TY - JOUR
T1 - The understory and overstory partitioning of energy and water fluxes in an open canopy, semiarid woodland
AU - Scott, Russell L.
AU - Watts, Christopher
AU - Payan, Jaime Garatuza
AU - Edwards, Eric
AU - Goodrich, David C.
AU - Williams, David
AU - Shuttleworth, W. James
N1 - Funding Information:
This work is supported in part by SAHRA (Sustainability of Semi-arid Hydrology and Riparian Areas) under the STC Program of the National Science Foundation, Agreement No. EAR-9876800. Additional financial support was provided to USDA-ARS from the Upper San Pedro Partnership. We would also like to thank Enrico Yepez-Gonzalez for the vegetation data, along with the Fort Huachuca Meteorological Support team, US Bureau of Land Management, and especially all the rest of the staff from the USDA-ARS located in Tucson and Tombstone, Arizona for their invaluable support of this work.
PY - 2003/1/31
Y1 - 2003/1/31
N2 - Eddy flux studies have traditionally focused on total ecosystem exchanges of energy and water by making measurements in the well-mixed surface layer, but this approach does not provide information about the partitioning of the total ecosystem fluxes between overstory and understory sources and sinks. In more open canopy environments, information about partitioning of fluxes is often required in order to understand the relative importance and functioning of key ecosystem components and their response to climate forcing. In this paper, we present results from a series of experiments carried out in a riparian mesquite (Prosopis velutina) woodland. Three eddy covariance systems were deployed before, during, and after the onset of the summer rainy season to measure energy and water fluxes. One eddy covariance system was installed on a tower to measure whole ecosystem fluxes. The other two were installed at a height of 2 m, one in a relatively closed understory patch and the other in a more open understory patch. Our results indicate that the understory and overstory moisture sources were mostly decoupled. The trees apparently had access to deep moisture sources, and thus, their water use was relatively insensitive to local precipitation. In contrast, the contribution of the understory to the total ecosystem fluxes was highly variable due to the presence or absence of near-surface soil moisture.
AB - Eddy flux studies have traditionally focused on total ecosystem exchanges of energy and water by making measurements in the well-mixed surface layer, but this approach does not provide information about the partitioning of the total ecosystem fluxes between overstory and understory sources and sinks. In more open canopy environments, information about partitioning of fluxes is often required in order to understand the relative importance and functioning of key ecosystem components and their response to climate forcing. In this paper, we present results from a series of experiments carried out in a riparian mesquite (Prosopis velutina) woodland. Three eddy covariance systems were deployed before, during, and after the onset of the summer rainy season to measure energy and water fluxes. One eddy covariance system was installed on a tower to measure whole ecosystem fluxes. The other two were installed at a height of 2 m, one in a relatively closed understory patch and the other in a more open understory patch. Our results indicate that the understory and overstory moisture sources were mostly decoupled. The trees apparently had access to deep moisture sources, and thus, their water use was relatively insensitive to local precipitation. In contrast, the contribution of the understory to the total ecosystem fluxes was highly variable due to the presence or absence of near-surface soil moisture.
KW - Eddy covariance
KW - Evapotranspiration
KW - Mesquite
KW - Prosopis velutina
KW - Savannah
KW - Transpiration rate
KW - Understory vegetation
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U2 - 10.1016/S0168-1923(02)00197-1
DO - 10.1016/S0168-1923(02)00197-1
M3 - Article
AN - SCOPUS:0037473978
VL - 114
SP - 127
EP - 139
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
SN - 0168-1923
IS - 3-4
ER -