Intra-annual leaf phenology, radial growth and seasonal variation in NSC in the xylem and bark tissues of Quercus pubescens were analysed. For this purpose, samples of outer xylem and phloem (separately for non-collapsed and collapsed living phloem) tissues of Q. pubescens trees from the Slovenian sub-Mediterranean region were collected from September 2015 until September 2016. Moreover, Q. pubescens trees growing at two nearby sites differing in the soil structure (flysch and limestone) were sampled to check the impact of soil structure on radial growth capacity of the selected trees. Results showed that some of the patterns of radial growth coincided in oaks from the two plots (i.e. onset of cambial cell production, peak of xylem / phloem growth, transition from early to late xylem/ phloem and cessation of wood formation), whereas others differed (i.e. cessation of cambial cell production, rate of xylem / phloem production and width of xylem / phloem increments). The amounts of NSC significantly differed among the tree tissue parts (i.e. xylem, inner phloem and outer phloem) and sampling dates but not between the two sites. Among the analysed free sugars, significant seasonal variations in the amounts were detected for raffinose, fructose and glucose. Highest starch concentrations found in outer xylem are in contrast to the previous observations in conifers, where highest starch amounts were found in inner bark; however, it could be explained by the differences in basic anatomy of wood and bark tissues of conifers and hardwoods.
B.06 Other
COBISS.SI-ID: 5065382Pubescent oak (Quercus pubescens Willd.) typically grows in Mediterranean areas where changing climate will lead to an increase in the frequency and severity of drought events. In our study growth and drought responses of pubescent oak were investigated in trees growing on two different soil types (flysch and limestone) in the Slovenian sub-Mediterranean. In two years, 2015 and 2016, we monitored xylem and phloem formation dynamics, leaf development and xylem sap flow. Despite shorter cambial cell production period in 2016 than in 2015, the xylem and phloem increments were wider due to higher rate of cell production Emergence of first leaves occurred in the second half of April in all cases and coincided with the beginning of the initial earlywood vessel formation. Leaf area index increased with leaf development. Sap ?ow increased contemporarily with leaf development at the beginning of the growing season. In contrast, during the growing seasons, sap flow was driven by climatic factors, especially vapour pressure deficit, air temperature and solar radiation. In the period April-September sap flow well reflected the difference in soil water availability between the research plots in both years. During drought period trees still reflect high water use efficiency what confirms that Q. pubescens is well adapted to survive severe water shortage in the soil. Integrative structural-functional approach presented in this work revealed that climate is not the only driver of radial growth in Q. pubescens at the selected plots. Soil type is also important environmental feature that needs to be considered in such studies.
B.06 Other
COBISS.SI-ID: 5074342In Central Europe, it is expected that a changing climate will increase the frequency and severity of drought events. Among all European regions, the Mediterranean appears to be the most vulnerable to climate change. In Slovenia, pubescent oak (Quercus pubescens Willd.) is one of the dominant native tree species in Karst region and is ecologically important as it is growing in forests that prevent degradation of vulnerable, shallow and erosion-prone soil. Despite its importance, information about its growth patterns in Slovenian Sub-Mediterranean is lacking. In the study, we monitored intra-annual xylem and phloem formation in combination with leaf development and xylem sap flow measurements. For this purpose, in two growing seasons of 2015 and 2016, two research plots that differ in water availability were selected. We found that seasonal dynamics of wood formation can be linked with seasonal patterns of xylem sap flow, that is also well correlated with leaf phenology in early spring. Xylem and phloem growth patterns differ between the two sites; trees with higher water availability had wider annual increments. Preliminary results confirm that soil water availability is closely related to radial growth of pubescent oak.
B.06 Other
COBISS.SI-ID: 4968614Lecture on the growth of plant thickness for doctoral students, postgraduate students and researchers at PLECO, University of Antwerp, Belgium. Intra annual information on the radial growth of trees is crucial for modelling in dendroclimatological and dendroecological studies by helping to understand and explain the climatic signals recorded in ring width and anatomical structure of wood. Radial growth of trees and cambial activity, a brief review of publications about seasonal dynamics of wood formation, which is currently underway in Europe, and the potential of research on the phloem formation was presented at the lecture. I also presented our latest results and publications.
B.05 Guest lecturer at an institute/university
COBISS.SI-ID: 4850086Tree growth is intimately linked to the environment, which directly influence physiological processes. Trees continuously adjust their structure to fit the changing environmental conditions. In the processes of radial growth, which encompasses xylogenesis and phloemogenesis, these structural adjustments can be achieved. Therefore, wood and phloem anatomy can represent a good indicator of tree success and performance. Xylem formation has already proven to be influenced by environmental factors, whereas drivers of phloem formation and structure have generally been less investigated. Unlike wood formation, annual formation of phloem is crucial for tree survival as it maintains the translocation pathways for photosynthates from leaves to the tissues where growth and storage occur. In the presentation, various intra-annual patterns of xylem and phloem development of trees from different environments will be shown. Cambial rhythm and xylem and phloem anatomy of trees from temperate and (sub)Mediterranean will be presented to demonstrate the plasticity of their radial growth, which enables them to respond and adapt to changing environmental conditions. Finally, we will discuss how radial growth studies can complement with ecophysiological and dendroecological observations. Understanding how the secondary growth of trees responds to changing environmental conditions contributes to the major scientific challenges related to future tree performance under global climate change.
B.04 Guest lecture
COBISS.SI-ID: 5199014