Legacies of historic charcoal production affect the forest flora in a Swedish mining district

Abstract

Iron production was historically associated with major impacts on forests worldwide, as vast amounts of wood were harvested to produce the charcoal needed for heating the furnaces and reducing iron oxides in the ore to iron. This impact has left abundant legacies which potentially may remain in the present‐day vegetation. We investigated how remains of historic charcoal production, mainly from the 18th to the early 20th century, at still remaining charcoal kiln platforms (CKPs), affect the current species richness, species occurrences and cover of vascular plants in the ground vegetation in a Swedish mining district located in the boreo‐nemoral forest zone. CKPs have a significantly higher species richness than the surrounding forest, and they also affect cover (negatively) for ericaceous species typically dominating the forest ground vegetation. Several forest species are more frequent at CKPs, and these also harbor significantly more uncommon species, of which many are typical for traditionally managed grasslands. These latter species are likely to represent remnants in present‐day forests reflecting former land‐use such as livestock grazing. The soil chemistry at CKPs is strongly deviating from the surrounding forest, and this, together with a lower cover of ericaceous shrubs, are the most likely mechanisms behind the higher species richness. CKPs represent conspicuous and abundant historic anthropogenic habitats in the forest vegetation. As far as we are aware, the flora at CKPs in boreal and boreo‐nemoral forests has not previously been investigated in detail, and they deserve more attention, both from a biological and a cultural–historical perspective.