Abstract

Digital images of poplar canopies in the Bay of Plenty and East Coast were captured to develop a model to predict canopy closure in poplar stands as a function of basal area. A model to predict basal area as a function of site quality, age, and stocking was also estimated. The effect of canopy closure on relative understorey pasture production in poplar stands was investigated using existing data sources. It was concluded that a simple linear function was unlikely to adequately model this relationship, and a more complex function was consequently estimated. The equations to predict basal area, canopy closure, and understorey pasture production can be used in conjunction with data describing initial livestock-carrying capacity and the seasonal distribution of pasture growth, to predict the effect of site, age, and stocking on understorey livestock-carrying capacity in poplar stands.