Using the Size Structure Parameters of Stands to As-sess their Current State and Development Prospects

Introduction. The size structure of a stand defines its internal diversity that facilitates sustainable development of a cenopopulation by providing materials for the natural selection of specimens and their targeted artificial selection with regard to their economically important characteristics. The aim of the study is to improve the methods of using the size structure parameters of Scots pine (Pinus sylvestris L.) even-aged stands in order to assess their current state and prospects for further development, as well as to identify cenopopulations valuable in terms of selective breeding. Materials and methods. The source material was collected from 300 permanent and temporary sample plots laid out in the even-aged pure pine stands varying in origin, age, density and growth conditions in the Republic of Mari El. On 17 permanent sample plots, circumference measurements were taken on all numbered trees and the estimation of their current diameter increment was performed periodically, every 5–10 years. The duration of observations at the stationary sites ranged from 10 to 40 years. The digital data obtained were processed on a PC using conventional methods of mathematical statistics. Results. The study determined the limits of variability and the key patterns of change in the values of a number of stand size structure parameters, each having its specific informative significance; relevant scores were developed for evaluating the current state and development prospects of the cenopopulations. The study has shown that a network of stationary sample plots is a reliable basis for gaining new knowledge about regularities in the dynamics of the stand size structure formation. Conclusion. For an adequate assessment of the current state of cenopopulations and determination of prospects for their further development, the values of size structure parameters must always be compared with a reference standard, which can be their values attributable either to regional modal stands or so-called “normal” stands.