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Resin yield of Pinus nigra and Pinus sylvestris in the Slovenian Karst
Robert Brus, Kristjan Jarni, Miha Brecelj, Domen Gajšek, 2018

Povzetek: The aim of our research was to study the impact of various environmental factors on the resin production of pines in the Slovenian Karst. Five plots were established % three in Pinus nigra (Arnold) stands and two in Pinus sylvestris (L.) stands. On each plot, the 19-20 most vigorous dominant or codominant trees with a minimum diameter at breast height (DBH) of 20 cm were selected and their resin yield analysed in 2012. Resin yield in P. nigra was considerably higher than that in P. sylvestris. The average resin yield per tree during the study period of 102 days was 1.144 kg for P. nigra and 0.612 for P. sylvestris. There were substantial differences in resin yield among individual trees in the study period: 0.336-2.487 kg for P. nigra and 0.249-1.270 kg for P. sylvestris. The resin yield in P. nigra was considerably higher for the trees with larger DBH, while this was not the case in P. sylvestris. Tree species was the most important factor in resin yield. Increased precipitation resulted in higher resin yields on most plots, whereas better site productivity positively affected resin yield on all P. nigra plots but not on P. sylvestris plots.
Ključne besede: Black pine, Scots pine, resin production, resin yield, Slovenian Karst
DiRROS - Objavljeno: 05.07.2018; Ogledov: 999; Prenosov: 174
.pdf Celotno besedilo (1,78 MB)

Phytosociological description of mesophilous colline-submontane Fagus sylvatica and Carpinus betulus forests in Slovenian Istria
Zvone Sadar, Igor Dakskobler, 2018

Povzetek: A phytosociological analysis of 46 relevés of mesophilous colline and submontane Fagus sylvatica as well as (or) Carpinus betulus forests was conducted in Slovenian Istria. It was established that they are frequently syndynamically interrelated: in places, common hornbeam stands are merely a degradation stage on beech sites, and can be classified into the subassociation Ornithogalo pyrenaici-Fagetum fraxinetosum orni (its locus classicus is in the Goriška Brda Hills) and into the new subassociation Ornithogalo pyrenaici-Carpinetum betuli seslerietosum autumnalis. Compared with similar submontane stands from other parts of the western and southwestern Slovenia they are slightly poorer in species, with fewer diagnostic species of alliances Erythronio-Carpinion, Aremonio-Fagion and Tilio-Acerion, order Fagetalia sylvaticae and class Vaccinio-Piceetea, and with more diagnostic species of the order Quercetalia pubescenti-petraeae. Geographically, they are characterised by the taxon Helleborus odorus subsp. istriacus. Although they cover small areas these forests generate high yields and are therefore important both economically and as biotopes of protected species.
Ključne besede: phytosociology, synsystematics, beech sites, Ornithogalo-Carpinetum, Ornithogalo-Fagetum, Istria, Slovenia
DiRROS - Objavljeno: 15.06.2018; Ogledov: 1055; Prenosov: 399
.pdf Celotno besedilo (3,43 MB)Gradivo je zbirka in zajema 1 gradivo!

Genetic diversity of core vs. peripheral Norway spruce native populations at a local scale in Slovenia
Hojka Kraigher, Gregor Božič, Marjana Westergren

Povzetek: We investigated the levels of genetic diversity and population differentiation among core and peripheral populations of Norway spruce along an altitudinal gradient (from inversions to upper tree line) using isoenzymes (ISO) and nuclear simple-sequence repeats (SSR) markers on overlapping set of populations. Twenty-seven to seventy trees from 11 and 7 populations were genotyped with isoenzymes and SSRs, respectively. The results partially conform to the expectations of the central-peripheral hypothesis (CPH) and are consistent for both marker sets. Genetic differentiation among peripheral populations was low but significantly different from zero (FST-ISO = 0.013, FST-SSR = 0.009) and higher than that among core populations (FST-ISO = 0.007, FST-SSR = 0.005), conforming to central peripheral hypothesis. Contrastingly, levels of genetic diversity assessed by both richness and equitability measures did not significantly differ between peripheral and core populations (AR-ISO = 2.20 vs. 2.14, AR-SSR = 17.16 vs. 17.68, HE-ISO = 0.183 vs. 0.185, and HE-SSR = 0.935 vs. 0.935 for peripheral and core populations, respectively).
Ključne besede: central peripheral hypothesis, Picea abies (L.) Karst., genetic diversity, genetic differentiation, upper tree line, inversion
DiRROS - Objavljeno: 07.05.2018; Ogledov: 881; Prenosov: 292
.pdf Celotno besedilo (561,16 KB)

Green water reconstructed for Rižana watershed, SW Slovenia
Tom Levanič, Urša Vilhar, Simon Poljanšek

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
DiRROS - Objavljeno: 18.04.2018; Ogledov: 892; Prenosov: 256
.pdf Celotno besedilo (1003,43 KB)

Growth response of different tree species (oaks, beech and pine) from SE Europe to precipitation over time
Saša Orlović, Stefan Stjepanović, Bratislav Matović, Tom Levanič, Dejan Stojanović

Povzetek: Changing climatic conditions can have various consequences for forest ecosystems, from increasing frequencies of forest fires, ice and windstorm events to pathogen outbreaks and mass mortalities. The Standardized Precipitation Index (SPI) was chosen for the evaluation of drought impact on the radial growth of trees after extensive preliminary testing of various calculated monthly climate parameters from the CARPATCLIM database. SPI was calculated for periods between 3 and 36 months for different sites (lowland and mountainous parts of Serbia, Southeast Europe), from which Quercus robur, Q. cerris, Fagus sylvatica and Pinus sylvestris samples were acquired. Bootstrapped Pearson%s correlations between SPI monthly indices and radial growth of tree species were calculated. We found that 12-month SPI for summer months may be a good predictor of positive and negative growth of different species at different sites. The strongest positive correlations for five of six tree-ring width chronologies were between 12-month June and 14-month September SPI, which implies that high growth rates can be expected when the autumn of the previous year, and winter, spring and summer of the current year, are well supplied with precipitation, and vice versa (low precipitation in given period/low growth rates).
Ključne besede: standardized precipitation index, SPI, climate change, tree mortality, Quercus sp., Fagus sylvatica, Pinus sylvestris
DiRROS - Objavljeno: 18.04.2018; Ogledov: 1007; Prenosov: 244
.pdf Celotno besedilo (2,91 MB)

DendroTools : R package for studying linear and nonlinear responses between tree-rings and daily environmental data
Tom Levanič, Jernej Jevšenak

Povzetek: We introduce in this paper the dendroTools R package for studying the statistical relationships between tree-ring parameters and daily environmental data. The core function of the package is daily_response(), which works by sliding a moving window through daily environmental data and calculating statistical metrics with one or more tree ring proxies. Possible metrics are correlation coefficient, coefficient of determination and adjusted coeffi- cient of determination. In addition to linear regression, it is possible to use a nonlinear artificial neural network with the Bayesian regularization training algorithm (brnn). dendroTools provides the opportunity to use daily climate data and robust nonlinear functions for the analysis of climate-growth relationships. Models should thus be better adapted to the real (continuous) growth of trees and should gain in predictive capabilities. The dendroTools R package is freely available in the CRAN repository. The functionality of the package is demonstrated on two examples, one using a mean vessel area (MVA) chronology and one a traditional tree-ring width (TRW).
Ključne besede: dendroclimatology, daily climate data, running window, nonlinear modelling, tree-ring proxies, climate reconstruction
DiRROS - Objavljeno: 16.04.2018; Ogledov: 1029; Prenosov: 252
.pdf Celotno besedilo (1,19 MB)

Occurrence of invasive alien plant species in the floodplain forests along the Mura River in Slovenia
Lado Kutnar, Aleksander Marinšek

Povzetek: Background and purpose: The objectives of our study were to identify invasive alien plant species (IAS) in the main Natura 2000 forest habitat types (FHT) along the Mura River in Slovenia, and to estimate their abundance and cover. The aim of our study was to find out a) Which IAS appear in the research forests? b) What is their frequency and cover percentage? c) Whether individual IAS prosper better in some FHT than others? d) What is the correlation between the cover of IAS and the tree layer cover? Materials and methods: We analysed the fidelity of invasive plant species to individual FHT. The studied FHTs along the Mura River were the following: 91E0* (Alluvial forests with Alnus glutinosa and Fraxinus excelsior), 91F0 (Riparian mixed forests of Quercus robur, Ulmus laevis and Ulmus minor, Fraxinus excelsior or Fraxinus angustifolia, along the great rivers) and 91L0 (Illyrian oak-hornbeam forests). Two forest areas of about 600 ha were studied in total. With the intention to calculate number and cover of IAS some statistical analysis was made. In addition, correlations between the abundances of the most present IAS and cover of upper tree layer were carried out. Results: In total, 15 IAS were recorded in studied FHTs. Some species, like Robinia pseudoacacia, Impatiens glandulifera, I. parviflora, Fallopia japonica (incl. F. x bohemica), Erigeron annuus, Ambrosia artemisiifolia, Amorpha fruticosa, Conyza canadensis and Juncus tenuis occur only in one or two FHTs, while some species can be found in all studied FHTs (e.g. Solidago sp.). We found out that the most threatened forests are those with prevailing Salix alba, Alnus glutinosa, Fraxinus angustifolia and Ulmus laevis tree species. Those are the forests of FHT 91E0 which have less dense tree canopies, grow closest to the river and on the wettest sites. We found a statistically significant higher number and cover of IAS in the FHT 91E0 and the lowest number and cover in FHT 91L0. Conclusions: Alluvial forests with Alnus glutinosa and Fraxinus excelsior (FHT 91E0) along the Mura River are most prone to invasion of IAS. The increasing presence of IAS in the study areas seriously affects natural regeneration, stability, and continuity of floodplain forests in all other FHTs in the study area. At the same time the amount of IAS in these forests also depends on management measures and their intensities which accelerate light availability. Some measures and guidelines for managing of these forests with the purpose of reducing IAS impacts are suggested in this study.
Ključne besede: non-native plants, riparian vegetation, habitat types, conservation management, forest management
DiRROS - Objavljeno: 16.04.2018; Ogledov: 898; Prenosov: 254
.pdf Celotno besedilo (1,03 MB)

Prehod kovin iz tal v tkiva izbranih vrst prostoživečih živali : primer Velikega Vrha
Boris Kryštufek, Davorin Tome, Boštjan Pokorny, Nataša Kopušar, Samar Al Sayegh-Petkovšek, 2017

Povzetek: V raziskavi smo analizirali prenos kovin iz gozdnih in travniških tal v male sesalce (rumenogrla miš, gozdna in poljska voluharica), veliko sinico in lisico, ki živijo na območju Velikega Vrha. Hkrati smo ocenili tveganje za te organizme na podlagi primerjave določenih vsebnosti v rastlinskih in živalskih tkivih s kritičnimi ter dopustnimi vsebnostmi in izračunom kvocienta tveganja (HQ) na podlagi vnosa kovin s prehrano. Izjema je bila velika sinica, ki smo jo pri izračunu HQ nadomestili s kosom, ki se pogosto prehranjuje z deževniki. Ugotovili smo, da so gozdni in travniški ekosistemi na območju Velikega Vrha, ki je bil zlasti v preteklosti izpostavljen velikim izpustom iz Termoelektrarne Šoštanj, zmerno obremenjeni s Pb (gozdna tla, živalska tkiva), Hg (gozdna tla, živalska tkiva) in Cd (travniška tla, korenine trav, detelj in zeli). Vendar tveganja za prostoživeče živali (navadna lisica, rumenogrla miš, poljska in gozdna voluharica) in deževnike nismo ugotovili, saj so bile določene vsebnosti Hg, Pb in Cd nižje od kritičnih (mali sesalci, lisica) oziroma letalnih (smrtnih) vsebnosti (deževniki). Obstaja pa verjetnost za tveganje zaradi vnosa Hg v lisico prek gozdne voluharice in zaradi vnosa Pb v kosa prek deževnikov, vendar samo v primeru, če bi ta prehranska vira sestavljala vsaj polovico diete omenjenih organizmov.
Ključne besede: kovine, termoelektrarna, Hg, Pb, mali sesalci, velika sinica, ocena tveganja
DiRROS - Objavljeno: 21.02.2018; Ogledov: 1303; Prenosov: 134
.pdf Celotno besedilo (1,21 MB)

Uporaba metod strojnega učenja za preučevanje odnosov med značilnostmi branik in okoljem
Tom Levanič, Sašo Džeroski, Jernej Jevšenak, 2017

Povzetek: Različne študije so pokazale, da lahko z nelinearnimi metodami bolje opišemo (modeliramo) odnos med branikami in okoljem. V naši študiji smo primerjali (multiplo) linearno regresijo (MLR) in štiri nelinearne metode strojnega učenja: modelna drevesa (MT), ansambel bagging modelnih dreves (BMT), umetne nevronske mreže (ANN) in metodo naključnih gozdov (RF). Za primerjavo teh metod modeliranja smo uporabili štiri množice podatkov. Natančnost naučenih modelov smo ocenili z metodo 10-kratnega prečnega preverjanja (ang. 10-fold cross-validation) na naši množici in preverjanjem na dodatni testni množici. Na vseh množicah smo dobili boljše statistične kazalce za nelinearne metode s področja strojnega učenja, s katerimi lahko pojasnimo večji delež variance oz. dobimo manjšo napako. Nobena metoda se ni pokazala kot najboljša v vseh primerih, zato je smiselno predhodno primerjati več različnih metod in nato uporabiti najprimernejšo, npr. za rekonstrukcijo klime.
Ključne besede: strojno učenje, primerjava metod, dendroklimatologija, umetne nevronske mreže, modelna drevesa, ansambel modelnih dreves, naključni gozdovi, linearna regresija
DiRROS - Objavljeno: 21.02.2018; Ogledov: 1095; Prenosov: 204
.pdf Celotno besedilo (1,18 MB)

Poslovno povezovanje lastnikov gozdov na primeru Društva lastnikov gozdov Pohorje-Kozjak
Tomislav Laktić, Špela Pezdevšek Malovrh, 2017

Povzetek: Večina ključnih problemov gospodarjenja z zasebnimi gozdovi izhaja iz majhne in razdrobljene gozdne posesti, ki je v lasti velikega števila lastnikov. Zato je njihovo povezovanje ključno za bolj učinkovito gospodarjenje. Največji razmah so v zadnjih letih doživela društva lastnikov gozdov, ki so po Zakonu o društvih opredeljena kot samostojno in nepridobitno združenje. Kot odgovor temu se je med člani pokazala težnja po nadgradnji takšne oblike povezovanja v smeri poslovnega povezovanja. V prispevku je predstavljeno Društvo lastnikov gozdov Pohorje-Kozjak kot primer dobre prakse širitve z društvenih aktivnosti na raven poslovnega (zadružnega) sodelovanja. Na vzorcu članov društva in zadruge je bila opravljena anketa o poslovnem povezovanju in možnostih profesionalizacije dela. Za poslovno povezovanje so bolj pripravljeni mlajši lastniki gozdov večjih gozdnih posesti z višjo stopnjo izobrazbe. Člani društva in zadruge so naklonjeni poslovnemu povezovanju in profesionalizaciji, vendar sami nočejo nositi finančnega bremena. Pri tem si želijo pomoči države v smislu finančnih spodbud za podporo dobrim praksam in profesionalizaciji dela.
Ključne besede: zasebni gozdovi, povezovanje zasebnih lastnikov gozdov, društvo lastnikov gozdov, gozdarska zadruga, profesionalizacija aktivnosti
DiRROS - Objavljeno: 25.10.2017; Ogledov: 1407; Prenosov: 205
.pdf Celotno besedilo (675,26 KB)

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