41. Mikroklimatske razmere v sestojih in vrzelih dinarskih jelovobukovih gozdov Slovenije z vidika podnebnih spremembJanez 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: 2584; Prenosov: 784
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42. Evaluating short-term impacts of forest management and microsite conditions on understory vegetation in temperate fir-beech forests : floristic, ecological, and trait-based perspectiveJanez 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: 2491; Prenosov: 1560
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43. Effects of disturbance on understory vegetation across Slovenian forest ecosystemsLado Kutnar, Thomas Andrew Nagel, Janez Kermavnar, 2019, izvirni znanstveni članek Povzetek: The herbaceous understory represents a key component of forest biodiversity across temperate forests of Europe. Here, we quantified changes in the diversity and composition of the forest understory layer in representative Slovenian forest ecosystems between 2004/05 and 2014/15. In total, 60 plots were placed across 10 different managed forest types, ranging from lowland deciduous and mid-altitude mesic mixed forests to mountain conifer forests. This network is part of an international network of sites launched within the ICP Forests Programme aimed to assess the condition of forests in Europe. To examine how disturbance influenced understory dynamics, we estimated the disturbance impacts considering both natural and/or anthropogenic disturbances that cause significant damage to trees and to ground-surface layers, including ground-vegetation layers and upper-soil layers. Species richness across 10 sites (gamma diversity) significantly decreased from 272 to 243 species during the study period, while mean species richness per site did not significantly change. The mean value of site level Shannon diversity indices and evenness significantly increased. The cover of most common plant species increased during the monitoring period. The mean value of disturbance estimates per site increased from 0.8% in 2004/05 (ranging from 0% to 2.5%) to 16.3% in 2014/15 (ranging from 5.0% to 38.8%), which corresponded to a reduction in total vegetation cover, including tree-layer cover. More disturbed sites showed larger temporal changes in species composition compared to less disturbed sites, suggesting that forest disturbances caused understory compositional shifts during the study period. Rather than observing an increase in plant diversity due to disturbance, our results suggest a short-term decrease in species number, likely driven by replacement of more specialized species with common species.
Ključne besede: vegetation dynamics, vascular-plant diversity, understory layer, disturbance, monitoring, temperate forests
Objavljeno v DiRROS: 27.11.2019; Ogledov: 2349; Prenosov: 1433
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44. Invazivna tujerodna rastlinska vrsta kudzu (Pueraria montana var. lobata) je potencialna grožnja za slovenske gozdoveJanez Kermavnar, Lado Kutnar, Aleksander Marinšek, Jana Kus Veenvliet, Maarten De Groot, 2019, strokovni članek Povzetek: Kudzu (Pueraria montana var. lobata) je invazivna tujerodna rastlinska vrsta, za katero v Sloveniji do pred nedavnim ni bilo podatkov o pojavljanju v naravi. Poleti 2018 sta bili v informacijskem sistemu Invazivke (www.invazivke.si) potrjeni prvi najdbi kudzuja pri nas v naravnem okolju. V tej podatkovni bazi se kot podpora za sistem zgodnjega obveščanja in hitrega odzivanja (ZOHO), ki se razvija v sklopu projekta LIFE ARTEMIS, zbirajo podatki o invazivnih tujerodnih vrstah pri nas. Obe nahajališči kudzuja sta v submediteranskem fitogeografskem območju Slovenije, v bližini Strunjana in v Dekanih. Namen članka je predstaviti osnovne značilnosti invazivne rastlinske vrste, ki pri nas ni dobro znana. V prispevku opozarjamo tudi na potencialne negativne vplive, ki bi jih kudzu lahko povzročil z nenadzorovanim širjenjem, predvsem v gozdnem prostoru. Na ravni EU je kudzu zaradi potencialnih škodljivih vplivov na okolje uvrščen med tiste invazivne tujerodne vrste, za katere morajo države članice sprejeti takojšnje stroge ukrepe za odstranitev oziroma preprečitev širjenja. Zgodnje obveščanje in hitro odzivanje v začetnih fazah širjenja sta ključni dejavnosti, ki bistveno pripomoreta k učinkovitemu zmanjševanju negativnih vplivov invazivnih tujerodnih vrst.
Ključne besede: kudzu, Pueraria montana var. lobata, invazivne tujerodne vrste, Invazivke.si, gozdovi, Slovenija
Objavljeno v DiRROS: 20.03.2019; Ogledov: 3288; Prenosov: 936
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