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Antecedent moisture and seasonal precipitation influence the response of canopy‐scale carbon and water exchange to rainfall pulses in a semi‐arid grassland
Author(s) -
Potts D. L.,
Huxman T. E.,
Cable J. M.,
English N. B.,
Ignace D. D.,
Eilts J. A.,
Mason M. J.,
Weltzin J. F.,
Williams D. G.
Publication year - 2006
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2006.01732.x
Subject(s) - arid , grassland , environmental science , precipitation , antecedent moisture , moisture , canopy , scale (ratio) , evapotranspiration , atmospheric sciences , water content , hydrology (agriculture) , antecedent (behavioral psychology) , agronomy , ecology , surface runoff , biology , geology , meteorology , geography , geotechnical engineering , psychology , developmental psychology , cartography , runoff curve number
Summary• The influences of prior monsoon‐season drought (PMSD) and the seasonal timing of episodic rainfall (‘pulses’) on carbon and water exchange in water‐limited ecosystems are poorly quantified. • In the present study, we estimated net ecosystem exchange of CO 2 (NEE) and evapotranspiration (ET) before, and for 15 d following, experimental irrigation in a semi‐arid grassland during June and August 2003. Rainout shelters near Tucson, Arizona, USA, were positioned on contrasting soils (clay and sand) and planted with native ( Heteropogon contortus ) or non‐native invasive ( Eragrostis lehmanniana ) C4 bunchgrasses. Plots received increased (‘wet’) or decreased (‘dry’) monsoon‐season (July–September) rainfall during 2002 and 2003. • Following a June 2003 39‐mm pulse, species treatments had similar NEE and ET dynamics including 15‐d integrated NEE (NEE pulse ). Contrary to predictions, PMSD increased net C uptake during June in plots of both species. Greater flux rates after an August 2003 39‐mm pulse reflected biotic activity associated with the North American Monsoon. Furthermore, August NEE pulse and ecosystem pulse‐use efficiency (PUE e = NEE pulse /ET pulse ) was greatest in Heteropogon plots. • PMSD and rainfall seasonal timing may interact with bunchgrass invasions to alter NEE and ET dynamics with consequences for PUE e in water‐limited ecosystems.