Anatomical and ecophysiological responses of Quercus pubescens Willd. to different soil water availability from the submediterranean phytogeographic region of SloveniaLavrič, Martina (Avtor) Gričar, Jožica (Mentor) Vodnik, Dominik (Komentor) pubescent oaksubmediterranean climatekarstdroughtradial growthsap flowleaf developmentnon-structural carbohydratesstembranchxylemphloemcambiumearlywoodvesselstomatal conductanceIntra-annual variations in leaf development, radial growth (including the secondary phloem part), sap flow and non-structural carbohydrates (NSCs) have been rarely studied in deciduous trees from drought-prone environments. In order to better understand the chronological order and temporal course of these processes, we monitored leaf phenology, xylem and phloem formation (in different tree parts), sap flow (HRM method), variations in NSC amounts and relationship between various wood-anatomical parameters and climatic factors in Quercus pubescens Willd. from Podgorski Kras in Slovenia during study period 2014–2016. For this purpose two research areas (RA) were selected, where at RA2 two adjacent plots differing in bedrock and soil type (flysch with eutric cambisol, high water retention - F; limestone with rendzic leptosol, low water retention - L) were sampled. We found that initial earlywood vessels were fully lignified and ready for water transport before bud opening at the beginning of April. Buds started to open in the second half of April and full leaf unfolding occurred by the end of May. Sap flow was increasing contemporarily with leaf development and LAI values. In the initial three weeks of radial growth, phloem growth preceded that of xylem. Cambial cell production was one month longer at the stem base than in branches. In addition, the xylem ring was wider than the phloem ring in all three parts. The amount of NSCs significantly differed among the tissue parts and sampling dates but not between the plots. Starch amounts were the highest in xylem and the amounts of free sugars were highest in inner phloem + cambium. Trees on F were more buffered against drier hydroclimatic conditions due to a higher availability of soil water. In the period of severe drought, sap flow density in trees growing on L was decoupled from the changes of vapour pressure deficit, due to increased employment of water conservation strategies (decreases in stomatal conductance). This was further translated into stomatal limitation of photosynthesis and contributed to reduced radial stem growth that revealed smaller yearly xylem increments in L trees and anatomical acclimations of conductive tissues, supporting/preserving trees' hydraulic function. Xylem ring width, early- and latewood widths, diameter, area and number of earlywood vessels were mainly related to temperature. Our study confirmed that the temporal sequence of leaf development and radial growth are not contemporary. Soil water availability substantially influenced secondary growth in the stem, whereas NSC amounts seemed to be less affected. It has been demonstrated that latewood width and earlywood vessel characteristics are promising wood-anatomical parameters containing complementary information on the impact of weather conditions on radial growth. We concluded that climate is not the only driver for radial growth of Q. pubescens at the selected locations; soil type with respect to water retention potential is also important environmental feature that needs to be considered in wood formation studies and growth models in the future.[M. Lavrič]20192019-10-25 07:45:03Doktorsko delo/naloga112569sl