CASE STUDY: Old Field Succession Model

Source:

Swartzman, G.L. and S.P. Kaluzny: Ecological Simulation Primer, Macmillan, New York, 1987.

Background:

After farmland has been abandoned, various species of grass arrive to reclaim the land. Based on a study of 30 old fields in Oklahoma, a succession of five dominant or co-dominant grass species were identified. Helianthus annus (sunflower) and Digitaria sanguinalis identify the first stage, Aristida oligantha (three-awn grass) the second stage, Aristada basiramea (red three-awn) the third stage, Eragrostis secundiflora (lovegrass) the fourth stage and Andropogen scoparius (little bluestem) and Bouteloua curtipendula (sidecoats grama) the final, climax stage.

Modeling:

We wish to model the percent of area dominated by each type of grass for a period of 10 years. Initially, 85 percent of the field is in the first successional stage, 10 percent in the second stage, and 5 percent in the third stage. For each time step, the flow rate is as follows:

Developed by
Graphic of Shodor Logo

	From 1	From 2	From 3	From 4	From 5
To 1
To 2	0.8
To 3	0.2	1.0
To 4			0.7
To 5				0.8