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Variation in CO2 and CH4 Fluxes Among Land Cover Types in Heterogeneous Arctic Tundra in Northeastern Siberia.
- Source :
- Biogeosciences Discussions; 1/26/2022, p1-35, 35p
- Publication Year :
- 2022
-
Abstract
- Arctic tundra is facing unprecedented warming, resulting in shifts in the vegetation, thaw regimes, and potentially in the ecosystem-atmosphere exchange of carbon (C). The estimates of regional carbon dioxide (CO<subscript>2</subscript>) and methane (CH<subscript>4</subscript>) budgets, however, are highly uncertain. We measured CO<subscript>2</subscript> and CH<subscript>4</subscript> fluxes, vegetation composition and leaf area index (LAI), thaw depth, and soil wetness in Tiksi (71° N, 128° E), a heterogeneous site located within the prostrate dwarf-shrub tundra zone in northeastern Siberia. Using the closed chamber method, we determined net ecosystem exchange (NEE) of CO<subscript>2</subscript>, dark ecosystem respiration (ER), ecosystem gross photosynthesis (Pg), and CH<subscript>4</subscript> fluxes during the growing season. We applied a previously developed high-spatial-resolution land-cover map over an m area of 35.8 km². Among the land-cover types varying from barrens to dwarf-shrub tundra and tundra wetlands, the light-saturated NEE and Pg scaled with the LAI of vascular plants. Thus, the graminoid-dominated tundra wetlands, with high LAI and the deepest thaw depth, had the highest light-saturated NEE and Pg (up to -21 (uptake) and 28 mmol m<superscript>-2</superscript> h<superscript>-1</superscript>, respectively) and were disproportionately important for the summertime CO<subscript>2</subscript> sequestration on a landscape scale. Dry tundra, including the dwarf-shrub-dominated vegetation and only sparsely vegetated lichen tundra, had only small CO<subscript>2</subscript> exchange rates. While tundra wetlands were sources of CH<subscript>4</subscript>, lichen tundra, including bare ground habitats, consumed atmospheric CH<subscript>4</subscript> at a substantial rate. On a landscape scale, the consumption by lichen tundra and barrens could offset ca. 10% of the CH<subscript>4</subscript> emissions. We acknowledge the uncertainty involved in spatial extrapolations due to a small number of replicates per land-cover type. This study, however, highlights the need for distinguishing different land-cover types including the dry tundra habitats to account for their consumption of the atmospheric CH<subscript>4</subscript> when estimating tundra C-exchange on a larger spatial scale. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 18106277
- Database :
- Complementary Index
- Journal :
- Biogeosciences Discussions
- Publication Type :
- Academic Journal
- Accession number :
- 154914717
- Full Text :
- https://doi.org/10.5194/bg-2022-5