Jurij Diaci

University of Ljubljana · Biotechnical Faculty

Studies of old-growth forests are becoming increasingly important for the improvement of silviculture and for understanding environmental changes. However, in Europe such forests are rare, fragmented and influenced by millennia of human activity. Comparative studies of old-growth forests across Europe are needed to improve knowledge on how direct a...

Mixed mountain forests composed of Picea abies, Abies alba and Fagus sylvatica represent one of the most important alpine ecosystems with respect to economics, environmental effects and social functions. However, many stands are characterised by even-aged forest structure and altered tree species composition, making them more prone to disturbances...

There is increasing interest across Europe in adopting forest management strategies, which promote species and structural diversity through the use of irregular silvicultural systems, an approach often described as continuous cover forestry (CCF). However, there is little information about the proportion of CCF practised across the continent or abo...

In the last century, a synchronous beech expansion has been observed for many mixed mountain forests in southeastern Europe. This change is associated with the interaction of various disturbances. We analyzed structural changes in the Pecka old-growth forest in Slovenia during the last century, using several inventories of the tree layer, regenerat...

What is Closer to Nature Forest Management? Closer-to-Nature Forest Management is a new concept proposed in the EU Forest Strategy for 2030, which aims to improve the conservation values and climate resilience of multifunctional, managed forests in Europe. Building on the latest scientific evidence, this report attempts to define the concept based...

Close-to-nature forestry (CNF) has a long tradition in European Alpine forest management, playing a crucial role in ensuring the continuous provision of biodiversity and forest ecosystem services, including protection against natural hazards. However, climate change is causing huge uncertainties about the future applicability of CNF in the Alpine r...

Recent observations of tree regeneration failures following large and severe disturbances , particularly under warm and dry conditions, have raised concerns about the resilience of forest ecosystems and their recovery dynamics in the face of climate change. We investigated the recovery of temperate forests in Europe after large and severe disturban...

Purpose of Review Forests support most global terrestrial biodiversity and contribute to the livelihood of billions of people, but these and other benefits are in jeopardy due to global change. This leads to questions, such as how to address the challenges of global change in forest management, given the lack of knowledge and deep uncertainty about...

The frequency of large-scale insect outbreaks is expected to increase with climate change, and the European spruce bark beetle (Ips typographus) is a major forest pest in Europe that has caused more extensive and widespread outbreaks in recent years. It is therefore important to evaluate forest management strategies for controlling bark beetle popu...

Silver fir (Abies alba Mill.) is a key species in the mixed mountain forests of the Dinaric Mountain range, where is typically co-occurs with European beech (Fagus sylvatica L.) and a number of other less dominant species, including Norway spruce (Picea abies). In these forests silver fir is an ecologically and economically important species provid...

Large and severe disturbances may erode the resilience of temperate forest ecosystems and alter their recovery dynamics, especially under global change. We investigated mid-term recovery in mixed mountain forests in Slovenia after three independent severe windstorms in 2008 created large disturbed patches. Across a network of 102 permanent plots an...

The Municipality of Radlje ob Dravi, surrounded by the forested hills of the Pohorje and Kozjak massifs, has an extraordinary heritage of sustainable forest management, which is not surprising given its geographical position. In order to broaden and deepen knowledge of close-to-nature and multifunctional management, whose foundations had been laid...

The Pahernik Foundation advocates close-to-nature forest management that eschews clearcutting. By encouraging young people to study forestry and supporting research, it contributes to the spread and development of close-to-nature management. The foundation’s core activities are the close-to-nature management of the Pahernik forest estate, which als...

Gojenje gozdov je znanost o usmerjanju razvoja gozdov za njihovo ohranitev in izpolnjevanje potreb družbe. Slovensko gojenje gozdov temelji na posnemanju naravnih procesov in ukrepih, prilagojenih lokalnim sestojnim in rastišcnim razmeram. Prvi del ucbenika zato predstavlja gozdove in gojenje gozdov v prostoru in casu, drugi del ekološke dejavnike,...

Rationalization and optimization of work is becoming increasingly important in the European forestry sector. In this study a tool for modeling three different precommercial thinning approaches in young beech mountain stands was developed based on several field studies. The simulation examines three primary types of precommercial thinning: selective...

In the last few decades, an increasing number and intensity of bark beetle outbreaks have plagued the forests of Europe and North America. Bark beetle management is directly related to forest owner characteristics, although this relationship is not well understood. The purpose of the study was to investigate the influence of forest owner characteri...

Management of Norway spruce monocultures in Europe is becoming increasingly difficult due to frequent natural disturbances. Their transformation could be especially challenging if several disturbances interact. In 2003 a spruce bark beetle outbreak damaged large tracts of spruce bottomland successional forest in southeast Slovenia where overabundan...

Pure black alder stands are specific and require adapted silvicultural models. To determine the best intensity of selective thinning in such stands, research plots were established in Polanski Log in 1967. Three thinning intensities were selected: control, moderate and high. These stands are presently in a mature phase. diameter at breast height wa...

Since the mid-19th century, Pinus nigra plantations have played a key role in the restoration of degraded European landscapes. Nowadays, these plantations are aging and prone to natural disturbances, insect infestations, and diseases. For their successful gradual conversion, knowledge of optimal gap spatiotemporal dynamics is crucial. We studied he...

Ungulates affect the development of forest ecosystems in different ways. The most negative impact is a result of a long-term intense overbrowsing of regeneration. The aim of this study was to determine the effect of habitat characteristics and topography on browsing damage to regeneration in Dinaric beech-fir forests. The average damage rate across...

Historical management practices could have a strong effect on the current status of forests and therefore affect the potential for outbreaks of forest pests. We tested whether forest management history and forest tending of Norway spruce affects the potential for bark beetle outbreaks after large disturbances. We also assessed the effect of the pro...

The aim of the research was to study the characteristics and pathways of the successional development of shrubs and tree species on abandoned agricultural land in the Haloze region. Forests and abandoned lands have been increasing in this region for several decades. Thus, we studied the trends of this increase. We compared the species composition o...

Varovalni gozdovi imajo pomembno vlogo pri zmanjševanju učinka različnih naravnih nevarnosti. Kljub povečevanju potreb po varovalni in zaščitni funkcij zaradi staranja gozdov in povečanega tveganja zaradi naravnih motenj ostaja aktivno upravljanje na nizki ravni. Proučili smo učinkovitost varovalnih gozdov za zaščito pred drobirskimi tokovi na seve...

Silvicultural practices are generally developed to meet societal objectives given the constraints of the site. This simple premise is a foundation of modern silviculture. However, silviculture may vary for other reasons related to cultural factors. This paper reviews the differences in silviculture in the twelve countries that comprise southeastern...

The knowledge about the impact of selection silviculture on deadwood components is fairly scarce. This study compared two Dinaric old-growth forests (OGFs) with adjacent managed forests (MFs) in which the single-tree selection system has been applied for a century. The comparisons were made in terms of the current amounts of coarse woody debris (CW...

We studied regeneration dynamics in forests disturbed by three different windthrow events in 2008 in Slovenia to assess the success of natural regeneration vs planting and subsequent silvicultural treatments. Fifty-three plots with planted saplings of Norway spruce and sycamore maple and 50 plots with dominant naturally regenerated saplings were se...

Forest managers are often required to restore forest stands following natural disturbances, a situation that may become more common and more challenging under global change. In parts of Central Europe, particularly in mountain regions dominated by mixed temperate forests, the use of relatively low intensity, uneven-aged silviculture is a common man...

Forest managers are often required to restore forest stands following natural disturbances, a situation that may become more common and more challenging under global change. In parts of Central Europe, particularly in mountain regions dominated by mixed temperate forests, the use of relatively low intensity, uneven-aged silviculture is a common man...

A comparative study of young European beech, silver fir and Norway spruce in the Slovenian mixed forest stands was made at four locations, exposed to the rapid canopy disintegration after the severe ice storm in 2014. Nitrogen amount (N tot), Leaf mass per area (LMA), maximal Assimilation response to light (A max) and Quantum yield (U) were measure...

Quantitative descriptions of natural disturbance regimes are lacking for temperate forest regions in Europe, primarily because a long history of intensive land-use has been the overriding driver of forest structure and composition across the region. The following contribution is the first attempt to comprehensively describe the natural disturbance...

Količina, oblika in časovna razporeditev padavin so izrednega pomena za gozdne ekosisteme, saj pomembno vplivajo na njihovo preskrbo z vodo. Hkrati so gozdovi pomembni z vidika prestrezanja padavin in zadrževanja vode v tleh, s čimer prispevajo k uravnavanju količine vodnih virov v porečju. Natančnejše poznavanje poraz-delitve padavin v gozdnih eko...

In recent years there has been growing interest in the silviculture of uneven-aged forests because of their resilience and stability in an increasingly changing environment. However, some studies have indicated that strict adherence to selection systems results in the homogenization of forest structure. We studied the composition and structure of f...

The practice of salvage logging dead and damaged timber following large high severity disturbances has raised much controversy, partly because of the negative ecological effects that such practices have on forest ecosystems. Many of the studies on salvage logging effects, however, have been done on sites damaged by large, severe disturbances. Less...

The research deals with the effects of forest tending on stand structure and composition on abandoned agricultural lands and possibilities of directing succession development of these stands. This attempt to evaluate the tending ran five vegetation seasons and was divided into three parts. In the first part we checked the initial condition and perf...

Protection forests play an important role in mitigating the influence of natural hazards. Despite the growing need for protective functions due to aging forests and increased risk of natural disturbances, active forest management has become increasingly uncommon across the Alps. Active management of protection forests can be facilitated by state su...

In southeast Europe, silvicultural measures for improving forest protective effects against rockfall are often based on unsystematic observation and experience. We compared formalised expert assessment of forest protective effects and silvicultural decision-making with an approach supported by modelling (Rockyfor3D, Rockfor.NET, shadow angle method...

Izvle�ek V prispevku obravnavamo rezultate prou�evanja naravnega pomlajevanja smrekovih nasadov na rastiš�u predalpskega jelovo-bukovega gozda (Homogyne silvestris-Fagetum) na Krašici (Nazarsko obmo�je) v obdobju 1993 -1998. V poskusu smo zajeli vpliv rastiš�, velikosti in starosti sestojnih vrzeli ter ograj na uspešnost naravnega pomlajevanja smre...

In Europe the area of forested land is increasing, largely due to forest development on abandoned agricultural lands. We compared the structure and composition of woody species in young stands undergoing secondary succession and within gaps of late-successional (LS) forest in Haloze (Slovenia) to derive management options. In a subset of plots in s...

Understanding how forests respond to multiple disturbances is becoming increasingly important under global change. We examined the simultaneous influence of canopy decline and deer browsing on regeneration in an old-growth reserve and surrounding managed forest dominated by Fagus sylvatica L. and Abies alba Mill. in Slovenia. We quantified both dis...

Key messageNatural regeneration of beech, maple and fir was investigated in relation to irradiance, ground vegetation and soil features. Seedling establishment may be favoured by creating small and irregular gaps and by successive extension of gaps along the sun-exposed gap edge.ContextTo successfully manage natural regeneration, it is important to...

Regression of conifers in European mixed old-growth mountain forests has been observed for a long period and studied from different aspects. Old-growth (OG) forests in Bosnia and Herzegovina (BiH) have not experienced heavy air pollution and chronic overbrowsing that have affected many other European OG forests, while climatic and anthropogenic dis...

Regression of conifers in European mixed old-growth mountain forests has been observed for a long period and studied from different aspects. Old-growth (OG) forests in Bosnia and Herzegovina (BiH) have not experienced heavy air pollution and chronic overbrowsing that have affected many other European OG forests, while climatic and anthropogenic dis...

Much of the ecological literature on salvage logging suggests that the negative effects of salvaging on various ecosystem properties and functions are likely to outweigh any economic gains. Most of this work has been carried out following large scale, stand replacing disturbances where all timber is salvaged over large areas. However, in mixed temp...

Over recent decades farmland abandonment has affected large areas of the landscape. To better predict the changes associated with this process, we developed a secondary succession model based on Ellenberg indicator values describing the ecological niche of a tree along environmental gradients. These values are compared with local ecological factors...

Na Oddelku za gozdarstvo in obnovljive gozdne vire BF organiziramo strokovno delavnico »Zelena delovna mesta za gozdarje«. Kot odziv na naglo poslabšanje ekonomskih in socialnih razmer ter zaradi nadaljevanja degradacije okolja so v Evropi začeli v zadnjih letih poudarjati pomen trajnostnega ali krožnega gospodarstva. Trajnostno gospodarstvo temel...

Gap regeneration in a European beech (Fagus sylvatica L.) forest reserve was analyzed in relation to within-gap resource heterogeneity and ground vegetation competition. The study was carried out in two one-hectare permanent research plots (PRP) which included five smaller research plots (RP) encompassing two large gaps (500-700 m(2)), two small ga...

Our study focused on the functional aspects of plant species and vegetation at the transition from larch (Larix decidua Mill.) forest to mountain pine (Pinus mugo Turra) stands on the alpine treeline ecotone. With increasing elevation, living conditions grow harsher, which is reflected in the plant species and functional trait composition of plant...

Forest fires in Slovenian alpine environment are rare and only little is known about the secondary succession after forest fires under these conditions. In 1950, fire destroyed a forest area of 82 ha above Mozirje, which is since known as the Mozirska Požganija forest reserve. The potential forest may be classified as an altimontane beech forest. H...

Silver fir (Abies alba Mill.) is regarded as a typical climax species susceptible to environmental change. We analyzed a protected silver fir stand growing in an unusual combination of conditions: The stand is in secondary succession and is located at low elevation on limestone substrate. Stand history was revealed by an old military map and stand...

Climatic changes affect minor resistance and vitality of the forest, incidence of natural disturbances increases. In this research we compared efficiency of natural and artificial restoration of forests affected by natural disturbances; the stress was laid on structure and growth of seedlings, impact of ground vegetation, and importance of seed tre...

Due to a long history of intensive forest exploitation, few European beech (Fagus sylvatica L.) old-growth forests have been preserved in Europe. We studied two beech forest reserves in southern Slovenia. We examined the structural characteristics of the two forest reserves based on data from sample plots and complete inventory obtained from four p...

Canopy gap recruitment in beech (Fagus sylvatica L.) old-growth forests is influenced by the interplay of the canopy gap disturbance regime, site factors, and stand history. Persistent seedling and sapling banks of beech and other shade tolerant species often play a major role in canopy gap closure. To gain more insight into interactions between me...

Old-growth forest reserves in Slovenia: the past, present, and future Slovenia has a small number of old-growth forest remnants, as well as many forest reserves approaching old-growth conditions. In this paper, we describe some of the basic characteristics of these old-growth remnants and the history of their protection in Slovenia. We then trace t...

The single-tree selection system is an important option for management of Norway spruce (Picea abies (L.) Karst.) and silver fir (Abies alba Mill.) forests because it provides continuous cover, requires low investments for tending, and promotes natural regeneration as well as high stand resistance and elasticity. It is often regarded as a very cons...

Methods based on the principle of hemispherical canopy projection, including hemispherical pho-tography (digital and film), sensors like LAI 2000 (zenith cutoff anle 74,1°) and stable horizontoscope, repre-sent less accurate, yet significantly less expensive and time-consuming techniques for radiation measure-ments compared to long-term measurement...

We studied the immediate effects of two successive storms in 1983 and 2004 in an old-growth Fagus sylvatica L. – Abies alba Mill. forest in the Dinaric Alps, southeastern Slovenia. In the 1983 and 2004 storms the density and basal area of wind-killed trees were 27.4·ha–1 and 5.98 m2·ha–1 and 11.2·ha–1and 4.02 m2·ha–1, respectively. In both storm ev...

Studies of old-growth forests are becoming increasingly important for the improvement of silviculture and for understanding environmental changes. However, in Europe such forests are rare, fragmented and influenced by millennia of human activity. Comparative studies of old-growth forests across Europe are needed to improve knowledge on how direct a...