The research is relevant as it is necessary to study the growth and productivity patterns characteristic of European aspen in the most common edatopes in different natural and climatic conditions of the plain part of Ukraine. Improvement and updating of mensuration standards, taking into account the forest site conditions, will help researchers to solve urgent problems as in the current inventory of European aspen stands, so in forecasting the dynamics of their growth.
The aim of the study was to model the aspen stands yield in fresh and wet fertile sites, as well as to compare the aspen stands productivity in different natural and climatic zones.
Materials and Methods
To build the yield tables, we used the subcompartment database of Ukrderzhlisproekt Production Association. We analyzed 2450 subcompartments in European aspen stands. Data processing was carried out in accordance with generally accepted in forestry and forest mensuration procedures and mathematical statistics methods.
The total area of European aspen stands in the plain forests subordinated to the State Forest Agency is 34.3 thousand hectares. The main part of European aspen forests grows in Polissia and Forest-Steppe (47% and 46% respectively), and only 7% – in Steppe. At that, European aspen stands of coppice origin dominate. They cover 86–93% of the total area depending on the natural zone.
In Ukraine, European aspen stands are mostly concentrated in fresh and moist fairly fertile sites and fertile sites. Thus, in fresh and moist fairly fertile sites they make 55% in Polissia, 37% – in Forest-Steppe and 13% – in Steppe. The 1st productivity class stands dominate in Polissia and Forest-Steppe. Their area is 44% and 43%, respectively. In Steppe, dominating stands are those of the 2nd productivity class. They occupy 39% of the territory
We obtained mathematical correlations that characterize the growth of European aspen stands of coppice origin in fresh and moist fairly fertile site conditions and prepared a draft of the yield tables. The stock volume of modal European aspen stands in Polissia is 4–34% higher than the corresponding values given in the literature for trees up to 30–35 years old. According to our data, since the age of 40, the stock volume of stands is less than that given in other works. At that, the difference increases with age from 5 to 30%.
The age of quantitative maturity of modal European aspen stands of coppice origin was determined by stock change. It is nearly the same in all studied natural zones and is 25–28 years.
We came to the conclusion that the aspen stands are concentrated in Polissia and Forest-Steppe. At that, they are mainly represented by coppice origin stands of 1st productivity class which grow in the fresh and moist fairly fertile and fertile site conditions. In Forest-Steppe and Steppe, European aspen stands are mainly concentrated in the Left-Bank Ukraine, and in Polissia – in both parts of Ukraine.
The yield tables developed within the research accurately characterize the growth and formation feature of modal European aspen stands of coppice origin in the plain part of Ukraine. Therefore, they can be applied when planning intermediate felling volume. Moreover, the determined quantitative maturity age should be taken into account when justifying and clarifying the maturity age of aspen stands.
4 Figs., 5 Tables, 14 Refs.