Forest Dynamic Model - Dewdney (2000)

extensions [table]
globals [i1 k1 x-cor y-cor local-richness-counts local-richness hist-frq-local rel-hist-frq-local sp n n2 time-spent specs time-spent-list abundance-list mean-time-spent data mean-life-comm k2 i2 h num j2 j s1]
breed [trees a-tree]
trees-own [species time-system]

to setup
  clear-all
  resize-world 0 (w2 - 1) 0 (w1 - 1)
  set JL (w1 + 1) * (w2 + 1)
  set k1 -1
  set n 2
  set sp 0
  set j 0
  set S w2
  set mean-time-spent []
  set abundance-list []
  set data []
  set mean-life-comm []
    while [k1 < w1 - 1 ] [
      set k1 k1 + 1
      set i1 -1
      while [i1 < w2 - 1] [
        set i1 i1 + 1
        create-trees 1 [
          setxy i1 k1
          set time-system 0
          set species random S
          set shape "circle"
        ]
      ]
    ]

  set local-richness-counts map count table:values table:group-agents trees [species]
  set local-richness length local-richness-counts
  set hist-frq-local sort-by > map count table:values table:group-agents trees [species]
  set rel-hist-frq-local map [i -> i / JL] hist-frq-local
  reset-ticks
end 

to go
  ingest-process
  reproduce-process
  set local-richness-counts map count table:values table:group-agents trees [species]
  set local-richness length local-richness-counts
  set hist-frq-local sort-by > map count table:values table:group-agents trees [species]
  set rel-hist-frq-local map [i -> i / JL] hist-frq-local
  tick
end 

to ingest-process
  if-else (extinction? = true)[
  ask one-of trees [
    set x-cor xcor
    set y-cor ycor
    die]
  ]
  [rare-species-protect]
end 

to reproduce-process
  ask one-of trees [
    hatch 1 [
      set xcor x-cor
      set ycor y-cor
      set time-system 0
    ]
  ]
end 

to rare-species-protect
  ask one-of trees [
    set sp species
    set n count trees with [species = sp]
  ]

  if-else (n > 1) [
    ask one-of trees with [species = sp] [
      set x-cor xcor
      set y-cor ycor
      die
    ]
  ]
  [rare-species-protect]
end