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ABSTRACT
Diameter distributions of stand modeling play an important role in forest growth, yield, management, and CO2 fixation. The objective of this study was to describe the parameter predictions of a Weibull model for diameter distribution over 100 years in a pure, even-aged stand of Cryptomeria japonica in Taiwan. Decreasing stand density was influenced by the thinning and typhoon event. The stand height increased with increasing stand age until 45 years, after which stand height remained at 28 ± 0.5 m until 103 years of age, indicating that it had not experienced a typhoon with sustained strong winds causing the trees to lose their tops but survive. The 3D dynamic curve of stand structure was compared with a traditional 2D curve to demonstrate the interrelation between the diameter at breast height (DBH), frequency or tree number, and stand age. The parameters a, b, and c showed that the Weibull distribution moved to the right, the peak intensity of the curve moved toward the right and became weaker and broader with increasing stand age. The DBH curve effectively changed after the thinning treatment with different variation trends for the three Weibull parameters. The Weibull model would facilitate future research to provide a wealth of information on forest management and the estimation of stand wind damage.
Acknowledgements
This paper, we dedicate to older generations for their vision of studying long-term experiment plots. Data analyzed in this paper were collected by Experimental Forest, National Taiwan University. The authors appreciate the assistance in providing data by the institutes and individuals aforementioned.
Disclosure statement
No potential conflict of interest was reported by the authors.