A process-based model to evaluate site quality for Eucalyptus nitens in the Bio-Bio Region of Chile

Abstract

In a particular region, potential site productivity, expressed as wood production, is linearly related to leaf area index (LAI), a variable that expresses the amount of foliar surface available for photosynthesis ( Waring et al. , 2005 ). The maximum potential LAI on a given site in turn depends on the structural properties of particular tree species, climate and site resources ( Waring and Running, 1998 ). Potential productivity has been traditionally calculated by modelling height growth for a selected group (dominant height) of trees in the stand. This approximation, called site index, has at least three signifi cant limitations. First, it is based on a single variable that is not suffi cient to represent the stand ’ s real growth potential ( Bernier et al. , 2003 ). Second, it requires the presence of trees for measurement, which strongly limits its use in areas where trees of a given species have not been previously established ( Ford and Bassow, 1989 ). Third, it gives no direct information about LAI and consequently cannot be used to construct mechanistic models ( Ford and Bassow, 1989 ). Process-based models simulate productivity by directly modelling the effect of environmental factors on physiological processes (Landsberg and Gower, 1997). The 3-PG model developed by Landsberg and Waring (1997) is used in natural and planted forests in A process-based model to evaluate site quality for Eucalyptus nitens in the Bio-Bio Region of Chile