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Keywords: navadni jelen, Cervus elaphus L., ocenjevanje starosti, obraba zob, spodnja čeljustnica, plasti zobnega cementa
Published in DiRROS: 12.07.2017; Views: 4856; Downloads: 2032
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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: 4441; Downloads: 1934
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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: 4355; Downloads: 1949
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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: 4584; Downloads: 1970
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Abstract: To understand better the adaptation strategies of intra-annual radial growth in Pinus halepensis and Pinus sylvestris to local environmental conditions, we examined the seasonal rhythm of cambial activity and cell differentiation at tissue and cellular levels. Two contrasting sites differing in temperature and amount of precipitation were selected for each species, one typical for their growth and the other represented border climatic conditions, where the two species coexisted. Mature P. halepensis trees from Mediterranean (Spain) and sub-Mediterranean (Slovenia) sites, and P. sylvestris from sub-Mediterranean (Slovenia) and temperate (Slovenia) sites were selected. Repeated sampling was performed throughout the year and samples were prepared for examination with light and transmission electron microscopes. We hypothesized that cambial rhythm in trees growing at the sub-Mediterranean site where the two species co-exist will be similar as at typical sites for their growth. Cambium in P. halepensis at the Mediterranean site was active throughout the year and was never truly dormant, whereas at the sub-Mediterranean site it appeared to be dormant during the winter months. In contrast, cambium in P. sylvestris was clearly dormant at both sub-Mediterranean and temperate sites, although the dormant period seemed to be significantly longer at the temperate site. Thus, the hypothesis was only partly confirmed. Different cambial and cell differentiation rhythms of the two species at the site where both species co-exist and typical sites for their growth indicate their high but different adaptation strategies in terms of adjustment of radial growth to environmental heterogeneity, crucial for long-term tree performance and survival.
Keywords: Aleppo pine, Pinus halepensis, Scots pine, Pinus sylvestris, cambium, light microscopy, Mediterranean environment, temporate environment, transmission electron microscopy, xylem
Published in DiRROS: 12.07.2017; Views: 3144; Downloads: 1431
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