;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; ;; Fire in the forest model written by Byron Roland, George Kampis and Istvan Karsai, 2011-2016 ;; The result of this model has been published in Ecological Complexity 28 (2016): 12-23. ;;Please cite this Netlogo model as: ;;Roland, B., Kampis, G. and Karsai, I (2016): Fire in the forest. Netlogo v. 5.3.1 simulation. ;;http://ccl.northwestern.edu/netlogo/models/community/Fire%in%the%forest ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; globals[i m seed] ;;Variables used as counters for the year and the excel file number extension breed[animals animal] breed[fires fire] breed[trees tree] breed[animalcorpses animalcorpse] ;;Used to count the number of dead animals breed[treecorpses treecorpse] ;;Count the dead trees breed[firecorpses firecorpse] ;;Count the dead fires to Setup ;;Initializes the program. ;; (for this model to work with NetLogo's new plotting features, ;; __clear-all-and-reset-ticks should be replaced with clear-all at ;; the beginning of your setup procedure and reset-ticks at the end ;; of the procedure.) __clear-all-and-reset-ticks set seed random 10000 random-seed seed create-animals NumberofAnimals[ set color brown ;;Initializes the starting number of set shape "sheep 2" ;;organisms and their shape and color setxy random-xcor random-ycor] create-trees NumberofTrees[ set color green set shape "tree" setxy random-xcor random-ycor] create-fires FireStrength [ set color red set shape "fire" setxy random-xcor random-ycor] update-plot end to Go ;;Coninuous loop that updates the deathplot ifelse i >= YearsPerSetup ;;and asks the organisms to do specific [stop] ;;things defined below this method [update-deathplot ;;Continues until variable i has been incremented ask animals[ ;;to a value greater than the parameter YearsPerSetup move-animal] ask fires[ kill-trees kill-animals] update-plot tick end-year] end to update-deathplot set-current-plot "Dead Populations" ;;Updates the plot of dead animals and trees. set-current-plot-pen "Burned Animals" plot count animalcorpses set-current-plot-pen "Burned Trees" plot count treecorpses end to move-animal repeat AnimalMovementSpeed[ ifelse any? fires in-radius 1 ;;Look for fires, if there are any [die] ;;within 1 block then die. [rt random 360 fd 1]] ;;Animals move randomly as many times as AnimalMovementSpeed end to kill-trees let kill one-of trees in-radius 1 ifelse kill != nobody ;;If theres a tree in the fires path, kill [face kill ask kill [set breed treecorpses hide-turtle] fd 1 ;;it and hatch 1 more fire. hatch 1 [rt random 360 fd 1]] [set breed firecorpses hide-turtle] ;;Otherwise die end to kill-animals repeat (count animals in-radius 1) ;;Kills all animals in radius 1 [let kill one-of animals in-radius 1 if kill != nobody ;;If theres a animal in the fires path, kill [face kill ask kill [set breed animalcorpses hide-turtle] fd 1]] ;;it and then check for trees end to update-plot set-current-plot "Populations" ;;Updates the animal, tree, fire population graph. set-current-plot-pen "animals" ;;this is done every tick so as to keep a coninuous plot count animals ;;look and feel in the graph set-current-plot-pen "trees" plot count trees set-current-plot-pen "fires" plot count fires end to end-year if ticks > 11 [ask animals[ death-animal reproduce-animal] create-trees count trees * TreeBreedingPercent / 100[ ;;Create 10 percent of the current number set color green ;;of trees and hatch them randomly. set shape "tree" setxy random-xcor random-ycor if any? other trees-on patch-ahead 0 [die]] ;;If trees on the same patch, die. create-fires FireStrength [ ;;Create a given number of fires set color red ;;based of fire strength parameter set shape "fire" setxy random-xcor random-ycor] ask animalcorpses[ ;;kills all the corpses so as to reset die] ;;the number of dead "turtles" back to 0 ask treecorpses[ die] ask firecorpses[ die] set i i + 1 reset-ticks] end to death-animal if AnimalTreeDDDeath? ;;If animals can die from lack of trees [if not any? trees in-radius 1 [die]] ;;If there are no trees within 1 block, die. ifelse count trees in-radius 1 < 5 [if random 50 < AnimalDeathPercent [die]] ;;If there are less than 5 trees within [if random 100 < AnimalDeathPercent [die]] ;;1 block then animal death rate is doubled. end to reproduce-animal ifelse count trees in-radius 2 < AnimalTreeVariableBreeding ;;If there are 5 trees within two blocks [stop] ;;of the animal, hatch 1 new animal. [ifelse count animals in-radius 2 > AnimalAnimalVariableBreeding ;;If there are more than 5 animals around [stop] ; ;two blocks dont hatch 1. [hatch 1 [rt random 360 fd 1]]] end to basic-simulation ;;Creates a basic simulation set AnimalTreeDDDeath? false ;;used to make life easier set NumberofAnimals 100 ;;by just having to press one button set NumberofTrees 500 ;;rather than trying to find the set YearsPerSetup 100 ;;right values for each parameter set AnimalTreeVariableBreeding 5 ;;to create a stable ecosystem set AnimalAnimalVariableBreeding 5 set TreeBreedingPercent 10 set AnimalMovementSpeed 5 set AnimalDeathPercent 10 set FireStrength 0 end @#$#@#$#@ GRAPHICS-WINDOW 681 23 1178 541 19 19 12.5122 1 10 1 1 1 0 1 1 1 -19 19 -19 19 0 0 1 Month 30.0 SLIDER 8 52 283 85 NumberofAnimals NumberofAnimals 0 2000 100 10 1 NIL HORIZONTAL SLIDER 8 91 282 124 NumberofTrees NumberofTrees 0 1000 500 10 1 NIL HORIZONTAL BUTTON 9 10 108 43 Setup setup NIL 1 T OBSERVER NIL NIL NIL NIL 1 BUTTON 116 10 211 43 Go go T 1 T OBSERVER NIL NIL NIL NIL 1 MONITOR 17 262 94 307 Animals count animals\n 17 1 11 MONITOR 102 262 180 307 Trees count trees 17 1 11 MONITOR 189 261 267 306 Fires count fires 17 1 11 PLOT 12 331 291 571 Populations Time(Months) Populations 0.0 0.0 0.0 750.0 true true "" "" PENS "Animals" 1.0 0 -6459832 true "" "" "Trees" 1.0 0 -10899396 true "" "" "Fires" 1.0 0 -2674135 true "" "" SLIDER 353 162 501 195 AnimalMovementSpeed AnimalMovementSpeed 0 10 5 1 1 NIL HORIZONTAL SLIDER 353 201 531 234 AnimalDeathPercent AnimalDeathPercent 0 100 10 1 1 % HORIZONTAL SWITCH 351 69 523 102 AnimalTreeDDDeath? AnimalTreeDDDeath? 1 1 -1000 SLIDER 8 130 126 163 YearsPerSetup YearsPerSetup 0 100 100 1 1 NIL HORIZONTAL SLIDER 352 275 556 308 AnimalTreeVariableBreeding AnimalTreeVariableBreeding 0 10 5 1 1 NIL HORIZONTAL SLIDER 352 238 558 271 AnimalAnimalVariableBreeding AnimalAnimalVariableBreeding 0 10 5 1 1 NIL HORIZONTAL SLIDER 351 110 516 143 TreeBreedingPercent TreeBreedingPercent 0 100 10 5 1 % HORIZONTAL PLOT 330 332 620 571 Dead Populations Time(Months) Dead Populations 0.0 0.0 0.0 150.0 true true "" "" PENS "Burned Animals" 1.0 0 -16777216 true "" "" "Burned Trees" 1.0 0 -955883 true "" "" MONITOR 16 209 88 254 Year i 17 1 11 BUTTON 137 130 255 163 Basic Simulation basic-simulation NIL 1 T OBSERVER NIL NIL NIL NIL 1 TEXTBOX 317 10 467 28 Fire 12 0.0 1 TEXTBOX 314 52 464 70 Trees 12 0.0 1 TEXTBOX 312 144 462 162 Animals 12 0.0 1 TEXTBOX 562 278 676 318 Animal breeding variable based on number of trees present. 11 0.0 1 TEXTBOX 563 233 673 273 Animal breeding variable based on number of animals around. 11 0.0 1 TEXTBOX 537 66 669 114 Are the animals dependent on the trees to survive? 11 0.0 1 SLIDER 352 15 524 48 FireStrength FireStrength 0 20 2 1 1 NIL HORIZONTAL @#$#@#$#@ ## WHAT IS IT? This model explores the dynamics of an animal/tree/fire ecosystem with random fires. The result of this model has been published in Ecological Complexity 28 (2016): 12-23. Abstract: Our model considers a new element in forest fire modeling, namely the dynamics of a forest animal, intimately linked to the trees. We show that animals and trees react differently to different types of fire. A high probability of fire initiation results in several small fires, which do not allow for a large fuel accumulation and thus the destruction of many trees by fire, but is found to be generally devastating to the animal population at the same time. On the other hand, a low fire initiation probability allows for the accumulation of higher quantities of fuel, which in turn results in larger fires, more devastating to the trees than to the animals. Thus, we suggest that optimal fire management should take into account the relation between fire initiation and its different effects on animals and trees. Further, wildfires are often considered as prime examples for power-law-like frequency distributions, yet there is no agreement on the mechanisms responsible for the observed patterns. Our model suggests that instead of a single unified distribution, a superposition of at least two different distributions can be detected and this suggests multiform mechanisms acting on different scales. None of the discovered distributions are compatible with a power-law hypothesis. Please cite this Netlogo model as: Roland, B., Kampis, G. and Karsai, I (2016): Fire in the forest. Netlogo v. 5.3.1 simulation. http://ccl.northwestern.edu/netlogo/models/community/Fire%in%the%forest ## HOW IT WORKS The model has three hierarchical levels: entities, interactions, and environment, with the first two being modeled explicitly and the environment being modeled implicitly. Populations are characterized by the census of each organism type at the end of a given year. The number of burned trees and animals are counted every year. The model is spatially explicit. Trees are immobile, while animals and fires can move, following explicit rules. The state of the agents is tracked through time and defined by the location of each individual and each interaction between individuals and the environment. The population's dynamics and individual behaviors emerge from the interactions at the individual (agent) level. All sensing and interaction are strictly local to the agents. Individuals "know" (access) their own current activity status (i.e., this status is explicitly represented in a state variable) and they can check (i.e., sense) the existence and the status of other agents in the neighborhood. Things to Know ******************** The unit of time is 1 tick = 1 month (12 months is a year). Animals can breed, whereby one individual becomes 2 individuals: - There must be enough trees around (AnimalTreeVariableBreeding). - There must NOT be more than a certain number of other animals around (AnimalAnimalVariableBreeding). Animals die by: - Old age (AnimalDeathPercent). - Tree Density dependent death rate (AnimalTreeDDDeath). - Fire burns. Trees produce seeds: - Some percent of the total current population (TreeBreedingPercent). - A tree only develops if the seend falls into a tree-less spot. Trees die by: - Fire burn. Fires are initiated: - Random location. - FireStrength describes the maximum number of fire initiation point/year. - If there is a tree in the adjacent neighborhood, the fire can spread to that neighborhood. Fires kill: -Trees. -Animals. Fires die if: -There are no more live trees to burn in the adjacent neighborhood. ## HOW TO USE IT 1.) Initialize the number of animals, trees, and fires. 2.) Adjust the slider parameters (see below), or use the default settings. 3.) Press the SETUP button. 4.) Press the GO button to begin the simulation. 5.) Look at the main monitor to watch the ecosystem develop. 6.) Look at the POPULATIONS plot to watch the populations fluctuate over time. 7.) Look at the DEAD POPULATIONS plot to watch the number of animals and trees that die. Parameters *************** NumberofAnimals: The initial number of animals. NumberofTrees: The initial number of trees. YearsPerSetup: The number of years per setup run. FireStrength: The maximum number of fires created each year. AnimalTreeDDDeath: Density dependent death of animals based on the trees. TreeBreedingPercent: The percentage of trees that breed every year. AnimalMovementSpeed: The number of times a animal moves per month (1 tick). AnimalDeathPercent: The percent of animals that will die each year due to old age. AnimalAnimalVariableBreeding: Number of animals around an animal that limits its breeding (birth rate depend on animal density). AnimalTreeVariableBreeding: The number of trees needed for an animal to breed. ## THINGS TO NOTICE Small fire strength will produce a small number of devastating large fires. This is very detrimental to the trees. Large fire strength produces many smaller and medium sized fires. This is more devastatiung to the animal populations than to the trees. The distribution of fires DOES NOT follow a power law (see paper for detailed analysis). ## THINGS TO TRY Try changing the TreeBreedingPercent and FireStrength parameters. Notice the significant changes in the population graph. Try finding specific parameters to create a stable ecosystem between the three "breeds" such that none of them become extinct. The fire strength parameter corresponds to the number of lightning that can initiate fires in the forest. ## EXTENDING THE MODEL Add extra parameters such as estimating wind speed and direction as well as temperature and movement patterns of the animals, or add the possibility of the animals moving towards the trees rather than moving randomly looking for an appropriate breeding habitat. ## NETLOGO FEATURES Note the use of breeds to model three different kinds of "turtles": animals, trees, and fires. Note the use of "if random 100 < AnimalDeathPercent" to determine the percent of animals that die each year. Also note the random fire strength to signify a random number of fires in a range between the user defined maximal amount and 0. This is much more realistic than a rigidly deterministic number of fires each year. ## RELATED MODELS Look at "Wolf Sheep Predation" for another model of ecosystem dynamics involving three elements. Also see different forest fire models in the community page, but those mainly focus on 2 components only. ## CREDITS AND REFERENCES Roland, Byron roland@goldmail.etsu.edu ETSU BISC Johnson City TN USA Kampis, George kampis.george@gmail.com German Research Center for Artificial Intelligence (DFKI GmbH) Karsai, Istvan karsai@etsu.edu ETSU BISC Johnson City TN USA Paper based on this program: Karsai, I., Roland, B. and Kampis, G. 2016: The effect of fire on an abstract forest ecosystem: An agent based study. 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