Environmental forcing does not induce diel or synoptic variation in the carbon isotope content of forest soil respiration

Bowling, David R.; Egan, Jocelyn; Hall, Steven J.; Risk, D. A.

doi:10.5194/bg-12-5143-2015

Cited by 39 publications

(42 citation statements)

References 85 publications

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“…Calibration studies of soil carbonate must collect field data at high temporal resolution (e.g., Bowling et al, ; Oerter et al, ; Oerter & Bowen, ) and use several lines of evidence to identify formation times. For example, consider if the present data set did not include high resolution environmental data.…”

Section: Discussionmentioning

confidence: 99%

“…Temperature and soil moisture measurements were taken every 15 min with HOBO loggers at 0–40 cm depth. Soil CO 2 samples were extracted from stainless steel gas wells (two plots of 15–45 cm) and measured every 2 hr using a LI‐COR LI‐820 infrared gas analyzer connected to an automated pump system (similar to Bowling et al, ). Samples were calibrated to a tank of known pCO 2 or, where tank failure disallowed this, to the most recent ambient air CO 2 values.…”

Section: Study Location and Methodologymentioning

confidence: 99%

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Seasonal Bias in Soil Carbonate Formation and Its Implications for Interpreting High‐Resolution Paleoarchives: Evidence From Southern Utah

et al. 2019

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Pedogenic carbonate is commonly used as a paleoarchive, but its interpretation is limited by our understanding of its formation conditions. We investigated laminated soil carbonate rinds as a high‐resolution paleoarchive in Torrey, Utah, USA, by characterizing and modeling their formation conditions. We compared late Holocene (<5 ka) soil carbonate conventional (C and O) and “clumped” isotopes to modern soil environment and isotope measurements: soil CO2 partial pressure, soil temperature, soil moisture, δ13C‐soil CO2, δ18O precipitation, and δ18O‐soil water. Data unambiguously identified a strong summer seasonality bias, but modeling suggested soil carbonate formed several times throughout the year during infiltration events causing dissolution‐formation reactions. This apparent discrepancy resulted from preferential preservation of calcite formed from the largest annual infiltration events (summer) overprinting previously formed calcite. Soil carbonate therefore formed predominantly due to changes in soil water content. As soil CO2 was at its annual maximum during soil carbonate formation, assuming uniformly low soil CO2 formation conditions for soil carbonate in estimating paleoatmospheric CO2 is likely not viable. Additionally, we showed modern summer δ13C‐soil CO2 and soil CO2 measurements could not produce a modeled δ13C‐soil carbonate consistent with late Holocene observations. We suggest using multiple lines of evidence to identify nonanalogous modern conditions. Finally, a nearly linear radiocarbon age model from a laminated rind showed that rinds can be used as a high‐resolution paleoarchive if samples are from a single depth and the timing and conditions of soil carbonate formation can be constrained through time.

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Section: Discussionmentioning

confidence: 99%

Section: Study Location and Methodologymentioning

confidence: 99%

Seasonal Bias in Soil Carbonate Formation and Its Implications for Interpreting High‐Resolution Paleoarchives: Evidence From Southern Utah

et al. 2019

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“…We have recently published a comparison of an automated version of this method with direct measurement of δ 13 C of CO 2 in the soil surface flux with automated chambers (Bowling et al . ). In that study the automated gas well sampling involved considerably more sampled volume (>2 L) without problem at 10 and 30 cm.…”

Section: Methodsmentioning

confidence: 97%

Carbon isotopic composition of forest soil respiration in the decade following bark beetle and stem girdling disturbances in the Rocky Mountains

Chan

Trahan

Moore

et al. 2016

Plant Cell & Environment

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Bark beetle outbreaks are widespread in western North American forests, reducing primary productivity and transpiration, leading to forest mortality across large areas and altering ecosystem carbon cycling. Here the carbon isotope composition (δ 13 C) of soil respiration (δ J ) was monitored in the decade after disturbance for forests affected naturally by mountain pine beetle infestation and artificially by stem girdling. The seasonal mean δ J changed along both chronosequences. We found (a) enrichment of δ J relative to controls (<1 ‰) in near-surface soils in the first 2 years after disturbance; (b) depletion (1‰ or no change) during years 3-7; and (c) a second period of enrichment (1-2‰) in years 8-10. Results were consistent with isotopic patterns associated with the gradual death and decomposition of rhizosphere organisms, fine roots, conifer needles and woody roots and debris over the course of a decade after mortality. Finally, δ J was progressively more 13 C-depleted deeper in the soil than near the surface, while the bulk soil followed the well-established pattern of 13 C-enrichment at depth. Overall, differences in δ J between mortality classes (<1‰) and soil depths (<3‰) were smaller than variability within a class or depth over a season (up to 6‰).

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“…We did not collect location‐specific C a or δ a , and thus, we assumed that both values were homogenous across the study site. Previous studies have demonstrated that the variability of C a or δ a is negligible compared to the much larger variability of these quantities in the soil [ Riveros‐Iregui et al ., ; Bowling et al ., ; Mauer et al , ]. We then calculated the intercept of the regression ( δ R ) as shown in Figure .…”

Section: Methodsmentioning

confidence: 99%

Spatial and seasonal variabilities of the stable carbon isotope composition of soil CO₂ concentration and flux in complex terrain

2016

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Biogeochemical processes driving the spatial variability of soil CO2 production and flux are well studied, but little is known about the variability in the spatial distribution of the stable carbon isotopes that make up soil CO2, particularly in complex terrain. Spatial differences in stable isotopes of soil CO2 could indicate fundamental differences in isotopic fractionation at the landscape level and may be useful to inform modeling of carbon cycling over large areas. We measured the spatial and seasonal variabilities of the δ13C of soil CO2 (δS) and the δ13C of soil CO2 flux (δP) in a subalpine forest ecosystem located in the Rocky Mountains of Montana. We found consistently more isotopically depleted values of δS and δP in low and wet areas of the landscape relative to steep and dry areas. Our results suggest that the spatial patterns of δS and δP are strongly mediated by soil water and soil respiration rate. More interestingly, our analysis revealed different temporal trends in δP across the landscape; in high landscape positions δP became more positive, whereas in low landscape positions δP became more negative with time. These trends might be the result of differential dynamics in the seasonality of soil moisture and its effects on soil CO2 production and flux. Our results suggest concomitant yet independent effects of water on physical (soil gas diffusivity) and biological (photosynthetic discrimination) processes that mediate δS and δP and are important when evaluating the δ13C of CO2 exchanged between soils and the atmosphere in complex terrain.

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Environmental forcing does not induce diel or synoptic variation in the carbon isotope content of forest soil respiration

Abstract: Abstract. Recent studies have examined temporal fluctuations in the amount and carbon isotope content (δ 13

Cited by 39 publications

References 85 publications

Seasonal Bias in Soil Carbonate Formation and Its Implications for Interpreting High‐Resolution Paleoarchives: Evidence From Southern Utah

Seasonal Bias in Soil Carbonate Formation and Its Implications for Interpreting High‐Resolution Paleoarchives: Evidence From Southern Utah

Carbon isotopic composition of forest soil respiration in the decade following bark beetle and stem girdling disturbances in the Rocky Mountains

Spatial and seasonal variabilities of the stable carbon isotope composition of soil CO₂ concentration and flux in complex terrain

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Environmental forcing does not induce diel or synoptic variation in the carbon isotope content of forest soil respiration

Abstract: Abstract. Recent studies have examined temporal fluctuations in the amount and carbon isotope content (δ 13

Cited by 39 publications

References 85 publications

Seasonal Bias in Soil Carbonate Formation and Its Implications for Interpreting High‐Resolution Paleoarchives: Evidence From Southern Utah

Seasonal Bias in Soil Carbonate Formation and Its Implications for Interpreting High‐Resolution Paleoarchives: Evidence From Southern Utah

Carbon isotopic composition of forest soil respiration in the decade following bark beetle and stem girdling disturbances in the Rocky Mountains

Spatial and seasonal variabilities of the stable carbon isotope composition of soil CO2 concentration and flux in complex terrain

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Spatial and seasonal variabilities of the stable carbon isotope composition of soil CO₂ concentration and flux in complex terrain