Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Long-term research program carried out on permanent experimental plots allowed to develop a local site index model of unthinned Scots pine stands (PINUS). On the basis of appropriately selected, in terms of quantity and quality of empirical material and grouping stands with similar growth rates, the best equations of regression were selected. The final choice of functions and algorithms was guided by the size of the coefficients of determination and secondary error rates. Using the model is user-friendly because it functions in an EXCEL electronic environment. Adequate bonitations were set according to the average height or the top height of a certain age, using a table of valuation (BON) or the charts of average height (WH) and of the top height (WHg). The spreadsheet BON cell type X set age stand was used. Then, the average height (H) or top height (Hg) were defined comparing the displayed data in row X and the best suited bonitations were selected. Then the appropriate sheet: B24-B34 was chosen, and the prescribed age is entered into the X cell. At the command line, X and above, characteristics of age X and age X-5 are seen. All features can be accessed directly from the tables: B24-B34, in the 5-year age range from 20 to 120 years. The developed growth model can be used to estimate overground biomass and carbon sequestration of unthinned Scots pine stands for the bonitations: BON24-BON34, in the Forest Experimental Station Murowana Goślina. For the regional application of the PINUS model it is necessary to analyse its accuracy in other Polish regions and possible corrections constant of factors equations. In the future it is also planned to supplement the model on the weaker bonitations by extending the scope of research in regions where such stands grow.