Transpiration by dryland oaks: studies in the south-western United States and Northern Israel

Increased understanding of transpiration by dryland oaks in the woodlands of the southwestern United States and northern Israel has been obtained from studies in the two countries. Transpiration was estimated in both studies by the heat pulse velocity (HPV) method in stands of Quercus emoryi, a drought-deciduous species growing in the south-western United States, and stands supporting Q. ithaburensis, a deciduous oak, and Q. calliprinos, an evergreen oak, in northern Israel. Estimates of daily transpiration rates by individual trees and annual transpiration amounts on a stand basis indicate that depending on the species and stand structure, 45-80% of the precipitation inputs to the stands sampled are represented by transpiration component of the respective hydrologic cycles. (C) 2003 Elsevier Science Ltd. All rights reserved.