This module handles the production of timber using plantations 32_forestry and natural vegetation 35_natveg. Timber can be produced from both commercial plantations and natural forests. The module feeds vm_prod at cluster level to 17_production and 21_trade modules. This module also calculates the “real” harvested area in natural forests i.e. vm_hvarea_primforest,vm_hvarea_secdforest and v73_hvarea_other.
| Description | Unit | A | |
|---|---|---|---|
| im_gdp_pc_ppp_iso (t_all, iso) |
Per capita income in purchasing power parity | \(USD_{05PPP}/cap/yr\) | x |
| im_pop_iso (t_all, iso) |
Population | \(10^6/yr\) | x |
| pm_representative_rotation (t_all, i) |
Representative regional rotation | \(1\) | x |
| pm_timber_yield (t, j, ac, forest_land) |
Forest growing stock | \(m3/ha/yr\) | x |
| sm_fix_SSP2 | year until which all parameters are fixed to SSP2 values | \(year\) | x |
| vm_hvarea_forestry (j, ac) |
Harvested area from timber plantations | \(10^6 ha\) | x |
| vm_hvarea_other (j, ac) |
Harvested area from other land | \(10^6 ha\) | x |
| vm_hvarea_primforest (j) |
Harvested area from primary forest | \(10^6 ha\) | x |
| vm_hvarea_secdforest (j, ac) |
Harvested area from secondary forest | \(10^6 ha\) | x |
| vm_prod (j, k) |
Production in each cell | \(10^6 tDM/yr\) | x |
| Description | Unit | |
|---|---|---|
| pm_demand_ext (t_ext, i, kforestry) |
Extended demand for timber beyound simulation | \(10^6 tDM/yr\) |
| pm_demand_forestry_future (i, kforestry) |
Future forestry demand in current time step | \(tDM/yr\) |
| vm_cost_timber (i) |
Actual cost of harvesting timber from forests | \(10^6 USD/yr\) |
biomass_mar20 realization acts as a common tunnel for land related decisions in forestry 32_forestry and natveg 35_natveg modules and corresponding production of woody biomass realized. This realization harvests timber from available plantations to meet a portion of overall timber demand. Rest of the timber production comes by harvesting natural vegetation. Aggregated timber demand for wood and woodfuel is calculated based on demand equation from Lauri et al. (2019) and income elasticities from Morland et al. (2018). The timber demand calculated is further adjusted between the solve steps where if the model sees no way of producing timber from existing resources, the demand is lowered down to an extent that an adjusted level of demand can be met with resources at hand.
Timber production cost covering cost of harvest as well as the cost incurred by utilizing free variable with a very high cost. Ideally this free variable is only used when there is no other way to meet timber demand. To make sure that timber plantations are harvested at rotation age, the economically optimal point in time, we assume zero costs for production from timber plantations, and higher costs for for production from natural vegetation.
\[\begin{multline*} vm\_cost\_timber(i2) = v73\_cost\_hvarea(i2) + \sum_{cell(i2,j2),land\_natveg,ac,kforestry}\left( v73\_prod\_natveg(j2,land\_natveg,ac,kforestry) \cdot s73\_timber\_harvest\_cost\right) + \sum_{cell(i2,j2),kforestry}\left( v73\_prod\_heaven\_timber(j2,kforestry) \cdot s73\_free\_prod\_cost\right) \end{multline*}\]
Harvested cost is defined as the cost incurred while removing biomass from forests. Harvestig natural vegetation is made less attractive to the model by providing higher harvesting costs. This is to mimic the difficulties in accessing primary and secondary forests.
\[\begin{multline*} v73\_cost\_hvarea(i2) = \sum_{ct,cell(i2,j2),ac\_sub}\left( vm\_hvarea\_forestry(j2,ac\_sub) \cdot s73\_timber\_harvest\_cost\right) + \sum_{ct,cell(i2,j2),ac\_sub}\left( vm\_hvarea\_secdforest(j2,ac\_sub) \cdot s73\_timber\_harvest\_cost \cdot p73\_cost\_multiplier("secdforest")\right) + \sum_{ct,cell(i2,j2),ac\_sub}\left( vm\_hvarea\_other\left(j2, ac\_sub\right) \cdot s73\_timber\_harvest\_cost \cdot p73\_cost\_multiplier("other")\right) + \sum_{ct,cell(i2,j2)}\left( vm\_hvarea\_primforest(j2) \cdot s73\_timber\_harvest\_cost \cdot p73\_cost\_multiplier("primforest")\right) \end{multline*}\]
The following equation describes cellular level production (in dry matter) of woody biomass vm_prod_reg as the sum of the cluster level production of timber coming from ‘v73_prod_forestry’ and ‘v73_prod_natveg’.
\[\begin{multline*} vm\_prod(j2,kforestry) = \sum_{ac\_sub} v73\_prod\_forestry(j2,ac\_sub,kforestry) + \sum_{land\_natveg,ac\_sub}v73\_prod\_natveg(j2,land\_natveg,ac\_sub,kforestry) + v73\_prod\_heaven\_timber(j2,kforestry) \end{multline*}\]
Woody biomass production from timber plantations is calculated by multiplying the area under production with corresponding yields of plantation forests, divided by the timestep length.
\[\begin{multline*} \sum_{kforestry} v73\_prod\_forestry(j2,ac\_sub,kforestry) = vm\_hvarea\_forestry(j2,ac\_sub) \cdot \frac{ \sum_{ct} pm\_timber\_yield(ct,j2,ac\_sub,"forestry") }{ m\_timestep\_length\_forestry} \end{multline*}\]
Woody biomass production from secondary forests is calculated by multiplying the area under production with corresponding yields of secondary forests, divided by the timestep length.
\[\begin{multline*} \sum_{kforestry} v73\_prod\_natveg(j2,"secdforest",ac\_sub,kforestry) = vm\_hvarea\_secdforest(j2,ac\_sub) \cdot \frac{ \sum_{ct}pm\_timber\_yield(ct,j2,ac\_sub,"secdforest") }{ m\_timestep\_length\_forestry} \end{multline*}\]
Woody biomass production from primary forests is calculated by multiplying the area under production with corresponding yields of primary forests, divided by the timestep length.
\[\begin{multline*} \sum_{kforestry} v73\_prod\_natveg(j2,"primforest","acx",kforestry) = vm\_hvarea\_primforest(j2) \cdot \frac{ \sum_{ct} pm\_timber\_yield(ct,j2,"acx","primforest") }{ m\_timestep\_length\_forestry} \end{multline*}\]
Wood-fuel production from other land is calculated by multiplying the area under production with corresponding yields of other land, divided by the timestep length. Wood production from other landis not allowed.
\[\begin{multline*} v73\_prod\_natveg(j2,"other",ac\_sub,"woodfuel") = vm\_hvarea\_other(j2,ac\_sub) \cdot \frac{ \sum_{ct} pm\_timber\_yield(ct,j2,ac\_sub,"other") }{ m\_timestep\_length\_forestry } \end{multline*}\]
Limitations Timber demand cannot be determined endogenously
| Description | Unit | A | |
|---|---|---|---|
| f73_income_elasticity (total_wood_products) |
Income elasticities of wood products | \(1\) | x |
| f73_prod_specific_timber (t_past, iso, total_wood_products) |
End use timber product demand | \(10^6 m3/yr\) | x |
| f73_volumetric_conversion (kforestry) |
Income elasticities of wood products | \(1\) | x |
| p73_cost_multiplier (land_natveg) |
Cost multiplier for natural vegetation to make harvests expensive by a factor | \(1\) | x |
| p73_criterion | Criteria calculating timber demand adjustment | \(10^6 tDM/yr\) | x |
| p73_demand_ext_original (t_ext, i, kforestry) |
Original prescribed timber demand | \(10^6 tDM/yr\) | x |
| p73_forestry_demand_prod_specific (t_all, iso, total_wood_products) |
End product specific timber demand | \(10^6 m3/yr\) | x |
| p73_timber_adjustment_ratio (t, i, kforestry) |
Ratio between adjusted and prescribed timber demand | \(1\) | x |
| p73_timber_demand_gdp_pop (t_all, i, kforestry) |
Timber demand based on lauri et al 2019 | \(10^6 m3/yr\) | x |
| p73_timber_harvest_cost (t, j, ac, forest_land) |
Harvesting costs as a function of carbon density | \(USD/ac/ha\) | x |
| q73_cost_hvarea (i) |
Cost of harvesting timber from forests | \(10^6 USD/yr\) | x |
| q73_cost_timber (i) |
Actual cost of harvesting timber from forests | \(10^6 USD/yr\) | x |
| q73_prod_forestry (j, ac) |
Production of woody biomass from commercial plantations | \(10^6 tDM/yr\) | x |
| q73_prod_other (j, ac) |
Production of woody biomass from other land | \(10^6 tDM/yr\) | x |
| q73_prod_primforest (j) |
Production of woody biomass from primary forests | \(10^6 tDM/yr\) | x |
| q73_prod_secdforest (j, ac) |
Production of woody biomass from secondary forests | \(10^6 tDM/yr\) | x |
| q73_prod_timber (j, kforestry) |
Production of woody biomass from commercial plantations and natural vegetation | \(10^6 tDM/yr\) | x |
| s73_cost_multiplier | Multiplier for expensive harvest in natural vegetation | \(1\) | x |
| s73_demand_switch | Logical switch to turn on or off timber demand 1=on 0=off | \(1\) | x |
| s73_foresight | Boolean switch for establishment demand assumption 1=forward looking 0=myopic | \(1\) | x |
| s73_free_prod_cost | Very high cost for using non existing land for plantation establishment | \(USD/tDM\) | x |
| s73_timber_harvest_cost | Cost for harvesting timber | \(USD/ha\) | x |
| s73_timber_prod_cost | Cost for produccing a unit of timber | \(USD/tDM\) | x |
| v73_cost_hvarea (i) |
Cost of harvesting timber from forests | \(10^6 USD/yr\) | x |
| v73_prod_forestry (j, ac, kforestry) |
Production of woody biomass from commercial plantations | \(10^6 tDM/yr\) | x |
| v73_prod_heaven_timber (j, kforestry) |
Production of woody biomass from heaven | \(10^6 tDM/yr\) | x |
| v73_prod_natveg (j, land_natveg, ac, kforestry) |
Production of woody biomass from natural vegetation | \(10^6 tDM/yr\) | x |
| description | |
|---|---|
| ac | Age classes |
| ac_est(ac) | Dynamic subset of age classes for establishment |
| ac_sub(ac) | Dynamic subset of age classes excluding establishment |
| cell(i, j) | number of LPJ cells per region i |
| ct(t) | Current time period |
| forest_land(land) | land from which timber can be taken away |
| i | all economic regions |
| i_to_iso(i, iso) | mapping regions to iso countries |
| i2(i) | World regions (dynamic set) |
| iso | list of iso countries |
| j | number of LPJ cells |
| j2(j) | Spatial Clusters (dynamic set) |
| k(kall) | Primary products |
| kforestry_to_woodprod(kforestry, total_wood_products) | Mapping between intermediate and end use wood products |
| kforestry(k) | forestry products |
| land | Land pools |
| land_natveg(forest_land) | Natural vegetation land pools |
| t_all(t_ext) | 5-year time periods |
| t_ext | 5-year time periods |
| t_past(t_all) | Timesteps with observed data |
| t(t_all) | Simulated time periods |
| total_wood_products | End use wood product category from FAO |
| type | GAMS variable attribute used for the output |
| wood_panels(wood_products) | Wood products used for panels construction |
| wood_products(total_wood_products) | Major 2nd level products from wood processing |
Abhijeet Mishra, Florian Humpenöder
09_drivers, 11_costs, 14_yields, 16_demand, 17_production, 32_forestry, 35_natveg
Lauri, Pekka, Nicklas Forsell, Mykola Gusti, Anu Korosuo, Petr Havlík, and Michael Obersteiner. 2019. “Global Woody Biomass Harvest Volumes and Forest Area Use Under Different Ssp-Rcp Scenarios.” Journal of Forest Economics 34 (3-4): 285–309. https://doi.org/10.1561/112.00000504.
Morland, Christian, Franziska Schier, Niels Janzen, and Holger Weimar. 2018. “Supply and Demand Functions for Global Wood Markets: Specification and Plausibility Testing of Econometric Models Within the Global Forest Sector.” Forest Policy and Economics 92: 92–105.