Plasticity and climatic sensitivity of wood anatomy contribute to performance of eastern Baltic provenances of Scots pine

Abstract

The efficiency of water use and transport are among the main factors affecting competitiveness, growth, and distribution of trees under warming climate. The phenotypical and genetic plasticity of tree populations is considered as an indicator of their adaptive capacity under changing environment. Climatic changes are expected to affect growth of Scots pine (Pinus sylvestris L.), and selection of reproductive material among the populations suitable for future climates has been advised for sustaining productivity of stands. In this regard, provenance trials can serve as source of comprehensive information about growth plasticity and climate-growth interactions of diverse populations. Quantitative wood anatomy can provide detailed information about xylogenesis and factors affecting it, which are crucial for long-term predictions. Wood anatomy of two top- (Gustrow and Rytel), two low-performing (Eibenstock and Dippoldiswalde), and one local (Kalsnava) provenances of Scots pine from the eastern Baltic region growing in three provenance trials in Latvia was studied using mixed models, accounting for the experimental design, as well as using the time-series approach. Provenance had a significant effect on the studied wood anatomical proxies, indicating genetic adaptation of xylogenesis. The top-performing provenances, which originated from warmer and drier conditions, had tracheids with larger lumens and thinner walls, thus indicating adaptation to water deficit. The top-performing Rytel provenance showed the highest phenotypical plasticity of lumen cross-section area and cell wall thickness of stemwood tracheids. The studied low-performing provenances, which originated from the Orr Mountains, had tracheids with thicker wall and smaller lumens, likely to ensure mechanical durability. The local provenance showed intermediate values of the studied wood anatomical proxies. The effect of provenance on wood anatomical proxies showed some variations among the trials, which differed by continentality, likely due to ecological transfer distance. The studied anatomical proxies were affected by weather conditions prior and during formation of a tree ring, yet these relationships differed by trial and provenance. In general, wood anatomy of earlywood was affected by temperature in the dormant period and beginning of summer, as well as precipitation in the end of the previous vegetation period. Proxies of latewood showed correlation with temperature (negative) and precipitation (positive) in summer, suggesting response to the availability of water. Considering the observed relationships, the top-performing provenances, particularly Rytel, have a high potential to sustain productivity of stands within the region in the future.