%0 Research article
%T Upper stem diameter and volume prediction strategies in the National Forest Inventory of Finland
%A Stenman, Virpi
%A Kangas, Annika
%A Holopainen, Markus
%D 2023
%J Silva Fennica
%V 57
%N 3
%R doi:10.14214/sf.23021
%U https://silvafennica.fi/article/23021
%X In forest inventories, field data are needed for the prediction of tree volumes. However, gathering field data requires resources, such as labour, equipment, and data management operations. This means that time and budget, as well as quality, must be carefully considered when National Forest Inventory (NFI) field measurement activities are planned. Therefore, the development of cost efficient, simple, safe and reliable measurement methods and tools are of great interest. To date, upper stem diameter (<i>d6</i>), which provides a more reliable estimation of tree stem volume, has typically been measured with a parabolic calliper. In this study, the performance of the Criterion laser-based dendrometer was examined for <i>d6</i> measurements. A total of 326 sample trees were measured multiple times with three different measurement instruments. These instruments were used to measure diameter at breast height (<i>dbh</i>) as well as <i>d6</i> measurements. Bland-Altman plots and measurement error variances were used to determine measurement instrument reliability. For all trees, the standard deviation for the laser based dendrometer was 18.73 mm at <i>dbh</i> and 15.36 mm for the <i>d6</i> measurements. When the performance of Criterion was analysed with reference to the mean value of repeated measurements, the standard deviation in the <i>dbh</i> measurements was 12.21 mm, and 8.88 mm in the <i>d6</i> measurements.