The Weibull model and an ecological application: describing the dynamics of foliage biomass on Scots pine

The Weibull formulation provides a concise but flexible framework for describing and interpreting survival-type data. The Weibull model and some of its key features are briefly reviewed. The process and advantages of incorporating the Weibull distribution in ecological models are illustrated by comparing efforts to describe the foliar biomass dynamics of young, open-grown, Scots pine as functions of branch length and age. These dynamics are modelled on a biological foundation by assuming foliage production depends allometrically on branch length and that foliage survival on a branch follows an age-dependent Weibull distribution. Like previously developed polynomial-type models, the Weibull-based model described the data well. In contrast to these polynomial models, however, the Weibull-based model produced biologically meaningful parameter estimates as well as plausible predicted trends when applied near the edges of the data set and beyond.