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 characteristic s of forests with great variability in their diameter distribution. Stand s tructure characteristics were compared between thinned and unthinned stands dominated by Scots pine. The thinned forests were located in eastern Finla nd, while the unthinned natural forests were located in Republic of Karelia and Leningrad district, Russian Federation. Each data sets included 49 sta nds. The diameter distributions were more heterogeneous in the unthinned stands. Most of the thinned stands formed unimodal distributions. Among the unthin ned stands, decreasing, multi-modal and irregular forms of diameter distrib utions were also found. In these data, percentile based distribution method s proved to be considerably more effective in predicting the diameter distr ibution than the Weibull distribution method. With the percentile based dis tribution method it was also possible to reproduce considerably varying sha pes of diameter distributions. (C) 2000 Elsevier Science B.V. All rights re served.