Aquatic and soil CO<sub>2</sub> emissions from forested wetlands of Congo's Cuvette Centrale
<p>Within tropical forest ecosystems, wetlands such as swamp forests are an important interface between the terrestrial and aquatic landscape. Despite this assumed importance, there is a paucity of carbon flux data from wetlands in tropical Africa. Therefore, the magnitude and source of carbon...
Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-06-01
|
| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/22/3011/2025/bg-22-3011-2025.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | <p>Within tropical forest ecosystems, wetlands such as swamp forests are an important interface between the terrestrial and aquatic landscape. Despite this assumed importance, there is a paucity of carbon flux data from wetlands in tropical Africa. Therefore, the magnitude and source of carbon dioxide (CO<span class="inline-formula"><sub>2</sub></span>) fluxes, carbon isotopic ratios, and environmental conditions were measured for 3 years between 2019 and 2022 in a seasonally flooded forest and a perennially flooded forest in the Cuvette Centrale of the Congo Basin. The mean surface fluxes for the seasonally flooded site and the perennially flooded site were <span class="inline-formula">2.36±0.51</span> and <span class="inline-formula">4.38±0.64</span> <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">µ</mi><mi mathvariant="normal">mol</mi><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">s</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="64pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="0b8c9b3f35e4050769cdae1560e696a7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-3011-2025-ie00001.svg" width="64pt" height="15pt" src="bg-22-3011-2025-ie00001.png"/></svg:svg></span></span>, respectively. The time series data revealed no marked seasonal pattern in CO<span class="inline-formula"><sub>2</sub></span> fluxes. As for the environmental drivers, the fluxes at the seasonally flooded site exhibited a positive correlation with soil temperature and soil moisture. Additionally, the water level appeared to be a significant factor, demonstrating a quadratic relationship with the soil fluxes at the seasonally flooded site. <span class="inline-formula"><i>δ</i><sup>13</sup></span>C values showed a progressive increase across the carbon pools, from aboveground biomass to leaf litter and then to soil organic carbon (SOC). However, there was no significant difference in <span class="inline-formula"><i>δ</i><sup>13</sup></span>C enrichment between SOC and soil-respired CO<span class="inline-formula"><sub>2</sub></span>. This lack of enrichment can be attributed to either a significant contribution from the autotrophic component of soil respiration or closed system dynamics.</p>
<p>An in-situ-derived gas transfer velocity (<span class="inline-formula"><i>k</i><sub>600</sub>=2.95</span> cm h<span class="inline-formula"><sup>−1</sup></span>) was used to calculate the aquatic CO<span class="inline-formula"><sub>2</sub></span> fluxes at the perennially flooded site. Despite the low <span class="inline-formula"><i>k</i><sub>600</sub></span>, relatively high CO<span class="inline-formula"><sub>2</sub></span> surface fluxes were found due to very high partial pressure of CO<span class="inline-formula"><sub>2</sub></span> (pCO<span class="inline-formula"><sub>2</sub></span>) values measured in the flooding waters. Overall, these results offer a quantification of the CO<span class="inline-formula"><sub>2</sub></span> fluxes from forested wetlands and provide insights into the temporal variability of these fluxes and their sensitivity to environmental drivers.</p> |
|---|---|
| ISSN: | 1726-4170 1726-4189 |