Table 1 Types and levels of retention with examples of types of key biotopes and key elements retained in the harvesting areas in NW Russian forests

Uncut patches; 0.001–30 ha

Mainly deciduous and low-diameter or decaying coniferous trees on paludified or unreachable sites with a high amount of CWD.

“No economic value”

Since the 1910s

Seed trees; 20–25 trees per ha in groups of 3–5 trees

Mainly pine and spruce, left to ensure natural regeneration

Since the 1930s

Understory, low-diameter trees; all possible viable seedlings

Left to ensure natural regeneration and reach the target stocking level

Since the 1930s

Coarse woody debris

Snags and logs of different sizes, tree species, and decay classes.

“No economic value”

Since the 1930s

Key biotopes; the whole forest patch is completely preserved; ca. 0.1–100 ha

Paludified patches; ecotones between peatlands and forests; forest “islands” in peatlands; forest patches on rocky sites or steep slopes, cliffs, and canyons; spruce-black alder and paludified spruce forests, pine forests of herb-sphagnum type; patches with uneven-aged structure and old trees; habitats of red-listed species of different taxonomic groups; places of capercaillie mating call

Since 1978, with more types added afterwards

Buffer zones around key biotopes or elements, 20–50 m; buffer zones around trees with big nests, 300–500 m

Buffer zones around ecotones between peatlands and forests; forest buffers around small water bodies; forests on steep slopes and cliffs and canyons; zones around badger and fox burrows; zones around trees with bird nests; forests around boulders of more than 6 m

Since 2000

Key elements; completely preserved

Trees of regionally rare species; red-listed tree species; old and decaying trees; snags; high stumps from naturally broken trees; trees with nests and hollows; uprooted trees; logs of different decay classes

Since 2000