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 descr ibing and interpreting survival-type data. The Weibull model and some of it s key features are briefly reviewed. The process and advantages of incorpor ating the Weibull distribution in ecological models are illustrated by comp aring efforts to describe the foliar biomass dynamics of young, open-grown, Scots pine as functions of branch length and age. These dynamics are model led on a biological foundation by assuming foliage production depends allom etrically on branch length and that foliage survival on a branch follows an age-dependent Weibull distribution. Like previously developed polynomial-t ype models, the Weibull-based model described the data well. In contrast to these polynomial models, however, the Weibull-based model produced biologi cally meaningful parameter estimates as well as plausible predicted trends when applied near the edges of the data set and beyond. (C) 2001 Elsevier S cience B.V. All rights reserved.