The map and attributive databases of the Paanajarvi National Park (NP) forest survey were analysed. The aspects analysed include the patterns of forest land distribution by land categories and the distribution of forested areas by the main tree species, forest types and site quality classes. Special attention was paid to the NP’s forest tract age structure, specifically the types of the age structure of coniferous stands. It is shown that pine stands in the NP had been exploited intensively up to the 1940s, whereas its spruce forests have remained in a near natural state. The study revealed that, despite the fundamental transformation from a relatively even-aged to an all-aged structure, the standing stock did not drop dramatically in any of the ‘major’ stages of the succession cycle. This pattern is evidence that in the absence of catastrophic events primeval boreal forests can remain sustainable for many centuries.