STATISTICAL DISTRIBUTIONS FOR MODELLING STAND STRUCTURE OF NEEM (<em>AZADIRACHTA</em> <em>INDICA</em>) PLANTATIONS

Authors

  • D. M. Nanang

Keywords:

Bivariate distributions, Kolmogorov-Smirnov statistic, northern Ghana, univariate distributions

Abstract

Individual and community plantations of neem (Azadirachta indica) and other exotic tree species were expanded in northern Ghana following the introduction of a Rural Afforestation Programme in 1989. This paper describes a study aimed at assessing the suitability of the univariate (normal, lognormal, Johnson SB and gamma) and bivariate (normal (SNN), lognormal (SLL) and Johnson SB (SBB)) distributions for modelling diameter and height distributions of the neem
plantations. The four univariate and three bivariate distributions were fitted to seven age groups of diameter and height data collected from 120 temporary sample plots. In general, all four univariate distributions provided good fits to both the diameter and height data. However, based on the ranking of the Kolmogorov-Smirnov (KS) statistics between observed and predicted frequencies for each age group, the gamma and lognormal were judged the best for fitting the diameter and height data respectively. For the three bivariate distributions, the SLL gave the best performance in terms of quality of fit to the seven age groups using the KS criterion. Height distributions were indirectly derived from each of the four univariate diameter distributions based on the relationship between diameter and height. However, these indirectly derived height distributions did not satisfactorily describe the observed height frequencies.

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Published

2022-08-23

How to Cite

D. M. Nanang. (2022). STATISTICAL DISTRIBUTIONS FOR MODELLING STAND STRUCTURE OF NEEM (<em>AZADIRACHTA</em> <em>INDICA</em>) PLANTATIONS. Journal of Tropical Forest Science (JTFS), 14(4), 456–473. Retrieved from https://jtfs.frim.gov.my/jtfs/article/view/1303

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