1. Post-harvest forest herb layer demography : general patterns are driven by pre-disturbance conditionsJanez Kermavnar, Klemen Eler, Aleksander Marinšek, Lado Kutnar, 2021, izvirni znanstveni članek Povzetek: Timber harvesting constitutes extensive anthropogenic disturbance in temperate forests, producing a broad range of ecological impacts that most often enhance the demographic processes of vegetation. This study monitored post-harvest herb layer demography over a 6-year period in mesic Dinaric fir-beech forests (Slovenia), a vascular plant diversity hotspot among European forests. Three experimental harvesting intensities, i.e. full harvest (FH), partial harvest (PH) and a control treatment (NH), were each applied over a circular area of 4000 m2 and replicated three times at each of three study sites. Vegetation sampling was conducted before harvesting (in 2012), and two (2014) and six (2018) years following it, in a 400 m2 circular plot positioned in the centre of each treatment area. We focused on identifying general demographic patterns and evaluating the effects of various pre-disturbance abiotic and biotic predictors on compositional responses to disturbance. Two years after harvest (2012-2014), compositional shifts were larger than those in the next 4-year period (2014-2018), confirming the general theoretical prediction that species turnover rate decreases along a successional gradient. The degree of compositional shifts in gaps (FH) and thinned stands (PH) was affected by local abiotic factors (geomorphology of karst sinkholes) and community attributes, such as pre-harvest species richness. Our results indicate that compositional stability is positively associated with pre-disturbance species richness. Over the whole study period, increases in plot-level species richness (alpha diversity) and overall enrichment of the species pool (gamma diversity) were accompanied by compositional convergence, i.e. a decline in floristic dissimilarity (beta diversity) between and within study sites. However, the observed tendency towards homogenization was rather weak and would have been even more pronounced if the demographic type of persistent resident species had not shown a high degree of resistance, thus leaving a strong imprint on post-harvest vegetation development by preserving the forest characteristics of the herb layer community.
Ključne besede: forest succession, demographic types, community assembly, pre-disturbance factors, floristic convergence, fir-beech forests
Objavljeno v DiRROS: 22.07.2022; Ogledov: 201; Prenosov: 138
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2. Carbon flux and environmental parameters data from an eddy covariance tower in a mid-succession ecosystem developed on abandoned karst grassland in Slovenia (2012-2019)Koffi Dodji Noumonvi, Klemen Eler, Dominik Vodnik, Primož Simončič, Mitja Ferlan, 2021, zaključena znanstvena zbirka raziskovalnih podatkov Povzetek: This data set was used to estimate carbon fluxes by comparing eddy covariance tower (Long = 13.916701, Lat = 45.543491) measurements with vegetation indices based estimates.
Ključne besede: eddy covariance, GPP, NEE, empirical model, LUE model, vegetation photosynthesis model, vegetation indices
Objavljeno v DiRROS: 21.02.2022; Ogledov: 390; Prenosov: 291
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3. Root growth dynamics of three beech (Fagus sylvatica L.) provenancesPeter Železnik, Marjana Westergren, Gregor Božič, Klemen Eler, Marko Bajc, Heljä-Sisko Helmisaari, Aniko Horvath, Hojka Kraigher, 2015, objavljeni povzetek znanstvenega prispevka na konferenci Objavljeno v DiRROS: 03.11.2021; Ogledov: 475; Prenosov: 319
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7. Climatic regulation of leaf and cambial phenology in Quercus pubescens : their interlinkage and impact on xylem and phloem conduitsJožica Gričar, Jernej Jevšenak, Polona Hafner, Peter Prislan, Mitja Ferlan, Martina Lavrič, Dominik Vodnik, Klemen Eler, 2022, izvirni znanstveni članek Povzetek: Increased frequency and severity of stressful events affects the growth patterns and functioning of trees which adjust their phenology to given conditions. Here, we analysed environmental effects (temperature, precipitation, VPD and SWC) on the timing of leaf phenology, seasonal stem radial growth patterns, and xylem and phloem anatomy of Quercus pubescens in the sub-Mediterranean in the period 2014%2019, when various adverse weather events occurred, i.e. spring drought in 2015, summer fire in 2016 and summer drought in 2017. Results showed that the timings of leaf and cambium phenology do not occur simultaneously in Q. pubescens, reflecting different environmental and internal constraints. Although year-to-year variability in the timings of leaf and cambial phenology exists, their chronological sequence is fairly fixed. Different effects of weather conditions on different stages of leaf development in spring were observed. Common climatic drivers (i.e., negative effect of hot and dry summers and a positive effect of increasing moisture availability in winter and summer) were found to affect the widths of xylem and phloem increments with more pronounced effect on late formed parts. A legacy effect of the timing of leaf and cambial phenology of the previous growing season on the timing of phenology of the following spring was confirmed. Rarely available phloem data permitted a comprehensive insight into the interlinkage of the timing of cambium and leaf phenology and adjustment strategies of vascular tissues in Mediterranean pubescent oak to various environmental constraints, including frequent extreme events (drought, fire). Our results suggest that predicted changes in autumn/winter and spring climatic conditions for this area could affect the timings of leaf and stem cambial phenology of Q. pubescens in the coming years, which would affect stem xylem and phloem structure and hydraulic properties, and ultimately its performance.
Ključne besede: pubescent oak, leaf development, radial growth, initial earlywood vessel, sieve tube, anatomy, cambial cell production, extreme weather events
Objavljeno v DiRROS: 06.09.2021; Ogledov: 615; Prenosov: 105
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8. Transition dates from earlywood to latewood and early phloem to late phloem in Norway SpruceJožica Gričar, Katarina Čufar, Klemen Eler, Vladimir Gryc, Hanuš Vavrčík, Martin De Luis, Peter Prislan, 2021, izvirni znanstveni članek Povzetek: Climate change will affect radial growth patterns of trees, which will result in different forest productivity, wood properties, and timber quality. While many studies have been published on xylem phenology and anatomy lately, little is known about the phenology of earlywood and latewood formation, also in relation to cambial phenology. Even less information is available for phloem. Here, we examined year-to-year variability of the transition dates from earlywood to latewood and from early phloem to late phloem in Norway spruce (Picea abies) from three temperate sites, two in Slovenia and one in the Czech Republic. Data on xylem and phloem formation were collected during 2009-2011. Sensitivity analysis was performed to determine the specific contribution of growth rate and duration on wood and phloem production, separately for early and late formed parts. We found significant differences in the transition date from earlywood to latewood between the selected sites, but not between growth seasons in trees from the same site. It occurred in the first week of July at PAN and MEN and more than two weeks later at RAJ. The duration of earlywood formation was longer than that of latewood formation; from 31.4 days at PAN to 61.3 days at RAJ. In phloem, we found differences in transition date from early phloem to late phloem also between the analysed growth seasons; from 2.5 weeks at PAN to 4 weeks at RAJ Compared to the transition from earlywood to latewood the transition from early phloem to late phloem occurred 25-64 days earlier. There was no significant relationship between the onset of cambial cell production and the transition dates. The findings are important to better understand the inter-annual variability of these phenological events in spruce from three contrasting temperate sites, and how it is reflected in xylem and phloem anatomy.
Ključne besede: Picea abies, xylem formation, phloem formation, cambium, tracheid, sieve cell, conifer, temperate environment
Objavljeno v DiRROS: 22.03.2021; Ogledov: 751; Prenosov: 627
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9. Effects of various cutting treatments and topographic factors on microclimatic conditions in Dinaric fir-beech forestsJanez Kermavnar, Mitja Ferlan, Aleksander Marinšek, Klemen Eler, Andrej Kobler, Lado Kutnar, 2020, izvirni znanstveni članek Povzetek: Forest microclimate is strongly affected by local topography and management activities, as these directly alter overstory structure. In the present work we analysed the dependence of observed patterns of spatio-temporal microclimatic variations on topographic, canopy- and management-related factors. A forestry experiment was conducted in managed fir-beech forests in the Dinaric Mountains (Slovenia), which are characterized by rugged karstic terrain with numerous sinkholes. In 2012, cutting treatments representing a range in the intensity of overstory removal were performed: uncut controls (CON), 50% cut of stand growing stock (intermediate management intensity % IMI) and 100% cut (high management intensity % HMI) creating 0.4 ha canopy gaps. Fine-scale variation in aspect and slope and its effects on microclimate was assessed by comparing central, south-facing and north-facing within-sinkhole positions. We measured microclimatic variables (air temperature % T, relative humidity % RH) 0.5 m above the ground over three consecutive post-treatment growing seasons. Microclimatic variables showed an increase (T and vapour pressure deficit % VPD) or decrease (RH) with management intensity. Daily Tmax and VPDmax in HMI treatment were up to 5.9°C (on average 3.5°C) and up to 1.4 kPa (on average 0.6 kPa) higher than those in CON treatment, respectively, whereas daily RHmin was up to 22.7 (on average 13.0) percentage points lower. Regarding intra-seasonal patterns, microclimatic differences between treatments were largest during the summer. South-facing plots in the HMI treatment overall exhibited the most extreme conditions, i.e. the highest Tmax and lowest RHmin. Differences in microclimate between treatments were strongly modulated by canopy cover. The results also suggest that overstory removal increases topography-mediated variation in microclimate, as evidenced by significant differences in T, RH and VPD along the fine-scale topographic gradient within the created canopy gaps.
Ključne besede: tree cutting, air temperature, relative humidity, vapour pressure deficit, karst topography, canopy cover
Objavljeno v DiRROS: 08.10.2020; Ogledov: 983; Prenosov: 345
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10. Elevated ozone prevents acquisition of available nitrogen due to smaller root surface area in poplarTanja Mrak, Klemen Eler, Ovidiu Badea, Yasutomo Hoshika, Elisa Carrari, Elena Paoletti, Hojka Kraigher, 2020, izvirni znanstveni članek Povzetek: Aims Poplars are ecologically and economically important tree genus, sensitive to ozone (O3). This study aimed to investigate modifying effects of elevated O3 on poplar root response to nutrient addition. Methods In pot experiment, young trees of an O3-sensitive Oxford poplar clone (Populus maximoviczii Henry x berolinensis Dippel) growing in soil with three levels of P (0, 40 and 80 kg ha-1) and two levels of N (0 and 80 kg ha-1) were exposed to three levels of O3 (ambient - AA, 1.5 x AA, 2.0 x AA) at a free air exposure facility. After one growing season, root biomass, fine root (<2 mm) nutrient concentrations and ratios, and fine root morphology were assessed. Results Nitrogen addition resulted in an up to +100.5% increase in coarse and fine root biomass under AA, and only up to +46.3% increase under 2.0 x AA. Elevated O3 and P addition had a positive effect, while N had a negative effect on P concentrations in fine roots. Nitrogen limitation for root growth expressed as a N:P ratio was more pronounced at elevated O3. Nitrogen addition increased root surface area per soil volume by +78.3% at AA and only by +9.9% at 2.0 x AA. Conclusions Smaller root surface area per soil volume at elevated O3 prevented acquisition of available N, rendering N fertilization of young poplar plantations in such conditions economically and environmentally questionable.
Ključne besede: fine roots, nitrogen, phosphorus, Populusmaximoviczii x berolinensis, ozone, Poplar
Objavljeno v DiRROS: 16.06.2020; Ogledov: 1479; Prenosov: 779
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