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Ecosystem respiration in a heterogeneous temperate peatland and its sensitivity to peat temperature and water table depth

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    0380461 - ÚVGZ 2014 RIV NL eng J - Journal Article
    Juszczak, R. - Humphreys, E. - Acosta, Manuel - Michalak-Galczewska, M. - Kayzer, D. - Olejnik, Janusz
    Ecosystem respiration in a heterogeneous temperate peatland and its sensitivity to peat temperature and water table depth.
    Plant and Soil. Roč. 366, 1-2 (2013), s. 505-520. ISSN 0032-079X
    Institutional support: RVO:67179843
    Keywords : Ecosystem respiration * Geogenous peatland * Chamber measurements * CO2 fluxes * Water table depth
    Subject RIV: EH - Ecology, Behaviour
    Impact factor: 3.235, year: 2013

    Background and aims Ecosystem respiration (R eco ) is controlled by thermal and hydrologic regimes, but their relative importance in defining the CO2 emissions in peatlands seems to be site specific. The aim of the paper is to investigate the sensitivity of R eco to variations in temperature and water table depth (WTD) in a wet, geogenous temperate peatland. Methods The CO2 fluxes were measured using chambers. Measurements were made at four microsites with different vegetation communities every 3 to 4 weeks during the period 2008–2009, 2 years with contrasting WTD patterns. Models were used to examine the relative response of each microsite to variations in peat temperature and WTD and used to estimate annual total Reco. Results Temporal variations in Reco were strongly related to peat temperature at the 5 cm depth. However, two of the microsites did not show any significant change in this relationship while two others showed contrasting responses including an increase and decrease in temperature sensitivity with deeper WTD. A combined temperature and WTD model explained up to 94 % of the temporal variation in daily average Reco and was used to show that on an annual basis, Reco was between 5 and 18 % greater in the warmer year with deeper WTD. Conclusion Reco may have remained insensitive to WTD variations at one microsite due to the dominance of autotrophic respiration from abundant sedge biomass. At a Sphagnum-dominated microsite, a lack of response may have been due to relatively small variations in WTD that did not greatly influence microbial respiration or due to offsets between decreasing and increasing respiration rates in near-surface and deeper peat. The microsite with the most recalcitrant peat had reduced Reco sensitivity to temperature under more aerobic conditions while another microsite showed the opposite response, perhaps due to less nutrient availability during the wet year.
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