Open woodland dominated by spruce (Picea abies or P. obovata) on acid peat or around active bogs and poor fens with nutrient-poor ground waters occurring through the boreal zone and locally, where ground conditions permit, in the continental zone.
Remark: Mire forests occurring in ombrotrophic conditions and those occurring in minerotrophic conditions (in fens or at sites influenced by spring water) can be considered as two different habitats characterised by a different floristic composition of the herb layer. This distinction can be seen not only within spruce forests but also within pine forests and larch forests.