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

Iron production was historically associated with one of the major impacts
on forests worldwide, as vast amounts of wood were harvested to produce
the charcoal needed for 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 field layer vascular plants 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 field-layer. 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.