Undervine groundcover substantially increases shallow but not deep soil carbon in a temperate vineyard

This study investigated the role of fire-killed woody debris as a source of soil carbon in black spruce (Picea mariana (Mill.) BSP) stands in Manitoba, Canada. We measured the amount of standing dead and downed woody debris along an upland chronosequence, including wood partially and completely covered by moss growth. Such woody debris is rarely included in measurement protocols and composed up to 26% of the total amount of woody debris in older stands, suggesting that it is important to measure all types of woody debris in ecosystems where burial by organic matter is possible. Based on these data and existing net primary production (NPP) values, we used a mass-balance model to assess the potential impact of fire-killed wood on long-term carbon storage at this site. The amount of carbon stored in deeper soil organic layers, which persists over millennia, was used to represent this long-term carbon. We estimate that between 10% and 60% of the deep-soil carbon is derived from wood biomass. Sensitivity analyses suggest that this estimate is most affected by the fire return interval, decay rate of wood, amount of NPP, and decay rate of the char (postfire) carbon pool. Landscape variations in these terms could account for large differences in deep-soil carbon. The model was less sensitive to fire consumption rates and to rates at which standing dead becomes woody debris. All model runs, however, suggest that woody debris plays an important role in long-term carbon storage for this area.

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Drying-Wetting Cycles: Effect on Deep Soil Carbon

Soil Systems ◽

10.3390/soils2010003 ◽

2018 ◽

Vol 2 (1) ◽

pp. 3 ◽

Cited By ~ 1

Author(s):

Ji Qi ◽

Daniel Markewitz ◽

Maryam Foroughi ◽

Eric Jokela ◽

Brian Strahm ◽

...

Keyword(s):

Soil Carbon ◽

Deep Soil

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Interactive Feedbacks of Climate, Mineralogy and Microbiological Communities on Soil Carbon: A Deep Soil Warming Experiment

10.46427/gold2020.1762 ◽

2020 ◽

Author(s):

Casey McGrath ◽

Susan Crow ◽

Caitlin Hicks Pries ◽

Nhu Nguyen ◽

Brian Glazer ◽

...

Keyword(s):

Soil Carbon ◽

Soil Warming ◽

Deep Soil

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Radiocarbon measurements of ecosystem respiration and soil pore-space CO<sub>2</sub> in Utqiaġvik (Barrow), Alaska

Earth System Science Data ◽

10.5194/essd-10-1943-2018 ◽

2018 ◽

Vol 10 (4) ◽

pp. 1943-1957 ◽

Cited By ~ 6

Author(s):

Lydia J. S. Vaughn ◽

Margaret S. Torn

Keyword(s):

Soil Carbon ◽

Ecosystem Respiration ◽

Pore Space ◽

Co2 Flux ◽

Co2 Production ◽

Data Repository ◽

Deep Soil ◽

Environmental Controls ◽

Soil Pore Space ◽

Pool Model

Abstract. Radiocarbon measurements of ecosystem respiration and soil pore space CO2 are useful for determining the sources of ecosystem respiration, identifying environmental controls on soil carbon cycling rates, and parameterizing and evaluating models of the carbon cycle. We measured flux rates and radiocarbon content of ecosystem respiration, as well as radiocarbon in soil profile CO2 in Utqiaġvik (Barrow), Alaska, during the summers of 2012, 2013, and 2014. We found that radiocarbon in ecosystem respiration (Δ14CReco) ranged from +60.5 to −160 ‰ with a median value of +23.3 ‰. Ecosystem respiration became more depleted in radiocarbon from summer to autumn, indicating increased decomposition of old soil organic carbon and/or decreased CO2 production from fast-cycling carbon pools. Across permafrost features, ecosystem respiration from high-centered polygons was depleted in radiocarbon relative to other polygon types. Radiocarbon content in soil pore-space CO2 varied between −7.1 and −280 ‰, becoming more negative with depth in individual soil profiles. These pore-space radiocarbon values correspond to CO2 mean ages of 410 to 3350 years, based on a steady-state, one-pool model. Together, these data indicate that deep soil respiration was derived primarily from old, slow-cycling carbon, but that total CO2 fluxes depended largely on autotrophic respiration and heterotrophic decomposition of fast-cycling carbon within the shallowest soil layers. The relative contributions of these different CO2 sources were highly variable across microtopographic features and time in the sampling season. The highly negative Δ14C values in soil pore-space CO2 and autumn ecosystem respiration indicate that when it is not frozen, very old soil carbon is vulnerable to decomposition. Radiocarbon data and associated CO2 flux and temperature data are stored in the data repository of the Next Generation Ecosystem Experiments (NGEE-Arctic) at http://dx.doi.org/10.5440/1364062 and https://doi.org/10.5440/1418853.

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