CONDITION OF PINE TREES AND ANNUAL DIAMETER GROWTH IN A WARMING CLIMATE

Abstract

Understanding the impact of climate change on the condition and growth of different-aged pine forests (mature and middle-aged) at the Aukštaitija complex monitoring station is crucial. This study aimed to identify significant relationships between meteorological factors and their effects on forest responses. Over 30 years of annual growth data for pine trees and key meteorological parameters were used, following the UNECE ICP IM methodology for monitoring conditionally natural ecosystems. Dendrochronological methods revealed both direct and complex effects of meteorological factors on trunk diameter growth changes. The analysis showed a statistically significant increase in precipitation and temperature over the 31-year study period. Middle-aged forests were more sensitive to changes, with average defoliation ranging from 13% to 27%, while mature forests showed a fluctuation of around 15proc. since 2000. Growth increased from 1993 to 2006, followed by a decline from 2006 to 2024 in both age categories. Correlation analysis indicated that higher precipitation in September and elevated temperatures in June adversely affected the crown condition of pines, increasing defoliation and suppressing annual growth. The findings illustrate varying responses to climate change stressors among pine forests of different ages, signifying a serious threat to forest ecosystems.