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Abstract
Introduction
The introduction of new, not typical for a particular region tree species in forest stands is an important issue contributing to greatly increase productivity, quality, and ecological effectiveness of forests. The efficient use of promising introduced species for reforestation and afforestation can provide a high adaptive capacity of forest plantations to changing environmental conditions, corresponding to forest ecosystems with a wide range of economic, social and environmental functions.
The introduction of valuable forest species can be applied into forest plantations as an addition to the usual assortment of tree species growing in a certain region that will provide increasing of biodiversity and productivity of forests and of their ecological role.
The aim of the research was to analyze the diversity of the species composition of introduced trees in the forest stands in the State Enterprise “Lubny Forest Economy” and to assess the sustainability and decorativeness of the tree stands of introduced species.
Materials and Methods
Typical forest stands were surveyed, by selection of forest management materials and the creation of 188 test plots in forest stands of the enterprise in which the share of introduced species was at least 10 %.
For estimation of introduced plants’ stability at forest plantations, the following indices were evaluated for the enterprise: winter hardiness, drought tolerance, the degree of insect damage and disease damage that may limit the appearance of potential biological features of the species when introducing, flowering and fruiting. At the same time, for assessing winter resistance, drought resistance, insect damage and disease we used scales defined in the method of variety testing of forest tree species in Ukraine by performing some transformations from a 9-point scale into a 5-point one.
Results and Conclusions
The introduced tree species have characteristics of flowering and fruiting, resistance to climatic conditions, diseases and pests at the same level as indigenous tree species, and sometimes even higher. Most introduced species are no less resistant to growth conditions than native ones. In particular, apricot (Armeniaca vulgaris Lam.) is more drought-tolerant than common pear (Pyrus communis L.) and crab apple (Malus sylvestris Mill.) and ash-leafed maple (Acer neg?ndo L.) is compared to Norway maple (Acer platanoides L.). However, Norway spruce (P?cea ?bies L.)is less resistant than Scots pine (Pinus sylvestris L.) and green ash (Fraxinus viridis Borkh.) is than common ash (Fr?xinus exc?lsior L.).
Indicator “The complex decorativeness” of investigated introduced species varies from 2.88 to 4.41, from adequate to medium. The general indexes of stability and decorativeness of introduced species ranged from 3.27 to 4.49 points, respectively from average to good, depending on the species of the tree plant. Such introduced plants as apricot, cherry plum (Prunus divaricata Led.), red oak (Quercus rubra L.), ash-leafed maple, Norway spruce, Amur cork-tree (Phellodendron amurense Rupr.), common walnut (Juglans regia L.), black walnut (Juglans nigra L.), locust tree (Robinia pseudoacacia L.), green ash, Chinese elm (Ulmus parvifolia Jacq.) can be recommended for forest stands under the conditions of the Left-bank Forest-Steppe of Ukraine. Perspective introduced species for greening in similar climatic conditions of Ukraine are red oak, Norway spruce, Amur cork-tree, common walnut, black walnut, locust tree, and green ash.
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