FOREST HEALTH IN A CHANGING CLIMATE: COMPARATIVE ASSESSMENT OF DEFOLIATION TRENDS IN ROMANIAN AND SERBIAN FORESTS

Abstract

This study examines forest health dynamic in Romania and Republic of Serbia between 2020 and 2024, focusing on crown condition and defoliation trends within the ICP Forests monitoring framework (Level I). Annual defoliation data by species and defoliation class were compared with climatic variability using the De Martonne Aridity index. Results indicate moderate interannual fluctuations in defoliation, with Romania exhibiting mean defoliation levels of 15-16% and Serbia maintaining over 80% of trees non-defoliated classes. Broadleaved species such as Populus spp. and Quercus spp., showed the highest defoliation rates (up to 40%), while Fagus sylvatica (L.), Abies alba (Mill.) and Picea abies (L.) Karst. demonstrated greater resilience. A negative correlation was identified between aridity index values and defoliation intensity, with drier years (2022, 2024) associated with increased crown damage. Biotic stressors, particularly insects and fungi, amplified defoliation under dry conditions. The findings highlight the influence of climatic aridity on forest vitality and underscore the importance of integrated monitoring to support adaptive forest management in the Carpathian-Balkan region.