AgroForestry: treecover on cropland and betr

CHANGELOG.md

@@ -7,10 +7,17 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 
 ### changed
--
+- **29_ageclass** module 29_ageclass has been renamed to 28_ageclass to make space for `29_cropland` just before `30_croparea`
+- **30_crop** module `30_crop` renamed to `30_croparea`, which now only accounts for crop area.
+- **30_crop** SNV implementation has been moved from `30_crop` to `29_cropland` 
+- **30_crop** the two realizations `penalty_apr22` and `rotation_apr22` have been merged into a single `30_croparea/detail_apr24` realization
+- **30_crop** the previous `30_crop/endo_apr21` realization has been moved to `30_croparea/simple_apr24`
+- **default.cfg** cfg$gms$s80_maxiter reduced from 30 to 10
 
 ### added
--
+- **29_cropland** new module `29_cropland` accounting for crop area, fallow cropland and tree cover on cropland with two realizations: `detail_apr24` and `simple_apr24` (default).
+- **10_land** added interface `pm_land_hist` with historic land use patterns
+- **32_forestry** added technical balance term `v32_land_missing_ndc`
 
 ### removed
 - **scripts/output/extra** removed scripts disaggregation_cropsplit and disaggregation_transitions

config/default.cfg

@@ -26,7 +26,7 @@ cfg$input <- c(regional    = "rev4.104_h12_magpie.tgz",
                cellular    = "rev4.104_h12_fd712c0b_cellularmagpie_c200_MRI-ESM2-0-ssp370_lpjml-8e6c5eb1.tgz",
                validation  = "rev4.104_h12_validation.tgz",
                additional  = "additional_data_rev4.48.tgz",
-               calibration = "calibration_H12_26Mar24.tgz")
+               calibration = "calibration_H12_default_30Apr24.tgz")
 
 # NOTE: It is recommended to recalibrate the model when changing cellular input data
 #       as well as for any other setting that would affect initial values in the model,
@@ -205,7 +205,7 @@ cfg$gms$land <- "landmatrix_dec18"          # def = landmatrix_dec18
 # * The balance variables in the land module avoid infeasibilities due to
 # * differences in accuracy between parameters and variables in GAMS.
 # * High costs make sure that the balance variables are only used as a last resort.
-cfg$gms$s10_cost_balance  <- 1000000   # def = 1000000
+cfg$gms$s10_cost_balance  <- 1e+06   # def = 1e+06
 
 
 # ***---------------------    11_costs   ------ --------------------------------
@@ -664,37 +664,20 @@ cfg$gms$s22_conservation_start <- 2020       # def = 2020
 # * Target year (year when full protection is reached):
 cfg$gms$s22_conservation_target <- 2030       # def = 2030
 
-# ***---------------------    29_ageclass    -----------------------------------
+# ***---------------------    28_ageclass    -----------------------------------
 # * (feb21): Distribution of age-classes according to Poulter et al 2018
 cfg$gms$ageclass    <- "feb21"               # def = feb21
 
-# ***---------------------    30_crop    ---------------------------------------
-# * (endo_apr21): Hard rotational constraints. Dynamic cropland and detailed cropland availability data at grid cell level.
-# * (rotation_apr22): hard rotational constraints and fallow constraints with the option of different future scenarios. Dynamic cropland and detailed cropland availability data at grid cell level.
-# * (penalty_apr22): rotational and fallow constraints are incentivized via penalty payments. Dynamic cropland and detailed cropland availability data at grid cell level.
+# ***---------------------    29_cropland    -----------------------------------
+# * Cropland is defined as the sum of croparea, fallow land and tree cover
+# * Croparea is provided by 30_crop.
+# * Fallow land and tree cover are defined by 29_cropland, 
+# * (simple_apr24): Fallow land and tree cover on cropland are fixed to zero
+# * (detail_apr24): Fallow land and tree cover based on rules or incentives
 # NOTE: It is recommended to recalibrate the model when changing this setting!
-cfg$gms$crop    <- "endo_apr21"               # def = endo_apr21
-# * (c30_bioen_type): switch for type of bioenergy crops; options: begr, betr, all
-cfg$gms$c30_bioen_type <- "all"               # def = "all"
-# * (c30_bioen_water): switch for irrigation of bioenergy crops; options: rainfed, irrigated, all
-cfg$gms$c30_bioen_water <- "rainfed"          # def = "rainfed"
-# * (c30_rotation_constraints): switch for rotational constraints: on, off
-cfg$gms$c30_rotation_constraints <- "on"       # def = "on"
-# * (c30_rotation_scenario): scenarios for constraints.
-# * In realization rotation_apr22: min (minimal constraints), default (best guess), good (good practice),
-# * good_20div (good practice - 20% for other crops), setaside (default plus fallow),
-# * legumes (minimum share of legumes), agroforestry (minimum share of perennials), sixfoldrotation
-# * (crops can only repeat after 6 years), agroecology (mix of previous scenarios)
-# * In realization penalty_apr22: none (no incentives), default (best guess), fallow (increased fallow incentives),
-# * legumes (increased incentives for legumes), agroforestry (increased incentives for perennials), agroecology (mix)
-# * In realization endo_apr21: no scenarios exist.
-cfg$gms$c30_rotation_scenario <- "default"     # def = "default"
-# * Year by which rotation scenario is fully implemented:
-# * Start year:
-cfg$gms$s30_rotation_scenario_start <- 2020       # def = 2020
-# * Target year (year when full implementation is reached):
-cfg$gms$s30_rotation_scenario_target <- 2050       # def = 2050
+cfg$gms$cropland    <- "simple_apr24"               # def = simple_apr24
 
+# *** Options for all cropland realizations ***
 
 # * Switch to determine whether marginal land (suitability index below 0.33) should be included
 # * in the total available cropland. Options are:
@@ -703,35 +686,121 @@ cfg$gms$s30_rotation_scenario_target <- 2050       # def = 2050
 # * ("no_marginal"): Marginal land is completely excluded from crop cultivation
 # * Note: Option "q33_marginal" produces the highest spatial correlation
 # * with observed cropland patterns and is recommended for productive runs.
-cfg$gms$c30_marginal_land <- "q33_marginal"   # def = "q33_marginal"
+cfg$gms$c29_marginal_land <- "q33_marginal"   # def = "q33_marginal"
 
 # * Share of available cropland that is withheld for maintaining semi-natural vegetation (SNV)
 # * in each square km in cropland areas, including grassland, forest and other land. For example,
 # * a share of 0.2 corresponds to 20 % of SNV in terms of the available cropland.
 # * The amount of cropland relocation is estimated based on external high resolution
 # * land cover information from the Copernicus Global Land Service for the year 2019.
 # * Accepted sensible values are between 0 and 0.5
-# Note: s30_snv_shr applies to countries selected in policy_countries30
-# s30_snv_shr_noselect applies to all other countries.
-cfg$gms$s30_snv_shr <- 0                # def = 0
-cfg$gms$s30_snv_shr_noselect <- 0       # def = 0
-# * Year by which SNV policy ('s30_snv_shr') is fully implemented.
+# Note: s29_snv_shr applies to countries selected in policy_countries29
+# s29_snv_shr_noselect applies to all other countries.
+cfg$gms$s29_snv_shr <- 0                # def = 0
+cfg$gms$s29_snv_shr_noselect <- 0       # def = 0
+# * Year by which SNV policy ('s29_snv_shr') is fully implemented.
 # * Start year (should be close to 2019):
-cfg$gms$s30_snv_scenario_start <- 2020       # def = 2020
+cfg$gms$s29_snv_scenario_start <- 2020       # def = 2020
 # * Target year (year when full implementation is reached):
-cfg$gms$s30_snv_scenario_target <- 2030       # def = 2030
+cfg$gms$s29_snv_scenario_target <- 2029       # def = 2029
 # * Switch and specification of countries for which SNV policy in
-# * s30_snv_shr apply.
+# * s29_snv_shr apply.
 # * Options: list of iso-codes of countries where SNV policy should be applied
 # * Note: must be written in the format: "IND, BRA, DEU"
 # * Default: all iso countries
-cfg$gms$policy_countries30  <- all_iso_countries
+cfg$gms$policy_countries29  <- all_iso_countries
 # * Land types included in the SNV policy. This option allows for sensitivity analyses.
 # * plausible options:  "secdforest, forestry, past, other",
 # *                     "secdforest, other",
 # *                     "secdforest, past, other" etc.
 cfg$gms$land_snv <- "secdforest, forestry, past, other"    #def = "secdforest, forestry, past, other"
 
+# *** Options only available for `detail_apr24` realization ***
+
+# * Minimum cluster share of treecover on total cropland area (including croparea, fallow land and tree cover).
+# * s29_treecover_target is faded in linearly between s29_treecover_scenario_start and s29_treecover_scenario_target.
+cfg$gms$s29_treecover_target <- 0   # def = 0
+# * Avoid loss of existing treecover (1=yes 0=no)
+cfg$gms$s29_treecover_keep <- 1   # def = 1
+# * Maximum share of treecover on total cropland (1)
+cfg$gms$s29_treecover_max <- 0.4   # def = 0.4
+# * Start year of tree cover share fade-in:
+cfg$gms$s29_treecover_scenario_start <- 2020   # def = 2020
+# * Target year (year when full implementation is reached):
+cfg$gms$s29_treecover_scenario_target <- 2050   # def = 2050
+# * Tree cover establishment cost (USD05MER per ha)
+cfg$gms$s29_cost_treecover_est <- 2000   # def = 2000
+# * Tree cover recurring cost (USD05MER per ha)
+cfg$gms$s29_cost_treecover_recur <- 500   # def = 500
+# * Penalty for violation of treecover target (USD05MER per ha)
+cfg$gms$s29_treecover_penalty <- 2000   # def = 2000
+
+# * Minimum cluster share of fallow land on total cropland area (including croparea, fallow land and tree cover).
+# * s29_fallow_target is faded in linearly between s29_fallow_scenario_start and s29_fallow_scenario_target.
+cfg$gms$s29_fallow_target <- 0   # def = 0
+# * Maximum share of fallow land on total cropland (1)
+cfg$gms$s29_fallow_max <- 0.4   # def = 0.4
+# * Start year of tree cover share fade-in:
+cfg$gms$s29_fallow_scenario_start <- 2020   # def = 2020
+# * Target year (year when full implementation is reached):
+cfg$gms$s29_fallow_scenario_target <- 2050   # def = 2050
+# * Penalty for violation of fallow target (USD05MER per ha)
+cfg$gms$s29_fallow_penalty <- 500   # def = 500
+
+# ***---------------------    30_croparea    ---------------------------------------
+# * 30_croparea defines the croparea, which is a subcomponent of total cropland defined in 29_cropland.
+# * (simple_apr24): Dynamic croparea with simple rotational constraints
+# * (detail_apr24): Dynamic croparea with detailed rules and incentives for rotational constraints
+# NOTE: It is recommended to recalibrate the model when changing this setting!
+cfg$gms$croparea    <- "simple_apr24"               # def = simple_apr24
+
+# *** Options for all croparea realizations ***
+
+# * (c30_bioen_type): switch for type of bioenergy crops; options: begr, betr, all
+cfg$gms$c30_bioen_type <- "all"               # def = "all"
+# * (c30_bioen_water): switch for irrigation of bioenergy crops; options: rainfed, irrigated, all
+cfg$gms$c30_bioen_water <- "rainfed"          # def = "rainfed"
+
+# * Minimum cluster share of bioenergy trees (betr) on total cropland area
+# * s30_betr_target is faded in linearly between s30_betr_scenario_start and s30_betr_scenario_target.
+cfg$gms$s30_betr_target <- 0   # def = 0
+# * Start year of tree cover share fade-in:
+cfg$gms$s30_betr_scenario_start <- 2020   # def = 2020
+# * Target year (year when full implementation is reached):
+cfg$gms$s30_betr_scenario_target <- 2050   # def = 2050
+# * Penalty for violation of fallow target (USD05MER per ha)
+cfg$gms$s30_betr_penalty <- 500   # def = 500
+
+# *** Options only available for `simple_apr24` realization ***
+
+# * (c30_rotation_constraints): switch for rotational constraints: on, off
+cfg$gms$c30_rotation_constraints <- "on"       # def = "on"
+
+# *** Options only available for `detail_apr24` realization ***
+
+# * Switch for rule-based (1) or penalty-based (0) implementation of rotation scenarios
+cfg$gms$s30_implementation <- 1   # def = 1
+
+# * Rotation rules:
+# * min (minimal constraints), default (best guess), good (good practice),
+# * good_20div (good practice - 20% for other crops), setaside (default plus fallow),
+# * legumes (minimum share of legumes), sixfoldrotation (crops can only repeat after 6 years), 
+# * agroecology (mix of previous scenarios), FSEC (similar to agroecology)
+# * betr0 (minimum share of short rotation agroforestry trees), betr10, betr20, betr25, betr30, betr40, betr50.
+cfg$gms$c30_rotation_rules <- "default"     # def = "default"
+
+# * Rotation incentives:
+# * none (no incentives), default (best guess), 
+# * legumes (increased incentives for legumes), agroecology (mix), 
+# * betr500 and betr1000 (incentives for short rotation agroforestry trees)
+cfg$gms$c30_rotation_incentives <- "none"     # def = "none"
+
+# * Year by which rotation scenario is fully implemented:
+# * Start year:
+cfg$gms$s30_rotation_scenario_start <- 2020       # def = 2020
+# * Target year (year when full implementation is reached):
+cfg$gms$s30_rotation_scenario_target <- 2050       # def = 2050
+
 # ***---------------------    31_past    ---------------------------------------
 # * (static):     static pasture
 # * (endo_jun13): dynamic pasture
@@ -1884,7 +1953,7 @@ cfg$gms$s73_expansion <- 0                     # def = 0
 cfg$gms$optimization <- "nlp_apr17"              # def = nlp_apr17
 
 # maximal number of solve iterations
-cfg$gms$s80_maxiter <- 30
+cfg$gms$s80_maxiter <- 10  # def = 10
 
 # Solver settings only for realization `lp_nlp_apr17`. All other realizations use `conopt4`.
 # * (conopt4):         conopt4
@@ -1896,7 +1965,6 @@ cfg$gms$c80_nlp_solver <- "conopt4"              # def = conopt4
 # * 0: default settings (optfile will be ignored)
 cfg$gms$s80_optfile <- 0 # def = 0
 
-
 #*******************************END MODULE SETUP********************************
 
 #### Other settings (e.g. clustering, gdx files, ...): ####

config/scenario_config.csv

@@ -31,9 +31,9 @@ gms$c21_trade_liberalization;;;;l908080r807070;l909090r808080;l909090r808080;l90
 gms$c22_protect_scenario;;;;none;none;none;none;none;none;BH;none;BH_IFL;BH;;;;;;;BH;;;;;BH_IFL;BH_IFL;BH_IFL;BH_IFL;BH_IFL;;;;;;;;;;;;;;;;;;;
 gms$c22_protect_scenario_noselect;;;;;;;;;;;;;;;;;;;;;;;;;none;none;BH_IFL;none;BH_IFL;;;;;;;;;;;;;;;;;;;
 gms$c30_bioen_water;;;;rainfed;rainfed;rainfed;rainfed;rainfed;rainfed;rainfed;all;rainfed;rainfed;;;;;;;rainfed;;;rainfed;all;;;;;;;;;;;;;;;;;;;;;;;;
-gms$s30_snv_shr;;;;0;0;0;0;0;0;0;0;0;0.2;;;;;;;0;;;;;0.2;0.2;0.2;0.2;0.2;;;;;;;;;;;;;;;;;;;
-gms$s30_snv_shr_noselect;;;;;;;;;;;;;;;;;;;;;;;;;0;0;0.2;0;0.2;;;;;;;;;;;;;;;;;;;
-gms$s30_snv_scenario_target;;;;;;;;;;;;;2030;;;;;;;;;;;;2030;2030;2030;2030;2030;;;;;;;;;;;;;;;;;;;
+gms$s29_snv_shr;;;;0;0;0;0;0;0;0;0;0;0.2;;;;;;;0;;;;;0.2;0.2;0.2;0.2;0.2;;;;;;;;;;;;;;;;;;;
+gms$s29_snv_shr_noselect;;;;;;;;;;;;;;;;;;;;;;;;;0;0;0.2;0;0.2;;;;;;;;;;;;;;;;;;;
+gms$s29_snv_scenario_target;;;;;;;;;;;;;2030;;;;;;;;;;;;2030;2030;2030;2030;2030;;;;;;;;;;;;;;;;;;;
 gms$c31_grassl_yld_scenario;cc;nocc;nocc_hist;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 gms$s32_aff_plantation;;;;0;0;0;0;0;0;0;1;0;0;;;;;;;0;;;0;1;;;;;;;;;;;;;;;;;;;;;;;;
 gms$s32_aff_bii_coeff;;;;0;0;0;0;0;0;0;1;0;0;;;;;;;0;;;;;;;;;;;;;;;;;;;;;;;;;;;;

config/scenario_fsec.csv

@@ -26,13 +26,15 @@ gms$c15_food_scenario;;;SSP1;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 gms$c21_trade_liberalization;;;;;;;;;;;;;;;;;;;;;;;l908080r807070;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 gms$s21_trade_bal_damper;0.65;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 gms$c22_protect_scenario;;;;;;;;;;;;;;;;;;;;;;;;;;;;;BH_IFL;;;;;;;;;;;;;;;;;;;;;;
-gms$crop;penalty_apr22;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-gms$c30_rotation_scenario;default;;;;;;;;;;;;;;;;;;;;;;;;;;;agroecology;;;;;;;;;;;;;;;;;;;;;;;
+gms$croparea;detail_apr24;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+gms$c30_rotation_rules;FSEC;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+gms$c30_rotation_incentives;default;;;;;;;;;;;;;;;;;;;;;;;;;;;agroecology;;;;;;;;;;;;;;;;;;;;;;;
+gms$s30_implementation;0;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 gms$s30_rotation_scenario_target;2050;;;;;;;;;;;;;;;;;;;;;;;;;;;2050;;;;;;;;;;;;;;;;;;;;;;;
-gms$c30_marginal_land;q33_marginal;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+gms$c29_marginal_land;q33_marginal;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 gms$c30_bioen_water;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;rainfed;;;;;;;;;;;;;;;;;;;;;
-gms$s30_snv_scenario_target;;;;;;;;;;;;;;;;;;;;;;;;;;;2050;;;;;;;;;;;;;;;;;;;;;;;;
-gms$s30_snv_shr;;;;;;;;;;;;;;;;;;;;;;;;;;;0.2;;;;;;;;;;;;;;;;;;;;;;;;
+gms$s29_snv_scenario_target;;;;;;;;;;;;;;;;;;;;;;;;;;;2050;;;;;;;;;;;;;;;;;;;;;;;;
+gms$s29_snv_shr;;;;;;;;;;;;;;;;;;;;;;;;;;;0.2;;;;;;;;;;;;;;;;;;;;;;;;
 gms$past;endo_jun13;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 gms$c32_aff_policy;ndc;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 gms$c32_aff_mask;;;;;;;;;;;;;;;;;;;;;;;;;onlytropical;;;;;;;;;;;;;;;;;;;;;;;;;;

core/macros.gms

@@ -9,7 +9,7 @@
 
 * Macro for fixing a variable in the case that lower and upper bound are too
 * close to each other (closer than argument "sens")
-* EXAMPLE: ma_boundfix(vm_land,(j,"ifft"),up,10e-5);
+* EXAMPLE: ma_boundfix(vm_land,(j,"ifft"),up,1e-6);
 $macro m_boundfix(x,arg,sufx,sens) x.fx arg$(x.up arg-x.lo arg<sens) = x.sufx arg;
 
 $macro m_weightedmean(x,w,s) (sum(s,x*w)/sum(s,w))$(sum(s,w)>0) + 0$(sum(s,w)<=0);
@@ -97,12 +97,12 @@ $macro m_linear_cell_data_interpol(output,x,input_x1,input_x2,input_y1,input_y2)
 * macro for simple carbon stocks
 $macro m_carbon_stock(land,carbon_density,item) \
             (land(j2,item) * sum(ct,carbon_density(ct,j2,item,ag_pools)))$(sameas(stockType,"actual")) + \
-            (land(j2,item) * sum(ct,carbon_density(ct,j2,item,ag_pools)))$(sameas(stockType,"actualNoAcEst"));
+            (land(j2,item) * sum(ct,carbon_density(ct,j2,item,ag_pools)))$(sameas(stockType,"actualNoAcEst"))
 
 * macro for carbon stocks with age classes
 $macro m_carbon_stock_ac(land,carbon_density,sets,sets_sub) \
             sum((&&sets), land(j2,&&sets) * sum(ct, carbon_density(ct,j2,&&sets,ag_pools)))$(sameas(stockType,"actual")) + \
-            sum((&&sets_sub), land(j2,&&sets_sub) * sum(ct, carbon_density(ct,j2,&&sets_sub,ag_pools)))$(sameas(stockType,"actualNoAcEst"));
+            sum((&&sets_sub), land(j2,&&sets_sub) * sum(ct, carbon_density(ct,j2,&&sets_sub,ag_pools)))$(sameas(stockType,"actualNoAcEst"))
 
 * macros for peatland module
 $macro m58_LandMerge(land,landForestry,set) \

main.gms

@@ -249,7 +249,8 @@ $setglobal land_conservation  area_based_apr22
 
 $setglobal ageclass  feb21
 
-$setglobal crop  endo_apr21
+$setglobal cropland  simple_apr24
+$setglobal croparea  simple_apr24
 $setglobal past  endo_jun13
 
 $setglobal forestry  dynamic_feb21

modules/10_land/input/files

@@ -3,3 +3,5 @@ avl_land_t.cs3
 avl_land_t_0.5.mz
 luh2_side_layers.cs3
 avl_land_t_iso.cs3
+CroplandTreecover.cs2
+CroplandTreecover_0.5.mz

modules/10_land/landmatrix_dec18/declarations.gms

@@ -7,6 +7,7 @@
 
 parameters
  pm_land_start(j,land)         Land initialization area (mio. ha)
+ pm_land_hist(t_ini10,j,land)  Land area for historial time steps (mio. ha)
  pcm_land(j,land)              Land area in previous time step including possible changes after optimization (mio. ha)
 ;
 

modules/10_land/landmatrix_dec18/input.gms

@@ -14,6 +14,11 @@ $ondelim
 $include "./modules/10_land/input/avl_land_t.cs3"
 $offdelim
 ;
+*due to some rounding errors the input data currently may contain in some cases
+*very small, negative numbers. These numbers have to be set to 0 as area
+*cannot be smaller than 0!
+f10_land(t_ini10,j,land)$(f10_land(t_ini10,j,land)<0) = 0;
+
 
 table fm_luh2_side_layers(j,luh2_side_layers10) luh2 side layers (grid cell share)
 $ondelim

modules/10_land/landmatrix_dec18/presolve.gms

@@ -22,4 +22,4 @@ vm_lu_transitions.up(j,"primforest","primforest") = Inf;
 
 *' @stop
 
-m_boundfix(vm_land,(j,land),up,10e-5);
+m_boundfix(vm_land,(j,land),up,1e-6);

modules/10_land/landmatrix_dec18/start.gms

@@ -5,11 +5,8 @@
 *** |  MAgPIE License Exception, version 1.0 (see LICENSE file).
 *** |  Contact: [email protected]
 
-*due to some rounding errors the input data currently may contain in some cases
-*very small, negative numbers. These numbers have to be set to 0 as area
-*cannot be smaller than 0!
 pm_land_start(j,land) = f10_land("y1995",j,land);
-pm_land_start(j,land)$(pm_land_start(j,land)<0) = 0;
+pm_land_hist(t_ini10,j,land) = f10_land(t_ini10,j,land);
 
 pcm_land(j,land) = pm_land_start(j,land);
 vm_land.l(j,land) = pcm_land(j,land);