The pedunculate oak (Quercus robur L.) is a major tree species in Europe, but it has faced recent growth decline and dieback events in some areas resulting in economic and ecosystem losses. In the southeastern edge of its natural distribution in eastern Romania, rising temperatures since the 1980s, when a shift towards warmer and more arid conditions occurred, increased evaporative demand and triggered growth decline. We analyzed the adaptive potential of six oak stands (333 individual trees) with ages ranging between 97 and 233 years, located in three wet and three dry sites. Results showed unstable climate-growth correlations with a breakpoint after 1985 when climate warming intensified. Wet soil conditions from early spring to summer enhanced growth; on the contrary, a high evaporative demand linked to warmer conditions and greater potential evapotranspiration reduced growth, particularly in wet sites. After 1985, drought stress induced a reduction in latewood width in dry sites. The relationship between growth and summer-autumn drought intensified during the last decades in all sites. Warmer spring conditions negatively affected oak growth, particularly latewood production. Wet sites had lower resilience indices, and we also noted a post-1985 progressive reduction of growth resilience. Slow-growing trees from dry sites showed growth decline, which could be an early-warning signal of impending dieback and tree death. In contrast, fast-growing trees from wet sites showed sustained relative growth improvement, which was attributed to tree age and size effects. After 1985, the pedunculate oak is more vulnerable to drought damage in dry sites near the southeastern distribution limit in response to hotter winter-spring droughts.
Soil creep is a slow gravitational process. It differs from other catastrophic slope processes such as landslides, snow avalanches, and rockfalls in its dynamics and character. However, it can significantly affect tree growth. Creep movements can be analyzed based on the tree rings. This study analyzed the dynamics and spatiotemporal activity of creep in the Balea glacial valley (Southern Carpathians) under the Transfagarasan highway on an anthropogenic slope, using tree rings to define the spatiotemporal activity of creep and assess its potential driving and triggering factors. The dendrogeomorphological analysis included 54 Norway spruces (Picea abies (L.) Karst). A total of 118 tree-ring series were obtained, and a 35-year chronology was constructed based on the eccentric growth of tree rings and reaction wood, with a mean recurrence interval of 17.4 years. The spatial pattern of the disturbed trees in the event years was tested using Moran's I index. The presence of creep in this area is indicated by the stems of young trees taking on a 'd' shape or a 'pistol-butted' form, as well as the predominant inclination of the stems downslope direction. This inclination is not chaotic, as is typical of forests affected by landslides. The manifestation of creep is influenced by pre-existing factors, such as the substrate consisting of crystalline shale and the blanket of rubble arranged in the direction of the slope, as well as causal factors, such as the slope and precipitation. Precipitation falling within 24 h during June or July and intervals with frosty cycles from November to December and January to March were also contributing factors.