The regeneration of oak forests in the hilly and mountainous areas is one of the most serious and complex problems forestry practitioners face in Serbia. The success of regeneration depends on the individual or combined (often synergistic) influence of numerous biotic, abiotic, and management factors. While there is significant knowledge and experience about this process in practice so far, there is still great uncertainty regarding its proper execution and control over the influencing factors. The paper critically evaluated the available literature and current experiences from practice through a questionnaire. A comprehensive literature search was conducted, taking into consideration various databases and search engines, mostly composed of peer-reviewed publications from ISI-listed journals. A total of 187 papers were included in the base. Aiming to better understand the current state and the main problems in the regeneration of hilly-mountainous oak forests in Serbia, surveys were performed among forest practitioners. Based on this, the paper synthesized the current knowledge and addressed future perspectives in hilly-mountainous oaks management. More specifically, the factors that dominantly influence the regeneration process, their modes of action, behavior in the case of modifications, as well as the possibilities of their interaction are defined. The success of regeneration is determined by canopy openness, microclimatic conditions, presence of competitive vegetation, initial number of seedlings, and seedling growth and health, as revealed in the literature. The proposed methods for more successful regeneration and restoration of oak forests, include producing high-quality seedlings, using advanced weeding methods, developing a specific strategy for restoring native oak forests, assessing genetic resources and long-term monitoring. Overall conclusion of the conducted literature analysis is that there is a great need for conducting further long-term research on improving the regeneration systems in hilly-mountainous oak forests in Serbia.

Provenance trials, as the subject of continuous analyses, provide empirical information about the plasticity of tree species. Changing climate and environmental conditions likely favor genotypes with high levels of plasticity. Finding the suitable provenance for the reintroduction of pedunculate oak to habitats that are threatened and where this species no longer exists provides important information for the targeted use of the available gene pool. The dominant ecological factors in the development of pedunculate oak forests are groundwater level and changes in the hydrological regime of habitats. In this study, we established nursery and field provenance trials to test two pedunculate oak seed provenances from different hydrological conditions to investigate the influence of seedlings' provenance and field microhabitat on growth parameters and survival. In the nursery trial, the height and ground level diameter were measured. After three years in the pilot object, the height and diameter were analyzed again, as well as the survival. To determine the microhabitat influence planting area was divided in two ways: three repetitions and two planting blocks. In this study, significant differences in analyzed growth parameters between the chosen provenances were obtained at the end of the first vegetation period. In later ontogenetic phases influence of the provenance is missing. As the difference between provenances disappears, the influence of microhabitat occurs (significant differences between repetition or planting blocks). After the second year of development, no significant difference was observed between the two provenances of different hydrological regimes, but there are significant differences between the microhabitats in the afforested area (established pilot object).

The Austrian pine (Pinus nigra Arnold) is a species often used in afforestation/reforestation programs in Serbia and region. Seedlings quality has a great role in outplanting survival and growth. Nursery cultural practice has a central influence on seedlings morphological attributes, so we tested seedlings quality from different seedbed densities and seedlings patterns and their outplanting success. Two-year-old bareroot seedlings were grown in very high densities (110 seedlings m-1 in rows and 750 seedlings m-2 across all seedbed space) and high densities (65 seedlings m-1in rows and 450 seedlings m-2 across all seedbed space). Morphological attributes (root collar diameter - RCD, height - H, sturdiness coefficient - SQ, root length – Rl, dry weight of shoot - SDW and root - RDW, shoot to root ration - S:R and quality index - QI) of seedlings from different densities were tested in the nursery before outplanting and compare with seedlings survival and growth (root collar diameter – RCD1 and height – H1) one year after field growing. Seedlings from different densities had accepted RCD (>3 mm) for field planting and there were significant differences in their morphological attributes, except Rl and S:R. The best survival was recorded at seedlings from highest seedbed densities (93.33%), opposite with many previous researches. Seedlings grown across all seedbed space (450 seedlings per m-2) keep their advantage in growth after first year, although survival was lowest (46.67%).

The leaf area of plant leave scan be considered as an indicator of the plant growth conditions, and its variability is usually associated with adaptation and response to the changing environment. The aim of this study is to investigate the relation of the leaf area parameters on growth of the narrow-leaved ash 1+0 seedlings from the nursery trial and determining variability between the 18 half-sib lines. The seedlings were obtained from seeds collected from 18 maternal trees found in the area of the special nature reserve Upper Danube Region. Ten randomly selected 1+0 seedlings per half-sib line were selected for further study, and all leaves per seedling were collected, herbarized and scanned. The leaf area of each leaf (LACL) was measured using an open-source image processing program – ImageJ, and the total leaf area per seedling (TLA) was calculated. Also, the number of leaves per plant (NCL) as well as the number of leaflets within each imparipinnate compound leaf (NLCL) were counted. The results showed that differences between studied attributes were statistically significant among 18 selected half-sib lines (p < 0.05). The most variable parameter was the total leaf area per seedling (TLA; CV=68.98%), which is strongly correlated to the leaf area per each leaf (LACL; r=0.95) and the number of leaflets (NLCL; r=0.94). In this study, we confirmed that leaf parameters were highly correlated to the growth of one-year-old Fraxinus angustifolia seedlings.

Austrian pine (Pinus nigra Arnold) seedlings are frequently used for afforestation/reforestation and restoration practice in Serbia. Indeed, the seedlings of various stock types are produced by almost all forest nurseries in Serbia and bareroot seedlings are mostly common. The aim of this study is to analyze the method of sowing and sowing density on some morphological characteristics and quality of one-year-old Austrian pine seedlings. Sowing in rows and random sowing across all seedbed space were performed. In both cases, the sowing density (R1 - 8 g m-1, R2 - 40 g m-2) and half of the recommended sowing density (S1 - 4 g m-1, S2 - 20 g m-2) were applied. Seedlings from both treatments had average height and root collar diameter values in the range of 4.91 to 5.73 cm, and 1.25 to 2.34 mm, respectively. Observed characteristics of seedlings (height - H, root collar diameter - RCD, root length - RL, dry weight of shoot - SDW, root - RDW and seedlings - SLDW, sturdiness coefficient - SQ and quality index - QI) were conditioned by treatment (One-Way ANOVA, p<0.05). Shoot to root ration was similar at seedlings of all treatments and ranged from 1.33 to 1.63. In both cases, decreased density produced better results. The combination of lower sowing density (20 g m-2) and sowing in all seedbed areas (S2) provided the best seedlings with QI - 0.21.

The paper presents the growth characteristics of one-year-old seedlings of three autochthonous oak species (Fagaceae family): Turkey oak (Quercus cerris L.), Hungarian oak (Quercus frainetto Ten.) and downy oak (Quercus pubescens Willd.) in suboptimal growing conditions. The analyzed oak species are widely distributed in Serbia. One of the most important benefits of oak species is wood production (Hungarian and Turkey oak), and they have a promising role for the use in the future regarding the climate change as all species can be encountered on dry sites. Acorns were collected in the autumn of 2017 in natural stands and a sample of 400 acorns per each oak species was immediately sown in a nursery seedbed in the form of a random block system with four replicates. At the end of 2018, the available sample of seedlings was analyzed morphometrically. The seedlings were classified according to the number of shoot growth flushes into one-flush-growth and multi-flush growth seedlings. Turkey Oak had the highest number of seedlings which also recorded higher values in total height, root collar diameter and number of leaves. These results were obtained on alkaline soil with the presence of weeds and rodents and the absence of irrigating. The presence of multi-flush growth was recorded in all three oak species. Differences between analyzed three oak species exist in these suboptimal conditions. However, in full light conditions, a similar growth pattern was recorded, indicating to the similar adaptability of the species.

Beech is the most important tree species in forests of Serbia. However, despite its significance, the taxonomic status of beech in Serbia is unclear. Morphology of the cupules can be successfully used to distinguish species and within species taxa. In this paper we report results on cupules morphology, measuring the same attributes reported by Mišić (1955): 1) Length of the longest valve of cupule, 2) Width of that valve (at widest point), 3) Distance between base of the longest valve and peduncle, 4) Length of cupule without peduncle, and 5) Length of peduncle. The length of cupule and peduncle length from 12 populations in Serbia are in the range reported for Fagus sylvaticain Serbia and western Eurasia. Results of cluster analysis shows a grouping of populations in two groups:1) the southeast group, and 2) group consist of populations from northwest, east and southeast of Serbia. Populations from this southeast group also consist the group of populations on altitude over 850 m, indicating presence of ecotypes. The exception is population from Stara Planina (1,520 m a.s.l.) which is grouped with populations from altitudes under 850 m. Keywords: European Beech; cupules; variability

Aiming to produce forest reproductive material at the family level, we tested quality of twenty Fraxinus angustifolia Vahl half-sib lines in the nursery experiment. We measured height (HT) and root collar diameter (DIA) of one-year old seedlings, and we monitored germination rate and mortality during the first growing season. Seeds of 20 half-sib lines originating from Sombor area (north Serbia) were sown in seedbed on autumn 2016. The seed dormancy was not broken in all seeds equally, resulting with un-uniform germination over a two months period. All measured attributes shows a statistically significant differences, indicating a strong effect of genetic control. The highest average and DIA were measured in half-sib line 7 (22.62 cm; 5.79 mm, respectively). The lowest average DIA was measured in half-sib lines 18 (2.85 mm) and 19 (2.94 mm), which can be result of growing density effect (104 seedlings m-2 for line 18 and 126 seedlings m-2 for line 19, compared to 40 seedlings m-2 for line 7). The correlation between DIA and HT is strong and positive (R=0.90). Due to its morphological superiority, half-sib line 7 could be recommended for mass production of Fraxinus angustifolia seedlings at the family level. Keywords: Height; Root Collar Diameter; Seedlings Quality; Narrow leaved ash

During a three-year survey in 14 forest nurseries in Serbia we measured seedlings of 19 species and 96 stocktypes of both conifers and broadleaves. Seedlings were measured in the nurseries for height and diameter, and subsamples was taken for measurements of shoot and root dry weight, and presence of mycorrhiza. Results of mean values and variation of measured morphological attributes are presented and compared to Serbian standard for seedlings quality. We found mycorrhiza on seedlings root from almost every nursery, seedbed and tray. Our results show that current nursery cultural practice need to be improved and that seedlings quality standards should be updated.

In this nursery experiment, 100 one-year-old northern red oak seedlings were measured at the end of the 2016 growing season. Measured growth elements were: total height, root collar diameter and total leaf area. All seedlings were classified according to the presence of polycyclism into four types: one-flush growth, two-flush growth, three-flush growth, and four-flush growth type. The number of new flushes (shoots) is a good indicator of total height, root collar diameter and total leaf area.