Soil water content effects on net ecosystem CO2 exchange and actual evapotranspiration in a Mediterranean semiarid savanna of Central Chile
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Meza, Francisco J.; Montes, Carlo; Bravo-Martínez, Felipe; Serrano Ortiz, Penélope; Kowalski, AndrewEditorial
Springer Nature
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2018-06-05Referencia bibliográfica
Meza, Francisco J.; et. al. Soil water content effects on net ecosystem CO2 exchange and actual evapotranspiration in a Mediterranean semiarid savanna of Central Chile. ScientiFic Reports (2018) 8:8570 [https://doi.org/10.1038/s41598-018-26934-z]
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This work was funded by FONDECYT projects 1120713 and 1170429, a grant from the Inter-American Institute for Global Change Research (IAI) [grant number CRN3056], which is supported by the US National Science Foundation [grant number GEO-1128040], and the Spanish Ministry of Economy and Competitiveness project GEI Spain (CGL2014-52838-C2-1-R), including ERDF founds. F. Bravo-Martínez is grateful to CONICYT for the grants “Formación de Capital Humano Avanzado-2009′′, “Beca de Apoyo al término de la tesis doctoral-2012′′, and CORFO INNOVA Grant N° 09CN14-5704. We thank to Enrique Pérez Sanchez-Cañete and Borja Ruíz- Reverter for technical support. We also thank “CODELCO–División Andina” for use of the site. C. Montes acknowledges the NASA Postdoctoral Program and to Universities Space Research Association.Resumen
Biosphere-atmosphere water and carbon fluxes depend on ecosystem structure, and their magnitudes
and seasonal behavior are driven by environmental and biological factors. We studied the seasonal
behavior of net ecosystem CO2 exchange (NEE), Gross Primary Productivity (GPP), Ecosystem
Respiration (RE), and actual evapotranspiration (ETa) obtained by eddy covariance measurements
during two years in a Mediterranean Acacia savanna ecosystem (Acacia caven) in Central Chile. The
annual carbon balance was −53 g C m−2 in 2011 and −111 g C m−2 in 2012, showing that the ecosystem
acts as a net sink of CO2, notwithstanding water limitations on photosynthesis observed in this
particularly dry period. Total annual ETa was of 128 mm in 2011 and 139 mm in 2012. Both NEE and ETa
exhibited strong seasonality with peak values recorded in the winter season (July to September), as a
result of ecosystem phenology, soil water content and rainfall occurrence. Consequently, the maximum
carbon assimilation rate occurred in wintertime. Results show that soil water content is a major driver
of GPP and RE, defining their seasonal patterns and the annual carbon assimilation capacity of the
ecosystem, and also modulating the effect that solar radiation and air temperature have on NEE
components at shorter time scales.