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Iskalni niz: "avtor" (Jožica Gričar) .

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Makroskopske in mikroskopske značilnosti lesa
Jožica Gričar, Peter Prislan, 2022, strokovni članek

Ključne besede: anatomija lesa, značilnosti lesa, drevesne vrste
Objavljeno v DiRROS: 13.12.2022; Ogledov: 83; Prenosov: 10
.pdf Celotno besedilo (323,41 KB)

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Tree rings, wood density and climate–growth relationships of four Douglas-fir provenances in sub-Mediterranean Slovenia
Luka Krajnc, Jožica Gričar, Jernej Jevšenak, Polona Hafner, Robert Brus, 2022, izvirni znanstveni članek

Povzetek: Tree rings, wood density and the climate–growth relationship of four Douglas-fir provenances were analysed separately for the juvenile and adult phases. Four provenances were selected from an existing IUFRO provenance trial planted in 1971 based on their diameter at breast height and vitality. Increment cores were extracted from individual trees, on which we measured tree-ring widths (RW), earlywood widths (EWW) and latewood widths (LWW). Wood density was assessed in standing trees using resistance drilling. The climate–growth correlations were calculated between provenance chronologies of RW, EWW, LWW and latewood share, and the day-wise aggregated Standardised Precipitation-Evapotranspiration Index (SPEI). The analysis was done separately for the juvenile and mature phases of growth. Provenances 1064 (Jefferson) and 1080 (Yelm) exhibited larger annual radial increments than provenances 1028 (Merrit) and 1089 (Cathlamet). The two provenances with the highest annual radial increment in the juvenile phase did not exhibit the same trend in the adult phase. In all provenances, RW, and consequently EWW and LWW, were wider in the juvenile than in adult phase. The share of latewood was in all cases higher in juvenile wood than in mature wood. All four provenances had similar wood densities in both analyzed growth phases. Our analysis showed that when selecting the most promising provenance for planting, possible changes in relative growth rate from the juvenile to adult phase need to be considered.
Ključne besede: Pseudotsuga menziesii, SPEI, juvenile phase, adult phase, latewood share, resistance drilling
Objavljeno v DiRROS: 21.11.2022; Ogledov: 87; Prenosov: 20
.pdf Celotno besedilo (3,07 MB)
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Different wood anatomical and growth responses in European beech (Fagus sylvatica L.) at three forest sites in Slovenia
Domen Arnič, Jožica Gričar, Jernej Jevšenak, Gregor Božič, Georg von Arx, Peter Prislan, 2021, izvirni znanstveni članek

Povzetek: European beech (Fagus sylvatica L.) adapts to local growing conditions to enhance its performance. In response to variations in climatic conditions, beech trees adjust leaf phenology, cambial phenology, and wood formation patterns, which result in different treering widths (TRWs) and wood anatomy. Chronologies of tree ring width and vessel features [i.e., mean vessel area (MVA), vessel density (VD), and relative conductive area (RCTA)] were produced for the 1960%2016 period for three sites that differ in climatic regimes and spring leaf phenology (two early- and one late-flushing populations). These data were used to investigate long-term relationships between climatic conditions and anatomical features of four quarters of tree-rings at annual and intra-annual scales. In addition, we investigated how TRW and vessel features adjust in response to extreme weather events (i.e., summer drought). We found significant differences in TRW, VD, and RCTA among the selected sites. Precipitation and maximum temperature before and during the growing season were the most important climatic factors affecting TRW and vessel characteristics. We confirmed differences in climate-growth relationships between the selected sites, late flushing beech population at Idrija showing the least pronounced response to climate. MVA was the only vessel trait that showed no relationship with TRW or other vessel features. The relationship between MVA and climatic factors evaluated at intra-annual scale indicated that vessel area in the first quarter of tree-ring were mainly influenced by climatic conditions in the previous growing season, while vessel area in the second to fourth quarters of tree ring width was mainly influenced by maximum temperature and precipitation in the current growing season. When comparing wet and dry years, beech from all sites showed a similar response, with reduced TRW and changes in intra-annual variation in vessel area. Our findings suggest that changes in temperature and precipitation regimes as predicted by most climate change scenarios will affect tree-ring increments and wood structure in beech, yet the response between sites or populations may differ.
Ključne besede: Fagus sylvatica, wood anatomy, tracheograms, dendrochronology, intra specific plasticity
Objavljeno v DiRROS: 22.07.2022; Ogledov: 186; Prenosov: 131
.pdf Celotno besedilo (15,28 MB)
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Modelling seasonal dynamics of secondary growth in R
Jernej Jevšenak, Jožica Gričar, Sergio Rossi, Peter Prislan, 2022, izvirni znanstveni članek

Povzetek: The monitoring of seasonal radial growth of woody plants addresses the ultimate question of when, how and why trees grow. Assessing the growth dynamics is important to quantify the effect of environmental drivers and understand how woody species will deal with the ongoing climatic changes. One of the crucial steps in the analyses of seasonal radial growth is to model the dynamics of xylem and phloem formation based on increment measurements on samples taken at relatively short intervals during the growing season. The most common approach is the use of the Gompertz equation, while other approaches, such as general additive models (GAMs) and generalised linear models (GLMs), have also been tested in recent years. For the first time, we explored artificial neural networks with Bayesian regularisation algorithm (BRNNs) and show that this method is easy to use, resistant to overfitting, tends to yield s-shaped curves and is therefore suitable for deriving temporal dynamics of secondary tree growth. We propose two data processing algorithms that allow more flexible fits. The main result of our work is the XPSgrowth() function implemented in the radial Tree Growth (rTG) R package, that can be used to evaluate and compare three modelling approaches: BRNN, GAM and the Gompertz function. The newly developed function, tested on intra-seasonal xylem and phloem formation data, has potential applications in many ecological and environmental disciplines where growth is expressed as a function of time. Different approaches were evaluated in terms of prediction error, while fitted curves were visually compared to derive their main characteristics. Our results suggest that there is no single best fitting method, therefore we recommend testing different fitting methods and selection of the optimal one.
Ključne besede: artificial neural networks, cambium, generalized additive model, Gompertz function, growing season, intra-annual time series
Objavljeno v DiRROS: 21.07.2022; Ogledov: 176; Prenosov: 132
.pdf Celotno besedilo (1,26 MB)
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