71. Vpliv prostoživečih velikih rastlinojedov na travniške ekosistemeSamar Al Sayegh-Petkovšek, Boštjan Pokorny, Dejan Firm, Klemen Jerina, 2015, review article Abstract: Velike prostoživeče rastlinojede uvrščamo med ključne vrste kopenskih ekosistemov, saj neposredno in posredno vplivajo na številne druge skupine organizmov in na zgradbo ter delovanje celotnih ekosistemov. Veliki rastlinojedi s prehranjevanjem, teptanjem, uriniranjem in iztrebljanjem prerazporejajo hranila, vplivajo na zbitje, prezračenost in erozijo tal, razširjajo rastlinska semena ter pogosto povečujejo raznovrstnost travniških ekosistemov, še zlasti v produktivnih travniških ekosistemih, na primer v zmernem podnebju Evrope. Številčnost in prostorska razširjenost večine vrst prostoživečih prežvekovalcev narašča v večjem delu Evrope, vključno s Slovenijo. Na posameznih, prostorsko omejenih lokacijah se povečujejo težave (npr. izgube travniške krme na travinju) predvsem zaradi paše jelenjadi (Cervus elaphus L.). Deli Notranjske in Kočevske se hitro zaraščajo, hkrati so to območja z največjimi gostotami jelenjadi, kar povečuje njene pritiske na preostale travnike in pašnike, zlasti tiste, ki so intenzivneje gnojeni. Slednje se zlasti med oškodovanci (kmetovalci) pogosto poudarja kot pomembna škoda zaradi izgube v pridelavi travniške krme. Vendar lahko parkljarji vplivajo na gospodarsko donosnost travinja tudi posredno, in sicer z oblikovanjem vrstne sestave travišč ter spreminjanjem produktivnosti tal. Za celostno upravljanje je treba poznati tudi njihove neposredne in posredne ekološke vplive in pomene. V članku smo zato pripravili pregled domačih in tujih raziskav neposrednih in posrednih vplivov prostoživečih velikih rastlinojedov na travniške ekosisteme.
Keywords: prostoživeči rastlinojedi parkljarji, jelenjad, paša, škode na traviščih, ekološki vplivi
Published in DiRROS: 12.07.2017; Views: 4919; Downloads: 2340
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73. On the use of R programming language in the analyses of spatial dataMilan Kobal, Andrej Ceglar, Klemen Eler, Barbara Medved Cvikl, Luka Honzak, Primož Simončič, David Hladnik, 2013, original scientific article Abstract: 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.
Published in DiRROS: 12.07.2017; Views: 5284; Downloads: 2733
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74. Zanesljivost makroskopskega (okularnega) ocenjevanja starosti jelenjadi (Cervus elaphus L.) v Sloveniji : preizkus s štetjem letnih prirastnih plasti zobnega cementaBoštjan Pokorny, Klemen Jerina, Ida Jelenko Turinek, 2012, original scientific article Keywords: navadni jelen, Cervus elaphus L., ocenjevanje starosti, obraba zob, spodnja čeljustnica, plasti zobnega cementa
Published in DiRROS: 12.07.2017; Views: 4993; Downloads: 2063
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75. Vpliv podnebnih sprememb na pričakovano prostorsko prerazporeditev tipov gozdne vegetacijeLado Kutnar, Andrej Kobler, Klemen Bergant, 2009, original scientific article Abstract: V raziskavi smo simulirali prostorsko prerazporeditev tipov gozdne vegetacije v Sloveniji, do katere bi lahko prišlo ob pričakovanih podnebnih spremembah. Potencialne prostorske spremembe gozdne vegetacije so bile analizirane v GIS okolju s pomočjo empiričnega modela, ki napoveduje prostorsko razporeditev gozdne vegetacije v odvisnosti od podnebnih in drugih parametrov. Rezultati simulacij na osnovi treh podnebnih scenarijev kažejo, da se bo vzorec razporeditve gozdne vegetacije menjal pod vplivom podnebnih sprememb. Po napovedih bi lahko do leta 2070 prišlo do sprememb vegetacijskega tipa na več kot 75 % vseh gozdnih površin. Danes prevladujoči, pretežno bukovi gozdovi bi lahko bili v spremenjenih okoljskih razmerah močno prizadeti. Model napovedujepadec deleža prevladujočih mezofilnih bukovih gozdov s sedanjih 57 %na samo 3 % po pesimističnem scenariju in do 29 % po optimističnem scenariju.V toplejšem podnebju, ki ga predvidevajo vsi trije scenariji, bi se močno razširili različni termofilni gozdovi.
Published in DiRROS: 12.07.2017; Views: 4606; Downloads: 2069
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76. How the estimates of home range size and composition are affected by diurnal, nocturnal and 24-hour sampling methods: example of the red deer (Cervus elaphus) in SloveniaKlemen Jerina, 2009, original scientific article Abstract: Most of the previous research on the mammals' home range (HR) is based on diurnal sampling, while the results are often implicitly considered as representative for an entire 24-h period. However, there is a growing body of research on populations, whose habitat selection changes circadianly, which leads to the hypothesis that HR patterns may vary at different periods of the day. This study used 24-h data from 15 red deer equipped with GPS collars to explore differences in the size and composition of their HRs, estimated on diurnal, nocturnal and 24-h samplings. The differences in composition were shown on the forest/non-forest variable. We established that nocturnal, and inparticular the 24-h HRs, largely overlapped with the diurnal HRs (64% and 76%, respectively) and that parts of the HRs that are used exclusively nocturnally are contiguous or adjacent to diurnal HRs. The differences in HR sizes were significant only between diurnal and 24-h HRs. However, the HR composition varied substantially: the average proportion of non-forest areas was 15% in diurnal, 26% in 24-h and 31% in nocturnal HRs. This study demonstrated that with diurnal sampling it is impossible to assess accurately the size and composition of 24-h HRs of red deer in Slovenia. There are several indices that the same is true of several other populations/species. It is therefore important to be aware that HR patterns estimated on the basis of diurnal sampling may be incomplete or even wrong if generalised across the 24-h period.
Published in DiRROS: 12.07.2017; Views: 4534; Downloads: 1954
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77. Učinkovitost odstrela volkov (Canis lupus) kot ukrepa za zmanjševanje škode na domačih živalihMiha Krofel, Rok Černe, Klemen Jerina, 2011, original scientific article Abstract: Škoda, povzročena na domačih živalih, je ena glavnih težav pri ohranitvenem upravljanju z volkom (Canis lupus). Škodo se pogosto poskuša zmanjšati z odstrelom volkov. V pričujoči raziskavi smo analizirali učinke legalnega odstrela volkov na obseg škode v Sloveniji ter pripravili pregled podobnih raziskav iz tujine. V letih 1995-2009 je bilo legalno odstreljenih 51 volkov in zabeleženih 2221 primerov napadov volkov na domače živali. S statističnimi analizami nismo ugotovili nobenih vplivov odstrela volkov na višino škode. Učinkov odstrela ni bilo zaslediti niti tedaj, ko smo med seboj primerjali najbolj ekstremna leta. Naši rezultati se ujemajo z izsledki tujih raziskav, ki prav tako opozarjajo, da (v nasprotju s splošnim prepričanjem!) trajnostni lov volkov ni učinkovit ukrep za zmanjšanje škode. Odstrel postane učinkovit šele, če z njim iztrebimo celo populacijo ali odstranimo večino volkov iz večjega območja. Ker je škoda na drobnici v Sloveniji resen problem in ker odstrel volkov očitno nima želenega učinka, priporočamo, da se v prihodnje napori in sredstva osredotočijo v bolj učinkovite ukrepe.
Keywords: volk, odstrel, lov, škoda, ovce
Published in DiRROS: 12.07.2017; Views: 4905; Downloads: 1991
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78. Red deer (Cervus elaphus) bark stripping on spruce with regard to spatial distribution of supplemental feeding placesKlemen Jerina, Mihec Dajčman, Miha Adamič, 2008, original scientific article Abstract: Forest damages caused by red deer and some other large herbivore species occasionally feeding on tree bark, are a grave ecological and economic problem in many parts of the world. Winter supplemental feeding is commonly used to mitigate the problem, but its effects are poorly known. This study, carried out at Pohorje (Slovenia) and including over 2,300 trees, used binary logistic regression to analyse the effects of supplemental feeding and many other factors on the probability of bark stripping on spruce. The probability of bark stripping depends on distance from the forest edge, density, age and tree species diversity of stands, slope and aspect of terrain, and red deer density; contrary to expectations, it is not related to distance from feeding places. As much as 35% of spruce trees were damaged. The damage was the highest in younger, denser pure spruce stands, whose favourable protective and microclimatic conditions (thinner snow cover, higher effective temperatures) make them a preferred winter habitat for red deer. They contain,however, little other food but bark. To prevent / diminish bark stripping we propose a stronger thinning of such stands. Supplemental feeding may reduce damage only in exceptional cases, when animals are lured and concentrated in less sensitive areas, but in general we advise against the use of this measure due to its other negative effects.
Keywords: red deer, Cervus elaphus, bark stripping, Norway spruce, Picea abies, forest damages, supplemental feeding, Slovenia, environmental factors
Published in DiRROS: 12.07.2017; Views: 4477; Downloads: 1980
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79. The effects of habitat structure on red deer (Cervus elaphus) body massKlemen Jerina, 2007, original scientific article Abstract: In most mammalian species, body mass is one of the key factors affecting an individual's fitness. It is therefore important to know the causes of its variability. The present paper analyses the influences of habitat structure and other environmental factors on body mass in red deer. The research is based on data sets concerning 3,920 culled red deer from the entire Slovenia, which are geo-referenced within a kilometer spatial accuracy, and on 28 spatially explicit raster layers of population density, habitat structure variables (e.g. topography, land use, forest structure, roads) and other environmental variables (e.g. air temperature, precipitation, supplementary feeding). After controlling for sex and age of the individual and its date of culling, body weight significantly differs between population areas, most likely as a result of genotype differences and genotype impact on the phenotype, and is also negatively dependent upon population density and the percentage of conifers and positively dependent upon annual mean air temperature and forest/meadow edge density. The stated environmental factors probably influence the achieved energy balance and, therefore, the body mass of red deer by conditioning the quantity and quality of food and energy expenditure of deer.
Keywords: red deer, body weight, habitat, evironmental factors, population density, forest edge, conifer, temperature, Slovenia
Published in DiRROS: 12.07.2017; Views: 4598; Downloads: 2026
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80. Vplivi okoljskih dejavnikov na prostorsko razporeditev divjega prašiča (Sus scrofa l.) v SlovenijiKlemen Jerina, 2006, original scientific article Abstract: Številčnost in območje razširjenosti divjega prašiča (Sus scrofa L.) sta se v Sloveniji in drugih evropskih državah v zadnjih desetletjih občutno povečala; posledično so narasle tudi škode, ki jih povzroča v kmetijstvu. V raziskavi smo preučili, kateri okoljski dejavniki ključno vplivajo na prostorsko razporeditev divjega prašiča, in za Slovenijo ugotovili njegovo sedanje in potencialno območje razširjenosti. Raziskava temelji na velikem vzorcu (N = 5.977) georeferenciranih lokacij odvzema prašiča iz vse Slovenije in GIS-podatkovnih plasteh (25 okoljskih spremenljivk). Analize kažejo, da so gostote divjega prašiča največje v območjih: (a) z večjo razpoložljivosti energijsko bogate hrane (odrasli sestoji listavcev, krmišča) in dostopnostjo kritja (kmetijske površine blizu gozda, sukcesijske površine); (b) kjer so temperature visoke, zime mile, z malo snega (verjetnost rabe narašča s temperaturo in upada s količino padavin). Njegova prostorska razporeditev je odvisna tudi od gozdnatosti in stopnje fragmentacije gozda. Zdaj poseljuje 55 % Slovenije, njegov potencialni habitat pa obsega 67 % države. Razširjenost inštevilčnost divjega prašiča se bosta zato verjetno še povečevala, zlasti če se bodo nadaljevali sedanji trendi okoljskih sprememb (naraščanje temperature,povečevanje gozdnatosti, izginjanje iglavcev).
Keywords: divji prašič, prostorska razporeditev, okoljski dejavniki, fragmentacija, dopolnilno krmljenje, model habitata, logistična regresija
Published in DiRROS: 12.07.2017; Views: 4740; Downloads: 2002
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