A flexible radial increment model for individual trees in pure even-aged stands

Abstract

To capture the common feature of various individual growth models for trees in pure and even-aged stands, a generic model with a form parameter according to each species is proposed. With a final objective of implementing this model into simulation software of silvicultural treatments, particular care was taken to structure the model for consistent behaviour outside the data fields of calibration and to limit the independent variables to those available to managers. The first analysis, using data from a young spruce stand, allowed introduction of simple variables (basal area and dominant height) to express competition effects. Then the model was fitted on a large data set to take into account silvicultural treatments and fertility conditions. Finally the model tested on spruce was directly adjusted for Douglas-fir and was found to be sufficiently flexible to describe growth of this species. This newly derived model is a relatively generic tool, which can be fitted for other species in regular stands.