Applicability of Stand Structural Characteristics to Stemflow Modeling

Abstract

AbstractA stemflow (SF) estimation model, based on the correlation between coefficients (a and b) of the regression equation (SF= aPg − b, where Pg is gross rainfall) obtained from sample tree and their diameter at breast height (DBH), is presented. Estimation by the model for SF from two deciduous broad-leaved forests shows favorable agreement with the measurement. Once the equations for regression coefficients are determined, the model has the potential to easily estimate SF from an entire stand through sampling of some representative trees. However, the model is site-specific. In order to mitigate the weakness of this model, the combination of previous results provided generalized equations for the coefficients. The generalized equation adequately estimated SF of some forests while its estimation was biased for other forests, which indicates that SF variation between forests is closely related to structural differences. Actually, the SF frequency distribution of two forest stands was significantly different. So, influence of structural factors on SF was also studied using funneling ratio (FR) that integrates the efficiency of trunk and canopy characteristics to SF. Comparison of FR showed that SF was significantly correlated to crown-projection area (CPA) and basal area at breast height (BA). Parameters (β1 and β2) within the model were significantly correlated to respective stand density and leaf area index (LAI).Key words: DBHdeciduous broad-leaved forestfunneling ratioregression coefficientstemflow estimation model