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Abstract
Introduction
The study of the biological productivity, ecological and energy potential of the forest stands involves the evaluation of the qualitative features of the trees’ phytomass, which are determined by genetic programs of the plant organism and the influence of the abiotic and biotic factors.
The goal of this research was to establish values of average natural wood density of black locust trunk in the forest plantations within Northern Steppe of Ukraine.
Materials and Methods
In the study, the indexes of the average natural density of trunk wood, bark, and trunk wood in the bark of black locust trees were determined. The dependence of the parameters from the main biometric characteristics of sample trees such as age, DBH, and height of the trees was found.
Investigation of trunk wood density of black locust was carried according to P. I. Lakida’s procedure. In the course of the investigation, 20 sample trees were cut and measured, biometric indicators of the plantations in which they grew were determined and 180 wood samples were analyzed. Test trees age was from 3 to 89 years.
Results and Conclusions
The values of the average natural density of the trunk phytomass components of black locust sample trees had a variance about trend lines, which characterize the wood density dependence from biometric indicators of the trees.
The natural wood density is characterized by an increasing type with age, DBH, and height of the sample trees. The maximum value of the average natural wood density was 921 kg (m?)-1 and corresponded to a sample tree from the overmature age group, aged 38, with DBH of 16.0 cm and height of 15.7 m. The minimum value of this indicator was recorded for the three-year tree with DBH of 4.5 cm and height of 5.8 m.
The average natural bark density had a significant dispersion. The difference between the maximum absolute value of the natural bark density (633 kg·(m?)-1) for the 10-year-old sample tree with DBH of 6.2 cm and height of 6.4 m and the minimum value (387 kg·(m?)-1) for the 43-year old sample tree with DBH of 19,6 cm and height of 13.4 m was 61.1%. Particularly, the trend for a significant dispersion of natural bark density was observed for the trees from young age group. In general, tends for the natural bark density to decrease with age, DBH and height of sample trees were detected.
Trend lines for the dependence of the average natural density of wood in the bark from the mensuration parameters of the black locust sample trees were found to increase.
Taking into account the sufficient homogeneity of the experimental data regarding site index and type of forest conditions, a search of mathematical models for estimating the average natural density depending on biometric parameters of the sample trees has been carried out on the basis of the obtained data. It was not possible to obtain positive results for mathematical models estimating the dependence of the average bark density on age, DBH, and height of the sample trees.
For the average natural density, a significant variability of the indicators was recorded. It is consistent with the results of other researchers, who noted a significant variance for these values for forest-forming species such as Populus tremula L., Fraxinus excelsior L., Alnus glutinosa (L.) Gberth.
The indices of the average natural density of black locust trunks in the Northern Steppe of Ukraine cannot be compared with the data for this forest-forming species that grows in other natural zones of Ukraine due to the lack of such studies.
The revealed peculiarities of the studied indicators of natural density of the black locust trunks can be taken into account in determining the dynamics of above-ground phytomass, in calculations of the carbon volumes deposited by black locust plantings and in the development of activities aimed at regulating the ecological functions of forests in the Steppe zone of Ukraine.
3 Figs., 3 Tables, 14 Refs.