New conversion factor results in slightly reduced gross felling

Nyhet | Statistik - 05 December 2022

The conversion factor used for the calculation of the annual felling statistics will be slightly adjusted. The adjustment is made after a study that the Swedish Forest Agency has carried out together with the Forestry Research Institute of Sweden (Skogforsk) as part of the work to continuously improve the quality of the statistics. The adjustment will also mean that the statistics for gross felling will decrease slightly.

The conversion factor is used between cubic meters solid volume under bark (m³s ub) and cubic meters standing volume (m³sk) and is used for the calculation of the annual felling statistics. The factor is of great importance for the quality of the statistics. The study suggests that the existing conversion factor of 1.2 should be revised to 1.188. This means that the gross felling is reduced by 1 per cent.

The official felling statistics are based on annual data on roundwood consumption, stock changes and import and export data. Based on these statistical data, the Swedish Forest Agency calculates the annual felling in m3s ub.

To calculate felling in m3sk, the Swedish Forest Agency uses the conversion factor 1.2, which was developed in the 1970s. Since then, there have been changes that have been deemed to have an impact on the conversion factor. In addition, the data sources needed to calculate the conversion factor have been improved. For the quality of the statistics, it is important that the conversion factor is correct

In a joint study, Skogforsk and the Swedish Forest Agency have analyzed factors that affect the conversion factor and calculated a new conversion factor based mainly on harvester data and supplementary data on the composition of the felling from the Swedish National Forest Inventory. The recently published study suggests a revision of the current conversion factor to 1.188.

– The new conversion factor differs from the one used so far, but the difference is not so big as we might have expected. We will use the new conversion factor in future publications, but the change doesn’t mean any big revisions of the felling statistics. This says Jonas Paulsson, statistician at the Swedish Forest Agency.

For the Swedish Forest Agency's felling calculation, the new conversion factor means that the gross felling level for year 2021 will decrease by 1 per cent, corresponding to 0.9 million m³sk.

Whether the adjustment will also apply to statistics going back in time has not yet been decided.

Explanation

Felling in cubic meters standing volume (m³sk): The trunk volume above the stump including tree top and bark but excluding branches.

Felling in cubic meters solid volume under bark (m³s ub): Total harvested trunk volume above the stump excluding, treetops, bark, not removed felled whole trees and not removed trunk parts.