Robert Brus

• PhD
• Professor (Full) at University of Ljubljana

Information on public attitudes towards the use of transgenic trees in forest plantations is important in the decision-making process and policy implementation for safe tree development, particularly at the EU level. In Europe, the use of transgenic forest trees is very limited and therefore such information is completely lacking. To address this i...

We examined leaf and mature seed cone variation of Juniperus oxycedrus L. subsp. oxycedrus in 12 natural populations across the species range in the Balkan Peninsula. We measured 10 morphological traits from a minimum of 100 leaves in each of 190 individuals, and two morphological traits from 30–50 seed cones in each of 94 females. High phenotypic...

Background and Purpose: It is widely accepted that south-European peninsulas were major refugial areas from where European beech, Fagus sylvatica L., spread to the rest of Europe in the Holocene. The aim of this paper is to review and evaluate all the available data and present different types of evidence, some of them new or overlooked until now,...

Sessile oak ( Quercus petraea (Matt.) Liebl.) is widely distributed across most of Europe particularly the hills and lower mountain ranges, so is considered “the oak of the mountains”. This species grows on a wide variety of soils and at altitudes ranging from sea level to 2200 m, especially in Atlantic and sub-Mediterranean climates, and it is sen...

To enhance our understanding of forest carbon sequestration, climate change mitigation and drought impact on forest ecosystems, the availability of high-resolution annual forest growth maps based on tree-ring width (TRW) would provide a significant advancement to the field. Site-specific characteristics, which can be approximated by high-resolution...

Abstract: Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), one of the most commercially important tree species in western North America and one of the most valuable timber trees worldwide, was introduced to Europe in 1827. It became a major species for aforestation in Western Europe after WWII, currently grows in 35 countries on over 0.83 millio...

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), one of the most commercially important tree species in western North America and one of the most valuable timber trees worldwide, was introduced to Europe in 1827. It became a major species for afforestation in Western Europe after WWII, currently grows in 35 countries on over 0.83 million ha and...

Key message The relationships between growth rates of examined provenances in the sub-Mediterranean change between juvenile and adult growth phase, while wood density is approximately similar in all four examined provenances. Abstract Tree rings, wood density and the climate–growth relationship of four Douglas-fir provenances were analysed separat...

Wood in outdoor applications is subject to various decomposition factors. Wood degradation can be prevented by construction details, biocide protection of wood, wood modification or selection of naturally durable species. Unfortunately, most species in Europe do not have naturally durable wood. Imported tree species represent a new pool from which...

Non-native forest tree species have been introduced in Europe since the 16th century, but only in the second half of the 20th century the significance of the seed source origin for their economic use was recognized, resulting in the establishment of numerous provenance trials at a national, regional, European and International level, as those led b...

Six broadleaf tree species (Celtis australis L. – Mediterranean hackberry, Quercus petraea (Matt.) Liebl. – sessile oak, Fagus sylvatica L. – European beech, Prunus avium L. – wild cherry, Juglans regia L. – Persian walnut and Acer pseudoplatanus L. – sycamore maple) were planted in 2012 in a trial in the Slovenian Karst on two sites differing in p...

The aim of the study was to review the legislation and legal framework for the cultivation of non-native tree species in Slovenian forests. In the EU, several legal instruments are relevant for the introduction, use and management of non-native tree species, e.g. the Council Directive on the marketing of forest reproductive material, the Habitats D...

This study focuses on the morphological and genetic characteristics of European crab apple (Malus sylvestris (L.) Mill.) and the occurrence of hybrids in its populations. We analyzed a total of 107 putative European crab apple trees in Slovenia: 92 from nine natural populations, five from a seed stand and 10 from a stand of unnatural origin. We als...

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is a non-native conifer from western North America that was introduced into European forests at the end of the 19th century. Plantations of Douglas-fir in Europe have shown good performance, quality, and resilience to exacerbating climatic conditions. However, all these qualities strongly depend on...

The sycamore maple with a fiddleback figure (FB) and straight grained (C) was sampled to study structural properties, wood density and dimensional stability, in relation to elastomechanical and acoustic properties of wood. Test specimens with cross section of 30 by 30 mm were conditioned in a normal-, dry-(20 °C / 35 RH) and humid-climate (20 °C /...

Black walnut (Juglans nigra L.) is a light-demanding, competition-intolerant, and tall forest tree species, introduced in Europe from North America at the beginning of the seventeenth century. It has an important economic role in Europe for producing wood and fruits, in agroforestry systems, as an ornamental tree for parks and avenues, for rehabili...

Black locust (Robinia pseudoacacia L.), a species native to the eastern North America, was introduced to Europe probably in 1601 and currently extends over 2.3 × 106 ha. It has become naturalized in all sub-Mediterranean and temperate regions rivaling Populus spp. as the second most planted broadleaved tree species worldwide after Eucalyptus spp. T...

Ecology and management of northern red oak (Quercus rubra L. syn. Q. borealis F. Michx.) in Europe: a review Northern red oak (Quercus rubra L. syn. Q. borealis F. Michx.) is a valuable broadleaved tree species originating from the eastern half of the USA and Canada. It was introduced to Europe in 1691 and currently covers over 350 000 ha, being fo...

Europe has a history rich in examples of successful and problematic introductions of trees with a native origin outside of Europe (non-native trees, NNT). Many international legal frameworks such as treaties and conventions and also the European Union have responded to the global concern about potential negative impacts of NNT that may become invas...

Black locust (Robinia pseudoacacia L.), a species native to the eastern North America, was introducedto Europe probably in 1601 and currently extends over2.3 × 10 6 ha. It has become naturalized in all sub-Mediterranean and temperate regions rivaling Populus spp. as the second most planted broadleaved tree species worldwide afterEucalyptus spp. Thi...

We analyzed possibilities for detecting tree species in the framework of Monitoring of Forests and Forest Ecosystems (MGGE) with the highlight on minority and non-native tree species as well as possibilities for detecting the differences in the tree species diversity between each ecological regions. Detecting minority and non-native tree species co...

In the context of Europe, the southern peninsulas including the Balkans are considered hotspots of diversity. They preserved substantial parts of tree species and genera occurring in Europe during the Tertiary, as the effects of the Quaternary glaciations on species richness were not as severe here as in more northerly regions. The Balkans also har...

Serbian spruce (Picea omorika (Pančić) Purk.) is an endemic tree species from the Balkan Peninsula. The species also thrives in Slovenia and would be an interesting minority alternative to Norway spruce (Picea abies (L.) Karst.) on some sites. This study was carried out in a Serbian spruce plantation below Počivalnik hill, between Unec and Postojna...

The management of non-native tree species in European forests has a long history, but the information on the current number and geographic distribution of these species in European forests is incomplete and scattered across various datasets. This study aims to perform an inventory of the most frequent non-native tree species growing in European for...

Hazelnut (Corylus avellana) is cultivated on 118 ha and ranks eighth in Slovenian fruit growing production, representing 2.8% of the total area of fruit plantations in the country. However, decline of some of the trees appeared in 2012 in two plantations located in eastern Slovenia. Together these orchards cover 5 ha, with around 1600 trees planted...

The chapter gives an overview of the development of forestry in Slovenia in the light of managing and conserving forest genetic resources. Special attention is given to the description of the legislative framework, the international collaboration, the extent and functioning of the Slovenian forest gene bank, forest genetic monitoring as the necessa...

Larger number of wild cherry candidate plus trees in the entire area of Slovenia were identified and recorded. Detailed seven-scale evaluation of their vitality, stem straightness, crown size, constriction, cylindrical trunk growth, trunk warping, branch diameter, branching angle and forking resulted in the selection of 107 trees possessing the mos...

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...

Non-native tree species are widely used in forest plantations and agroforestry systems worldwide for their often-high productivity and performance compared to native trees. In addition, they have been and are introduced and used for multiple reasons, such as gardening, protective functions, arboreta, erosion control and for increasing the forest ar...

The aim of our research was to study the impact of various environmental factors on the resin production of pines in the Slovenian Karst. Five plots were established % three in Pinus nigra (Arnold) stands and two in Pinus sylvestris (L.) stands. On each plot, the 19-20 most vigorous dominant or codominant trees with a minimum diameter at breast hei...

Celtis australis (L.), the European Nettle Tree, is a tree typical of the Mediterranean and warmer sub Mediterranean forests, where it occurs individually or in small groups. The species is adapted to drought, it is resistant to diseases, pests and pollution and produces high quality wood. In order to promote and increase the proportion of Celtis a...

This research studied the only two sites where the Swiss stone pine (Pinus cembra L.) is considered to be native to Slovenia: one below Mount Krnes and one near Mount Bela Peč, both of which form part of the Smrekovec massif. The exact locations of individual trees were determined using a GPS device. The trees were measured and inspected in terms o...

Field elm (Ulmus minor Mill.) and wych elm (U. glabra Huds.) notably contribute to the biological diversity in lowland and montane forest ecosystems in Slovenia where natural presence of these species in forests constitute 0.1% of wood stock. In southwestern Slovenia (Beka, Kastelec, and Gabrovica) from May to October 2016, field elm trees exhibite...

GozdV 75 (2017) 1 3 Znanstvena razprava GDK 412+181.1:176.1Ailanthus altissima (Mill.) Swingle(497.4)(045)=163.6 Nekateri ukrepi za omejevanje širjenja visokega pajesena (Ailanthus altissima (Mill.) Swingle) in smernice za gozdnogojitveno ukrepanje ob vdoru potencialno invazivnih tujerodnih drevesnih vrst v ohranjene gozdove v Sloveniji Control tre...

Daphne blagayana is a small decumbent bush from the family Thymelaeaceae with a fragmented distribution range, comprising the Balkan Peninsula and the southern Romanian Carpathians. Due to its rarity it is protected by national legislation in almost all countries within its range. The aim of this work was to assess the plastid diversity of Daphne b...

Tree of heaven (Ailanthus altissima (Mill.) Swingle) is one of the most significant non-native invasive tree species in Slovenia. We studied how it regenerates and spreads into the natural environment in the Goriška region. We confirmed its diverse reproductive capability, since in the new environment it successfully reproduces both generatively an...

Swiss stone pine (Pinus cembra L.) is a mountain tree species of the pine genus. Small and fragmented populations are found in the Alps and Carpathians with Swiss stone pine forming pure stands and mixed stands with larch and spruce. Spotted nutcracker (Nucifraga caryocatactes) has an important role in its seed dispersal. The timber is appreciated...

Information on public awareness and acceptance issues regarding the use of Genetically Modified (GM) trees in forestry is lacking, although such information is available for GM organisms in agriculture. This is mainly due to the fact that in Europe there is no authorization for commercial planting of GM forest trees. To address this issue and withi...

The eastern distribution limit of Spiraea decumbens s. str. is in Breginjski Kot (northwestern Slovenia), where we recorded 49 localities of this eastern-Alpine endemic plant species. We determined two new localities in a new quadrant (9746/4) on riparian rocks of the Nadiža River under Mt. Mija at Kozja Peč, which is currently the southeasternmost...

The conversion of old black pine plantations into ecologically more stable broadleaf forests is an important goal in many Mediterranean countries. Six experimental plots split between more and less productive sites were established in the sub-Mediterranean climate zone of south-western Slovenia in an area of mostly pure black pine stands. In Novemb...

The wavy grain of wood expressed in fiddleback figure usually enhances its commercial value. The goal of this study was to analyse fiddleback figure and other log characteristics in sycamore maple (Acer pseudoplatanus L.) and their contribution to the price of the timber. We studied sycamore maple logs at the annual auction of the highest quality w...

European crab apple (Malus sylvestris (L.) Mill.) is indigenous and relatively poorly studied tree species in Slovenia. Through detailed morphometric analysis, we examined 97 trees from 9 populations. Based on the most appropriate morphological characters for identification of European crab apple, hairiness of leaves and diameter of fruits, only 44...

Microsatellite markers were used to describe the genetic structure of a natural wild cherry (Prunus avium L.) stand in Slovenia. Based on eight analyzed loci, only 67 different multilocus genotypes (MLGs) were identified among 217 trees, indicating a significant amount of clonal reproduction in the stand. Lowspatial genetic structure (SGS) was obse...

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...

Marginal tree populations are believed to be more differentiated and host less variation than central tree populations. The aim of this study was to perform a detailed morphometric study of J. oxycedrus L. subsp. oxycedrus in northern marginal populations in order to establish its phenotypic variation and geographical differentiation and to examine...

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...

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...

Conversion of the aging black pine planta tions into ecologically more stable broadleaf forests is an important goal in many Mediterranean countries as well as in the sub-Mediterranean part of Slovenia. Six experimental plots, split between the more and the less productive site, were established near Divača in southwestern Slovenia in an area of mo...

The introduction of non-native tree species to the territory of present-day Slovenia has not been well documented. The first documented introduction of a considerable number of species took place at the end of the 18th and the beginning of the 19th century. The estimated average time lag between the first known introduction of a particular species...

We conducted a survey of wood and performed dendrochronological dating of beams from the external walls of the old Ban’s House in the village of Artiče near Brežice. The logs were made of different wood species, with different oaks among them, i.e. sessile oak (Quercus petraea), pedunculate oak (Quercus robur) and Turkey oak (Quercus cerris), as we...

Gynodioecious Daphne laureola L. is one of six species of the genus Daphne L. native to Slovenia. The main goals of this research were to determine the distribution of Daphne laureola in the Bohor area, the sexual structure of populations and its correlation with site conditions, and whether morphological differences exist between females and herma...

Eleven mixed populations of Juniperus oxycedrus L. and Juniperus communis L. were inventoried for the presence of parasitic woody species Arceuthobium oxycedri (DC.) M. Bieb. infections. Both J. oxycedrus and A. oxycedri are rare and distributed in marginal populations in Slove-nia. To our knowledge, this is the first detailed research on the host...

Assumption that forest reproductive material is better adapted to local conditions is the basis of current forest policy that promotes the use of local material. Genetic diversity and structure of two approved seed stands and three non-approved stands of Fraxinus excelsior L. were analysed with nuclear microsatellites to get genetically based suppo...

Microsatellite markers were used to describe the genetic variability of four seed stands of wild cherry (Prunus avium L.). One hundred and thirty one individuals were genotyped at ten nuclear microsatellite loci. Total genetic diversity was high (H E = 0.704), while differences between stands were small but significant (F ST = 0.053, G9 ST = 0.234)...

A monograph deals with trees and shrubs growing along the entire eastern Adriatic coast from northern Italy (Gorizia, Monfalcone and Trieste region) through Slovenia and Croatia (Istria, Kvarner, Dalmatia) to Montenegro and Albania. In the book 126 species are introduced with extended monographs and over 200 additional species are introduced in sho...

In the book 187 native and non-native tree species that thrive in Slovenia are presented in separate monographs, and further 200 species are presented with short descriptions. For each tree species detailed morphological description, flowering information, distribution, ecophysiological features, usability, exceptional trees and systematic affiliat...

Fraxinus angustifolia Vahl is a species native in the north-western Balkans, where it has a divided range. Most of its range is located in flood-prone riparian sites in the Pannonian plain but the species is also found on humid sites along some rivers in the Submediterranean region. We analysed morphologic variation within and between five populati...

In most European countries, the service tree (Sorbus domestica L.) is a rare and threatened species and its conservation has been recognised as a priority. The aim of this study was to asses its morphologic variation in the western and central part of the Balkan Peninsula and in southern Central Europe. Three populations were analysed: one in Serbi...

Daphne blagayana Freyer (fam. Thymelaeaceae), a small evergreen bush, is a tertiary relict with a fragmented distribution range in the Balkan Peninsula. The species has been protected in Slovenia (as well as in some other countries) since 1898 and is classified as vulnerable in the Red Data List of Threatened Vascular Plants in Slovenia. It grows o...

Background and Purpose: Conservation efforts across Europe and a substantial lack of information regarding the present status of black poplar (Populus nigra L.) in Slovenia led us to conduct this research. The objectives were to determine the presence of preserved native black poplar in Slovenia, to evaluate the variation within and between two sel...

In Slovenia, as well as in others parts of Europe, the share of abandoned agricultural land overgrown by forest has been increasing every year. This article deals with this process of succession in Haloze, in the northeastern part of Slovenia. The main aim of this research was to find out how much of the abandoned agricultural land on the studied a...

Seeds carry in their genes the potential of newly developing trees. In the process of natural regeneration natural processes exclude the seed with unfavourable genotype, while with artificial regeneration this responsibility is in the hands of foresters. Today, traditional seed quality tests can be complemented with molecular ones as genetic divers...

Genetic variation of 57 Southeast-European populations of Abies alba was studied by means of maternally inherited mitochondrial nad5-4 gene marker and isozyme gene markers in 18 nuclear loci.Geographic distribution of mtDNA haplotypes revealed 2 zones where different Postglacial re-colonization routes have met. The zone in the Ukraininan Carpathian...

The paper reviews the research dealing with the presence of silver fir (Abies alba Mill.) within modern-day Slovenian territory in the Pleistocene and Holocene. The data on paleobotanical remains (Tertiary fossil remains, pollen, macroscopic plant remains) on Paleolithic sites and on genetic properties of the present silver fir populations are pres...

This article introduces a determination key for ornamental cultivars of European beech. The key allows successful identification of 76 different cultivars. Data about cultivars that can be found in public places and specialized collections in Slovenia are also included. We recorded 16 different cultivars. Their list corresponds well to the list of...

There are three ash species native to Slovenia: manna ash (Fraxinus ornus L.), narrow-leaved ash (Fraxinus angustifolia Vahl) and common ash (Fraxinus excelsior L.). Based only on morphological traits it is difficult to distinguish between closely related common and narrow-leaved ash, particularly on sites where the two species are sympatric. Leaf...

Oskoruša (Sorbus domestica L.) je vrsta drveća iz porodice Rosaceae zastupljena u kserotermnim šumama, a u uzgoju je kao voćkarica. Rasprostranjena je u južnoj i srednjoj Europi, sjevernoj Africi, na Krimu i u Maloj Aziji. U većini europskih zemalja vrlo je rijetka i ugrožena vrsta koja zaslužuje zaštitu i čije je očuvanje prepoznato kao prioritet....

The objective of this research was to study the distribution, share and influence of black locust (Robinia pseudoacacia L.) on the forest stands in northeast Slovenia. The analyses of data from Slovenian forest service data base showed that in forest management region of Murska Sobota highest black locust shares in growing stock are reached by the...

Root systems and types of ectomycorrhizae (ECM) were analysed on three 7-year-old beech seedlings (Fagus sylvatica L.) of three provenances (Val di Sella, Idrija, Nizbor) from an international beech provenance trial and on a naturally regenerated 5-year-old beech seedling from the same site (Kamenski vrh by Novo mesto). All short roots were mycorrh...

The Blagay Daphne (Daphne blagayana Freyer) was one of the first legally protected plants in Slovenia. As the species occurs mostly in forest habitats, we attempted to determine its present condition and the extent to which protection principles are considered and practiced in the Ljubljana forest-management region, where the plant was discovered....

Thirty silver fir populations originating from the putative suture zones of the postglacial recolonization (Slovenia, Bosnia and Hercegovina, Ukraine) were studied using a mitochondrial nad5-4 gene marker. The geographical distribution of mtDNA haplotypes in the Ukrainian Carpathians and their northern foothills indicates a very recent meeting of m...

The study investigates the genetic variation and genetic differentiation of the beech (Fagus sylvatica L.) in Central and Southeastern Europe. On the basis of isozyme analysis, 56 indigenous beech populations were examined. Polymorphysm was revealed in all 12 isozyme loci; 43 different alleles were found alltogether. The beech populations form two...

Tree of heaven (Ailanthus altissima (Mill.) Swingle) is one of the most important invasive tree species across Europe. In this paper its distribution, invasiveness, ecological properties, morphology and eradication possibilities are discussed. Distribution map of thee of heaven in Slovenia is elaborated. SLOVENIAN LANGUAGE.

Genetic differentiation of 57 beech populations originating from a wide geographical space from the foothills of the Eastern Alps over the Balkan peninsula was investigated employing isozyme markers. Pooled datasets of European beech populations originating from four adjacent regions and Eastern beech populations originating from Thrace and Western...

The study investigates the genetic variability, genetic diversity and genetic diflerentiation of the beech (Fagus sylvatica L.) in Slovenia. On the basis of isozyme analysis, 13 indigenous beech populations were examined. Polymorphism was revealed in 11 isozyme loci, 9 loci show polymorphism in all treated populations. The trend of slight north-sou...

The paper deals with the distribution and morphological, ecological and taxonomical characteristics of terebinth (Pistacia terebinthus L.) in Slovenia. The distribution map of this species is presented. In addition to known localities three new locations in the new quadrants of the Central European flora mapping are presented. The species is confir...

The paper introduces one of the tallest European trees, a 61,7 metre tall Norway spruce (Picea abies (L.) Karst.) from the Pohorje, Slovenia. Other exceptionally tall European and Slovenian trees are described. Site conditions in which Sgerm’s spruce is growing are compared to site conditions characteristic for other of the tallest European spruce...

Eighteen European beech (Fagus sylvatica L.) populations, twelve of which are relatively undamaged and six severely damaged, were analyzed. Six populations were young; three of them polluted and three unpolluted. The following twelve isozyme loci were used: GOT-B, IDH-A, LAP-A, MDH-A, MDH-B, MDH-C, MNR, PX-A, PX-B, PGM, PGI-B and SKDH. Significant...

Evergreen oak species Quercus crenata in among rarest tree species in Slovenia. In the past only some trees were found in the vicinity of the Reka river, but three more trees in two new quadrants of the Central European flora mapping were found in Kras recently. IN SLOVENE, WITH ABSTRACT IN ENGLISH.

This paper adresses selected genetic properties of silver fir (Abies alba Mill.) populations in Slovenia. Using analyses of 10 anzyme systems and 16 isozyme loci, genetic structure, genetic diversity and genetic differentiation of 8 Slovene silver fir populations are compared to silver fir populations from other parts of Europe. Hypotheses tested w...

The paper introduces one of the tallest European trees, a 61,7 metre tall Norway spruce (Picea abies (L.) Karst.) from the Pohorje. Other exceptionally tall European and Slovenian trees are described. Site conditions in which Sgerm’s spruce is growing are compared to site conditions characteristic for other of the tallest European spruce trees. IN...

The dendroflora of the Balkan peninsula is in comparison with the dendrofloras of other European regions very rich and diverse. Endemics and relicts, which can be found on the Balkans in a much greater number than anywhere in Europe, greatly contribute to this opulence. Among numerous natural and historical reasons for the present state, morphogene...