Estimating root system biomass from breast-height diameters

Estimates of tree root system biomass are important to understanding the dynamics of forest systems and tree growth. The difficult and time-consuming extraction of woody roots is often a limiting factor when estimating the below-stump biomass. Regression equations of root system biomass on diameter at breast height derived from other studies might be useful for applications in forestry and as a simple input variable for growth models. Data for developing regression equations and, where possible, equations were taken from the recent literature for Picea abies, Pseudotsuga menziesii, Pinus sylvestris, Pinus radiata, Pinus taeda, Fagus sylvatica, Quercus ilex and Quercus douglasii. The equation for Quercus petraea was developed using data from European research projects.