WATER RELATIONS OF TWO CALIFORNIA CHAPARRAL SHRUBS

Water use patterns of two California chaparral shrub species, chamise (Adenostoma fasciculatum H. and A.) and Stanford manzanita (Arctostaphylos stanfordiana Parry), were compared during summer drought. Observations of diurnal and seasonal courses of shoot water potential, leaf conductance and transpiration revealed that chamise was more conservative in water use than manzanita. Evidence obtained cast doubt on a hypothesis previously proposed to explain an anomalous pattern of shoot water potential in chamise.