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Title: Precipitation‐drainage cycles lead to hot moments in soil carbon dioxide dynamics in a Neotropical wet forest

Soil CO2concentrations and emissions from tropical forests are modulated seasonally by precipitation. However, subseasonal responses to meteorological events (e.g., storms, drought) are less well known. Here, we present the effects of meteorological variability on short‐term (hours to months) dynamics of soil CO2concentrations and emissions in a Neotropical wet forest. We continuously monitored soil temperature, moisture, and CO2for a three‐year period (2015–2017), 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 CO2concentration responses to meteorology, and we estimated soil CO2efflux with a gradient‐flux model. Then, we predicted changes in soil CO2concentrations and emissions under different warming climate change scenarios. Observed short‐term (hourly to daily) soil CO2concentration responded more to precipitation than to other meteorological variables (including lower pressure during the hurricane). Observed soil CO2failed 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 CO2due 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 CO2concentrations and +4% in soil CO2emissions. The scenario with decreased precipitation (based on global circulation model projections) resulted in increases of +4% in soil CO2concentrations and +18% in soil CO2emissions, and presented more prominent hot moments in soil CO2outgassing. These findings suggest that soil CO2will increase under warmer climate in tropical wet forests, and precipitation patterns will define the intensity of CO2outgassing hot moments.

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Author(s) / Creator(s):
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Publisher / Repository:
Date Published:
Journal Name:
Global Change Biology
Page Range / eLocation ID:
p. 5303-5319
Medium: X
Sponsoring Org:
National Science Foundation
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