Crown forms of scots pine (Pinus silvestris L.) in pure high-density plantations of the Minusinsk basin of Krasnoyarsk krai

Abstract

In order to clarify some silvicultural issues concerning the different forest forms and different caring methods, it is necessary to know the dimensions of the tree crowns (length, cross-section, volume, lateral area). Methods for determining these elements have not yet been sufficiently developed. The object of our study was a relatively homogeneous isolated forest area, in which pine trees grow. The main objective of our work was to determine crown forms of Pinus sylvestris in various sizes and to estimate their volume. According to silvicultural zoning, the study area belonged to the Altai-Sayan mountain taiga region of the silvicultural province of pine and fir forests (Sisimsky District of mountain taiga fir and pine forests).

Studying the range of crown forms of Pinus sylvestris, it is possible to distinguish several groups of predominance of one or another form. In steps of 8 and 12 cm in thickness, the cylindrical form has the greatest prevalence, with a slanting cone being rare. The presence of this form can be explained by not yet closed canopy, with climatic factors having a favourable effect on crown development and absence of clear competition. It is difficult to identify the predominance of any one form in steps 28 and 32. In this case the form depends on stand completeness, availability of light and competition. Lack of light, high stand density and species competition contribute to the formation of different crown forms.

As a result of the performed work, it has been determined that it is not possible to compare the crowns with any particular geometric figure, as the crown habitus is diverse. This variation in thickness indicates that the pine crowns are very vulnerable to wind loads. It is not possible to propose one universal formula for determining the form of pine crowns, as volume errors are significant. The volume of pine crowns is recommended to be determined separately for large and small trees.