Establishing consensus criteria for determining heritage tree status

ABSTRACT Heritage trees are identified and valued based on important historical, cultural and physical criteria that these specimens possess. This research attempts to support heritage tree programmes by identifying a standardised set of expert-verified criteria that can be applied regardless of geographic location. An initial set of 40 criteria were derived from an analysis of 46 case studies and presented to a panel of heritage tree experts to obtain consensus on the core criteria that should be used by any heritage tree programme. A three iteration Delphi method was used to evaluate the criteria and allowed additional content to be generated by the panel. The result saw 50 criteria analysed to produce a set of 16 consensus core criteria and an additional 29 situational criteria that can apply on a case-by-case basis. This study identified the existence of 16 common values shared among these tree programmes and serves as an initial template for use by current and proposed heritage tree programmes to select ideal candidates. Through this standardised evaluation system, the current patchwork of heritage tree programmes now has the potential to become a unified network leading to the increased awareness and protection of these trees.