EGU2020-9182
https://doi.org/10.5194/egusphere-egu2020-9182
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Soil organic carbon along a geothermal gradient in North-West Canada

Tino Peplau1, Edward Gregorich2, and Christopher Poeplau1
Tino Peplau et al.
  • 1Thünen Institute of Climate-Smart Agriculture, Braunschweig, Germany (tino.peplau@thuenen.de)
  • 2Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON K1A 0C6, Canada

Global warming will increase soil microbial activity and thus catalyse the mineralisation of soil organic carbon (SOC). Predicting the dynamics of soil organic carbon in response to warming is crucial but associated with large uncertainties, owing to experimental limitations. Most studies use in-vitro incubation experiments or relatively short-term in-situ soil warming experiments. Long-term observations on the consequences of soil warming on whole-profile SOC are still rare. Here, we used a long-term geothermal gradient in North-West Canada to study effects of warming on quantity and quality of SOC in an aspen forest ecosystem.

The Takhini hot springs are located within the region of discontinuous permafrost in the southern Yukon Territory, Canada. The springs warm the surrounding soil constantly and lead to a horizontal temperature gradient of approximately 10°C within a radius of 100 meters. As these natural springs heat the ground for centuries and the forest ecosystem surrounding the springs is relatively homogenous, the site provides ideal conditions for observing long-term effects of soil warming on ecosystem properties. Soils were sampled at four different warming intensities to a depth of 80 cm and analysed for their SOC content and further soil properties in different depths. 

For the bulk soil, we found a significant negative relationship between soil temperature and SOC stocks. This confirms that climate change will most likely induce SOC loss and thus a positive climate- carbon cycle feedback loop. The response of five different SOC fractions to warming will also be presented.

How to cite: Peplau, T., Gregorich, E., and Poeplau, C.: Soil organic carbon along a geothermal gradient in North-West Canada, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9182, https://doi.org/10.5194/egusphere-egu2020-9182, 2020

How to cite: Peplau, T., Gregorich, E., and Poeplau, C.: Soil organic carbon along a geothermal gradient in North-West Canada, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9182, https://doi.org/10.5194/egusphere-egu2020-9182, 2020

Comments on the presentation

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Presentation version 1 – uploaded on 29 Apr 2020
  • CC2: Which fraction responded most to warming?, Yunyun Zheng, 05 May 2020

    Hi Peplau,

    Just wondering which fraction did you find respond most to warming? 

    • AC1: Reply to CC2, Tino Peplau, 05 May 2020

      Hello Yunyun Zheng,

      considering the current avaiable data, the POM fraction (particulate organic matter) showed the strongest reaction.

  • CC3: Comment on EGU2020-9182, Felipe Aburto, 05 May 2020

    Hello Tino

    Just wondering if you know how ecosystem productivity changes along the thermal gradient?

    • AC2: Reply to CC3, Tino Peplau, 06 May 2020

      Hello Felipe,

      this is a good question which will be part of our next field campaign. The transect is not vey long, so the productivity should change only in a small scale, as the generall pattern of the vegetation stays more or less the same. I expect a higher productivity in the warmer area but so far I don't have a proof for that.

      • CC4: Reply to AC2, Felipe Aburto, 07 May 2020

        That will be a great addition to your dataset! Good luck on your new field campaign!