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ELEVATED ATMOSPHERIC CO 2 DOES NOT CONSERVE SOIL WATER IN THE MOJAVE DESERT
Author(s) -
Nowak Robert S.,
Zitzer Stephen F.,
Babcock Derek,
Smith-Longozo Vickie,
Charlet Therese N.,
Coleman James S.,
Seemann Jeffrey R.,
Smith Stanley D.
Publication year - 2004
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/03-3054
Subject(s) - soil water , environmental science , transpiration , desert (philosophy) , hydrology (agriculture) , agronomy , soil science , chemistry , geology , biology , photosynthesis , philosophy , geotechnical engineering , epistemology , biochemistry
Numerous studies, including those of desert plants, have shown reduced stomatal conductance under elevated atmospheric CO 2 . As a consequence, soil water has been postulated to increase. Soil water was measured for >4 yr at the Nevada Desert Free Air CO 2 Enrichment (FACE) Facility to determine if elevated atmospheric CO 2 conserves soil water for a desert scrub community in the Mojave Desert. We measured soil water in the top 0.2 and 0.5 m of soil with time domain reflectometry and to 1.85 m with a neutron probe for the three treatments at Desert FACE: elevated CO 2 (550 μmol/mol), blower control (ambient CO 2 ), and non‐ring treatments. The treatment main effect was not significant in any analyses of variance. Although the treatment × date interaction was significant for soil water in the top 0.5 m of soil, the expected greater soil water for elevated CO 2 vs. ambient CO 2 only occurred on one sampling date. In contrast, soil water for that same depth was significantly lower under elevated CO 2 on six dates. Thus, we infer that increased water use from increased primary productivity (and therefore leaf area) under elevated CO 2 offset the decreased water use from reduced stomatal conductance, and hence soil water was not conserved under elevated CO 2 in the Mojave Desert, unlike other ecosystems.