Category Archives: abstract model

9.1 the difficulty of inferring process from pattern

This is an implementation of the model described in

Cale WG, Henebry GM and Yeakley JA 1989 Inferring process from pattern in natural communities. BioScience, 39, 600-605.

which demonstrates the challenges involved in inferring processes from patterns.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo to run this file.

5.21 Stark model of gullying

This model is an approximate implementation of the model described in

Stark CP 1994 Cluster growth modeling of plateau erosion. Journal of Geophysical Research, 99, 13957-13969.

which combines invasion percolation, diffusion-limited aggregation and Eden growth to simulated gullying erosion at a plateau edge.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo including the gradient extension to run this file.

5.19 the ‘sand-pile’ forest fire model

This model is an implementation of a simple forest fire model with a primary focus on the size distribution of the fires that are produced. It is based on the model described in

Bak P and Chen K 1990 A forest-fire model and some thoughts on turbulence. Physics Letters A, 147, 297–300.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo to run this file.

5.18 the SIMMAP neutral landscape model

This model implements the SIMMAP process for generation of neutral landscapes as described in

Saura S and Martinez-Milan J 2000 Landscape pattern simulation with a modified random clusters method. Landscape Ecology, 15, 661-677.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo to run this file.

This model also requires a text file to configure the relative proportions of each class of landscape that it will produce. This file should not be renamed, and should be placed in the same folder as the model file.

The first line of this file indicates the number of different landscape classes required. Subsequent lines indicate for each required class the desired relative proportion of the landscape that it should occupy. If the model’s percolation parameter is set too high, then it may be very difficult for the model to produce landscapes with proportions close to the requested levels.

5.16 diffusion-limited aggregation (DLA)

This is an implementation of an on-lattice (i.e. grid-based) diffusion-limited aggregation process. See

Witten TA and Sander LM 1981 Diffusion-limited aggregation, a kinetic critical phenomenon. Physical Review Letters, 47, 1400–1403.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo including the gradient extension to run this file.

5.14 Benguigui’s Eden process based model of urban growth

This model simulates a version of Benguigui’s highly abstract model of urban growth, as discussed in

Benguigui L 1995 A new aggregation model. Application to town growth. Physica A: Statistical Mechanics and its Applications, 219, 13–26.
Benguigui L 1998 Aggregation models for town growth. Philosophical Magazine Part B, 77, 1269–1275.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo including the gradient extension to run this file.

5.12 Eden growth along a linear invasion front

This model draws on ideas discussed in

Edwards SF and Wilkinson DR 1982 The surface statistics of a granular aggregate. Proceedings of the Royal Society of London. Series A, 381(1780), 17-31.

and allows you to explore the rate of progress made by an Eden invasion process advancing along a linear ‘front’.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo including the gradient extension to run this file.

5.11 the Williams-Bjerknes Eden growth process model for spread of ‘abnormal’ cells

This model is an implementation of the process described in

Williams T and Bjerknes R 1972 Stochastic model for abnormal clone spread through epithelial basal layer. Nature, 236, 19–21.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo including the gradient extension to run this file.