Biotic soil-plant interaction processes explain most of hysteretic soil CO2 efux response to temperature in cross-factorial mesocosm experiment
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Dusza, Y., Sanchez-Cañete, E. P., Le Galliard, J. F., Ferriere, R., Chollet, S., Massol, F., ... & Troch, P. (2020). Biotic soil-plant interaction processes explain most of hysteric soil CO 2 efflux response to temperature in cross-factorial mesocosm experiment. Scientific reports, 10(1), 1-11. [https://doi.org/10.1038/s41598-019-55390-6]
SponsorshipFrench government; French National Research Agency (ANR) ANR-10-IDEX-0001-02 PSL ANR-11-INBS-0001; ENS; University of Arizona (UofA); Philecology Foundation (Fort Worth, Texas, USA); Thomas R. Brown Family Foundation; Region Ile-de-France I-05-098/R 2011-11017735; European Union (EU); National Science Foundation (NSF) 1417101 1331408; European Union (EU) 625988; UofA Office of Global Initiatives; Office of the Vice President of Research at the UofA; UMI iGLOBES program at the UofA
Ecosystem carbon fux partitioning is strongly infuenced by poorly constrained soil CO2 efux (Fsoil). Simple model applications (Arrhenius and Q10) do not account for observed diel hysteresis between Fsoil and soil temperature. How this hysteresis emerges and how it will respond to variation in vegetation or soil moisture remains unknown. We used an ecosystem-level experimental system to independently control potential abiotic and biotic drivers of the Fsoil-T hysteresis. We hypothesized a principally biological cause for the hysteresis. Alternatively, Fsoil hysteresis is primarily driven by thermal convection through the soil profle. We conducted experiments under normal, fuctuating diurnal soil temperatures and under conditions where we held soil temperature near constant. We found (i) signifcant and nearly equal amplitudes of hysteresis regardless of soil temperature regime, and (ii) the amplitude of hysteresis was most closely tied to baseline rates of Fsoil, which were mostly driven by photosynthetic rates. Together, these fndings suggest a more biologically-driven mechanism associated with photosynthate transport in yielding the observed patterns of soil CO2 efux being out of sync with soil temperature. These fndings should be considered on future partitioning models of ecosystem respiration.