Stand-Damage & Gypsy Moth Life System

Stand-Damage Model

The Stand-Damage Model simulates tree diameter and height growth, foliage production, and mortality. Each year the model calculates diameter growth of trees as a function of relative stocking (a measure of tree crowding), shading, heat, and defoliation. Users describe a forest stand by entering tree counts by species and diameter class. Parameters for over sixty tree species are provided. The user can enter defoliation scenarios and silvicultural treatments.
For a Tree Growth Example, click here. For current literature, click here.

Stand-Damage Applet

To Run the latest version as a Java Applet (Stand-Damage Model with Java), click here.

Gypsy Moth Software

Two models describe the North American Gypsy Moth population dynamics. The Life System Model is the most complex. The simple model is the system of three coupled differential equations (Ordinary Differential Equations Model).

Gypsy Moth Life System Model (GMLSM)

The GMLSM simulates the gypsy moth population dynamics within a single forest stand over a defined time interval (years). It models the growth, feeding, and mortality of gypsy moth by following a number of cohorts on a degree-day basis. It also models the population dynamics of natural enemies, including predators, parasites, and pathogens affecting and affected by gypsy moth. Because foliage is growing at the same time that gypsy moth is feeding, foliage growth dynamics is represented on a tree species-specific basis. Default conditions are provided and the user can set up simulated management actions (including viral, bacterial, or chemical pesticides, mating disruption, sterile egg release, and/or stand manipulations). Model parameters can be adjusted to account for local conditions. The Stand-Damage Model is included in the GMLSM.

Ordinary Differential Equations Model

This model consists of three coupled ordinary differential equations: One represents gypsy moth, one represents forest stand foliage, and the third represents natural enemies. While it lacks the details of the GMLSM, it provids insights into the stability and asymptotic behavior of this three trophic-level system. It has been extended to a system of partial differential equations and used to examine dispersal questions on a local level. For literature information, click here.


GMPHEN predicts gypsy moth growth from egg eclosion to adult emergence from the pupal stage. In this DOS software, the user supplies weather site data in one of five formats. The software predicts instar distribution over time. For literature information, click here.

Gypsy Moth Life Systems    
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Updated: January 15, 2004 - George Racin