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Xylem sap flow and radial growth in Quercus pubescens Willd. from abandoned grasslands in Slovenian Karst region
Martina Lavrič, Klemen Eler, Mitja Ferlan, Dominik Vodnik, Jožica Gričar, 2015, published scientific conference contribution abstract

Published in DiRROS: 03.11.2021; Views: 296; Downloads: 101
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Climatic regulation of leaf and cambial phenology in Quercus pubescens : their interlinkage and impact on xylem and phloem conduits
Jožica Gričar, Jernej Jevšenak, Polona Hafner, Peter Prislan, Mitja Ferlan, Martina Lavrič, Dominik Vodnik, Klemen Eler, 2022, original scientific article

Abstract: Increased frequency and severity of stressful events affects the growth patterns and functioning of trees which adjust their phenology to given conditions. Here, we analysed environmental effects (temperature, precipitation, VPD and SWC) on the timing of leaf phenology, seasonal stem radial growth patterns, and xylem and phloem anatomy of Quercus pubescens in the sub-Mediterranean in the period 2014%2019, when various adverse weather events occurred, i.e. spring drought in 2015, summer fire in 2016 and summer drought in 2017. Results showed that the timings of leaf and cambium phenology do not occur simultaneously in Q. pubescens, reflecting different environmental and internal constraints. Although year-to-year variability in the timings of leaf and cambial phenology exists, their chronological sequence is fairly fixed. Different effects of weather conditions on different stages of leaf development in spring were observed. Common climatic drivers (i.e., negative effect of hot and dry summers and a positive effect of increasing moisture availability in winter and summer) were found to affect the widths of xylem and phloem increments with more pronounced effect on late formed parts. A legacy effect of the timing of leaf and cambial phenology of the previous growing season on the timing of phenology of the following spring was confirmed. Rarely available phloem data permitted a comprehensive insight into the interlinkage of the timing of cambium and leaf phenology and adjustment strategies of vascular tissues in Mediterranean pubescent oak to various environmental constraints, including frequent extreme events (drought, fire). Our results suggest that predicted changes in autumn/winter and spring climatic conditions for this area could affect the timings of leaf and stem cambial phenology of Q. pubescens in the coming years, which would affect stem xylem and phloem structure and hydraulic properties, and ultimately its performance.
Keywords: pubescent oak, leaf development, radial growth, initial earlywood vessel, sieve tube, anatomy, cambial cell production, extreme weather events
Published in DiRROS: 06.09.2021; Views: 427; Downloads: 84
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Post-fire effects on development of leaves and secondary vascular tissues in Quercus pubescens
Jožica Gričar, Polona Hafner, Martina Lavrič, Mitja Ferlan, Nives Ogrinc, Bor Krajnc, Klemen Eler, Dominik Vodnik, 2020, original scientific article

Abstract: An increased frequency of fire events on the Slovenian Karst is in line with future climate-change scenarios for drought-prone environments worldwide. It is therefore of the utmost importance to better understand tree-fire-climate interactions for predicting the impact of changing environment on tree functioning. To this purpose, we studied the post-fire effects on leaf development, leaf carbon isotope composition (%13C), radial growth patterns and the xylem and phloem anatomy in undamaged (H-trees) and fire-damaged trees (F-trees) of Q. pubescens with good re-sprouting ability in spring 2017, the growing season after a rangeland fire in August 2016. We found that the fully developed canopy of F-trees reached only half of the LAI values measured in H-trees. Throughout the season, F-trees were characterised by higher water potential and stomatal conductivity and achieved higher photosynthetic rates compared to unburnt H-trees. The foliage of F-trees had more negative %13C values than those of H-trees. This reflects that F-trees less frequently meet stomatal limitations due to reduced transpirational area and more favourable leaf-to-root ratio. In addition, the growth of leaves in F-trees relied more on the recent photosynthates than on reserves due to the fire disturbed starch accumulation in the previous season. Cambial production stopped 3 weeks later in F-trees, resulting in 60% and 22% wider xylem and phloem increments, respectively. A novel approach by including phloem anatomy in the analyses revealed that fire caused changes in conduit dimensions in the early phloem but not in the earlywood. However, premature formation of the tyloses in the earlywood vessels of the youngest two xylem increments in F-trees implies that xylem hydraulic integrity was also affected by heat. Analyses of secondary tissues showed that although xylem and phloem tissues are interlinked changes in their transport systems due to heat damage are not necessarily coordinated.
Keywords: pubescent oak, cambium, radial growth, xylem, phloem, anatomy, sub-Mediterranean
Published in DiRROS: 19.03.2020; Views: 1644; Downloads: 859
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Vpliv vremenskih razmer na lesno-anatomske značilnosti pri puhastem hrastu s Podgorskega Krasa
Martina Lavrič, Jožica Gričar, 2016, original scientific article

Abstract: V okviru raziskave smo se osredotočili na vpliv vremenskih dejavnikov na lesno-anatomske značilnosti puhastega hrasta (Quercus pubescens Willd.), ki je ena od dominantnih domorodnih drevesnih vrst v slovenskem Submediteranu. V obdobju 2009%2014 smo raziskali povezave med različnimi lesno-anatomskimi parametri (končna širina branike, širina kasnega in ranega lesa ter premer, površina in število trahej ranega lesa) in vremenskimi dejavniki (padavine, temperatura in vsebnost vode v tleh). Zanimal nas je tudi potencial izbranih lesno-anatomskih parametrov ter komplementarnost oziroma enakovrednost le-teh za proučevanje podnebja na Podgorskem krasu. Preliminarni rezultati so pokazali, da so bili anatomski parametri povezani predvsem s temperaturo. Širina ranega lesa in površina trahej ranega lesa sta bili pozitivno povezani z maksimalno temperaturo, število trahej v ranem lesu in širina lesne branike pa pozitivno povezana s povprečno temperaturo v obdobju pred in na začetku kambijeve aktivnosti (januar%maj). To nakazuje, da vremenske razmere v navedenem obdobju pomembno vplivajo na hidravlične lastnosti ksilema. Pri širini kasnega lesa smo ugotovili največ povezav s temperaturo v poletnih mesecih, pri trahejah ranega lesa pa s temperaturo v obdobju januar%april. Vpliva padavin na razvoj ksilemske branike z našimi rezultati nismo potrdili. Ugotovili smo, da so širina kasnega lesa in značilnosti trahej ranega lesa primerni lesno-anatomski parametri, ki vsebujejo komplementarne informacije o vplivu vremenskih razmer na debelinsko rast puhastega hrasta. Poudariti je treba, da so bile naše analize opravljene v razmeroma kratkem časovnem obdobju in da bi bile za natančnejše rastno-podnebne zveze potrebne dodatne dolgoletne študije.
Keywords: Quercus pubescens, kras, vreme, anatomija lesa, lesna branika, kasni les, rani les, traheja
Published in DiRROS: 06.03.2017; Views: 4737; Downloads: 641
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