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  • Simplified volume equations for grey poplar (Populus × canescens Smith.) standing trees

    Grey poplar (Populus× canescens Smith.) is a natural hybrid of white poplar (Populus alba L.) and Eurasian aspen (Populus tremula L.). It can be found throughout Europe, where both parents are present. The above mentioned species of poplars (under the term of ‘domestic poplars’) cover approximately 5% of the forests of Hungary. Of these species, grey poplar holds significance in forestry, and its role in afforestation shows a growing tendency. For this reason, improving the growing technology of grey poplar is a timely topic. In this paper we introduce algorithms which help estimate grey poplar tree volumes without having to use volume tables. Based on the performed evaluations, both equations can be used for single tree volume estimation with an error of less than 5%.

  • A simplified growing model for mixed black locust (Robinia pseudoacacia L.) and poplar (Populus spp.) plantations in the Danube-Tisza Interfluve

    This study presents a static model of mixed black locust (Robinia pseudoacacia L.) plantation stand structures for inventory stand structures between 10 and 40 years of age. Due to its local character, the model can be advantageous in planning tending operations, making structural factor predictions for the standing stock (main stand) after tending cuts, and preparing local wood production and silvicultural models. The model data presented in this paper show that poplars account for 55–62 % of the volume per hectare due to their faster growth rate in mixed black locust and poplar plantations. Maintaining the black locust part of the stand necessitates harvesting the poplars by the age of 10 at the latest.

  • Yield and crown structure characteristics in a red oak (Quercus rubra L.) stand: Case study

    The paper provides the results of a detailed analysis of timber volume and several important crown variables of red oak (Quercus rubra L.) based on an experimental plot in eastern Hungary. At the age 32 years the crop trees belonged to different height classes. If the volume of the mean tree from height class I was considered as 100%, the volume of the mean tree of class II was 59%, and the mean tree of class III was only 36%. It appeared that there was a significant correlation between crown indices and yield. For this reason, diameter at breast height showed a positive linear correlation with crown diameter (R2= 0.6211). Additionally, there was also positive linear relationship between crown diameter and volume (R2= 0.6908). The variation of crown indices is height even within the same stand and indicates the importance of following a selective thinning operation method.

  • Comparative study of newly-bred black locust clones with regard to photosynthetic rate and water use efficiency: early evaluation

    Black locust (Robinia pseudoacacia L.) is one of the most important tree species in Hungary, due to its positive economic impacts. Research to increase its yield, improve its stem quality and enhance its drought tolerance has been ongoing since the 1960s. Of the current research works in this field, the clone trial of the Forest Research Institute, University of Sopron, established in 2020 in the Nyírség region, is worth highlighting. In this experiment 4 newly-bred clones and a state-approved black locust cultivar ('Üllői') are being tested. In the summer of 2022, ‘on site’ measurements of assimilation parameters – net assimilation (An), transpiration (Tr) – were carried out using the LI-6800 portable photosynthesis system. From the data obtained, the water use efficiency (WUE) was calculated. The results of the statistical analysis (Kruskal-Wallis H test) have shown significant differences (p < 0.05) between the clones for all three parameters (An, Tr, WUE) tested. The NK2 clone has performed the highest value for all the parameters studied. However, no significant differences were found between clones NK2 and PL040 for Tr or between NK2 and control ('Üllői') for WUE. Studies of this kind contribute to the improvement of black locust growing through the production and selection of cultivars, which are relatively resistant to the negative effects (drought) of climate change.

  • Yield table for selected black locust (Robinia pseudoacacia L.) cultivars

    In Hungary, the black locust (Robinia pseudoacacia L.) can be considered as the most important fast-growing, stand-forming introduced tree species. Due to its positive growing technological characteristics as well as wood utilization possibilities, at the present, black locust is the most widely planted tree species in Hungary, covering 25% of the country’s total forest area. One of the important tasks ahead of Hungarian black locust growers is to improve the quality of black locust stands with introducing selected cultivars. For the estimation of the growth rate and yield a numerical yield table has been constructed on the basis of surveys of the experimental plots established in pure,managed ’Nyirségi’ ,’Üllői’ and ’Jászkiséri’ black locust cultivars’ plantations which can be suitable for sawlogs production. In the course of 56 stand surveys the key stand characteristics were measured, and then, were reconsidered the average height, diameter (DBH), volume, basal area and stem number given separately for the main (remaining), secondary (removal) and total stands per hectare. The programmable editing procedure allows to extention and formal change of information content of the yield table according to different demands.

  • Growth and yield patterns of black locust (Robinia pseudoacacia L.) sample trees affected by site conditions: case studies

    The trees removed from the long-term experiment plots are available for the measurements as lying trees. Through the determination of the volume in sections along the stem, the stem form, the stem volume and other factors can be specified. The comparison of the stems of individual trees of first and third yield classes of black locust (Robinia pseudoacacia L.) stands shows that site conditions have a main effect on the yield (mean tree volume). The difference can be as high as 53% at the age of 30 depending on the sites. To determine the growth patterns based on tree volume is rather a new approach in the light of the relevant literature. The obtained results also highlight the importance of choosing the appropriate tree species for a given site.

  • Volume of Paulownia Shan Tong (Paulownia fortunei × Paulownia tomentosa) plantation in Eastern Hungary: a case study

    Volume tables for tree plantations are not unknown in international practice. In many places, this is due to the uniqueness of the species or variety composition of the plantations and the cultivation technology used. In most cases, this is also justified by specific soil (ecological) conditions. In Hungary, publications on Paulownia have not yet included a volume table. This is the first one we are publishing, thus it can be considered as a gap-filler. The research was conducted in Monostorpályi, a 1.8 hectare, 8-year-old municipal plantation. 8 trees were selected randomly and their parameters were studied.

  • The effects of tending cuttings on yield and value changes in black locust (Robinia pseudoacacia L.) stands: a case study

    Thinning experiments in black locust (Robinia pseudoacacia L.) stands have been carried out for many years in Hungary. This species has great economic importance in the timber supply of the country. This paper evaluates the effects of tending cuttings in two aspects: the effect on yield and stand value. The case study has proved that in black locust stands tending cuttings can not increase the periodic total production but the stem-quality index can be increased by 2%.

  • Angle-count sampling method for estimating forest stand volume – a practical approach

    Point sampling, which is also known as angle-count sampling (ACS), can be considered an efficient way of estimating the basal area and volume of forest stands. It is possible to use it in forest management: providing more accurate estimates (precision <10%) of  site and stand characteristics needed for management planning. 20 black locust (Robinina pseudoacacia L.) stands were selected at final cutting age to determine the regeneration criteria based on their total volume. It was verified that at P=5% there was no difference between the main volume values of stands indicated in the relevant forest plans as well as calculated by the ACS method.


  • Productivity of thinned black locust (Robinia pseudoacacia L.) stands in Hungary: case studies

    Black locust (Robinia pseudoacacia L.) is one of the most important introduced tree species in Hungary, covering more than 24% of the stocked area and providing approximately 20% of the country’s annual timber cut. Consequently, the research and development activities related to the improvement of the growing technology of black locust are also important, especially in mitigating the negative effects of climate change. The aim of this study was to quantify growth and yield, responses of even-aged 12–31–year–old black locust stand to thinning in Hungary. The study has proved that irrespective of the yield class, age and thinning intensity, thinning could not increase effectively the cumulative volume production. As percentage of the control it has changed between +0.6 and -8.4%. On the other hand, it could increase the stand value based on stem quality index by 10–21%.