Calculations were made for 130 years including five ten years and four twenty years periods. The results are reported only for the first 30-year period and the years beyond that era are for sustainability reasons.
In MELA2016 - program (Hirvelä et al. 2017) treewise basal-area growth models are calibrated using growth measurement data from 8th NFI. For calibration, growth measurements were adjusted with growth indices to the average level of diameter increment for years 1965–1994 (Henttonen 2000, Hynynen et al. 2002). For calculations presented here, tree basal-area growth models for forest land were calibrated using growth measurement data from 11th NFI. For calibration, growth measurements were adjusted with growth indices to the average level of diameter increment for years 1984–2013 (Korhonen et al. 2007). The calibration was done with sample trees from 11th NFI measured in years 2009–2013. Sample trees in a sample plot were accepted to calibration data if the sample plot was at forest land, the whole sample plot was in a single stand and no cuttings were recorded for the 10-year period before the measurement year (table 1).
The estimate of volume growth obtained using calibrated basal area growth was still adjusted using the realized average 30 year weather data for 1970–1999 (1999 is the middle year of the calibration period of 1984–2013) and 1988–2017 and transformation functions of Matala et al (2005). Those functions were used in order to predict the change in the growth as a function of the increases in mean air temperature and CO2 concentration between the long term averages of 1999 and 2017 which were in the Southern Finland 0.89 °C and 41.2 ppm and in the Northern Finland 0.996 °C and 41.2 ppm. By this way, the calculated estimate of volume growth for 2021–2030 was 104.0 million m3/year based on the scenario TH (the current harvesting levels during the years 2021–2023) while the volume growth for the whole country according to the NFI13 data measured in 2019–2023 was 103.0 million m3/year (Korhonen et al. 2024, Luke 2024b).
Table 1. Number and average basal area growths of NFI11 sample trees by soil types and tree species without and with the growth calibration.
| Soil type | Tree species | Sample trees n |
Basal area growth of NFI11 sample trees, cm2/5 years |
||
| Sample trees, corrected with indices |
Sample trees calculated using MELA2016 |
||||
| No calibration | Calibrated | ||||
| Mineral soils | |||||
| Pine | 17 592 | 42.1 | 41.6 | 43.9 | |
| Spruce | 11 958 | 50.7 | 57.2 | 52.4 | |
| Deciduous | 8 049 | 35.9 | 30.1 | 34.0 | |
| Total | 37 599 | 43.5 | 44.1 | 44.5 | |
| Undrained peatlands | |||||
| Pine | 785 | 24.8 | 8.5 | 18.1 | |
| Spruce | 557 | 28.0 | 17.2 | 23.3 | |
| Deciduous | 586 | 19.3 | 9.4 | 13.3 | |
| Total | 1 928 | 24.1 | 11.3 | 18.1 | |
| Drained peatlands | |||||
| Pine | 5 497 | 34.3 | 25.5 | 35.3 | |
| Spruce | 2 213 | 45.9 | 38.1 | 41.7 | |
| Deciduous | 2 933 | 26.4 | 22.1 | 23.8 | |
| Total | 10 643 | 34.5 | 27.2 | 33.4 | |
In MELA, stem volume (incl. bark) of an individual tree and the volumes of saw logs, pulpwood, energy stemwood and waste wood as solid cubic meters are obtained applying the taper curve models and volume functions of Laasasenaho (1982). Logs were bucked using the minimum log length of 4.3 meters and pulpwood using the minimum log length of 2.0 meters. The minimum top diameters (over bark) were 15 cm for pine logs, 16 cm for spruce logs and 18 cm for hardwood logs. Pine pulpwood was bucked up to the minimum top diameter of 6.3 cm. For other tree species, the minimum top diameter for pulpwood was 6.3 cm. The modeled saw log volumes are still reduced by the built-in log-volume reduction model of Mehtätalo (2002). This reduction is added to the pulpwood.
Waste wood includes stem parts of felled trees that are not hauled from the forest but are left in cuttings on the ground to decompose. Waste wood consists mostly of the non-commercial fractions of felled stems, i.e. parts of stems that do not fulfill the minimum Finnish timber assortment standards by size and quality for the industrial roundwood.
However, in practice the amount of waste wood in cuttings can differ from the model estimated due to the stump height, used minimum measures, defected stems or due to the commercial timber not hauled from forest. To reduce this gap the estimated proportion of waste wood in each cutting were calibrated by tree species, cutting methods and regions with NFI13 measurements (table 2), such that the percentage in each simulated cutting event in MELA matched up with NFI13 figures. The reduction was made only in pure industrial roundwood cuttings from pulpwood to waste wood when the estimated proportion of waste wood is lower than the corresponding proportion based on the NFI13 data in Table 2.
Table 2. Relative fractions of waste wood in NFI13 by tree species, cutting methods and regions, % of cutting drain (Räty 2024).
| Region | Tree species | Final cuttings | Other cuttings |
| Southern Finland | Pine | 1.6 | 3.9 |
| Spruce | 2.4 | 6.4 | |
| Deciduous | 7.6 | 11.9 | |
| Northern Finland | Pine | 2.4 | 4.1 |
| Spruce | 4.2 | 7.6 | |
| Deciduous | 12.9 | 14.6 |
The effects of the calibration of waste wood have been discussed in Luke (2024a) and Hirvelä et al. (2023).
A finite number of alternative management schedules were automatically simulated for NFI plots with MELA2016 (Hirvelä et al. 2017). Simulations were based on tree level natural process models for ingrowth, growth and mortality (e.g. Hynynen et al. 2002) and feasible (sound and acceptable) stand level management actions. Possible management actions were thinnings based either on number of trees or on basal area, final cuttings (clear cutting and seed tree cutting), preparation of regeneration areas, natural and artificial regeneration, and tending of young stands. Management actions were simulated when the criteria for current Finnish silvicultural guidelines (Äijälä et al. 2019) or the guidelines for energy wood logging (Koistinen et al. 2019) were satisfied. Regeneration was simulated when growing stock achieved either the minimum regeneration diameter based on 2-3 % revenue requirement or the minimum regeneration age.
Management actions were possible only on the forest land available for wood production. One or several management alternatives were simulated for all stands in the middle of each 10-year period and there was also always one simulated no-treatment alternative . For forest land with restricted availability for wood production only intermediate cuttings and tending of seedling stands were possible – final cuttings were not allowed. No management actions were allowed on protected forests and no cuttings were made on poorly productive forest land even if the wood production was allowed. Prescribed burning, drainage of new areas, fertilization, pruning and cuttings related to continuous cover forestry were not included in the management alternatives.
Industrial roundwood (saw logs and pulpwood) was possible to harvest from all intermediate cutting and final cutting areas. Energy wood (forest chips) was harvested either as logging residues (branches and tops) or as stumps with logging residues from final cutting areas on mineral soils. Only spruce stumps (with the stump diameter thicker than 35 cm) were lifted for energy use from spruce dominated stands. From thinning areas energy wood was possible to harvest as whole trees in separate loggings (no industrial roundwood harvested) or as trunks in separate loggings and in integrated loggings with industrial roundwood on mineral soils and drained peatlands. Energy wood harvesting was only possible when the total removal of energy wood at the stand-level was at least 40 m3 per hectare.
The calculations of forest greenhouse gas emission included the combined greenhouse gas balance of tree biomass and soil with respect to the net sequestration of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The greenhouse gas balances were calculated by region, with a positive balance indicating a net emission and a negative balance a net sink. The calculations fully follow the methods of the national greenhouse gas inventory ( Statistics Finland 2025), with the exception that the effects of harvested wood products or energy wood harvesting on greenhouse gas balances were not considered.
The net sequestration of carbon dioxide by growing forest biomass was calculated using the growth–drain method, in which the total removals of each ten-year period were subtracted from the corresponding total growth. The carbon content of growth and removals at a given point in time was estimated using tree-species-specific biomass models developed by Repola (2025, manuscript under peer review), assuming that the dry matter of tree biomass contains, on average, 50% carbon. The total carbon content of net growth was converted into the amount of carbon dioxide sequestered by living biomass (net sink) or released (net emission) using the molecular weight ratio of carbon dioxide to carbon (44/12).
Soil greenhouse gas calculations were carried out separately for mineral soils and drained peatlands only, as according to the national greenhouse gas inventory methodology (Statistics Finland 2025), undrained peatlands were assumed to produce no soil greenhouse gas emissions or removals. Calculations for mineral soils were conducted at the regional level using the Yasso07 model (Tuomi et al. 2011). Input data consisted of region-specific estimates of the total amounts of living biomass, natural mortality, and harvesting residues produced by the MELA calculations. These inputs were converted into biomasses using diameter-class-specific biomass expansion factors (BEFs) derived from the NFI13 dataset and, for living biomass, further converted into litter inputs using litter production coefficients applied in the national greenhouse gas inventory. Natural mortality and harvesting residues were entirely treated as litter inputs.
The initial state of regional soil carbon stocks was estimated using regional averages of litter inputs from living biomass, natural mortality, and harvesting residues calculated based on NFI12 and NFI13 data. In addition, average annual climate data (mean temperature, temperature amplitude, and precipitation) were calculated for each region starting from 1960 using historical meteorological observations from the Finnish Meteorological Institute (Venäläinen et al. 2005). The Yasso07 soil model was initialized using region-specific average climate data for the period 1960–1990 and average litter inputs for southern and northern Finland for the period 1970–1990. Projections of future changes in soil carbon stocks utilized, from 2021 onwards, the regional mean climate conditions for the period 2011–2021. Carbon amounts in soils were also converted to carbon dioxide equivalents using the ratio 44/12.
Estimates of carbon dioxide emissions from peatland soils were based on the method developed by Alm et al. (2023), which is specifically designed for determining CO2 emissions from drained peatlands. This method calculates CO2 emissions according to the following model: CO2Net = RHet - 44/12 * (IAGL+ IBGL+IAGR+IBGR), where RHet represents heterotrophic soil respiration; IAGL and IBGL are the annual carbon inputs from aboveground and belowground litter produced by tree biomass and ground vegetation; and IAGR and IBGR represent annual aboveground and belowground carbon inputs originating from harvesting residues and natural mortality. Key variables in the modelling include the species-specific mean basal areas of tree stands on drained peatlands by peatland forest type, as well as regional temperature data. The method is described in more detail in Alm et al. (2023).
Emissions of CH4 and N2O from soils of drained peatlands were calculated according to site area data, applying emission factors for organic soils from Ojanen et al. (2010, 2018) as used in the national greenhouse gas inventory (Statistics Finland 2022). In the calculation of the greenhouse gas balance, soil greenhouse gas emissions were converted into carbon dioxide equivalents using the 100-year global warming potentials (GWP100) from the IPCC Fifth Assessment Report (AR5): carbon dioxide 1, methane 28, and nitrous oxide 265.
These estimates were produced for the entire area of forest land and poorly productive forest land, assuming that no land-use changes occur during the calculation period. Consequently, potential land-use changes such as deforestation or afforestation were not considered.
The economic calculations concerning industrial roundwood (saw logs and pulpwood) were made using roadside prices, which were induced by adding harvesting costs on stumpage prices. Used stumpage prices for each region are based on the average realized unit prices in 2014-2023 (€/m3,table 3) by timber assortments deflated to the year 2023 (Luke 2024h, Database - Agriculture and fishing 2024). Average harvesting costs of saw logs and pulpwood are uniformly defined for the whole country according to the realized unit prices in 2014–2023 (€/m3, table 3) deflated to the year 2023 (Luke 2022b, Strandström 2024).
Table 3. Applied stumpage prices (€/m3) and harvesting costs (€/m3) used in defining road-side prices of industrial roundwood for different regions. Birch pulpwood prices were used for saw logs and pulpwood of aspen. For other broadleaved species, the prices were based on the stumpage prices of birch pulpwood in first thinnings which were on the average 5,00 €/m3 lower than the average price of birch pulpwood in all thinnings in the whole country.
| Stumpage price, €/m3 | ||||||
| Region | Saw log | Pulpwood | ||||
| Pine | Spruce | Birch | Pine | Spruce | Birch | |
| Uusimaa | 68.60 | 71.95 | 51.15 | 19.65 | 23.05 | 19.80 |
| Southwest Finland | 69.40 | 71.50 | 47.15 | 20.95 | 23.35 | 20.05 |
| Satakunta | 70.20 | 72.90 | 45.45 | 21.10 | 24.10 | 20.70 |
| Kanta-Häme | 69.45 | 72.55 | 50.85 | 20.25 | 23.40 | 20.35 |
| Pirkanmaa | 69.65 | 72.30 | 48.65 | 20.30 | 23.20 | 20.25 |
| Päijät-Häme | 70.55 | 72.65 | 53.35 | 20.85 | 23.25 | 20.50 |
| Kymenlaakso | 70.00 | 72.50 | 51.05 | 21.30 | 23.60 | 20.35 |
| South Carelia | 70.50 | 71.85 | 52.75 | 21.10 | 22.90 | 20.00 |
| South Savo | 70.00 | 71.35 | 55.70 | 21.30 | 22.80 | 20.50 |
| North Savo | 66.30 | 69.45 | 50.95 | 20.25 | 21.55 | 20.25 |
| North Carelia | 66.00 | 67.40 | 52.25 | 19.60 | 20.45 | 19.25 |
| Central Finland | 68.85 | 71.50 | 50.95 | 21.05 | 23.45 | 20.45 |
| South Ostrobothnia | 67.95 | 69.75 | 43.25 | 20.95 | 22.40 | 20.45 |
| Ostrobothnia | 67.60 | 68.95 | 41.00 | 20.45 | 22.00 | 20.25 |
| Central Ostrobothnia | 67.85 | 68.55 | 43.15 | 21.15 | 22.70 | 20.75 |
| North Ostrobothnia | 64.55 | 65.95 | 44.20 | 20.55 | 22.45 | 20.05 |
| Kainuu | 62.50 | 63.55 | 45.30 | 19.05 | 20.25 | 18.15 |
| Lapland | 58.85 | 57.35 | 15.65 | 19.35 | 20.10 | 17.95 |
| Åland | 43.50 | 43.50 | 36.30 | 16.60 | 16.60 | 11.00 |
| Region | Harvesting costs,€/m3 | |||||
| Saw log | Pulpwood | |||||
| Whole country | 9,30 | 16,90 | ||||
In the calculation of the variable ‘Gross stumpage income’, the stumpage prices of timber assortments were determined according to the average realized unit prices for the cutting methods (regeneration cuttings, thinnings and first thinnings) in 2014–2023 (Luke 2024h).
Stumpage prices for energy woodThe calculation of the variable ‘Gross stumpage income’ was based on the average realized stumpage prices (€/m3) in standing sales of energy wood in 2014–2023 in the whole country (Luke 2024g). In the calculation, the stumpage prices for energy wood were determined by the tree particles in accordance with Table 4. The average unit price of pruned stems was used for harvested roundwood, the unit price of logging residues for harvested branches (including also leaves and needles) and the unit price of stumps for harvested stumps and roots.
Table 4. The stumpage prices for energy wood (€/m3) applied for the whole country.
| Particle | Stumpage price, €/m3 |
| Roundwood | 6.70 |
| Branches | 4.60 |
| Stumps and roots | 2.40 |
Economic calculations with energy wood were based on the unit prices (€/Mwh) for forest chips at the mill yard according to the average realized prices in 2014–2023 deflated to the year 2023 in the whole country (Statistics: Energy prices 2024). The unit prices for Mwh were transformed to the unit prices of cubic meter (table 5) by multiplying them with 2. The same unit price was applied for all harvested energy wood.
Table 5. The mill yard prices of forest chips (€/m3) applied for the whole country.
| Particle | Price at the mill yard, €/m3 |
| Trunk | 55.60 |
| Branches | 55.60 |
| Stumps and roots | 55.60 |
The applied unit prices (€/h, table 6) used in estimating the logging costs of industrial roundwood (saw logs and pulpwood). Prices include wages, social costs, compensations for tools, profits of entrepreneurship.
Table 6. Unit prices (€/h) for industrial roundwood logging applied for the whole country.
| Task | Unit price, €/h |
| Forest haulage | 96.60 |
| Harvest | 123.20 | Manual logging | 34.45 |
The applied unit prices (€/h or €/m3, table 7) used in estimating the costs of energy wood procurement including logging, chipping and long-distance transportation. Prices include wages, social costs and compensations for tools. No subsidies for energy wood logging and chipping in young stand improvement thinnings were taken into account.
Table 7. Unit prices for energy wood procurement applied for the whole country.
| Task | Unit price |
| Forest haulage, €/h | 96.60 |
| Felling with harvester, €/h | 107.50 |
| Manual felling, €/h | 34.45 |
| Stump lifting with excavator, €/h | 107.50 |
| Compensation of felling logging residues in to the piles, €/m3 | 0.57 |
| Mobile chipper at the road side, €/h | 260.00 |
| Long-distance transport with trucks, €/h | 90.00 |
| Costs of loading and unloading of trucks, €/h | 55.00 |
| Fixed stationary crusher, €/m3 | 3.50 |
Unit prices for silvicultural tasks (table 8) are calculated as the average realized prices in 2014-2023 by tasks (Luke 2024d) deflated to the year 2023 by districts.
Table 8. Applied unit prices of silvicultural work (€/ha, €/h or €/plant).
| Task | Southern Finland | Middle Finland | Ostrobothnia region | Northern Finland | |
| Harrowing and scarification, €/ha | 410.00 | 365.00 | 321.00 | 245.00 | |
| Ploughing and mounding, €/ha | 526.00 | 506.00 | 494.00 | 406.00 | |
| Cost on pine seeds, €/ha | 230.00 | 240.00 | 260.00 | 230.00 | |
| Pine seedling, €/plant | 0.19 | 0.19 | 0.19 | 0.19 | |
| Spruce seedling, €/plant | 0.22 | 0.22 | 0.22 | 0.22 | |
| Birch seedling, €/plant | 0.38 | 0.38 | 0.38 | 0.38 | |
| Supplementary pine seedling, €/plant | 0.23 | 0.23 | 0.23 | 0.23 | |
| Supplementary spruce seedling, €/plant | 0.33 | 0.33 | 0.33 | 0.33 | |
| Supplementary birch seedling, €/plant | 0.51 | 0.51 | 0.51 | 0.51 | |
| Silvicultural work, €/h | 25.40 | 25.40 | 25.40 | 25.40 | |
| Prevention of grass, €/ha | 455.00 | 455.00 | 446.00 | 367.00 | |
| Clearing and tending, €/h | 34.45 | 34.45 | 34.45 | 34.45 | |
| Supplementary drainage, €/ha | 293.00 | 241.00 | 336.00 | 238.00 | |
| Planning and supervision, €/h | 25.40 | 25.40 | 25.40 | 25.40 |
Districts and their constituent regions used here:
Southern Finland: regions 1–10
(Uusimaa, Southwest Finland, Satakunta, Kanta-Häme, Pirkanmaa,
Päijät-Häme, Kymenlaakso, South Karelia and South Savo) and 21 (Åland)
Middle Finland: regions 11–13 (North Savo, North Karelia and Central Finland)
Ostrobothnia region: regions 14–16 (South Ostrobothnia, Ostrobothnia and Central Ostrobothnia)
Northern Finland: regions 17–19 (North Ostrobothnia, Kainuu and Lapland)