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Separating the effects of climate and vegetation on evapotranspiration along a successional chronosequence in the southeastern US
Author(s) -
STOY PAUL C.,
KATUL GABRIEL G.,
SIQUEIRA MARIO B. S.,
JUANG JEHNYIH,
NOVICK KIMBERLY A.,
McCARTHY HEATHER R.,
CHRISTOPHER OISHI A.,
UEBELHERR JOSHUA M.,
KIM HYUNSEOK,
OREN RAM
Publication year - 2006
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2006.01244.x
Subject(s) - evapotranspiration , environmental science , chronosequence , eddy covariance , ecosystem , precipitation , growing season , atmospheric sciences , crop coefficient , hydrology (agriculture) , ecology , soil water , geography , soil science , geology , biology , geotechnical engineering , meteorology
We combined Eddy‐covariance measurements with a linear perturbation analysis to isolate the relative contribution of physical and biological drivers on evapotranspiration (ET) in three ecosystems representing two end‐members and an intermediate stage of a successional gradient in the southeastern US (SE). The study ecosystems, an abandoned agricultural field [old field (OF)], an early successional planted pine forest (PP), and a late‐successional hardwood forest (HW), exhibited differential sensitivity to the wide range of climatic and hydrologic conditions encountered over the 4‐year measurement period, which included mild and severe droughts and an ice storm. ET and modeled transpiration differed by as much as 190 and 270 mm yr −1 , respectively, between years for a given ecosystem. Soil water supply, rather than atmospheric demand, was the principal external driver of interannual ET differences. ET at OF was sensitive to climatic variability, and results showed that decreased leaf area index ( L ) under mild and severe drought conditions reduced growing season (GS) ET (ET GS ) by ca. 80 mm compared with a year with normal precipitation. Under wet conditions, higher intrinsic stomatal conductance ( g s ) increased ET GS by 50 mm. ET at PP was generally larger than the other ecosystems and was highly sensitive to climate; a 50 mm decrease in ET GS due to the loss of L from an ice storm equaled the increase in ET from high precipitation during a wet year. In contrast, ET at HW was relatively insensitive to climatic variability. Results suggest that recent management trends toward increasing the land‐cover area of PP‐type ecosystems in the SE may increase the sensitivity of ET to climatic variability.