Des modèles robustes et génériques de biomasse, exemple du hêtre

Abstract

This study describes an example of empirical biomass models devised for beech that meet the standards of exhaustiveness (branches and slender logging diameters included), performance (maximum accuracy of evaluation) and robustness (in respect of changes in productivity and silvicultural practises). This level of accuracy was achieved by adding stand age to the conventional explanatory variables in biomass models (diameter at 1.30 m and total tree height) and using a form of allometric equation that links the parameters in the model to the biological phenomena that govern tree growth. These models were applied to a chronosequence located in Brittany. The results obtained were compared to the Bouchon's volume tables (1982) currently in use by forest managers to estimate biomass stocks. It appears that tools currently being used on the ground significantly underestimate the stocks from the tree crowns which account for the largest source capable of satisfying wood energy needs. Concerning national carbon stock estimations, applying biomass equations increases their accuracy by 10% compared to first computing volume followed by mass.