GROWTH & YIELD MODEL
In recent decades, big-leaf mahogany (Swietenia macrophylla) has been intensively harvested across its natural range in tropical South America. Future timber production from natural forests will depend on the protection and stewardship of surviving commercial populations through sustainable management practices. The Growth & Yield Model presented here uses NetLogo 4.1.2 software to simulate population recovery and timber production of mahogany populations under study in the Brazilian Amazon since 1995.
To run the model under default conditions, press Defaults, then Setup, then Run 1 Year. Defaults restores default harvest and model parameters. Setup establishes the population on the landscape and Run 1 Year simulates the population for a single year. Press Run X Years to simulate the population until the time limit expires or all tree are harvested and or die. To simulate alternative management scenarios, adjust the harvest parameters accordingly.
Each year, the model grows, logs, kills, disturbs, and reproduces trees according to demographic parameters derived from annual field censuses of several thousand seedlings, saplings, and trees. Trees on the landscape are sized proportionate to diameter and will disappear/appear with mortality/reproduction. The red circles represent annual disturbances with the darker red representing the zone of recruitment for each disturbance.
For help during model simulations, press the ? buttons for definitions of the features within the adjacent section. Press All Definitions for a summary of all model features. Additionally, the Growth & Yield Model User Manual can be downloaded here and the model authors are available for support.
The Growth & Yield Model can be run on your computer by downloading the model, model software, and User Manual here. The computer version of the model allows you to upload your own population data, conduct simulation experiments, export simulation results, and simulate a greater variety of example populations.