Age–Growth Modeling

Abstract

Growth of an individual or group of organisms is defined as the change in dimensions over time. Growth rates vary between and within plant and animal species. They are generally influenced by both genetic and phenotypic factors, and may be negative or positive. Positive growth relates to increases in dimensions (weight, height, and number of component parts) over time, while negative or decay growth refers to the decline over time. Human interference, either intentionally or accidentally, environmental influences and management practices can substantially influence the growth forms and patterns of individuals and population. Age/growth functions constitute important analytical tools in the management of natural resources. These models are explicit expressions of both theory and empirical knowledge, and are useful for growth and yield prediction, computation of sustainable crop yields, and evaluation of alternative management strategies, among others. The approach to age/growth modeling may be based on either primary (single) unit or stand (aggregate of units). Irrespective of modeling philosophy, the goal is identification of the most parsimonious and biologically‐reasonable model that best describes the relationship between the response variable (which is a measure of growth) and time (age). Biologically reasonable models involve parameters to which meaningful interpretation may be assigned.