Temperature Dependence of Soil Respiration Modulated by Thresholds in Soil Water Availability Across European Shrubland Ecosystems

Abstract

The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. Author Contributions: EKL and ELK conceived the study; ELK, GDD, ME, GG, GRK, GKD, KSL, JP, ARS, AS, AT and IKS performed the research; BDZ and ELK analyzed the data; and ELK wrote the paper. 2 Abstract Soil respiration (SR) is a major component of the global carbon cycle and plays a fundamental role in ecosystem feedback to climate change. Empirical modelling is an essential tool for predicting ecosystem responses to environmental change, and also provides important data for calibrating and corroborating process-based models. In this study, we evaluated the performance of three empirical temperature-SR response functions (exponential, Lloyd-Taylor and Gaussian) at seven shrublands located within three climatic regions (Atlantic, Mediterranean and Continental) across Europe. We investigated the performance of SR models by including interaction between soil moisture and soil temperature. We found that the best fit for the temperature functions depended on the site specific climatic conditions. Including soil moisture, we identified thresholds in the three different response functions that improved the model fit in all cases. The direct soil moisture effect on SR, however, was weak at the annual time scale. We conclude that the exponential soil temperature function may only be a good predictor for SR in a narrow temperature range, and that extrapolating predictions for future climate based on this function should be treated with caution as modelled outputs may underestimate SR. The addition of soil moisture thresholds improved the model fit at all sites, but had a far greater ecological significance in the wet Atlantic shrubland where a fundamental change in the soil CO2 efflux would likely have an impact on the whole carbon budget. Type of Paper: Original Article

Ecosystem controlled soil-rock pCO2 and carbonate weathering – Constraints by temperature and soil water content

“…This implies that the underground production of CO 2 related to CaCO 3 -H 2 O-CO 2 system should lead to a partial pressure of approximately 0.01 atm, if a closed system is considered. However, the minimum value of pCO 2 calculated considering an open system (0.00049 atm) is close to atmospheric pCO 2 , which is comparable to results from respiration models (Cerling et al, 1991;Frisia et al, 2011;Lellei-Kovács et al, 2016;Suseela et al, 2012).…”

“…In addition, temperature controls biological activity and thus influences soil pCO 2 . Soil respiration is often described as being directly proportional to temperature (Lellei-Kovács et al, 2016;Lloyd and Taylor, 1994). Therefore, the function developed to calculate the logarithm of the partial pressure of CO 2 in the soil (log 10 pCO 2 ) is represented by the following equation and based on findings from Fig where θ represents the mean annual volumetric water content (v/v); T is the mean annual surface temperature in degrees Celsius, log 10 pCO 2atm is the logarithm of partial pressure of CO 2 in the atmosphere (a value of −3.4 was considered in this work); b 1 , b 2 , b 3 and b 4 are fitted constants with average values of −3.0 ± 0.7, −0.25 ± 0.04, 0.09 ± 0.03 and −0.34 ± 0.05, respectively.…”

The Response of Soil CO2 Efflux to Water Limitation Is Not Merely a Climatic Issue: The Role of Substrate Availability

“…This difference was attributable to the concurrent reversed sign of the correlation SR-SWC, confirming the stronger role of SWC than the solely temperature in regulating SR in dry ecosystems subjected to drought. These results are in line with the most recent outcomes on SR modelling in ecosystems facing drought, pointing to include soil moisture, inversely related to soil temperature [53][54][55].…”

Relationship between root water uptake and soil respiration: A modeling perspective

“…Since soil water content is one of the key variables regulating soil CO 2 production and efflux [ Hanson et al , ; Davidson et al , ; Almagro et al , ; Liu et al , ; Carbone et al , ; Suseela et al , ; Balogh et al , ; Reynolds et al , ; Lellei‐Kovács et al , ], root water uptake mechanisms might play an important role in controlling CO 2 fluxes. Mechanistic models have been developed for CO 2 production and transport to adequately describe vertical gaseous diffusion and dispersion as a function of soil water content and temperature [ Patwardhan et al , ; Simunek and Suarez , ; Fang and Moncrieff , ].…”