Direct and legacy effects of varying cool-season precipitation totals on ecosystem carbon flux in a semi-arid mixed grassland

Fangyue Zhang; Joel A. Biederman; Nathan A. Pierce; Daniel L. Potts; Sasha C. Reed; William K. Smith

doi:10.1111/pce.15175

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Direct and legacy effects of varying cool-season precipitation totals on ecosystem carbon flux in a semi-arid mixed grassland

Fangyue Zhang·Joel A. Biederman·Nathan A. Pierce·Daniel L. Potts·Sasha C. Reed·William K. Smith

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Abstract

In the semi-arid grasslands of the southwest United States, annual precipitation is divided between warm-season (July–September) convective precipitation and cool-season (December–March) frontal storms. While evidence suggests shifts in precipitation seasonal distribution, there is a poor understanding of the ecosystem carbon flux responses to cool-season precipitation and the potential legacy effects on subsequent warm-season carbon fluxes. Results from a two-year experiment with three cool-season precipitation treatments (dry, received 5th percentile cool-season total precipitation; normal, 50th; wet, 95th) and constant warm-season precipitation illustrate the direct and legacy effects on carbon fluxes, but in opposing ways. In wet cool-season plots, gross primary productivity (GPP) and ecosystem respiration (ER) were 103% and 127% higher than in normal cool-season plots. In dry cool-season plots, GPP and ER were 47% and 85% lower compared to normal cool-season plots. Unexpectedly, we found a positive legacy effect of the dry cool-season treatment on warm-season carbon flux, resulting in a significant increase in both GPP and ER in the subsequent warm season, compared to normal cool-season plots. Our results reveal positive legacy effects of cool-season drought on warm-season carbon fluxes and highlight the importance of the relatively under-studied cool-growing season and its direct/indirect impact on the ecosystem carbon budget.

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Source-reported bounding extent: 25.08° to 49.38905° latitude; -124.68721° to -66.96466° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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BibTeX RIS

Fangyue Zhang, Joel A. Biederman, Nathan A. Pierce, Daniel L. Potts, Sasha C. Reed, William K. Smith. 2024-10-07. Direct and legacy effects of varying cool-season precipitation totals on ecosystem carbon flux in a semi-arid mixed grassland. https://doi.org/10.1111/pce.15175

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