Soil respiration response to rainfall modulated by plant phenology in a montane meadow, East River, Colorado, USA

Journal of Geophysical Research Biogeosciences
By: , and 

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Abstract

Soil respiration is a primary component of the terrestrial carbon cycle. However, predicting the response of soil respiration to climate change remains a challenge due to the complex interactions between environmental drivers, especially plant phenology, temperature, and soil moisture. In this study, we use a 1‐D diffusion‐reaction model to calculate depth‐resolved CO2 production rates from soil CO2 concentrations and surface efflux observations in a subalpine meadow in the East River watershed, CO. Modeled rates are compared to in situ soil temperature and moisture conditions and MODIS satellite enhanced vegetation index (EVI) representing plant phenology across three hydrologically distinct growing seasons from 2016–2018. While soil respiration correlated with temperature on diel timescales (p < 0.05), seasonal variability was dominated by soil moisture and plant phenology (p < 0.05). We observed significant respiration increases in response to precipitation events; however, magnitude and duration were significantly higher in 2017 than 2016 despite similar wetting characteristics. Based on MODIS EVI, we suggest that the respiration response to rainfall is controlled by plant phenology, which in turn reflects the capacity of plants to respond to precipitation via increased photosynthesis and autotrophic respiration, behavior that is not captured in typical soil respiration pulse models. Projected changes in montane climate such as earlier snowmelt and prolonged fore‐summer drought may decrease soil respiration fluxes by decreasing the overlap between peak productivity and the summer monsoon. Finally, we observed significant late season CO2 fluxes from the deep subsoil (>165 cm) that support growing evidence for the importance of subsoil processes in driving integrated respiration fluxes.

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Publication type Article
Publication Subtype Journal Article
Title Soil respiration response to rainfall modulated by plant phenology in a montane meadow, East River, Colorado, USA
Series title Journal of Geophysical Research Biogeosciences
DOI 10.1029/2020JG005924
Volume 125
Issue 10
Year Published 2020
Language English
Publisher American Geophysical Union
Contributing office(s) Geosciences and Environmental Change Science Center
Description e2020JG005924, 20 p.
Country United States
State Colorado
Other Geospatial East River watershed
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