The dissertation is devoted to investigating the current condition, silvicultural and forest inventory characteristics, growth patterns, radial growth dynamics, and spatial structure of silver fir (Abies alba Mill.) stands on the northeastern macroslope of the Ukrainian Carpathians. Particular attention is paid to assessing the resilience of silver fir stands under climate change, predicting their productivity, and improving technologies for producing high-quality planting stock for forest regeneration.
The research aimed to assess the condition, growth, productivity, and radial growth dynamics of silver fir, to identify the patterns governing the formation of resilient uneven-aged forest stands, to predict their development under changing climatic conditions, and to improve the technology for producing high-quality planting stock.
The study employed a comprehensive set of silvicultural, forest inventory, dendrochronological, statistical, and mathematical methods. Dendrochronological analyses were conducted in accordance with internationally accepted methodologies using the specialised software packages TSAP-Win and DplR, while statistical analyses were performed using modern data-processing software.
The total area of forest stands containing silver fir on the northeastern macroslope of the Ukrainian Carpathians was estimated at approximately 130.5 thousand hectares, representing 8.2% of the total forest area of the study region. The largest proportion of silver fir forests is concentrated in Lviv Region. Silver fir exhibited high phytocoenotic plasticity, occurring in 71 forest site types grouped into seven forest typological groups. An imbalance in the age structure of silver fir forests was identified, together with the underutilization of the productive potential of forest site conditions.
The patterns of radial growth formation of silver fir were investigated in different natural regions of the Ukrainian Carpathians. A statistically significant declining trend in radial growth during recent decades was identified, indicating deteriorating growth conditions and a reduction in the adaptive capacity of mature and overmature stands under current climate change. Characteristic pointer years associated with meteorological anomalies were identified, and radial growth dynamics were projected based on the cyclicity of natural processes. A distinctive feature of silver fir radial growth is its ability to persist in the regeneration layer for many years while maintaining vitality and responding rapidly to improved environmental conditions when growth opportunities become available.
The spatial structure of silver fir stands was investigated, and its influence on natural regeneration processes was assessed. The most favourable conditions for natural regeneration were found in uneven-aged, multi-layered stands located on northern and northeastern slopes, whereas regeneration intensity decreased considerably on southern exposures. A relationship was established between forest ecosystem functioning and the spatial distribution of tree species, which influences regeneration dynamics and stand resilience to abiotic factors.
Scientific novelty. The research provides a comprehensive assessment of the current condition, productivity, spatial structure, and radial growth dynamics of silver fir stands on the northeastern macroslope of the Ukrainian Carpathians. Long-term tree-ring chronologies were developed, the response of silver fir to climate change was quantified, and the relationships between natural regeneration, stand spatial structure, and orographic conditions were identified.
Practical significance. The study improves the technology for producing high-quality silver fir planting stock with both bare-root and containerized root systems. Practical recommendations have also been developed for establishing resilient uneven-aged silver fir stands and for implementing adaptive and close-to-nature forest management practices.
