A Generalized Methodology for Estimating Forest Ingrowth at Multiple Threshold Diameters

Bethesda

1993

S. 776-798

28 Lit. Ang.

Bandaufführung

64700

Ingrowth is defined as the number or volume of trees that periodically grow into the smallest measured size class of a forest stand. We present a model to predict the number of ingrowth trees at a variable threshold diameter for 6 forest vegetation types common to the central United States. The model is based on observations on 2,373 remeasured inventory plots from 8 sources in Missouri, Illinois, Indiana, and Ohio. The number of ingrowth trees decreases significantly with increasing threshold diameter. The concept of crown competition factor was used to set a biologically realistic upper limit on the number of ingrowth trees for any given threshold diameter. Number of ingrowth trees . acre-1 . decade-1 was predicted as a function of the maximum possible number of ingrowth trees and the threshold diameter. Fitted models were highly significant for all forest type, and the general shape of the response surface was biologically realistic. Precision of the estimates was low because ingrowth is a highly variable process.