DOC) is one of the most important contributors to carbon budgets in peatland systems. Many studies have investigated factors affecting DOC concentration in peatland systems, yet hillslope position has been thus far overlooked as a variable that could influence DOC cycling. This study investigates the importance of hillslope position with regard to DOC cycling. Two upland peat hillslopes were studied in the Peak District, UK, to determine what impact, if any, hillslope position had upon DOC concentration. Hillslope position was found to be a significant factor affecting variation in soil pore water DOC concentration, with bottom-slope positions having significantly lower DOC concentrations than up-slope because of dilution of DOC as water moves down-slope and is flushed out of the system via lateral throughflow. Water table drawdown on steeper mid-slopes increased DOC concentrations through increased DOC production and extended residence times allowing a build-up of humic-rich DOC compounds. Hillslope position did not significantly affect DOC concentrations in surface runoff water because of the dilution of near-surface soil pore water by precipitation inputs, while stream water had similar water chemistry properties to soil pore water under low-flow conditions.

  16. Experimental sulfate amendment alters peatland bacterial community structure.

    PubMed

    Strickman, R J S; Fulthorpe, R R; Coleman Wasik, J K; Engstrom, D R; Mitchell, C P J

    2016-10-01

    As part of a long-term, peatland-scale sulfate addition experiment, the impact of varying sulfate deposition on bacterial community responses was assessed using 16S tag encoded pyrosequencing. In three separate areas of the peatland, sulfate manipulations included an eight year quadrupling of atmospheric sulfate deposition (experimental), a 3-year recovery to background deposition following 5years of elevated deposition (recovery), and a control area. Peat concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, were measured, the production of which is attributable to a growing list of microorganisms, including many sulfate-reducing Deltaproteobacteria. The total bacterial and Deltaproteobacterial community structures in the experimental treatment differed significantly from those in the control and recovery treatments that were either indistinguishable or very similar to one another. Notably, the relatively rapid return (within three years) of bacterial community structure in the recovery treatment to a state similar to the control, demonstrates significant resilience of the peatland bacterial community to changes in atmospheric sulfate deposition. Changes in MeHg accumulation between sulfate treatments correlated with changes in the Deltaproteobacterial community, suggesting that sulfate may affect MeHg production through changes in the community structure of this group. PMID:27267720

  17. Dual controls on carbon loss during drought in peatlands

    NASA Astrophysics Data System (ADS)

    Wang, Hongjun; Richardson, Curtis J.; Ho, Mengchi

    2015-06-01

    Peatlands store one-third of global soil carbon. Drought/drainage coupled with climate warming present the main threat to these stores. Hence, understanding drought effects and inherent feedbacks related to peat decomposition has been a primary global challenge. However, widely divergent results concerning drought in recent studies challenge the accepted paradigm that waterlogging and associated anoxia are the overarching controls locking up carbon stored in peat. Here, by linking field and microcosm experiments, we show how previously unrecognized mechanisms regulate the build-up of phenolics, which protects stored carbon directly by reducing phenol oxidase activity during short-term drought and, indirectly, through a shift from low-phenolic Sphagnum/herbs to high-phenolic shrubs after long-term moderate drought. We demonstrate that shrub expansion induced by drought/warming in boreal peatlands might be a long-term self-adaptive mechanism not only increasing carbon sequestration but also potentially protecting historic soil carbon. We therefore propose that the projected `positive feedback loop’ between carbon emission and drought in peatlands may not occur in the long term.

  18. 10Be ages of glacial and meltwater features northwest of Lake Superior: a chronology of Laurentide Ice sheet deglaciation and eastward flooding from Glacial Lake Agassiz

    NASA Astrophysics Data System (ADS)

    Kelly, M. A.; Fisher, T. G.; Lowell, T.; Barnett, P.; Schaefer, J. M.; Schwartz, R.

    2009-12-01

    Significant controversy exists as to the role of Laurentide Ice Sheet meltwater in causing the Younger Dryas cold event. Recently, Lowell et al. (2009) presented a radiocarbon chronology of Laurentide Ice Sheet deglaciation along a north-south transect located northwest of Lake Superior. These authors concluded that the presence of the Laurentide Ice Sheet precluded an eastward drainage of glacial Lake Agassiz until mid-Younger Dryas time. Here, we use 10Be surface exposure dating to examine the timing of the eastward drainage of Lake Agassiz. We present 10Be ages of moraines and erratic boulders in meltwater pathways along the same transect as Lowell et al. (2009), northwest of Lake Superior. In general, 10Be ages of glacial features are similar to, or slightly older than, basal radiocarbon ages of nearby lakes. Based on the 10Be chronology, deglaciation of the Laurentide Ice Sheet in this region occurred between ~13,000 and 10,000 yr BP. We also present the first direct ages of flood deposits in bedrock channels presumably associated with the eastern drainage of Lake Agassiz. Evidence for flooding includes extensive channels incised into bedrock and enormous bedforms located north of Lake Superior. 10Be ages of two flood deposits near the Roaring River and Mundell Lake yield mean 10Be ages of ~11,700 and 11,000 yr BP, respectively. These ages indicate that occupation of the channels postdates initiation of the Younger Dryas by more than 1,000 years and are in general agreement with a basal radiocarbon age from nearby Lower Vail Lake (Teller et al., 2005). Preliminary paleohydrological estimates based on bedform clast sizes and channel geometries are velocities and discharges of 2.8-19.8 ms-1 and 4,200-30,000 m3s-1 at the Roaring River location and 2.5-17.5 ms-1 and 49,000-349,000 m3s-1 at the Mundell Lake location.

  19. Warming-induced reduced peat accrual rates and potential C losses in Northern U.S

    NASA Astrophysics Data System (ADS)

    Fissore, C.; Nater, E. A.; Moskun, A.; Klein, A.; Le, T.

    2013-12-01

    Peatlands located at northern latitudes represent a sink of carbon (C) that is at risk of being lost to the atmosphere if current and expected changes in climate accelerate existing C stock decomposition rates. The extent of such potential loss is still unknown, but recent studies suggest that accrual rate of this critical C stock may be in decline due to more rapid decomposition of plant material reaching the soil. The consequences for our climate system can be significant. If large amounts of C currently ';locked' belowground in peatland ecosystems were to be decomposed and hence lost to the atmosphere, atmospheric concentration of CO2 would increase, causing further warming and hence even more rapid decomposition of peatland C. Our objective in this study is to investigate and compare past and more recent rates of C accrual in peatlands to determine if the rates of C accrual are declining. We collected intact frozen blocks of peat from three sites in Northern Minnesota and sectioned them into horizontal slices, which are being dated by 137Cs and 14C. Atmospheric concentrations of both 137Cs and 14C spiked in the 1960's due to nuclear bomb testing, leaving a ';signature' in organic matter (14C) and sediments (137Cs). The signal has steadily declined since that time. Detection of the signal in current soil samples will allow us to date the sample and consequently to measure the quantity of C accrued in the peat over various measured time intervals.

  20. Improving Indonesian peatland C stock estimates using ground penetrating radar (GPR) and electrical resistivity imaging (ERI)

    NASA Astrophysics Data System (ADS)

    Terry, N.; Comas, X.; Slater, L. D.; Warren, M.; Kolka, R. K.; Kristijono, A.; Sudiana, N.; Nurjaman, D.; Darusman, T.

    2014-12-01

    Tropical peatlands sequester an estimated 15% of the carbon pool from peatlands worldwide. Indonesian peatlands account for approximately 65% of all tropical peat, and are believed to be the largest global source of carbon dioxide emissions to the atmosphere from degrading peat. However, there is great uncertainty in these estimates due to insufficient data regarding the thickness of organic peat soils and their carbon content. Meanwhile, Indonesian peatlands are threatened by heightening pressure to drain and develop. Indirect geophysical methods have garnered interest for their potential to non-invasively estimate peat depth and gas content in boreal peatlands. Drawing from these techniques, we employed ground penetrating radar (GPR) and electrical resistivity imaging (ERI) in tandem with direct methods (core sampling) to evaluate the potential of these methods for tropical peatland mapping at 2 distinct study sites on West Kalimantan (Indonesia). We find that: [1] West Kalimantan peatland thicknesses estimated from GPR and ERI in intermediate/shallow peat can vary substantially over short distances (for example, > 2% over less than 0.02° surface topography gradient), [2] despite having less vertical resolution, ERI is able to better resolve peatland thickness in deep peat, and [3] GPR provides useful data regarding peat matrix attributes (such as the presence of wood layers). These results indicate GPR and ERI could help reduce uncertainty in carbon stocks and aid in responsible land management decisions in Indonesia.

  1. Do peatlands or lakes provide the most comprehensive distal tephra records?

    NASA Astrophysics Data System (ADS)

    Watson, E. J.; Swindles, G. T.; Lawson, I. T.; Savov, I. P.

    2016-05-01

    Despite the widespread application of tephra studies for dating and correlation of stratigraphic sequences ('tephrochronology'), questions remain over the reliability and replicability of tephra records from lake sediments and peats, particularly in sites >1000 km from source volcanoes. To address this, we examine the tephrostratigraphy of four pairs of lake and peatland sites in close proximity to one another (<10 km), and evaluate the extent to which the microscopic (crypto-) tephra records in lakes and peatlands differ. The peatlands typically record more cryptotephra layers than nearby lakes, but cryptotephra records from high-latitude peatlands can be incomplete, possibly due to tephra fallout onto snow and subsequent redistribution across the peatland surface by wind and during snowmelt. We find no evidence for chemical alteration of glass shards in peatland or lake environments over the time scale of this study (mid-to late- Holocene). Instead, the low number of basaltic cryptotephra layers identified in distal peatlands reflects the capture of only primary tephra-fall, whereas lakes concentrate tephra falling across their catchments which subsequently washes into the lake, adding to the primary tephra fallout received in the lake. A combination of records from both lakes and peatlands must be used to establish the most comprehensive and complete regional tephrostratigraphies. We also describe two previously unreported late Holocene cryptotephras and demonstrate, for the first time, that Holocene Icelandic ash clouds frequently reached Arctic Sweden.

  2. MANAGEMENT OF PEATLAND SHRUB- AND FOREST-DOMINATED COMMUNITIES FOR THREATENED AND ENDANGERED SPECIES

    EPA Science Inventory

    Plant communities found on peatland soils include forests, basin shrublands, and seepage communities. The ecology and management of six communities are reviewed, with an emphasis on land uses associated with Department of Defense (DoD) installations. Peatland plant communities in...

  3. Effect of water level drawdown on decomposition in boreal peatlands

    NASA Astrophysics Data System (ADS)

    Straková, Petra; Penttilä, Timo; Laiho, Raija

    2010-05-01

    Plant litter production and decomposition are key processes in element cycling in most ecosystems. In peatlands, there has been a long-term imbalance between litter production and decay caused by high water levels (WL) and consequent anoxia. This has resulted in peatlands being a significant sink of carbon (C) from the atmosphere. However, peatlands are experiencing both "natural" (global climate change) and anthropogenic (ditching) changes that threaten their ability to retain this ecosystem identity and function. Many of these alterations can be traced back to WL drawdown, which can cause increased aeration, higher acidity, falling temperatures, and a greater probability of drought. Such changes are also associated with an increasing decomposition rate, and therefore a greater amount of C released back to the atmosphere. Yet studies about how the overall C balance of peatlands will be affected have come up with conflicting conclusions, demonstrating that the C store could increase, decrease, or remain static. A factor that has been largely overlooked is the change in litter type composition following persistent WL drawdown. It is the aim of our study, then, to help to resolve this issue. We studied the effects of short-term (ca. 4 years) and long-term (ca. 40 years) persistent WL drawdown on the decomposition of numerous types of above-ground and below-ground plant litters at three boreal peatland sites: bog, oligotrophic fen and mesotrophic fen. We thus believe that enough permutations have been created to obtain a good assessment of how each factor, site nutrient level, WL regime, and litter type composition, influences decomposition. We used the litter bag method to measure the decomposition rates: placed measured amounts of plant litter, or cellulose strips as a control, into closed mesh bags, and installed the bags in the natural environment for decomposition for each litter type for varying amounts of time. Following litter bag recovery, the litter was

  4. Postglacial sedimentary infill of the Bricial peatland (Cantabrian Mountains, Spain)

    NASA Astrophysics Data System (ADS)

    Correia, Antonio; Ruiz-Fernández, Jesús; Oliva, Marc; Fernández, Antonio; García-Hernández, Cristina; Gallinar, David

    2016-04-01

    Bricial is a peatland located in a glaciokarst depression of the Western Massif of the Picos de Europa (NW Spain). The depression is 425 m long and 245 m wide, and it is surrounded by moraines built during the stage of glacial expansion after the maximum advance within the Last Glaciation. In contrast to what happens in other karstic depressions existing in this massif (e.g. Comeya), the thickness and sedimentary infill of this depression is still unknown. With the purpose of better knowing the depression's structure, two electrical resistivity tomographies (ERT)s with different lengths across the Bricial depression were conducted along perpendicular directions; the shortest ERT was done in a NNE-SSW direction with an electrode spacing of 2 m and a total length of 78 m; the longest ERT was done in a WNW-ESE direction with a 5 m electrode spacing and a total length of 195 m. Both ERTs used 40 electrodes in a Wenner configuration. The two ERTs were done in such way that they intersected near an 8 m deep borehole drilled in the area in 2006. A two-dimensional electrical inversion software was used for inverting the apparent electrical resistivity data obtained during the field work into two-dimensional models of electrical resistivity of the ground. The models are a representation of the distribution of the electrical resistivity of the ground to depths of about 14 m along the shortest ERT and 35 m along the longest. In both geoelectrical models the electrical structure is approximately horizontal at the surface (i.e., between 3 to 5 m depth) and is more complex as depth increases. Low resistivity values prevail in most part of the profiles, which is consistent with the sedimentary sequence collected in the area. The 8 m long sedimentary sequence collected from Bricial consists of homogeneous organic-rich sediments. The base of the sequence was dated at 11,150 ± 900 cal yr BP. Taking into account the sedimentation rates and the data inferred from the electrical

  5. Ecological restoration of peatlands in steppe and forest-steppe areas

    NASA Astrophysics Data System (ADS)

    Minayeva, Tatiana; Sirin, Andrey; Dugarjav, Chultem

    2016-04-01

    Peatlands in the arid and semi-arid regions of steppe and forest steppe belt of Eurasia have some specific features. That demands the special approach to their management and restoration. The distribution of peatlands under conditions of dry climate is very limited and they are extremely vulnerable. Peatlands in those regions are found in the highlands where temperate conditions still present, in floodplains where they can get water from floods and springs, or in karst areas. Peatlands on watersheds present mainly remains from the more humid climate periods. Water and carbon storage as well as maintenance of the specific biodiversity are the key ecosystem natural functions of peatlands in the steppe and forest steppe. The performance of those functions has strong implications for people wellness and livelihood. Anyhow, peatlands are usually overlooked and poorly represented in the systems of natural protected areas. Land management plans, mitigation and restoration measures for ecosystems under use do not usually include special measures for peatlands. Peatlands'use depends on the traditional practices. Peat extraction is rather limited in subhumid regions but still act as one of the threats to peatlands. The most of peatlands are used as pastures and grasslands. In densely populated areas large part of peatlands are transformed to the arable lands. In many cases peatlands of piedmonts and highlands are affected by industrial developments: road construction, mining of subsoil resources (gold, etc.). Until now, the most of peatlands of steppe and forest steppe region are irreversibly lost, what also effects water regime, lands productivity, biodiversity status. To prevent further dramatic changes the ecological restoration approach should be introduced in the subhumid regions. The feasibility study to assess the potential for introducing ecological restoration techniques for peatlands in the arid and semi-arid conditions had been undertaken in steppe and forest

  6. Hydromorphological analysis and water balance modelling of ombro- and mesotrophic peatlands

    NASA Astrophysics Data System (ADS)

    Edom, F.; Münch, A.; Dittrich, I.; Keßler, K.; Peters, R.

    2010-10-01

    The hydromorphological analysis (HMA) is a method to quantify the potentials of mire revitalisation. In this study, the HMA is combined with the new peatland-tool of the water balance model AKWA-M®. This peatland-tool includes as well depth functions of the hydraulic conductivity and drainable porosity for several mire-ecotope-types as specific equations for mire evapotranspiration. The calculations were applied in several peatlands and mires of the German-Czech Ore Mountains (Erzgebirge/Krušné hory). The simulation results show that the chosen depth functions are valuable for the water balance calculation of mire ecotopes with a fully developed akrotelm like ombro- and mesotrophic peatlands. For degenerated peat soil or regenerating mires it is necessary to improve the model and the parameter calibration, especially the depth functions, with additional measured data in different peatlands.

  7. Investigating the impact of Lake Agassiz drainage routes on the 8.2 ka cold event with a climate model

    NASA Astrophysics Data System (ADS)

    Li, Y.-X.; Renssen, H.; Wiersma, A. P.; Törnqvist, T. E.

    2009-08-01

    The 8.2 ka event is the most prominent abrupt climate change in the Holocene and is often believed to result from catastrophic drainage of proglacial lakes Agassiz and Ojibway (LAO) that routed through the Hudson Bay and the Labrador Sea into the North Atlantic Ocean, and perturbed Atlantic meridional overturning circulation (MOC). One key assumption of this triggering mechanism is that the LAO freshwater drainage was dispersed over the Labrador Sea. Recent data, however, show no evidence of lowered δ18O values, indicative of low salinity, from the open Labrador Sea around 8.2 ka. Instead, negative δ18O anomalies are found close to the east coast of North America, extending as far south as Cape Hatteras, North Carolina, suggesting that the freshwater drainage may have been confined to a long stretch of continental shelf before fully mixing with North Atlantic Ocean water. Here we conduct a sensitivity study that examines the effects of a southerly drainage route on the 8.2 ka event with the ECBilt-CLIO-VECODE model. Hosing experiments of four routing scenarios, where freshwater was introduced to the Labrador Sea in the northerly route and to three different locations along the southerly route, were performed to investigate the routing effects on model responses. The modeling results show that a southerly drainage route is possible but generally yields reduced climatic consequences in comparison to those of a northerly route. This finding implies that more freshwater would be required for a southerly route than for a northerly route to produce the same climate anomaly. The implicated large amount of LAO drainage for a southerly routing scenario is in line with a recent geophysical modelling study of gravitational effects on sea-level change associated with the 8.2 ka event, which suggests that the volume of drainage might be larger than previously estimated.

  8. Investigating the impact of Lake Agassiz drainage routes on the 8.2 ka cold event with climate modeling

    NASA Astrophysics Data System (ADS)

    Li, Y.-X.; Renssen, H.; Wiersma, A. P.; Törnqvist, T. E.

    2009-03-01

    The 8.2 ka event is the most prominent abrupt climate change in the Holocene and is widely believed to result from catastrophic drainage of proglacial lakes Agassiz and Ojibway (LAO) that routed through the Hudson Bay and the Labrador Sea into the North Atlantic Ocean, and perturbed Atlantic meridional overturning circulation (MOC). One key assumption of this triggering mechanism is that the LAO freshwater drainage was spread over the Labrador Sea. Recent data, however, show no evidence of lowered δ18O values from the open Labrador Sea around 8.2 ka. Instead, negative δ18O anomalies are found close to the east coast of North America, extending as far south as Cape Hatteras, North Carolina, suggesting that the freshwater drainage was probably confined to a long stretch of continental shelf before fully mixing with North Atlantic Ocean water. Here we conduct a sensitivity study that examines the effects of this southerly drainage route on the 8.2 ka event with the ECBilt-CLIO-VECODE model. Hosing experiments of four different routing scenarios, where freshwater was introduced to the Labrador Sea in the northerly route (R1) and to three different locations (Grand Banks - R2, George Bank - R3, and Cape Hatteras - R4) on the southerly route, were performed with 0.45 m sea-level equivalent (SLE), 0.90 m SLE, and 1.35 m SLE of freshwater introduced over 5 years to investigate the routing effects on model responses. The modelling results show that a southerly drainage route is plausible but generally yields reduced climatic consequences in comparison to those of a northerly route. This finding implies that more freshwater would be required for a southerly route than for a northerly route to produce the same climate anomaly.

  9. The effects of acid deposition on sulfate reduction and methane production in peatlands

    NASA Technical Reports Server (NTRS)

    Murray, Georgia L.; Hines, Mark E.; Bayley, Suzanne E.

    1992-01-01

    Peatlands, as fens and bods, make up a large percentage of northern latitude terrestrial environments. They are organic rich and support an active community of anaerobic bacteria, such as methanogenic and sulfate-reducing bacteria. The end products of these microbial activities, methane and hydrogen sulfide, are important components in the global biogeochemical cycles of carbon and sulfur. Since these two bacterial groups compete for nutritional substrates, increases in sulfate deposition due to acid rain potentially can disrupt the balance between these processes leading to a decrease in methane production and emission. This is significant because methane is a potent greenhouse gas that effects the global heat balance. A section of Mire 239 in the Experimental Lakes Area, in Northwestern Ontario, was artificially acidified and rates of sulfate reduction and methane production were measured with depth. Preliminary results suggested that methane production was not affected immediately after acidification. However, concentrations of dissolved methane decreased and dissolved sulfide increased greatly after acidification and both took several days to recover. The exact mechanism for the decrease in methane was not determined. Analyses are under way which will be used to determine rates of sulfate reduction. These results will be available by Spring and will be discussed.

  10. Carbon dynamics in boreal peatlands of the Yenisey region, western Siberia

    NASA Astrophysics Data System (ADS)

    Schulze, E. D.; Lapshina, E.; Filippov, I.; Kuhlmann, I.; Mollicone, D.

    2015-12-01

    Here we investigate the vegetation history and peat accumulation at the eastern boarder of the West Siberian Plain, near the Yenisey River, south of permafrost. In this region, peat started to accumulate 15 000 years ago as gyttja of shallow lakes in ancient river valleys. This peat is older than previously reported, mainly due to separating particulate organic carbon (POC) from dissolved organic carbon (DOC), which was 1900-6500 years younger than POC. The probability of finding peat layers older than 12 000 years is about 2 %. Peat accumulated as fen peat at a constant rate of 0.2 mm yr-1 and 0.01 kg C m-2 yr-1. The accumulation was higher in ancient river valley environments. Over the last 2000 years these bogs changed into Sphagnum mires which have accumulated up to about 0.1 kg C m-2 yr-1 until present. The long-lasting fen stage, which makes the Yenisey bogs distinct from the western Siberian bogs, is discussed as a consequence of the local hydrology. The high accumulation rate of peat in unfrozen mires is taken as an indication that thawing of permafrost peat may also change northern peatlands into long-lasting carbon sinks.

  11. Peatland Carbon Dynamics on the North Slope of Alaska During the Holocene: The Role of Climate, Sea Ice, and Buried Peat

    NASA Astrophysics Data System (ADS)

    Yu, Zicheng; Massa, Charly; Cleary, Kathleen; Jones, Benjamin; Grosse, Guido

    2014-05-01

    Our recent and ongoing data syntheses indicate that peatlands accumulated more carbon (C) during past warm climate intervals in the circum-Arctic region, including Alaska. In particular, peak C accumulations have been observed during the Holocene Thermal Maximum (HTM) in the early Holocene when summer insolation was higher. However, we do not know the regional patterns and impacts of sea-ice change on Holocene peat C accumulation, especially around the Arctic Ocean where increased vegetation productivity has already been linked to sea ice declines in recent decades. Here we review Holocene peatland and tundra C accumulation records on the North Slope, along with our preliminary results, to investigate spatiotemporal pattern of C accumulation and the possible role of sea-ice change. As in many other northern high-latitude regions, most peatlands on the North Slope initiated in the early Holocene. Several discontinuous and low-resolution peat accumulation records from the region appear to show high accumulation rates or high C content in the early Holocene. In addition, we note that many peatlands that existed during the earlier Holocene on the North Slope have disappeared and are presently covered by mineral soils under tundra or eolian sandy deposits, indicating that current peatland extent is only a fraction of early Holocene extent. In contrast to highest C accumulation rates in the early Holocene, our preliminary results from a 70-cm-long peat core (lat. 70.71 N; long. 153.87 W) from northwest Teshekpuk Lake, near the Teshekpuk Lake Observatory on the Arctic Coastal Plain, about 10 km from the Arctic Ocean, shows a very different pattern. The highest C accumulation of 12.7 gC/m2/yr is observed after 2.9 ka, much higher than the rate of 3.8 gC/m2/yr at 8.1-2.9 ka. Furthermore, the period with high C rates after 2.9 ka at this site was dominated by well-preserved peat mosses (Sphagnum) and with abundant leaf fragments, likely from dwarf birch (Betula nana). This

  12. Holocene carbon dynamics and radiative forcing of three different types of peatlands in Finland

    NASA Astrophysics Data System (ADS)

    Mathijssen, Paul; Väliranta, Minna; Lohila, Annalea; Minkkinen, Kari; Tuittila, Eeva-Stiina; Tuovinen, Juha-Pekka; Korrensalo, Aino

    2016-04-01

    Peatlands contain approximately a third of all soil carbon globally and as they exchange carbon dioxide (CO2) and methane (CH4) copiously with the atmosphere, changes in peatland carbon budgets have a large impact on the global carbon balance and the concentration of greenhouse gasses in the atmosphere. There has been a growing interest in reconstructing and linking peatland carbon dynamics to past climate variations, because quantitative reconstructions can be used as a basis for future carbon balance predictions. In order to increase our understanding on peatland development and response patterns we quantitatively reconstructed Holocene carbon dynamics of three different peatlands in Finland: a subarctic fen, a boreal peatland complex and a boreal managed pine bog. Several cores from each peatland were investigated. The peatlands showed distinct successional pathways, which were sometimes triggered by fires. Successional stages were partly reflected in carbon accumulation patterns. Sometimes variations in carbon accumulation rates coincided with autogenic changes in peat type and vegetation, but accumulation rates were also related to the large-scale Holocene climate phases. However, Holocene climate changes as such did not seem to result in changes in the peat plant species composition. The mid-Holocene warm and dry climate conditions reduced the carbon accumulation in the subarctic fen and in the fen part of the boreal peatland complex, but when the peatland was in bog phase this effect was not visible. Some bog cores showed a clear increase in carbon accumulation after fen-bog transition, but the pattern was not unanimous. In addition to carbon accumulation, we estimated past CH4 emissions for each peatland respectively by applying different methods and by utilising the established current vegetation-CH4 emission relationship. The reconstructions showed that CH4 emissions always decreased during bog stages, but that the CH4 emissions played a major role in the

  13. Can Decommissioned Oil Pads in Boreal Alberta BE Reclaimed to Carbon Accumulating Peatlands?

    NASA Astrophysics Data System (ADS)

    Wieder, R.; Vitt, D. H.; Mowbray, S.

    2010-12-01

    In northern Alberta where peatland ecosystems are a dominant landscape feature, construction of oil drilling pads and access roads is a major disturbance. Reclamation of decommissioned oil pads has been hampered by the lack of research. At two decommissioned oil pads at Shell Oil’s Peace River Complex (northeastern Alberta), initially constructed in a bog/fen complex, we established a field experiment to assess reclamation approaches that could lead to a system reflecting undisturbed peatland structure (vegetation composition) and function (net carbon accumulation). In the fall of 2007, mineral soil was removed from two decommissioned pads in areas approximately 100-m x 30-m creating a mineral surface at or near the surrounding bog water table level. We established the following treatments: pad (fertilized vs. unfertilized); water table position (at and 5-cm above the surrounding bog water level); texture (tilling soil amendments into the mineral soil or not); amendment (controls; commercial peat, peat that had been stockpiled in a farmer’s field; landscape fabric; slough hay (native species hay from harvested from local farms), aspen wood chips); planting (in 1-m x 1-m subplots within 2-m x 2-m amendment plots: no planting, 9 Carex aquatilis plants, 5 C. aquatilis and 4 Salix lutea plants; 3 C. aquatilis, 3 S. lutea and 3 Larix laricina seedlings). Treatments were nested (planting within amendment, within texture, within water table level, within pad), with 6 replicate 2-m x 2-m plots of each amendment within each pad x texture x water level combination. Net CO2 exchange was quantified under a range of PAR conditions from full sunlight to complete darkness in each 1-m x 1-m planting subplot repeatedly during the summers of 2008, 2009 and 2010 using closed chambers and infrared gas analyzers. Both dark respiration and maximum net ecosystem production (NEPSAT; net CO2 sequestration when PAR>1000 μmol m-2 s-1) exhibited year x planting interactions (p<0.0001 and

  14. The effective oxidation state of a peatland

    NASA Astrophysics Data System (ADS)

    Worrall, Fred; Clay, Gareth D.; Moody, Catherine S.; Burt, Tim P.; Rose, Rob

    2016-01-01

    The oxidative ratio (OR) of the organic matter of the terrestrial biosphere is a key parameter in the understanding of the magnitude of the carbon sink represented both by the terrestrial biosphere and by the global oceans. However, no study has considered the oxidation state of all the organic pools and fluxes within one environment. In this study all organic matter pathways (dissolved organic matter, particulate organic matter, CO2, and CH4) were measured within an upland peat ecosystem in northern England. The study showed the following: (1) The peat soil of ecosystem was accumulating oxygen at a rate of between -16 and -73 t O km-2 yr-1; (2) Although there was no significant variation in oxidation state in the peat profile, there was a significant increase in degree of unsaturation with depth; (3) The dissolved organic matter leaving the ecosystem was significantly more oxidized than the other carbon pools analyzed while the particulate organic matter was not significantly different from the peat soil profile; and (4) Assuming that all carbon flux from the site was as CO2, the OR of the ecosystem was 1.07; when the nature and speciation of the release pathways were considered, the ecosystem OR was 1.04. At the global scale, correcting for the speciation of carbon fluxes means that the annual global fluxes of carbon to land = 1.49 ± 0.003 Gt C/yr and to the oceans = 2.01 ± 0.004 Gt C/yr.

  15. Temporal and spatial aspects of peatland initiation following deglaciation in North America

    NASA Astrophysics Data System (ADS)

    Gorham, Eville; Lehman, Clarence; Dyke, Arthur; Janssens, Joannes; Dyke, Lawrence

    2007-02-01

    A set of simple ecological models accounts well for the cumulative initiation of peatlands throughout North America in relation to glacial retreat. The most parsimonious form incorporates, first, a delay term to account for the lag during which newly deglaciated land became suitable for peatland initiation and, second, an intrinsic rate of initiation related to the probability of migration and establishment of plant propagules from elsewhere. The goodness of fit of the models, based on 1680 basal-peat dates throughout the continent, allows projection of past trends into the future. Factors contributing to the lag of about 4000 years between deglaciation and peatland initiation are suggested and data on colonization of deglaciated land by beavers (known to initiate peatlands) are presented. The rate of peatland initiation peaked between 7000 and 8000 years ago, but remains appreciable today. A marked depression of peatland initiation (8360-8040 BP) interrupted the peak rate. The time of the interruption matches the 8200 BP cold-dry event recorded in Greenland ice cores, and suggests that this event caused a substantial, continent-wide depression of an important ecosystem function, i.e., carbon sequestration from the atmosphere by peat deposition. Spontaneous initiation of new peatlands is projected to continue for millennia to come.

  16. Greenhouse gas balances in low-productive drained boreal peatlands - is climate-friendly management possible?

    NASA Astrophysics Data System (ADS)

    Ojanen, Paavo; Minkkinen, Kari; Heikkinen, Tiina; Penttilä, Timo

    2016-04-01

    Five million hectares of peatland has been drained for forestry in Finland. About 20% of that, i.e. one million hectares, has been estimated to be so low-productive that the profitability of keeping them in forestry is questionable. At the same time, drainage has introduced changes in the ecosystem functions of these peatlands, including fluxes of greenhouse gases. Options to manage such peatlands include for example 1) no measures, i.e. leaving the drained peatlands as they are 2) increasing intensity by e.g. repetitive fertilisations and 3) restoration back to functional peatlands. Here we estimate the greenhouse gas impacts of these three management options. We collected GHG and organic carbon flux data from 50 low-productive peatlands under these management options over two years 2014-2015. Gas fluxes (CO2, CH4, N2O) were measured with closed chambers. Litter production rates of different plants above and below ground were estimated using litter traps (trees), biomass sampling (roots), through-grow nets (mosses), allometric biomass models (other vasculars) and published turnover rates (roots, other vasculars). Characteristics for estimating tree stand biomass increment were measured at each site from circular sample plots. In this presentation we will estimate the GHG impacts for the different management options, and aim to find the most climate-friendly options for the management of low-productive peatlands in the short and long term. This work was funded by Life+ LIFE12/ENV/FI/150.

  17. The distribution and amount of carbon in the largest peatland complex in Amazonia

    NASA Astrophysics Data System (ADS)

    Draper, Frederick C.; Roucoux, Katherine H.; Lawson, Ian T.; Mitchard, Edward T. A.; Honorio Coronado, Euridice N.; Lähteenoja, Outi; Torres Montenegro, Luis; Valderrama Sandoval, Elvis; Zaráte, Ricardo; Baker, Timothy R.

    2014-12-01

    Peatlands in Amazonian Peru are known to store large quantities of carbon, but there is high uncertainty in the spatial extent and total carbon stocks of these ecosystems. Here, we use a multi-sensor (Landsat, ALOS PALSAR and SRTM) remote sensing approach, together with field data including 24 forest census plots and 218 peat thickness measurements, to map the distribution of peatland vegetation types and calculate the combined above- and below-ground carbon stock of peatland ecosystems in the Pastaza-Marañon foreland basin in Peru. We find that peatlands cover 35 600 ± 2133 km2 and contain 3.14 (0.44-8.15) Pg C. Variation in peat thickness and bulk density are the most important sources of uncertainty in these values. One particular ecosystem type, peatland pole forest, is found to be the most carbon-dense ecosystem yet identified in Amazonia (1391 ± 710 Mg C ha-1). The novel approach of combining optical and radar remote sensing with above- and below-ground carbon inventories is recommended for developing regional carbon estimates for tropical peatlands globally. Finally, we suggest that Amazonian peatlands should be a priority for research and conservation before the developing regional infrastructure causes an acceleration in the exploitation and degradation of these ecosystems.

  18. Peatland simulator connecting drainage, nutrient cycling, forest growth, economy and GHG efflux in boreal and tropical peatlands

    NASA Astrophysics Data System (ADS)

    Lauren, Ari; Hökkä, Hannu; Launiainen, Samuli; Palviainen, Marjo; Lehtonen, Aleksi

    2016-04-01

    Forest growth in peatlands is nutrient limited; principal source of nutrients is the decomposition of organic matter. Excess water decreases O2 diffusion and slows down the nutrient release. Drainage increases organic matter decomposition, CO2 efflux, and nutrient supply, and enhances the growth of forest. Profitability depends on costs, gained extra yield and its allocation into timber assortments, and the rate of interest. We built peatland simulator Susi to define and parameterize these interrelations. We applied Susi-simulator to compute water and nutrient processes, forest growth, and CO2 efflux of forested drained peatland. The simulator computes daily water fluxes and storages in two dimensions for a peatland forest strip located between drainage ditches. The CO2 efflux is made proportional to peat bulk density, soil temperature and O2 availability. Nutrient (N, P, K) release depends on decomposition and peat nutrient content. Growth limiting nutrient is detected by comparing the need and supply of nutrients. Increased supply of growth limiting nutrient is used to quantify the forest growth response to improved drainage. The extra yield is allocated into pulpwood and sawlogs based on volume of growing stock. The net present values of ditch cleaning operation and the gained extra yield are computed under different rates of interest to assess the profitability of the ditch cleaning. The hydrological sub-models of Susi-simulator were first parameterized using daily water flux data from Hyytiälä SMEAR II-site, after which the predictions were tested against independent hydrologic data from two drained peatland forests in Southern Finland. After verification of the hydrologic model, the CO2 efflux, nutrient release and forest growth proportionality hypothesis was tested and model performance validated against long-term forest growth and groundwater level data from 69 forested peatland sample plots in Central Finland. The results showed a clear relation between

  19. Summer moisture balance from peatland water table reconstructions for the last 1100 years from North America and Europe

    NASA Astrophysics Data System (ADS)

    Gallego-Sala, A. V.; Brewer, S.; Charman, D.; Blundell, A.; Booth, R. K.; Clifford, M. J.; Friedlingstein, P.; Garneau, M.; Hohl, V.; Lamarre, A.; Lamentowicz, M.; Magnan, G.; Mauquoy, D.; Swindles, G. T.; van Bellen, S.

    2013-12-01

    The last millennium may have been characterized by strong regional variations in precipitation, as evidenced by the megadrought of south west North America during the Medieval Climate Anomaly (MCA), for example. Here we present the first large regional scale peatland hydrology reconstruction for eastern North America and western Europe reflecting warm-season moisture balance for the last 1100 years. We use testate amoebae analysis of forty-three mires distributed over Europe and central and eastern North America to reconstruct changes in water table during the last 1100 years. The chronology of each peat profile was determined individually by radiocarbon and other dating techniques and then reconstructions were combined with all other cores. The regional palaeohydrology reconstructions were assembled using a novel method to include both chronological uncertainties derived from the radiocarbon age-depth model and uncertainties linked to the quantification of the proxies. We present hydrological trends for each region separately and overall with associated uncertainties. We compare these with climate model outputs in the form of soil moisture, warm-season precipitation and reconstructed PDSI from tree rings for Northern America. The hydrological reconstructions suggests that it was relatively dry during the MCA and became wetter during the Little Ice Age (LIA) in both Europe and central-eastern North America. The MCA drying in North America was more extreme and shows greater centennial scale variability than in Europe. LIA wetness was probably more extreme and more hydrologically unstable in Europe. Recent (last 100 years) trends are to drier conditions in both regions and peatlands in Europe are drier than they have been at any time during the last 1100 years.

  20. Modeling impacts of changes in temperature and water table on C gas fluxes in an Alaskan peatland

    NASA Astrophysics Data System (ADS)

    Deng, Jia; Li, Changsheng; Frolking, Steve

    2015-07-01

    Northern peatlands have accumulated a large amount of organic carbon (C) in their thick peat profile. Climate change and associated variations in soil environments are expected to have significant impacts on the C balance of these ecosystems, but the magnitude is still highly uncertain. Verifying and understanding the influences of changes in environmental factors on C gas fluxes in biogeochemical models are essential for forecasting feedbacks between C gas fluxes and climate change. In this study, we applied a biogeochemical model, DeNitrification-DeComposition (DNDC), to assess impacts of air temperature (TA) and water table (WT) on C gas fluxes in an Alaskan peatland. DNDC was validated against field measurements of net ecosystem exchange of CO2 (NEE) and CH4 fluxes under manipulated surface soil temperature and WT conditions in a moderate rich fen. The validation demonstrates that DNDC was able to capture the observed impacts of the manipulations in soil environments on C gas fluxes. To investigate responses of C gas fluxes to changes in TA and soil water condition, we conducted a series of simulations with varying TA and WT. The results demonstrate that (1) uptake rates of CO2 at the site were reduced by either too colder or warmer temperatures and generally increased with increasing soil moisture; (2) CH4 emissions showed an increasing trend as TA increased or WT rose toward the peat surface; and (3) the site could shift from a net greenhouse gas (GHG) sink into a net GHG source under some warm and/or dry conditions. A sensitivity analysis evaluated the relative importance of TA and WT to C gas fluxes. The results indicate that both TA and WT played important roles in regulating NEE and CH4 emissions and that within the investigated ranges of the variations in TA and WT, changes in WT showed a greater impact than changes in TA on NEE, CH4 fluxes, and net C gas fluxes at the study fen.

  1. Fractionation of (137)Cs and Pu in natural peatland.

    PubMed

    Mihalík, Ján; Bartusková, Miluše; Hölgye, Zoltán; Ježková, Tereza; Henych, Ondřej

    2014-08-01

    High Cs-137 concentrations in plants growing on peatland inspired us to investigate the quantity of its bioavailable fraction in natural peat. Our investigation aims to: a) estimate the quantity of bioavailable Cs-137 and Pu present in peat, b) verify the similarity of Cs-137 and K-40 behaviours, and c) perform a quantification of Cs-137 and Pu transfer from peat to plants. We analysed the vertical distribution of Cs-137 and Pu isotopes in the peat and their concentrations in plants growing on these places. Bioavailability of radionuclides was investigated by sequential extraction. Sequential analyses revealed that it was the upper layer which contained the majority of Cs-137 in an available form while deeper layers retained Cs-137 in immobile fractions. We can conclude that 18% of all Cs-137 in the peat is still bioavailable. Despite of the low quantity of bioavailable fraction of Cs-137 its transfer factor reached extremely high values. In the case of Pu, 64% of its total amount was associated with fulvic/humic acids which resulted in the high transfer factor from peat to plants. 27 years after the Chernobyl nuclear accident, the significant part of radionuclides deposited in peatland is still bioavailable. PMID:24631917

  2. Global vulnerability of peatlands to fire and carbon loss

    NASA Astrophysics Data System (ADS)

    Turetsky, Merritt R.; Benscoter, Brian; Page, Susan; Rein, Guillermo; van der Werf, Guido R.; Watts, Adam

    2015-01-01

    Globally, the amount of carbon stored in peats exceeds that stored in vegetation and is similar in size to the current atmospheric carbon pool. Fire is a threat to many peat-rich biomes and has the potential to disturb these carbon stocks. Peat fires are dominated by smouldering combustion, which is ignited more readily than flaming combustion and can persist in wet conditions. In undisturbed peatlands, most of the peat carbon stock typically is protected from smouldering, and resistance to fire has led to a build-up of peat carbon storage in boreal and tropical regions over long timescales. But drying as a result of climate change and human activity lowers the water table in peatlands and increases the frequency and extent of peat fires. The combustion of deep peat affects older soil carbon that has not been part of the active carbon cycle for centuries to millennia, and thus will dictate the importance of peat fire emissions to the carbon cycle and feedbacks to the climate.

  3. Opportunities for reducing greenhouse gas emissions in tropical peatlands

    PubMed Central

    Murdiyarso, D.; Hergoualc’h, K.; Verchot, L. V.

    2010-01-01

    The upcoming global mechanism for reducing emissions from deforestation and forest degradation in developing countries should include and prioritize tropical peatlands. Forested tropical peatlands in Southeast Asia are rapidly being converted into production systems by introducing perennial crops for lucrative agribusiness, such as oil-palm and pulpwood plantations, causing large greenhouse gas (GHG) emissions. The Intergovernmental Panel on Climate Change Guidelines for GHG Inventory on Agriculture, Forestry, and Other Land Uses provide an adequate framework for emissions inventories in these ecosystems; however, specific emission factors are needed for more accurate and cost-effective monitoring. The emissions are governed by complex biophysical processes, such as peat decomposition and compaction, nutrient availability, soil water content, and water table level, all of which are affected by management practices. We estimate that total carbon loss from converting peat swamp forests into oil palm is 59.4 ± 10.2 Mg of CO2 per hectare per year during the first 25 y after land-use cover change, of which 61.6% arise from the peat. Of the total amount (1,486 ± 183 Mg of CO2 per hectare over 25 y), 25% are released immediately from land-clearing fire. In order to maintain high palm-oil production, nitrogen inputs through fertilizer are needed and the magnitude of the resulting increased N2O emissions compared to CO2 losses remains unclear. PMID:21081702

  4. Low impact of dry conditions on the CO2 exchange of a Northern-Norwegian blanket bog

    NASA Astrophysics Data System (ADS)

    Lund, Magnus; Bjerke, J. W.; Drake, B. G.; Engelsen, O.; Hansen, G. H.; Parmentier, F. J. W.; Powell, T. L.; Silvennoinen, H.; Sottocornola, M.; Tømmervik, H.; Weldon, S.; Rasse, D. P.

    2015-02-01

    Northern peatlands hold large amounts of organic carbon (C) in their soils and are as such important in a climate change context. Blanket bogs, i.e. nutrient-poor peatlands restricted to maritime climates, may be extra vulnerable to global warming since they require a positive water balance to sustain their moss dominated vegetation and C sink functioning. This study presents a 4.5 year record of land-atmosphere carbon dioxide (CO2) exchange from the Andøya blanket bog in northern Norway. Compared with other peatlands, the Andøya peatland exhibited low flux rates, related to the low productivity of the dominating moss and lichen communities and the maritime settings that attenuated seasonal temperature variations. It was observed that under periods of high vapour pressure deficit, net ecosystem exchange was reduced, which was mainly caused by a decrease in gross primary production. However, no persistent effects of dry conditions on the CO2 exchange dynamics were observed, indicating that under present conditions and within the range of observed meteorological conditions the Andøya blanket bog retained its C uptake function. Continued monitoring of these ecosystem types is essential in order to detect possible effects of a changing climate.

  5. A decade of continuous NEE measurements at a Scottish peatland

    NASA Astrophysics Data System (ADS)

    Helfter, Carole; Campbell, Claire; Coyle, Mhairi; Anderson, Margaret; Drewer, Julia; Levy, Peter; Famulari, Daniela; Twigg, Marsailidh; Skiba, Ute; Billett, Michael; Dinsmore, Kerry; Nemitz, Eiko; Sutton, Mark

    2013-04-01

    Eddy-covariance measurements of carbon dioxide (CO2) fluxes have been running continuously at the Auchencorth Moss peatland site in Scotland (55o47'32N, 3o14'35W, 267 m a.s.l.) since the spring of 2002 which makes this study one of the longest ones to date on a peatland system. Auchencorth Moss is a low-lying, ombrotrophic peatland situated ca. 20 km south-west of Edinburgh. Peat depth ranges from <0.5 m to >0.5 m and the site has a mean annual precipitation of 1155 mm. The open moorland site has an extensive uniform fetch of blanket bog to the south, west and north. The vegetation present within the flux measurement footprint comprises mixed grass species, heather and substantial areas of moss species (Sphagnum spp. and Polytrichum spp.). The eddy-covariance system consists of a Licor 7000 closed-path infrared gas analyser operating at 10 Hz for the simultaneous measurement of carbon dioxide and water vapour and of a Gill Windmaster Pro ultrasonic anemometer, operating at 20 Hz, and mounted atop a 3 m mast. The effective measurement height is 3.5 m with a vertical separation of 20 cm between the anemometer and the inlet of the sampling line. Air is sampled at 20 litres per minute through a 40 m long Dekabon line (internal diameter 4 mm). In addition to eddy-covariance measurements, the site is equipped with a weather station, soil temperature measurements, total solar radiation and photosynthetically active radiation (PAR) sensors, a tipping bucket for rainfall and, since April 2007, water table depth has been recorded at half-hourly interval. On an annual basis, the peatland at Auchencorth Moss has consistently been a net sink of CO2 in the study period 2002-2012 with a mean net ecosystem exchange (NEE) of - 69.1 ± 33.6 g C-CO2 m-2 yr-1. This value is at the high end of other recent studies as is the inter-annual range of NEE (-31.4 to -135.9 g C-CO2 m-2 yr-1). Inter-annual variations in NEE are significant and strongly correlated to the length of the growing

  6. HONO (nitrous acid) emissions from acidic northern soils

    NASA Astrophysics Data System (ADS)

    Maljanen, Marja; Yli-Pirilä, Pasi; Joutsensaari, Jorma; Sulassaari, Sirkka; Martikainen, Pertti J.

    2014-05-01

    The photolysis of HONO (nitrous acid) is an important source of OH radical, the key oxidizing agent in the atmosphere, contributing also to removal of atmospheric methane (CH4), the second most important greenhouse gas after carbon dioxide (CO2). There are missing sources of HONO when considering the chemical reactions in the atmosphere. Soil could be such a missing source. Emissions of HONO from soils studied in laboratory incubations have been recently reported. The soil-derived HONO has been connected to soil nitrite (NO2-) and a study with an ammonium oxidizing bacterium has shown that HONO could be produced in ammonium oxidation. Our hypothesis was that boreal acidic soils with high nitrification activity could be important sources of HONO. We selected a range of dominant northern acidic soils and showed in microcosm experiments that soils which have the highest nitrous oxide (N2O) and nitric oxide (NO) emissions (drained peatlands) also have the highest HONO production rates. The emissions of HONO are thus linked to nitrogen cycle processes. In contrast to drained peatlands, natural peatlands with high water table and boreal coniferous forests on mineral soils with low nitrification capacity had low HONO emissions. It is known that in natural peatlands with high water table and in boreal coniferous forest soils, low nitrification activity (microbial production of nitrite and nitrate) limits their N2O production. Low nitrification rate and low availability of nitrite in these soils are the likely reasons for their low HONO production rates. We studied the origin of HONO in one drained peat soil by inhibiting nitrification with acetylene. Acetylene blocked NO emissions but did not affect HONO or N2O emissions, thus ammonium oxidation is not the direct mechanism for the HONO emission in this soil. It is still an open question if HONO originates directly from some microbial process like ammonium oxidation or chemically from nitrite produced in microbial processes.

  7. The diversity of microfungi in peatlands originated from the White Sea.

    PubMed

    Grum-Grzhimaylo, Olga A; Debets, Alfons J M; Bilanenko, Elena N

    2016-01-01

    The diversity of culturable filamentous microfungi in peat and sediments of four peatlands at the coastal zone of Kandalaksha Bay of the White Sea (Murmansk region, Russia) was studied by culture methods on standard and selective media. Annually 100 samples were collected from the bogs 2007-2010. Based on morphological, molecular markers and cultural features, 211 taxa were identified. Fungal communities observed at the peatlands were influenced mostly by their sea origin. We discovered a large difference between fungal communities from the peat and the sediments of the peatlands. In contrast to the sediments, the fungal community of the peat was found to be consistent throughout sampling sites. Fungi with specific ecophysiology, such as Sphagnum-decomposing species (Oidiodendron griseum, O. tenuissimum. Penicillium spinulosum, P. thomii, Talaromyces funiculosus), psychrotolerant and associated with insects species (Pseudogymnoascus pannorum, Tolypocladium spp.), typical marine species (Acremonium spp.) were found. In addition, different types of sterile mycelia were characteristic for the researched peatlands. PMID:26742584

  8. Carbon storage and release in Indonesian peatlands since the last deglaciation

    NASA Astrophysics Data System (ADS)

    Dommain, René; Couwenberg, John; Glaser, Paul H.; Joosten, Hans; Suryadiputra, I. Nyoman N.

    2014-08-01

    Peatlands have been recognised as globally important carbon sinks over long timescales that produced a global, net-climatic cooling effect over the Holocene. However, little is known about the role of tropical peatlands in the global carbon cycle. We therefore determine the past rates of carbon storage and release in the Indonesian peatlands of Kalimantan and Sumatra - the largest global concentration of tropical peatlands - since 20 ka (kiloannum before present). Using a novel GIS (geographic information system) approach we provide a spatially-explicit reconstruction of peatland expansion in a series of paleogeographic maps. Sea-level change is identified as the principal driver for peatland formation and expansion in western Indonesia as it controls both atmospheric moisture supply and the hydrological gradient on the islands. Initiation of inland peatlands in Kalimantan was coupled to periods of rapid deglacial sea-level rise with rates of over 10 mm yr-1 whereas coastal peatlands could only form after 7 ka when the rate of sea-level rise had slowed to 2.4 mm yr-1. Falling sea levels after 5 ka led to rapid peatland expansion in coastal lowlands and a doubling of the total peatland area in western Indonesia to 131,500 km2 between 2.3 ka and 0 ka. As a result of slow peatland expansion from 15 to 6 ka and rapid expansion afterwards the rate of annual carbon storage of all western Indonesian peatlands remained <1 Tg C yr-1 until 6 ka and then increased to 7.2 Tg C yr-1 by 0 ka. Associated with this rise in carbon storage was an exponential growth of the peat carbon pool from 0.01 Pg C by 15 ka to 23.2 Pg C at present, of which 70% is stored in coastal peatlands. In inland Kalimantan peatlands, falling sea levels together with increased El Niño activity induced an annual carbon release of 0.15 Tg C yr-1 from aerobic peat decay since 2 ka. Cumulative carbon losses from anaerobic decomposition do not seem to limit peat bog growth in the tropical peatlands of

  9. Influence of Water Table Depth on Pore Water Chemistry and Trihalomethane Formation Potential in Peatlands.

    PubMed

    Gough, Rachel; Holliman, Peter J; Fenner, Nathalie; Peacock, Mike; Freeman, Christopher

    2016-02-01

    Drained peatland catchments are reported to produce more colored, dissolved organic carbon (DOC)-rich water, presenting problems for potable water treatment. The blocking of peatland drainage ditches to restore the water table is increasingly being considered as a strategy to address this deterioration in water quality. However, the effect of ditch blocking on the potential of DOC to form trihalomethanes (THMs) has not been assessed. In this study, the effect of peat rewetting on pore water DOC concentration and characteristics (including THM formation potential [THMFP]) was assessed over 12 months using peat cores collected from two drained peatland sites. The data show little evidence of differences in DOC concentration or characteristics between the different treatments. The absence of any difference in the THMFP of pore water between treatments suggests that, in the short term at least, ditch blocking may not have an effect on the THMFP of waters draining peatland catchments. PMID:26803099

  10. Untangling climate signals from autogenic changes in long-term peatland development

    NASA Astrophysics Data System (ADS)

    Morris, Paul J.; Baird, Andy J.; Young, Dylan M.; Swindles, Graeme T.

    2015-12-01

    Peatlands represent important archives of Holocene paleoclimatic information. However, autogenic processes may disconnect peatland hydrological behavior from climate and overwrite climatic signals in peat records. We use a simulation model of peatland development driven by a range of Holocene climate reconstructions to investigate climate signal preservation in peat records. Simulated water-table depths and peat decomposition profiles exhibit homeostatic recovery from prescribed changes in rainfall, whereas changes in temperature cause lasting alterations to peatland structure and function. Autogenic ecohydrological feedbacks provide both high- and low-pass filters for climatic information, particularly rainfall. Large-magnitude climatic changes of an intermediate temporal scale (i.e., multidecadal to centennial) are most readily preserved in our simulated peat records. Simulated decomposition signals are offset from the climatic changes that generate them due to a phenomenon known as secondary decomposition. Our study provides the mechanistic foundations for a framework to separate climatic and autogenic signals in peat records.

  11. Microbial enzyme activities of peatland soils in south central Alaska lowlands

    EPA Science Inventory

    Microbial enzyme activities related to carbon and nutrient acquisition were measured on Alaskan peatland soils as indicators of nutrient limitation and biochemical sustainability. Peat decomposition is mediated by microorganisms and enzymes that in turn are limited by various ph...

  12. Tropical peatland carbon dynamics simulated for scenarios of disturbance and restoration and climate change

    NASA Astrophysics Data System (ADS)

    Frolking, S. E.; Warren, M.; Dai, Z.; Kurnianto, S.; Hagen, S. C.

    2015-12-01

    Tropical peatlands contain a globally significant carbon pool. Southeast Asian peatlands are being deforested, drained and burned at very high rates, mostly for conversion to industrial oil palm or pulp and paper plantations. The climate mitigation potential of tropical peatlands has gained increasing attention in recent years as persistent greenhouse gas emissions can be avoided or decreased if peatlands remain intact or are rehabilitated. In addition, peatland conservation or rehabilitation for climate mitigation also includes multiple co-benefits such as maintenance of ecosystem services, biodiversity, and air quality from reduced fire occurrence. Inventory guidelines and methodologies have only recently become available, and are based on few data from a limited number of sites. Few heuristic tools are available to evaluate the impact of management practices on carbon dynamics in tropical peatlands, and the potential climate mitigation benefits of peatland restoration. We used a process based dynamic tropical peatland model to explore the C dynamics of several peatland management trajectories represented by hypothetical scenarios, within the context of simulated 21st century climate change. All scenarios with land use, including those with optimal restoration, simulate C loss over the 21st century, with C losses ranging from 10% to essentially 100% of pre-disturbance values. Fire, either prescribed as part of a crop rotation cycle, or stochastic occurrences in sub-optimally managed degraded land can be the dominant C-loss pathway, particularly in the drier climate scenario we tested. A single 25-year oil palm rotation, with a prescribed initial burn, lost 40-50 kg C/m2, equivalent to accumulation during the previous 500 years, 10-30% of which was restored in 75 years of optimal restoration. Our results indicate that even under the most optimistic scenario of hydrological and forest restoration and the wettest climate regime, only about one-third of the carbon

  13. CO2 and CH4 fluxes of an Alpine peatland during extraordinary summer drought

    NASA Astrophysics Data System (ADS)

    Drollinger, Simon; Glatzel, Stephan

    2016-04-01

    In peatland ecosystems, plant production exceeds decomposition due to their typical characteristic of waterlogged soils leading to peatland growth and an accumulation of thick organic soil layers. As a result, peatlands constitute a major global storage of carbon (C) by storing about 612 PgC in their peat, thus representing the most space-effective C stocks of all terrestrial ecosystems, similar in magnitude as the increasing atmospheric C pool (~ 850 PgC). However, little is known about the effects of climate change on peatlands and the contribution of Alpine peatlands as a source of greenhouse gases in the course of a changing climate. It is debatable how land-use changes and ongoing degradation of Alpine peatlands affect the peatland-atmosphere C exchange. On the one hand, more C may sequester due to increased plant growth in a warmer climate, on the other hand large amounts of respired C may release as a consequence of higher temperatures and lowered peatland water table depths due to increasing evaporation rates and extending drought periods. To examine the potential effects of climate change on the peatland carbon exchange with the atmosphere, we calculated CO2 and CH4 fluxes using the eddy covariance method. The investigated ombrotrophic peatland is located on the bottom of the Styrian Enns valley at an altitude of 632 m above sea level. It is a slightly degraded pine peat bog (62 ha) with a closed peat moss cover featuring the three plant associations Pino mugo-Sphagnetum magellanici, Sphagnetum magellanici, and Caricetum limosae, according to the prevailing hydrological site conditions. During summer drought in 2015, the water level decreased from an annual average water level of -10.44 cm to -28.50 cm below surface at the centre of the peat bog. Here, we present diurnal pattern of CO2 and CH4 fluxes during an extraordinary dry summer and compare them to calculated fluxes during periods characterised by precipitation and higher peat water levels of the

  14. Effect of long-term drainage of peatland on whole-profile microbial community structure

    NASA Astrophysics Data System (ADS)

    Mpamah, Promise; Taipale, Sami; Rissanen, Antti; Biasi, Christina; Nykänen, Hannu

    2015-04-01

    Peatlands are crucial global carbon stores largely due to prevailing hydrological regime leading to higher rate of carbon input than loss. Like other changes in environmental conditions, alteration in peatland water table, which causes increased aeration in the upper layer, does not only cause a shift in this exchange rates, but leads to changes in plant species cover, litter quality as well as the niches of microbes, by affecting their functions and activities. Effects of changes in peatland hydrology are therefore complex, and play a key role in peat carbon cycles. Changed peat hydrology may especially affect the inter-play between methanogens and methanotrophs which are important members of the microbial community taking part in anaerobic/aerobic peatland carbon cycles. We provide more information on the effect of long-term (more than 33 years) changes in hydrology on the whole-peat-profile microbes, from top to bottom. We studied drained and adjacent non-drained peatlands in Lakkasuo mire complex and Lammi area of Finland, which differed in vegetation cover and management history. We focused majorly on the phospholipid fatty acids (PLFA) analysis as an indicator of the overall microbial community structure, but also used DNA analysis to mainly compare the methane oxidizing bacteria (MOB) of the different peatland types with different vegetation. Our PLFA results showed that peat mire complexes are more similar in their microbial community, within location and profiles than between locations irrespective of hydrological changes and types or vegetation covers. PLFA and DNA analysis also showed that MOB species belonging to type II were more dominant than those of type I in both locations studied. Our study also showed that long-term draining of peatlands does not change the biomass of soil microbial communities, but alters their structural or relative composition. The effect of long-term peatland drainage is mostly located at the surface. Depth gradient effects

  15. Insights from 14C into C loss pathways in degraded peatlands

    NASA Astrophysics Data System (ADS)

    Evans, Martin; Evans, Chris; Allott, Tim; Stimson, Andrew; Goulsbra, Claire

    2016-04-01

    Peatlands are important global stores of terrestrial carbon. Lowered water tables due to changing climate and direct or indirect human intervention produce a deeper aerobic zone and have the potential to enhance loss of stored carbon from the peat profile. The quasi continuous accumulation of organic matter in active peatlands means that the age of fluvial dissolved organic carbon exported from peatland systems is related to the source depth in the peat profile. Consequently 14C analysis of DOC in waters draining peatlands has the potential not only to tell us about the source of fluvial carbon and the stability of the peatland but also about the dominant hydrological pathways in the peatland system. This paper will present new radiocarbon determinations from peatland streams draining the heavily eroded peatlands of the southern Pennine uplands in the UK. These blanket peatland systems are highly degraded, with extensive bare peat and gully erosion resulting from air pollution during the industrial revolution, overgrazing, wildfire and climatic changes. Deep and extensive gullying has significantly modified the hydrology of these systems leading to local and more widespread drawdown of water table. 14C data from DOC in drainage waters are presented from two catchments; one with extensive gully erosion and the other with a combination of gully erosion and sheet erosion of the peat. At the gully eroded site DOC in drainage waters is as old as 160 BP but at the site with extensive sheet erosion dates of up to 1069 BP are amongst the oldest recorded from blanket peatland globally These data indicate significant degradation of stored carbon from the eroding peatlands. Initial comparisons of the 14C data with modelled water table for the catchments and depth-age curves for catchment peats suggests that erosion of the peat surface, allowing decomposition of exposed older organic material is a potential mechanism producing aged carbon from the eroded catchment. This

  16. Changes in vegetation, peat properties and peat accumulation in Swedish peatlands as revealed by archive data.

    NASA Astrophysics Data System (ADS)

    Schoning, Kristian; Sohlenius, Gustav

    2016-04-01

    In this investigation we have studied patterns in peat accumulation and changes in mire status since the early 1900s for two areas in Sweden. In the early 1900s the Geological Survey of Sweden collected a vast amount of peat and peatland data, including information on vegetation and land-use. We have used this archive data to evaluate changes in mire vegetation, mire wetness and surface peat properties, rates of peat accumulation, succession in young wetlands and the effects of cultivation on peatlands. In total 156 mires in an uplift area of eastern middle Sweden were included in the data-set, including both pristine mires and peatlands used for agricultural purposes. In this area new peatlands have continuously been formed during the past 7 000 years making it possible to evaluate changes in peat accumulation over time. The other study area is situated in the south Swedish Uplands where we have revisited some larger bogs. The results from our investigation show that many of the peatlands have underwent major changes since the early 1900s. In most of the small peatlands we have found important changes in vegetation where mire vegetation has been replaced by nutrient demanding and/or dry species flora while the tree stand on large mires in south Sweden have increased. In some mires humification has increased in the uppermost peat-layers and the mire surface have become drier compared to the early 1900s. In eastern middle Sweden there are indications that the peat accumulation is lower 0,5 mm/year in older peatlands compared with younger ones 1,2 mm/year, although the mire vegetation in the older peatlands is dominated by sphagnum. The peat depth of the cultivated mires in this area shows a mean decrease of 40 cm since the early 1900s.

  17. Assessing water table dynamics of peatland areas using Landsat TIR imagery

    NASA Astrophysics Data System (ADS)

    Carrión Klier, Carolina; Schuetz, Tobias; Untenecker, Johanna; Bechtold, Michel

    2016-04-01

    Water saturation conditions in peatlands are a driving factor for the emission of greenhouse gases. Thus, the identification of long-term saturation dynamics in peatland areas is a first step towards the quantification of emissions from these ecosystems. Unfortunately, information on groundwater levels is not always available on the necessary spatial or temporal resolution. Publicly available databases of remotely sensed satellite data offer ways to close this lack of information. Previous studies have shown the potential of the thermal signature of the soil surface monitored by thermal infrared imagery to derive information about subsurface hydrology. It is also known that shallow-groundwater systems as wet peatlands are less susceptible to seasonal temperature fluctuations than drained peatlands and soils with deeper groundwater. Hence, wetter peatlands will be characterized by a smoother seasonal surface temperature curve, being cooler in the summer and warmer in the winter. Due to the strong influence of the vegetation cover on thermal infrared radiative transfer, we here analyze temperature dynamics as relative differences between comparable vegetation cover in the same region. As satellite data we used remotely sensed Landsat TIR imagery. The archive of Landsat TIR imagery compiles records on a 16 days cycle since 1984. The present study seeks to use this archive to reconstruct the water saturation conditions in the peatland areas of the state of Baden-Wuerttemberg, Germany, over the last three decades. We restricted our analysis on grassland vegetation because of its predominance in the study area and its relative low vegetation height. Preliminary results for selected peatlands are 1) peatland characteristic annual patterns of TIR temperature differences, and 2) intra-annual variability over the years of available Landsat imagery within these patterns. In our presentation, we will further compare the resulting time series with available groundwater level

  18. Subsidence Rates of Drained Agricultural Peatlands in New Zealand and the Relationship with Time since Drainage.

    PubMed

    Pronger, Jack; Schipper, Louis A; Hill, Reece B; Campbell, David I; McLeod, Malcolm

    2014-07-01

    The drainage and conversion of peatlands to productive agro-ecosystems leads to ongoing surface subsidence because of densification (shrinkage and consolidation) and oxidation of the peat substrate. Knowing the ra0te of this surface subsidence is important for future land-use planning, carbon accounting, and economic analysis of drainage and pumping costs. We measured subsidence rates over the past decade at 119 sites across three large, agriculturally managed peatlands in the Waikato region, New Zealand. The average contemporary (2000s-2012) subsidence rate for Waikato peatlands was 19 ± 2 mm yr (± SE) and was significantly less ( = 0.01) than the historic rate of 26 ± 1 mm yr between the 1920s and 2000s. A reduction in the rate of subsidence through time was attributed to the transition from rapid initial consolidation and shrinkage to slower, long-term, ongoing oxidation. These subsidence rates agree well with a literature synthesis of temperate zone subsidence rates reported for similar lengths of time since drainage. A strong nonlinear relationship was found between temperate zone subsidence rates and time since initial peatland drainage: Subsidence (mm yr) = 226 × (years since drained) ( = 0.88). This relationship suggests that time since drainage exerts strong control over the rate of peatland subsidence and that ongoing peatland subsidence rates can be predicted to gradually decline with time in the absence of major land disturbance. PMID:25603091

  19. Vulnerability of the peatland carbon sink to sea-level rise.

    PubMed

    Whittle, Alex; Gallego-Sala, Angela V

    2016-01-01

    Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-level rise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr(-1) carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km(2) (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sea level, which are potentially vulnerable to inundation. PMID:27354088

  20. Vulnerability of the peatland carbon sink to sea-level rise

    PubMed Central

    Whittle, Alex; Gallego-Sala, Angela V.

    2016-01-01

    Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-level rise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr−1 carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km2 (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sea level, which are potentially vulnerable to inundation. PMID:27354088

  1. Late Holocene climate-induced forest transformation and peatland establishment in the central Appalachians

    NASA Astrophysics Data System (ADS)

    Booth, Robert K.; Ireland, Alex W.; LeBoeuf, Katharine; Hessl, Amy

    2016-03-01

    Understanding the potential for ecosystem transformation and community change in response to climate variability is central to anticipating future ecological changes, and long-term records provide a primary source of information on these dynamics. We investigated the late Holocene history of upland forest and peatland development at Cranesville Swamp, a peatland located along the West Virginia-Maryland border in the USA. Our primary goal was to determine whether establishment of peatland was triggered by moisture variability, similar to recent developmental models derived from depressional peatlands in glaciated regions. Results indicate that the peatland established at about 1200 cal yr BP, and was associated with a dramatic and persistent change in upland forest composition. Furthermore, timing of these upland and wetland ecological changes corresponded with evidence for multidecadal drought and enhanced moisture variability from nearby tree-ring and speleothem climatic reconstructions. Our results add to a growing body of research highlighting the sensitivity of both peatland development and upland forest communities to transient drought and enhanced moisture variability, and suggest that enhanced moisture variability in the future could increase the probability of similarly abrupt and persistent ecological change, even in humid regions like eastern North America.

  2. Distributed hydrological modeling with channel network flow of a forestry drained peatland site

    NASA Astrophysics Data System (ADS)

    Haahti, Kersti; Warsta, Lassi; Kokkonen, Teemu; Younis, Bassam A.; Koivusalo, Harri

    2016-01-01

    Peatland drainage has been an important component of forestry management in the boreal zone and the resulting ditch networks are maintained regularly to sustain forest productivity. In Finland, this is recognized as the most detrimental forestry practice increasing diffuse loads of suspended solids. Alongside forestry management on peatlands, interest in peatland restoration has grown lately. Distributed hydrological modeling has the potential to address these matters by recognizing relevant physical mechanisms and identifying most suitable strategies for mitigating undesired outcomes. This study investigates the utility of such a modeling approach in a drained peatland forest environment. To provide a suitable tool for this purpose, we coupled channel network flow to the three-dimensional distributed hydrological model FLUSH. The resulting model was applied to a 5.2 ha drained peatland forest catchment in Eastern Finland. The model was calibrated and validated using field measurements obtained over frost-free periods of five months. The application showed that distributed modeling can disentangle the importance of spatial factors on local soil moisture conditions, which is significant as peatland drainage aims to control these conditions. In our application, we limited the spatial aspect to the topography and the drainage network, and found that the drainage configuration had a clear effect on the spatial soil moisture patterns but that the effect was less pronounced during the wetter summer. Future applications of distributed modeling in this field comprises investigating the impacts of other spatial factors, modeling channel erosion and solid transport to address strategies for their mitigation, and evaluating restoration schemes.

  3. Effects of long-term drainage on microbial community composition vary between peatland types

    NASA Astrophysics Data System (ADS)

    Urbanová, Zuzana; Barta, Jiri

    2016-04-01

    Peatlands represent an important reservoir of carbon, but their functioning can be threatened by water level drawdown caused by climate or land use change. Knowledge of how microbial communities respond to long-term drainage in different peatland types could help improve predictions of the effect of climate change on these ecosystems. We investigated the effect of long-term drainage on microbial community composition in bog, fen and spruce swamp forests (SSF) in the Sumava Mountains (Czech Republic), using high-throughput barcoded sequencing, in relation to peat biochemical properties. Longterm drainage had substantial effects, which depended strongly on peatland type, on peat biochemical properties and microbial community composition. The effect of drainage was most apparent on fen, followed by SSF, and lowest on bog. Long-term drainage led to lower pH, reduced peat decomposability and increased bulk density, which was reflected by reduced microbial activity. Bacterial diversity decreased and Acidobacteria became the dominant phylum on drained sites, reflecting a convergence in bacterial community composition across peatlands after long-term drainage. The archaeal communities changed very strongly and became similar across drained peatlands. Overall, the characteristic differences between distinct peatland types under natural conditions were diminished by long-term drainage. Bog represented a relatively resilient system while fen seemed to be very sensitive to environmental changes.

  4. Vulnerability of the peatland carbon sink to sea-level rise

    NASA Astrophysics Data System (ADS)

    Whittle, Alex; Gallego-Sala, Angela V.

    2016-06-01

    Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-level rise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr‑1 carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km2 (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sea level, which are potentially vulnerable to inundation.

  5. Did fires drive Holocene carbon sequestration in boreal ombrotrophic peatlands of eastern Canada?

    NASA Astrophysics Data System (ADS)

    van Bellen, Simon; Garneau, Michelle; Ali, Adam A.; Bergeron, Yves

    2012-07-01

    Wildfire is an important factor on carbon sequestration in the North American boreal biomes. Being globally important stocks of organic carbon, peatlands may be less sensitive to burning in comparison with upland forests, especially wet unforested ombrotrophic ecosystems as found in northeastern Canada. We aimed to determine if peatland fires have driven carbon accumulation patterns during the Holocene. To cover spatial variability, six cores from three peatlands in the Eastmain region of Quebec were analyzed for stratigraphic charcoal accumulation. Results show that regional Holocene peatland fire frequency was ~ 2.4 fires 1000 yr- 1, showing a gradually declining trend since 4000 cal yr BP, although inter- and intra-peatland variability was very high. Charcoal peak magnitudes, however, were significantly higher between 1400 and 400 cal yr BP, possibly reflecting higher charcoal production driven by differential climatic forcing aspects. Carbon accumulation rates generally declined towards the late-Holocene with minimum values of ~ 10 g m- 2 yr- 1 around 1500 cal yr BP. The absence of a clear correlation between peatland fire regimes and carbon accumulation indicates that fire regimes have not been a driving factor on carbon sequestration at the millennial time scale.

  6. Water-table-dependent hydrological changes following peatland forestry drainage and restoration: Analysis of restoration success

    NASA Astrophysics Data System (ADS)

    Menberu, Meseret Walle; Tahvanainen, Teemu; Marttila, Hannu; Irannezhad, Masoud; Ronkanen, Anna-Kaisa; Penttinen, Jouni; Kløve, Bjørn

    2016-05-01

    A before-after-control approach was used to analyze the impact of peatland restoration on hydrology, based on high temporal resolution water-table (WT) data from 43 boreal peatlands representative of a south-boreal to north-boreal climate gradient. During the study, 24 forestry drained sites were restored and 19 pristine peatlands used as control sites. Different approaches were developed and used to analyze WT changes (mean WT position, WT fluctuation, WT hydrograph, recession, and storage characteristics). Restoration increased WT in most cases but particularly in spruce mires, followed by pine mires and fens. Before restoration, the WT fluctuation (WTF) was large, indicating peat temporary storage gain (SG). After restoration, the WT hydrograph recession limb slopes and SG coefficients (Rc) declined significantly. Drainage or restoration did not significantly affect mean diurnal WT fluctuations, used here as a proxy for evapotranspiration. Overall, the changes in WT characteristics following restoration indicated creation of favorable hydrological conditions for recovery of functional peatland ecosystems in previously degraded peatland sites. This was supported by calculation of bryophyte species abundance thresholds for WT. These results can be used to optimize restoration efforts in different peatland systems and as a qualitative conceptual basis for future restoration operations.

  7. Peatland restoration and effects on groundwater, water quality and runoff

    NASA Astrophysics Data System (ADS)

    Menberu, Meseret; Tahvanainen, Teemu; Irannezhad, Masoud; Ronkanen, Anna-Kaisa; Marttila, Hannu; Penttinen, Jouni; Klöve, Björn

    2015-04-01

    There is increasing interest to restore degraded peatland, but long term effects of restoration are poorly known. Totally 46 boreal peatland were included in a study set, including 20 fens, 13 pine mires and 13 spruce mires, with peatland types ranging from nearly ombrotrophic Sphagnum bogs to rich fens. Study sites covered spatially almost whole Finland. Furthermore, 27 of the sites were previously drained and restored during the monitoring period, while the remaining 19 sites were in pristine condition. The pristine sites were held as paired counterparts of the drained sites and are located in the vicinity of drained/restored sites to ensure similar vegetation, nutrient and hydrological status. Since 2008, water table fluctuation (continuous measurement), pore water chemistry at all sites, and runoff and water chemistry (nutrients, DOC, ions with adjusted intervals through frost-free season) from 9 sites were studied. Drained/restored sites were monitored for 1 to 3 years before restoration. This presentation shows preliminary results and analysis of present dataset. Restoration operation increased water table (WT) in all study areas, but high variation was observed. Highest change in WT elevation was observed in spruce mires and smaller increases in fens. Disturbance of peat material and higher WT caused leaching of nutrients and ions from restoration areas, e.g. phosphorus, nitrogen and iron. Increase was highest during the first year after restoration, but showed decreasing trend almost in all study areas in pore-water samples. Generally it can be concluded that restoration have reached its main target for elevated WT, launching re-development of acrotelm peat layers. However, restoration operation caused disturbance and elevated nutrient loading to water courses. Preliminary results of statistical analysis revealed no significant differences of mean daily runoff between drained and pristine counterparts. After restoration, one study site showed decrease in

  8. Comparisons of soil nitrogen mass balances for an ombrotrophic bog and a minerotrophic fen in northern Minnesota.

    PubMed

    Hill, Brian H; Jicha, Terri M; Lehto, LaRae L P; Elonen, Colleen M; Sebestyen, Stephen D; Kolka, Randall K

    2016-04-15

    We compared nitrogen (N) storage and flux in soils from an ombrotrophic bog with that of a minerotrophic fen to quantify the differences in N cycling between these two peatlands types in northern Minnesota (USA). Precipitation, atmospheric deposition, and bog and fen outflows were analyzed for nitrogen species. Upland and peatland soil samples were analyzed for N content, and for ambient (DN) and potential (DEA) denitrification rates. Annual atmospheric deposition was: 0.88-3.07kg NH4(+)ha(-1)y(-1); 1.37-1.42kg NO3(-)ha(-1)y(-1); 2.79-4.69kg TNha(-1)y(-1). Annual N outflows were: bog-0.01-0.04kg NH4(+)ha(-1)y(-1), NO3(-) 0.01-0.06kgha(-1)y(-1), and TN 0.11-0.69kgha(-1)y(-1); fen-NH4(+) 0.01-0.16kgha(-1)y(-1), NO3(-) 0.29-0.48kgha(-1)y(-1), and TN 1.14-1.61kgha(-1)y(-1). Soil N content depended on location within the bog or fen, and on soil depth. DN and DEA rates were low throughout the uplands and peatlands, and were correlated with atmospheric N deposition, soil N storage, and N outflow. DEA was significantly greater than DN indicating C or N limitation of the denitrification process. We highlight differences between the bog and fen, between the upland mineral soils and peat, and the importance of biogeochemical hotspots within the peatlands. We point out the importance of organic N storage, as a source of N for denitrification, and propose a plausible link between organic N storage, denitrification and N export from peatlands. Finally, we considered the interactions of microbial metabolism with nutrient availability and stoichiometry, and how N dynamics might be affected by climate change in peatland ecosystems. PMID:26851760

  9. Resilience of Arctic Permafrost Carbon in Mackenzie River Basin: An Incubation Experiment to Observe Priming Potentials and Biodegradability of Arctic Permafrost Peatlands

    NASA Astrophysics Data System (ADS)

    Hedgpeth, A.; Beilman, D.; Crow, S. E.

    2015-12-01

    Arctic permafrost zones cover 25% of the Northern Hemisphere and hold 1672Pg of soil carbon (C) with 277Pg in Arctic permafrost peatlands, which is 1/3 of the CO2 in the atmosphere. This currently protected C is a potential source for increased emissions in a warmer climate. Longer growing seasons resulting in increased plant productivity above and below ground may create new labile C inputs with the potential to affect mineralization of previously stable SOM, known as the priming effect. This study examined the response of soil respiration to labile substrate addition in carbon-rich (42-48 %C) permafrost peatland soils along a N-S transect in the central Mackenzie River Basin (69.2-62.6°N). Active layer and near surface soils (surface Δ14C values > -140.0) were collected from four sites between -10.5 and -5.2 MAT. Soils were spiked with 0.5 mg D-glucose g-1soil, and incubated at 10°C for 23 days to determine potential, short term (i.e., apparent) priming effects. On average glucose addition increased respiration in all samples. One site showed priming evidence in active layer soils despite one-way ANOVA not illustrating statistically significant differences between control and treated final cumulative CO2. Apparent priming effects were seen in two near surface permafrost samples, however cumulative increases in CO2 were not identified as significant. When all results from all sites and depths were considered, the addition of glucose showed no significant effect on total CO2 production relative to controls (p=0.957), suggesting that these sites may be resilient to increased inputs in that little priming evidence was observed. To test the idea that the soils that showed priming effects are of poorer quality, we conducted an additional incubation experiment to explore the biodegradability of these permafrost peatland soils. Soils from these four sites were inoculated and incubated for 17 days. The two sites with observed priming showed the highest biodegradability

  10. Effects of experimental warming and elevated CO2 on surface methane and CO­2 fluxes from a boreal black spruce peatland

    NASA Astrophysics Data System (ADS)

    Gill, A. L.; Finzi, A.; Giasson, M. A.

    2015-12-01

    High latitude peatlands represent a major terrestrial carbon store sensitive to climate change, as well as a globally significant methane source. While elevated atmospheric carbon dioxide concentrations and warming temperatures may increase peat respiration and C losses to the atmosphere, reductions in peatland water tables associated with increased growing season evapotranspiration may alter the nature of trace gas emission and increase peat C losses as CO2 relative to methane (CH4). As CH4 is a greenhouse gas with twenty times the warming potential of CO2, it is critical to understand how surface fluxes of CO2 and CH4 will be influenced by factors associated with global climate change. We used automated soil respiration chambers to assess the influence of elevated atmospheric CO2 and whole ecosystem warming on peatland CH4 and CO2 fluxes at the SPRUCE (Spruce and Peatland Responses Under Climatic and Environmental Change) Experiment in northern Minnesota. Belowground warming treatments were initiated in July 2014 and whole ecosystem warming and elevated CO2 treatments began in August 2015. Here we report soil iCO2 and iCH4 flux responses to the first year of belowground warming and the first two months of whole ecosystem manipulation. We also leverage the spatial and temporal density of measurements across the twenty autochambers to assess how physical (i.e., plant species composition, microtopography) and environmental (i.e., peat temperature, water table position, oxygen availability) factors influence observed rates of CH4 and CO2 loss. We find that methane fluxes increased significantly across warming treatments following the first year of belowground warming, while belowground warming alone had little influence on soil CO2 fluxes. Peat microtopography strongly influenced trace gas emission rates, with higher CH4 fluxes in hollow locations and higher CO2 fluxes in hummock locations. While there was no difference in the isotopic composition of the methane

  11. The impact of sheep grazing on the carbon balance of a peatland.

    PubMed

    Worrall, Fred; Clay, Gareth D

    2012-11-01

    Estimates of the greenhouse gas (GHG) fluxes resulting from sheep grazing upon upland peat soils have never been fully quantified. Previous studies have been limited to individual flux pathways or to comparing the presence to the absence of sheep grazing. Therefore, this study combines a model of the physical impact of grazing with models of: biomass production; energy usage in sheep; and peat accumulation. These combined modelling approaches enabled this study to consider the indirect and direct impacts of sheep upon the carbon and greenhouse gas balance of a peatland at different grazing intensities as well as the changes between grazing intensities. The study considered four vegetation scenarios (Calluna sp., Molinia sp.; reseeded grasses, and Agrostis-Festuca grassland) and a mixed vegetation scenario based upon the vegetation typical of upland peat ecosystems in northern England. Each scenario was considered for altitudes between 350 and 900 m above sea level and for grazing intensities between 0.1 and 2 ewes/ha. The study can show that the total GHG flux at the vegetative carrying capacity tended to decline with increasing altitude for all vegetation scenarios considered except for Molinia sp. The average total GHG flux for all scenarios was 1505 kg CO(2)eq/ha/yr/(ewe/ha), and on average 89% of the fluxes were directly from the sheep and not from the soil, and are therefore not unique to a peat soil environment. The study suggests that emission factors for upland sheep have been greatly underestimated. By comparing the total flux due to grazers to the flux to or from the soil that allows the study to define a GHG carry capacity, i.e. the grazing intensity at which the flux due to grazing is equal to the sink represented by the peat soils, this GHG carrying capacity varies between 0.2 and 1.7 ewes/ha with this capacity declining with increasing altitude for all model scenarios. PMID:23026149

  12. Variable source and age of different forms of carbon released from natural peatland pipes

    NASA Astrophysics Data System (ADS)

    Billett, M. F.; Dinsmore, K. J.; Smart, R. P.; Garnett, M. H.; Holden, J.; Chapman, P.; Baird, A. J.; Grayson, R.; Stott, A. W.

    2012-06-01

    We used the carbon isotope composition (14C and δ13C) to measure the source and age of DOC, POC, dissolved CO2 and CH4 (δ13C only) released from three natural peat pipes and the downstream catchment outlet of a small peatland in northern England. Sampling under different hydrological extremes (high flows associated with storm events and low flows before or after storms) was used to explore variability in C sources as flow paths change over short periods of time. The δ13C composition of organic C differed (δ13C-DOC -28.6‰ to -27.6‰;δ13C-POC -28.1‰ to -26.1‰) from that of the dissolved gases (δ13C-CO2 -20.5‰ to +1.1‰; δ13C-CH4-67.7‰ to -42.0‰) and showed that C leaving the catchment was a mixture of shallow/deep pipe and non-pipe sources. The isotopic composition of the dissolved gases was more variable than DOC and POC, with individual pipes either showing13C enrichment or depletion during a storm event. The 14C age of DOC was consistently modern at all sites; POC varied from modern to 653 years BP and evasion CO2 from modern to 996 years BP. Differences in the isotopic composition of evasion CO2 at pipe outlets do not explain the variability in δ13C and 14C at the catchment outlet and suggest that overland flow is likely to be an important source of CO2. Our results also show that the sources of CO2 and CH4 are significantly more variable and dynamic than DOC and POC and that natural pipes vent old, deep peat CO2 and POC (but not DOC) to the atmosphere.

  13. Fire and Long-Term Carbon Accumulation in Boreal Peatlands are Controlled by Interactions Between Climate and Successional Dynamics

    NASA Astrophysics Data System (ADS)

    Camill, P.; Rafert, G.; Barry, A.; Williams, E.; Andreassi, C.; Limmer, J.; Solick, D.

    2008-12-01

    Warming climate has the potential to dramatically alter carbon and fire dynamics in high-latitude systems. Boreal and subarctic peatlands cover 346 million hectares of land surface and store 455 Pg-C, suggesting that changes in these systems can have regional and global-scale impacts on carbon cycling. Soil carbon release is expected to increase with more frequent fires in a warmer world. The dynamics of peatland landscapes, however, will likely involve complex interactions among permafrost thaw, changes in hydrology, and successional development. Understanding landscape-level responses to warming therefore requires integrative approaches that simultaneously examine all of these processes. In this study, we examined long- term changes in plant succession, carbon accumulation, and fire in a landscape located in northern Manitoba, Canada. We recovered 17 replicate permafrost peat cores ranging in depth from 1-4.3 meters (mean = 2.2 m). Using 149 AMS 14C dates, we were able to develop detailed age chronologies for each core. We measured macrofossil abundance to reconstruct the wetland plant community, areal charcoal concentration (mm2cm-3) as a proxy for fire severity, and total carbon and nitrogen. Basal AMS 14C dates indicated that peat accumulation began almost synchronously around 8,000 cal.14C yr BP, with the exception of a few cores resulting from more recent paludification along the wetland margin. Fire severity increased across wetland successional stages, with later successional forested bogs showing greater severity (6.79-11.16 mm2cm-3) than early successional open water, fen, and poor fen communities (0.29-1.82 mm2cm-3). The exception was paludified lowland forests, which exhibited the greatest fire severity during peatland initiation and the death of the overstory (21.68 mm2cm- 3). More severe fires (> 5-10 mm2cm-3) caused peat carbon accumulation rates to decline by half (13.7-24.5 g-Cm-2yr-1) compared to unburned peat (48.9 g-Cm-2yr-1). These two results

  14. The compost bomb: thermal instability in peatland soils

    NASA Astrophysics Data System (ADS)

    Luke, C. M.; Cox, P. M.

    2009-04-01

    A simple model is constructed to investigate the effect of thermal energy generated by microbial respiration on soil temperature and soil carbon stocks, specifically in peat soils. Stability analysis shows a potential tipping point in the system beyond which a sudden large increase in soil temperature and decrease in soil carbon is predicted. Stability of the system depends on a dimensionless number, itself dependent on the effective soil thermal conductivity and the temperature sensitivity of microbial respiration. The influence of soil moisture on the effective thermal conductivity, and therefore the stability of the system, is also investigated. These results suggest that peatland soils insulated by a moss or lichen layer are potentially destabilised under certain conditions of warming and drying.

  15. Ammonium release from a blanket peatland into headwater stream systems.

    PubMed

    Daniels, S M; Evans, M G; Agnew, C T; Allott, T E H

    2012-04-01

    Hydrochemical sampling of South Pennine (UK) headwater streams draining eroded upland peatlands demonstrates these systems are nitrogen saturated, with significant leaching of dissolved inorganic nitrogen (DIN), particularly ammonium, during both stormflow and baseflow conditions. DIN leaching at sub-catchment scale is controlled by geomorphological context; in catchments with low gully densities ammonium leaching dominates whereas highly gullied catchments leach ammonium and nitrate since lower water tables and increased aeration encourages nitrification. Stormflow flux calculations indicate that: approximately equivalent amounts of nitrate are deposited and exported; ammonium export significantly exceeds atmospheric inputs. This suggests two ammonium sources: high atmospheric loadings; and mineralisation of organic nitrogen stored in peat. Downstream trends indicate rapid transformation of leached ammonium into nitrate. It is important that low-order headwater streams are adequately considered when assessing impacts of atmospheric loads on the hydrochemistry of stream networks, especially with respect to erosion, climate change and reduced precipitation. PMID:22285801

  16. Monitoring Peatland ecosystem dynamics using multisensor satellite data

    NASA Astrophysics Data System (ADS)

    Romshoo, S.; Shimada, M.; Igarashi, T.; Rosenqvist, A.

    Peatlands are multi-functional natural systems, which perform many globally, regionally, and locally important natural resource functions. They are key links in the cycles of water, carbon and other chemical elements and substances, supporting biological diversity, and accumulating energy, matter and information. Their total carbon pool exceeds that of the world's forests and equals that of the atmosphere. They are complex systems with a specific environm nt in which they exist ande function. The range and importance of the diverse functions, services and resources provided by peatlands are changing with increases in human demand and development of new technologies. These functions can have different values on different spatial (local, regional, national, international, etc.) and temporal (short- term and long-term) levels that may lead to intersectoral conflicts and problems for co-ordinating wise management of peatlands. Keeping in view their ecological and economic importance in the Southeast Asian region, an integrated study was conducted, employing JERS-1 SAR and optical data, to find out how the SAR data could be used to understand the complex ecological processes of these ecosystems. As a first step, it was found out that large tracts of these peatlands have been lost as a result of being diverted to other unproductive land uses from 1994 to 1998 and the process is going on unabated. Such a reckless destruction of these carbon rich forests have resulted in the release of huge amount of carbon to the atmosphere as confirmed from the flux measurements in the area. In order to better understand and quantify the cycles of carbon and water in these ecosystem using bio-geophysical models, it is important to characterize the vegetation and seasonal patterns of the inundation. Both, a single scene and a time series of L-band SAR data were used for the land surface characterization. The vegetation characterization was markedly improved with the use of a time series

  17. Methane emission modeling with MCMC calibration for a boreal peatland

    NASA Astrophysics Data System (ADS)

    Raivonen, Maarit; Smolander, Sampo; Susiluoto, Jouni; Backman, Leif; Li, Xuefei; Markkanen, Tiina; Kleinen, Thomas; Makela, Jarmo; Aalto, Tuula; Rinne, Janne; Brovkin, Victor; Vesala, Timo

    2016-04-01

    Natural wetlands, particularly peatlands of the boreal latitudes, are a significant source of methane (CH4). At the moment, the emission estimates are highly uncertain. These natural emissions respond to climatic variability, so it is necessary to understand their dynamics, in order to be able to predict how they affect the greenhouse gas balance in the future. We have developed a model of CH4 production, oxidation and transport in boreal peatlands. It simulates production of CH4 as a proportion of anaerobic peat respiration, transport of CH4 and oxygen between the soil and the atmosphere via diffusion in aerenchymatous plants and in peat pores (water and air filled), ebullition and oxidation of CH4 by methanotrophic microbes. Ultimately, we aim to add the model functionality to global climate models such as the JSBACH (Reick et al., 2013), the land surface scheme of the MPI Earth System Model. We tested the model with measured methane fluxes (using eddy covariance technique) from the Siikaneva site, an oligotrophic boreal fen in southern Finland (61°49' N, 24°11' E), over years 2005-2011. To give the model estimates regional reliability, we calibrated the model using Markov chain Monte Carlo (MCMC) technique. Although the simulations and the research are still ongoing, preliminary results from the MCMC calibration can be described as very promising considering that the model is still at relatively early stage. We will present the model and its dynamics as well as results from the MCMC calibration and the comparison with Siikaneva flux data.

  18. Variable carbon losses from recurrent fires in drained tropical peatlands.

    PubMed

    Konecny, Kristina; Ballhorn, Uwe; Navratil, Peter; Jubanski, Juilson; Page, Susan E; Tansey, Kevin; Hooijer, Aljosja; Vernimmen, Ronald; Siegert, Florian

    2016-04-01

    Tropical peatland fires play a significant role in the context of global warming through emissions of substantial amounts of greenhouse gases. However, the state of knowledge on carbon loss from these fires is still poorly developed with few studies reporting the associated mass of peat consumed. Furthermore, spatial and temporal variations in burn depth have not been previously quantified. This study presents the first spatially explicit investigation of fire-driven tropical peat loss and its variability. An extensive airborne Light Detection and Ranging data set was used to develop a prefire peat surface modelling methodology, enabling the spatially differentiated quantification of burned area depth over the entire burned area. We observe a strong interdependence between burned area depth, fire frequency and distance to drainage canals. For the first time, we show that relative burned area depth decreases over the first four fire events and is constant thereafter. Based on our results, we revise existing peat and carbon loss estimates for recurrent fires in drained tropical peatlands. We suggest values for the dry mass of peat fuel consumed that are 206 t ha(-1) for initial fires, reducing to 115 t ha(-1) for second, 69 t ha(-1) for third and 23 t ha(-1) for successive fires, which are 58-7% of the current IPCC Tier 1 default value for all fires. In our study area, this results in carbon losses of 114, 64, 38 and 13 t C ha(-1) for first to fourth fires, respectively. Furthermore, we show that with increasing proximity to drainage canals both burned area depth and the probability of recurrent fires increase and present equations explaining burned area depth as a function of distance to drainage canal. This improved knowledge enables a more accurate approach to emissions accounting and will support IPCC Tier 2 reporting of fire emissions. PMID:26661597

  19. The Carbon Stocks of Peatlands Under Forestry in the Republic of Ireland.

    NASA Astrophysics Data System (ADS)

    Wellock, M.; Laperle, C.; Kiely, G.; Reidy, B.; Duffy, C.; Tobin, B.

    2009-04-01

    Under the Kyoto Protocol it is necessary for all industries (including forestry) within the Republic of Ireland to report their GHG emission sinks and sources. Forestry plays an important role within the global carbon cycle as a carbon store within the biomass (above- and below-ground), litter and soil. Along with forests, peatlands are another important store for carbon, holding around one third of the global soil carbon pool. Peatlands held very important roles for irish society for hundreds of years, i.e. agriculture, horticulture, energy etc, and cover approximately 17.2 % or 1.34 million ha of the total irish land area (Hammond, 1981) with around 260,000 ha of the peatland forested (NFI, 2007). Afforestation of peatlands began in Ireland in the 1950s with the majority of the planting being done by the state. At present the state doesn't forest peatland, but there is still substantial planting from the private sector. Afforested peatland in Ireland represents a large store of C and so far there has been no quantification of the total carbon stock of the soil. The project FORESTC is aiming to provide an analysis of the stocks of C that are stored within the afforested peatlands of Ireland. To achieve this 20 forested peatland sites around Ireland will be sampled, comprising 5 conifer, low level blanket peat sites (peats located at elevations lower than 150 m), 5 conifer, high level blanket peat sites (peats located at elevations greater than 150 m), 5 conifer basin peats and 5 mixed conifer and broadleaf basin peats. The peat will be sampled down the entire soil profile up to 10 m deep for both bulk density and carbon % every 50 cm using a peat sampler (Eijlelkamp, NL). Along with the peat samples, litter and F/H layer samples will be taken to quantify the carbon stock of the litter layer atop the peat. This data shall then be able to provide a total carbon stock of these 20 forest sites that hopefully will allow for the estimation of the total C stock of the

  20. Stable isotopes of water in estimation of groundwater dependence in peatlands

    NASA Astrophysics Data System (ADS)

    Isokangas, Elina; Rossi, Pekka; Ronkanen, Anna-Kaisa; Marttila, Hannu; Rozanski, Kazimierz; Kløve, Bjørn

    2016-04-01

    Peatland hydrology and ecology can be irreversibly affected by anthropogenic actions or climate change. Especially sensitive are groundwater dependent areas which are difficult to determine. Environmental tracers such as stable isotopes of water are efficient tools to identify these dependent areas and study water flow patterns in peatlands. In this study the groundwater dependence of a Finnish peatland complex situated next to an esker aquifer was studied. Groundwater seepage areas in the peatland were localized by thermal imaging and the subsoil structure was determined using ground penetrating radar. Water samples were collected for stable isotopes of water (δ18O and δ2H), temperature, pH and electrical conductivity at 133 locations of the studied peatland (depth of 10 cm) at approximately 100 m intervals during 4 August - 11 August 2014. In addition, 10 vertical profiles were sampled (10, 30, 60 and 90 cm depth) for the same parameters and for hydraulic conductivity. The cavity ring-down spectroscopy (CRDS) was applied to measure δ18O and δ2H values. The local meteoric water line was determined using precipitation samples from Nuoritta station located 17 km west of the study area and the local evaporation line was defined using water samples from lake Sarvilampi situated on the studied peatland complex. Both near-surface spatial survey and depth profiles of peatland water revealed very wide range in stable isotope composition, from approximately -13.0 to -6.0 ‰ for δ18O and from -94 to -49 ‰ for δ2H, pointing to spatially varying influence of groundwater input from near-by esker aquifer. In addition, position of the data points with respect to the local meteoric water line showed spatially varying degree of evaporation of peatland water. Stable isotope signatures of peatland water in combination with thermal images delineated the specific groundwater dependent areas. By combining the information gained from different types of observations, the

  1. Magnitude and Significance of Carbon Burial in Lakes, Reservoirs, and Northern Peatlands

    USGS Publications Warehouse

    U.S. Geological Survey

    1999-01-01

    It is estimated that freshwater lakes in the world have a total area of about 1.5x1012 m2 (Shiklomanov, 1993; table 1). Including saline inland seas in this total would add another 1x1012 m2. The 28 largest (area of each > 5,000 km2) freshwater lakes in the world have a total area of 1.18x1012 m2 or about 79 percent of the total area of all freshwater lakes. If the 28 large lakes bury organic carbon (OC), on average, at the same rate as Lake Michigan (5 g/m2/yr), then the annual rate of OC burial in these 28 lakes is about 6 Tg/yr (6 terragrams per year or 6x1012 g/yr; table 1). If the smaller lakes bury OC, on average, at the same rate as an average Minnesota lake (72 g/m2/yr), then the annual rate of OC accumulation in these smaller lakes is about 23 Tg/yr (23x1012 g/yr; table 1). If saline inland seas bury OC at the Lake Michigan rate, this would be an additional 5 Tg/yr, for a total of 34 Tg/yr for all freshwater lakes and saline inland seas (table 1). Mulholland and Elwood (1982) estimated the OC burial in all lakes and inland seas (excluding the Black Sea) to be 60 Tg/yr today (table 1) and an average of 20 Tg/yr for the last 10,000 years. Stallard (1998) modeled terrestrial sedimentation as a series of 864 scenarios. For lake area, he used 1.54x1012 m2, the area of the 250 largest lakes in the world. This is close to the total of large and small lakes given in table 1. Again, including inland seas to this total would add an additional 1x1012 m2. Results of scenarios for lakes and reservoirs were divided into two components, those with clastic sediments and those with organic sediments. The results of OC burial in the most likely of Stallard's scenarios for lakes range from 48 to 72 Tg/yr (table 1), the average of which is close to the 60 Tg/yr estimated by Mulholland and Elwood (1982). We will use an average of 54 Tg/yr (table 1). The closeness of these estimates, calculated by different methods, suggests that this value is not in error by more than a factor of two.

  2. Evaluating CO2 and CH4 fluxes in Arctic peatland and tundra using a satellite remote sensing driven biophysical model

    NASA Astrophysics Data System (ADS)

    Watts, J.; Kimball, J. S.; Parmentier, F. W.; Sachs, T.; Rinne, J.; Zona, D.; Oechel, W. C.; Tagesson, T.

    2013-12-01

    The Arctic terrestrial carbon sink is contingent on the balance between vegetation gross primary productivity (GPP) and emissions of carbon dioxide (CO2) and methane (CH4). With climate change, warming temperatures could increase GPP within high latitude systems but may also accelerate soil decomposition and CO2 loss. Regional wetting may also shift carbon emissions towards greater CH4 release, a greenhouse gas at least 25 times more potent than CO2. However, an effective framework for monitoring changes in the Arctic net ecosystem carbon balance (NECB) is lacking. Here we introduce an integrated terrestrial carbon flux (TCF) model approach to estimate CO2 and CH4 fluxes from northern peatland and tundra ecosystems at a daily time step. The TCF model framework uses a light-use efficiency (LUE) algorithm to estimate GPP according to satellite NDVI inputs and estimated moisture and temperature constraints. Ecosystem respiration is derived using a three-pool soil organic carbon decomposition model regulated by surface (< 10 cm depth) soil temperature and volumetric moisture inputs. A TCF-CH4 component simulates gas production according to near-surface temperature, anaerobic soil fractions and labile soil carbon inputs derived during model spin-up. Plant transport, soil diffusion and ebullition pathways are used to regulate CH4 emissions into the atmosphere. The combined TCF CO2 and CH4 model was evaluated against tower eddy covariance (EC) flux datasets from six peatland and tundra sites in North America, Eurasia and Greenland. TCF model simulations driven with site information explained on average > 70% (r^2; p < 0.05) of the respective EC record 8-day cumulative CO2 and CH4 fluxes. The TCF results from model simulations using coarser satellite (MODIS 250-m resolution) and reanalysis (MERRA; 1/2 x 2/3° resolution) inputs were more variable, but captured the overall seasonality and magnitude of ecosystem carbon exchange. Model simulations of annual carbon fluxes

  3. Tracing peatland geomorphology: sediment and contaminant movements in eroding and restored systems

    NASA Astrophysics Data System (ADS)

    Shuttleworth, Emma; Evans, Martin; Hutchinson, Simon; Rothwell, James

    2015-04-01

    Peatlands are an important store of soil carbon, play a vital role in global carbon cycling, and can also act as sinks of atmospherically deposited heavy metals. However, large areas of blanket peat are significantly degraded and actively eroding as a direct result of anthropogenic pressures, which negatively impacts carbon and pollutant storage. The restoration of eroding UK peatlands is a major conservation concern, and over the last decade measures have been taken to control erosion and restore large areas of degraded peat. In severely eroded peatlands, topography is highly variable, and an appreciation of geomorphological form and process is key in understanding the controls on peatland function, and in mitigating the negative impacts of peatland erosion. The blanket peats of the Peak District, Southern Pennines, UK embody many problems and pressures faced by peatlands globally, and are amongst the most heavily eroded and contaminated in the world. The near-surface layer of the peat is contaminated by high concentrations of anthropogenically derived, atmospherically deposited heavy metals which are released into the fluvial system as a consequence of widespread erosion. Whilst not desirable, this legacy of lead pollution and its release offer a unique opportunity to trace peatland sediment movements and thus investigate the controls on sediment and contaminant mobility. A suite of established field, analytical and modelling techniques have been modified and adapted for use in peatland environments and these have been successfully employed in combination to address issues of sediment and contaminant release at a range of scales, including: (i) the development of field portable XRF to assess in situ lead concentrations in wet organic sediments; (ii) adaptation of time integrated mass flux samplers to explore spatial and temporal sediment dynamics in peatland streams; and (iii) the application of sediment source fingerprinting and numerical mixing models to

  4. Importance of West Siberian Peatlands to Global Carbon and Water Cycles

    NASA Astrophysics Data System (ADS)

    Smith, L. C.

    2014-12-01

    Russia's West Siberian Lowland (WSL) contains nearly 600,000 km2 of peatlands with depth >0.5 m, the most extensive such deposits in the world. These peatlands impact the global carbon cycle, representing an important CH4 source and net CO2 sink since the early Holocene. However, together with other Arctic and sub-Arctic peatlands, the likely responses of WSL peatlands to warming climate and associated permafrost degradation are a subject of ongoing study and debate. Of prime interest is whether WSL peatlands may switch from a net carbon sink to source, especially in permafrost peatlands. Climate models predict warmer temperatures, longer growing seasons, and enhanced precipitation which should increase net primary productivity and litter production, but also soil microbial decomposition, increasing release of sequestered carbon through outgassing of CH4 and/or CO2 to the atmosphere. Projecting the net outcome of these opposing ecosystem processes on carbon sink/source status requires is difficult, and given strong N-S temperature and permafrost gradients across the WSL, the response will likely vary geographically. Hydrological status is deeply important because aerobic dry peats emit a greater fraction of CO2 whereas anaerobic wet peats predominately release CH4. A first estimate of subsurface water storage in WSL peatlands suggests they may hold ~1,200 km3 of liquid-water equivalent (~2 m), a large number that is roughly triple the annual flow of water in the Ob' River. New models, observations, and synthesis are needed to confidently project the future role of this important region to global carbon and water cycles.

  5. Contrasting vulnerability of drained tropical and high-latitude peatlands to fluvial loss of stored carbon

    NASA Astrophysics Data System (ADS)

    Evans, Chris D.; Page, Susan E.; Jones, Tim; Moore, Sam; Gauci, Vincent; Laiho, Raija; Hruška, Jakub; Allott, Tim E. H.; Billett, Michael F.; Tipping, Ed; Freeman, Chris; Garnett, Mark H.

    2014-11-01

    Carbon sequestration and storage in peatlands rely on consistently high water tables. Anthropogenic pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of peat-forming vegetation and exposure of previously anaerobic peat to aerobic decomposition. This can shift peatlands from net CO2 sinks to large CO2 sources, releasing carbon held for millennia. Peatlands also export significant quantities of carbon via fluvial pathways, mainly as dissolved organic carbon (DOC). We analyzed radiocarbon (14C) levels of DOC in drainage water from multiple peatlands in Europe and Southeast Asia, to infer differences in the age of carbon lost from intact and drained systems. In most cases, drainage led to increased release of older carbon from the peat profile but with marked differences related to peat type. Very low DOC-14C levels in runoff from drained tropical peatlands indicate loss of very old (centuries to millennia) stored peat carbon. High-latitude peatlands appear more resilient to drainage; 14C measurements from UK blanket bogs suggest that exported DOC remains young (<50 years) despite drainage. Boreal and temperate fens and raised bogs in Finland and the Czech Republic showed intermediate sensitivity. We attribute observed differences to physical and climatic differences between peatlands, in particular, hydraulic conductivity and temperature, as well as the extent of disturbance associated with drainage, notably land use changes in the tropics. Data from the UK Peak District, an area where air pollution and intensive land management have triggered Sphagnum loss and peat erosion, suggest that additional anthropogenic pressures may trigger fluvial loss of much older (>500 year) carbon in high-latitude systems. Rewetting at least partially offsets drainage effects on DOC age.

  6. Carbon stored in peatlands formed by terrestrialization: the importance of buried lake sediments

    NASA Astrophysics Data System (ADS)

    Talbot, J.

    2015-12-01

    A lot of efforts have been made over the last few decades to quantify the amount of carbon stored in soils, including in peat-producing systems. Estimates of soil carbon storage at the landscape scale has to take into account all buried carbon pools, including deep-buried lake sediments found under many peatlands that formed by terrestrialization. To illustrate the importance of buried lake sediments in the overall carbon storage of a peatland site, we studied a small peat swamp located in Gatineau Park (Quebec, Canada), the Folly peatland (45°27'18.12"N 75°46'57.38''W). This 7 ha peatland developed from a small lake that appeared after the postglacial Champlain Sea receded from the region, about 12 200 years ago. Its development followed a classical terrestrialization sequence and its hydrology has been stable since peat inception. A profile of over 8.5 m of organic matter was collected at the site, of which 2.5 m is peat and the rest is composed of lake sediments (gyttja). With the exception of a few tephra layers, the organic matter content exceeds 75 % of dry weight for the entire profile. Although it constitutes only 30 % of the profile depth, peat contains 48 % of the buried carbon because of its higher bulk density, and peat carbon accumulated at a rate of 88 g C m-2 yr-1. Overall, the site carbon density (including buried lake sediments) is 172 kg C m-2, a value comparable to the carbon density of many peatlands with much deeper peat profiles. The implications of these findings are discussed in the context of global peatland carbon inventories and peatland biogeochemistry.

  7. Burned and unburned peat water repellency: Implications for peatland evaporation following wildfire

    NASA Astrophysics Data System (ADS)

    Kettridge, N.; Humphrey, R. E.; Smith, J. E.; Lukenbach, M. C.; Devito, K. J.; Petrone, R. M.; Waddington, J. M.

    2014-05-01

    Water repellency alters soil hydrology after periods of wildfire, potentially modifying the ecosystem recovery to such disturbance. Despite this potential importance, the extent and severity of water repellency within burned peatlands and its importance in regulating peatland recovery to wildfire disturbance remains poorly understood. We characterised the water repellency of peat in a burned (one year post-fire) and unburned peatland in the Western Boreal Plain utilising the water drop penetration time and ethanol droplet molarity tests. Burned Sphagnum moss and feather moss sites had a more severe degree of water repellency than unburned sites, with differences being more pronounced between burned and unburned feather moss sites. Burned feather moss exhibited the most extreme water repellency, followed by unburned feather moss, and burned Sphagnum. The severity of water repellency varied with depth through the near surface of the moss/peat profile. This was most evident within the burned feathermoss where more extreme water repellency was observed at the near-surface compared to the surface, with the most extreme water repellency found at 1 and 5 cm depths. Unburned Sphagnum was completely hydrophilic at all depths. We suggest that the extreme water repellency in near-surface feather moss peat acts as a barrier that impedes the supply of water to the surface that replaces that lost via evaporation. This leads to drying of the near-surface vadose zone within feather moss areas and a concomitantly large decrease in peatland evaporation within feather moss dominated peatlands. This negative feedback mechanism likely enhances the resilience of such peatland to wildfire disturbance, maintaining a high water table position, thereby limiting peat decomposition. In comparison, such a feedback is not observed strongly within Sphagnum, leaving Sphagnum dominated peatlands potentially vulnerable to low water table positions post disturbance.

  8. Measurement and modelling of the sources and sinks of greenhouse gases from northern wetlands

    NASA Astrophysics Data System (ADS)

    Roulet, N. T.; Frolking, S.; Lafleur, P. M.; Moore, T. R.; Richard, P. H. J.

    2003-04-01

    Northern wetlands contain ≈30% of the world's terrestrial carbon store, resulting from the incomplete decomposition of plant material inhibited because oxygen diffusion is limited by water saturation of the soil. While this behaviour results in a sink for CO_2, anaerobic pathways of decomposition result in wetlands being a large, but variable, source of CH_4. Northern wetlands tend to be nitrogen-impoverished, therefore they are not an important source of N_2O. However, nitrogen deposition, peat extraction, and other land-use changes have the potential to alter their greenhouse gas (GHG) sink/source function. Until recently, most of the studies on the atmosphere-biosphere exchange of greenhouse gases from northern wetlands were short-term and seasonal. In 1998 the Peatland Carbon Study began continuous measurements of the carbon dynamics of a northern peatland and developed several ecosystem models to be used in simulations of the response of peatlands to climate variability and change. The continuous measurements have established the dominant role of climate variability in determining the magnitude and sign of the fluxes of GHGs. The Peatland Carbon Simulator (PCARS) was developed to use either direct measurements or modeled climate from a land surface process model such as the Canadian Land Surface Scheme (CLASS) which has been modified to incorporate the physical attributes of wetlands as inputs. PCARS illustrates the relative importance of various components of the ecosystem in determining the inter-annual variability in GHG exchange. Evaluation of PCARS has helped identify significant gaps in our knowledge of peatland systems. A second, more phenomenological model, the Peat Accumulation Model (PAM), demonstrates the overall importance of precipitation in controlling decadal to millennial scale variations in sink/source strength of CO_2. The Canadian Global Coupled Climate Carbon Model (CGC^3M) Network is attempting to parameterize wetland processes for the

  9. Characteristics of carbonaceous aerosols emitted from peatland fire in Riau, Sumatra, Indonesia (2): Identification of organic compounds

    NASA Astrophysics Data System (ADS)

    Fujii, Yusuke; Kawamoto, Haruo; Tohno, Susumu; Oda, Masafumi; Iriana, Windy; Lestari, Puji

    2015-06-01

    Smoke emitted from Indonesian peatland fires has caused dense haze and serious air pollution in Southeast Asia such as visibility impairment and adverse health impacts. To mitigate the Indonesian peatland fire aerosol impacts, an effective strategy and international framework based on the latest scientific knowledge needs to be established. Although several attempts have been made, limited data exist regarding the chemical characteristics of peatland fire smoke for the source apportionment. In order to identify the key organic compounds of peatland fire aerosols, we conducted intensive field studies based on ground-based and source-dominated sampling of PM2.5 in Riau Province, Sumatra, Indonesia, during the peatland fire seasons in 2012. Levoglucosan was the most abundant compound among the quantified organic compounds at 8.98 ± 2.28% of the PM2.5 mass, followed by palmitic acid at 0.782 ± 0.163% and mannosan at 0.607 ± 0.0861%. Potassium ion was not appropriate for an indicator of Indonesian peatland fires due to extremely low concentrations associated with smoldering fire at low temperatures. The vanillic/syringic acids ratio was 1.06 ± 0.155 in this study and this may be a useful signature profile for peatland fire emissions. Particulate n-alkanes also have potential for markers to identify impact of Indonesian peatland fire source at a receptor site.

  10. Land-Cover Change Within the Peatlands Along the Rocky Mountain Front, Montana: 1937-2009

    NASA Astrophysics Data System (ADS)

    Klene, A. E.; Milbrath, J. T.; Shelly, J. S.

    2013-12-01

    While peatlands are globally abundant, the fens of the Rocky Mountain Front (RMF), are the eastern-most, rich, peatlands in Montana, and are unique wetland habitats in this region of semi-arid continental climate. The peatlands provide critical riparian connectivity between the mountains and the plains and are habitat for grizzly bears, wolves, and within just the 450 ha Pine Butte Fen at least 93 species of vascular plants, including seven of Montana's Plant Species of Concern. Aerial photographs of the nine peatlands along the RMF in Montana were analyzed in a GIS. The boundary of each wetland was hand-digitized and the area within was classified into land-cover types: total area, open fen, open water, woody vegetation, and non-wetland/agriculture. Changes in wetland extent and land-cover categories were evaluated from the earliest available imagery in 1937 to the last available imagery in 2009. Images prior to 1995 were orthorectified, and all georectified. Climate change, wildlife, and agriculture were examined as potential drivers of land-cover change at these sites. Results indicate little change in overall peatland area between 1937 and 2009 despite increasing air temperatures in the region. Approximately 16% of these peatlands is 'open fen' and that proportion remained stable over the last seventy years. Area of open water quadrupled and the number of ponds which could be delineated tripled over the study period, reflecting a recovering beaver population. The non-wetland/agricultural area halved over the course of the study, primarily due to declines in agriculture within the three largest remaining peatlands: Pine Butte Fen, McDonald Swamp, and the Blackleaf Creek wetland complex. Most of the first two fens were purchased outright by the Nature Conservancy (TNC) and they hold a conservation easement on the third (as well as two other fens), all of which have been been put in place since the late 1970s. One fen is owned by the State of Montana and another

  11. Peatland carbon cycling and the implications of permafrost thaw; a chronosequence study.

    NASA Astrophysics Data System (ADS)

    Olefeldt, D.; Pelletier, N.; Talbot, J.; Blodau, C.; Turetsky, M. R.

    2015-12-01

    Peatlands in the Mackenzie River valley initiated ~9000 years ago and have built up vast soil carbon stores since. Peatland development history in this region is characterized by several distinct stages, varying in nutrient status and permafrost conditions. Widespread permafrost thaw has recently occurred in response to warming, thus making large soil C stores available for microbial processes and mineralization. A crucial question to answer is whether these peatland become net sinks or sources of C following thaw. The net response to thaw will either be dominated by new peat C accumulation at the surface or by mineralization of old peat C released from permafrost. In order to address this question we cored peat plateaus and nearby thermokarst bogs near Fort Simpson, Northwest Territories, representing 4 chronosequences. The cores were analyzed for C content, radiocarbon dates, macrofossils, testate amoebas, peat humification degree, elemental analysis, and microbial lability through an incubation experiment. Together, these approaches reveal peatland development histories, both before and following permafrost thaw. It is clear from our findings that C cycling following permafrost thaw will be intrinsically dependent on the developmental history of the peatland.

  12. The long-term fate of permafrost peatlands under rapid climate warming

    NASA Astrophysics Data System (ADS)

    Swindles, Graeme T.; Morris, Paul J.; Mullan, Donal; Watson, Elizabeth J.; Turner, T. Edward; Roland, Thomas P.; Amesbury, Matthew J.; Kokfelt, Ulla; Schoning, Kristian; Pratte, Steve; Gallego-Sala, Angela; Charman, Dan J.; Sanderson, Nicole; Garneau, Michelle; Carrivick, Jonathan L.; Woulds, Clare; Holden, Joseph; Parry, Lauren; Galloway, Jennifer M.

    2015-12-01

    Permafrost peatlands contain globally important amounts of soil organic carbon, owing to cold conditions which suppress anaerobic decomposition. However, climate warming and permafrost thaw threaten the stability of this carbon store. The ultimate fate of permafrost peatlands and their carbon stores is unclear because of complex feedbacks between peat accumulation, hydrology and vegetation. Field monitoring campaigns only span the last few decades and therefore provide an incomplete picture of permafrost peatland response to recent rapid warming. Here we use a high-resolution palaeoecological approach to understand the longer-term response of peatlands in contrasting states of permafrost degradation to recent rapid warming. At all sites we identify a drying trend until the late-twentieth century; however, two sites subsequently experienced a rapid shift to wetter conditions as permafrost thawed in response to climatic warming, culminating in collapse of the peat domes. Commonalities between study sites lead us to propose a five-phase model for permafrost peatland response to climatic warming. This model suggests a shared ecohydrological trajectory towards a common end point: inundated Arctic fen. Although carbon accumulation is rapid in such sites, saturated soil conditions are likely to cause elevated methane emissions that have implications for climate-feedback mechanisms.

  13. Permafrost peatland dynamics during the last millennia in NE European Russia and Finnish Lapland

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Väliranta, Minna; Piilo, Sanna; Amesbury, Matthew; Gallego-Sala, Angela; Charman, Dan

    2016-04-01

    Permafrost peatlands cover vast areas in circum-Arctic regions. Since the 1980s, annual temperatures in these areas have risen by ca. 2 °C and warming is projected to continue. Accordingly, the large carbon store in these peatlands may therefore be threatened. Alternatively, warming may increase productivity more than decomposition and peat accumulation rates may increase. To better understand how high latitude permafrost peatlands have responded to recent warming and what might be their future fate, we carried out detailed studies on two permafrost peatlands in NE Russia and two in Finnish Lapland. Our study methods included high resolution testate amoeba, plant macrofossil, C/N analyses, together with 210Pb and radiocarbon dating. We reconstructed changes in hydrological conditions, plant composition, and peat and carbon accumulation rates. Our preliminary results showed large variations in peat accumulation rates even within a very small area. Furthermore, testate amoeba and plant macrofossil data suggest variations in hydrological conditions during the last millennia. In the future, we will compare our regional data derived from different peatlands to each other, to climate reconstructions and to measured meteorological data.

  14. Seasonal changes in dominant bacterial taxa from acidic peatlands of the Atlantic Rain Forest.

    PubMed

    Etto, Rafael Mazer; Cruz, Leonardo Magalhães; da Conceição Jesus, Ederson; Galvão, Carolina Weigert; Galvão, Franklin; de Souza, Emanuel Maltempi; de Oliveira Pedrosa, Fábio; Reynaud Steffens, Maria Berenice

    2014-09-01

    The acidic peatlands of southern Brazil are essential for maintenance of the Atlantic Rain Forest, one of the 25 hot-spots of biodiversity in the world. While these ecosystems are closely linked to conservation issues, their microbial community ecology and composition remain unknown. In this work, histosol samples were collected from three acidic peatland regions during dry and rainy seasons and their chemical and microbial characteristics were evaluated. Culturing and culture-independent approaches based on SSU rRNA gene pyrosequencing were used to survey the bacterial community and to identify environmental factors affecting the biodiversity and microbial metabolic potential of the Brazilian peatlands. All acidic peatlands were dominated by the Acidobacteria phylum (56-22%) followed by Proteobacteria (28-12%). The OTU richness of these phyla and the abundance of their Gp1, Gp2, Gp3, Gp13, Rhodospirillales and Caulobacteriales members varied according to the period of collection and significantly correlated with the rainy season. However, despite changes in acidobacterial and proteobacterial communities, rainfall did not affect the microbial metabolic potential of the southern Brazilian Atlantic Rain Forest peatlands, as judged by the metabolic capabilities of the microbial community. PMID:24893336

  15. The long-term fate of permafrost peatlands under rapid climate warming

    PubMed Central

    Swindles, Graeme T.; Morris, Paul J.; Mullan, Donal; Watson, Elizabeth J.; Turner, T. Edward; Roland, Thomas P.; Amesbury, Matthew J.; Kokfelt, Ulla; Schoning, Kristian; Pratte, Steve; Gallego-Sala, Angela; Charman, Dan J.; Sanderson, Nicole; Garneau, Michelle; Carrivick, Jonathan L.; Woulds, Clare; Holden, Joseph; Parry, Lauren; Galloway, Jennifer M.

    2015-01-01

    Permafrost peatlands contain globally important amounts of soil organic carbon, owing to cold conditions which suppress anaerobic decomposition. However, climate warming and permafrost thaw threaten the stability of this carbon store. The ultimate fate of permafrost peatlands and their carbon stores is unclear because of complex feedbacks between peat accumulation, hydrology and vegetation. Field monitoring campaigns only span the last few decades and therefore provide an incomplete picture of permafrost peatland response to recent rapid warming. Here we use a high-resolution palaeoecological approach to understand the longer-term response of peatlands in contrasting states of permafrost degradation to recent rapid warming. At all sites we identify a drying trend until the late-twentieth century; however, two sites subsequently experienced a rapid shift to wetter conditions as permafrost thawed in response to climatic warming, culminating in collapse of the peat domes. Commonalities between study sites lead us to propose a five-phase model for permafrost peatland response to climatic warming. This model suggests a shared ecohydrological trajectory towards a common end point: inundated Arctic fen. Although carbon accumulation is rapid in such sites, saturated soil conditions are likely to cause elevated methane emissions that have implications for climate-feedback mechanisms. PMID:26647837

  16. The long-term fate of permafrost peatlands under rapid climate warming.

    PubMed

    Swindles, Graeme T; Morris, Paul J; Mullan, Donal; Watson, Elizabeth J; Turner, T Edward; Roland, Thomas P; Amesbury, Matthew J; Kokfelt, Ulla; Schoning, Kristian; Pratte, Steve; Gallego-Sala, Angela; Charman, Dan J; Sanderson, Nicole; Garneau, Michelle; Carrivick, Jonathan L; Woulds, Clare; Holden, Joseph; Parry, Lauren; Galloway, Jennifer M

    2015-01-01

    Permafrost peatlands contain globally important amounts of soil organic carbon, owing to cold conditions which suppress anaerobic decomposition. However, climate warming and permafrost thaw threaten the stability of this carbon store. The ultimate fate of permafrost peatlands and their carbon stores is unclear because of complex feedbacks between peat accumulation, hydrology and vegetation. Field monitoring campaigns only span the last few decades and therefore provide an incomplete picture of permafrost peatland response to recent rapid warming. Here we use a high-resolution palaeoecological approach to understand the longer-term response of peatlands in contrasting states of permafrost degradation to recent rapid warming. At all sites we identify a drying trend until the late-twentieth century; however, two sites subsequently experienced a rapid shift to wetter conditions as permafrost thawed in response to climatic warming, culminating in collapse of the peat domes. Commonalities between study sites lead us to propose a five-phase model for permafrost peatland response to climatic warming. This model suggests a shared ecohydrological trajectory towards a common end point: inundated Arctic fen. Although carbon accumulation is rapid in such sites, saturated soil conditions are likely to cause elevated methane emissions that have implications for climate-feedback mechanisms. PMID:26647837

  17. Manure derived biochar can successfully replace phosphate rock amendment in peatland restoration.

    PubMed

    Pouliot, Rémy; Hugron, Sandrine; Rochefort, Line; Godbout, Stéphane; Palacios, Joahnn H; Groeneveld, Elisabeth; Jarry, Isabelle

    2015-07-01

    Phosphate rock fertilization is commonly used in peatland restoration to promote the growth of Polytrichum strictum, a nurse plant which aids the establishment of Sphagnum mosses. The present study tested whether 1) phosphorus fertilization facilitates the germination of P. strictum spores and 2) biochar derived from local pig manure can replace imported phosphate rock currently used in peatland restoration. Various doses of biochar were compared to phosphate rock to test its effect directly on P. strictum stem regeneration (in Petri dishes in a growth chamber) and in a simulation of peatland restoration with the moss layer transfer technique (in mesocoms in a greenhouse). Phosphorus fertilization promoted the germination of P. strictum spores as well as vegetative stem development. Biochar can effectively replace phosphate rock in peatland restoration giving a new waste management option for rural regions with phosphorus surpluses. As more available phosphorus was present in biochar, an addition of only 3-9 g m(-2) of pig manure biochar is recommended during the peatland restoration process, which is less than the standard dose of phosphate rock (15 g m(-2)). PMID:25897506

  18. Natural zinc enrichment in peatlands: Biogeochemistry of ZnS formation

    NASA Astrophysics Data System (ADS)

    Yoon, Soh-joung; Yáñez, Carolina; Bruns, Mary Ann; Martínez-Villegas, Nadia; Martínez, Carmen Enid

    2012-05-01

    Peatlands effectively retain heavy metals and prevent stream and watershed contamination. Sulfate reduction is considered the most significant process of metal immobilization in natural wetlands and microbial sulfate reduction is the presumed mechanism that results in the precipitation of metal sulfides. In this study, we examined the biogeochemical mechanisms involved in zinc retention and accumulation in a metalliferous peatland of western New York. In the reducing conditions of these peatlands zinc sulfides occurred as framboidal aggregates of sphalerite and polytypic wurtzite (2nH, n ⩾ 2) nanocrystallites associated with bacterial cells and organic matter. Bacterial cells were co-located with ZnS inside peat particles where the microenvironment remained anoxic. The peat zinc sulfide was depleted in 34S isotopes relative to the sulfate supplied to the peatland by 18-34 per mill, implicating its biological formation. Extraction of microbial community DNA from peat samples yielded diverse PCR amplicons from dissimilatory sulfite reductase (dsrAB) genes, indicating varied bacterial taxa capable of reducing forms of oxidized sulfur. Nanocrystals with distinct structural features were observed in samples containing contrasting dsrAB sequences. The results of this investigation provide clear evidence that microorganisms can influence the chemical forms of heavy metals in peatland environments. Our findings also provide insight into the conditions necessary to promote the immobilization of chalcophile elements in engineered systems for the treatment of acid mine drainage and wastewater effluents.

  19. The flux of organic matter through a peatland ecosystem - evidence from thermogravimetric analysis

    NASA Astrophysics Data System (ADS)

    Worrall, Fred; Moody, Catherine; Clay, Gareth

    2016-04-01

    Carbon budgets of peatlands are now common and studies have considered nitrogen, oxygen and energy budgets, but no study has considered the whole composition of the organic matter as it transfers through and into a peatland. Organic matter samples were taken from each organic matter reservoir found in and each fluvial flux from a peatland and analysed the samples by thermogravimetric analysis. The samples analysed were: aboveground, belowground, heather, mosses and sedges, litter layer, a peat core, and monthly samples of particulate and dissolved organic matter. All organic matter samples were taken from a 100% peat catchment within Moor House National Nature Reserve in the North Pennines, UK, and collected samples were compared to standards of lignin, cellulose, humic acid and plant protein. Results showed that the thermogravimetric trace of the sampled organic matter were distinctive with the DOM traces being marked out by very low thermal stability relative other organic matter types. The peat profile shows a significant trend with depth from vegetation- to lignin-like composition. When all traces are weighted according to the observed dry matter and carbon budgets for the catchment then it is possible to judge what has been lost in the transition through and into the ecosystem. By plotting this "lost" trace it possible to assess its composition which is either 97% cellulose and 3% humic acid or 92% and 8% lignin. This has important implications for what controls the organic matter balance of peatlands and it suggests that the oxidation state (OR) of peatland is less than 1.

  20. Spatial patterns of denitrification and its functional genes in peatlands

    NASA Astrophysics Data System (ADS)

    Mander, Ülo; Ligi, Teele; Truu, Marika; Truu, Jaak; Pärn, Jaan; Egorov, Sergey; Järveoja, Järvi; Vohla, Christina; Maddison, Martin; Soosaar, Kaido; Oopkaup, Kristjan; Teemusk, Alar; Preem, Jens-Konrad; Uuemaa, Evelyn

    2014-05-01

    This study is aimed to analyse relationships between the environmental factors and the spatial distribution of the main functional genes nirS, nirK, and nosZ regulating the denitrification process. Variations in hydrological regime, soil temperature and peat quality have been taken into the consideration at both local and global scale. Measurements of greenhouse gas (GHG) emissions using static chambers, groundwater analysis, gas and peat sampling for further laboratory analysis has been conducted in various peatlands in Iceland (two study areas, 2011), Transylvania/Romania (2012), Santa Catarina/Brazil (2012), Quebec/Canada (2012), Bashkortostan/Russian Federation (two study areas, 2012), Sichuan/China (2012), Estonia (two study areas, 2012), Florida/USA (2013, Sologne/France (2013), Jugra in West Siberia/Russia (2013), Uganda (2013), French Guyana (two study areas, 2013), Tasmania (two study areas, 2014) and New Zealand (two study areas, 2014). In each study area at least 2 transects along the groundwater depth gradient, one preferably in undisturbed, another one in drained area, and at least 3 rows of sampling sites (3-5 replicate chambers and 1 piezometer and soil sampling plot in each) in both has been established for studies. In each transect GHG emission was measured during 2-3 days in at least 5 sessions. In addition, organic sediments from the artificial riverine wetlands in Ohio/USA in 2009 and relevant gas emission studies have been used in the analyses. In the laboratories of Estonian University of Life Sciences and the University of Tartu, the peat chemical quality (pH, N, P, C, NH4, NO3) and N2O, CO2, and CH4 concentration in gas samples (50mL glass bottles and exetainers) were analysed. The peat samples for further pyrosequencing and qPCR analyses are stored in fridge by -22oC. This presentation will consider the variation of GHG emissions and hydrological conditions in the study sites. In addition, several selected biophysical factors will be taken

  1. High diversity of tropical peatland ecosystem types in the Pastaza-Marañón basin, Peruvian Amazonia

    NASA Astrophysics Data System (ADS)

    LäHteenoja, Outi; Page, Susan

    2011-06-01

    Very little information exists on Amazonian peatlands with most studies on tropical peatlands concentrating on Southeast Asia. Here we describe diversity of Amazonian peatland ecosystems and consider its implications for the global diversity of tropical peatland ecosystems. Nine study sites were selected from within the most extensive wetland area of Peruvian Amazonia: the 120,000 km2 Pastaza-Marañón basin. Peat thickness was determined every 500 m from the edge toward the center of each site, and peat samples were collected from two cores per site. Samples from the entire central core and surface samples from the other core were analyzed for nutrient content. Topography of four peat deposits was measured. In order to study differences in vegetation, pixel values were extracted from a satellite image. The surface peat nutrient content of the peatlands varied from very nutrient-rich to nutrient-poor. Two of the peatlands measured for their topography were domed (5.4 and 5.8 m above the stream), one was gently sloping (1.4 m above the stream), and one was flat and occurred behind a 7 m high levee. Five different peatland vegetation types were detected on the basis of pixel values derived from the satellite image. The peat cores had considerable variation in nutrient content and showed different developmental pathways. In summary, the Pastaza-Marañón basin harbors a considerable diversity of previously undescribed peatland ecosystems, representing a gradient from atmosphere-influenced, nutrient-poor ombrotrophic bogs through to river-influenced, nutrient-rich swamps. Their existence affects the habitat diversity, carbon dynamics, and hydrology of the Amazonian lowlands, and they also provide an undisturbed analog for the heavily disturbed peatlands of Southeast Asia. Considering the factors threatening the Amazonian lowlands, there is an urgent need to investigate and conserve these peatland ecosystems, which may in the near future be among the very few

  2. An improved description of soil hydraulic and thermal properties of arctic peatland for use in a GCM

    NASA Astrophysics Data System (ADS)

    Hall, Robin L.; Huntingford, Chris; Harding, Richard J.; Lloyd, Colin R.; Cox, Peter M.

    2003-09-01

    The UK Meteorological Office Surface Exchange Scheme (MOSES), which is currently implemented within Version 3 of the Hadley Centre GCM, was tested for an arctic peatland site in northern Finland (Kevo). This implementation of MOSES incorporated a new depth-dependent parameterization of the thermal and hydraulic properties of peat with parameter values derived from measurements reported in the literature. The effect of increasing the number of model soil layers from four to 13 shallower layers was also investigated. Driving data were used that were collected during June, when the peat was still frozen below about 80 mm, to September 1997.Best model performance was given by the 13-layer, depth-dependent parameter description for both surface heat fluxes and soil temperatures. The simulated heat fluxes compared well with measurements, but simulated surface temperatures were too high. In preliminary runs the simulated distribution of unfrozen water in the soil was also unrealistic. In particular the model was unable to predict the rapid transition to above-freezing conditions that occurred throughout the soil profile about the second week in July. Adjusting a parameter (k) of the soil-freezing curve, which for peat can be used as a fitting parameter, produced a big improvement in the soil temperature profiles. A more accurate simulation of the freezing and thawing behaviour of organic soils requires that the processes that are hidden in the modified value of k are explicitly represented. Copyright

  3. The 5.2 ka climate event: Evidence from stable isotope and multi-proxy palaeoecological peatland records in Ireland

    NASA Astrophysics Data System (ADS)

    Roland, T. P.; Daley, T. J.; Caseldine, C. J.; Charman, D. J.; Turney, C. S. M.; Amesbury, M. J.; Thompson, G. J.; Woodley, E. J.

    2015-09-01

    Evidence for a major climate event at 5.2 ka has been reported globally and is associated with considerable societal disruption, but is poorly characterised in northwest Europe. This event forms part of a broader period of re-organisation in the Earth's ocean-atmosphere circulation system between 6 and 5 ka. This study tests the nature and timing of the event in northwest Europe, a region highly sensitive to change in meridional overturning circulation and mid-latitude westerly airflow. Here we report three high-resolution Irish multi-proxy records obtained from ombrotrophic peatlands that have robust chronological frameworks. We identify the 5.2 ka event by a sustained decrease in δ18Ocellulose at all three sites, with additional and parallel changes in δ13Ccellulose and palaeoecological (testate amoebae, plant macrofossil and humification) data from two sites in northern Ireland. Data from Sluggan Moss demonstrate a particularly coherent shift towards wetter conditions. These data support the hypothesis that the event was caused by a prolonged period of positive North Atlantic Oscillation conditions, resulting in pervasive cyclonic weather patterns across northwest Europe, increasing precipitation over Ireland.

  4. [Nitrogen input altered testate amoebae community in peatland of Sanjiang Plain, Northeast China].

    PubMed

    Song, Li-hong; Yan, Xiu-min; Wang, Ke-hong; Zhu, Xiao-yan; Wu, Dong-hu

    2015-02-01

    In the present study, an in situ control experiment was carried out to explore the response of testate amoebae to exogenous nitrogen addition in peatland of Sanjiang Plain. The results showed that nitrogen addition increased the biomass of testate amoebae at lower levels (6 g N · m(-2)), while decreased it at higher levels (> 12 g N · m(-2)). At genus level, nitrogen addition significantly increased the biomass of Arcella and Phryganella, decreased the biomass of Euglypha. Only lower nitrogen addition significantly increased the biomass of Centropyxis. At species level, nitrogen addition significantly decreased the biomass of Euglypha rotunda, while the biomass of either Centropyxis cassis or Phryganella acropodia was increased by a lower nitrogen addition treatment. This study suggested that the response of peatland testate amoebae to nitrogen addition was species specific, which could potentially be used as an indicator for the environment of peatlands. PMID:26094475

  5. Aerobic and Anaerobic Respiration in Profiles of Polesie Lubelskie Peatlands

    NASA Astrophysics Data System (ADS)

    Szafranek-Nakonieczna, Anna; Stêpniewska, Zofia

    2014-04-01

    Soil respiration is a very important factor influencing carbon deposition in peat and reflecting the intensity of soil organic matter decomposition, root respiration, and the ease of transporting gases to the surface. Carbon dioxide release from three different peat soil profiles (0-80 cm) of the Polesie Lubelskie Region (Eastern Poland) was analyzed under laboratory conditions. Peat samples were incubated at 5, 10, and 20°C in aerobic and anaerobic environments, and their CO2-evolution was analyzed up to 14 days. The respiration activity was found to be in the range of 0.013-0.497 g CO2 kg-1 DW d-1. The respiratory quotient was estimated to be in the range of 0.51-1.51, and the difference in respiration rates over 10°C ranged between 4.15 and 8.72 in aerobic and from 1.15 to 6.53 in anaerobic conditions. A strong influence of temperature, depth, the degree of peat decomposition, pH, and nitrate content on respiration activity was found. Lack of oxygen at low temperature caused higher respiration activity than under aerobic conditions. These results should be taken into account when the management of Polish peatlands is considered in the context of climate and carbon storage, and physicochemical properties of soil in relation to soil respiration activity are considered.

  6. Climate change impact on peatland and forest ecosystems of Russia

    SciTech Connect

    Kondrasheva, N.Yu.; Kobak, K.I.; Turchinovich, I.Ye.

    1996-12-31

    Paleoclimatic and paleobotanic reconstructions allow a conclusion that ecosystems and natural zones significantly changed due to climate fluctuations. The average long-term carbon accumulation in peatlands of Russia was estimated as 45.6 mln tons of carbon per year. During the Holocene the rate of peat accumulation changed. During the Subboreal period the rate of peat accumulation gradually decreased to 17 gC/m2 yr, reaching its lowest value in the Subatlantic period. Apparently, the rate of peat accumulation decreased in Subboreal period due to sharp cooling and precipitation decrease. Future rates of peat accumulation might be higher than the present one. Forest ecosystems of north-western Russia also significantly changed during the Holocene. In Atlantic time the boundary between middle and south taiga was located 500 km northward compared to the present and broad-leaved forest occupied large areas. According to their forecast, a mean global air temperature increase by 1.4 C is expected to result in a considerable decrease in coniferous forest area and an increase in mixed and broad-leaved forest area.

  7. The carbon functional group budget of a peatland

    NASA Astrophysics Data System (ADS)

    Moody, Catherine; Worrall, Fred; Clay, Gareth; Apperley, David

    2016-04-01

    Organic matter samples were taken from each organic matter reservoir and fluvial flux found in a peatland and analysed by elemental analysis for carbon, hydrogen, nitrogen and oxygen content, and by 13C solid state nuclear magnetic resonance (NMR) for functional group composition. The samples analysed were: aboveground, belowground, heather, mosses and sedges, litter layer, four different depths from a peat core, and monthly samples of fluvial particulate and dissolved organic matter. All organic matter samples were taken from a 100% peat catchment within Moor House National Nature Reserve in the North Pennines, UK. The proportion of carbon atoms from each of the eight carbon functional groups (C-alkyl, N-alkyl/methoxyl C, O-alkyl, O2-alkyl/acetal C, aromatic/unsaturated C, phenolic C, aldehyde/ketone C and amide/carboxyl C) from each type of organic matter were combined with an existing carbon budget from the same site, to give a functional group carbon budget. The budget results show that the ecosystem is accumulating N-alkyl/methoxyl C, O-alkyl, O2-alkyl/acetal C and phenolic C groups, but losing C-alkyl, aromatic/unsaturated C, amide/carboxyl C and aldehyde/ketone C. Comparing the functional group compositions between the sampled organic matter pools shows that DOM arises from two distinct sources; from the peat itself and from a vegetation source.

  8. Peatlands and green frogs: A relationship regulated by acidity?

    USGS Publications Warehouse

    Mazerolle, M.J.

    2005-01-01

    The effects of site acidification on amphibian populations have been thoroughly addressed in the last decades. However, amphibians in naturally acidic environments, such as peatlands facing pressure from the peat mining industry, have received little attention. Through two field studies and an experiment, I assessed the use of bog habitats by the green frog (Rana clamitans melanota), a species sensitive to various forestry and peat mining disturbances. First, I compared the occurrence and breeding patterns of frogs in bog and upland ponds. I then evaluated frog movements between forest and bog habitats to determine whether they corresponded to breeding or postbreeding movements. Finally, I investigated, through a field experiment, the value of bogs as rehydrating areas for amphibians by offering living Sphagnum moss and two media associated with uplands (i.e., water with pH ca 6.5 and water-saturated soil) to acutely dehydrated frogs. Green frog reproduction at bog ponds was a rare event, and no net movements occurred between forest and bog habitats. However, acutely dehydrated frogs did not avoid Sphagnum. Results show that although green frogs rarely breed in bogs and do not move en masse between forest and bog habitats, they do not avoid bog substrates for rehydrating, despite their acidity. Thus, bogs offer viable summering habitat to amphibians, which highlights the value of these threatened environments in terrestrial amphibian ecology.

  9. Hydrological factors behind the water quality changes due to restoration in boreal peatlands

    NASA Astrophysics Data System (ADS)

    Ronkanen, Anna-Kaisa; Marttila, Hannu; Walle Menberu, Meseret; Irannezhad, Masoud; Tahvanainen, Teemu; Penttinen, Jouni; Hokkanen, Reijo; Klöve, Björn

    2016-04-01

    Recovery of hydrological conditions after restoration in previously drained peatlands is typically faster process compared to changes in runoff water quality. Often nutrient load from restored sites increase remarkably during restoration operation and reduce over time when conditions stabilize. However, in some sites nutrient load can remain high for long periods of time which increase negative effects of restoration on downstream water bodies. The factors and challenges behind these processes are poorly understood in practical catchment restoration planning. This study aims to understand factors affecting water quality changes after peatland restoration. Totally 43 peatlands areas of which 24 sites were previously drained and restored during the study and 19 sites at their pristine stage (control sites) were included to the study. The control pristine sites had as little anthropogenic disturbances as possible and the sites were chosen so that the paired study sites closely share similar peatland type, nutrient status and weather conditions. Pore water quality (total phosphorus, total nitrogen, dissolved organic carbon, pH, electric conductivity and colour) was measured from all sites and runoff quality and amount from 7 sites in the years 2008-2014. Measured parameters, different peatland types and nutrient loads were studied together with numerous hydrological parameters (variation in water table fluctuations, peat pore water recharge coefficient, physical parameters of peat e.g. specific yield, degree of humification) by statistical methods. Differences in water table dependent hydrological conditions indicate e.g. flow paths and residence time of water that is known to have effect on runoff water quality. As a result, water table related hydrological changes following restoration are as well assumed to explain alterations in water quality in different peatland types. In addition, using water table related hydrological processes as a proxy for water quality

  10. The Utility of Fire Radiative Energy for Understanding Fuel Consumption due to Wildfire in Boreal Peatlands

    NASA Astrophysics Data System (ADS)

    Banskota, A.; Falkowski, M. J.; Kane, E. S.; Smith, A. M.

    2014-12-01

    Radiative energy from active fire has been found to correlate well with the amount of fuel consumed during the lifetime of a fire event. Fire radiative power (FRP) detected by sensors onboard MODIS satellites may therefore provide direct estimates of CO2 emissions related to biomass burning. Less known is the ability of satellite data to detect active fire from predominantly smoldering burns in boreal peatlands. Boreal peatlands store a large amount of soil carbon that is likely to become increasingly vulnerable to wildfire as climate change lowers water tables and exposes C-rich peat to burning. In this study, we investigate the utility of fire radiative energy (FRE) to estimate fuel consumption associated with wildfire in 2004 in boreal peatlands in Alaska. FRE values are generally estimated from FRP retrieved at detected active fire locations and times by summing the FRP values multiplied by the time difference between acquisitions. One central issue in deriving reliable FRE estimates by such approach is the requirement for sufficient sampling of the FRP to capture spatiotemporal variability in the fire. Our preliminary analysis confirms that the detection of active fire in peatlands are indeed not spatially exhaustive and temporally continuous. Thus we are further investigating the fusion of instantaneous FRP from MODIS active fire detection with the MODIS burned area product to derive FRE estimates across the burned area. We are following a previously tested strategy for such fusion for temporal integration of instantaneous FRP to derive FRE and spatial extrapolation of FRE over the burned area. The FRE estimates are then related to ground-measured peatland burn depths across different wildfire locations. The results of this study will ultimately indicate the utility of MODIS fire products for providing reliable biomass burned estimates in boreal peatlands.

  11. Biogeophysical impacts of peatland forestation on regional climate changes in Finland

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Markkanen, T.; Backman, L.; Henttonen, H. M.; Pietikäinen, J.-P.; Mäkelä, H. M.; Laaksonen, A.

    2014-12-01

    Land cover changes can impact the climate by influencing the surface energy and water balance. Naturally treeless or sparsely treed peatlands were extensively drained to stimulate forest growth in Finland over the second half of 20th century. The aim of this study is to investigate the biogeophysical effects of peatland forestation on regional climate in Finland. Two sets of 18-year climate simulations were done with the regional climate model REMO by using land cover data based on pre-drainage (1920s) and post-drainage (2000s) Finnish national forest inventories. In the most intensive peatland forestation area, located in the middle west of Finland, the results show a warming in April of up to 0.43 K in monthly-averaged daily mean 2 m air temperature, whereas a slight cooling from May to October of less than 0.1 K in general is found. Consequently, snow clearance days over that area are advanced up to 5 days in the mean of 15 years. No clear signal is found for precipitation. Through analysing the simulated temperature and energy balance terms, as well as snow depth over five selected subregions, a positive feedback induced by peatland forestation is found between decreased surface albedo and increased surface air temperature in the snow-melting period. Our modelled results show good qualitative agreements with the observational data. In general, decreased surface albedo in the snow-melting period and increased evapotranspiration in the growing period are the most important biogeophysical aspects induced by peatland forestation that cause changes in climate. The results from this study can be further integrally analysed with biogeochemical effects of peatland forestation to provide background information for adapting future forest management to mitigate climate warming effects. Moreover, they provide insights about the impacts of projected forestation of tundra at high latitudes due to climate change.

  12. Permafrost conditions in peatlands regulate magnitude, timing, and chemical composition of catchment dissolved organic carbon export.

    PubMed

    Olefeldt, David; Roulet, Nigel T

    2014-10-01

    Permafrost thaw in peatlands has the potential to alter catchment export of dissolved organic carbon (DOC) and thus influence downstream aquatic C cycling. Subarctic peatlands are often mosaics of different peatland types, where permafrost conditions regulate the hydrological setting of each type. We show that hydrological setting is key to observed differences in magnitude, timing, and chemical composition of DOC export between permafrost and nonpermafrost peatland types, and that these differences influence the export of DOC of larger catchments even when peatlands are minor catchment components. In many aspects, DOC export from a studied peatland permafrost plateau was similar to that of a forested upland catchment. Similarities included low annual export (2-3 g C m(-2) ) dominated by the snow melt period (~70%), and how substantial DOC export following storms required wet antecedent conditions. Conversely, nonpermafrost fens had higher DOC export (7 g C m(-2) ), resulting from sustained hydrological connectivity during summer. Chemical composition of catchment DOC export arose from the mixing of highly aromatic DOC from organic soils from permafrost plateau soil water and upland forest surface horizons with nonaromatic DOC from mineral soil groundwater, but was further modulated by fens. Increasing aromaticity from fen inflow to outlet was substantial and depended on both water residence time and water temperature. The role of fens as catchment biogeochemical hotspots was further emphasized by their capacity for sulfate retention. As a result of fen characteristics, a 4% fen cover in a mixed catchment was responsible for 34% higher DOC export, 50% higher DOC concentrations and ~10% higher DOC aromaticity at the catchment outlet during summer compared to a nonpeatland upland catchment. Expansion of fens due to thaw thus has potential to influence landscape C cycling by increasing fen capacity to act as biogeochemical hotspots, amplifying aquatic C cycling, and

  13. Environmental correlates of peatland carbon fluxes in a thawing landscape: do transitional thaw stages matter?

    NASA Astrophysics Data System (ADS)

    Malhotra, A.; Roulet, N. T.

    2015-01-01

    Peatlands in discontinuous permafrost regions occur as a mosaic of wetland types, each with variable sensitivity to climate change. Permafrost thaw further increases the spatial heterogeneity in ecosystem structure and function in peatlands. Carbon (C) fluxes are well characterized in end-member thaw stages such as fully intact or fully thawed permafrost but remain unconstrained for transitional stages that cover a significant area of thawing peatlands. Furthermore, changes in the environmental correlates of C fluxes, due to thaw are not well described: a requirement for modeling future changes to C storage of permafrost peatlands. We investigated C fluxes and their correlates in end-member and a number of transitional thaw stages in a sub-arctic peatland. Across peatland lumped CH4 and CO2 flux data had significant correlations with expected correlates such as water table depth, thaw depth, temperature, photosynthetically active radiation and vascular green area. Within individual thaw states, bivariate correlations as well as multiple regressions between C flux and environmental factors changed variably with increasing thaw. The variability in directions and magnitudes of correlates reflects the range of structural conditions that could be present along a thaw gradient. These structural changes correspond to changes in C flux controls, such as temperature and moisture, and their interactions. Temperature sensitivity of CH4 increased with increasing thaw in bivariate analyses, but lack of this trend in multiple regression analyses suggested cofounding effects of substrate or water limitation on the apparent temperature sensitivity. Our results emphasize the importance of incorporating transitional stages of thaw in landscape level C budgets and highlight that end-member or adjacent thaw stages do not adequately describe the variability in structure-function relationships present along a thaw gradient.

  14. Environmental correlates of peatland carbon fluxes in a thawing landscape: do transitional thaw stages matter?

    NASA Astrophysics Data System (ADS)

    Malhotra, A.; Roulet, N. T.

    2015-05-01

    Peatlands in discontinuous permafrost regions occur as a mosaic of wetland types, each with variable sensitivity to climate change. Permafrost thaw further increases the spatial heterogeneity in ecosystem structure and function in peatlands. Carbon (C) fluxes are well characterized in end-member thaw stages such as fully intact or fully thawed permafrost but remain unconstrained for transitional stages that cover a significant area of thawing peatlands. Furthermore, changes in the environmental correlates of C fluxes, due to thaw, are not well described - a requirement for modeling future changes to C storage of permafrost peatlands. We investigated C fluxes and their correlates in end-member and a number of transitional thaw stages in a sub-arctic peatland. Across peatland-lumped CH4 and CO2 flux data had significant correlations with expected correlates such as water table depth, thaw depth, temperature, photosynthetically active radiation and vascular green area. Within individual thaw states, bivariate correlations as well as multiple regressions between C flux and environmental factors changed variably with increasing thaw. The variability in directions and magnitudes of correlates reflects the range of structural conditions that could be present along a thaw gradient. These structural changes correspond to changes in C flux controls, such as temperature and moisture, and their interactions. Temperature sensitivity of CH4 increased with increasing thaw in bivariate analyses, but lack of this trend in multiple regression analyses suggested cofounding effects of substrate or water limitation on the apparent temperature sensitivity. Our results emphasize the importance of incorporating transitional stages of thaw in landscape level C budgets and highlight that end-member or adjacent thaw stages do not adequately describe the variability in structure-function relationships present along a thaw gradient.

  15. Disappearance of Relict Permafrost in Boreal North America: Effects on Peatland Carbon Storage and Fluxes

    SciTech Connect

    Turetsky, M. R.; Wieder, R. K.; Vitt, D. H.; Evans, R. J.; Scott, K. D.

    2007-01-01

    Boreal peatlands in Canada have harbored relict permafrost since the Little Ice Age due to the strong insulating properties of peat. Ongoing climate change has triggered widespread degradation of localized permafrost in peatlands across continental Canada. Here, we explore the influence of differing permafrost regimes (bogs with no surface permafrost, localized permafrost features with surface permafrost, and internal lawns representing areas of permafrost degradation) on rates of peat accumulation at the southernmost limit of permafrost in continental Canada. Net organic matter accumulation generally was greater in unfrozen bogs and internal lawns than in the permafrost landforms, suggesting that surface permafrost inhibits peat accumulation and that degradation of surface permafrost stimulates net carbon storage in peatlands. To determine whether differences in substrate quality across permafrost regimes control trace gas emissions to the atmosphere, we used a reciprocal transplant study to experimentally evaluate environmental versus substrate controls on carbon emissions from bog, internal lawn, and permafrost peat. Emissions of CO{sub 2} were highest from peat incubated in the localized permafrost feature, suggesting that slow organic matter accumulation rates are due, at least in part, to rapid decomposition in surface permafrost peat. Emissions of CH{sub 4} were greatest from peat incubated in the internal lawn, regardless of peat type. Localized permafrost features in peatlands represent relict surface permafrost in disequilibrium with the current climate of boreal North America, and therefore are extremely sensitive to ongoing and future climate change. Our results suggest that the loss of surface permafrost in peatlands increases net carbon storage as peat, though in terms of radiative forcing, increased CH{sub 4} emissions to the atmosphere will partially or even completely offset this enhanced peatland carbon sink for at least 70 years following

  16. Impacts of drain blocking on the aquatic carbon export from a UK peatland

    NASA Astrophysics Data System (ADS)

    Leith, Fraser; Dinsmore, Kerry; Carfrae, Jennifer

    2016-04-01

    Drainage ditches, which have historically been used across UK peatlands, provide a rapid pathway for carbon export between terrestrial and aquatic systems, potentially reducing or reversing the net uptake of carbon by peatlands. Currently, considerable investment is being made in Scotland to restore drained peatlands with the aim of raising water tables, restoring active vegetation cover, enhancing carbon uptake and reducing carbon losses via the aquatic pathway. However, monitoring of restoration and its impact is often restricted by a lack of pre-restoration data and typically does not cover the full range of fluvial carbon species. Drain blocking was carried out in March 2015 at the Auchencorth Moss peatland, SE Scotland, which has an extensive record of fluvial carbon measurements (from 2007 to present day). This study combines an intensive 12 month field monitoring campaign, during and after drain blocking works, with the long-term record to investigate the impacts of drain blocking on the dissolved and gaseous carbon export via the aquatic pathway. Post-restoration, concentrations and fluxes of all stream water dissolved and gaseous carbon species were in the range of values measured over the period 2007 to present; with no significant change in the 12 months post-restoration. The results from this study indicate that the drain blocking works did not have a significant impact on the concentration or speciation of carbon exported via the aquatic pathway which can be attributed to the largely overgrown nature of the drains and the large inter- and intra-annual variability in the system. This study raises questions on the suitability of some peatlands for drain blocking and the pre- and post-restoration monitoring required to accurately assess the impacts of peatland restoration activities.

  17. Aquatic carbon export from peatland catchments recently undergone wind farm development

    NASA Astrophysics Data System (ADS)

    Smith, Ben; Waldron, Susan; Henderson, Andrew; Flowers, Hugh; Gilvear, David

    2013-04-01

    Scotland's peat landscapes are desirable locations for wind-based renewables due to high wind resources and low land use pressures in these areas. The environmental impact of sitting wind-based renewables on peats however, is unknown. Globally, peatlands are important terrestrial carbon stores. Given the topical nature of carbon-related issues, e.g. global warming and carbon footprints, it is imperative we help mitigate their degradation and maintain carbon sequestration. To do so, we need to better understand how peatland systems function with regards to their carbon balance (export versus sequestration) so we can assess their resilience and adaptation to hosting land-based renewable energy projects. Predicting carbon lost as a result of construction of wind farms built on peatland has not been fully characterised and this research will provide data that can supplement current 'carbon payback calculator' models for wind farms that aim to reinforce their 'green' credentials. Transfer of carbon from the terrestrial peatland systems to the aquatic freshwater and oceanic systems is most predominant during periods of high rainfall. It has been estimated that 50% of carbon is exported during only 10% of highest river flows, (Hinton et al., 1998). Furthermore, carbon export from peatlands is known to have a seasonal aspect with highest concentrations of dissolved organic carbon (DOC) found mostly in late summer months of August and September and lowest in December and January, (Dawson et al., 2004). Event sampling, where high intensity sample collection is carried out during high river flow periods, offers a better insight, understanding and estimation of carbon aquatic fluxes from peatland landscapes. The Gordonbush estate, near Brora, has an extensive peatland area where a wind farm development has recently been completed (April 2012). Investigations of aquatic carbon fluxes from this peatland system were started in July 2010, in conjunction with the start of

  18. A multi-tracer approach to determine groundwater discharge patterns in pristine peatlands

    NASA Astrophysics Data System (ADS)

    Isokangas, Elina; Rossi, Pekka; Kløve, Bjørn

    2014-05-01

    Changes in water flow patterns (e.g. due to ditching or pumping water) in the vicinity of a peatland can affect its hydrology and ecology irreversibly. In Finland esker aquifers, often used for water abstraction, discharge groundwater typically to peatlands. Locations of these discharge zones are important for understanding peatland hydrology and ecology in general and for predicting the impacts of groundwater abstraction. In this study, a Finnish pristine peatland connected to an esker aquifer was sampled for natural tracers (stable water isotopes, electrical conductivity and temperature, n = 55) from two depths (30 cm and under the peat layer) in the summer of 2013. The peat levels of the sampling points varied between 0.57 - 1.00 m. In addition, hydraulic conductivity measurements (n = 13) and airborne thermal imaging were carried out and local precipitation was sampled for stable water isotopes. The CRDS-method (Picarro L2120-i analyzer) was applied to analyze δ18O and δ2H values. Local Meteoric Water Line (LMWL) was determined using precipitation from Nuoritta (17 km west from the study site), δ2H = 7.24 δ18O + 7.94 (R2 = 0.996). Ranges for δ18O and δ2H of peatland water were, -13.3 o - -10.3 o and -96.1 o - -75.6 o respectively. Furthermore, electrical conductivity varied between 19.6 - 192.8 mS m-1, hydraulic conductivity between 1.7×10-8 - 5.0×10-4 m s-1 and temperature between 6.1 - 16.8 ° C. Natural tracers were used for identifying water flow patterns of the peatland. Interpretation of the results was complicated due to a stream flowing through the studied peatland. However, groundwater discharge zones were observed alongside the esker and also further away from the esker in the peatland area. This research shows that combination of high-resolution thermal images and discrete field measurements will result in more reliable and precise water flow patterns.

  19. Carbon isotopic composition of deep carbon gases in an ombrogenous peatland, northwestern Ontario, Canada

    SciTech Connect

    Aravena, R. . Center for Groundwater Research and Wetlands Research Center); Warner, B.G. . Wetlands Research Center and Dept. of Geography); Charman, D.J. . Dept. of Geographical Sciences); Belyea, L.R. . School of Biological Sciences); Mathur, S.P. ); Dinel, H. )

    1993-01-01

    Radiocarbon dating and carbon isotope analyses of deep peat and gases in a small ombrogenous peatland in northwestern Ontario reveals the presence of old gases at depth that are 1000-2000 yr younger than the enclosing peat. The authors suggest that the most likely explanation to account for this age discrepancy is the downward movement by advection of younger dissolved organic carbon for use by fermentation a