FOREST COVER PERCENT AND SILVICULTURAL AND MENSURATION PECULIARITIES OF THE STANDS IN THE RIVER CATCHMENTS IN THE LEFT-BANK FOREST STEPPE

Abstract

Introduction

According to their purpose and location, the forests of the Left-bank Forest Steppe perform water-regulating and protective, recreational, aesthetic, educative and other functions. The forests have a positive influence on the climate of the territory and soil and water resources; they significantly reduce the negative impact of water and wind erosion and are a source of forest products.

The purpose of the research was to determine the silvicultural and mensuration indicators of forest stands on the watersheds of the Left-bank Forest Steppe, Ukraine.

Materials and Methods

To demarcate the boundaries of the catchment areas for the Sula, Psel, Vorskla and Siversky Donets rivers, MapInfo Professional 12.5 software and a vector map of Ukraine were used.

Classification of river catchments by the percentage of areas covered with forest vegetation was undertaken according to the method of Hrodzynskyi (1993).

To identify the efficiency of forest site capacity used by oak and pine stands in the most common forest types, we used methods of forest typological analysis.

Results

In the territory of the Left-bank Forest-Steppe zone, the following numbers of water catchments were demarcated for the rivers: Sula – 36, Psel – 35, Vorskla – 24, and Siversky Donets – 23. In total, 118 catchment areas were defined.

The calculations showed the following: 51 catchments belong to low forested areas; 46 catchments belong to almost non-forested lands; 10 catchments are medium forested and 9 catchment areas are non-forested. The number of relatively forested catchment areas was the smallest, two only.

The age structure of forests in the studied river catchments was unbalanced. To compare the age structure of tree stands, they were conventionally combined into groups of age classes, 4 age classes in each group. Stands of the 5^th–8^th and 9^th–12^th age classes prevailed; their percentages of the total area of forest vegetation were from 48 to 62 % and from 20 to 38 % respectively. Tree stands of the 1^st–4^th age classes occupied from 10 to 18 %. The insignificant areas were covered by the stands of the13^th and higher age classes, only from 1 to 4 %.

Recreational and protective forests dominated in the catchments of the Left-Bank Forest Steppe, with an area of 37 and 36 % respectively. The proportion of forests for main use was 29 %. Protective forests prevailed in the water catchment areas of Sula (44 %), Psel (47 %) and Vorskla (48 %) rivers. They covered only 18 % of the forested areas in the catchment of the Siversky Donets River.

In the region of the research, the most common types of forest were fresh maple-lime fertile oak site type and fresh oak-pine fairly infertile pine site type, which were 46 % and 17 % respectively. Based on this, the average mensuration characteristics and the extent of the forest site capacity use were calculated for oak and pine stands for these types of forest.

Conclusions

In the Left-bank Forest-Steppe zone of Ukraine, the river catchments include a significant part of the catchments of the lower-order streams. The last have low forest cover, the level of which is considerably below the limit of the established optimal forest cover percent for water conservation. At such water catchments, the growing new forests to achieve the optimal percent of water protection forest cover must be a priority.

There was a significantly unbalanced distribution by age classes of the stands on the river catchments: stands of the 5^th–8^th and 9^th–12^th age classes prevailed; the proportion of stands of the 1^st–4^th age classes was insignificant. Therefore, the forest age imbalance should be narrowed by a set of activities in the catchment areas of the rivers.

5 Fig., 8 Tables, 17 Refs.