Estimating stem profile using canopy metrics : a forest inventory application for airborne remote sensing

The precision of plot based inventories is limited by the spatial variability of forest metrics. This thesis develops an inventory method for the assessment of radiata pine (Pinus radiata D. Don) plantations that exhibit high spatial variability. The method utilises forest canopy metrics that may be acquired using airborne remote sensing technologies in the estimation of individual tree stem profile properties. A review of the growth behaviour of radiata pine isolates the period prior to significant silvicultural interventions as the optimum sampling age. A review of recent developments in remote sensing technologies isolates tree location and height as the best potential sampling covariates. Tree height, location and stem profile data in two age cohorts are drawn from a single radiata pine estate in southeastern Tasmania, Australia. Local density indices are derived using tree height and location data and their utility for predicting breast height diameter is evaluated. Segmented and variable-form stem profile models employing individual tree height and local density are then derived using mixed and generalized leastsquares modelling methodologies in order to facilitate estimation of merchantable timber volume. It is shown that neighbour tree location, distance and height with respect to a subject tree, are all significant breast height diameter predictors. Their influence is attributed to the asymmetric and one-sided nature of the interactions between trees during stand development. The stem profile models are shown to provide merchantable volume estimates with acceptable bias, with simple segmented models preferred for their parsimony. Mixed modelling methods are shown to best describe the variance-covariance structure of the stem profile data, with some attendant advantages in model predictive behaviour. The evaluation shows that remote sensing products may be used for plantation inventory in many radiata pine stands.