Preprints
https://doi.org/10.5194/bg-2021-270
https://doi.org/10.5194/bg-2021-270

  20 Oct 2021

20 Oct 2021

Review status: this preprint is currently under review for the journal BG.

Controls on autotrophic and heterotrophic respiration in an ombrotrophic bog

Tracy Rankin, Nigel Roulet, and Tim Moore Tracy Rankin et al.
  • Department of Geography, McGill University, Montreal, H3A 0B9, Canada

Abstract. Northern peatlands are globally significant carbon stores, but the sink strength may vary from year-to-year due to variations in environmental and biogeochemical conditions. This variation is mainly brought about by changes in primary production and ecosystem respiration. The processes that relate to variations in autotrophic respiration (AR; respiration by plant parts) are understood quite well, but heterotrophic respiration (HR; respiration by microbial bacteria in the soil, fungi, etc.) is crudely measured and modelled. This will lead to biased estimates if a change favours one form of respiration over another and alters allocations of carbon to labile pools with different turnover rates. HR has only recently been shown to be more intimately linked to vegetation dynamics than once thought, particularly in wetter, oligotrophic, sedge-dominated ecosystems. The objective of this study is to determine the factors that relate to the spatial and temporal variability in respiration and its autotrophic and heterotrophic components in an ombrotrophic bog (Mer Bleue) where woody shrubs are dominant, and to see if the more dynamic nature of HR in sedges also exists in this bog. Plot level measurements using manual chambers were used to partition respiration from both the dominant shrubs and the sparse sedges at the site, and the controls on respiration were explored by measuring a variety of environmental variables, such as air and soil temperatures (T) and water table (WT) depth. Results show that AR and HR correlate primarily with air and soil T, with WT depth playing an important role in some cases, and that a higher variability in respiration exists for the shrub plots than the sedge plots, especially when WT levels are more variable. Our findings also show that a plant’s response to changes in climate or land-use is related to different mechanisms of obtaining water resources and utilizing symbiotic relationships with other plants around them. These results will improve our understanding of peatland carbon cycling, as well as improve the conceptualization of HR.

Tracy Rankin et al.

Status: open (until 30 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2021-270', Anonymous Referee #1, 15 Nov 2021 reply
    • AC1: 'Reply on RC1', Tracy Rankin, 26 Nov 2021 reply

Tracy Rankin et al.

Tracy Rankin et al.

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Short summary
Respiration is made up of plant and peat sources. How to separate these sources is not well known as peat respiration is influenced by vegetation dynamics, especially in grass-dominated peatlands. Results of plot level measurements from shrubs and sparse grasses in a woody bog show that a plant’s respiration response to changes in climate is related to different mechanisms of obtaining water resources. Hence, respiration is influenced differently than in a grass-dominated peatland.
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