Environmental and Vegetative Controls on Soil CO2 Efflux in Three Semiarid Ecosystems
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Author
Roby, Matthew C.Scott, Russell L.
Barron-Gafford, Greg A.
Hamerlynck, Erik P.
Moore, David J. P.
Affiliation
Univ Arizona, Sch Nat Resources & Environm, Tucson, AZ 85721 USAUniv Arizona, Sch Geog & Dev, Tucson, AZ 85721 USA
Univ Arizona, Coll Sci, Biosphere 2, Tucson, AZ 85721 USA
Issue Date
2019-01-08Keywords
soil respirationdrylands
water availability
spatial variation
temporal dynamics
pulses
photosynthesis
ecosystem respiration
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MDPICitation
Roby, M.C.; Scott, R.L.; Barron-Gafford, G.A.; Hamerlynck, E.P.; Moore, D.J.P. Environmental and Vegetative Controls on Soil CO2 Efflux in Three Semiarid Ecosystems. Soil Syst. 2019, 3, 6.Journal
SOIL SYSTEMSRights
Copyright © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Soil CO2 efflux (F-soil) is a major component of the ecosystem carbon balance. Globally expansive semiarid ecosystems have been shown to influence the trend and interannual variability of the terrestrial carbon sink. Modeling F-soil in water-limited ecosystems remains relatively difficult due to high spatial and temporal variability associated with dynamics in moisture availability and biological activity. Measurements of the processes underlying variability in F-soil can help evaluate F-soil models for water-limited ecosystems. Here we combine automated soil chamber and flux tower data with models to investigate how soil temperature (T-s), soil moisture (theta), and gross ecosystem photosynthesis (GEP) control F-soil in semiarid ecosystems with similar climates and different vegetation types. Across grassland, shrubland, and savanna sites, theta regulated the relationship between F-soil and T-s, and GEP influenced F-soil magnitude. Thus, the combination of T-s, theta, and GEP controlled rates and patterns of F-soil. In a root exclusion experiment at the grassland, we found that growing season autotrophic respiration accounted for 45% of F-soil. Our modeling results indicate that a combination of T-s, theta, and GEP terms is required to model spatial and temporal dynamics in F-soil, particularly in deeper-rooted shrublands and savannas where coupling between GEP and shallow theta is weaker than in grasslands. Together, these results highlight that including theta and GEP in F-soil models can help reduce uncertainty in semiarid ecosystem carbon dynamics.Note
Open access journalISSN
2571-8789Version
Final published versionSponsors
USDA-ARSUnited States Department of Agriculture (USDA); U.S. Department of Energy Berkeley National Labsae974a485f413a2113503eed53cd6c53
10.3390/soilsystems3010006