Limits...
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.

Show MeSH

Related in: MedlinePlus

Daily Rs10 (A), daily Q10 (B) and diel lags (lagmax) (C).Rs10 refers to the basal rate of soil respiration at 10°C. Lagmax indicates the temporal lag that maximizes the correlation between soil respiration (Rs) and 10-cm soil temperature (Ts) over the diel cycle. Circles in (A–C): mean across measurement locations; grey area in (A and B): range among measurement locations; black dots in (A and B): coefficients of variation (CV) for Rs10 and Q10, respectively.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3585128&req=5

pone-0057858-g004: Daily Rs10 (A), daily Q10 (B) and diel lags (lagmax) (C).Rs10 refers to the basal rate of soil respiration at 10°C. Lagmax indicates the temporal lag that maximizes the correlation between soil respiration (Rs) and 10-cm soil temperature (Ts) over the diel cycle. Circles in (A–C): mean across measurement locations; grey area in (A and B): range among measurement locations; black dots in (A and B): coefficients of variation (CV) for Rs10 and Q10, respectively.

Mentions: Both diel estimates of Rs10 and Q10 showed strong seasonal trends (Fig. 4). Only the period from March to November is shown, as Rs values were so small and Ts oscillated so weakly in winter that the regressions produced unreasonable parameter estimates. Mean Rs10 across locations was <1.0 µmol m−2 s−1 in early March, increased throughout April to June, peaked in early August (∼4.5 µmol m−2 s−1), and then decreased to ∼1.50 µmol m−2 s−1 in November (Fig. 4A). Q10 was generally low in summer (1.5–2.0), but high at both ends of the growing season (2.0–4.0) (Fig. 4B). A peak in Q10 was evident between March and April.


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)

Daily Rs10 (A), daily Q10 (B) and diel lags (lagmax) (C).Rs10 refers to the basal rate of soil respiration at 10°C. Lagmax indicates the temporal lag that maximizes the correlation between soil respiration (Rs) and 10-cm soil temperature (Ts) over the diel cycle. Circles in (A–C): mean across measurement locations; grey area in (A and B): range among measurement locations; black dots in (A and B): coefficients of variation (CV) for Rs10 and Q10, respectively.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0057858-g004: Daily Rs10 (A), daily Q10 (B) and diel lags (lagmax) (C).Rs10 refers to the basal rate of soil respiration at 10°C. Lagmax indicates the temporal lag that maximizes the correlation between soil respiration (Rs) and 10-cm soil temperature (Ts) over the diel cycle. Circles in (A–C): mean across measurement locations; grey area in (A and B): range among measurement locations; black dots in (A and B): coefficients of variation (CV) for Rs10 and Q10, respectively.
Mentions: Both diel estimates of Rs10 and Q10 showed strong seasonal trends (Fig. 4). Only the period from March to November is shown, as Rs values were so small and Ts oscillated so weakly in winter that the regressions produced unreasonable parameter estimates. Mean Rs10 across locations was <1.0 µmol m−2 s−1 in early March, increased throughout April to June, peaked in early August (∼4.5 µmol m−2 s−1), and then decreased to ∼1.50 µmol m−2 s−1 in November (Fig. 4A). Q10 was generally low in summer (1.5–2.0), but high at both ends of the growing season (2.0–4.0) (Fig. 4B). A peak in Q10 was evident between March and April.

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