Site classification vs. wood production: A case study based on silver fir growth dynamics in the western carpathians

Abstract

We analysed wood production on an example of Silver fir growth ability within site units defined in the site classification that is currently used in the Western Carpathians. It has arisen as a very important issue, since the site units have been widely used in forestry practice and, moreover, it represents one of the input variables of growth model. Research plots established for development of a yield model for Silver fir in the sixties were used. The Korf growth equation was used to model the Silver fir growth, since it showed the best fit to the data compared to other equations. The test of residual variance of the growth models and the test of regression coefficients of the growth models were employed to investigate the differences in top-height growth of Silver fir occurring on different sites. Results showed a very high variability of the top height development within the site units. Nevertheless, two main groups of sites being different from each other were recognized. But, significant differences in the height growth of fir between site units were found mainly in mature stands starting at the age of 60, which could be due to different soil depth and nutrient regime. Lastly, discussions about the approaches to site classifications all over the world showed many alternatives used to develop a classification scheme with different and in many cases unknown precision, and thus there is a need for the objectivity of classification.