Table 2 The eligibility criteria for article screening

Populations

Included:

Boreal forests in Fennoscandia and European Russia (the dominating tree species in the study area must be spruce or pine)

Exposure

Included:

Even-aged forest management

Uneven-aged forest management

Excluded:

Thinning (studies where the objective is to study precisely the effects of thinning, thinned even-aged forests were included)

Retention (articles where the objective is to study precisely the effects of retention)^a

Management where the stems and all cutting biomass were left in the forest (restoration, not for production purposes)

Comparators

Included:

Young even-aged forest, age ≤ 80 years

Mature even-aged forest, age ≥ 80 years

Natural or near-natural forests, including protected forest areas, national parks

Retention felling (only included in the case of experimental studies where traditional clearcut (i.e. all the trees are removed) is one of the treatments; otherwise even-aged forests where retention felling had been done were included as even-aged forest)

Excluded:

Non-forest lands, e.g. agricultural areas, parks in urban areas

Tree plantations not considered to be forest, e.g. Christmas tree plantations

Forested peatlands

Outcomes

Included:

Species richness

Abundance (counts or coverage)

excluded:

All data on non-terrestrial species and bacteria

Data on tree species

Amount of dead wood (is treated as an effect modifier)

Community composition indices

Species biomasses

Visiting frequency/habitat occupancy/breeding success etc.

Number of nests/grouse leks/ant mounds etc.

Study design

Included:

Control-intervention field studies

Excluded:

Simulation/modelling studies (even partly simulated/modelled)

Studies where exposure/comparator and outcome data are from different sources (combining the data of two different field data)

Habitat selection studies

Edge effect studies (But included if there are separate areas, for example, clearcut interior/edge area/forest interior. In addition, interior areas should be located far enough from the edge relative to the species in question so that edge effects do not compromise the results)

Studies, where the study subject (often lichen) is transplanted to the exposure/comparator area

Language

Included:

English

Finnish

Swedish

Russian