Health evaluation and protection management of ancient trees in historic city

This study analyzes the distribution and health status of unprotected ancient trees in Gyeongju, South Korea. Based on a comprehensive literature review and field database, evaluation indicators were established for growth parameters (tree height, diameter at breast height(DBH), crown width, soil pH, soil compaction, and estimated chronological age) and health indicators (crown architecture, crown structure, crown vigor, and incidence of pests and diseases). The Analytic Hierarchy Process (AHP) ranked the relative importance of health indicators as: presence of pests and diseases > crown architecture > bark condition > crown condition. A total of 166 unprotected ancient trees were surveyed. A four-tier health grading system was developed using cluster analysis, Shapiro-Wilk normality test, Kruskal-Wallis nonparametric test, and one-way ANOVA. The system comprises Preservation grade (optimal health), Protection grade (preventive care required), Management grade (active intervention), and Treatment grade (severe decline), with species-specific management protocols for each grade. Ten high-risk trees were identified as candidates for statutory protection. Critical gaps in current conservation frameworks were identified, including legal insufficiencies for trees exceeding age thresholds (over 100 years) and the lack of validated, low-cost alternatives to specialized dendrological tools such as DBH tapes. To address these gaps, systematic monitoring, resource-efficient assessment methods, and species-specific age prediction indicators are recommended. This study presents the first integrated health evaluation system for unprotected ancient trees in East Asian cultural landscapes, providing a practical framework for field managers and policymakers to implement cost-effective monitoring, targeted interventions, and sustainable conservation strategies, supporting ecological resilience and cultural heritage preservation.