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.

Polycyclism is the ability for a plant to produce several flushes in the same growing season. The rare phenomenon of common oak (Quercus robur L.) summer flowering is proof of complex polycyclism. Common oak summer flowering and the unusual transformation of inflorescences were the starting point for this study of the phenological variability of common oak trees in identical site conditions. This paper presents comparative research of leaf flushing, flowering, and leaf fall phenophases in a common oak with summer flowering and a control tree in which this phenomenon was not observed. Both trees displayed frequent polycyclism (polyphase formation of annual shoots during the growing season), but with different intensities depending on the trees and the years. Compared to the control tree, the tree with summer flowering was characterized by a later onset of leaf-flush phenophase and leaf fall phenophase and a longer retention of the leaves in the crown

Growth and structure of Italian alder (Alnus cordata /Loisel/ Duby) trees were analyzed in a linear plantation established by planting two-year-old seedlings at Fruška Gora (Serbia). The aim of this paper is to point out the growth characteristics and the structure of the Italian alder linear plantation at age 11 and 16 years and contribute to the knowledge of adaptive and productive potential of the species in the available plantation in Serbia. The spacing between the trees was 7 m (200 trees per hectare). The plantation is located on anthropogenically changed pedunculate oak and hornbeam site at 125 m above sea level. On the basis of 35 measured trees at age 11 and 16 years, the top height was 15 and 21 m, and the Lorey’s mean height 13.4 and 19.5 m. The dominant diameter was 32.4 cm at age 11 and 59.4 cm at age 16 years. The mean quadratic diameter was 25.1 and 47 cm.The productivity of the plantation is high. At age 11 years, the basal area was 9.9 m2∙ha−1, and the standing volume 107.2 m3∙ha−1 while at age 16 years, it was 34.7 m2∙ha−1 and 305.1 m3∙ha−1, respectively. In the period from 11 to 16 years of age, the periodic annual increment in diameter was 4.4 cm∙year−1, height 1.22 m∙year−1, and in basal area and volume 4.9 m2∙ha−1·year−1and 39.6 m3·ha−1·year−1, respectively, pointing to fast growth of Italian alder. Despite the limits due to a small sample and the fact that the linear plantation was analyzed, we generalise the ­following conclusion: the measured growth characteristics at age 11 and 16 years of Italian alder trees show that the species can grow fast and could be usable in similar areas.

Извод: У раду се приказује изграђеност очуваних, високих, зрелих, састојина и младих састојина насталих планском обновом или спонтаном разградњом истих у монодоминантним шумама китњака (Quercetum petraeae Čer. et Jov. 1953.), из две субасоцијације, tilietosum и typicum, на подручју Националног парка "Ђердап". Приказ зрелих састојина се заснива на подацима са огледних површина, прикупљаним 1992. године, у периоду који карактерише појава масовног сушења китњака на наведеном подручју, и широм Европе. У састојинама, старим око 150 година у 1992. години, у спрату дрвећа је био заступљен само китњак. Састојине су са потпуним до густим склопом и имају високе износе запремине, а у структури по биолошком положају, квалитету дебла, развијености крошње и степену сушења стабала међу њима нема јаснијих разлика. Приказ младих састојина се заснива на подацима са трајне огледне површине, прикупљаним 2017. године, као и на подацима других аутора. Изграђеност младих састојина указује да је у фази обнове старих састојина потребно планирати различите узгојне мере у различитим субасоцијацијама монодоминантне шуме китњака, да би се очувало учешће китњака у довољној бројности.

The paper presents the occurrence of subspontaneous dispersal of Kentucky coffeetree in the park-forest which is a part of a protected natural area "Topciderski park" in Belgrade. In 1949, three trees of Kentucky coffeetree not older than 85 years were recorded. In 2016, one sexually reproductive tree was recorded in Topcider which is assumed to be one of the three "mother" trees recorded in 1949. The diameter at breast height is 94.6 cm and the height of the tree is 24.1 m. During the past seven decades, the Kentucky coffeetree regenerated successfully from seed and root suckers in the area that was under anthropogenic influence and was left to succession, but the Kentucky coffeetree has not shown invasiveness. In the area of subspontaneous dispersal of Kentucky coffeetree (0.25 ha), all the trees that had diameter at breast height 1.0 cm and more were measured. Fourteen tree and shrub species were identified with a total of 624 trees and Kentucky coffeetree was the most represented species with 326 trees (52.2%). In the subspontaneous regenerated group of Kentucky coffeetree, the diameter at breast height of the thickest tree is 48.2 cm and the highest tree is 25.5 m tall. The diameter structure of Kentucky coffeetree trees shows the declining distribution. Compared to the habitus of "mother" tree, that has a slenderness of 25, the habitus of the dominant and codominant trees in the subspontaneous regenereted group of Kentucky coffeetree is characterized by slenderness of 75-110 that is characteristic of the trees grown in the stand closure.

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 variation was found, but no geographical structure or cline across populations was detected for any of the studied traits. Mean values of comparable leaf and cone morphological traits did not differ considerably from values reported elsewhere. Gender dimorphism in leaf morphology was detected, but it was not distributed uniformly throughout the studied area. An ANOVA model with both nested and crossed effects revealed that the largest proportion of the total variation was, as expected, contained within populations, partly as among-tree variation (18-47%, depending on the trait) and partly as within-tree variation (33-77%), which was remarkably high. Gender dimorphism explained only 0-3% of the total variation. Differences among populations (2-23%) were significant for all studied traits except one; however, PCA showed no clear geographical differentiation of the studied populations. This lack of phylogeographical structure may be the consequence of repeatedly occurring colonisation-retreat scenarios and suggests the existence of several small refugial populations scattered over a large part of the Balkan Peninsula in the Pleistocene. Further research including palaeobotanical and molecular genetic studies will be needed to better understand the forces that shaped current variation patterns of J. oxycedrus L. subsp. oxycedrus in the Balkan Peninsula.

We analyzed the process of stand degradation of individual forest ecosystems in the region of the zonal community Tilio-Carpino-Qurcetum robori-cerris Jov. 79 located in the western part of Fruska Gora National Park. Degradation occurred is consequence to regeneration felling and it progressed towards the extinction of oaks, first of all the valuable pedunculate oak and Vergilius's oak, and then also Turkey oak. The analyzed mature stands were degraded coppice and mainly predominated by the Turkey oak in the tree stratum. In juvenile stands, often initially well regenerated with Turkey oak, the dominant species in the tree stratum are lime, hornbeam, flowering ash, field maple and other secondary species, predominantly of coppice origin. Restitution of the degraded stands is possible by applying an adequate regeneration system. Taking into account the primarily protective function of the analyzed forest ecosystems and the fact that these are degraded and coppice stands, the system of regeneration should be based on combined restoration.

In the area of the western Balkans, xerothermal broad-leaf forests hold a very special position, the main species being pubescent oak (Quercus pubescens Willd.). The study comprises 36 populations of pubescent oak from Croatia, Bosnia and Herzegovina, Montenegro, Kosovo, Albania and Macedonia. Genetic variability and population diversity was analysed on chloroplast DNA in order to determine to which haplotype an individual or studied population belongs, as well as how they are related. For the detection of one haplotype analysed four sequences (AS, TF, DT and CD) on the chloroplasts DNA. The results of the analysis suggest that there are six different haplotypes of pubescent oak (2, 4, 5, 17, 31, 33) in the studied populations. Two more sub-haplotypes were found in haplotype 5 (a and b), but only in populations occurring in Croatia and Bosnia and Herzegovina. The results suggest the great variability of pubescent oak in the researched area, which is generally characteristic of other species from the area of the Balkan Peninsula. The results obtained by means of cpDNA analysis can help in the formation of seed zones. However, due to the strong selection pressure of unplanned logging, and the possible introduction of herbal material of unknown origin, it is necessary to find a sufficient number of autochthonous entities (i.e., populations of the researched species) as well as new suitable markers for their characterization. The results of this paper constitute a scientifically recognised, partial examination of the origin of the starting forest reproductive material from the broader geographic area, thus serving future projects on its regeneration