The sensitivity of North American terrestrial carbon fluxes to spatial and temporal variation in soil moisture: an analysis using radar‐derived estimates of root zone soil moisture

Zhang, Ke, Ali, Ashehad, Antonarakis, Alexander, Moghaddam, Mahta, Saatchi, Sassan, Tabatabaeenejad, Alireza, Chen, Richard, Jaruwatanadilok, Sermsak, Cuenca, Richard, Crow, Wade T and Moorcroft, Paul (2019) The sensitivity of North American terrestrial carbon fluxes to spatial and temporal variation in soil moisture: an analysis using radar‐derived estimates of root zone soil moisture. Journal of Geophysical Research: Biogeosciences. ISSN 2169-8961

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Abstract

This study examines the impact of variation in Root‐Zone Soil Moisture (RZSM), a key component of the Earth's hydrologic cycle and climate system, on regional carbon fluxes across seven North American ecosystems. P‐band Synthetic Aperture Radar‐derived RZSM estimates were incorporated into the Ecosystem Demography (ED2) terrestrial biosphere model through a model‐data blending approach. Analysis shows that the model qualitatively captures inter‐daily and seasonal variability of observed RZSM at seven flux tower sites (r=0.59 ± 0.26 and r= 0.70 ± 0.22 for 0‐10cm and 10‐40cm soil layers, respectively; P<0.001). Incorporating the remotely‐sensed RSZM estimates increases the accuracy (root‐mean‐square deviations decrease from 0.10 ± 0.07 m3m‐3 and 0.09 ± 0.06 m3m‐3 to 0.08 ± 0.05 m3m‐3 and 0.07 ± 0.03 m3m‐3 for 0‐10 cm and 10‐40 cm soil layers, respectively) of the model's RZSM predictions. The regional carbon fluxes predicted by the native and RZSM‐constrained model were used to quantify sensitivities of gross primary productivity (GPP), autotrophic respiration (Ra), heterotrophic respiration (Rh) and net ecosystem exchange (NEE) to variation in RZSM. GPP exhibited the largest sensitivity (6.6 ± 10.7 kgCm‐2 y‐1θ‐1) followed by Ra (2.9 ± 7.3 kgCm‐2 y‐1θ‐1), Rh (2.6 ± 3.1kg Cm‐2 y‐1θ‐1), and NEE (‐1.7 ± 7.8 kgCm‐2 y‐1θ‐1). Analysis shows that these carbon flux sensitivities varied considerably across regions, reflecting influences of canopy structure, soil properties, and the eco‐physiological properties of different plant functional types. This study highlights (1) the importance of: improved terrestrial biosphere model predictions of RZSM to improve predictions of terrestrial carbon fluxes, (2) improved pedotransfer functions, and (3) improved understanding of how soil characteristics, climate, and vegetation composition interact to govern the responses of different ecosystems to changing hydrological conditions.

Item Type: Article
Schools and Departments: School of Global Studies > Geography
Research Centres and Groups: climate@sussex
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
G Geography. Anthropology. Recreation > GB Physical geography > GB0651 Hydrology. Water (Ground and surface waters)
Q Science > QC Physics > QC0851 Meteorology. Climatology Including the earth's atmosphere > QC0903 Variations. Climatic changes. Including global temperature changes, etc.
Q Science > QC Physics > QC0851 Meteorology. Climatology Including the earth's atmosphere > QC0901-0913 Temperature and radiation > QC0901-0906 Atmospheric temperature > QC0903 Variations. Climatic changes. Including global temperature changes, etc.
Q Science > QH Natural history > QH0301 Biology > QH0540 Ecology
Depositing User: Alexander Antonarakis
Date Deposited: 11 Oct 2019 14:49
Last Modified: 11 Oct 2019 14:49
URI: http://sro.sussex.ac.uk/id/eprint/87018

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Project NameSussex Project NumberFunderFunder Ref
AirMOSSUnsetNational Aeronautical and Space AdministrationNASA Earth Venture-1 09-EV109-0006