Patterns of Water Use by Shrubs in Southern California

Author： Miller Philip C. Poole Dennis K.

Publisher： Society of American Foresters

ISSN： 0015-749X

Source： Forest Science, Vol.25, Iss.1, 1979-03, pp. : 84-98

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Abstract

The objectives of this study were to describe the seasonal and geographic patterns of soil moisture in southern California shrublands, to describe the seasonal progression and give current estimates of the annual water use by major shrub species, and to correlate the water use with structural characteristics of the species and the vegetation. Water use was estimated from the seasonal courses of soil moisture, xylem pressure potentials, leaf conductances to water loss, and water characteristics of the dominant species in coastal sage scrub and chaparral. Soil moisture was depleted by the end of the summer in both areas, but earlier in the coastal scrub than in the chaparral and earlier in mixed than in chamise chaparral. Similar patterns of water stress appeared in xylem pressure potentials and leaf conductances. Potentials in summer were lower in Artemisia californica, Arctostaphylos glauca, and Ceanothus greggii than in Adenostoma fasciculatum, and were consistently higher in Rhus ovata, R. laurina, and R. integrifolia. Maximum transpiration per m^-2 of leaf area was 0.7-2.0 mm day^-1 and 130-280 mm yr^-1, depending on species and site. The patterns of water use by shrubs correlate with structural characteristics of the species and the community. Forest Sci. 25:84-98.