The Succession model

Download Model
Download the .scn, .sel and .lse files by clicking on the following link:

Note that this particular model can be found in the Succession folder under the SimpleFireModel file. For More information, please see SELES FireSuccession Lab Handout in the Handout folder.

Model Code Exploration
In the following sections we will examine all of the model files for this model. Note that instead of downloading the zip file above, you could just copy the text in the boxes below into a text editor and save it with the appropriate name (Section title). Opening the resulting .scn file in the SELES simulator would run this model.

Succession.scn
Scenario Information initialTimeSinceFire = ..\gisData\cell\initialTSF0 initialSpecies = ..\gisData\cell\initialSpecies0 Model Dimensions: initialSpecies SuccessionModel.sel

Succession.lse
LSEVENT: SimpleSuccession DEFINITIONS GLOBAL CONSTANT: MaxTSF GLOBAL VARIABLE: PatchBased,SProbAspen2Spruce, SProbPine, SProbPine2Spruce LAYER: TimeSinceFire, Species, Visited GLOBAL CONSTANT: rAspen, rPine, rSpruce, rBalsam CLUSTER VARIABLE: patchSpecies, patchTSF, newPatchSpecies ENDDEF // Succession is modelled every year RETURNTIME RETURNTIME = 365.25 Visited = 0 ENDRT PROBINIT TimeSinceFire = MIN(TimeSinceFire + 1, MaxTSF) // Only non-zero probabilities for aspen and pine PROBINIT = ((Species EQ rAspen) OR (Species EQ rPine)) AND (TimeSinceFire >= 100) // At the patch level: prefer to change pine to spruce or balsam (to create more contagious patches) // 50% chance of becoming spruce 50% chance of becoming balasm newPatchSpecies = CLASSIFY(Species) rAspen: IF UNIFORM(0,1) <= SProbAspen2Spruce THEN rSpruce // 10% chance for aspen ELSE rAspen rPine: IF UNIFORM(0,1) <= SProbPine // 1% chance for pine THEN IF UNIFORM(0,1) <= SProbPine2Spruce THEN rSpruce ELSE rBalsam ELSE rPine ENDFN // To identify patch patchSpecies = Species patchTSF = TimeSinceFire ENDPI TRANSITIONS IF (Visited EQ 0) Species = newPatchSpecies ENDFN TRANSITIONS = (PatchBased > 0) AND (Visited EQ 0) Visited = 1 ENDTR SPREADTIMESTEP = -2 // Spread to other cells in patch SPREADLOCATION REGION CENTRED(1,1.5,EUCLIDEAN) DECISION (Species EQ patchSpecies) AND (patchTSF EQ TimeSinceFire) ENDSL SPREADPROB = 1

Succession.sel
LSEVENT: SimpleAging DEFINITIONS GLOBAL CONSTANT: MaxTSF LAYER: TimeSinceFire ENDDEF // Succession is modelled every year RETURNTIME = 365.25 // Aging simply increments TSF by one year! TRANSITIONS TRANSITIONS = TRUE TimeSinceFire = MIN(TimeSinceFire + 1, MaxTSF) ENDTR

SuccessionModel.sel
Seles Model Information Time Units: Day Year 365.25 Landscape Events: Succession.lse Variable-Input View Maps: Species = initialSpecies TimeSinceFire = initialTimeSinceFire Variable-Output View Maps: Species TimeSinceFire Global Constants: MaxTSF = 200 rAspen = 1 rPine = 2 rSpruce = 3 rBalsam = 4 Output Model Bounds: TimeSinceFire: MaxTSF Species: 4 Global Variables: PatchBased = TRUE SProbAspen2Spruce = 0.1 SProbPine = 0.01 SProbPine2Spruce = 0.5 Output Frequency: 365.250000

Suggested Experiments
To explore this cellular automata model further, try the following: