created with NetLogo
view/download model file: invasive_plants.nlogo
Invasive species are non-native species that move into and disrupt native communities. Some, like Garlic Mustard, can produce a monoculture that crowds out other species. This simulation, based on a cell automata model, shows the role that disturbed areas can play in the distribution of an invasive plant.
Each patch looks at surrounding patches. If a patch is adjacent to enough invaded and/or disturbed patches, it will be invaded also. If it has few or no invaded or disturbed neighboring patches, it will be reclaimed by the native flora. The thresholds for these values are set with sliders. Roads represent disturbed areas which make it easier for an invasive species to gain a foothold.
First explore increasing the initial density of the invasive plant. Then add a network of roads and explore the effects of density.
This section could give some ideas of things for the user to notice while running the model.
Try increasing and decreasing the threshold values. The model is extremely sensitive to changes in these values.
Currently, the only mechanism for plants to spread is by being adjacent. This prevents the invasive species from spreading across roads, for example. In fact, most invasive species have extremely small seeds which are easily blown across roads. Add a mechanism for patches to expand to non-adjacent patches.
This model uses the same logic as the "Life" and "Traffic Grid" models in the Netlogo library.
This model was created as part of the 2008 BioQUEST Curriculum Consortium Summer Workshop.
Copyright 2008 by Steven Brewer. All rights reserved.
This model was inspired by many of the sample Netlogo models and parts
were based on functions from the "Life" and "Traffic Grid" models. (Wilensky, U. (2001). NetLogo Enzyme Kinetics model. http://ccl.northwestern.edu/netlogo/models/EnzymeKinetics. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.)
Permission to use, modify or redistribute this model is hereby granted, provided that both of the following requirements are followed:
a) this copyright notice is included.
b) this model will not be redistributed for profit without permission
from the authors.
Contact the authors for appropriate licenses for redistribution for profit.
To refer to this model in academic publications, please use:
Brewer, S.D. (2008). Invasive Plants and Disturbance. http://bcrc.bio.umass.edu/netlogo/models/InvasivePlants Biology Computer Resource Center
In other publications, please use:
Copyright 2008 by Steven Brewer. All rights reserved. See http://bcrc.bio.umass.edu/netlogo/models/InvasivePlants for terms of use.