Establishment of white poplar clonal plantations by stools

The results of white poplar clonal plantation establishment by stools are presented. The trials were established at three sites, characterized by favorable water regime for growth and development of poplars. Also, the effect of different factors on survival rate, diameter at breast height and plants' height was analyzed. Results suggest that similar high survival rate (90-100%) was achieved by planting of stools on depth of 2.5 m (deep planting), as it was achieved by planting of rooted cuttings at the depth of 0.8 m, which is a comon practise in the establishment of white poplar plantations. The survival rate of planted stools did not decrease signifficantly between the end of the first and second growing season. Selected clones achieved survival rate of Villafranca clone with both methods of planting. Two-year old rootless shoots (2/0 type of plantings) achieved higher survival rate than the one-year old ones (1/0 type) and two-year old rooted cuttings (2/2 type). Survival rate of one-year old rootless shoots (1/0 type) planted at the depth of 0.8 m was not significantly lower than of those planted at the depth of 2.5 m, but it was notably lower than survival rate of rooted cuttings (1/1 type). Establishment of white poplar clones by stools could significantly improve white poplar wood production, considering the benefits of plants production in stool beds. The potential for improvement of the establishment of white poplar plantations on sandy soils with relatively deep level of underground water, and the potential for successful planting of difficult-to-root white poplar genotypes, should be the subject of further studies.

A comparison of the accuracy of different types of samples for spatial structure indices determination in beech forests in Serbia

In this paper we compared the accuracy of different samples (minus the sample with the NN1 edge correction and buffer zone, plus sample and modified cluster sample) to determine indices of spatial structure in beech forests in Serbia, which can be used in regular forest inventory. The research was conducted in 11 forest stands of different structure at the territory of Central Serbia. Field data used for the assessment of spatial structure indices were collected across the examined stands on the sample plots of different sizes, using systematic grid, with the square layout of sample plots (100x100 meters). The study was conducted on 242 sample plots. For accuracy comparison of different sample types, five indices were used: Uniform angle index, Mean directional index, Species mingling index, DBH differentiation and DBH dominance indices. One-way ANOVA showed that at the stand level there were no statistically significant differences between mean values of indices obtained by different sample types. However, Simple linear correlations confirmed for most indices that if the spatial structure is to be determined with accuracy at the level of sample plots (in this case, a circular fixed radius plot of 5 acres) it is necessary to use a plus sample during data collection. For species mingling and DBH differentiation indices, Simple linear correlations show that both minus sampling with edge correction buffer zone and modified cluster sampling with somewhat less accuracy can be used to a certain extent. Minus sampling with NN1 edge correction is not practical for use on sample plots of this size in beech forests in Serbia.

Climate change within Serbian forests: Current state and future perspectives

Extreme weather conditions, namely droughts, heat waves, heavy rains, floods, and landslides are becoming more frequent globally and in Serbia as a result of climate change. Generally, various parts of human society are affected by changing climate conditions. Forest ecosystems are one of the most sensitive systems to weather and climate. In that sense, small changes may lead to large disturbances including forest decline, outbreaks of insect pests and diseases and eventually mortality. In Serbia, the average temperature in forest ecosystems of the most important and abundant forest tree species has risen for more than 1°C in the last thirty years (1990-2019) in comparison to the previous period (1961-1990). During the last thirty years, the northern and western parts of Serbia experienced an increase in precipitation as opposed to the southern and eastern parts of the country. If one takes a closer look at the climate within a particular forest stands, it would seem that the effect of precipitation decrease is stronger in less humid parts of a tree species range. In this paper, we discuss various aspects of climate change impacts on forests and forestry, including forest ecology, genetics, physiology, pests and diseases, ground vegetation, monitoring, reporting and verification system, climate change litigation and perspectives of forests in the 21st century in Serbia.

Environmental assessment of greenhouse gases' emission in poplar plantation under extreme climate conditions of winter 2019/2020

Global changes, triggered by increased anthropogenic emissions of greenhouse gases, are the main problem of modern ecology. Soil is the main terrestrial reservoir of carbon, in both organic and inorganic forms. Forests are the major asset in carbon cycling and the mitigation of global climate change in the terrestrial ecosystem, because forest ecosystems in a temperate climate area are the major sink of CO2 from the atmosphere. Carbon dioxide emission from the soil is the major component of greenhouse gas emission, as well as the main respiratory flux from most forest ecosystems. In circumstances of changed climate and increased frequency of extreme climate events, soil greenhouse gas emission from forest ecosystems is gaining more and more importance, having in mind that soil temperature is one of the main limitation factors of greenhouse gas emission from the soil. From the results obtained from the experiment it is evident that the unusually warm winter of 2019/20 had as a consequence higher emission of greenhouse gases from all three experimental plots. Differences in emission between plots and between days can be explained by three main factors: soil composition, temperature difference between days of sampling, and soil moisture content. With an increased frequency of extreme climate events, as a consequence of global climate changes, the occurrence of higher winter temperatures is expected to be more frequent in the future, affecting also higher emission of greenhouse gases from the soil.

Influence of stand and terrain characteristics on the productivity of the Timberjack 240b tractor in pure beech stands

This paper presents the results of research of the Timberjack 240b tractor equipped with a double-drum winch (work form 1 Tractor driver + 0 Assistant) in beech stand at an average elevation of 983.73 m. The research was conducted using the time and work study method, with the help of GIS technology in certain segments of research. The achieved working hours consist of 75.44% effective time and 24.56% delay time. The delay time coefficient is 1.33. In total, 47 transport cycles were realized, with 66 stopping points, an average of 1.41 per transport cycle. The average skidding distance was 221.19 m. In total, 363 logs (204.04 m3) were collected by 79 winches. The average load volume was 4.34 m3 and consisted of 5.43 pieces. Loaded tractor skidding time is strongly influenced by skidding distance and load volume in interaction with the longitudinal slope of skidding trails. To increase tractor productivity, it was concluded that the skidding roads should be built with the smallest longitudinal slope possible. Preferably, logs should be skidded downhill.

Selecting tree species for reclamation of coal mine tailings based on physiological parameters

In the present study we compared the physiological performances of Prunus avium L., Robinia pseudoacacia L., Juglans nigra L., and Populus x euramericana cl. Pannonia, planted at the coal mine tailings of the Mining Basin "Kolubara" (Serbia), to assess the potential of different tree species for land reclamation. The measurements were conducted during three consecutive years characterized by contrasting climatic conditions (wet and drought). The results showed that the rate of net photosynthesis (A), stomatal conductance (gs) and transpiration rate (E) sharply declined in two dry years in all tree species. These trends were particularly evident for R. pseudoacacia and J. nigra, in which A, gs and E were twice as low during the dry years. On the other hand, R. pseudoacacia and P. x euramericana cl. Pannonia seedlings were characterized by the highest water-use efficiency and intrinsic water-use efficiency during the dry years, indicating that these species are more efficient responders to drought, due to their ability to maintain a balance between the loss of water and the CO2 assimilation rates. The survival rate of the examined tree species was high (>86%) and increased in the following order: P. avium < J. nigra < R. pseudoacacia < P. x euramericana cl. Pannonia. Based on the obtained results we recommend R. pseudoacacia and P. x euramericana cl. Pannonia as a good solution for afforestation and revitalization of degraded habitats, such as coal mine tailings, although high survival rate, observed in P. avium and J. nigra, makes these two species a candidate for planting during degraded sites reclamation, as well.

The impact of climate change on the growth of European beech at optimal altitudes in the Republic of Srpska

Many studies have shown that small climate changes can strongly affect the forest trees growth rate, many times causing changes in species habitats. In general, drought is mentioned as the main problem, so it is necessary to carry out its identification and quantification to investigate its effects on forests in Republic of Srpska. This study aims to analyse the relationship between the growth of European beech (Fagus sylvatica L.) at optimal altitudes in the Republic of Srpska and its climate characteristics represented by the Forestry Aridity Index (FAI) and Ellenberg's climate quotient (EQ) for 1950-2015 timespan. FAI and EQ were calculated using climate data (temperature and precipitation) extracted from a gridded dataset (E-OBS). Sampling was carried out in two localities near Vlasenica and Mrkonjić Grad at 1050 and 1030 meters above sea level (m a.s.l.), sampling the cores from 15 dominant trees at each locality. Using the Pearson Correlation Analysis, a negative impact on tree rings width (TRW) with rising index values was identified. This is especially pronounced for the index values of the year prior to the ring formation. In general, stronger negative correlations between TRW and EQ are found for the locality near Mrkonjić Grad, while FAI index showed a greater negative impact on TRW for the locality near Vlasenica.

Phytoecia (musaria) argus (Frölich, 1793): A new longhorn beetle (Coleoptera: Cerambycidae) for the fauna of Serbia

In total, 550 species of longhorn beetles (Cerambycidae) exist in Europe. The most recent checklist of Cerambycidae family of Serbia cited 265 species and 92 subspecies, belonging to 109 genera, 48 tribes, and six subfamilies in the country. However, the presence of 28 species reported from Serbia is questionable. Here we present the first finding of Phytoecia (Musaria) argus (Frölich, 1793) for the fauna of Serbia. The species was collected in May and June 2018 on Stol mountain (near the town of Bor, Eastern Serbia). Additionally, data on morphology, bionomy and distribution of the longhorn beetle species are given. With this finding, the total number of longhorn beetle species in Serbia is estimated at 266. This species could be used as an indicator for the assessment of the nature value and conservation status of natural habitats in Serbia and Europe.

Efficacy of some insecticides for control of oak lace bug (Corythucha arcuata Say)

The oak lace bug (Corythucha arcuata Say) was introduced to Europe from North America in 2000 and was first recorded in Serbia in 2013. It is a very serious oak pest which has harmful effect in both adult and nymph stages of the insect that feeds by sucking the sap on the lower (abaxial) leaf side. As this is a relatively new pest in our country, the possibility of its control by applying insecticides was tested during 2021. The paper presents the test results of three insecticidal active substances: deltamethrin, flonicamid and acetamiprid for the control of oak lace bugs. The insecticide flonicamid did not show sufficient efficacy in the suppression of the oak lace bug, while deltamethrin and acetamiprid have high efficiency for the suppression of the adults and nymphs of the oak lace bug, which recommended them for this purpose.

Erebia aethiops (Esper, 1777) (Lepidoptera: Nymphalidae): A new member of the fauna of higher elevations of the Kopaonik mountain

Erebia aethiops (Esper, 1777) is an Eurasian butterfly species. Results of the previous studies revealed the presence of only four species belonging to the genus Erebia (Dalman, 1816) on Kopaonik mountain (Mt. Kopaonik), including Erebia ligea (Linnaeus, 1758), Erebia euryale (Esper, 1805), Erebia medusa (Denis & Schiffermüller, 1775) and Erebia ottomana (Herrich-Schäffer, 1847). A recent finding of the species Erebia oeme (Hübner, 1804) pointed to insufficient research of this group of mountain butterflies on Mt. Kopaonik. This is confirmed by the last finding of Erebia aethiops (Esper, 1777) on two locations at high elevations of Mt. Kopaonik.