Journal of Forest Research

, Volume 11, Issue 5, pp 369–372

Fitting irregular diameter distributions of forest stands by Weibull, modified Weibull, and mixture Weibull models


DOI: 10.1007/s10310-006-0218-7

Cite this article as:
Zhang, L. & Liu, C. J For Res (2006) 11: 369. doi:10.1007/s10310-006-0218-7


Irregular diameter frequency distributions of forest stands include multimodal structure of mixed-species stands, highly skewed and highly irregular shapes of uneven-aged stands, and rotated sigmoid form of old-growth stands. In this study, a traditional two-parameter Weibull model, a modified two-parameter Weibull model, and a finite mixture of two-parameter Weibull models were used to fit four artificial example plots. The model fitting and comparison results indicate that the mixture Weibull model is more flexible to fit various irregular diameter distributions, while the traditional Weibull model fails in every case to adequately describe these frequency distributions. The modified Weibull model is a good choice for fitting the “rotated-sigmoid” diameter distribution of an uneven-aged old-growth stand. However, it may not be sufficient when a diameter frequency distribution is multimodal or highly irregular in shape.

Key words

Diameter frequency distributionWeibull functionFinite mixture modelModel fitting and comparison

Copyright information

© The Japanese Forest Society and Springer-Verlag Tokyo 2006

Authors and Affiliations

  1. 1.Faculty of Forest and Natural Resources ManagementState University of New York College of Environmental Science and ForestrySyracuseUSA
  2. 2.Forintek Canada CorporationSainte-FoyCanada