The regional forests are mainly represented by stands of Quercus robur L., the area of which makes up 46.4 % (284.1 thousand hectares) of lands covered by forest vegetation (611.9 thousand hectares). The oak forests are predominantly commercial (34 % of the area), protective (28 %) and recreational (26 %), most of them are of vegetative origin (57.3 %) and planted forests (35.7 %). The natural pedunculate oak stands of seed origin cover only 7 %. The age distribution in oak forests of the region is unbalanced. Stands of age classes from 7th to 10th prevail with an area percentage of 63.5 %. The increase in mature and overmature oak stands results in a weakening of their protective functions. This is particularly true for noncommercial forests. Therefore, the issue of regenerating valuable natural oak forests through the reconstruction of oak coppice forests into seed ones is relevant.
The aim of the research was to determine the best ways and technologies for reconstruction of noncommercial weakened coppice oak stands to enhance their benefits.
Materials and Methods
The research of the stage-by-stage reconstruction of a noncommercial weakened oak coppice stand was started in 2008. The experiment was established in the southern part of Left-bank Forest-Steppe zone of Ukraine in the fresh fairly fertile maple-lime oak forest type, in the recreational forest of the Pivdenne forestry, Kharkiv Forest Research Station.
During the study, the new findings were obtained that can be applied in the reconstruction of the noncommercial weakened coppice oak stands. For the first time, we propose the technology for reconstruction of coppice stands into mixed seed natural or planted ones, using regeneration felling with the elements of even gradual, group successive and strip gradual felling with a continuous cutting of 25 m width strips. The use of the technologies that combine regeneration felling, selective sanitary felling and thinning in conjunction with silvicultural activities will allow to form mixed seed natural or planted stands of different ages from noncommercial weakened coppice oak forests and significantly increase their productivity and sustainability.
Regeneration felling in weakened oak coppice stands should begin in the year of good oak harvest in an autumn-winter period, followed by acorn fall and after activities promoting natural regeneration, such as loosening of soil and forest litter, removing undergrowth and weakened trees, and leaving “seed trees”.
Regeneration felling with even gradual and strip gradual elements, combined with promoting natural regeneration in weakened oak coppice stands positively influenced the natural oak reproduction, which was more than 6 thousand stems per hectare at the age of 4–8.
Among the experimental variants of the oak stand reconstruction, including regeneration felling combined with cultivated reproduction, the best average height and diameter were registered in the variant with strip gradual method of regeneration felling followed by creating forest plantations by planting one-year-old containerized oak seedlings on the cutting areas.
2 Figs., 4 Tables, 14 Refs.