Biotic soil-plant interaction processes explain most of hysteretic soil CO2 efflux response to temperature in cross-factorial mesocosm experiment

Abstract

Ecosystem carbon flux partitioning is strongly influenced by poorly constrained soil CO 2 efflux (F soil). Simple model applications (Arrhenius and Q 10) do not account for observed diel hysteresis between F soil 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 f soil-T hysteresis. We hypothesized a principally biological cause for the hysteresis. Alternatively, F soil hysteresis is primarily driven by thermal convection through the soil profile. We conducted experiments under normal, fluctuating diurnal soil temperatures and under conditions where we held soil temperature near constant. We found (i) significant 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 F soil , which were mostly driven by photosynthetic rates. Together, these findings suggest a more biologically-driven mechanism associated with photosynthate transport in yielding the observed patterns of soil CO 2 efflux being out of sync with soil temperature. These findings should be considered on future partitioning models of ecosystem respiration. A major challenge in terrestrial carbon science is identifying atmospheric CO 2 source and sink dynamics across numerous timescales 1-3. Because CO 2 efflux (F soil) can be the largest and most variable component flux in many ecosystems 4 , F soil drives regional carbon dynamics 5,6. Accurate measurements of F soil are critical for partitioning net ecosystem CO 2 flux (NEE) and modeling local-to-global carbon dynamics 4,7,8. Nighttime ecosystem respiration (R eco) can be un-measurable using the eddy covariance (EC) technique because of a lack of turbulence and atmospheric mixing, requiring gap-filling procedures to produce credible sums 7. These missing nighttime

Hydraulic redistribution buffers climate variability and regulates grass‐tree interactions in a semiarid riparian savanna

“…These findings suggest that a site's annual HRR likely modulates a significant portion of ecosystem respiration. Coupled to recent experimental evidence about the impact of plant functional type, interstorm duration and antecedent soil moisture on diurnal patterns of soil CO 2 efflux (Dusza et al, 2020), the current results support that knowledge about a site's HRR variability may also influence the fidelity of numerical soil CO 2 efflux predictions.…”

Flux intensity and diurnal variability of soil N2O emissions in a highly fertilized cropping system

“…(2016), we believe that a more logical explanation is that the dominant source of N 2 O production in this chamber was at a depth where soil temperature changes lagged the other three chambers, as suggested by Dusza et al. (2020) and Parkin (1987). Although the fluxes measured in this one chamber exhibited an inverted diurnal pattern relative to the others, the PMTs found for the four chambers were the same.…”

Synthetic Biology for Terraformation Lessons from Mars, Earth, and the Microbiome

“…Those findings have been reported in several ecosystems, globally [118] and regionally [119], and attain nitrogen cycling rates [119,120], micronutrients [121], soil fauna [122,123], changes in the relative importance of erosive agents [124], soil aggregates stability and the relationship between soils and plants [117]. Presumably, those changes would involve also a drastic change in soil microorganisms [125,126], which are the main biotic agents driving and connecting soil nutrients and stocks [127,128] and contribute importantly to enhance soil stability and water capacity. [100,111,129].…”