A simple approach to forest structure classification using airborne laser scanning that can be adopted across bioregions

•A simple two-tier approach to classify forest structural types (FSTs).•Higher tier classifies single storey/multi-layered/reversed J.•A lower tier classifies young/mature and dense/sparse subtypes.•Airborne laser scanning was employed for a multisite FST classification.•This approach paves the way toward transnational assessments of FSTs.