Biomass estimation procedures in short rotation forestry

Biomass estimation procedures in short rotation forestry vary in their methodology, complexity and time demand depending on the specific aim of the estimation operation. In commercial short rotation forestry, estimates of harvestable biomass often are used to decide on harvest timing or continued management and to calculate economic gains under the actual market situation. For research purposes, weight estimates of single trees and their components are needed to describe and predict, e.g. leaf dynamics and the relative size differentiation that develops among individuals in a growing population. A biomass estimation procedure is defined as a planned chain of elements, integrated to comply with a specific aim. Elements such as defining a sampling unit, subsampling within primary units, model choice and conversions from single tree to stand area, fresh weight to dry weight and standing biomass to harvestable biomass, all may be included in a procedure. Those elements have to be modified according to the predefined aim and object of estimation. Consequently, a biomass estimation procedure is a compromise in which accuracy speed and knowledge of the underlying biological reality together determine the final shape of the procedure and its results. This paper provides a short overview of current biomass estimation methods and gives details about the major elements in the procedures, especially on regression methods. Recent developments in biomass estimation methodology are exemplified with analyses on short rotation forests and attention is paid to the need for standardisation and automatization of the procedures. (C) 1999 Elsevier Science B.V. All rights reserved.