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Temperature response of soil respiration in a Chinese pine plantation: hysteresis and seasonal vs. diel Q10.

Jia X, Zha T, Wu B, Zhang Y, Chen W, Wang X, Yu H, He G - PLoS ONE (2013)

Bottom Line: Progress on these issues will contribute to reduced uncertainties in carbon cycle modeling.The hysteresis may be associated with the confounding effects of microbial population dynamics and/or litter input.In addition, daily Q10 decreased with increasing Ts , which may contribute feedback to the climate system under global warming scenarios.

View Article: PubMed Central - PubMed

Affiliation: School of Soil and Water Conservation, Beijing Forestry University, Beijing, China.

ABSTRACT
Although the temperature response of soil respiration (Rs ) has been studied extensively, several issues remain unresolved, including hysteresis in the Rs -temperature relationship and differences in the long- vs. short-term Rs sensitivity to temperature. Progress on these issues will contribute to reduced uncertainties in carbon cycle modeling. We monitored soil CO2 efflux with an automated chamber system in a Pinus tabulaeformis plantation near Beijing throughout 2011. Soil temperature at 10-cm depth (Ts ) exerted a strong control over Rs , with the annual temperature sensitivity (Q10) and basal rate at 10°C (Rs10) being 2.76 and 1.40 µmol m(-2) s(-1), respectively. Both Rs and short-term (i.e., daily) estimates of Rs10 showed pronounced seasonal hysteresis with respect to Ts , with the efflux in the second half of the year being larger than that early in the season for a given temperature. The hysteresis may be associated with the confounding effects of microbial population dynamics and/or litter input. As a result, all of the applied regression models failed to yield unbiased estimates of Rs over the entire annual cycle. Lags between Rs and Ts were observed at the diel scale in the early and late growing season, but not in summer. The seasonality in these lags may be due to the use of a single Ts measurement depth, which failed to represent seasonal changes in the depth of CO2 production. Daily estimates of Q10 averaged 2.04, smaller than the value obtained from the seasonal relationship. In addition, daily Q10 decreased with increasing Ts , which may contribute feedback to the climate system under global warming scenarios. The use of a fixed, universal Q10 is considered adequate when modeling annual carbon budgets across large spatial extents. In contrast, a seasonally-varying, environmentally-controlled Q10 should be used when short-term accuracy is required.

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Related in: MedlinePlus

Soil temperature (Ts) (A), volumetric water content (VWC) (B) and soil respiration (Rs) (C).Ts and VWC were monitored at 10-cm depth. Solid lines: mean across measurement locations; light grey: standard deviation among measurement locations; dark grey: range among measurement locations; black dots in (C): coefficient of variation (CV) for Rs.
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pone-0057858-g001: Soil temperature (Ts) (A), volumetric water content (VWC) (B) and soil respiration (Rs) (C).Ts and VWC were monitored at 10-cm depth. Solid lines: mean across measurement locations; light grey: standard deviation among measurement locations; dark grey: range among measurement locations; black dots in (C): coefficient of variation (CV) for Rs.

Mentions: The half-hourly CO2 effluxes were screened as follows. Values outside the range of −5 to 20 µmol m−2 s−1 were considered abnormal and removed from the dataset. A mean ± 5SD criterion was then applied to monthly datasets to exclude outliers 1]. Instrument failure and quality control together resulted in 31% to 39% missing values for different chambers in 2011 (Fig. 1C). The remaining Rs data spanned the annual cycles of both Ts and VWC, allowing us to examine the relationships between Rs and its regulating factors. In order to estimate annual Rs, missing Ts values were gap-filled using empirical relationships to half-hourly soil temperatures recorded at an eddy-covariance tower 30 m away. When the tower measurements were also missing, the mean diurnal variation (MDV) method 20] with weekly windows was used to fill gaps in Ts.


Temperature response of soil respiration in a Chinese pine plantation: hysteresis and seasonal vs. diel Q10.

Jia X, Zha T, Wu B, Zhang Y, Chen W, Wang X, Yu H, He G - PLoS ONE (2013)

Soil temperature (Ts) (A), volumetric water content (VWC) (B) and soil respiration (Rs) (C).Ts and VWC were monitored at 10-cm depth. Solid lines: mean across measurement locations; light grey: standard deviation among measurement locations; dark grey: range among measurement locations; black dots in (C): coefficient of variation (CV) for Rs.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585128&req=5

pone-0057858-g001: Soil temperature (Ts) (A), volumetric water content (VWC) (B) and soil respiration (Rs) (C).Ts and VWC were monitored at 10-cm depth. Solid lines: mean across measurement locations; light grey: standard deviation among measurement locations; dark grey: range among measurement locations; black dots in (C): coefficient of variation (CV) for Rs.
Mentions: The half-hourly CO2 effluxes were screened as follows. Values outside the range of −5 to 20 µmol m−2 s−1 were considered abnormal and removed from the dataset. A mean ± 5SD criterion was then applied to monthly datasets to exclude outliers 1]. Instrument failure and quality control together resulted in 31% to 39% missing values for different chambers in 2011 (Fig. 1C). The remaining Rs data spanned the annual cycles of both Ts and VWC, allowing us to examine the relationships between Rs and its regulating factors. In order to estimate annual Rs, missing Ts values were gap-filled using empirical relationships to half-hourly soil temperatures recorded at an eddy-covariance tower 30 m away. When the tower measurements were also missing, the mean diurnal variation (MDV) method 20] with weekly windows was used to fill gaps in Ts.

Bottom Line: Progress on these issues will contribute to reduced uncertainties in carbon cycle modeling.The hysteresis may be associated with the confounding effects of microbial population dynamics and/or litter input.In addition, daily Q10 decreased with increasing Ts , which may contribute feedback to the climate system under global warming scenarios.

View Article: PubMed Central - PubMed

Affiliation: School of Soil and Water Conservation, Beijing Forestry University, Beijing, China.

ABSTRACT
Although the temperature response of soil respiration (Rs ) has been studied extensively, several issues remain unresolved, including hysteresis in the Rs -temperature relationship and differences in the long- vs. short-term Rs sensitivity to temperature. Progress on these issues will contribute to reduced uncertainties in carbon cycle modeling. We monitored soil CO2 efflux with an automated chamber system in a Pinus tabulaeformis plantation near Beijing throughout 2011. Soil temperature at 10-cm depth (Ts ) exerted a strong control over Rs , with the annual temperature sensitivity (Q10) and basal rate at 10°C (Rs10) being 2.76 and 1.40 µmol m(-2) s(-1), respectively. Both Rs and short-term (i.e., daily) estimates of Rs10 showed pronounced seasonal hysteresis with respect to Ts , with the efflux in the second half of the year being larger than that early in the season for a given temperature. The hysteresis may be associated with the confounding effects of microbial population dynamics and/or litter input. As a result, all of the applied regression models failed to yield unbiased estimates of Rs over the entire annual cycle. Lags between Rs and Ts were observed at the diel scale in the early and late growing season, but not in summer. The seasonality in these lags may be due to the use of a single Ts measurement depth, which failed to represent seasonal changes in the depth of CO2 production. Daily estimates of Q10 averaged 2.04, smaller than the value obtained from the seasonal relationship. In addition, daily Q10 decreased with increasing Ts , which may contribute feedback to the climate system under global warming scenarios. The use of a fixed, universal Q10 is considered adequate when modeling annual carbon budgets across large spatial extents. In contrast, a seasonally-varying, environmentally-controlled Q10 should be used when short-term accuracy is required.

Show MeSH
Related in: MedlinePlus