Water use by Emory oak in southeastern Arizona: Estimation by sap-flow measurements

Abstract

Water use by mature and sprout (coppice) forms of Emory oak (Quercus emoryi) was estimated by the sap-flow method. Five standards and five coppice trees were sampled in an area that had been harvested for fuelwood and five mature trees were sampled in an uncut area. Differences were recognized between coppice and standards in the cut area and between coppice trees and mature trees from the uncut area. Regression equations were derived relating estimated annual water use to tree diameter, height, and crown measurements for both cut- and uncut-area trees. Seasonal water use by each tree form showed relationship to precipitation, but little relationship to temperature and relative humidity. Woodland density and tree size measurements facilitate extrapolation of water use from the 15 sampled trees to a per area basis. Water use was approximately 1900 cubic meters per hectare per year, based upon drc measurements, for the uncut area and 3168 cubic meters for the cut area. Estimated water use on a per unit area was approximately 1.67 times greater for the cut area than the uncut area.