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Iskalni niz: "avtor" (Simon Poljanšek) .

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1.
Can urban trees provide reliable proxies for climate reconstructions?
Saša Zavadlav, Simon Poljanšek, Lena Marion, Tom Levanič, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Objavljeno v DiRROS: 03.11.2021; Ogledov: 336; Prenosov: 131
.pdf Celotno besedilo (4,38 MB)

2.
Climate signal and potential of Bosnian pine (Pinus heldreichii Christ) for climate reconstruction in Central W Balkan region
Tom Levanič, Simon Poljanšek, Dalibor Ballian, 2015, objavljeni povzetek znanstvenega prispevka na konferenci

Objavljeno v DiRROS: 03.11.2021; Ogledov: 288; Prenosov: 119
.pdf Celotno besedilo (1,05 MB)

3.
Seasonal radial growth of Black pine (Pinus nigra Arnold) from Bosnia and Herzegovina, monitored by the pinning method and manual band dendrometers
Simon 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: 2900; Prenosov: 2685
.pdf Celotno besedilo (2,14 MB)
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4.
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Green water reconstructed for Rižana watershed, SW Slovenia
Simon Poljanšek, Urša Vilhar, Tom Levanič, izvirni znanstveni članek

Povzetek: In this case study, set in south-west Slovenia, the feasibility of reconstructing green water (the combined amount of evaporated and transpired water in trees and available in the soil) was investigated. In a simplifed scheme, the amounts of green water were calculated as the diference between precipitation and discharge of the Rižana river. Based on the methods of dendroclimatology, the climate signal was tested on black pine (Pinus nigra Arnold) trees growing in the south-western part of the Rižana watershed near the Slovenian sea coast. Results showed that the measured tree-ring parameters of tree-ring width and density are strongly dependent on the amount of green water. The strongest correlation was between available green water in the period May-August and tree-ring width (r=0.61) and latewood width (r=%0.64) (both n=46, p<0.001). The climate signal is signifcant and stable through time, which enabled the reconstruction of green water data into the period before instrumentally measured data. Green water data from the May-August period were extended from 1966 back to 1937 using tree-ring width, and back to 1940 using latewood width. With additional coring of older trees and the extension of existing chronologies, even longer reconstructions could be developed.
Ključne besede: tree-ring width, tree-ring density, dendrochronology, dendroclimatology, reconstruction
Objavljeno v DiRROS: 18.04.2018; Ogledov: 2260; Prenosov: 1162
.pdf Celotno besedilo (1003,43 KB)
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6.
Multiple tree-ring parameters from Pinus nigra (Arnold) and their climate signal
Simon Poljanšek, Tom Levanič, 2012, izvirni znanstveni članek

Povzetek: The first exploration of climate signal in tree-rings of Black pine (P. nigra Arnold), using minimum blue intensity method, is presented. Sampled trees were growing on site Kojnik (Slovenia). For resin extraction and scanning, 5 mm thick cores were prepared. Whole tree-ring widths were measured, as well as the width and density of early- and latewood. To remove age trend and influence of non-climatic factors, raw measurements were standardized using spline function. In density measurements, highly significant correlation values were calculated between May-June summed precipitation and earlywood density (r = 0.64, p<0.001), while maximum latewood density correlates the best with mean June-August temperature (r = 0.42, p<0.01). In width measurements, the highest correlation was calculated between tree-ring width and mean June-August temperature (r = -0.62, p<0.001).
Objavljeno v DiRROS: 12.07.2017; Ogledov: 3029; Prenosov: 1522
.pdf Celotno besedilo (951,14 KB)

7.
Metoda preučevanja sledi iglic terminalnega poganjka
Simon Poljanšek, Primož Oven, Risto Jalkanen, Tom Levanič, 2011, pregledni znanstveni članek

Povzetek: Metoda preučevanja sledi iglic terminalnega poganjka, ali krajše metoda sledi iglic (ang.: needle trace method), retrospektivno beleži starost iglice v trenutku, ko odpade, ter preučuje vpliv okoljskih in biotskih dejavnikov na številne izpeljane podatke, ki temeljijo na ugotovljeni življenjski dobi iglice. Z izvedbo metode pridobimo podatke o dolžini višinskih prirastkov ter številu sledi iglic v posameznih branikah vseh višinskih prirastkov. Z izračunanimi kazalniki je mogoče oceniti fizično stanje krošnje preučevanega drevesa. Metoda je bila razvita na Finskem na rdečem boru (Pinus sylvestris L.), kmalu pa uporabljena tudi na drugih iglavcih. Uporablja se na področju dendrokronologije, gozdne ekologije, patologije in entomologije. V članku avtorji predstavljajo osnovno morfologijo sledi iglic, osnovno idejo metode in njeno uporabnost v okoljskih študijah ter izpeljane kazalnike, kot so relativno število sledi iglic ter zadrževanje, izguba, odmet, starost, dolgoživost, gostota, letni prirast števila in zaloga iglic.
Ključne besede: iglavci, iglice, rdeči bor, Pinus spp., listni aparat, kazalniki, okolje, onesnaževanje, defioliacija
Objavljeno v DiRROS: 12.07.2017; Ogledov: 3132; Prenosov: 1391
.pdf Celotno besedilo (1,05 MB)

8.
Primerjava programov za standardizacijo časovnih vrst v dendrokronologiji
Simon Poljanšek, Špela Jagodic, Tom Levanič, 2010, izvirni znanstveni članek

Povzetek: Za standardizacijo zaporedij širin branik je v uporabi več programov, mi smo primerjali dva - najbolj razširjeni in znani program ARSTAN in pred kratkim predstavljeno knjižnico za standardizacijo dendrokronoloških podatkov dplR, narejeno za statistični program R. Oba programa sta brezplačna, ARSTAN je namenski program za standardizacijo zaporedij širin branik, medtem ko je program R, v okviru katerega deluje knjižnica dplR, namenjen tudi drugim analizam in prikazom podatkov. Uporabili smo različne teste in preverili, ali so med kronologijami širin branik, kakor jih izračunata ARSTAN in dplR, statistično značilne razlike in ali so standardizirane kronologije, narejene s knjižnico dplR, enako uporabne za preučevanje ekoloških in klimatoloških vprašanj, kot so kronologije, narejene s programom ARSTAN. ARSTAN za izračun kronologije ponudi uporabniku listo ukazov, medtem ko dplR zahteva pisne ukaze in ne ponuja izbire. Pri primerjavi rezultatov smo ugotovili, da razlike med izračuni primerjanih programov niso statistično značilne - programa pri osnovnih statističnih parametrih ponudita enake rezultate za povprečne širine branik in standardne odklone ter z razliko na drugem decimalnem mestu za rezultate občutljivosti in avtokorelacijskega koeficienta. Korelacija med standardiziranima kronologijama znaša 0,9773, med kronologijama ostankov pa 0,9776, grafično so razlike prav tako maloštevilne in majhne. Ker se programa razlikujeta le po delovnem okolju, je odločitev o izbiri programa prepuščena uporabniku.
Ključne besede: dendrokronologija, računalniški programi, ARSTAN, dplR, branike, kronologija širine branik
Objavljeno v DiRROS: 12.07.2017; Ogledov: 2959; Prenosov: 1237
.pdf Celotno besedilo (352,54 KB)

9.
Overview of dendroclimatological studies in the Balkan peninsula
Simon Poljanšek, Tom Levanič, 2015, izvirni znanstveni članek

Objavljeno v DiRROS: 12.07.2017; Ogledov: 2343; Prenosov: 936
.pdf Celotno besedilo (138,72 KB)
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10.
Stres dreves v mestnem okolju
Simon Poljanšek, 2015, strokovna monografija

Ključne besede: mestno drevje, urbano gozdarstvo, okoljski dejavniki, abiotski dejavniki, biotski dejavniki
Objavljeno v DiRROS: 12.07.2017; Ogledov: 2427; Prenosov: 698
.pdf Celotno besedilo (8,50 MB)

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