Ancient woodland indicator species: can old herbarium specimens supplement recent records to inform ecological management?

Old herbarium specimens have become increasingly well-recognised as a rich source of ecological baseline data. For long-continuity plant communities, such as ancient woodland, these records may be particularly important for present day ecological management. To evaluate this potential, searches for pre-1950 Ancient Woodland Indicator (AWI) herbarium specimens collected in East Gloucestershire, UK, were conducted using digital open access sources and the physical Royal Agricultural University herbarium. In total 305 specimens were retrieved from twelve herbaria, with small regional collections being particularly important sources. The earliest specimen dated to 1834. There was a significant association between old specimen availability and year of collection, due to a peak in the late-1800s and early-1900s. Over half of the AWI species for the region were represented, although some taxonomic bias was evident. To determine if old AWI specimens contributed any new location records, 246 unique specimens with detailed georeferences were mapped and compared to the locations of 1950-1999 and 2000-2021 biological records. One third of the pre-1950 specimens had not been recorded in the same locality since collection of the old specimen, indicating either a gap in recent records or floristic change. However, length of time since specimen collection was not a predictor of a 1950-2000 or 2000-2021 record in the same locality. Overall, it is highly recommended that policy-makers, land managers, and field surveyors consult old AWI herbarium records for ancient woodland identification, management, and restoration.