Effects of water table level and nitrogen deposition on methane and nitrous oxide emissions in an alpine peatland
<p>Alpine peatlands are recognized as a major natural contributor to the budgets of atmospheric methane (<span class="inline-formula">CH<sub>4</sub></span>) but as a weak nitrous oxide (<span class="inline-formula">N<sub>2</sub>O<...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-11-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/19/5187/2022/bg-19-5187-2022.pdf |
| Summary: | <p>Alpine peatlands are recognized as a major natural contributor to the
budgets of atmospheric methane (<span class="inline-formula">CH<sub>4</sub></span>) but as a weak nitrous oxide
(<span class="inline-formula">N<sub>2</sub>O</span>) source. Anthropogenic activities and climate change have put
these fragile nitrogen (N)-limited peatlands under pressure by altering
water table (WT) levels and enhancing N deposition. The response of
greenhouse gas (GHG) emissions from these peatlands to these changes is
uncertain. To address this knowledge gap, we conducted a mesocosm experiment
in 2018 and 2019 investigating individual and interactive effects of three
WT levels (WT<span class="inline-formula"><sub>−30</sub></span>, 30 cm below soil surface; WT<span class="inline-formula"><sub>0</sub></span>, 0 cm at the soil
surface; WT<span class="inline-formula"><sub>10</sub></span>, 10 cm above soil surface) and multiple levels of N
deposition (0, 20, 40, 80 and 160 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">kg</mi><mspace width="0.125em" linebreak="nobreak"/><mi mathvariant="normal">N</mi><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">ha</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">yr</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="68pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="af9da8ae6aa9e86f67fe417505ec1787"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-5187-2022-ie00001.svg" width="68pt" height="15pt" src="bg-19-5187-2022-ie00001.png"/></svg:svg></span></span>) on growing
season <span class="inline-formula">CH<sub>4</sub></span> and <span class="inline-formula">N<sub>2</sub>O</span> emissions in the Zoige alpine peatland,
Qinghai–Tibetan Plateau. We found that the elevated WT levels increased
<span class="inline-formula">CH<sub>4</sub></span> emissions, while N deposition had nonlinear effects (with
stimulation at moderate levels but inhibition at higher levels). In
contrast no clear pattern of the effect of WT levels on the cumulative
<span class="inline-formula">N<sub>2</sub>O</span> emissions was evident, while N deposition led to a consistent and
linear increase (emission factor: 2.3 %–2.8 %), and this was dependent
on the WT levels. Given the current N deposition in the Zoige alpine
peatland (1.08–17.81 <span class="inline-formula">kg N ha<sup>−1</sup></span>), our results suggested that
the <span class="inline-formula">CH<sub>4</sub></span> and <span class="inline-formula">N<sub>2</sub>O</span> emissions from the alpine peatlands could greatly
increase in response to the possible doubling N deposition in the future. We
believe that our results provide insights into how interactions between
climate change and human disturbance will alter <span class="inline-formula">CH<sub>4</sub></span> and <span class="inline-formula">N<sub>2</sub>O</span>
emissions from this globally important habitat.</p> |
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| ISSN: | 1726-4170 1726-4189 |