Forests are often called the lungs of the Earth – for a good reason. Trees produce oxygen and bind carbon dioxide. Growing forests absorb carbon from the atmosphere, storing it in wood biomass. When trees are harvested, carbon is transferred to wood-based products. At the end of the product’s lifecycle, the carbon is released into the atmosphere for new generations of trees to absorb. In order to sustain this cycle, a new tree has to be planted to replace every harvested one. Sustainably managed forests act as a carbon sink while yielding raw material to replace fossil resources.
We mitigate and adapt to climate change
Our climate commitment
-65%
Reduction of our own CO2 emissions
-30%
Reduction of our supply chain CO2 emissions
Pioneer climate-positive products
Keep forests as carbon sinks
Sustainably managed forests are carbon sinks
We plant 55 million seedlings per year. On average, this means more than 100 trees every minute, year-round. Forest regeneration after harvesting is the cornerstone of our sustainable forest management approach. Our actions do not result in any deforestation.
We carefully plan our harvesting rates to ensure that our forestry practices are fully sustainable. In short, we plant more trees than we harvest, and safeguard valuable habitats.
We manage our forests to help them serve as carbon sinks. We conduct ongoing research with expert partners to better understand and identify the climate impact of our forests.
Read more: UPM deepens the scientific knowledge on its products’ climate impacts
Finland: Sink = trees increment - drainage (harvesting and natural) + soil sink (using Yasso07). Uruguay: Sink = change in tree carbon stock + soil sink (using Yasso07). USA: Source = change in tree carbon stock. We aim to constantly improve and harmonise methodologies and make calculations more accueate. In 2023, soil carbon models were improved for Uruguay with actual measurements. The previous year's figure is therefore not fully comparable
Carbon sink calculations in Finland,
the Unites States of America and Uruguay
The Natural Resources Institute Finland (LUKE) calculates the carbon sink of our own and leased forests and tree plantations in Finland, the USA and Uruguay. The results are reported annually as a five-year average and the calculation is developed as best practice evolves.
Changes in forest carbon stocks cover both the tree stock and the soil. Long-term measurement data and mathematical modelling from the Natural Resources Institute Finland have been used in the calculation. Changes in the carbon stock of the stand are calculated as the difference between annual growth and depletion. The calculation has been performed separately for forests growing on mineral soils and peat soils. Estimates of stand growth is based on the National Forest Inventory (VMI), which is a five-year inventory cycle. Growth figures from the VMI for the period 2014-2018 have been used in the calculation, where growth represents the average growth of the past five-year period before the measurement. The VMI calculations were performed on plots on UPM's land and included forest and fallow land. Logging volumes and their allocation to mineral and peat soils are obtained from UPM statistics. Logging volumes from previous years have been scaled to the current forestland area to allow comparison. To the amount of wood removed by logging, an estimate of the natural loss has been added, based on average figures for southern Finland as calculated by the VMI.
In mineral soils, changes in soil carbon stocks have been calculated using the Yasso07 model (Tuomi et al. 2011, en.ilmatieteenlaitos.fi/yasso), which describes the decomposition of soil litter and the resulting release of carbon dioxide. The input to the model calculation is the calculated litter input to the soil from tree data, and weather data that influence the decomposition rate. For drained peatlands, the soil greenhouse gas inventory balance has been calculated using the emission factors (eg. Statistics Finland 2021) and the area used in the greenhouse gas inventory. The emission factors are based on a large data set of measurements taken in different locations in Finland and on published studies. The emission factors vary according to site, peatland type and drainage conditions. Emissions of carbon dioxide, methane and nitrogen dioxide from drained peatlands have been recalculated to reflect the greenhouse gas impact of carbon dioxide. Soil carbon stocks change slowly. Therefore, unlike tree data, the soil inventory is updated every few years.
References:
Natural Resources Institute Finland VMI (in Finnish): https://www.luke.fi/tietoa-luonnonvaroista/metsa/metsavarat-ja-metsasuunnittelu/metsavarat/
Tuomi, M., Laiho, R., Repo, A., & Liski. J. 2011. Wood decomposition model for boreal forests. Ecological Modelling 222 (3): 709-718. doi:10.1016/j.ecolmodel.2010.10.025
Statistics Finland 2021: National Inventory Report (NIR) https://unfccc.int/documents/271571
Carbon sinks on UPM-owned forests in the USA were calculated as the difference in carbon stored in growing stock between two time points in 5 years. The calculation complied with IPCC guidelines and was based on available data on annual totals of stem volumes by age classes.
The total biomass carbon stock change was based on species-specific wood densities (Wood database) and species group-specific biomass expansion factors (IPCC guidelines). The wood database was used because IPCC categories do not cover all tree species growing in UPM forests.
To convert expanding merchantable stem volume to above-ground biomass, we merged growing stock levels (m3) to correspond to the groupings appearing in IPCC guidelines. The age classes were merged to group levels of m3 in five groups. We summed these groups as per species groups in line with existing BCEFs (biomass carbon expansion factors) (hardwoods, pines, conifers, other) on a per-year basis. The group “other” was presumed to have average BCEFs (biomass carbon expansion factors) for hardwoods, pines, and conifers. The calculated species groups’ above-ground biomasses were converted to carbon using constants appearing in table 4.3 in the IPCC guidelines.
The below-ground tree biomass was calculated based on ratios between above-ground and below-ground biomasses for specific species groups in compliance with IPCC guidelines (Table 4.4.). Annual above- and below-ground forest carbon sinks were summed up per year and converted to CO2 by multiplying by the ratio of the molecular weight (44/12 from C to CO2). The difference between each year was then calculated. Currently soil carbon stock is not included in the calculations.
Literature:
Wood database: https://www.wood-database.com/
IPCC guidelines Volume 4: https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol4.html
The change in the carbon stock of a stand, for example, the carbon sink of the stand, is based on the annual change in the carbon stock per tree. The calculation is based on the IPCC guidelines/calculation method and annual, stand-specific stand volume and area changes obtained by UPM. The bark fraction has been calculated based on the trunk volume according to a model developed by UPM. Volume has been converted to biomass using species-specific wood density and IPCC conversion factors (IPCC guidelines, Table 3A.1.10). The carbon content in the dry matter is estimated at 50% and the carbon is converted to carbon dioxide by a factor of 44/12. All the planted Eucalyptus species are included in the calculation.
The change in soil carbon stock has been calculated using the dynamic Yasso07 soil model (Tuomi et al. 2011, en.ilmatieteenlaitos.fi/yasso), which calculates changes in soil carbon in the surface layer (up to 1 m). The calculation of the model is based on the amount and quality of litter input and local weather conditions. We are currently developing the soil carbon calculation method with a project by Natural Resources Institute Finland.
The litter input is estimated retrospectively for each particular pattern over the lifetime of the individual pattern. The volume of stands in previous rotations has been calculated based on species-specific growth curves prepared by UPM. The assumed life of the plantation is based on the average rotation period of the stand (11 years) and the assumed number of rotations. The amount and quality of stand-specific litter input has been calculated separately for tree parts (trunk, bark, leaves, branches, dead roots and fine roots) using species-specific and general conversion factors. The amount of soil carbon calculated by the model has been converted to carbon dioxide by a factor of 44/12. Data on daily temperatures and precipitation are obtained from five meteorological stations operated by the National Agricultural Research Institute of Uruguay (INIA) located throughout the country.
Both stand and soil calculations have been carried out separately for eucalyptus plantations owned and leased by UPM. The annual carbon sink is expressed as the sum of the individual carbon sink values.
Literature references:
IPCC guidelines Volume 4: https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol4.html
Tuomi, M., Laiho, R., Repo, A., & Liski. J. 2011. Wood decomposition model for boreal forests. Ecological Modelling 222 (3): 709-718. doi:10.1016/j.ecolmodel.2010.10.025
Replacing fossils with wood-based products
Wood has enormous potential as a renewable, recyclable and carbon-neutral raw material. We foresee an exciting future for innovative wood-based products in the post-fossil era.
Sustainable wood-based products start with sound forestry practices. Our forests serve as carbon sinks thanks to our sustainable harvesting and systematic forest regeneration policy. A forest’s total carbon sequestering capacity also includes the carbon contained in the soil. Finland’s peatlands, for instance, are massive carbon storages. Protecting natural peatlands is therefore important both for the climate and for biodiversity.
Reforestation and afforestation of degraded land is an effective way to increase the total carbon sequestration capacity of forests. Our plantations in Uruguay show a significant increase in carbon sequestration compared to modified natural grassland reference areas.
The efficient use of wood raw material is an important factor affecting the carbon footprint of wood-based products. We maximize the usage of harvested wood by harnessing by-products and side streams. A great example is our renewable diesel made of crude tall oil, which is a by-product of pulp manufacturing.
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