Height-to-Crown-Base

Stage (1973) static regression model for height to crown base (HCB) of lodgepole pine. Predicts HCB from tree height, stand density (CCF), elevation, relative tree size (DBH/RMSQD), and habitat type. Single explicit-algebraic equation: HCB = one_foot*(b0 + b1*HT_ft + b2*ln(CCF) + b3*EL_100ft + b4*DBH_in/RMSQD_in + HAB). All regression coefficients are in feet-space; result converted to meters. Migrated from Vegetation.jl@010c3774dc5646d81806c6119c8a029a70f6c9a0:src/stage_prognosis.jl:257.