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Abstract
Introduction
Natural area for Turkish hazelnut, or Turkish filbert (Corylus colurna L.), is the Caucasus, Asia Minor and the Balkans. Into Ukraine, it was introduced more than 200 years ago. A number of investigators (P. Krotkevich, H. Tulupiy, A. Lypa, F. Pavlenko, I. Kosenko, I. Sytnik, S. Los, O. Kolchanova) studied this species in different years. Despite the advantages over other species of woody plants, this species is under-used to create plantations for different purposes. The reasons are insufficient information on growth and development in the conditions of introduction and the absence of forest seed establishment.
The aim of the study was to determine the potential of Turkish hazelnut for the North-East of Ukraine based on a complex assessment of Turkish hazelnut stands in the green belt at Kharkiv National Agrarian University.
Materials and Methods
The research was carried out in the arboretum and the Veterans’ Park in Kharkiv National Agrarian University. The growth of 22 to 40 years old Turkish hazelnut trees was analyzed by height and diameter on five sites. A number of characteristics, such as trunk diameter at a height of 1.3 m, tree height, Kraft class, condition category, selection category, the presence of faults and damages, were determined for the trees during the study. Average annual increments by diameter and height as well as growth rate were defined. Integrated assessment of introduction success was carried out by scales (Wysotska 2013, Los, 2012, Grybovich, 2018) with refinements. Data were processed using MS Excel and R-statistics software.
Results
The maximum exceeding of the average indicators of all observed stands in diameter was characteristic for plantations at the arboretum on the territory of nursery in Kharkiv National Agrarian University (24.2 % of average and 90.8 % of the table indexes of English oak), and in height, for the plantations in quarter VII in Kharkiv National Agrarian University arboretum (35%). The height increments were quite close and ranged from 0.36 to 0.44 m, while increments in diameter were from 0.54 to 0.99 cm.
The highest values of the increments, both by height and diameter, were noted for trees in the nursery area. According to the selection structure evaluation, most plantations had a high proportion of trees of the 1st and 2nd selection categories of above 20 %. The group of trees located in the nursery of Kharkiv National Agrarian University had the best selection structure; here, the proportion of trees of the 1st and 2nd selection categories was 46.2 %. The trees of Turkish hazelnut in the Veterans’ Park have the best condition. In all the surveyed plots, the trees produced viable seeds and seedlings and had a high degree of acclimatization in the Kharkov region. According to the integrated assessment, three of the five observed Turkish hazelnut stands were found to be promising by a combination of characteristics. In terms of selection, the most valuable was the Turkish hazelnut stand in the nursery of Kharkiv National Agrarian University.
Conclusions
The Turkish hazelnut has adapted well to the Kharkiv region, showing high growth rates. The observed Turkish hazelnut stands had a high proportion of trees of the 1st and 2nd selection categories and by this indicator, in most cases, met the requirements of plus stands. According to the results of the integrated assessment, most of the stands are considered as promising, i. e, suitable for forest planting, protective stands creation, and landscaping.
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