The total foliar area or mass of a tree is difficult to measure, as is
its bark or cambial area, and various other components of aboveground
biomass. A variety of sampling methods is proposed and estimators of
these characteristics are presented. Based on probability precepts, al
l estimators are unbiased. An unbiased estimator of variance for each
estimator also is presented. The basis in probability rather than a fi
tted regression equation provides some important safeguards, and is a
useful alternative when fitted regression functions are unavailable fo
r a particular species and physiographic condition.