Seasonality, drivers, and isotopic composition of soil CO 2 fluxes from tropical forests of the Congo Basin

Biogeosciences Discussions

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Baumgartner, Simon¹  Van Oost, Kristof²  Boeckx, Pascal³  Doetterl, Sebastian¹  Werner, Roland Anton¹  Six, Johan¹  Barthel, Matti¹  Drake, Travis William¹  Bauters, Marijn³  Makelele, Isaac Ahanamungu³  Mugula, John Kalume⁵  Summerauer, Laura¹  Gallarotti, Nora¹  Cizungu Ntaboba, Landry⁶ 

[1] Department of Environmental Systems Science, Swiss Federal Institute of Technology;Earth and Life Institute, Université Catholique de Louvain;Department of Green Chemistry and Technology, Ghent University;Department of Environment, Ghent University;Département de Biologie, Université Officielle de Bukavu;Département d'Agronomie, Université Catholique de Bukavu

DOI  :  10.5194/bg-17-6207-2020

学科分类：生物科学（综合）

来源: Copernicus Publications

【 摘 要 】

Soil respiration is an important carbon flux and key process determining the net ecosystem production of terrestrial ecosystems. To address the lack of quantification and understanding of seasonality in soil respiration of tropical forests in the Congo Basin, soil CO 2 fluxes and potential controlling factors were measured annually in two dominant forest types (lowland and montane) of the Congo Basin over 2 years at varying temporal resolution. Soil CO 2 fluxes from the Congo Basin resulted in 3.45  ±  1.14 and 3.13  ±  1.22  µ mol CO 2  m −2  s −1 for lowland and montane forests, respectively. Soil CO 2 fluxes in montane forest soils showed a clear seasonality with decreasing flux rates during the dry season. Montane forest soil CO 2 fluxes were positively correlated with soil moisture, while CO 2 fluxes in the lowland forest were not. Smaller differences of δ 13 C values of leaf litter, soil organic carbon (SOC), and soil CO 2 indicated that SOC in lowland forests is more decomposed than in montane forests, suggesting that respiration is controlled by C availability rather than environmental factors. In general, C in montane forests was more enriched in 13 C throughout the whole cascade of carbon intake via photosynthesis, litterfall, SOC, and soil CO 2 compared to lowland forests, pointing to a more open system. Even though soil CO 2 fluxes are similarly high in lowland and montane forests of the Congo Basin, the drivers of them seem to be different, i.e., soil moisture for montane forest and C availability for lowland forest.

【 授权许可】

CC BY