Table 2 Woodland key habitats recorded in the NFI since 2003, following the Complementary Hot-spot Inventory (CHI) methodology, with the main criteria for defining and mapping whole or parts of the 0.2 ha plot as a habitat polygon. The rightmost column gives the occurrence of the respective CHI habitats as of 2016 (inventory period 2014–2018)

Standing deadwood

• ≥ 40 standing dead trees·ha⁻¹ with dbh ≥10 cm

• Distance to other dead trees ≤15 m

Downed deadwood

• ≥ 40 downed dead trees·ha⁻¹ with diameter at root end ≥10 cm

• Distance to other downed dead trees ≤15 m

Trees with nutrient-rich bark

• Occurrence of maple (Acer platanoídes L.) or any tree species with bark lichens of the lobarion group

• ≥ 20 trees·ha⁻¹ of any of the above categories (60 in West and North Norway)

• Distance to other trees with nutrient-rich bark ≤25 (15) m

Trees with pendant lichens

• ≥ 100 trees·ha⁻¹ with at least 10 individuals/groups of pendant lichens of more than 10 cm length within 1 m² of the vertical tree crown area

• Occurrence of trees with lichens of the species Evernia divaricata (L.) Ach. or Usnea longissima Ach.

• Only assessed for the lower 5 m of the tree

Deciduous boreal trees in late successional stage

• ≥ 40 trees·ha⁻¹ with dbh ≥20 cm of any of the species Populus tremula L., Sorbus aucuparia L., Alnus incana L., Salix caprea L., Prunus padus L., or Betula spp.

• Northern Norway: only P. tremula is considered

Old trees

• ≥ 30 standing old trees·ha⁻¹

• Minimum age for spruce/pine = 150/200 yrs.

• Deciduous trees are included dependent on dbh and species (minimum dbh is 30–40 cm for boreal species and 40–50 cm for noble hardwoods)

• Distance to other old trees ≤20 m

Luxuriant ground vegetation

• Nutrient-rich forms of selected vegetation types sensu (Larsson 2005)