Many attributes of forest trees can be regarded as integrals of some c
ontinuous-dimensional characteristic, and thus their estimation is ame
nable to variance reduction sampling strategies that have been devised
and developed in the simulation field. For the estimation of tree cha
racteristics, these methods provide alternatives to the usual estimati
on by a fitted regression, and in addition, they provide a flexibility
to estimate the integral between any two heights on the tree bole. Th
e application of these methods to the estimation of bole surface area
and bark volume is explained, and practical aspects of implementation
are discussed.