Health Conditions of ‘Veteran Trees’ and Climate Change

This study explores the health status of veteran Zelkova serrata trees (average age 300 years) in the Pohang region in the context of long-term climatic trends and local environmental variability. Eleven nationally designated veteran trees were monitored using physiological indicators Soil Plant Analysis Development (SPAD) values and live crown ratio (LCR), internal structural assessment (sonic tomography-derived decay ratio), and environmental parameters including meteorological records and Landsat-derived Land Surface Temperature (LST) data from 2000 to 2025. While recent years showed localized heat-extreme events, most sites displayed spatially heterogeneous yet gradually increasing LST trends, with 2024 recording the highest values at more than half the locations. Tree vitality differences were more strongly associated with site specific microclimatic conditions than with uniform long-term climate shifts: trees in cooler or less urbanized zones showed higher SPAD values and lower decay levels, whereas those in warmer, edge-influenced sites exhibited signs of physiological stress. The results indicate that rising summer surface temperature—and their interaction with atmospheric drying—intensify water-stress impacts, but the actual tree responses are modulated by local land-cover and soil stability contexts. These findings underscore the need for integrated, multi-scale assessment of veteran tree health and suggest that conservation practices should incorporate microclimate-based intervention strategies.