Fire pattern in a drainage-affected boreal bog

Fire is an important natural disturbance element in the boreal zone, not only in the forested areas but also wetter peatland ecosystems. Predicted climate warming is expected to cause a moderate water-level drawdown in northern peatlands, which might result in increased frequency and severity of fires in boreal peatlands because of increase in fire-loading. We surveyed the fire pattern and the impact of drainage to the fire pattern on partly drained and pristine parts of a boreal raised bog using three sampling transects reaching from drainage-affected area to a pristine, fire-impacted bog area. We detected that dry bog hummock surfaces provided spreading routes for fire while hollow surfaces stayed almost intact. Drainage had promoted succession that lead to dominance of hummock vegetation. The lowered water level and abundance of hummock surfaces typical to the drainage-affected area was favourable for fire. The results suggest an increase in fire impact following drainage and that under changing climate bogs may become more vulnerable for fire.Peer reviewe

Literature review on testate amoebae as environmental indicators and as a functional part of the microbial community in northern peatlands

Funding Information: This work is supported by the Academy of Finland (project codes: 337549, 330840). We thank David Wilson for polishing the English, Kimmo Tolonen for help in finding old publications and Edward Mitchell for his valuable advice on testate amoeba nomenclature. Publisher Copyright: © 2022, IMCG and IPS. All rights reserved.In this review we assess past and current trends in the use of testate amoebae in peatland science, concentrating mainly on studies conducted in northern peatlands. We also discuss the potential of testate amoebae for future research. Testate amoebae are unicellular protists that are covered by protective tests which are easily identifiable and are stored in peat over millennia. Testate amoeba species are specialised to live in a thin water film coating the mosses that creates different microhabitats for species varying in size and shape. They are therefore considered good indicators for hydrology, in particular. In peatlands they represent dominant consumers in the microbial food web, but mixotrophic species also contribute to photosynthesis. Due to their functional role in peatland microbial communities, and as related to challenges in identification and taxonomy, there has been increasing interest towards understanding their functional traits. We suggest that more fundamental research about testate amoeba taxonomy, autecology and functional ecology is needed, but at the same time we can conclude that testate amoebae are a useful tool for contemporary topics in peatland science, including climate-induced changes in peatland functioning and peatland restoration.Peer reviewe

Are high CH4 emissions from restored Central European peatlands due to earlier methanogen transplantation through manure?

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Vegetation structure and photosynthesis respond rapidly to restoration in young coastal fens

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Effect of water table drawdown on northern peatland methane dynamics: Implications for climate change

This is the peer reviewed version of the following article: Strack, M., Waddington, J.M. and Tuittila, E.-S. 2004. The effect of water table drawdown on northern peatland methane emissions: Implications for climate change. Global Biogeochemical Cycles, 18, GB4003, doi: 10.1029/2003GB002209, which has been published in final form at https://doi.org/10.1029/2003GB002209. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.As natural sources of methane (CH4), peatlands play an important role in the global carbon cycle. Climate models predict that evapotranspiration will increase under a 2 x CO2 scenario due to increased temperatures leading to lowered water tables at many northern latitudes. Given that the position of the water table within a peatland can have a large effect on CH4 emissions, climate change may alter the CH4 emissions from peatlands in this area. Research was conducted during 2001–2003 on natural and drained (8 years prior) sites within a poor fen in central Quebec. Flux measurements were made for each site at different microtopographical features that varied in depth to water table and vegetation cover. The quantity of CH4 dissolved in the pore water was measured in the field and the potential of the peat for CH4 production and consumption was determined in the laboratory. Methane emissions and storage were lower in the drained fen. Growing season CH4 emissions at the drained site were 55% lower than the control site, primarily due to significantly reduced fluxes from topographic highs (up to 97% reduction), while the flux from topographically low areas remained high. The maintenance of high fluxes at these hollow sites was related to hydrological and ecological effects of the water table drawdown. The removal of standing water removed a potential zone of CH4 oxidation. It also enabled plant colonization at these locations, leading to an increase in gross ecosystem photosynthesis (GEP). At the hollow sites, seasonal CH4 emissions were significantly correlated to seasonal GEP (R2 = 0.85). These results suggest that the response of northern peatland CH4 dynamics to climate change depends on the antecedent moisture conditions of the site. Moreover, ecological succession can play an important role for determining future CH4 emissions, particularly from wetter sites

Inter-seasonal investigation of coupled C & N greenhouse gas fluxes in pristine northern ecosystems

Accurate annual greenhouse gas (GHG) budgets are the crucial baseline for global climate change forecast scenarios. On the other hand, the parameterization of these forecast models requires more than high-quality GHG datasets, but also the constant improvement of the representation of GHG producing and consuming processes. Extensive research efforts are therefore focusing on increasing our knowledge of the main GHG producing carbon (C) and nitrogen (N) cycles, though surprisingly not so much into their direct interaction. Most annual GHG budgets from pristine northern ecosystems are based on interpolated datasets from sampling campaigns mainly taken during the growing season. Within the ERC funded FluxWIN project, we are investigating how soil and pore water C & N interact and their biogeochemical GHG drivers change over seasons. Freeze-thaw events have previously been identified as significant GHG drivers by rapidly changing moisture and oxygen conditions in the soil matrix, but it remains unclear if and how C & N coupling contributes to these non-growing season emissions. Therefore, a fully automated static chamber system is monitoring GHG fluxes in high frequency at a boreal peatland ecosystem in Siikaneva, Finland. Nutrient stocks and biogeochemical dynamics within the soil matrix are compared to GHG soil-atmosphere exchange in the form of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) all year-round. We control for climatic variability and isolate differences in non-growing season emissions by using a moisture gradient from well-drained upland soils to adjacent wetland ecosystems. The use of these automated high-frequency GHG measurements in combination with year-round biogeochemical monitoring maximizes the likelihood of capturing episodic emissions and their drivers, which are particularly important during fall freeze and spring thaw periods. The gained information on the coupled C & N biogeochemical cycles will improve feedback estimates of climate change by including non-growing season processes in global-scale process-based models

Interacting effects of vegetation components and water level on methane dynamics in a boreal fen

Vegetation and hydrology are important controlling factors in peatland methane dynamics. This study aimed at investigating the role of vegetation components, sedges, dwarf shrubs, and Sphagnum mosses, in methane fluxes of a boreal fen under natural and experimental water level draw-down conditions. We measured the fluxes during growing seasons 2001-2004 using the static chamber technique in a field experiment where the role of the ecosystem components was assessed via plant removal treatments. The first year was a calibration year after which the water level draw-down and vegetation removal treatments were applied. Under natural water level conditions, plant-mediated fluxes comprised 68%-78% of the mean growing season flux (1:73 +/- 0:17 gCH(4) m(-2) month 1 from June to September), of which Sphagnum mosses and sedges accounted for one-fourth and three-fourths, respectively. The presence of dwarf shrubs, on the other hand, had a slightly attenuating effect on the fluxes. In water level drawdown conditions, the mean flux was close to zero (0:03 +/- 0:03 gCH(4) m(-2) month(-1)) and the presence and absence of the plant groups had a negligible effect. In conclusion, water level acted as a switch; only in natural water level conditions did vegetation regulate the net fluxes. The results are relevant for assessing the response of fen peatland fluxes to changing climatic conditions, as water level drawdown and the consequent vegetation succession are the major projected impacts of climate change on northern peatlands.Peer reviewe