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Iskalni niz: "avtor" (Klemen Eler) .

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11.
Effects of various cutting treatments and topographic factors on microclimatic conditions in Dinaric fir-beech forests
Janez 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: 1274; Prenosov: 524
.pdf Celotno besedilo (1,59 MB)
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12.
Elevated ozone prevents acquisition of available nitrogen due to smaller root surface area in poplar
Tanja 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: 1806; Prenosov: 983
.pdf Celotno besedilo (775,68 KB)
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13.
Post-fire effects on development of leaves and secondary vascular tissues in Quercus pubescens
Jožica Gričar, Polona Hafner, Martina Lavrič, Mitja Ferlan, Nives Ogrinc, Bor Krajnc, Klemen Eler, Dominik Vodnik, 2020, izvirni znanstveni članek

Povzetek: An increased frequency of fire events on the Slovenian Karst is in line with future climate-change scenarios for drought-prone environments worldwide. It is therefore of the utmost importance to better understand tree-fire-climate interactions for predicting the impact of changing environment on tree functioning. To this purpose, we studied the post-fire effects on leaf development, leaf carbon isotope composition (%13C), radial growth patterns and the xylem and phloem anatomy in undamaged (H-trees) and fire-damaged trees (F-trees) of Q. pubescens with good re-sprouting ability in spring 2017, the growing season after a rangeland fire in August 2016. We found that the fully developed canopy of F-trees reached only half of the LAI values measured in H-trees. Throughout the season, F-trees were characterised by higher water potential and stomatal conductivity and achieved higher photosynthetic rates compared to unburnt H-trees. The foliage of F-trees had more negative %13C values than those of H-trees. This reflects that F-trees less frequently meet stomatal limitations due to reduced transpirational area and more favourable leaf-to-root ratio. In addition, the growth of leaves in F-trees relied more on the recent photosynthates than on reserves due to the fire disturbed starch accumulation in the previous season. Cambial production stopped 3 weeks later in F-trees, resulting in 60% and 22% wider xylem and phloem increments, respectively. A novel approach by including phloem anatomy in the analyses revealed that fire caused changes in conduit dimensions in the early phloem but not in the earlywood. However, premature formation of the tyloses in the earlywood vessels of the youngest two xylem increments in F-trees implies that xylem hydraulic integrity was also affected by heat. Analyses of secondary tissues showed that although xylem and phloem tissues are interlinked changes in their transport systems due to heat damage are not necessarily coordinated.
Ključne besede: pubescent oak, cambium, radial growth, xylem, phloem, anatomy, sub-Mediterranean
Objavljeno v DiRROS: 19.03.2020; Ogledov: 2378; Prenosov: 1270
.pdf Celotno besedilo (732,75 KB)
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Mikroklimatske razmere v sestojih in vrzelih dinarskih jelovobukovih gozdov Slovenije z vidika podnebnih sprememb
Janez Kermavnar, Mitja Ferlan, Aleksander Marinšek, Klemen Eler, Andrej Kobler, Lado Kutnar, 2019, izvirni znanstveni članek

Povzetek: Dinarski jelovo-bukovi gozdovi so eden glavnih gozdnih vegetacijskih tipov v Sloveniji, v katerih so se v zadnjem obdobju zaradi naravnih ujm spremenile ekološke razmere. Namen raziskave je bila analiza izbranih spremenljivk mikroklime (temperatura zraka, relativna zračna vlaga) v strnjenih sestojih, v presvetljenih sestojih in v sestojnih vrzelih na treh raziskovalnih območjih (Trnovski gozd, Snežnik, Kočevski rog). Za strnjene sestoje je bila značilna visoka stopnja zastiranja tal s krošnjami dreves ( ~ 95 %). Sestojne vrzeli so nastale s posekom vseh dreves na krožni površini 0,4 ha, v presvetljenih sestojih pa je bila posekana približno polovica lesne zaloge gozdnega sestoja. Ukrepi so bili izvedeni leta 2012, meritve meteoroloških spremenljivk pa smo opravili prvo (2013) in drugo (2014) leto po sečnji. Primerjali smo, kako se mikroklimatske razmere v sestojih in vrzelih spreminjajo v vegetacijski sezoni (maj-oktober) in kakšne so razlike med dvema meteorološko razmeroma različnima poletjema v letih 2013 (več vročinskih valov, poletna suša) in 2014 (nestanovitno vreme z relativno veliko količino padavin). Izmerjene najvišje dnevne temperature zraka (Tmax) so bile izrazito višje v vrzelih kot v sestoju, v povprečju za 3,6 °C; najnižja relativna zračna vlaga (RVmin) pa je bila nižja, v povprečju za 15,0 odstotnih točk. Razlike v obeh spremenljivkah med sestoji in vrzelmi so bile največje v poletnih mesecih (junij-avgust) leta 2013 (Tmax: 4,9 °C; RVmin: -19,7 odstotnih točk), ki je bilo razmeroma vroče in sušno. Na podlagi meritev meteoroloških spremenljivk in zastora drevesnih krošenj (podatki LiDARskega snemanja) v presvetljenih sestojih smo ugotovili statistično značilno negativno linearno povezavo med zastorom drevesnih krošenj in Tmax ter pozitivno povezavo med zastorom krošenj in vrednostmi RVmin. Rezultate analiz smo prikazali v luči potencialnih vplivov podnebnih sprememb, katerim so dinarski jelovo-bukovi gozdovi zaradi kombinacije neugodnih dejavnikov npr. zmanjšana mehanska in biološka stabilnost sestojev zaradi velikopovršinskih motenj, poletne suše, vodoprepusten kraški teren ter pogosto plitva tla z majhno sposobnostjo zadrževanja vode - še posebej izpostavljeni.
Ključne besede: dinarski jelovo-bukovi gozdovi, temperatura zraka, relativna zračna vlaga, sestojne vrzeli, zastor krošenj dreves, podnebne spremembe, Slovenija
Objavljeno v DiRROS: 20.12.2019; Ogledov: 2536; Prenosov: 771
.pdf Celotno besedilo (388,92 KB)

15.
Evaluating short-term impacts of forest management and microsite conditions on understory vegetation in temperate fir-beech forests : floristic, ecological, and trait-based perspective
Janez Kermavnar, Aleksander Marinšek, Klemen Eler, Lado Kutnar, 2019, izvirni znanstveni članek

Povzetek: Forest understory vegetation is largely influenced by disturbances and given local abiotic conditions. Our research focuses on the early response of understory vegetation to various forest management intensities in Dinaric fir-beech forests in Slovenia: (i) control, (ii) 50% cut of stand growing stock, and (iii) 100% cut of stand growing stock. Apart from identifying overstory removal effects, we were interested in fine-scale variation of understory vegetation and environmental determinants of its species composition. Vegetation was sampled within 27 karst sinkholes, which represent a dominant landform in studied forests. Within each sinkhole, five sampling plots, varying in slope aspect (centre, north, east, south, west), were established (135 in total), where pre-treatment (in 2012) and post-treatment (in 2014) floristic surveys were conducted. The sampled understory species were characterized in terms of Ellenberg's indicator values (EIVs) and plant functional traits (plant height, seed mass, specific leaf area, leaf dry matter content). Diversity metrics (species richness, total cover, Shannon index) increased in plots where the silvicultural measures were applied. Tree species richness also increased in 100% cutting. A redundancy analysis revealed that species composition was related to environmental variables, which are directly influenced by management interventions (overstory canopy cover, microclimate maximum daily temperature, soil properties thickness of organic soil layer) as well as by topographic factors (slope inclination and surface rockiness). EIVs for light were significantly affected by treatment intensity, whereas soil-related EIVs (moisture, reaction, nutrients) depended more on the within-sinkhole position. Canopy gaps, compared with uncut control plots, hosted a higher number of colonizing species with a higher plant height and smaller seeds, while leaf traits did not show a clear response. We found a negative correlation between pre-treatment species (functional) richness and post-treatment shifts in floristic (functional) composition. Plots with higher richness exhibited smaller changes compared with species-poor communities. Incorporating different perspectives, the results of this study offer valuable insights into patterns of understory vegetation response to forest management in fir-beech forests.
Ključne besede: canopy gap, microsite environment, Ellenberg indicator values, plant functional traits, compositional resistance, karst topography, fir-beech forest
Objavljeno v DiRROS: 06.12.2019; Ogledov: 2443; Prenosov: 1522
.pdf Celotno besedilo (1,95 MB)
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On the use of R programming language in the analyses of spatial data
Milan Kobal, Andrej Ceglar, Klemen Eler, Barbara Medved Cvikl, Luka Honzak, Primož Simončič, David Hladnik, 2013, izvirni znanstveni članek

Povzetek: R is a powerful and increasingly popular programming language with strong graphical and presentation features and large expanŽdability. Although primarily intended for statistical computing, R has paved its way to the field of GIS through the development of specialized extension packages. It offers a wide range of functions at all GIS levels: data acquisition, data manipulation, graphical reŽpresentation and quantitative analysis. The paper presents R as an open source alternative to the existing commercial GIS software. It proves especially well when advanced quantitative methods on spatial data are needed (e.g. spatial modelling). We demonstrate R capabilities through spatial analysis of forest area in Snežnik (South Slovenia), where the possibilities of data import, conversion and export into various GIS formats and possibilities of geostatistics, spatial modelling and spatial visualization are demonstrated.
Objavljeno v DiRROS: 12.07.2017; Ogledov: 5074; Prenosov: 2677
.pdf Celotno besedilo (2,43 MB)

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