The aims of this paper were the analysis of climate elements and Thornthwaite’s climate index, the study of the development of diameter and current diameter increment of the Austrian pine trees from several artificial stands in the Belgrade area, as well as an analysis of the influences of the pluviometric regime and climate index on the current diameter increment of the Austrian pine over the period 1985-2010. By comparative analysis and statistical data procession, the correlation between the diameter increment and climate characteristics was determined. In spite of the wide-held view that the Austrian pine is a species that cannot make use of the capacity of the best sites where it grows, is to a great extent able to react to increased humidity, one of the most important site factors upon which the growth of basic quantitative tree parameters directly depends. [Projekat Ministarstva nauke Republike Srbije, br. TR 31070: The development of technological procedures in forestry with a view to an optimum forest cover realization

This paper presents research results on forest decline in Serbia. The results were obtained through monitoring defoliation of 34 tree species at 130 sample plots during the period from 2004 to 2018. This research aimed to determine whether the occurrence of defoliation and tree mortality were caused by drought. Defoliation was assessed in 5% steps according to the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) methodology. All the trees recorded as dead were singled out, and annual mortality rates were calculated. To determine changes in air temperature and precipitation regimes during the study period, we processed and analysed climatic data related to air temperature and precipitation throughout the year and in the growing season at 28 main weather stations in Serbia. Tree mortality patterns were established by classifying trees into three groups. The first group of trees exhibited a gradual increase in defoliation during the last few years of monitoring, with dying as the final outcome. The second group was characterised by sudden death of trees. The third group of trees reached a higher degree of defoliation immediately after the first monitoring year, and the trees died after several years. Tree mortality rates were compared between years using the Standardised Precipitation Evaporation Index (SPI) and the Standardised Precipitation Evapotranspiration Index (SPEI), the most common methods used to monitor drought. The most intensive forest decline was recorded during the period from 2013 to 2016, when the largest percentage of the total number of all trees died. According to the annual mortality rates calculated for the three observation periods (2004–2008, 2009–2013, and 2014–2018) the highest forest decline rate was recorded in the period from 2014 to 2018, with no statistically significant difference between broadleaved and coniferous tree species. As the sample of coniferous species was small, the number of sample plots should be increased in order to achieve better systematic forest condition monitoring in Serbia. The analysis of the relationship between defoliation and climatic parameters proved the correlation between them. It was noted that the forest decline in Serbia was preceded by an extremely dry period with high temperatures from 2011 to 2013, supporting the hypothesis that it was caused by drought. We therefore conclude that these unfavourable climatic conditions had serious and long-term consequences on forest ecosystems in Serbia.

The aim of this research was to examine the influence of acorn size on morphological characteristics of one-year-old Northern red oak (Quercus rubra L.) seedlings. The quality of seedlings correlates with the quality of the seed they are derived from. In species with large seeds, as in the case of Northern red oak, the seedling growth in the first growing season is closely related to seed size or the amount of reserve nutrients that are stored in the seed. The height and root collar diameter of one-year-old Northern red oak seedlings increases with increase in acorn size. The results obtained in this research can be used as a guideline for acorn grading, because they show that improved Northern red oak seedlings quality can be achieved using seeds of appropriate size. [Projekat Ministarstva nauke Republike Srbije, br. TR 31070: The development of technological procedures in forestry with a view to an optimum forest cover realization]

In this paper are presented the results of an analysis of intrapopulation variability using morphometric markers of 20 Bald cypress test trees originating from seed stand S 01.10.01.01 near Backa Palanka. The morphometric characters of cones (length, width and number of grains) and seedlings (root collar diameter and height of seedling) that were produced by this seed were analyzed. A mutual biological similarity or distance of mother trees depending on the analyzed characters was tested. The determined values of the dimensions of cones and seedlings indicate the good genetic and adaptive potential of this species, which can be a starting point for the mass production of Bald cypress seed and planting materials in Serbia.

Background and purpose: Knowledge of the interaction between plant and climatic conditions is of great importance in establishment of new forests, especially in the introduction. Taxodium is an allochthonous species in Europe and this paper presents the data on the success of its introduction and adaptability to site conditions. Material and methods: For the analysis of the climate characteristics in Bačka Palanka have been used the data of the Republic Hydrometeorological Service of Serbia for the period 1981-2010 regarding meteorological station Rimski Šančevi. Dendrometric analysis was performed on the dominant trees of Taxodium by taking an increment core at breast height using Pressler drill. On the increment cores was measured diameter increment per each year of the observed period. By the regression analysis was determined the correlation between the diameter increment and climate elements. Results and conclusion: By research of influence of climate factors on the diameter increment of Taxodium trees can be concluded that with increasing of values of mean an-Original scientific paper nual temperature and mean temperature during the growing season comes to a reduction in size of the diameter increment. The increase of the quantity of precipitation over a year, particularly during the growing season, leads to the increase of the diameter increment, and vice versa.