Increment and drain of growing stock

Updated: 17 Oct 2018
Next update: 17 Oct 2019

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.

Sources

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

   

Forest resources increasing each year

Over the past 50 years, forest resources have increased every year when the annual increment of the growing stock has exceeded the drain (fellings). The systematic measurement and monitoring of the volume and increment of the growing stock started at the beginning of the 1920s in national forest inventories (NFI). Based on them, the annual increment of the growing stock on forest land and on poorly productive forest land was fairly evenly at around 55 million cubic metres until the end of 1960s. The increment turned to a strong growth at the turn of the 1960s and 1970s. Based on the 12th inventory (measurement years 2014 to 2017), the current increment of the growing stock amounts to 107.0 million cubic metres, which is nearly double compared to 50 years ago. Mean annual increment per hectare in the whole country is 4.7 cubic metres.

The upturn in increment has been mostly affected by peatland drainage, improved silvicultural measures and renewal of low-yielding forests into productive young forests. Climate change has also had a rising effect on the increment of growing stock.

The growing stock volume on forest land and on poorly productive forest land was around 1,500 million cubic metres at the end of the 1960s. Based on the NFI12 measurements (2014 to 2017), the growing stock volume is 2,473 million cubic metres. 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 2017, the drain reached a new high of 87 million cubic metres. During 2000−2016, the average drain of the growing stock was 72 million cubic metres, of which the share of private forests was 83 per cent. In recent years, the forest industry has particularly invested in pulp and paperboard capacity. Energy use of wood is also at a record level.