Ground-truth verification of relations between forest basal area and certain ecophysiographic factors using a geographic information system

A geographic information system (GIS) was used to relate measured basal area and cartographically derived ecophysiographic variables in an effort to produce locally reliable estimates of basal area over a forest rather than at individual point locations. The best regression model produced a relatively low R2 of 0.50 and a root mean square error (RMSE) of 7.3 m2 per ha. Moreover, the independent variables of this model were terrain-based data—not cartographic information. Thus this model is incapable of producing basal area estimates for all locations in a forest. It is concluded that, because a considerable amount of work needs to be conducted in a number of disciplines before such a model can improve significantly, the approach adopted will not be a viable alternative for producing locally reliable information for a number of years. This work has wider implications as it demonstrates that, while GIS technology has the capability to apply a statistical model to a spatial framework, the results will not necessarily reflect local ground conditions with precision.