Sample tree data from the Swedish NFI used in
Jacobsson, Jonas, Fridman, Jonas, Axelsson, Anna-Lena, Milberg, Per (2025). An aging population? A century of change among Swedish forest trees. Forest Ecology and Management. 580:122509. https://doi.org/10.1016/j.foreco.2025.122509

Contact: Jonas Fridman, riksskogstaxeringen@slu.se

Column                         Description
Year of Inventory              Year of Inventory
ClusterID                      Unique cluster ID
PlotID                         Unique plot ID within cluster ID
Landuse_code                   Landuse code (see below)
Landuse_char                   Landuse classification in text (see below)
Region                         Region used for analysis in publication: Norrbotten, South-central Sweden (SC Sweden), Rest of Sweden, see below.
Within_formally_protected_areas0=No, 1= Yes. According to status 2023.
Diameter (mm)                  Diameter at breast height (mm)
Stem_volume (m3)               Stem volume (m3)
Age_breast_height              Tree age at 1.3 m (yrs)
Total_tree_age                 Total tree age (yrs)
No_stems_exp_factor            Expansion factor for the estimate of total number of stems (within period)
Volume_m3_exp_factor           Expansion factor for the estimate of total volume of stems (within period)
Species_code                   Species code
Species_latin                  Species name in latin
Species_group                  Species group: Pine, Spruce, Deciduous
Period                         1926 (Inventory years 1923-1929), 1957 (1953-1962), 1987 (1983-1992), 2017 (2013-2022)


Landuse_code                   Landuse_char
1                              Productive forestland
4                              Mire
6                              Sub-alpine spruce forest
5                              Rockland
3                              Agricultural land
9                              Other land
2                              Agricultural land
14                             Other land
10                             Other land
8                              Other land
20                             Other land

Region                         Description
Norrbotten                     County of Norrbotten
SC Sweden                      South-central Sweden. Include counties; Västra Götaland, Östergötland, Jönköping, Kalmar and Kronoberg
Rest of Sweden                 All other Swedish counties
