61. Inter-individual variability in spring phenology of temperate deciduous trees depends on species, tree size and previous year autumn phenologyLorène Julia Marchand, Inge Dox, Jožica Gričar, Peter Prislan, Sebastien Leys, Jan Van den Bulcke, Patrick Fonti, Holger Lange, Erik Matthysen, Josep Peñuelas, Paolo Zuccarini, Matteo Campioli, 2020, izvirni znanstveni članek Povzetek: We explored the inter-individual variability in bud-burst and its potential drivers, in homogeneous mature stands of temperate deciduous trees. Phenological observations of leaves and wood formation were performed weekly from summer 2017 to summer 2018 for pedunculate oak, European beech and silver birch in Belgium. The variability of bud-burst was correlated to previous' year autumn phenology (i.e. the onset of leaf senescence and the cessation of wood formation) and tree size but with important differences among species. In fact, variability of bud-burst was primarily related to onset of leaf senescence, cessation of wood formation and tree height for oak, beech and birch, respectively. The inter-individual variability of onset of leaf senescence was not related to the tree characteristics considered and was much larger than the inter-individual variability in bud-burst. Multispecies multivariate models could explain up to 66% of the bud-burst variability. These findings represent an important advance in our fundamental understanding and modelling of phenology and tree functioning of deciduous tree species.
Ključne besede: leaf unfolding, wood formation, coloration, Pedunculate oak, European beech, Silver birch
Objavljeno v DiRROS: 10.06.2020; Ogledov: 1984; Prenosov: 1168
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62. Post-fire effects on development of leaves and secondary vascular tissues in Quercus pubescensJožica Gričar, Polona Hafner, Martina Lavrič, Mitja Ferlan, Nives Ogrinc, Bor Krajnc, Klemen Eler, Dominik Vodnik, 2020, izvirni znanstveni članek Povzetek: 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.
Ključne besede: pubescent oak, cambium, radial growth, xylem, phloem, anatomy, sub-Mediterranean
Objavljeno v DiRROS: 19.03.2020; Ogledov: 2612; Prenosov: 1384
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63. Different belowground responses to elevated ozone and soil water deficit in three European oak species (Quercus ilex, Q. pubescens and Q. robur)Tanja Mrak, Ines Štraus, Tine Grebenc, Jožica Gričar, Yasutomo Hoshika, Giulia Carriero, Elena Paoletti, Hojka Kraigher, 2019, izvirni znanstveni članek Povzetek: Effects on roots due to ozone and/or soil water deficit often occur through diminished belowground allocation of carbon. Responses of root biomass, morphology, anatomy and ectomycorrhizal communities were investigated in seedlings of three oak species: Quercus ilex L., Q. pubescens Willd. and Q. robur L., exposed to combined effects of elevated ozone (ambient air and 1.4 x ambient air) and water deficit (100% and 10% irrigation relative to field capacity) for one growing season at a free-air ozone exposure facility. Effects on root biomass were observed as general reduction in coarse root biomass by -26.8 % and in fine root biomass by -13.1 % due to water deficit. Effect on coarse root biomass was the most prominent in Q. robur (-36.3 %). Root morphological changes manifested as changes in proportions of fine root (<2 mm) diameter classes due to ozone and water deficit in Q. pubescens and due to water deficit in Q. robur. In addition, reduced fine root diameter (-8.49 %) in Q. robur was observed under water deficit. Changes in root anatomy were observed as increased vessel density (+18.5 %) due to ozone in all three species, as reduced vessel tangential diameter (-46.7 %) in Q. ilex due to interaction of ozone and water, and as generally increased bark to secondary xylem ratio (+47.0 %) due to interaction of ozone and water. Water deficit influenced occurrence of distinct growth ring boundaries in roots of Q. ilex and Q. robur. It shifted the ectomycorrhizal community towards dominance of stress-resistant species, with reduced relative abundance of Tomentella sp. 2 and increased relative abundances of Sphaerosporella brunnea and Thelephora sp. Our results provide evidence that expression of stress effects varies between root traits; therefore the combined analysis of root traits is necessary to obtain a complete picture of belowground responses.
Ključne besede: ozone, drought, fine roots, ectomycorrhiza, anatomy, morphology, plants
Objavljeno v DiRROS: 20.02.2020; Ogledov: 2188; Prenosov: 1424
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64. Seasonal radial growth of Black pine (Pinus nigra Arnold) from Bosnia and Herzegovina, monitored by the pinning method and manual band dendrometersSimon Poljanšek, Jernej Jevšenak, Jožica Gričar, Tom Levanič, 2019, izvirni znanstveni članek Povzetek: Despite numerous dendroclimatological investigations into different tree species from Bosnia and Herzegovina, information is lacking on intra-annual wood formation patterns, which would help us to interpret the climate signal in tree rings better. Using the pinning method and manual band dendrometers, we investigated the seasonal dynamics of radial growth of black pine (Pinus nigra Arnold) trees in two successive growing seasons: 2011 and 2012. The up to 60-year-old trees grew in a stand at the base of a hill in the western, mountainous part of the Balkan Peninsula. The seasonal dynamics of wood formation and final number of cells differed between the studied years. Wood formation started in both years in early to mid-March. Differences were noticed in the wood production culmination; in 2011 it occurred at the end of May and beginning of June in 2012 and 2011, respectively. Xylem growth finished in 2012 in the middle of August and in 2011 in the middle of September. Based on the first derivative of the Gompertz function calculated rate of xylem growth was lowest in 2011. The dendrometers recorded a slow increment rate in spring, higher in summer and a decreasing rate again in the late summer in both growing seasons. In comparison with pinning, dendrometers showed a delay in the start of radial growth of up to 20 days in 2012. Additionally, dendrometers showed an increase in stem girth after the end of both growing seasons, when wood formation was already completed. Deviations between the two methods could be ascribed to the influence of water storage dynamics in the main stem and numerous structural processes in bark tissue, which are captured in dendrometer data. The influence of weather conditions on xylem phenology is also indicated by differences between the two studied years, although it is difficult to identify the influence of particular short-term weather events.
Ključne besede: pinning, manual dendrometers, radial growth, Pinus nigra, cambium, Balkan Peninsula
Objavljeno v DiRROS: 11.09.2019; Ogledov: 4963; Prenosov: 3932
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68. Uporaba nadzorovanih poskusov za raziskave debelinske rasti drevesJožica Gričar, 2009, izvirni znanstveni članek Ključne besede: kambij, ogrevanje, ogrevanje, hlajenje, kambijeva aktivnost, celična diferenciacija, ksilogeneza, floemogeneza
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4570; Prenosov: 1952
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69. Dinamika ksilogeneze pri gradnu v letu 2007Jožica Gričar, 2008, izvirni znanstveni članek Povzetek: S svetlobnim mikroskopom smo raziskali sezonsko dinamiko nastanka lesa pri gradnu (Quercus sessiliflora Salisb.) v rastni sezoni 2007. Konec marca so se delitve v kambiju že začele in število celic je naraslo na 10-11 slojev. Maksimalno celično produkcijo smo na ksilemski strani zabeležili v drugi polovici maja, ko smo ugotovili prek 100 ?m prirastka na teden. Kambijeva aktivnost se je zaključila do sredine avgusta in število celic je upadlo na 5-7 slojev. Oblikovanje sekundarne stene in lignifikacija v terminalnih celicah kasnega lesa pa sta potekala še nadaljnjih 4-5 tednov. Dinamika nastanka lesa pri gradnu se razlikuje od debelinske rasti iglavcev.
Ključne besede: Quercus sessiliflora, ksilogeneza, kambijeva aktivnost, traheja, rani les, kasni les
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4641; Prenosov: 1988
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70. Razmerje med ksilemskim in floemskim prirastkom pri jelki (Abies alba Mill.)Luka Krže, Jožica Gričar, Katarina Čufar, 2007, izvirni znanstveni članek Povzetek: Pri 10 zdravih jelkah (Abies alba) smo raziskali anatomsko zgradbo floemskih branik (FB) glede na njihovo širino, razmerje med številom slojev celic v FB in v ksilemskih branikah (KB) iste sezone, razlike v številu slojev celic v FBin KB po obodu posameznega drevesa ter zvezo med širino FB in KB, nastalih vistem letu, ter širino dormantne kambijeve cone (KC). Intaktne vzorce tkiv zaraziskave smo vzeli iz živih dreves v letih 2001 in 2002 ter pripravili preparate prečnih prerezov za svetlobno mikroskopijo. Ugotovili smo zvezo med širino in anatomsko zgradbo FB. Pri ožjih FB je prevladoval rani floem, pri širših pa kasni. Pri širših FB se je v kasnem floemu lahko pojavil dodatni pasaksialnega parenhima. KB so bile 2- do 21-krat širše od FB. Širina KB je poobodu posameznega drevesa bolj variirala kot širina FB. Širina dormantne KC je bila v pozitivni zvezi s širino FB in KB.
Ključne besede: navadna jelka, Abies alba Mill., prirastek, ksilem, floem, kambijeva cona
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4662; Prenosov: 2033
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