Increment and drain of growing stock

Updated: 3 Dec 2020
Next update: 30 Nov 2021

Comparison of the growing stock increment and drain (forest balance) shows whether the stemwood stock in forests is growing, remains unchanged or is decreasing. The volume is expressed in millions of solid cubic metres with bark.

The latest data on the growing stock increment are based on the National Forest Inventory (NFI12, measurement years 2014−2016), performed by the Natural Resources Institute Finland. The Finnish Forest Research Institute started the National Forest Inventories at the beginning of the 1920s. The NFI data are sample data that cover the entire country. According to the current system, each inventory measures around 53,000 sample plots and about one million trees on forest land and poorly productive forest land over a five-year period.

The estimate of the drain in the growing stock was based on wood consumption studies until 1984, and since then has used annual removal and wood consumption statistics. In addition to felled stemwood, the drain in the growing stock drain also includes stemwood waste left in forests, and natural losses.


Natural Resources Institute Finland: National Forest Inventory (NFI) and Statistical Services


Timber reserves increasing each year

Over the past 50 years, the timber reserves in forests have increased every year when the annual increase in the growing stock has been bigger than the drain. The systematic measurement and monitoring of the volume and increase of the growing stock started at the beginning of the 1920s by National Forest Inventories (NFI). Based on them, the annual increase in the growing stock in forest land and forest land of low productivity was fairly evenly at around 55 million cubic metres until the end of 1960s. The increase turned to a strong growth at the turn of the 1960s and 1970s. Based on the 12th inventory (measurement years 2014 to 2018), the increase in the growing stock is 108 million cubic metres, which is nearly double compared to 50 years ago. Average growth per hectare in the whole country is 4.7 cubic metres.

The increase in growth has been mostly affected by peatland drainage, improved forestry and renewal of old or otherwise underproductive forests into productive young forests. Climate change has also had a rising effect on the increase in the growing stock.

The growing stock volume in forest land and forest land of low productivity was around 1,500 million cubic metres at the end of the 1960s. Based on the NFI12 measurements (2014 to 2018), the growing stock volume is 2,475 million cubic metres, of which 90 per cent is located on land available for wood production.

Over the past 50 years, the growing stock volume has increased by around one billion cubic metres and is now nearly 1.7-fold compared to the 1960s.

The main trend in the drain of Finland’s growing stock has also been upwards. In 2018, the drain reached a new high of 94 million cubic metres. In 2014 to 2018, the average drain of the growing stock was close on 86 million cubic metres, of which the share of private forests was 84 per cent. The forest industry experienced a peak in 2018, and the industry has in recent years invested especially in increasing the pulp and paperboard capacity. Energy use of wood is also at a record level.