The protective afforestation in Steppe is one of the priorities of the forest branch. With the implementation of the state policy in the field of protective afforestation experience gained in Velykoanadolsky forestry is actual and rewarding. Yield tables are the basis for regulatory and reference data in forest management, accounting of forests and forest resources. Most of existing yield tables was developed primarily for normal stands. Such tables do not take into account regional characteristics of growth and state of forest plantations. The aim of the study is to determine the characteristics and to comparethe course of growth and productivity of artificial oak stands of the Velykoanadolsky forest area.
Materials and Methods
To determine the characteristics of growth and formation of modal stands and to develop yield tables, data of Forest inventory Database of Production Association “Ukrderzhlisproekt” were analyzed using conventional techniques, as well as the data of 60 plots and indices of 30 sample trees. As standard the indices of high-yield stands of the Velykoanadolsky forest area with relative stand density of more than 0.80 were used.
Creating of the Velykoanadolsky forest included gradually increase of forest areas and works on correcting and replacing dead plants. Since XX century afforestation and reforestation mainly aimed at forming of oak stands. Today forest resources of the Velykoanadolsky forest area are represented by stands of 20 forest forming species among which oak stands are dominating. Their share is 86 % of the forest covered area. The main part of oak stands (84 %) is growing in fresh elm-maple oakery conditions. Almost all stands of the forest area are simple in structure, which does not meet the standard for steppe forest.
The average height of the stand is an important inventory index to establish a course of growth. The Mitscherlich’s function serves as a baseline to simulate the height. It is widely used for the simulation of the processes of forest stands growth and takes into account the biological characteristics of oak growth most thoroughly. Growth in height of modal stands is within the II site class ин M. M. Orlov’s site quality scale. Growth in height of standard stands is within the I class. By the ratio of mean and current annual increments in yield tables the age of quantitative maturity of modal stands was identified.
The established mathematical equations quite accurately characterize the s course of growth of artificial modal oak stands of the Velykoanadolsky forest area. They were used to form the yield tables of modal and standard oak stands. Standard artificial oak stands of the Velykoanadolsky forest area are inferior in productivity to dense artificial oak stands at 15–40 % and exceed by 5-25 % the native forest stands in fresh elm-maple oak forest (according to I. V. Turkevich).
Age of quantitative maturity of stands in adverse site conditions including arid climate of Ukrainian Steppe increases compared to the optimal site conditions. Due to the protective and environmental functions performed by plantations of the Velykoanadolsky forest area, the age of maturity for them should be estimated on ecological and biological basis. Forest protective properties begin to appear maximally in middle-aged stands and end by 1–2 age classes to the natural maturity. Thus, growing of plantations to the age of natural maturity in the Steppe is not always efficient from an environmental point of view.
Oak forest stands of the Velykoanadolsky forest area are represented mostly by artificial, even-aged, mixed in composition and simple in form stands of II–III site class, growing in fresh elm-maple oak forest. Age of quantitative maturity of modal stands, defined by an increment, is 75 years old. It is higher than the age of quantitative maturity calculated by the change in standing volume (70 years), which is scientifically justified. Developed yield tables objectively characterize the dynamics, taking into account regional peculiarities of growth and formation of mixed modal oak stands of the Velykoanadolsky forest area. The yield tables of modal stands should be used when planning the volumes of intermediate use. The yield tables of standard stands should be used for grounding modes of stands cultivation.