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 found all over the continent, except the coldest part of Scandinavia. It is a fast-growing and valuable broadleaved tree due to its ecological characteristics, good wood properties and high economic value. Northern red oak prefers deep, loose, moderately humid and acid soils, without compact horizons and of at least moderate fertility. It does not grow well on dry, calcareous soils as well as waterlogged or poorly drained soils. It is either naturally regenerated using a group shelterwood system or planted using seedlings of European provenance, collected in certified seed stands. As northern red oak is light-demanding, its management should be ‘dynamic’ and includes heavy interventions (cleaning–respacing and thinning from above), in order to minimize crown competition between the final crop trees. These should produce large diameter trees for valuable end uses (e.g. veneer, solid furniture, lumber, etc.) within a rotation period generally of 80–100 years. The necessity for pruning (both formative and high) depends on the stand stocking at establishment, the subsequent silvicultural interventions as well as the occurrence of forking. The adaptation potential of northern red oak to predicted climate change, especially drought, seems to be higher than for European native oaks, the importance of the species is expected to increase in the future.

wood, fodder, and a source of honey as well as bio-oil and biomass. It is also important for carbon sequestration, soil stabilization and re-vegetation of landfills, mining areas and wastelands, in biotherapy and landscaping. In Europe, black locust is drought tolerant so grows in areas with annual precipitation as low as 500-550 mm. It tolerates dry, nutrient poor soils but grows best on deep, nutrient-rich, well-drained soils. It is a fast-growing tree and the height, diameter and volume growth peak before the age of 20. It mostly regenerates vegetatively by root suckers under a simple coppice system, which is considered the most cost-effective management system. It also regenerates, but less frequently, by stool sprouts. Its early silviculture in production forests includes release cutting to promote root suckers rather than stool shoots, and cleaning-respacing to remove low-quality stems, reduce the number of shoots per stool, and adjust spacing between root suckers. In addition, early, moderate and frequent thinning as well as limited pruning are carried out focusing on crop trees. The species is regarded as

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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 Serbia, one in Bosnia and Herzegovina and one in Slovenia. In each population 30 trees were selected, and from each tree 30 leaves were collected for morphometric analysis based on nine leaflet morphological traits. Univariate (ANOVA) and multivariate (MANOVA) analysis of variance were used to estimate the variation within-and between populations and a discriminant analysis was performed to examine the structure of the between-population differences. The values of particular morphological traits found in our study did not differ considerably from the values reported elsewhere. The results revealed significant within-and between population variation. Variation within populations was highly significant for all the scored leaf morphological traits, while variation between populations was significant for all the studied traits except for the leaflet length. The discrimination between the three populations was significant. High percentages of correctly classified samples demonstrate good discriminating employability of the analysed leaf morphological traits and indicate differentiation of the analysed populations.

(18)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 issue within the FP0905 European COST Action on the Biosafety of Transgenic Forest Trees a pioneer cross-country pilot survey on public attitudes towards the use of transgenic forest trees was conducted using young population as a focus group. This was decided mainly because this focus group represents the future consumers, policy makers or developers. Specifically, the survey aimed to: i) assess the level of young people's knowledge about transgenic forest trees, ii) identify issues of concern to them regarding the cultivation of transgenic forest trees and iii) explore whether they approve or disapprove of the use of transgenic forest trees in plantations. Purposive sampling was performed and university students of different disciplines were included in the research as sampling subjects. In total, 1868 completed questionnaires from 15 European and nonEuropean countries were analyzed. The young educated people that took part in the survey appeared to approve of the use of transgenic forest trees in plantations and would be willing to buy forest transgenic products. The potential loss of biodiversity due to a risk of gene flow between transgenic and wild trees was seen as the safety issue of most concern when considering the commercial release of transgenic forest trees. However, a serious perceived lack of knowledge about potential benefits and risks of the cultivation of transgenic forest trees was recorded in most of the countries. K-means clustering was implemented on respondents' positive responses to identify potential country patterns. No differences in patterns of public attitude towards the acceptance of the commercial growing of transgenic forest trees were observed between European and non-European countries. Extended research on public attitude issues towards the use of transgenic forest trees is strongly recommended as a basis for policy implementation on safe tree development.

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 invasive in natural ecosystems. It is, however, national and regional legislation in particular that affects current and future management decisions in the forest sector and shapes the landscapes of Europe. We identified all relevant legal instruments regulating NNT, the different legal approaches and the regulatory intensity in 40 European countries (no microstates). Information on hard and effective soft law instruments were collected by means of a targeted questionnaire and consultation of international and national legislation information systems and databases. In total, 335 relevant legal instruments were in place in June/July 2019 to regulate the use of NNT in the investigated 116 geopolitical legal units (countries as well as sub-national regions with their own legislation). Countries and regions were empirically categorized according to ad hoc-defined legislation indicators. These indicators pay respect to the general bans on the introduction of non-native species, the generally allowed and prohibited NNT, approval mechanisms and specific areas or cases where NNT are restricted or prohibited. Our study revealed a very diverse landscape of legal frameworks across Europe, with a large variety of approaches to regulating NNT being pursued and the intensity of restriction ranging from very few restrictions on species choice and plantation surface area to the complete banning of NNT from forests. The main conclusion is that there is a clear need for more co-ordinated, science-based policies both at the local and international levels to enhance the advantages of NNT and mitigate potential negative effects.

Abstract: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 November 2012 they were planted with six native broadleaf species (Celtis australis, Quercus petraea, Fagus sylvatica, Prunus avium, Juglans regia and Acer pseudoplatanus). The test plantations were intended to become small initial nuclei from which the introduced broadleaf species could later spread naturally into the old and partly degraded pine plantations. Seedling condition was assessed one year after planting. Based on their high survival rates after the first growing season, all tested species except F. sylvatica showed promising potential for future conversion of old pine stands in the Slovenian Karst region. However, the results of one growing season only are insufficient to draw firm conclusions. Of all planted species P. avium had the highest survival rate (95%) and was least susceptible to poor field conditions. Without exception, all species showed lower survival rate on the less productive site. Unlike other species, P. avium and J. regia seedlings had considerable height increment, while F. sylvatica had the lowest. From the results we can assume that perhaps old pine stands in the area have already considerably improved soil conditions and thereby enabled the introduction of broadleaves.Additional key words: planting broadleaves, forest conversion, survival rate, height increment, tree vigour