ROMFARMS

;; This  model accompanies Joyce, J. forthcoming, Modelling agricultural strategies in the Dutch Roman limes zone via agent-based modelling (ROMFARMS). Springer (Basel)
;; and Joyce, J. forthcoming, Farming along the limes. Using agent-based modelling to investigate possibilities for subsistence and surplus-based agricultural production in the Lower Rhine delta between 12BC and 270AD, PhD thesis, Vrije Universiteit Amsterdam.

extensions [ gis ]

breed [ settlements settlement ]

breed [ persons person ]

breed [ animals animal ]

globals [
  raster
  settlement-density
  area
  d-pop
  d1-pop
  elderly-male-list
  elderly-female-list
  adult-male-list
  adult-female-list
  male-4th-list
  female-4th-list
  male-3rd-list
  female-3rd-list
  male-2nd-list
  female-2nd-list
  male-1st-list
  female-1st-list
  count-children-list
  pop-growth
  calories-in-crops
  fallow-time
  basic-yield
  sowing-rate
  yield-increase-manure
  N-content-manure
  sowing-time
  ploughing-time
  manuring-time
  harvesting-time
  ploughing-labour-list
  total-ploughing-labour-list
  sowing-labour-list
  total-sowing-labour-list
  manuring-labour-list
  total-manuring-labour-list
  harvesting-labour-list
  total-harvesting-labour-list
  min-arable-land-list
  arable-land-list
  yield-list
  surplus-list
  grain-deficit-list
  count-famines
  cattle-meat-list
  cattle-milk-list
  cattle-manure-list
  sheep-meat-list
  sheep-milk-list
  sheep-wool-list
  horse-surplus-list
  meadow-land-list
  pasture-land-list
  fodder-collection-time
  total-fodder-labour-list
  fodder-labour-list
  horse-pop-list
  cattle-pop-list
  sheep-pop-list
  d-pop-cattle
  d1-pop-cattle
  d-pop-horse
  d1-pop-horse
  d-pop-sheep
  d1-pop-sheep
  pop-growth-sheep
  pop-growth-cattle
  pop-growth-horse
  adult-weight-cattle
  immature-weight-cattle
  young-weight-cattle
  adult-weight-sheep
  immature-weight-sheep
  young-weight-sheep
  %-edible-carcass-cattle
  %-edible-carcass-sheep
  milk-yield-cattle
  milk-yield-sheep
  lactation-length-cattle
  lactation-length-sheep
  wool-yield-sheep
  manure-daily-yield
  twinning-rate-sheep
  alphaS
  alphaC
  alphaH
  alpha
  neonatal-mortality-sheep
  neonatal-mortality-cattle
  neonatal-mortality-horse
  annual-mortality-rate
  CYMR
  CIMR
  CAMR
  SYMR
  SIMR
  SAMR
  HIMR
  fodder-sheep
  fodder-cattle
  fodder-horse
  pasture-land-sheep
  pasture-land-cattle
  pasture-land-horse
  yield-grassland
  walking-speed
  max-load-adult-male
  max-load-adult-female
  max-load-other
  fuel-collection-time
  timber-collection-time
  fuel-workforce-list
  total-fuel-labour-list
  fuel-labour-list
  fuel-deficit-list
  distance-travelled-fuel-list
  construction-labour-list
  construction-workforce-list
  timber-deficit-list
  distance-travelled-construction-list
  biomass-list
  biomass-forest-list
  catchment-area
]

patches-own [
  raster-value
  patch-owner
  landscape-type
  use
  biomass
  countdown-fallow
  countdown-reforest
]

settlements-own [
  no-households
  age
  people
  livestock
  catchment
  calories-required
  min-grain-store
  ploughing-labour-1
  ploughing-labour-2
  sowing-labour-1
  sowing-labour-2
  manuring-labour-1
  manuring-labour-2
  harvesting-labour-1
  harvesting-labour-2
  grain-store
  max-arable-land-land
  max-arable-land-grain
  max-arable-land-labour
  min-arable-land
  arable-land
  yield-grain
  surplus-grain
  grain-deficit
  SNM
  CNM
  SYM
  CYM
  SIM
  CIM
  SAM
  CAM
  cattle-meat-yield
  sheep-meat-yield
  cattle-milk-yield
  sheep-milk-yield
  sheep-wool-yield
  cattle-manure-yield
  horse-surplus
  pasture-land
  meadow-land
  fodder-labour-1
  fodder-labour-2
  fuel-workforce
  fuel-store
  fuel-target
  fuel-requirement
  fuel-labour-1
  fuel-labour-2
  construction-requirement
  construction-store
  construction-target
  construction-workforce
  construction-labour
]

persons-own [
  sex
  age
  my-spouse
  my-house
  distance-travelled-fuel
  distance-travelled-construction
  count-children
  mortality
  fertility
  load
  max-load
  processing-time-fuel
  processing-time-timber
]

animals-own [
  age
  sex
  species
  fertility
  survivorship
  my-owner
  lactating
]

to setup
  ca
  setup-landscape
  setup-globals
  setup-agents
  reset-ticks
end 

to go
  if ticks = runtime[
    stop
  ]
  if not any? settlements [
    stop
  ]
  go-demography
  go-arable
  go-pastoral
  go-fuel
  go-construction
  update-globals
  update-patches
  ask settlements [
    ifelse age = reconstruction-frequency [
      set age 0
    ]
    [
      set age age + 1
    ]
  ]
  tick
end 

to setup-landscape ;; sub-process generates landscape within which agents interact. Landscapes can be randomly-generated ("hyp") or reconstructed from palaeogeographic data (1-32).
   if region = "hyp" [
    resize-world -16 16 -16 16
    set-patch-size 13
    if area-levee > 0 [
      ask one-of patches [
        set pcolor brown
        set landscape-type "levee"
      ]
      while [ count patches with [ pcolor = brown ] < ( count patches * area-levee ) ] [
        ask one-of patches with [ pcolor = brown ] [
          if any? neighbors with [ pcolor != brown ] [
            ask one-of neighbors with [ pcolor != brown ] [
              set pcolor brown
              set landscape-type "levee"
            ]
          ]
        ]
      ]
    ]
    if area-floodbasin > 0 [
      while [ count patches with [ pcolor = green ] < ( count patches * area-floodbasin ) and any? patches with [ pcolor = brown and any? neighbors with [ pcolor != brown and pcolor != green ] ] ] [
        ask one-of patches with [ pcolor = brown ] [
          if any? neighbors with [ pcolor != brown and pcolor != green ] [
            ask one-of neighbors with [ pcolor != brown and pcolor != green ] [
              set pcolor green
              set landscape-type "floodbasin"
            ]
          ]
        ]
      ]
      while [ count patches with [ pcolor = green ] < ( count patches * area-floodbasin ) and count patches with [ pcolor = black ] > 0 ] [
        ask one-of patches with [ pcolor = green ] [
          if any? neighbors with [ pcolor != brown and pcolor != green ] [
            ask one-of neighbors with [ pcolor != green and pcolor != brown ] [
              set pcolor green
              set landscape-type "floodbasin"
            ]
          ]
        ]
      ]
    ]
    ask patches [
      set raster-value "null"
    ]
  ]
  ask patches [
    set raster-value "null"
  ]
  if region != "hyp" [ ;; if a reconstructed landscaped is simulate, sub-process loads the relevant raster file and assigns a settlement density value depending on period to be simulated.
    gis:load-coordinate-system "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/UTM_zone31N.prj"
    resize-world -50 50 -50 50
    set-patch-size 5
    if region = 1 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_1.asc"
      if period = "IJZ" [
        set settlement-density 0.0141
      ]
      if period = "ROMVA" [
        set settlement-density 0.0212
      ]
      if period = "ROMVB" [
        set settlement-density 0.0226
      ]
      if period = "ROMMA" [
        set settlement-density 0.0268
      ]
      if period = "ROMMB" [
        set settlement-density 0.0254
      ]
    ]
    if region = 2 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_2.asc"
      if period = "IJZ" [
        set settlement-density 0.0034
      ]
      if period = "ROMVA" [
        set settlement-density 0.0127
      ]
      if period = "ROMVB" [
        set settlement-density 0.0127
      ]
      if period = "ROMMA" [
        set settlement-density 0.0141
      ]
      if period = "ROMMB" [
        set settlement-density 0.0141
      ]
    ]
    if region = 3 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_3.asc"
      if period = "IJZ" [
        set settlement-density 0
      ]
      if period = "ROMVA" [
        set settlement-density 0
      ]
      if period = "ROMVB" [
        set settlement-density 0.0035
      ]
      if period = "ROMMA" [
        set settlement-density 0.0035
      ]
      if period = "ROMMB" [
        set settlement-density 0.0035
      ]
    ]
    if region = 4 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_4.asc"
      if period = "IJZ" [
        set settlement-density 0
      ]
      if period = "ROMVA" [
        set settlement-density 0
      ]
      if period = "ROMVB" [
        set settlement-density 0
      ]
      if period = "ROMMA" [
        set settlement-density 0
      ]
      if period = "ROMMB" [
        set settlement-density 0.003
      ]
    ]
    if region = 5 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_5.asc"
      if period = "IJZ" [
        set settlement-density 0.0075
      ]
      if period = "ROMVA" [
        set settlement-density 0.0114
      ]
      if period = "ROMVB" [
        set settlement-density 0.0122
      ]
      if period = "ROMMA" [
        set settlement-density 0.0114
      ]
      if period = "ROMMB" [
        set settlement-density 0.0107
      ]
    ]
    if region = 6 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_6.asc"
      if period = "IJZ" [
        set settlement-density 0.007
      ]
      if period = "ROMVA" [
        set settlement-density 0.0106
      ]
      if period = "ROMVB" [
        set settlement-density 0.0106
      ]
      if period = "ROMMA" [
        set settlement-density 0.013
      ]
      if period = "ROMMB" [
        set settlement-density 0.0127
      ]
    ]
    if region = 7 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_7.asc"
      if period = "IJZ" [
        set settlement-density 0.0083
      ]
      if period = "ROMVA" [
        set settlement-density 0.0147
      ]
      if period = "ROMVB" [
        set settlement-density 0.0147
      ]
      if period = "ROMMA" [
        set settlement-density 0.019
      ]
      if period = "ROMMB" [
        set settlement-density 0.019
      ]
    ]
    if region = 8 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_8.asc"
      if period = "IJZ" [
        set settlement-density 0.0016
      ]
      if period = "ROMVA" [
        set settlement-density 0.0063
      ]
      if period = "ROMVB" [
        set settlement-density 0.0067
      ]
      if period = "ROMMA" [
        set settlement-density 0.0129
      ]
      if period = "ROMMB" [
        set settlement-density 0.0129
      ]
    ]
    if region = 9 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_9.asc"
      if period = "IJZ" [
        set settlement-density 0.0059
      ]
      if period = "ROMVA" [
        set settlement-density 0.0148
      ]
      if period = "ROMVB" [
        set settlement-density 0.0148
      ]
      if period = "ROMMA" [
        set settlement-density 0.0207
      ]
      if period = "ROMMB" [
        set settlement-density 0.0207
      ]
    ]
    if region = 10 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_10.asc"
      if period = "IJZ" [
        set settlement-density 0.0041
      ]
      if period = "ROMVA" [
        set settlement-density 0.0068
      ]
      if period = "ROMVB" [
        set settlement-density 0.0068
      ]
      if period = "ROMMA" [
        set settlement-density 0.0084
      ]
      if period = "ROMMB" [
        set settlement-density 0.0084
      ]
    ]
    if region = 11 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_11.asc"
      if period = "IJZ" [
        set settlement-density 0.0064
      ]
      if period = "ROMVA" [
        set settlement-density 0.0142
      ]
      if period = "ROMVB" [
        set settlement-density 0.0144
      ]
      if period = "ROMMA" [
        set settlement-density 0.0187
      ]
      if period = "ROMMB" [
        set settlement-density 0.0187
      ]
    ]
    if region = 12 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_12.asc"
      if period = "IJZ" [
        set settlement-density 0.0046
      ]
      if period = "ROMVA" [
        set settlement-density 0.0082
      ]
      if period = "ROMVB" [
        set settlement-density 0.0082
      ]
      if period = "ROMMA" [
        set settlement-density 0.0115
      ]
      if period = "ROMMB" [
        set settlement-density 0.0115
      ]
    ]
    if region = 13 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_13.asc"
      if period = "IJZ" [
        set settlement-density 0.0038
      ]
      if period = "ROMVA" [
        set settlement-density 0.0064
      ]
      if period = "ROMVB" [
        set settlement-density 0.0066
      ]
      if period = "ROMMA" [
        set settlement-density 0.0064
      ]
      if period = "ROMMB" [
        set settlement-density 0.0062
      ]
    ]
    if region = 14 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_14.asc"
            if period = "IJZ" [
        set settlement-density 0.0057
      ]
      if period = "ROMVA" [
        set settlement-density 0.0068
      ]
      if period = "ROMVB" [
        set settlement-density 0.0068
      ]
      if period = "ROMMA" [
        set settlement-density 0.0075
      ]
      if period = "ROMMB" [
        set settlement-density 0.007
      ]
    ]
    if region = 15 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_15.asc"
      if period = "IJZ" [
        set settlement-density 0.0065
      ]
      if period = "ROMVA" [
        set settlement-density 0.0092
      ]
      if period = "ROMVB" [
        set settlement-density 0.0092
      ]
      if period = "ROMMA" [
        set settlement-density 0.0097
      ]
      if period = "ROMMB" [
        set settlement-density 0.0099
      ]
    ]
    if region = 16 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_16.asc"
      if period = "IJZ" [
        set settlement-density 0.0034
      ]
      if period = "ROMVA" [
        set settlement-density 0.0041
      ]
      if period = "ROMVB" [
        set settlement-density 0.0043
      ]
      if period = "ROMMA" [
        set settlement-density 0.0041
      ]
      if period = "ROMMB" [
        set settlement-density 0.0041
      ]
    ]
    if region = 17 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_17.asc"
      if period = "IJZ" [
        set settlement-density 0.0026
      ]
      if period = "ROMVA" [
        set settlement-density 0.0031
      ]
      if period = "ROMVB" [
        set settlement-density 0.0031
      ]
      if period = "ROMMA" [
        set settlement-density 0.0034
      ]
      if period = "ROMMB" [
        set settlement-density 0.0034
      ]
    ]
    if region = 18 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_18.asc"
      if period = "IJZ" [
        set settlement-density 0.0044
      ]
      if period = "ROMVA" [
        set settlement-density 0.0208
      ]
      if period = "ROMVB" [
        set settlement-density 0.0295
      ]
      if period = "ROMMA" [
        set settlement-density 0.0438
      ]
      if period = "ROMMB" [
        set settlement-density 0.0416
      ]
    ]
    if region = 19 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_19.asc"
      if period = "IJZ" [
        set settlement-density 0.0047
      ]
      if period = "ROMVA" [
        set settlement-density 0.0117
      ]
      if period = "ROMVB" [
        set settlement-density 0.0117
      ]
      if period = "ROMMA" [
        set settlement-density 0.0152
      ]
      if period = "ROMMB" [
        set settlement-density 0.0187
      ]
    ]
    if region = 20 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_20.asc"
      if period = "IJZ" [
        set settlement-density 0.0037
      ]
      if period = "ROMVA" [
        set settlement-density 0.0064
      ]
      if period = "ROMVB" [
        set settlement-density 0.0092
      ]
      if period = "ROMMA" [
        set settlement-density 0.0147
      ]
      if period = "ROMMB" [
        set settlement-density 0.0175
      ]
    ]
    if region = 21 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_21.asc"
      if period = "IJZ" [
        set settlement-density 0.0085
      ]
      if period = "ROMVA" [
        set settlement-density 0.0318
      ]
      if period = "ROMVB" [
        set settlement-density 0.0318
      ]
      if period = "ROMMA" [
        set settlement-density 0.0425
      ]
      if period = "ROMMB" [
        set settlement-density 0.0361
      ]
    ]
    if region = 22 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_22.asc"
      if period = "IJZ" [
        set settlement-density 0
      ]
      if period = "ROMVA" [
        set settlement-density 0.0031
      ]
      if period = "ROMVB" [
        set settlement-density 0.0031
      ]
      if period = "ROMMA" [
        set settlement-density 0.0031
      ]
      if period = "ROMMB" [
        set settlement-density 0.0031
      ]
    ]
    if region = 23 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_23.asc"
      if period = "IJZ" [
        set settlement-density 0.0048
      ]
      if period = "ROMVA" [
        set settlement-density 0.0061
      ]
      if period = "ROMVB" [
        set settlement-density 0.0061
      ]
      if period = "ROMMA" [
        set settlement-density 0.0145
      ]
      if period = "ROMMB" [
        set settlement-density 0.0145
      ]
    ]
    if region = 24 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_24.asc"
      if period = "IJZ" [
        set settlement-density 0
      ]
      if period = "ROMVA" [
        set settlement-density 0
      ]
      if period = "ROMVB" [
        set settlement-density 0
      ]
      if period = "ROMMA" [
        set settlement-density 0.0063
      ]
      if period = "ROMMB" [
        set settlement-density 0.0063
      ]
    ]
    if region = 25 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_25.asc"
      if period = "IJZ" [
        set settlement-density 0
      ]
      if period = "ROMVA" [
        set settlement-density 0.0047
      ]
      if period = "ROMVB" [
        set settlement-density 0.0047
      ]
      if period = "ROMMA" [
        set settlement-density 0.0047
      ]
      if period = "ROMMB" [
        set settlement-density 0.0047
      ]
    ]
    if region = 26 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_26.asc"
      if period = "IJZ" [
        set settlement-density 0.0019
      ]
      if period = "ROMVA" [
        set settlement-density 0.0033
      ]
      if period = "ROMVB" [
        set settlement-density 0.0033
      ]
      if period = "ROMMA" [
        set settlement-density 0.009
      ]
      if period = "ROMMB" [
        set settlement-density 0.0095
      ]
    ]
    if region = 27 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_27.asc"
      if period = "IJZ" [
        set settlement-density 0.0047
      ]
      if period = "ROMVA" [
        set settlement-density 0.0093
      ]
      if period = "ROMVB" [
        set settlement-density 0.0093
      ]
      if period = "ROMMA" [
        set settlement-density 0.0114
      ]
      if period = "ROMMB" [
        set settlement-density 0.0114
      ]
    ]
    if region = 28 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_28.asc"
      if period = "IJZ" [
        set settlement-density 0.0017
      ]
      if period = "ROMVA" [
        set settlement-density 0.0067
      ]
      if period = "ROMVB" [
        set settlement-density 0.0071
      ]
      if period = "ROMMA" [
        set settlement-density 0.0067
      ]
      if period = "ROMMB" [
        set settlement-density 0.0067
      ]
    ]
    if region = 29 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_29.asc"
      if period = "IJZ" [
        set settlement-density 0.0083
      ]
      if period = "ROMVA" [
        set settlement-density 0.01
      ]
      if period = "ROMVB" [
        set settlement-density 0.0102
      ]
      if period = "ROMMA" [
        set settlement-density 0.0105
      ]
      if period = "ROMMB" [
        set settlement-density 0.01
      ]
    ]
    if region = 30 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_30.asc"
      if period = "IJZ" [
        set settlement-density 0.0095
      ]
      if period = "ROMVA" [
        set settlement-density 0.0102
      ]
      if period = "ROMVB" [
        set settlement-density 0.0102
      ]
      if period = "ROMMA" [
        set settlement-density 0.01
      ]
      if period = "ROMMB" [
        set settlement-density 0.01
      ]
    ]
    if region = 31 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_31.asc"
      if period = "IJZ" [
        set settlement-density 0.0165
      ]
      if period = "ROMVA" [
        set settlement-density 0.0225
      ]
      if period = "ROMVB" [
        set settlement-density 0.024
      ]
      if period = "ROMMA" [
        set settlement-density 0.0262
      ]
      if period = "ROMMB" [
        set settlement-density 0.0255
      ]
    ]
    if region = 32 [
      set raster gis:load-dataset "C:/Users/jamaa/Documents/USB 10072017/Palaeogeography/clip_32.asc"
      if period = "IJZ" [
        set settlement-density 0.0162
      ]
      if period = "ROMVA" [
        set settlement-density 0.0324
      ]
      if period = "ROMVB" [
        set settlement-density 0.0324
      ]
      if period = "ROMMA" [
        set settlement-density 0.0306
      ]
      if period = "ROMMB" [
        set settlement-density 0.0288
      ]
    ]
    gis:set-world-envelope-ds gis:envelope-of raster
    gis:apply-raster raster raster-value
  ]
  ask patches [
    if raster-value = 1 or raster-value = 4 or raster-value = 7 or raster-value = 9 [ ;; ROMFARMS sets different colours for different reconstructed landscape elements but only assigns values to levees and floodbasins.
      set landscape-type "levee"
      set pcolor brown
    ]
    if raster-value = 11 or raster-value = 12 [
      set pcolor green
      set landscape-type "floodbasin"
    ]
    if raster-value = 24 or raster-value = 0 or raster-value = 33 [
      set pcolor blue
    ]
    if raster-value = 14 or raster-value = 15 or raster-value = 17  [
      set pcolor 12
    ]
    if raster-value = 25 or raster-value = 28 or raster-value = 21  [
      set pcolor 125
    ]
    if raster-value = 20 or raster-value = 32 or raster-value = 31 [
      set pcolor 47
    ]
    set patch-owner nobody
    set use "none"
  ]
  setup-forest
end 

to setup-globals ;; assigns values to the numerous variables used in ROMFARMS and sets the initial values for list variables.
  ask settlements [
    set elderly-male-list lput count people with [ sex = "male" and age >= 50 ] elderly-male-list
    set elderly-female-list lput count people with [ sex = "female" and age >= 50 ] elderly-female-list
    set adult-male-list lput count people with [ sex = "male" and age >= 16 and age < 50 ] adult-male-list
    set adult-female-list lput count people with [ sex = "female" and age >= 16 and age < 50 ] adult-female-list
    set male-4th-list lput count people with [ sex = "male" and age >= 10 and age < 16 ] male-4th-list
    set female-4th-list lput count people with [ sex = "female" and age >= 10 and age < 16 ] female-4th-list
    set male-3rd-list lput count people with [ sex = "male" and age >= 5 and age < 10 ] male-3rd-list
    set female-3rd-list lput count people with [ sex = "female" and age >= 5 and age < 10 ] female-3rd-list
    set male-2nd-list lput count people with [ sex = "male" and age >= 1 and age < 5 ] male-2nd-list
    set female-2nd-list lput count people with [ sex = "female" and age >= 1 and age < 5 ] female-2nd-list
    set male-1st-list lput count people with [ sex = "male" and age < 1 ] male-1st-list
    set female-1st-list lput count people with [ sex = "female" and age < 1 ] female-1st-list
  ]
  set calories-in-crops 3100 ;; kCal/kg
  set basic-yield 1000 ;; kg/ha
  set sowing-rate 200 ;; kg/ha
  set yield-increase-manure 15 ;; kg per 1kg N
  set N-content-manure 0.006 ;; 6kg per ton manure
  set sowing-time 3 ;;hrs/ha
  set ploughing-time 30 ;; hrs/ha
  set manuring-time 30 ;; hrs/ha
  set harvesting-time 24 ;; hrs/ha
  set adult-weight-cattle 200 ;; kg per head
  set immature-weight-cattle 150 ;; kg per head
  set young-weight-cattle 35 ;; kg per head
  set adult-weight-sheep 25 ;; kg per head
  set immature-weight-sheep 18.75 ;; kg per head
  set young-weight-sheep 10 ;; kg per head
  set %-edible-carcass-cattle 0.6 ;; % of live weight
  set %-edible-carcass-sheep 0.3 ;; % of live weight
  set milk-yield-cattle 1.2 ;; litres per day
  set milk-yield-sheep 0.2 ;; litres per day
  set lactation-length-cattle 200 ;; days
  set lactation-length-sheep 135 ;; days
  set wool-yield-sheep 2 ;; kg per head
  set manure-daily-yield 0.06 ;; % of live weight per days
  set twinning-rate-sheep 0.2 ;; % probability of adult sheep producing two offspring
  set alphaS 7.5 ;; maximum age sheep - standard deviation
  set alphaC 17.5 ;; maximum age cattle - standard deviation
  set alphaH 27.5 ;; maximum age horse - standard deviation
  set alpha 2.5 ;; standard deviation (see above)
  set neonatal-mortality-sheep 0.32 ;; % probability of neonatal sheep dying from natural causes
  set neonatal-mortality-cattle 0.2 ;; % probability of neonatal cattle dying from natural causes
  set neonatal-mortality-horse 0.2 ;; % probability of neonatal horse dying from natural causes
  set annual-mortality-rate 0.014 ;; % probability of all animals to die per year
  set fodder-sheep 252 ;; kg/adult head for four months
  set fodder-cattle 756 ;; kg/adult head for four months
  set fodder-horse 756 ;; kg/adult head for four months
  set fodder-collection-time 16 ;; hrs/ha
  set pasture-land-sheep 9 ;; no. heads/ha
  set pasture-land-cattle 3 ;; no. heads/ha
  set pasture-land-horse 3 ;; no.heads/ha
  set yield-grassland 3000 ;; kg/ha
  set walking-speed 5 ;; km/hr
  set max-load-adult-male 30 ;; kg of firewood
  set max-load-adult-female 20 ;; kg of firewood
  set max-load-other 15 ;; kg of firewood
  set fuel-collection-time 3 ;; hrs/trip
  set timber-collection-time 6 ;; hrs/trip
  set biomass-forest-list [ ]
  set biomass-list [ ]
  ask patches with [ use = "forest" or use = "coppice" ] [
    set biomass-forest-list lput biomass biomass-forest-list
  ]
  ask patches with [ use = "forest" or use = "coppice" or use = "alt-wood" ] [
    set biomass-list lput biomass biomass-list
  ]
  set catchment-area 1
end 

to setup-agents ;;  sub-process generates settlement agents and places them randomly in the landscape on a levee patch. The number of agents generated depends on the values for the relevant interface parameters.
  set-default-shape settlements "house"
  while [ count settlements with [ no-households = 1 ] < no-1-household-settlements and any? patches with [ landscape-type = "levee" and use = "none" and count turtles-on neighbors = 0 ] ] [
    ask one-of patches with [ landscape-type = "levee" and use = "none" and count turtles-on neighbors = 0 ] [
      sprout 1 [
        set breed settlements
        set age 0
        set no-households 1
        set size 1
        set color white
        set people turtle-set [ ]
        set livestock turtle-set [ ]
        ]
      ]
    ]
  while [ count settlements with [ no-households = 2 ] < no-2-household-settlements and any? patches with [ landscape-type = "levee" and use = "none" and count turtles-on neighbors = 0 ] ] [
    ask one-of patches with [ landscape-type = "levee" and use = "none" and count turtles-on neighbors = 0 ] [
      sprout 1 [
        set breed settlements
        set age 0
        set no-households 2
        set size 1.25
        set color white
        set people turtle-set [ ]
        set livestock turtle-set [ ]
      ]
    ]
  ]
  while [ count settlements with [ no-households = 3 ] < no-3-household-settlements and any? patches with [ landscape-type = "levee" and use = "none" and count turtles-on neighbors = 0 ] ] [
    ask one-of patches with [ landscape-type = "levee" and use = "none" and count turtles-on neighbors = 0 ] [
      sprout 1 [
        set breed settlements
        set age 0
        set no-households 3
        set size 1.5
        set color white
        set people turtle-set [ ]
        set livestock turtle-set [ ]
      ]
    ]
  ]
  while [ count settlements with [ no-households = 5 ] < no-5-household-settlements and any? patches with [ landscape-type = "levee" and use = "none" and count turtles-on neighbors = 0 ] ] [
    ask one-of patches with [ landscape-type = "levee" and use = "none" and count turtles-on neighbors = 0 ] [
      sprout 1 [
        set breed settlements
        set age 0
        set no-households 5
        set size 1.75
        set color white
        set people turtle-set [ ]
        set livestock turtle-set [ ]
      ]
    ]
  ]
  ask settlements [
    repeat no-households [
      hatch 1 [ ;; produces one male adult per household and sets initial variables
        ht
        set breed persons
        set sex "male"
        set my-spouse nobody
        set age 16
        set distance-travelled-fuel 0
        set distance-travelled-construction 0
        set my-house myself
        ask my-house [
          set people ( turtle-set people myself )
        ]
      ]
      hatch 1 [
        ht ;; produces one female adult per household and sets initial variables
        set breed persons
        set sex "female"
        set my-spouse nobody
        set age 16
        set distance-travelled-fuel 0
        set distance-travelled-construction 0
        set count-children 0
        set my-house myself
        ask my-house [
          set people ( turtle-set people myself )
        ]
        set my-spouse one-of other persons with [ sex = "male" and age >= 16 and age < 50 and my-spouse = nobody and my-house = [ my-house ] of myself ] ;; sets spouse as one of other adults with opposite sex in the same settlement
        ask my-spouse [
          set my-spouse myself
        ]
      ]
      repeat 4 [
        hatch 1 [ ;; produces four sub-adults per household, ages set randomly between 0 and 15
          ht
          set breed persons
          set sex one-of ( list "male" "female" )
          set age 0 + random 15
          set distance-travelled-fuel 0
          set distance-travelled-construction 0
          set my-spouse nobody
          set my-house myself
          ask my-house [
            set people ( turtle-set people myself )
          ]
        ]
      ]
    ]
    config-settlements
  ]
end 

to go-demography
  set elderly-male-list [ ]
  set elderly-female-list [ ]
  set adult-male-list [ ]
  set adult-female-list [ ]
  set male-4th-list [ ]
  set female-4th-list [ ]
  set male-3rd-list [ ]
  set female-3rd-list [ ]
  set male-2nd-list [ ]
  set female-2nd-list [ ]
  set male-1st-list [ ]
  set female-1st-list [ ]
  set count-children-list [ ]
  set d1-pop d-pop
  update-settlements-1
  births
  deaths
  marriages
  ask settlements [
    set elderly-male-list lput count people with [ sex = "male" and age >= 50 ] elderly-male-list
    set elderly-female-list lput count people with [ sex = "female" and age >= 50 ] elderly-female-list
    set adult-male-list lput count people with [ sex = "male" and age >= 16 and age < 50 ] adult-male-list
    set adult-female-list lput count people with [ sex = "female" and age >= 16 and age < 50 ] adult-female-list
    set male-4th-list lput count people with [ sex = "male" and age >= 10 and age < 16 ] male-4th-list
    set female-4th-list lput count people with [ sex = "female" and age >= 10 and age < 16 ] female-4th-list
    set male-3rd-list lput count people with [ sex = "male" and age >= 5 and age < 10 ] male-3rd-list
    set female-3rd-list lput count people with [ sex = "female" and age >= 5 and age < 10 ] female-3rd-list
    set male-2nd-list lput count people with [ sex = "male" and age >= 1 and age < 5 ] male-2nd-list
    set female-2nd-list lput count people with [ sex = "female" and age >= 1 and age < 5 ] female-2nd-list
    set male-1st-list lput count people with [ sex = "male" and age < 1 ] male-1st-list
    set female-1st-list lput count people with [ sex = "female" and age < 1 ] female-1st-list
  ]
  ask persons [
    set age age + 1 ;; increases the age of all surviving inhabitants by one year
  ]
  update-settlements-2
end 

to go-arable
  set arable-land-list [ ]
  set min-arable-land-list []
  set yield-list [ ]
  set surplus-list [ ]
  set grain-deficit-list [ ]
  set sowing-labour-list [ ]
  set total-sowing-labour-list [ ]
  set ploughing-labour-list [ ]
  set total-ploughing-labour-list [ ]
  set manuring-labour-list [ ]
  set total-manuring-labour-list [ ]
  set harvesting-labour-list [ ]
  set total-harvesting-labour-list [ ]
  ifelse strategy-arable = "none" or strategy-arable = "extensification" [
    set fallow-time 2
  ]
  [
    set fallow-time 0
  ]
  calculate-land-arable
  calculate-yield-arable
  calculate-surplus-arable
end 

to go-pastoral
  ask animals [
    set age age + 1
  ]
  set d1-pop-horse d-pop-horse
  set d1-pop-cattle d-pop-cattle
  set d1-pop-sheep d-pop-sheep
  set sheep-pop-list [ ]
  set cattle-pop-list [ ]
  set horse-pop-list [ ]
  set sheep-meat-list [ ]
  set cattle-meat-list [ ]
  set sheep-milk-list [ ]
  set cattle-milk-list [ ]
  set sheep-wool-list [ ]
  set cattle-manure-list [ ]
  set horse-surplus-list [ ]
  set meadow-land-list [ ]
  set pasture-land-list [ ]
  set total-fodder-labour-list [ ]
  set fodder-labour-list [ ]
  set-mortality-rates
  births-animals
  natural-mortality
  slaughter
end 

to go-fuel
  ask persons [ ;; assigns the value for the maximum carrying load per person depending on age.
    if age >= 10 and age < 16 [
      set max-load max-load-other
    ]
    if age >= 16 and age < 50 and sex = "male" [
      set max-load max-load-adult-male
    ]
    if age >= 16 and age < 50 and sex = "female" [
      set max-load max-load-adult-female
    ]
    if age >= 50 [
      set max-load max-load-other
    ]
  ]
  set fuel-workforce-list [ ]
  set total-fuel-labour-list [ ]
  set fuel-labour-list [ ]
  set fuel-deficit-list [ ]
  set distance-travelled-fuel-list [ ]
  ask persons [
    set processing-time-fuel 0
    set distance-travelled-fuel 0
  ]
  calc-workforce-fuel
end 

to go-construction
  set construction-labour-list [ ]
  set construction-workforce-list []
  set timber-deficit-list [ ]
  set distance-travelled-construction-list [ ]
  ask persons [
    set processing-time-timber 0
    set distance-travelled-construction 0
  ]
  calc-workforce-construction
end 

to update-globals
  set d-pop count persons
  set d-pop-horse count animals with [ species = "horse" ]
  set d-pop-sheep count animals with [ species = "sheep" ]
  set d-pop-cattle count animals with [ species = "cattle" ]
  if ticks > 1 [ ;; calculates herd population growth as the percentage increase or decrease from the previous year
    set pop-growth ( d-pop - d1-pop ) / d1-pop
    if sheep? = TRUE [
      set pop-growth-sheep ( d-pop-sheep - d1-pop-sheep ) / d1-pop-sheep
    ]
    if cattle? = TRUE [
      set pop-growth-cattle ( ( d-pop-cattle - d1-pop-cattle ) / d1-pop-cattle )
    ]
    if horse? = TRUE [
      set pop-growth-horse ( d-pop-horse - d1-pop-horse ) / d1-pop-horse
    ]
  ]
  ask settlements [ ;; updates the values for the various labour expenditures and yields of grain and animal products.
    set arable-land-list lput arable-land arable-land-list
    set yield-list lput yield-grain yield-list
    set surplus-list lput surplus-grain surplus-list
    set grain-deficit-list lput grain-deficit grain-deficit-list
    set total-sowing-labour-list lput sowing-labour-1 total-sowing-labour-list
    set sowing-labour-list lput sowing-labour-2 sowing-labour-list
    set total-ploughing-labour-list lput ploughing-labour-1 total-ploughing-labour-list
    set ploughing-labour-list lput ploughing-labour-2 ploughing-labour-list
    if strategy-arable = "intensification" [
      set total-manuring-labour-list lput manuring-labour-1 total-manuring-labour-list
      set manuring-labour-list lput manuring-labour-2 manuring-labour-list
    ]
    set total-harvesting-labour-list lput harvesting-labour-1 total-harvesting-labour-list
    set harvesting-labour-list lput harvesting-labour-2 harvesting-labour-list
    set sheep-pop-list lput count livestock with [ species = "sheep" ] sheep-pop-list
    set cattle-pop-list lput count livestock with [ species = "cattle" ] cattle-pop-list
    set horse-pop-list lput count livestock with [ species = "horse" ] horse-pop-list
    set sheep-meat-list lput sheep-meat-yield sheep-meat-list
    set cattle-meat-list lput cattle-meat-yield cattle-meat-list
    set sheep-milk-list lput sheep-milk-yield sheep-milk-list
    set cattle-milk-list lput cattle-milk-yield cattle-milk-list
    set sheep-wool-list lput sheep-wool-yield sheep-wool-list
    set cattle-manure-list lput cattle-manure-yield cattle-manure-list
    set horse-surplus-list lput horse-surplus horse-surplus-list
    set meadow-land-list lput meadow-land meadow-land-list
    set pasture-land-list lput pasture-land pasture-land-list
    set total-fodder-labour-list lput fodder-labour-1 total-fodder-labour-list
    set fodder-labour-list lput fodder-labour-2 fodder-labour-list
    set total-fuel-labour-list lput fuel-labour-1 total-fuel-labour-list
    set fuel-labour-list lput fuel-labour-2 fuel-labour-list
    set construction-labour-list lput construction-labour construction-labour-list
    if fuel-requirement > fuel-store [
      set fuel-deficit-list lput ( fuel-requirement - fuel-store ) fuel-deficit-list
    ]
    if construction-requirement > construction-store and age = reconstruction-frequency [
      set timber-deficit-list lput ( construction-requirement - construction-store ) timber-deficit-list
    ]
  ]
  ask persons with [ distance-travelled-fuel > 0 ] [
    set distance-travelled-fuel-list lput distance-travelled-fuel distance-travelled-fuel-list
  ]
  ask persons with [ sex = "female" and age >= 16 ] [
    set count-children-list lput count-children count-children-list
  ]
  set biomass-list [ ]
  set biomass-forest-list [ ]
  ask patches with [ use = "forest" or use = "coppice" or use = "alt-wood" ] [
    set biomass-list lput biomass biomass-list
    if use = "forest" or use = "coppice" [
      set biomass-forest-list lput biomass biomass-forest-list
    ]
  ]
end 

to update-patches
  ask patches with [ countdown-reforest > 0 ] [ ;; time to regeneration of deforested patches reduced by 1 and if it reaches 0, patches regenerate
    set countdown-reforest countdown-reforest - 1
    if countdown-reforest = 0 [
      if landscape-type = "levee" and use = "forest" [
        set biomass ( 100 + random 20 ) * 439
      ]
      if landscape-type = "floodbasin" and use = "forest" [
        set biomass ( 110 + random 30 ) * 439
      ]
      if landscape-type = "fen" [
        set biomass ( 65 + random 20 ) * 439
      ]
      if use = "coppice" [
        set biomass ( 180 + random 40 ) * 439
      ]
    ]
  ]
  ask patches with [ landscape-type = "levee" and countdown-fallow > 0 ] [ ;; time for patches to be reused as arable land reduced by 1 and restores arable land to available to use when this value reaches 0.
    set countdown-fallow countdown-fallow - 1
    if countdown-fallow = 0 [
      set pcolor brown
    ]
  ]
  ask patches with [ biomass > 0 ] [
    set pcolor scale-color green biomass 100000 1000
  ]
end 

to births
  set-fertility
  ask persons with [ my-spouse != nobody and sex = "female" and age >= 16 and age < 50 ] [
    if random-float 1.0 < fertility [ ;; generates a random value lfrom 0 to 1. If the number is less than the fertility rate assigned to each married woman between 16 and 49 one child is generated. The sex of the child is assigned randomly.
      hatch 1 [
        set breed persons
        set age 0
        set sex one-of ( list "male" "female" )
        set my-house [ my-house ] of myself
        set my-spouse nobody
        set distance-travelled-fuel 0
        set distance-travelled-construction 0
      ]
      set count-children count-children + 1
    ]
  ]
end 

to deaths
  set-mortality
  ask persons [
    if random-float 1.0 < mortality [ ;; generates a random value from 0 to 1. If the number is less than the mortality rate assigned to each person, the person dies and is removed from the simulation.
      die
    ]
  ]
end 

to marriages
  ask persons with [ sex = "male" and age >= 16 and age < 50 and my-spouse = nobody ] [ ;; if a male aged 16 to 49 is unmarried, they will seek a new spouse. If no unmarried females between 16 and 49 are available, the sub-process ends.
    if any? other persons with [ sex = "female" and age >= 16 and age < 50 and my-spouse = nobody and my-house != [ my-house ] of myself ] [
      ifelse [ count people with [ my-spouse != nobody ] ] of my-house < ( [ no-households ] of my-house * 2 ) [ ;; if there is space for the new couple, the couple move to the male spouse's settlement. If not, the new couple moves to the female spouse's settlement.
        set my-spouse one-of other persons with [ sex = "female" and age >= 16 and age < 50 and my-spouse = nobody and my-house != [ my-house ] of myself ]
        ask my-spouse [
          set my-spouse myself
          set my-house [ my-house ] of myself
        ]
      ]
      [
        set my-spouse one-of other persons with [ sex = "female" and age >= 16 and age < 50 and my-spouse = nobody and my-house != [ my-house ] of myself ]
        ask my-spouse [
          set my-spouse myself
        ]
        new-settlement ;; if no space in either of the new spouse's original settlements, the sub-process for creation of a new settlement is called.
      ]
    ]
  ]
end 

to update-settlements-1 ;; updates the value for the calories required for the new population of each settlement once births, marriages and deaths have taken place.
  ask settlements [
    ifelse grain-store >= ( ( calories-required * %-calories-from-crops ) / calories-in-crops ) [
      set grain-store grain-store - ( ( calories-required * %-calories-from-crops ) / calories-in-crops )
    ]
    [
      set grain-deficit  ( ( ( calories-required * %-calories-from-crops ) / calories-in-crops ) - grain-store )
      set grain-store 0
    ]
    set calories-required ( count people with [ age >= 16 and age < 50 and sex = "male" ] * 3250 * 365 + count people with [ age >= 16 and age < 50 and sex = "male" ] * 550 * 6 * 7 ) ;; calculates total annual calories required by inhabitants of settlement
    set calories-required calories-required + ( count people with [ age > 50 and sex = "male" ] * 2650 * 365 )
    set calories-required calories-required + ( count people with [ age >= 16 and age < 50 and sex = "female" ] * 2800 * 365 + count people with [ age >= 16 and age < 50 and sex = "female" ] * 400 * 6 * 7 )
    set calories-required calories-required + ( count people with [ age >= 50 and sex = "female" ] * 2450 * 365 )
    set calories-required calories-required + ( count people with [ age < 1 ] * 675 * 365 )
    set calories-required calories-required + ( count people with [ age >= 1 and age < 5 ] * 1360 * 365 )
    set calories-required calories-required + ( count people with [ age >= 5 and age < 10 ] * 2010 * 365 )
    set calories-required calories-required + ( count people with [ age >= 10 and age < 16 and sex = "male" ] * 2750 * 365 )
    set calories-required calories-required + ( count people with [ age >= 10 and age < 16 and sex = "female" ] * 2420 * 365 )
    set min-grain-store ( ( calories-required * %-calories-from-crops ) / 3110 ) * store-size
    set fuel-requirement count people * 365 * daily-per-capita-fuel-use
    set fuel-store 0
  ]
end 

to update-settlements-2
  ask settlements [ ;; checks whether a settlement contains a least one adult or if a settlement is devoid of any inhabitants. If so, the settlement is removed and any remaining dependents sent to the nearest settlement. Any coppiced plot managed by the removed settlement reverts to unmanaged woodland and livestock owned by the removed settlement are removed also.
    set people ( turtle-set persons with [ my-house = myself ] )
    if count people = 0 [
      ask livestock [
        die
      ]
      if any? catchment with [ use = "coppice" and patch-owner = myself ] [
        ask catchment with [ use = "coppice" and patch-owner = myself ] [
          set use "forest"
        ]
      ]
      ask catchment with [ patch-owner = myself ] [
        set patch-owner nobody
      ]
      die
    ]
    if count people with [ age >= 16 and age < 50 ] = 0 [
      if any? catchment with [ use = "coppice" and patch-owner = myself ] [
        ask catchment with [ use = "coppice" and patch-owner = myself ] [
          set use "forest"
        ]
      ]
      ask catchment with [ patch-owner = myself ] [
        set patch-owner nobody
      ]
      ifelse any? other settlements with [ self != myself ] [
        let a one-of other settlements with [ self != myself ]
        ask people [
          set my-house a
        ]
        ask livestock [
          die
        ]
        die
      ]
      [
        ask people [
          die
        ]
        ask livestock [
          die
        ]
        die
      ]
    ]
    set people ( turtle-set persons with [ my-house = myself ] )
    set livestock ( turtle-set animals with [ my-owner = myself ] )
  ]
end 

to calculate-land-arable
  ask settlements [
    set arable-land 0
    set min-arable-land ( ( min-grain-store / basic-yield ) + ( ( ( min-grain-store / basic-yield ) * sowing-rate ) / basic-yield ) ) ;; first calculates the minimum area that each settlement must cultivate to produce sufficient food, sowing seed and a buffer.
    set min-arable-land-list lput min-arable-land min-arable-land-list
    set max-arable-land-land count catchment with [ use != "coppice" and countdown-fallow = 0 and landscape-type = "levee" ] ;; calculates the maximum area of land that can be cultivated as restricted by land availability
    if max-arable-land-land < 0 [
      set max-arable-land-land 0
    ]
    set max-arable-land-labour count people with [ age >= 16 and age < 50 ] * 3.2 ;; calculates the maximum area of land that can be cultivated with available land
    if max-arable-land-labour < 0 [
      set max-arable-land-labour 0
    ]
    set max-arable-land-grain ( grain-store / sowing-rate ) ;; calculates the maximum area of land that can be cultivated with available sowing seed.
    if max-arable-land-grain < 0 [
      set max-arable-land-grain 0
    ]
    let max-arable-land min ( list max-arable-land-land max-arable-land-labour max-arable-land-grain ) ;; sets the maximum area of land as the lower of the three areas calculated above.
    ifelse min-arable-land <= max-arable-land [
      set arable-land min-arable-land ;; sets the area of land to be cultivated as the minimum area of land or the maximum area of land, whichever is lower.
      if strategy-arable = "extensification" and surplus-grain > 0 [ ;; if settlements undertake extensification as per interface parameter, the extra area of land that can be cultivated with available land, labour or sowing seed is calculated.
        let d max-arable-land-land - arable-land
        let f max-arable-land-labour - arable-land
        let g ( surplus-grain / sowing-rate )
        let extra-land min ( list d f g )
        set surplus-grain surplus-grain - ( extra-land * sowing-rate )
        set arable-land arable-land + extra-land ;; increases the area of land to be cultivated by the area of extra land that can be cultivated when settlements practice extensification.
      ]
    ]
    [
      set arable-land max-arable-land
    ]
    if arable-land < 0 [
      set arable-land 0
    ]
    set surplus-grain 0
    set grain-store grain-store - ( arable-land * sowing-rate ) ;; reduces grain store by the quantity needed to sow the area of land to be cultivated
    if count catchment with [ landscape-type = "levee" and use != "forest" and use != "coppice" and countdown-fallow = 0 ] >= arable-land [ ;; updates the nearest patches of arable land to the settlement to reflect its use in the current year and resets the fallowing countdown.
      ask min-n-of arable-land catchment with [ landscape-type = "levee" and  use != "forest" and use != "coppice" and countdown-fallow = 0 ] [ distance myself ] [
        set use "arable"
        set pcolor brown + 2
        set countdown-fallow fallow-time
      ]
    ]
    if count catchment with [ landscape-type = "levee" and  use != "forest" and use != "coppice" and countdown-fallow = 0 ] < arable-land [ ;; if any potential arable land contains woodland but is requried for arable farming, the woodland is removed and the fuel store of the settlements in increased accordingly.
      let x count catchment with [ landscape-type = "levee" and  use != "forest" and use != "coppice" and countdown-fallow = 0 ]
      let y arable-land - x
      ask min-n-of x catchment with [ landscape-type = "levee" and  use != "forest" and use != "coppice" and countdown-fallow = 0 ] [ distance myself ] [
        set use "arable"
        set pcolor brown + 2
        set countdown-fallow fallow-time
      ]
    ask min-n-of y catchment with [ landscape-type = "levee" and   use != "coppice" ] [ distance myself ] [
      set use "arable"
      set pcolor brown + 2
      set biomass 0
      ask myself [
        set fuel-store fuel-store + [ biomass ] of myself
      ]
    ]
  ]
  if strategy-arable = "intensification" [ ;; calculates the labour expenditure for manuring (when settlements undertake intensification only), ploughing, sowing and harvesting.
    set manuring-labour-1 ( arable-land * manuring-time )
    set manuring-labour-2 ( arable-land * manuring-time ) / ( count people with [ age >= 16 and age < 50 ] )
    ]
  set ploughing-labour-1 ( arable-land *  ploughing-time )
  set ploughing-labour-2 ( arable-land * ploughing-time ) / ( count people with [ age >= 16 and age < 50 ] )
  set sowing-labour-1 ( arable-land * sowing-time )
  set sowing-labour-2 ( arable-land * sowing-time ) / ( count people with [ age >= 10 ] )
  set harvesting-labour-1 ( arable-land * harvesting-time )
  set harvesting-labour-2 ( arable-land * harvesting-time ) / ( count people with [ age >= 16 and age < 50 ] )
  ]
end 

to calculate-yield-arable
  let factor ( -0.2 + random-float 0.4 )
  ask settlements [
    set yield-grain ( arable-land * ( basic-yield * ( 1 + factor ) ) ) ;; calculates the yield of grain as the area of land cultivated multiplied by the basic yield and increased/decreased randomly within the range +/- 20%.
    if strategy-arable = "intensification" [
      ifelse cattle-manure-yield >= ( arable-land * 10000 ) [ ;; calculates the extra yield of grain as a result of incorporating manure into the soil. The amount of nitrogen added depends on the amount of manure which comes from cattle herds.
        let a ( arable-land * ( 10000 * N-content-manure * yield-increase-manure ) * ( 1 + factor ) )
        set yield-grain yield-grain + a
      ]
      [
        let b ( cattle-manure-yield / arable-land )
        let c ( arable-land * ( b * N-content-manure * yield-increase-manure ) * ( 1 + factor ) )
        set yield-grain yield-grain + c
      ]
    ]
    set grain-store yield-grain
  ]
end 

to calculate-surplus-arable
  ask settlements [
    if grain-store > min-grain-store [
      set surplus-grain ( grain-store - min-grain-store ) ;; reduces the grain yield by the amount required by the inhabitants for consumption, buffer and sowing seed
      set surplus-grain surplus-grain * ( 1 - surplus-takeoff )
    ]
    while [ any? other settlements with [ surplus-grain > 0 ] and grain-store < ( ( calories-required * %-calories-from-crops ) / calories-in-crops ) ] [ ;; if settlements produce too little grain, grain can be taken from another settlement or other settlements with surplus grain. The surplus grain of the other settlement(s) is reduced accordingly.
      let a one-of other settlements with [ surplus-grain > 0 ]
      ifelse [ surplus-grain ] of a >= ( ( calories-required * %-calories-from-crops ) / calories-in-crops ) - grain-store [
         ask a [
           set surplus-grain surplus-grain - ( [ min-grain-store - grain-store ] of myself )
         ]
         set grain-store min-grain-store
      ]
      [
        set grain-store grain-store + [ surplus-grain ] of a
        ask a [
          set surplus-grain 0
        ]
      ]
    ]
    if grain-store < ( ( calories-required * %-calories-from-crops ) / calories-in-crops ) [ ;; if settlements can not produce or borrow enough grain, a famine is recorded.
      set grain-deficit ( ( calories-required * %-calories-from-crops ) / calories-in-crops ) - grain-store
      set count-famines count-famines + 1
    ]
  ]
end 

to set-mortality-rates ;; sets the mortality rates of each animal depending on age range, species and exploitations strategy
  if sheep-strategy = "milk" [
    set SYMR 0.44 ;; mortality rate of young sheep
    set SIMR 0.01 ;; mortality rate of immature sheep
    set SAMR 0.01 ;; mortality rate of adult sheep
  ]
  if sheep-strategy = "meat" [
    set SYMR 0.01
    set SIMR 0.45
    set SAMR 0.01
  ]
  if sheep-strategy = "wool" [
    set SYMR 0.1
    set SIMR 0.2
    set SAMR 0.1
  ]
  if cattle-strategy = "milk" [
    set CYMR 0.5 ;; mortality rate of young cattle
    set CIMR 0.01 ;; mortality rate of immature cattle
    set CAMR 0.08 ;; mortality rate of adult cattle
  ]
  if cattle-strategy = "meat" [
    set CYMR 0.01
    set CIMR 0.45
    set CAMR 0.01
  ]
  if cattle-strategy = "manure" [
    set CYMR 0.2
    set CIMR 0
    set CAMR 0.2
  ]
  set HIMR 0.55 ;; removal rate of surplus immature horses
end 

to births-animals
  ask animals [
    set lactating "N"
  ]
  ask animals with [ species = "sheep" and age >= 2 ] [
    if random-float 1.0 < fertility [ ;; for each adult sheep a random number between 0 and 1 is generated. If this is less than the fertility rate of female sheep, the sheep will reproduce. The sex is assigned randomly.
      ifelse random-float 1.0 < twinning-rate-sheep [ ;; for each adult sheep that will reproduce, a random number is generated. If this number is less than the probability that than twinning rate of sheep, two offspring are produced. Otherwise one offspring is produced.
        hatch 2 [
          create-link-with myself
          set breed animals
          set species "sheep"
          set age 0
          set sex one-of ( list "male" "female" )
          set survivorship random-float 1.0
          set fertility 0.8
          set my-owner [ my-owner ] of myself
        ]
        set lactating "Y"
      ]
      [
        hatch 1 [
          create-link-with myself
          set breed animals
          set species "sheep"
          set age 0
          set sex one-of ( list "male" "female" )
          set survivorship random-float 1.0
          set fertility 0.8
          set my-owner [ my-owner ] of myself
        ]
        set lactating "Y"
      ]
    ]
  ]
  ask animals with [ species = "cattle" and age >= 3 ] [
    if random-float 1.0 < fertility [ ;; for each adult cattle a random number between 0 and 1 is generated. If this is less than the fertility rate of female cattle, the cow will reproduce. Sex is assigned randomly.
      hatch 1 [
        create-link-with myself
        set breed animals
        set species "cattle"
        set age 0
        set sex one-of ( list "male" "female" )
        set survivorship random-float 1.0
        set fertility 0.7
        set my-owner [ my-owner ] of myself
      ]
      set lactating "Y"
    ]
  ]
  ask animals with [ species = "horse" and age >= 3 and sex = "female" ] [ ;; for each adult horse a random number between 0 and 1 is generated. If this is less than the fertility rate of female horses, the horse will reproduce. Sex is assigned randomly.
    if random-float 1.0 < fertility [
      hatch 1 [
        set breed animals
        set species "horse"
        set age 0
        set sex one-of ( list "male" "female" )
        set survivorship random-float 1.0
        set fertility 0.6
        set my-owner [ my-owner ] of myself
      ]
    ]
  ]
  ask settlements [
    set livestock ( turtle-set animals with [ my-owner = myself ] )
  ]
end 

to natural-mortality
  ask animals with [ species = "sheep" and age < 1 ] [ ;; for each animal, if a random number between 0 and 1 is less than the mortality rate, the animal dies. These commands mimic deaths due to natural mortality.
    if random-float 1.0 < 0.32 [
      die
    ]
  ]
  ask animals with [ species = "cattle" and age < 1 ] [
    if random-float 1.0 < 0.2 [
      die
    ]
  ]
  ask animals with [ species = "horse" and age < 1 ] [
    if random-float 1.0 < 0.2 [
      die
    ]
  ]
  ask animals with [ species = "sheep" ] [
    let survivorship2 exp ( ( - annual-mortality-rate * floor age ) - exp ( - alphaS / alpha ) * ( exp ( floor age / alpha ) - 1 ) )
    if survivorship > survivorship2 [
      die
    ]
  ]
  ask animals with [ species = "cattle" ] [
    let survivorship2 exp ( ( - annual-mortality-rate * floor age ) - exp ( - alphaC / alpha ) * ( exp ( floor age / alpha ) - 1 ) )
    if survivorship > survivorship2 [
      die
    ]
  ]
  ask animals with [ species = "horse" ] [
    let survivorship2 exp ( ( - annual-mortality-rate * floor age ) - exp ( - alphaH / alpha ) * ( exp ( floor age / alpha ) - 1 ) )
    if survivorship > survivorship2 [
      die
    ]
  ]
end 

to slaughter
  ask settlements [
    set cattle-meat-yield 0
    set sheep-meat-yield 0
    set cattle-milk-yield 0
    set sheep-milk-yield 0
    set sheep-wool-yield 0
    set cattle-manure-yield 0
    set horse-surplus 0
    set pasture-land 0
    set meadow-land 0
    set fodder-labour-1 0
    set fodder-labour-2 0
    set SNM 0
    set CNM 0
    set SYM 0
    set CYM 0
    set SIM 0
    set CIM 0
    set SAM 0
    set CAM 0
    ask livestock with [ species = "sheep" and sex = "male" ] [ ;; for each animal, a random number is generate between 0 and 1. If the mortality rate is more than the ranodmly-generated number, the animal dies (or for horse is removed). In this sub-process the deaths of animals are recorded to calculated meat yields and surplus horses available each year.
      ask my-owner [ ;; animals are slaughtered in an order determined by their age. First male neonatal animals are slaughtered, followed by young animals, then immature animals and finally adult animals.
        set SNM SNM + 1
      ]
      die
    ]
    ask livestock with [ species = "cattle" and sex = "male" ] [
      ask my-owner [
        set CNM CNM + 1
      ]
      die
    ]
    ask livestock with [ species = "horse" and age >= 1 and age < 3 ] [
      if random-float 1.0 < HIMR [
        ask my-owner [
          set horse-surplus horse-surplus + 1
        ]
        die
      ]
    ]
    ask livestock with [ species = "sheep" and age < 1 ] [
      if random-float 1.0 < SYMR [
        ask my-owner [
          set SYM SYM + 1
        ]
        die
      ]
    ]
    ask livestock with [ species = "cattle" and age < 1 ] [
      if random-float 1.0 < CYMR [
        ask my-owner [
          set CYM CYM + 1
        ]
        die
      ]
    ]
    let a ( count livestock with [ species = "sheep" and age >= 2 ] / pasture-land-sheep ) ;; pasture land required per settlement for animal herds is calculated
    let b ( ( count livestock with [ species = "sheep" and age >= 1 and age < 2 ] * 0.8 ) / pasture-land-sheep )
    let c ( ( count livestock with [ species = "sheep" and age < 1 ] * 0.15 ) / pasture-land-sheep )
    let SLR a + b + c
    let d ( count livestock with [ species = "cattle" and age >= 3 ] / pasture-land-cattle )
    let f ( ( count livestock with [ species = "cattle" and age >= 1 and age < 3 ] * 0.8 ) / pasture-land-cattle )
    let g ( ( count livestock with [ species = "cattle" and age < 1 ] * 0.15 ) / pasture-land-cattle )
    let CLR d + f + g
    let h ( count livestock with [ species = "horse" and age >= 3 ] / pasture-land-horse )
    let i ( ( count livestock with [ species = "horse" and age >= 1 and age < 3 ] * 0.8 ) / pasture-land-horse )
    let j ( ( count livestock with [ species = "horse" and age < 1 ] * 0.15 ) / pasture-land-horse )
    let HLR h + i + j
    set pasture-land SLR + CLR + HLR
    set cattle-milk-yield ( count animals with [ species = "cattle" and lactating = "Y" and count link-neighbors = 0 ] * milk-yield-cattle * lactation-length-cattle ) ;; milk yields per animal herd per settlement are calculated
    set cattle-milk-yield cattle-milk-yield + ( ( count animals with [ species = "cattle" and lactating = "Y" and count link-neighbors > 0 ] / 2 ) * milk-yield-cattle * lactation-length-cattle )
    set sheep-milk-yield ( count animals with [ species = "sheep" and lactating = "Y" and count link-neighbors = 0 ] * milk-yield-sheep * lactation-length-sheep )
    set sheep-milk-yield sheep-milk-yield + ( ( count animals with [ species = "sheep" and lactating = "Y" and count link-neighbors = 0 ] / 2 ) * milk-yield-sheep * lactation-length-sheep )
    set sheep-wool-yield ( count livestock with [ species = "sheep" and age >= 1 ] * wool-yield-sheep )
    ask livestock with [ species = "sheep" and age >= 2 ] [
      if random-float 1.0 < SAMR [
        ask my-owner [
          set SAM SAM + 1
        ]
        die
      ]
    ]
    ask livestock with [ species = "sheep" and age >= 1 and age < 2 ] [
      if random-float 1.0 < SIMR [
        ask my-owner [
          set SIM SIM + 1
        ]
        die
      ]
    ]
    ask livestock with [ species = "cattle" and age >= 3 ] [
      if random-float 1.0 < CAMR [
        ask my-owner [
          set CAM CAM + 1
        ]
        die
      ]
    ]
    ask livestock with [ species = "cattle" and age >= 1 and age < 3 ] [
      if random-float 1.0 < CIMR [
        ask my-owner [
          set CIM CIM + 1
        ]
        die
      ]
    ]
    set cattle-meat-yield CAM * ( adult-weight-cattle * %-edible-carcass-cattle ) + CIM * ( immature-weight-cattle * %-edible-carcass-cattle ) + CYM * ( young-weight-cattle * %-edible-carcass-cattle ) ;; calculates total meat yields per settlement from animal herds
    set sheep-meat-yield SAM * ( adult-weight-sheep * %-edible-carcass-sheep ) + SIM * ( immature-weight-sheep * %-edible-carcass-sheep ) + SYM * ( young-weight-sheep * %-edible-carcass-sheep )
    set cattle-manure-yield ( ( count livestock with [ species = "cattle" and age >= 3 ] * manure-daily-yield * adult-weight-cattle ) + ( count livestock with [ species = "cattle" and age >= 1 and age < 3 ] * manure-daily-yield * immature-weight-cattle ) + ( count livestock with [ species = "cattle" and age < 1 ] * manure-daily-yield * young-weight-cattle ) ) * 120
    let SFR ( ( count livestock with [ species = "sheep" and age >= 2 ] ) + ( count livestock with [ species = "sheep" and age >= 1 and age < 2 ] * 0.8 ) + ( count livestock with [ species = "sheep" and age < 1 ] * 0.15 ) ) * fodder-sheep ;; calculates the quantity of fodder needed each winter for each animal herd.
    let CFR ( ( count livestock with [ species = "cattle" and age >= 3 ] ) + ( count livestock with [ species = "cattle" and age >= 1 and age < 3 ] * 0.8 ) + ( count livestock with [ species = "cattle" and age < 1 ] * 0.15 ) ) * fodder-cattle
    let HFR ( ( count livestock with [ species = "horse" and age >= 3 ] ) + ( count livestock with [ species = "horse" and age >= 1 and age < 3 ] * 0.8 ) + ( count livestock with [ species = "horse" and age < 1 ] * 0.15 ) ) * fodder-horse
    set meadow-land ( SFR + CFR + HFR ) / yield-grassland
    set fodder-labour-1 ( meadow-land * fodder-collection-time ) ;; labour expenditure per settlement for fodder collection is calculated.
    set fodder-labour-2 ( meadow-land * fodder-collection-time ) / ( count people with [ age >= 16 and age < 50 ] )
  ]
end 

to calc-workforce-fuel
  ask settlements [
    set fuel-workforce turtle-set [ ]
    set fuel-labour-1 0
    set fuel-labour-2 0
    let a fuel-requirement / ( 365 / collection-frequency )
    let b count people with [ age >= 16 and age < 50 and sex = "male" ] * max-load-adult-male ;; calculates the minimum number of inhabitants required to collect sufficient fuel. ROMFARMS seeks to send the fewest number of "strong" workforce (adult males and females) before it utilises the labour of the "weak" workforce (adolescents and the elderley).
    if b > a [
      set fuel-workforce turtle-set n-of ( ceiling ( a / max-load-adult-male ) ) people with [ age >= 16 and age < 50 and sex = "male" ]
    ]
    if b = a [
      set fuel-workforce turtle-set people with [ age >= 16 and age < 50 and sex = "male" ]
    ]
    if b < a [
      set fuel-workforce turtle-set people with [ age >= 16 and age < 50 and sex = "male" ]
      let c ( a - b )
      let d count people with [ age >= 16 and age < 50 and sex = "female" ] * max-load-adult-female
      if d > c [
        set fuel-workforce ( turtle-set fuel-workforce n-of ( ceiling ( c / max-load-adult-female ) ) people with [ age >= 16 and age < 50 and sex = "female" ] )
      ]
      if d = c [
        set fuel-workforce ( turtle-set fuel-workforce people with [ age >= 16 and age < 50 and sex = "female" ] )
      ]
      if d < c [
        set fuel-workforce ( turtle-set fuel-workforce people with [ age >= 16 and age < 50 and sex = "female" ] )
        let f ( a - ( b + d ) )
        let g count people with [ age >= 10 and age < 16 or age > 50 ] * max-load-other
        if g > f [
          set fuel-workforce ( turtle-set fuel-workforce n-of ( ceiling ( f / max-load-other ) ) people with [ age >= 10 and age < 16 or age > 50 ] )
        ]
        if g = f [
          set fuel-workforce ( turtle-set fuel-workforce people with [ age >= 10 and age < 16 or age > 50 ] )
        ]
        if g < f [
          set fuel-workforce ( turtle-set fuel-workforce people with [ age >= 10 and age < 16 or age > 50 ] )
        ]
      ]
    ]
    set fuel-workforce-list lput count fuel-workforce fuel-workforce-list
    repeat ceiling ( 365 / collection-frequency ) [
      find-fuel
    ]
  ]
end 

to calc-workforce-construction
  ask patches with [ use = "forest" or use = "coppice" ] [
    set biomass-forest-list lput biomass biomass-forest-list
  ]
  ask patches with [ use = "forest" or use = "coppice" or use = "alt-wood"  ] [
    set biomass-list lput biomass biomass-list
  ]
  ask settlements [ ;; calculates the minimum number of inhabitants required to collect timber. Only members of the "strong" workforce can collect timber.
    set construction-labour 0
    if age = reconstruction-frequency [
      set construction-workforce turtle-set [ ]
      let a count people with [ age >= 16 and age < 50 and sex = "male" ] * max-load-adult-male
      let b count people with [ age >= 16 and age < 50 and sex = "female" ] * max-load-adult-female
      if a >= construction-requirement [
        set construction-workforce ( turtle-set n-of ceiling ( construction-requirement / max-load-adult-male ) people with [ age >= 16 and age < 50 and sex = "male" ] )
      ]
      if a < construction-requirement [
        set construction-workforce ( turtle-set people with [ age >= 16 and age < 50 and sex = "male" ] )
        let c construction-requirement - a
        if b >= c [
          set construction-workforce ( turtle-set construction-workforce n-of ceiling ( c / max-load-adult-female ) people with [ age >= 16 and age < 50 and sex = "female" ] )
        ]
        if b < c [
          set construction-workforce ( turtle-set construction-workforce people with [ age >= 16 and age < 50 and sex = "female" ] )
        ]
      ]
      while [ any? patches with [ use != "alt-wood" and biomass > 0 ] and construction-store < construction-requirement ] [
        find-timber
      ]
      set construction-workforce-list lput count construction-workforce construction-workforce-list
      set construction-workforce turtle-set [ ]
    ]
  ]
end 

to setup-forest
  ask n-of ( count patches with [ landscape-type = "levee" or landscape-type = "floodbasin" ] * forest-cover ) patches with [ landscape-type = "levee" or landscape-type = "floodbasin" ] [
    set use "forest"
    if landscape-type = "levee" [
      set biomass ( 100 + random 20 ) * 439 ;; 100 +/- 20m3 is volume wood per ha, 439kg/m3 is density of wood
    ]
    if landscape-type = "floodbasin" [
      set biomass ( 110 + random 30 ) * 439 ;; see above
    ]
  ]
    ask n-of ( fen-cover * count patches with [ pcolor = black ] ) patches with [ pcolor = black ] [
      set use "alt-wood"
      set landscape-type "fen"
      set biomass ( 65 + random 20 ) * 439 ;; see above
    ]
    ask patches with [ biomass > 0 ] [
      set pcolor scale-color green biomass 100000 1000
    ]
end 

to config-settlements
  set calories-required ( count people with [ age >= 16 and age < 50 and sex = "male" ] * 3250 * 365 + count people with [ age >= 16 and age < 50 and sex = "male" ] * 550 * 6 * 7 ) ;; sets calories-required as annual requirement for adult men (3250 per day ) plus extra calories for 6 weeks heavy labour
  set calories-required calories-required + ( count people with [ age >= 16 and age < 50 and sex = "female" ] * 2800 * 365 + count people with [ age >= 6 and age < 50 and sex = "female" ] * 400 * 6 * 7 ) ;; adds annual requirement for adult women to calorie requirement (2800 per day) plus extra for six weeks hard labour
  set calories-required calories-required + ( count people with [ age >= 50 and sex = "male" ] * 2650 * 365 ) ;; adds requirement of elderly males (aged >= 50 )to calorie requirement
  set calories-required calories-required + ( count people with [ age >= 50 and sex = "female" ] * 2450 * 365 ) ;; adds requirement of elderly females (aged >= 50) to calorie requirement
  set calories-required calories-required + ( count people with [ age < 1 ] * 675 * 180 + count people with [ age < 1 ] * 285 * 90 + count people with [ age < 1 ] * 475 * 90 ) ;; adds requirement of lactating adult females to calorie requirement
  set calories-required calories-required + ( count people with [ age >= 1 and age < 5 ] * 1360 * 365 ) ;; adds requirement of 2nd cohort persons (aged 1-4) to calorie requirement
  set calories-required calories-required + ( count people with [ age >= 5 and age < 10 ] * 2010 * 365 ) ;; adds requirement of 3rd cohort persons (aged 5-9) to calorie requirement
  set calories-required calories-required + ( count people with [ age >= 10 and age < 16 and sex = "male" ] * 2750 * 365 ) ;; adds requirement of male 4th cohort (aged 10-15) to calorie requirement
  set calories-required calories-required + ( count people with [ age >= 10 and age < 16 and sex = "female" ] * 2420 * 365 ) ;; adds requirement of female 4th cohort (aged 10-15) to calorie requirement
  set min-grain-store ( ( calories-required * %-calories-from-crops ) / calories-in-crops ) * store-size ;; sets minimum amount of grain required by settlement as amount of grain to satisfy a % of the total calories required (determined by %-calories-from-crops input) plus a buffer (determined by store-size input)
  set grain-store ( min-grain-store + ( ( min-grain-store / basic-yield ) * 200 ) ) ;; sets initial grain-store as the minimum grain store
  set fuel-target nobody
  set fuel-requirement count people * 365 * daily-per-capita-fuel-use
  set fuel-labour-1 0
  set fuel-labour-2 0
  set fuel-store 0
  set construction-labour 0
  set construction-requirement 8525.4 * no-households
  set construction-store 0
  set construction-target nobody
  if cattle? = TRUE [ ;; generates herds of cattle, sheep and horses for each settlement.
    repeat 30 [
      hatch 1 [
        ht
        set breed animals
        set species "cattle"
        set age 3
        set sex "female"
        set fertility 0.7
        set survivorship random-float 1.0
        set my-owner myself
        ask myself [
          set livestock ( turtle-set livestock myself )
        ]
      ]
    ]
  ]
  if sheep? = TRUE [
    repeat 30 [
      hatch 1 [
        ht
        set breed animals
        set species "sheep"
        set age 2
        set sex "female"
        set fertility 0.8
        set survivorship random-float 1.0
        set my-owner myself
        ask myself [
          set livestock ( turtle-set livestock myself )
        ]
      ]
    ]
  ]
  if horse? = TRUE [
    repeat 30 [
      hatch 1 [
        ht
        set breed animals
        set species "horse"
        set age 3
        set sex one-of ( list "male" "female" )
        set fertility 0.6
        set survivorship random-float 1.0
        set my-owner myself
        ask myself [
          set livestock ( turtle-set livestock myself )
        ]
      ]
    ]
  ]
  set catchment patch-set [ ]
  set catchment ( patch-set catchment patches with [ landscape-type = "levee" and not any? settlements-here ] in-radius ( catchment-area * 50 ) )
  set catchment ( patch-set catchment patch-here )
  if coppicing? = TRUE and count catchment > 1 [
      ask one-of catchment with [ use != "forest" and use != "coppice" ] [
      set use "coppice"
      set patch-owner myself
      set biomass ( 180 + random 40 ) * 439
      set pcolor scale-color green biomass 100000 1000
    ]
  ]
  ask patch-here [
    set patch-owner myself
  ]
end 

to set-fertility
  ask persons with [ my-spouse != nobody and sex = "female" ] [
    if age >= 16 and age < 19 [
      set fertility 0.411
    ]
    if age >= 19 and age < 24 [
      set fertility 0.46
    ]
    if age >= 24 and age < 29 [
      set fertility 0.431
    ]
    if age >= 29 and age < 34 [
      set fertility 0.395
    ]
    if age >= 34 and age < 39 [
      set fertility 0.322
    ]
    if age >= 39 and age < 44 [
      set fertility 0.167
    ]
    if age >= 44 and age < 50 [
      set fertility 0.024
    ]
  ]
end 

to set-mortality
  ask persons [
    if age >= 0 and age < 1 [
      set mortality 0.3056
    ]
    if age >= 1 and age < 5 [
      set mortality 0.2158 / 4
    ]
    if age >= 5 and age < 10 [
      set mortality 0.0606 / 5
    ]
    if age >= 10 and age < 15 [
      set mortality 0.0474 / 5
    ]
    if age >= 15 and age < 20 [
      set mortality 0.0615 / 5
    ]
    if age >= 20 and age < 25 [
      set mortality 0.0766 / 5
    ]
    if age >= 25 and age < 30 [
      set mortality 0.0857 / 5
    ]
    if age >= 30 and age < 35 [
      set mortality 0.0965 / 5
    ]
    if age >= 35 and age < 40 [
      set mortality 0.1054 / 5
    ]
    if age >= 40 and age < 45 [
      set mortality 0.1123 / 5
    ]
    if age >= 45 and age < 50 [
      set mortality 0.1197 / 5
    ]
    if age >= 50 and age < 55 [
      set mortality 0.1529 / 5
    ]
    if age >= 55 and age < 60 [
      set mortality 0.1912 / 5
    ]
    if age >= 60 and age < 65 [
      set mortality 0.2715 / 5
    ]
    if age >= 65 and age < 70 [
      set mortality 0.3484 / 5
    ]
    if age >= 70 and age < 75 [
      set mortality 0.4713 / 5
    ]
    if age >= 75 and age < 80 [
      set mortality 0.6081 / 5
    ]
    if age >= 80 and age < 85 [
      set mortality 0.7349 / 5
    ]
    if age >= 85 and age < 90 [
      set mortality 0.8650 / 5
    ]
    if age >= 90 and age < 95 [
      set mortality 0.9513 / 5
    ]
    if age >= 95 [
      set mortality 1
    ]
  ]
end 

to find-fuel ;; sub-process is looped until workforces have collected the maximum amount of fuel in the landscape or enough fuel.
  while [ any? fuel-workforce with [ load < max-load ] and any? patches with [ biomass > 0 ] ] [ ;; settlements target a specific patch containing woodland.
    ifelse any? catchment with [ use = "coppice" and patch-owner = myself and biomass > 0 ] [
      set fuel-target one-of catchment with [ use = "coppice" and biomass > 0 ]
    ]
    [
      ifelse any? patches with [ use = "forest" and biomass > mean ( biomass-forest-list ) ] [
        set fuel-target max-one-of patches with [ use = "forest" and biomass > 0 ] [ distance myself ]
      ]
      [
        ifelse any? patches with [ use = "forest" and biomass > 0 ] [
          set fuel-target min-one-of patches with [ use = "forest" and biomass > 0 ] [ distance myself ]
        ]
        [
        if any? patches with [ biomass > 0 ] [
          set fuel-target min-one-of patches with [ biomass > 0 ] [ distance myself ]
        ]
      ]
    ]
  ]
  if fuel-target != nobody [
    take-fuel
    set fuel-target nobody
  ]
  ]
  set fuel-store fuel-store + sum ( [ load ] of fuel-workforce ) ;; workforces process and collect fuel
  set fuel-labour-1 fuel-labour-1 + sum ( [ processing-time-fuel ] of fuel-workforce ) ;; time spent processing fuel per member of the workforce and the sum total for the whole workforce is calculated.
  set fuel-labour-2 fuel-labour-2 + ( sum ( [ processing-time-fuel ] of fuel-workforce ) / count fuel-workforce )
  ask fuel-workforce [
    let a patch-here
    move-to my-house
    set distance-travelled-fuel distance-travelled-fuel + distance a
    ask my-house [
      set fuel-labour-1 fuel-labour-1 + ( sum ( [ distance-travelled-fuel ] of fuel-workforce ) / 10 / walking-speed ) ;; the cumulative distance travelled per member of the workforce between patches and the settlement and the sum total for the whole workforce is calculated.
      set fuel-labour-2 fuel-labour-2 + ( ( sum ( [ distance-travelled-fuel ] of fuel-workforce ) / 10 / walking-speed ) / count fuel-workforce )
    ]
    set load 0
    set distance-travelled-fuel 0
    set processing-time-fuel 0
  ]
end 

to find-timber ;; same process as above
  while [ any? construction-workforce with [ load != max-load ] and any? patches with [ biomass > 0 ] ] [
    ifelse any? catchment with [ use = "coppice" and patch-owner  = myself and biomass > 0 ] [
      set construction-target max-one-of catchment with [ use = "coppice" and patch-owner = myself and biomass > 0 ] [ biomass ]
    ]
    [
      ifelse any? patches with [ use = "forest" and biomass > mean ( biomass-forest-list ) ] [
        set construction-target max-one-of patches with [ use = "forest" and biomass > mean ( biomass-forest-list ) ] [ biomass ]
      ]
      [
        if any? patches with [ use = "forest" and biomass > 0 ] [
          set construction-target min-one-of patches with [ use = "forest" and biomass > 0 ] [ distance myself ]
        ]
      ]
    ]
    if construction-target != nobody [
      take-timber
      set construction-target nobody
    ]
  ]
  set construction-store construction-store + sum ( [ load ] of construction-workforce )
  set construction-labour construction-labour + sum ( [ processing-time-timber ] of construction-workforce )
  ask construction-workforce [
    let a patch-here
    move-to my-house
    set distance-travelled-construction distance-travelled-construction + distance a
    ask my-house [
      set construction-labour construction-labour + ( ( sum ( [ distance-travelled-construction ] ) of construction-workforce ) / 10 / walking-speed )
    ]
    set load 0
    set distance-travelled-construction 0
    set processing-time-timber 0
  ]
end 

to new-settlement ;; creates a new settlement when a new married couple must leave their original settlement due to overcrowding. If settlement density will be exceeded, no new settlement is produced and the couple is removed.
  ifelse any? patches with [ landscape-type = "levee" and use != "settlement" and count settlements-on neighbors = 0 ] and ( precision ( ( count settlements + 1 ) / count patches with [ landscape-type = "levee" ] ) 4 ) <= settlement-density [
    let a self
    ask one-of patches with [ landscape-type = "levee" and use != "settlement" and count settlements-on neighbors = 0 ] [
      sprout 1 [
        set breed settlements
        set age 0
        set no-households [ no-households ] of [ my-house ] of a
        set color white
        set size 1 + ( ( no-households - 1 ) / 4 )
        set livestock turtle-set [ ]
        set people turtle-set [ ]
        set people ( turtle-set people a )
        set people ( turtle-set people [ my-spouse ] of a )
        ask a [
          set my-house myself
          ask my-spouse [
            set my-house [ my-house ] of a
          ]
        ]
        if [ biomass ] of patch-here > 0 [
          set fuel-store fuel-store + [ biomass ] of patch-here
          ask patch-here [
            set biomass 0
          ]
        ]
        config-settlements
      ]
    ]
  ]
  [
    ask my-spouse [
      die
    ]
    die
  ]
end 

to take-fuel
  ask fuel-workforce [
    let a patch-here
    move-to [ fuel-target ] of my-house
    set distance-travelled-fuel distance-travelled-fuel + distance a
    ifelse [ biomass ] of [ fuel-target ] of my-house >= ( max-load - load ) [
      ask [ fuel-target ] of my-house [
        set biomass biomass - [ max-load - load ] of myself
        if biomass = 0 [
          if use = "coppice" [
            set countdown-reforest 12
          ]
          if use = "forest" or use = "alt-wood" [
            set countdown-reforest 15
          ]
        ]
      ]
      set load load + ( max-load - load )
      set processing-time-fuel processing-time-fuel + fuel-collection-time
    ]
    [
      set load load + [ biomass ] of [ fuel-target ] of my-house
      set processing-time-fuel processing-time-fuel + fuel-collection-time
      ask [ fuel-target ] of my-house [
        set biomass 0
        if use = "coppice" [
          set countdown-reforest 12
        ]
        if use = "forest" [
          set countdown-reforest 15
        ]
      ]
    ]
  ]
end 

to take-timber
  ask construction-workforce [
    let a patch-here
    move-to [ construction-target ] of my-house
    set distance-travelled-construction distance-travelled-construction + distance a
    ifelse [ biomass ] of [ construction-target ] of my-house >= ( max-load - load ) [
      ask [ construction-target ] of my-house [
        set biomass biomass - [ max-load - load ] of myself
        if biomass = 0 [
          if use = "coppice" [
            set countdown-reforest 12
          ]
          if use = "forest" or use = "alt-wood" [
            set countdown-reforest 15
          ]
        ]
      ]
      set load load + ( max-load - load )
      set processing-time-timber processing-time-timber + timber-collection-time
    ]
    [
      set load load + [ biomass ] of [ construction-target ] of my-house
      set processing-time-timber processing-time-timber + timber-collection-time
      ask [ construction-target ] of my-house [
        set biomass 0
        if use = "coppice" [
          set countdown-reforest 12
        ]
        if use = "forest" [
          set countdown-reforest 15
        ]
      ]
    ]
  ]
end