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Query: "author" (Urša Vilhar) .

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31.
Green water reconstructed for Rižana watershed, SW Slovenia
Simon Poljanšek, Urša Vilhar, Tom Levanič, original scientific article

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
Published in DiRROS: 18.04.2018; Views: 2733; Downloads: 1614
.pdf Full text (1003,43 KB)
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Influence of meteorological conditions and crown defoliation on tree phenology in intensive forest monitoring plots in Slovenia
Urša Vilhar, Mitja Skudnik, Mitja Ferlan, Primož Simončič, 2014, original scientific article

Abstract: Data from the forest monitoring programme in Slovenia were used to assess the relationship between tree phenology, crown defoliation and meteorological conditions in Fagus sylvatica, Quercus robur and Picea abies forests in the 2004-2013 period. We hypothesized a species-specific response of first leaf unfolding, general leaf colouring, the length of the growing season to crown defoliation, air temperature, precipitation and soil water. In accordance with the hypothesis, we found a high sensitivity of first leaf unfolding to air temperature and precipitation for all species, exhibiting contrasting responses. We observed strong sensitivity of beech defoliation to precipitation and soil water conditions. Oak crown defoliation and next-year phenology were correlated, with higher crown defoliation contributing to earlier leaf unfolding, later autumn leaf colouring and longer growing season of oak in next year. Correlation between crown defoliation and phenology was found neither for beech nor spruce.
Published in DiRROS: 12.07.2017; Views: 4320; Downloads: 2316
.pdf Full text (1,35 MB)

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Fenološke faze dreves na ploskvah intenzivnega monitoringa gozdnih ekosistemov v Sloveniji
Urša Vilhar, Mitja Skudnik, Primož Simončič, 2013, original scientific article

Abstract: Preučevanje razvojnih faz gozdnega drevja v dolgem časovnem nizu je vse pomembnejše orodje za ugotavljanje medsebojne odvisnosti vremenskih spremenljivk in z njimi povezanih bioloških odzivov. V naši raziskavi smo analizirali nastop fenofaz prvih listov in iglic ter splošnega rumenenja listja za listavce na 11 ploskvah intenzivnega monitoringa gozdnih ekosistemov v Sloveniji v letih od 2004 do 2011. Obravnavali smo fenofaze za dob (Quercus robur L.) na ploskvah Krakovski gozd in Murska šuma; bukev (Fagus sylvatica L.) na ploskvah Lontovž pod Kumom, Temenjak na Vinski gori, Borovec v Kočevski Reki, Fondek v Trnovskem gozdu, Gorica v Loškem Potoku; smreko (Picea abies (L.) Karst.) na ploskvah Kladje na Pohorju in Krucmanove Konte na Pokljuki; rdeči bor (Pinus sylvestris L.) na ploskvi Brdo pri Kranju; črni bor (Pinus nigra Arnold) na ploskvi Gropajski Bori pri Sežani. V povprečju je fenofaza prvih iglic (BGS) smreke nastopila na 166 julijanski dan. Za rdeči bor je BGS nastopila na 128 julijanski dan, za črni bor pa 149. julijanski dan. Fenofaza prvih listov (BGS) je za bukev v povprečju nastopila na 128, za dob pa 117. julijanski dan. Splošno rumenenje listov (EGS) za bukevje v povprečju nastopilo na 297, za dob pa 308. julijanski dan. Dolžina vegetacijskega obdobja (LGS) doba je bila v povprečju 75 dni daljša kot za bukev. Ugotavljamo, da se je v obdobju od leta 2004 do 2011 nakazoval zgodnejši nastop fenofaze prvih iglic (BGS) smreke, rdečega bora ter črnega bora na vseh obravnavanih ploskvah. Zgodnejši nastop prvih listov (BGS) bukve in doba smo zaznali le na posameznih ploskvah, ne pa vseh. Kasnejši nastop splošnega rumenenja listov (EGS) za bukev smo zaznali le na dveh ploskvah (Borovec in Gorica), za dob pa smo ugotovili kasnejše pojavljanje EGS le na ploskvi Murska Šuma. Značilna je velika variabilnost dolžine vegetacijskega obdobja (LGS) za bukev in dob po letih. Daljšanje LGS za bukev je statistično značilno za tri ploskve (Fondek, Borovec in Gorica), za dob pa spremembe LGS v opazovanem obdobju niso bile statistično značilne.
Keywords: gozdovi, fenologija, monitoring, gozdni ekosistemi, Slovenija
Published in DiRROS: 12.07.2017; Views: 4676; Downloads: 2314
.pdf Full text (917,15 KB)

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Padavinski režim v izbranih vrzelih in sestojih dinarskega jelovo-bukovega gozda
Urša Vilhar, 2010, original scientific article

Abstract: Količina, oblika in časovna razporeditev padavin so izrednega pomena za gozdneekosisteme, saj pomembno vplivajo na preskrbo z vodo, kroženje hranil indinamiko ogljika v ekosistemu. Namen naše raziskave je bil analizirati padavinski režim v dveh sestojih in vrzelih različne velikosti v dinarskem jelovo-bukovem pragozdnem rezervatu Rajhenavski Rog ter v gospodarskem sonaravnem gozdu Snežna jama. V vegetacijskem obdobju v letih 2003 in 2004 smospremljali prepuščene padavine in odtok po deblu v vrzelih in sestojih, padavine na prostem pa v letih od 2001 do 2007. Meritve padavin v gozdni krajini so redke, čeprav so pomemben vhodni podatek za modeliranje procesov v gozdnih ekosistemih. Uporaba meritev z najbližjih meteoroloških postaj je zaradi njihove oddaljenosti vprašljiva, zato smo dnevne in mesečne količine padavin na prostem primerjali z vrednostmi za klimatološko postajo Kočevje ter EMEP-postajo Iskrba pri Kočevski Reki.
Keywords: padavine, vrzeli, gozdovi, gospdoarski gozdovi, pragozdovi, pragozdni rezervati, Kočevski Rog
Published in DiRROS: 12.07.2017; Views: 4493; Downloads: 1915
.pdf Full text (531,04 KB)

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Mikroklimatske razmere v vrzelih in sestojih dinarskega jelovo-bukovega gozda
Urša Vilhar, Primož Simončič, Lučka Kajfež-Bogataj, Klaus Katzensteiner, Jurij Diaci, 2006, original scientific article

Abstract: Mikroklimatske razmere sodijo med dejavnike, ki odločujoče vplivajo na zgradbo, rast, zdravstveno stanje in stabilnost gozdnih ekosistemov. Namen naše raziskave je bil raziskati osnovne mikroklimatske razmere v dveh sestojihin v vrzelih različne velikosti v dinarskem jelovo-bukovem pragozdnem rezervatu (Rajhenavski Rog) ter gospodarskem sonaravnem gozdu (Snežna jama) v vegetacijskem obdobju v letih 2003 in 2004. Spremljali smo temperaturo zraka, temperaturo tal, relativno zračno vlago ter smer in hitrost vetra. V pragozdnem rezervatu so bile povprečne dnevne temperature zraka na 2 m višine nižje kot v gospodarskem gozdu, relativna zračna vlaga pa je bila višja. V gospodarskem gozdu so bile v nasprotju s pričakovanji temperature zraka na sredini Male vrzeli (SMV) višje kot na sredini Velike vrzeli (SVV). Ugotavljamo, da na mikroklimatske razmere poleg zgradbe sestoja in oblikovanost roba vrzeli pomembno vplivajo tudi značilnosti razgibanega kraškega reliefa: naklon terena, ekspozicija ter oblikovanost terena.
Keywords: mikroklima gozda, gospodarski gozd, pragozdni rezervati, vrzeli, tvorba vrzeli, Kočevski Rog
Published in DiRROS: 12.07.2017; Views: 4371; Downloads: 1816
.pdf Full text (3,79 MB)

40.
Biodiversity of types of ectomycorrhizae in a norway spruce stands on Pokljuka
Urša Vilhar, Igor Smolej, Tadeja Trošt Sedej, Lado Kutnar, Hojka Kraigher, 2004, original scientific article

Abstract: Types of ectomycorrhizae were studied in soil cores from a young regeneration center in an autochthonous Norway spruce stand on Pokljuka (Triglav National Park, 1200 m.a.s.l.). Soil cores of equal volume (274 ml, 0 - 18 cm deep) weretaken from 33 sampling plots. In the samples all the roots were counted and types of ectomycorrhizae briefly characterized. From these data diversity indices (species diversity (d) and Shannon- Weaver index of diversity (H)) were calculated. Interactions among mycorrhizae, light regime and survival of spruce seedlings were studied. Out of about 50,000 root tips approximately 1 %were non-mycorrhizal, 63 % were old unviable mycorrhizae and 36 % were identifiable ectomycorrhizal root tips, forming 27 different types of ectomycorrhizae. Sixteen types of ectomycorrhizae were briefly characterized. The Shannon diversity index for types of ectomycorrhizae was high (3.13) with respect to the above-ground diversity of vegetation (1.7). The direct site factor was shown to be negatively correlated to ~Piceirhiza cornuta. The diffuse site factor was negatively correlated to Cortinarius sp. (obtusus type) and positively correlated to Inocybe sp. The ground vegetation cover waspositively correlated to Piceirhiza gelatinosa and the total vegetation cover to Elaphomyces sp.
Keywords: ectomycorrhizae, types of ectomycorrhizae, Norway spruce, natural regeneration, Pokljuka
Published in DiRROS: 12.07.2017; Views: 4235; Downloads: 1840
.pdf Full text (1,79 MB)

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