Soil carbon dioxide response to meteorology in a Neotropical wet forest

Repository for <b>Precipitation‐drainage cycles lead to hot moments in soil carbon dioxide dynamics in a Neotropical wet forest</b>, in <i>Global Change Biology</i>, by Fernandez-Bou et al., 2020. https://doi.org/10.1111/gcb.15194 <br>Soil CO₂ concentrations and emissions from tropical forests are modulated seasonally by precipitation. However, sub-seasonal responses to meteorological events (for example, storms, drought) are less well-known. Here we present the effects of meteorological variability on short-term (hours to months) dynamics of soil CO₂ concentrations and emissions in a Neotropical wet forest. We continuously monitored soil temperature, moisture, and CO₂ for a three-year period (2015 to 2017), encompassing normal conditions, floods, a dry El Niño period, and a hurricane. We used a coupled model (Hydrus-1D) for soil water propagation, heat transfer, and diffusive-gas transport to explain observed soil moisture, soil temperature, and soil CO₂ concentration responses to meteorology, and we estimated soil CO₂ efflux with a gradient-flux model. Then, we predicted changes in soil CO₂ concentrations and emissions under different warming climate change scenarios. Observed short-term (hourly to daily) soil CO₂ concentration responded more to precipitation than to other meteorological variables (including lower pressure during the hurricane). Observed soil CO₂ failed to exhibit diel patterns (associated with diel temperature fluctuations in drier climates), except during the drier El Niño period. Climate change scenarios showed enhanced soil CO₂ due to warmer conditions, while precipitation played a critical role in moderating the balance between concentrations and emissions. The scenario with increased precipitation (based on a regional model projection) led to increases of +11 % in soil CO₂ concentrations and +4 % in soil CO₂ emissions. The scenario with decreased precipitation (based on global circulation model projections) resulted in increases of +4 % in soil CO₂ concentrations and +18 % in soil CO₂ emissions, and presented more prominent hot moments in soil CO₂ outgassing. These findings suggest that soil CO₂ will increase under warmer climate in tropical wet forests, and precipitation patterns will define the intensity of CO₂ outgassing hot moments.<br>