Comparison of percentile based prediction methods and the Weibull distribution in describing the diameter distribution of heterogeneous Scots pine stands

The goal of this study was to compare percentile based distribution methods and the Weibull distribution method in predicting the stand characteristics of forests with great variability in their diameter distribution. Stand structure characteristics were compared between thinned and unthinned stands dominated by Scots pine. The thinned forests were located in eastern Finland, while the unthinned natural forests were located in Republic of Karelia and Leningrad district, Russian Federation. Each data sets included 49 stands. The diameter distributions were more heterogeneous in the unthinned stands. Most of the thinned stands formed unimodal distributions. Among the unthinned stands, decreasing, multi-modal and irregular forms of diameter distributions were also found. In these data, percentile based distribution methods proved to be considerably more effective in predicting the diameter distribution than the Weibull distribution method. With the percentile based distribution method it was also possible to reproduce considerably varying shapes of diameter distributions. (C) 2000 Elsevier Science B.V. All rights reserved.