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Query: "author" (Simon Poljanšek) .

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1.
2.
Long-term summer sunshine/moisture stress reconstruction from tree-ring widths from Bosnia and Herzegovina
Simon Poljanšek, Andrej Ceglar, Tom Levanič, 2013

DiRROS - Published: 12.07.2017; Views: 1016; Downloads: 262
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3.
Dendroclimatological investigation of Black pine trees (Pinus nigra a.) from hilly coastal area of Croatia
Simon Poljanšek, Tom Levanič, Stjepan Mikac, 2015

DiRROS - Published: 12.07.2017; Views: 798; Downloads: 98
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Stres dreves v mestnem okolju
Simon Poljanšek, 2015

Keywords: mestno drevje, urbano gozdarstvo, okoljski dejavniki, abiotski dejavniki, biotski dejavniki
DiRROS - Published: 12.07.2017; Views: 1007; Downloads: 79
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6.
Overview of dendroclimatological studies in the Balkan peninsula
Simon Poljanšek, Tom Levanič, 2015

DiRROS - Published: 12.07.2017; Views: 1032; Downloads: 277
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7.
Primerjava programov za standardizacijo časovnih vrst v dendrokronologiji
Simon Poljanšek, Špela Jagodic, Tom Levanič, 2010

Abstract: 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.
Keywords: dendrokronologija, računalniški programi, ARSTAN, dplR, branike, kronologija širine branik
DiRROS - Published: 12.07.2017; Views: 886; Downloads: 67
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8.
Metoda preučevanja sledi iglic terminalnega poganjka
Simon Poljanšek, Primož Oven, Risto Jalkanen, Tom Levanič, 2011

Abstract: 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.
Keywords: iglavci, iglice, rdeči bor, Pinus spp., listni aparat, kazalniki, okolje, onesnaževanje, defioliacija
DiRROS - Published: 12.07.2017; Views: 969; Downloads: 109
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9.
Multiple tree-ring parameters from Pinus nigra (Arnold) and their climate signal
Simon Poljanšek, Tom Levanič, 2012

Abstract: 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).
DiRROS - Published: 12.07.2017; Views: 1008; Downloads: 216
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10.
Green water reconstructed for Rižana watershed, SW Slovenia
Tom Levanič, Urša Vilhar, Simon Poljanšek

Abstract: 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.
Keywords: tree-ring width, tree-ring density, dendrochronology, dendroclimatology, reconstruction
DiRROS - Published: 18.04.2018; Views: 895; Downloads: 258
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