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Mediterranean climate effects. I. Conifer water use across a Sierra Nevada ecotone
Author(s) -
Royce E. B.,
Barbour M. G.
Publication year - 2001
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.2307/2657044
Subject(s) - ecotone , evergreen , environmental science , water content , xylem , growing season , soil water , mediterranean climate , biology , shrub , ecology , botany , soil science , geology , geotechnical engineering
Xylem water potential of the midelevation conifers Pinus jeffreyi, Pinus lambertiana, Abies concolor , and Calocedrus decurrens , the higher elevation Pinus monticola and Abies magnifica , and co‐occurring evergreen angiosperm shrubs, together with soil moisture under these plants, were monitored at three sites on the Kern Plateau in the southernmost Sierra Nevada Range of California. Site locations spanned the ecotone between the mid‐ and upper montane forests at elevations of 2230–2820 m. Measurements were made through a low‐snowfall year and a heavy‐snowfall year. In the Mediterranean climate of the Sierra Nevada, the heavy winter snowpack persists into late spring, after precipitation has effectively stopped. We found the subsequent depletion of soil moisture due to plant water uptake to result in predawn xylem water potentials for conifers more negative by 0.6–1.4 MPa than those for shrubs or inferred soil potentials. Shrubs generally depleted soil moisture more rapidly and ultimately extracted a greater fraction of the available soil moisture than did the conifers. This depletion of soil moisture by shrubs, particularly Arctostaphylos patula , may limit conifer growth and regeneration by prematurely terminating growth on the shallow soils studied. The conifers all generally showed similar patterns of soil moisture use, except that A. magnifica extracted moisture more rapidly early in the season.