Global spatiotemporal distribution of soil respiration modeled using a global database

摘要

The flux of carbon dioxide from the soil to the atmosphere (soil respiration)is one of the major fluxes in the global carbon cycle. At present, theaccumulated field observation data cover a wide range of geographicallocations and climate conditions. However, there are still largeuncertainties in the magnitude and spatiotemporal variation of global soilrespiration. Using a global soil respiration data set, we developed aclimate-driven model of soil respiration by modifying and updating Raich'smodel, and the global spatiotemporal distribution of soil respiration wasexamined using this model. The model was applied at a spatial resolution of0.5°and a monthly time step. Soil respiration was divided into theheterotrophic and autotrophic components of respiration using an empiricalmodel. The estimated mean annual global soil respiration was91 Pg C yr?1 (between 1965 and 2012; Monte Carlo 95 % confidenceinterval: 87–95 Pg C yr?1) and increased at the rate of0.09 Pg C yr?2. The contribution of soil respiration from borealregions to the total increase in global soil respiration was on the sameorder of magnitude as that of tropical and temperate regions, despite a lowerabsolute magnitude of soil respiration in boreal regions. The estimatedannual global heterotrophic respiration and global autotrophic respirationwere 51 and 40 Pg C yr?1, respectively. The global soil respirationresponded to the increase in air temperature at the rate of3.3 Pg C yr?1 °C?1, and Q₁₀ = 1.4. Our study scaledup observed soil respiration values from field measurements to estimateglobal soil respiration and provide a data-oriented estimate of global soilrespiration. The estimates are based on a semi-empirical model parameterizedwith over one thousand data points. Our analysis indicates that the climatecontrols on soil respiration may translate into an increasing trend in globalsoil respiration and our analysis emphasizes the relevance of the soil carbon flux fromsoil to the atmosphere in response to climate change. Further approachesshould additionally focus on climate controls in soil respiration incombination with changes in vegetation dynamics and soil carbon stocks, alongwith their effects on the long temporal dynamics of soil respiration. Weexpect that these spatiotemporal estimates will provide a benchmark forfuture studies and also help to constrain process-oriented models.