Increment and drain of growing stock

Updated: 1 Dec 2017
Next update: 2 Oct 2018

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 every year

Over the past 50 years, forest resources in Finland have increased every year, as the annual increment in the growing stock has exceeded the drain. The systematic measurement and monitoring of the volume of and increment in the growing stock started at the beginning of the 1920s with National Forest Inventories (NFI). Based on them, the annual increment in the growing stock on forest land and poorly productive forest land was fairly steady at around 55 million cubic metres until the end of the 1960s. The increment turned to strong growth at the start of the 1970s. Based on the first three measurement years of the 12th inventory (NFI12), the increment in the growing stock is 110 million cubic metres, which is double what it was 50 years ago. The mean increment per hectare in the country as a whole is 4.8 cubic metres.

The growth in the increment is mostly the result of draining peatland, improved silvicultural measures, and regeneration of old or otherwise poorly productive forests into productive young forests. Climate change has also had the effect of boosting the increment in the growing stock.

The volume of growing stock on forest land and poorly productive forest land was around 1,500 million cubic metres at the end of the 1960s. Based on the NFI12 measurements (2014 to 2016), the growing stock volume is 2,464 million cubic metres. Over the past 50 years, the volume of growing stock volume has increased by around one billion cubic metres and is now nearly 1.7 times what it was in the 1960s.

The main trend in the drain in Finland’s growing stock has also been upwards. In 2016, the drain reached a new record of nearly 86 million cubic metres. In 2000 to 2015, the average drain in the growing stock was 71 million cubic metres, of which private forests accounted for 83 per cent. The forest industry has cut the production capacity of the paper industry, in particular, but at the same time, the use of energywood in heating and power plants has increased.