151. Mnenje Oddelka za gozdarstvo in obnovljive gozdne vire o sečnji na RožnikuKlemen Jerina, Andrej Bončina, Jurij Diaci, Janez Pirnat, Robert Brus, Dušan Roženbergar, Tine Hauptman, Janez Krč, 2023, polemika, diskusijski prispevek, komentar Ključne besede: sečnja, urbani gozdovi, mestni gozdovi, Ljubljana, Tivoli, Rožnik
Objavljeno v DiRROS: 19.04.2023; Ogledov: 477; Prenosov: 99
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153. Stable isotope composition in tree rings of Fagus sylvatica L. saplings reflects environmental variation induced by silviculture and microsite factorsJanez Kermavnar, Tom Levanič, Lado Kutnar, 2023, izvirni znanstveni članek Povzetek: Natural regeneration of tree species is sensitive to silvicultural interventions. This study aimed to investigate the effects of different cutting intensities and local topographic and soil conditions on the composition of stable carbon (δ13C) and oxygen (δ18O) isotopes in wood of young beech (Fagus sylvatica L.) trees. Beech saplings in the regeneration layer were sampled in summer 2018 at three study sites in Dinaric fir-beech forests in the karst area of Slovenia. Three different cutting intensities were performed in 2012: i) no cutting (control), ii) 50% cutting of the stand’s growing stock creating thinned stands, and iii) 100% cutting of the stand’s growing stock creating 0.4 ha canopy gaps. We show that δ13C increased along the gradient of cutting intensity. On average, δ13C values in the tree rings were ∼ 2‰ increased in trees from canopy gaps than from closed control stands. Furthermore, δ13C was higher on south-facing slopes characterized by higher air temperatures and lower relative humidity compared to north-facing slopes of karst sinkholes. Additionally, the results suggest a dependence of δ18O on interannual and cross-site climatic variations, particularly in the case of summer precipitation amount. δ18O also responded to soil depth, with beech individuals exhibiting lower values on deeper soils, presumably characterized by higher soil water availability compared to shallow soils. The results are discussed in the context of future climate change, as many beech-dominated forests on karst terrain in the Dinaric Mountains are particularly affected by climate warming and drying due to prolonged and reoccurring summer droughts, intensified large-scale disturbances, and often shallow soils with low water storage capacity.
Ključne besede: stable carbon isotopes, stable oxygen isotopes, tree cutting, microclimate, drought stress, dinaric fir-beech forests
Objavljeno v DiRROS: 05.04.2023; Ogledov: 879; Prenosov: 261
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154. Bryophyte diversity, composition and functional traits in relation to bedrock and tree species composition in close-to-nature managed forestsLado Kutnar, Janez Kermavnar, Marko S. Sabovljević, 2023, izvirni znanstveni članek Povzetek: Bryophytes respond to a variety of environmental factors, including tree species composition and geological conditions, which are influenced by both natural and anthropogenic factors. Bryophytes growing on a variety of substrates were identified in ICP Forests monitoring plots in a wide range of close-to-nature managed forests, from lowland to high mountain areas in Slovenia. Based on data on tree layer composition (broadleaves vs. conifers) and on bedrock and soil type (calcareous vs. siliceous bedrock), all study plots were classified into five groups representing forest types. Different ordination analyses and statistical tests were used to represent differences between forest types in bryophyte composition, richness and functional traits. Almost 200 bryophyte species were identified in managed forests, with the most common being Hypnum cupressiforme, Brachytheciastrum velutinum and Polytrichum formosum. Bryophyte species composition varied considerably along the tree species composition and edaphic gradients represented by the selected forest types. Bryophyte species richness was significantly higher on calcareous bedrock than on siliceous bedrock. The higher occurrence of rocks on the ground surface may significantly increase the availability of various microhabitats for bryophytes. Bedrock had a significant influence on the functional diversity and composition of bryophytes, while tree species composition had less influence. Bedrock and tree species composition are important drivers of bryophyte species composition and diversity at taxonomic and functional trait levels. The high diversity of bryophyte species in Slovenian forests can also be attributed to close-to-nature and sustainable forest management practices that preserve favourable microclimatic conditions in forest stands and maintain diverse substrates.
Ključne besede: mosses, species richness, functional diversity, site conditions, overstory, sustainable managed forests, European temperate zone
Objavljeno v DiRROS: 05.04.2023; Ogledov: 512; Prenosov: 169
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155. Ecological factors affecting the recent Picea abies decline in Slovenia : the importance of bedrock type and forest naturalnessJanez Kermavnar, Lado Kutnar, Anže Martin Pintar, 2023, izvirni znanstveni članek Povzetek: Norway spruce (Picea abies [L.] Karst.) has been at the centre of controversy for many decades. Recent evidence of its profound disturbance-induced damage and consequent stock depletions across forest landscapes in Europe has reinforced doubts regarding the sustainability and prospects of this tree species in the future. Like many other European countries, Slovenia has experienced significant Norway spruce mortality and a decrease in growing stock primarily as the result of several disturbance agents (bark beetle outbreaks, an ice storm, windthrows). We investigated a countrywide spruce growing stock decline based on data between 2010 and 2018. Particular focus was placed on identifying the main ecological drivers of this decline, namely geological conditions, climatic parameters, soil attributes, topographic factors and forest stand characteristics. The effects of potential predictors on the relative change (%) in spruce volume (m3 ha-1) during the period 2010-2018 were analysed with Generalized Additive Models. Based on a national dataset including forest compartments (n = 6355) with a spruce growing stock decline > 10%, we found mixed support for ecology-based hypotheses. While spruce decline responded to bedrock type as predicted (i.e., greater relative decline in carbonate compared to silicate compartments), higher forest naturalness (preservation of tree species composition) was not associated with a lower decline. Spruce decline was amplified by higher potential evapotranspiration and soil clay content but showed a strong negative relationship with spruce proportion in the year 2010. General trends along the gradients of other selected predictors (stoniness/rockiness and heat load index) were less pronounced. The results suggest that most of these ecological predictors interact with geology and forest naturalness in affecting Norway spruce decline. Our analysis reveals that bedrock type can play an important role due to its mitigating effects. However, forest naturalness is of secondary significance as intensified large-scale forest disturbances likely override its buffering potential.
Ključne besede: Norway Spruce, bark beetle outbreaks, ice storm, soil-geology, relationship, tree species composition, Slovenia
Objavljeno v DiRROS: 05.04.2023; Ogledov: 754; Prenosov: 221
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158. Influence of the calcination duration of ▫$g-C_3N_4/TiO_2$▫ veggie-toast-like photocatalyst on the visible-light triggered photocatalytic oxidation of bisphenol AMatevž Roškarič, Gregor Žerjav, Matjaž Finšgar, Janez Zavašnik, Albin Pintar, 2023, izvirni znanstveni članek Povzetek: Two commercially available TiO2 (hexagonal-like and spherical-like particles) were used to investigate the effect of g-C3N4 “melting” on the photocatalytic properties of g-C3N4/TiO2 composites. Improvement in the contact between the components was observed when they were thermally treated at 350 °C for an extended period of time (between 2 and 72 h) due to the partial melting and phase fusion of g-C3N4. Consequently, the enhanced contact between the phases allows easier injection of photogenerated electrons from the conduction band of g-C3N4 into TiO2, improving charge carrier separation. The prepared composites were tested for bisphenol A degradation under visible-light illumination, which showed that the components that had been calcined for 24 h performed better due to the improved charge carrier separation. Superoxide anionic radicals and photogenerated holes were identified as active species in the photooxidation experiments conducted under visible-light illumination.
Ključne besede: titanium dioxide, photocatalyst, calcination time, photocatalysis under visible-light illumination, water remediation, bisphenol A
Objavljeno v DiRROS: 17.03.2023; Ogledov: 562; Prenosov: 274
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159. Correlations between the catalyst properties and catalytic activity of Au on ▫$ZrO_2-CeO_2$▫ in the hydrogenation of ▫$CO_2$▫Hue-Tong Vu, Matjaž Finšgar, Janez Zavašnik, Nataša Novak Tušar, Albin Pintar, 2023, izvirni znanstveni članek Ključne besede: ▫$CO_2$▫ utilization, gold, mixed oxides, amorphous ▫$ZrO_2$▫, methanol synthesis
Objavljeno v DiRROS: 16.03.2023; Ogledov: 464; Prenosov: 302
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160. Are ecological niche optimum and width of forest plant species related to their functional traits?Janez Kermavnar, Lado Kutnar, Aleksander Marinšek, Valerija Babij, 2023, izvirni znanstveni članek Povzetek: The ecological niche is one of the central concepts in plant ecology. Understanding which biological traits influence plant niches remains limited, preventing large-scale generalizations. Using a representative pool of 94 herb-layer species frequently occurring in the Slovenian forest vegetation types and an extensive suite of 28 plant functional traits, we tested whether traits serve as predictors for the optimum and width of plant species ecological niche. Niche optimum (mean) and niche width (standard deviation) of each species were derived from community-level ecological indicator values for six environmental gradients, i.e., light, temperature, continentality, moisture, soil reaction and nutrients. We investigated relationships between niche parameters and functional traits through a random forest analysis to account for relatively high trait correlations. Our results suggest that niche optimum and width of forest plant species are related to their functional traits. The two niche parameters were best explained by similar set of traits; however, the relative importance of traits differed substantially. Traits associated with disturbances (frequency and severity), plant dispersal (seed mass, dispersal syndrome), leaf economics spectrum (specific leaf area) and life strategy (CSR scores) showed the highest overall significance in predicting niche optimum and width. Functional traits were, on average, better predictors for niche optimum (average variance explained across all six environmental factors: 20.2%) than for niche width (average variance explained: 7.7%). Intraspecific trait variability, not considered in this study, likely plays an important role in case of niche width. The analyses suggest that, while not all traits impact niche parameters to the same degree, it is crucial to consider traits representing different ecological dimensions and revealing leading patterns of trait coordination. We recommend that the relative importance of traits for species niche parameters should be tested on a larger spatial scale using broader pool of forest understory plants across Europe.
Ključne besede: ecological gradients, Ellenberg indicator values, Slovenian forest types, trait-environment relationship, understory plants
Objavljeno v DiRROS: 09.03.2023; Ogledov: 498; Prenosov: 284
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