Impact of Mixing on the Structural Diversity of Serbian Spruce and Macedonian Pine Endemic to Relict Forest Communities in the Balkan Peninsula

The aim of this paper is to analyze the effect of different degrees of mixing on the diversity structure in stands left to spontaneous development. The research included two communities of species endemic to the Balkan Peninsula—the Serbian spruce (Picea omorika Pančić Purk.) and the Macedonian pine (Pinus peuce Griseb). Data from eight sample plots were used in the research. The changes in diameter and height structure, spatial arrangement of trees, and diameter differentiation were analyzed. The analyzed parameters of structural diversity show relatively low to moderate values. Results showed an increase in mixing was reflected in the width and shape of distributions. A spatial analysis of stands with a higher degree of mixing showed a tendency towards a random to regular distribution of individuals, in contrast to stands with a lower degree of mixing which showed a tendency towards a clump distribution. The pronounced species’ dimensional and spatial diversity confirms their importance to the condition of modern forest management. Significant differences in the change of structure are shown by stands with a share of admixed species of above 20% by volume. The obtained results refer to stands left to spontaneous development, suggesting than an active research and management approach must be assumed to realize the goal of protecting rare forest ecosystems.

Is the double-spined bark beetle Ips duplicatus a new threat to Picea omorika in urban habitats?

The double-spined bark beetle Ips duplicatus (Coleoptera: Curculionidae, Scolytinae) is an invasive forest pest having a broad range of coniferous hosts within Europe. We found this species to be also developing in the Serbian spruce Picea omorika. Ips duplicatus infested 14 (52%) of 27 P. omorika mature trees in an arboretum garden in northern Slovakia in Central Europe during the summer of 2019. Logs from the upper part of stems of P. omorika trees placed in eclectors in the laboratory, yielded a total of 179 individuals of three scolytine species, with prevalence of I. duplicatus. Our results show that I. duplicatus also colonized less likely host such as the Serbian spruce, causing threat to this ornamental tree and contributing to its mortality in urban habitats during hot and dry summer weather.

MOR and MOE of Serbian Spruce (Picea omorika Pančić/Purkyně) Wood from Natural Stands

The paper presents the results of testing the bending stress of Serbian spruce wood from natural stands. In testing the samples, in addition to the modulus of rupture, the bending stress at the proportionality limit, the ratio between the stress at the proportionality limit and the modulus of rupture as well as the modulus of elasticity of wood were determined. The study included nine trees from natural stands, and a total of 261 samples were tested. Regression analysis determined the dependences of these mechanical properties on the annual ring width, the proportion of late wood and wood density, as well as the dependence of the modulus of elasticity on the modulus of rupture.

Uspevanje omorike (Picea omorika (Pančić) Purk.) v generativnem semenskem nasadu Počivalnik pri Postojni

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 trees were planted in 1988 and are currently classified as a pole stand. We measured the diameters of the trees and systematically evaluated the vitality of each tree throughout the plantation. Data processing consisted of calculating the percentage of trees of each health status for each provenance and phenotype present in the plantation, creating a plantation model, and performing an analysis of variance and Tukey's post-hoc test. We found that provenance has a significant effect on the vitality of trees but not on tree diameter. Phenotype affects both the vitality of trees and tree diameter. The correlation between phenotype and tree diameter is significant within phenotypes B (type %semidichotomy%) and C (type %serbica%). Also, the impact of phenotype on diameter increment varies between the different provenances. According to our investigations, the most suitable seed material for the Dinaric karst region of Slovenia is from the Šargan provenance (read Shargan). In terms of phenotype, types C ('serbica') and F ('argentea') seem to be the most suitable. They are also the most desirable for horticultural use.

Variability of morphological and anatomical characteristics of Serbian spruce (Picea omorika /Panc./ Purkyne) needles of natural population located in the Milesevka river canyon

Serbian spruce (Picea omorika /Panc./ Purkyne) is rare and endangered tertiary relict and endemic species in the Balkan Peninsula. Its natural distribution is fragmented and restricted to western Serbia and eastern Bosnia and Herzegovina, mainly in the canyon of middle course of the Drina river. Since the mid-19th century, the number and size of populations have been steadily decreasing accompanied by a decline in the number of mature individuals, endangering natural regeneration is endangered. The objective of this study is to determine variability within Serbian spruce (Picea omorika /Panc./ Purkyne) natural population in the canyon of the Milesevka river on the basis of morphological and anatomical characteristics of needles and, thus, to broaden knowledge on this rare and endangered species. Twigs with needles collected from all mature individuals that represent the population were used as material for the study. The following morphological and anatomical characteristics were measured: NL- needle length; NH - needle height; NW - needle width; CT+EH - cuticle + epidermis height; HH - hypodermis height; VB - vascular bundle diameter; No of SC - number of resin channels; SC diameter - resin channel diameter. The average values of the measured characteristics are: needle length 13.23 mm; needle width 1239.93 ?m; needle height 608.63 ?m; cuticle + epidermis height 11.49; hypodermis height 17.59 ?m; vascular bundle diameter 220.64 ?m; number of resin channels 0.74; resin channel diameter 52.36 ?m. The characteristics with the highest variability are as follows: number of resin channels (161.64%); resin channel diameter (25.35%); hypodermis height (20.79%), while the needle width is a characteristic with the lowest variability (6.39%). The results of the analysis of variance showed very high statistical differences within population for all studied characteristics (p<0.01; ?=0.05). In order to make the results clearer, it is necessary to investigate the genetic diversity and population structure by analyzing various phenotypic characteristics in specially designed experiments (e.g. progeny tests) as well as by analyzing appropriate DNA markers. The studied population must be involved in continuous conservation and breeding processes, especially through appropriate forms of ex situ conservation.

VARIABILITY OF CONES AND SEEDSCALESIN PICEA SPECIES AND THEIR FORMS IN CONDITIONS OF THE CITY OF OMSK

The study addressedthe morphometric indicators of cones and seed scales, such as length, width, and weight (before opening and after drying). Similarly, seed scales were measured, the marginal lines were described, and the number of seed scales in the cones was counted. The summary tables showed significant differences in the length and width of cones (Student's criterion). The correlation analysis was used to quantify the association between various indicators and the seed scale size. The samples were collected in the Genze Dendrological Garden, a natural landmark of regional significance. The study was carried out usingMolchanov and Smirnov’s (1967) method in the summer-autumn period. Siberian spruce (both blue and green forms), Serbian spruce, Colorado spruce (green form), and Canadian spruce had medium and large cones, which indicates a high adaptive capacity of these species. The length of cones in blue-grey and golden forms of Colorado spruce was below the average, indicating a low adaptive ability of the introduced species in the West Siberian foreststeppe. The correlation analysis showed a moderate dependence of the weight of seed scales and the weight of cones after drying (K = 0.60). A small dependence was found between the weight of seed scales and the length of cone after drying (K = 0.39). The size of seed scales strongly correlated with the size of cones (K ˃ 0.8). Student's t-test did not reveal significant differences in the width of cones in the studied species and forms of spruce, except for green form of Colorado spruce as compared to Serbian spruce and Canadian spruce, and blue-grey form of Colorado spruce as compared to Canadian spruce , showing notable differences at 1% significance point. By the length of cones, the studied species can be categorized into twoessentially different groups, the first one including all forms of Siberian spruce and Colorado spruce and the second one including Serbian spruce and Canadian spruce .

Assessing the growth of Picea omorika [Pan.] Purkyn in the Masaryk Forest Training Forest Enterprise at Ktiny

Plantations of Serbian spruce (Picea omorika [Panč.] Purkyně) reach an age over 70 years at the Masaryk Forest Training Forest Enterprise (TFE) at Křtiny. They occur at different sites of the TFE, which is situated north of Brno between Blansko, Jedovnice and Brno in the Czech Republic. The paper presents an assessment of primary mensurational values (diameter at breast height d.b.h., height h, Derbholz volume m³), fertility, mortality and general health condition. The present registered number of Serbian spruce trees is 425 (from originally 750 individuals) in 25 localities and 12 GFT (groups of forest types). A comparison of Serbian spruce mensurational data with growth tables indicated that Serbian spruce on GFT 4K makes up for the tabular mean values of Norway spruce (Picea abies [L.] Karst.) in yield class +1.