Biodiversity composition reflects the history of ancient semi-natural woodland and forest habitats—Compilation of an indicator complex for restoration practice

For centuries, Fennoscandian wooded meadows and woodland pastures (Habitats Directive habitat types *6530 and 9070 respectively) covered large areas of Northern Europe. In the Twentieth Century, abandonment-driven encroachment has led to the wooded grasslands changing into what may be considered as old-growth deciduous forests. The present paper examined whether the present stand structure and the composition of three contrasting functional groups (herbaceous layer vascular plants, epiphytic bryophytes, and earthworms) could serve as indicators of the historic origin of the forest patches, i.e. to what extent changes in ecological conditions in overgrown woodlands have shifted towards broad-leaved forests with ancient trees. Indicators were tested for the objective of restoration planning of habitat quality, i.e. whether semi-open woodlands could be restored or if it would be more appropriate to preserve them as broad-leaved forests. The study was carried out by comparing the composition of ancient forest cores, forest edges and overgrown wooded grasslands. The land use history of sample sites was examined from historical topographical maps and aerial photos. sults showed that as long as 60 years after abandonment, parts of the studied forests still retained some light-demanding plant species characteristic of historical wooded grasslands. The composition of earthworm communities was similar in all of the studied historical forest groups. Only some of the stand structure characteristics and epiphytic mosses indicated that there were differences between ancient forest cores and overgrown wooded grasslands. We conclude that the combination of various functional indicators should be used in the evaluation of successional woodlands for habitat restoration.