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Water Relations and the Maintenance of Sierran Conifers on Hydrothermally Altered Rock
Author(s) -
DeLucia Evan H.,
Schlesinger William H.,
Billings W. D.
Publication year - 1988
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1940428
Subject(s) - soil water , xylem , bedrock , environmental science , vegetation (pathology) , juniper , growing season , water content , nutrient , agronomy , ecology , biology , botany , geology , geomorphology , medicine , geotechnical engineering , pathology
Unusual, nutrient—poor soils derived from hydrothermally altered bedrock support open forests of Sierran conifers (Pinus ponderosa, P. jeffreyi, and others) amongst the sagebrush and pinyon—juniper vegetation on typical desert soils of the Great Basin in western Nevada. As an index of soil moisture availability, we compared predawn xylem pressure potential (XPP) and diurnal patterns of stomatal conductance for various species at three sites, with paired, adjacent soils derived from unaltered and hydrothermally altered parent material. At high soil moisture availability, Great Basin shurbs maintained higher maximum leaf conductance (2—3 mm/s) than Sierran conifers (<1.2 mm/s). During the growing season XPP declined for all species at all sites, but during extended drought values for Great Basin shrubs (—2.70–4.47 MPa) growing on unaltered soil were consistently lower than for Sierran conifers (—0.97_—1.12 MPa) growing onaltered soil. While few species were found on both soil types, Amelanchier alnifolia showed lower predawn XPP on soils derived from unaltered (—3.22 MPa) than from altered (—2.05 MPa) parent paterials. These data suggest that shrubs rapidly deplete soil moisture in the Great Basin desert, restricting the establishment of Sierran conifers to soils derived from altered rocks, which otherwise support minimal vegetation cover. The @° 1 3 C of foilage from conifers were higher than from Great Basin shrubs, suggesting that conifers maintain higher seasonally integrated water—use efficiencies.