Kim Randleff-Rasmussen

Forest Growth Simulation Using L-Systems

Abstract

This project creates a realistic model of forest development and growth. It models the trees in diagram

form using the wide-spread technique of L-Systems. The simulation of the forest growth takes into account

a number of important issues in ecosystem development including the addition of new trees to the

population, the removal of old trees and the changes that occur in existing trees due to interactions with

others.

The interactions aim to model the competition that occurs between individual trees within a forest for

the limited resources such as light, nutrients, water and CO2. The interactions are simulated by checking

for intersections between the circles which represent the space each tree takes up. When an intersection

is discovered, the stronger tree dominates the weaker and the latter begins to die. Plants also die when

they reach a maximum age.

Two particular tests were conducted on the system, one which checked for the realistic depiction

of the results of competition and another which compared the output to that of another forest simulator

(JABOWA III). The results of both tests were positive, prompting the conclusion that, though not realistic

in minute detail, this simulator produces a realistic and thus viable depiction of forest growth.