Browsing by Subject "Peatland"

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  • Ojanen, Paavo; Mäkiranta, Päivi; Penttilä, Timo; Minkkinen, Kari (2017)
    Logging residue piles have been suggested to markedly increase the decomposition of the underlying peat soil leading to large carbon dioxide emissions. We aimed at scrutinizing this postulate with straightforward decomposition (mass loss) measurements. For the purpose, authentic soil organic matter (humus and peat) was incubated in mesh bags under piles and at control plots. The effect of piles was assumed to result from physical (shading and insulation on soil surface) and chemical-biological (leaching of nutrients and fresh organic matter) sources. To distinguish between the two, artificial piles of inorganic matter were established to mimic the bare physical effects. Enhancement of decomposition in the soil under the real and artificial piles was assessed by measuring the mass loss of cellulose strips. Logging residue piles had clear physical effects on soil: temperatures were lowered and their diurnal variation subdued, and relative humidity at the soil surface was higher. The effect on soil moisture was also evident, but more variable, including both decreases and increases. These effects, mimicked by the artificial piles, decreased rather than increased cellulose mass loss. As the real piles, on the other hand, increased mass loss, we conclude that logging residue piles may enhance decomposition in soil due to chemical-biological mechanisms. Also the results on humus and peat mass loss indicate that piles can both increase and decrease decomposition. Consistent, remarkable increase in mass loss was not observed. Thus, our results do not support the postulate of logging residue piles dramatically increasing decomposition of soil organic matter. Rather, they hint that the effect of logging residue piles on soil is an interplay of physical and chemical-biological effects and carbon transport via roots and fungi. To fully understand and quantify these effects, vertical C fluxes between piles and soil and horizontal C fluxes within soil need to be assessed in addition to decomposition in soil and piles.
  • Lahtinen, Laura; Mattila, Tuomas; Myllyviita, Tanja; Seppala, Jyri; Vasander, Harri (2022)
    Drained peatlands are a large emission source and a shift to paludiculture (rewetting and cultivation of wettolerant plants) is emerging as a potential emission reduction measure. Paludiculture can potentially results in emission savings from direct emissions, product substitution and carbon storage, but the whole life cycle climate impacts are rarely studied. In this study, we evaluated two paludiculture product systems (cattail (Typha) construction board and common reed (Phragmites) horticultural vermicompost) with cradle-to-grave life cycle assessment (LCA) applied global sensitivity analysis to identify, which parts of the product system would need more research and product development to ensure net emission savings. Based on the results, both product systems result in much lower emissions than current agricultural land use and may be net greenhouse gas sinks (average - 6.0 tCO2eq ha-1 for cattail board; -3.0 tCO2eq ha-1 for reed growing media). The uncertainty in the product life cycle is concentrated to a few key processes: the direct CO2 and CH4 emissions from paludiculture, construction board additives, and CH4 emissions from vermicomposting reed. Further research to these would minimize the uncertainty and help in maximizing the climate mitigation potential of paludiculture derived products.
  • Mannisto, Elisa; Ylanne, Henni; Losoi, Mari; Keinänen, Markku; Yli-Pirilä, Pasi; Korrensalo, Aino; Bäck, Jaana; Hellen, Heidi; Virtanen, Annele; Tuittila, Eeva-Stiina (2023)
    Peatland ecosystems emit biogenic volatile organic compounds (BVOC), which have a net cooling impact on the climate. However, the quality and quantity of BVOC emissions, and how they are regulated by vegetation and peatland type remain poorly understood. Here we measured BVOC emissions with dynamic enclosures from two major boreal peatland types, a minerotrophic fen and an ombrotrophic bog situated in Siikaneva, southern Finland and experimentally assessed the role of vegetation by removing vascular vegetation with or without the moss layer. Our measurements from four campaigns during growing seasons in 2017 and 2018 identified emissions of 59 compounds from nine different chemical groups. Isoprene accounted for 81 % of BVOC emissions. Measurements also revealed uptake of dichloromethane. Total BVOC emissions and the emissions of isoprene, monoterpenoids, sesquiterpenes, homoterpenes, and green leaf volatiles were tightly con-nected to vascular plants. Isoprene and sesquiterpene emissions were associated with sedges, whereas monoterpenoids and homoterpenes were associated with shrubs. Additionally, isoprene and alkane emissions were higher in the fen than in the bog and they significantly contributed to the higher BVOC emissions from intact vegetation in the fen. During an ex-treme drought event in 2018, emissions of organic halides were absent. Our results indicate that climate change with an increase in shrub cover and increased frequency of extreme weather events may have a negative impact on total BVOC emissions that otherwise are predicted to increase in warmer temperatures. However, these changes also accompanied a change in BVOC emission quality. As different compounds differ in their capacity to form secondary organic aerosols, the ultimate climate impact of peatland BVOC emissions may be altered.
  • Kiheri, Heikki; Velmala, Sannakajsa; Pennanen, Taina; Timonen, Sari; Sietiö, Outi-Maaria; Fritze, Hannu; Heinonsalo, Jussi; van Dijk, Netty; Dise, Nancy; Larmola, Tuula (2020)
    Northern peatlands are often dominated by ericaceous shrub species which rely on ericoid mycorrhizal fungi (ERM) for access to organic sources of nutrients, such as nitrogen (N) and phosphorus (P), and host abundant dark septate endophytes (DSE). Relationships between hosts and fungal symbionts may change during deposition of anthropogenic N and P. We studied the long-term effects of N and P addition on two ericaceous shrubs, Calluna vulgaris and Erica tetralix, at Whim Bog, Scotland by analyzing fungal colonization of roots, enzymatic activity, and fungal species composition. Unexpectedly, the frequency of typical ERM intracellular colonization did not change while the occurrence of ERM hyphae tended to increase and DSE hyphae to decrease. Our findings indicate that altered nutrient limitations shift root associated fungal colonization patterns as well as affecting ericaceous root enzyme activity and thereby decomposition potential. Reduction of recalcitrant fungal biomass in melanized DSE may have implications for peatland C sequestration under nutrient addition.
  • Laine, A. M.; Mehtätalo, L.; Tolvanen, A.; Frolking, S.; Tuittila, E-S (2019)
    Northern wetlands with organic soil i.e., mires are significant carbon storages. This key ecosystem service may be threatened by anthropogenic activities and climate change, yet we still lack a consensus on how these major changes affects their carbon sink capacities. We studied how forestry drainage and restoration combined with experimental warming, impacts greenhouse gas fluxes of wetlands with peat. We measured CO2 and CH4 during two and N2O fluxes during one growing season using the chamber method. Gas fluxes were primarily controlled by water table, leaf area and temperature. Land use had a clear impact of on CO2 exchange. Forestry drainage increased respiration rates and decreased field layer net ecosystem CO2 uptake (NEE) and leaf area index (LAI), while at restoration sites the flux rates and LAI had recovered to the level of undrained sites. CH4 emissions were exceptionally low at all sites during our study years due to natural drought, but still somewhat lower at drained compared to undrained sites. Moderate warming triggered an increase in LAI across all land use types. This was accompanied by an increase in cumulative seasonal NEE. Restoration appeared to be an effective tool to return the ecosystem functions of these wetlands as we found no differences in LAI or any gas flux components (PMAX, Reco, NEE, CH4 or N2O) between restored and undrained sites. We did not find any signs that moderate warming would compromise the return of the ecosystem functions related to C sequestration. (C) 2018 Elsevier B.V. All rights reserved.
  • Naafs, B. D. A.; Inglis, G. N.; Zheng, Y.; Amesbury, M. J.; Biester, H.; Bindler, R.; Blewett, J.; Burrows, M. A.; del Castillo Torres, D.; Chambers, F. M.; Cohen, A. D.; Evershed, R. P.; Feakins, S. J.; Galka, M.; Gallego-Sala, A.; Gandois, L.; Gray, D. M.; Hatcher, P. G.; Honorio Coronado, E. N.; Hughes, P. D. M.; Huguet, A.; Kononen, M.; Laggoun-Defarge, F.; Lahteenoja, O.; Lamentowicz, M.; Marchant, R.; McClymont, E.; Pontevedra-Pombal, X.; Ponton, C.; Pourmand, A.; Rizzuti, A. M.; Rochefort, L.; Schellekens, J.; De Vleeschouwer, F.; Pancost, R. D. (2017)
    Glycerol dialkyl glycerol tetraethers (GDGTs) are membrane-spanning lipids from Bacteria and Archaea that are ubiquitous in a range of natural archives and especially abundant in peat. Previous work demonstrated that the distribution of bacterial branched GDGTs (brGDGTs) in mineral soils is correlated to environmental factors such as mean annual air temperature (MAAT) and soil pH. However, the influence of these parameters on brGDGT distributions in peat is largely unknown. Here we investigate the distribution of brGDGTs in 470 samples from 96 peatlands around the world with a broad mean annual air temperature (-8 to 27 degrees C) and pH (3-8) range and present the first peat-specific brGDGT-based temperature and pH calibrations. Our results demonstrate that the degree of cyclisation of brGDGTs in peat is positively correlated with pH, pH = 2.49 x CBTpeat + 8.07 (n = 51, R-2 = 0.58, RMSE = 0.8) and the degree of methylation of brGDGTs is positively correlated with MAAT, MAAT(peat) (degrees C) = 52.18 x MBT'(5me) - 23.05 (n = 96, R-2 = 0.76, RMSE = 4.7 degrees C). These peat-specific calibrations are distinct from the available mineral soil calibrations. In light of the error in the temperature calibration (similar to 4.7 degrees C), we urge caution in any application to reconstruct late Holocene climate variability, where the climatic signals are relatively small, and the duration of excursions could be brief. Instead, these proxies are well-suited to reconstruct large amplitude, longer-term shifts in climate such as deglacial transitions. Indeed, when applied to a peat deposit spanning the late glacial period (similar to 15.2 kyr), we demonstrate that MAAT(peat) yields absolute temperatures and relative temperature changes that are consistent with those from other proxies. In addition, the application of MAAT(peat) to fossil peat (i.e. lignites) has the potential to reconstruct terrestrial climate during the Cenozoic. We conclude that there is clear potential to use brGDGTs in peats and lignites to reconstruct past terrestrial climate. (C) 2017 The Authors. Published by Elsevier Ltd.
  • Chapman, Jack (Helsingin yliopisto, 2022)
    Climate change is expected to cause long-term drying on northern peatlands due to increased evapotranspiration. Summer heatwaves and droughts are also predicted to increase with climate change. Vascular plant leaf area phenology on peatlands is affected by reduced water levels and interannual variation in weather. Nutrient rich mire types are more susceptible to both functional and compositional changes in response to long-term and short-term changes in water level. What remains unexplored is the potential for interactive effects between long-term drying and short-term drought events on leaf area phenology on varying mire types. This study quantifies the response of leaf area phenology to 20-year experimental water level drawdown (WLD) across three mire types of varying nutrient levels (mesotrophic fen, oligotrophic fen and ombrotrophic bog). Measurements were conducted in two contrasting growing seasons, 2017 a cool wet year and 2021 a hot dry year. WLD led to significantly earlier growth peaks across all sites. Community compositional changes in response to WLD were most significant at the more nutrient rich mire sites. At the mesotrophic site WLD resulted in significant reductions in peak leaf area (LAIMAX), which was not observed at the other sites. Across all the WLD plots the hot dry year 2021 resulted in significantly greater LAIMAX relative to the cool wet year 2017, this difference was not significant at any of the control plots. This suggests long-term drying alters the way mire phenology responds to short-term variations in weather. This has important implications for the ability of northern mires to function ‘normally’ under future climate conditions.
  • Płóciennik, Mateusz; Jakiel, Aleksandra; Forysiak, Jacek; Kittel, Piotr; Płaza, Dominik K.; Okupny, Daniel; Pawłowski, Dominik; Obremska, Milena; Brooks, Stephen J.; Kotrys, Bartosz; Luoto, Tomi P. (2021)
    Fens have been forming in the river valleys of central Poland since the Bølling and went through a transformation from fully aquatic to semiterrestrial habitats during the Younger Dryas/Holocene transition. This drove plant and invertebrate communities and left a distinct pattern in chemical sediment composition, which is why river valley peatlands are sensitive palaeo-archives of climatic, hydrological and edaphic changes. Here we reconstruct the Late Weichselian history of the Bęczkowice fen in the upper Luciąża River valley using geochemical, pollen, Cladocera and Chironomidae proxies. Pollen-based age estimation indicates that the analysed peat sequence dates from the Bølling to Early Holocene. The layers 190-170 cm and 125-105 cm of the studied core were reworked by fluvial processes. Chironomidae and Cladocera communities indicate mostly limnetic conditions during the Allerød and early Younger Dryas. Peatland pools were supplied mostly by Luciąża River floods, but also by groundwater. Since the onset of the Holocene, the water level has dropped, eliminating aquatic midges and water fleas, and supporting taxa typical of astatic waters and wet soil.
  • Kakaei Lafdani, Elham; Laurén, Ari; Cvetkovic, Jovana; Pumpanen, Jukka; Saarela, Taija; Palviainen, Marjo (2021)
    Forest regeneration operations increase the concentration of nitrogen (N) in watercourses especially outside the growing season when traditional biological water protection methods are inefficient. Biochar adsorption-based water treatment could be a solution for nutrient retention. We studied the total nitrogen (TN) and nitrate-nitrogen (NO3--N) adsorption-desorption properties of spruce and birch biochar. The adsorption test was performed under four different initial concentrations of TN (1, 2, 3, and 4 mg L-1) using forest runoff water collected from ditch drains of boreal harvested peatland. The results showed that the TN adsorption amount increased linearly from the lowest to the highest concentration. The maximum adsorption capacity was 2.4 and 3.2 times greater in the highest concentration (4 mg L-1) compared to the lowest concentration (1 mg L-1) in spruce and birch biochar, respectively. The NO3--N adsorption amount of birch biochar increased linearly from 0 to 0.15 mg NO3--N g biochar(-1) when the initial concentration of NO3--N increased from 0.2 to 1.4 mg L-1. However, in spruce biochar, the initial concentration did not affect NO3--N adsorption amount. The results indicate that concentration significantly affects the biochar's capacity to adsorb N from water. The desorption test was performed by adding biochar extracted from the adsorption test into the forest runoff water with low TN concentration (0.2 or 0.35 mg L-1). The desorption results showed that desorption was negligibly small, and it was dependent on the TN concentration for birch biochar. Therefore, biochar can be a complementary method supporting water purification in peatland areas.
  • Amesbury, Matthew J.; Booth, Robert K.; Roland, Thomas P.; Bunbury, Joan; Clifford, Michael J.; Charman, Dan J.; Elliot, Suzanne; Finkelstein, Sarah; Garneau, Michelle; Hughes, Paul D. M.; Lamarre, Alexandre; Loisel, Julie; Mackay, Helen; Magnan, Gabriel; Markel, Erin R.; Mitchell, Edward A. D.; Payne, Richard J.; Pelletier, Nicolas; Roe, Helen; Sullivan, Maura E.; Swindles, Graeme T.; Talbot, Julie; van Bellen, Simon; Warner, Barry G. (2018)
    Fossil testate amoeba assemblages have been used to reconstruct peatland palaeohydrology for more than two decades. While transfer function training sets are typically of local-to regional-scale in extent, combining those data to cover broad ecohydrological gradients, from the regional-to continental- and hemispheric-scales, is useful to assess if ecological optima of species vary geographically and therefore may have also varied over time. Continental-scale transfer functions can also maximise modern analogue quality without losing reconstructive skill, providing the opportunity to contextualise understanding of purely statistical outputs with greater insight into the biogeography of organisms. Here, we compiled, at moderate taxonomic resolution, a dataset of nearly 2000 modern surface peatland testate amoeba samples from 137 peatlands throughout North America. We developed transfer functions using four model types, tested them statistically and applied them to independent palaeoenvironmental data. By subdividing the dataset into eco-regions, we examined biogeographical patterns of hydrological optima and species distribution across North America. We combined our new dataset with data from Europe to create a combined transfer function. The performance of our North-American transfer function was equivalent to published models and reconstructions were comparable to those developed using regional training sets. The new model can therefore be used as an effective tool to reconstruct peatland palaeohydrology throughout the North American continent. Some eco-regions exhibited lower taxonomic diversity and some key indicator taxa had restricted ranges. However, these patterns occurred against a background of general cosmopolitanism, at the moderate taxonomic resolution used. Likely biogeographical patterns at higher taxonomic resolution therefore do not affect transfer function performance. Output from the combined North American and European model suggested that any geographical limit of scale beyond which further compilation of peatland testate amoeba data would not be valid has not yet been reached, therefore advocating the potential for a Holarctic synthesis of peatland testate amoeba data. Extending data synthesis to the tropics and the Southern Hemisphere would be more challenging due to higher regional endemism in those areas. (C) 2018 The Authors. Published by Elsevier Ltd.