Estimating Leaf Area of Big Sagebrush from Measurement of Sapwood

Abstract

Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis) plants were destructively sampled in May 1984 in southeast Oregon to examine the applicability of the pipe model theory to an arid land shrub. This theory proposes that total leaf area or leaf biomass of a plant is limited by the amount of conducting tissue available to service the leaves. Basal sapwood areas were measured for 20 Wyoming big sagebrush plants and correlated with the biomass and leaf area of the supported foliage. Additional samples of leaves were collected over a 12-month period to evaluate fluctuations in leaf weight to leaf area relationships. Basal sapwood area of sagebrush stems was a reliable indicator of foliage biomass or leaf area (r2=0.95). Leaf area to weight relationships fluctuated significantly throughout the year with the most substantial changes occurring during the growing season. Although this species is an evergreen, the dynamic nature of foliage production and morphology demands intensive seasonal sampling to accurately predict leaf areas.