A stand basal area model for plantation grown New Zealand kauri

The research covered in this paper is part of a program designed to establish the New Zealand kauri (Agathis australis (D.Don) Lindl.), as a short rotation crop of 80 years by determining optimum silvicultural strategies. Growth models are essential planning tools that aid the development of these strategies. This paper only covers the development of a stand basal area model responsive to thinning. The model was developed with all the available data from planting trials. The plantings trials were unrepresentative and from different localities, which meant different growth rates. The re-measurement data spanned short time periods and at different growth stages of kauri. Irregular measurements were characteristic of these short time periods. A state space model was identified with properties that exhibited stability and robustness in simulation analyses.