Model Development for Thinning Effect Analysis (I)
Son, Yeong-Mo, Lee, Kyeong-Hak, Seo, Jeong-Ho and Lee, Woo-Kyun

 

Abstract : In this study, the development of stand mean DBH (change of mean stand DBH accoring to the thinning), especially the thinning effect on 8 tree species was analyzed using the DBH distribution model and dynamic stand growth model. To analyze the thinning effect using DBH distribution model, Weibull distribution function which is used widely was applied. At the analysis process, mean DBH that controls the form of distribution, minimum DBH or minimum DBH class, maximum DBH or maximum DBH class, standard deviation of DBH and stem number per ha were used basically. To estimate the change of variables mentioned above after thinning, thinning distribution index(K) was developed and regression equations which contain thinning distribution index(K) as an independent variable were prepared and the thinning effect was analyzed using prepared equations. Each variable of prepared equations was significant and the prepared equations were also significnat to estimate the change of stand mean DBH. The estimation of change of stand mean DBH after thinning proved that the tendency of stand development was coincided with general growth principles and this method was considered as adequate for analyzing thinning effect.
To analyze the thinning effect using dynamic stand growth model, regression equations that estimate change of stand after thinning using thinning intensities, stand mean DBH before thinning and thinning index were derived. After the derivation, the equation that estimates the stand mean DBH was derived. The derived equation could be re-arranged to give the new equation, that is the algebraic difference form of original equation, to estimate the change of stand mean DBH until next thinning period. The estimation of change of stand mean DBH after thinning using different thinning intensities and stand densities proved also that the tendency of stand development was
coincided with general growth principles and this method was considered as adequate for analyzing thinning effect.
In practice, therefore, both algorithms can be applied for analyzing and estimating the development or change of stand for various forest treatments especially for various thinning conditions. Furthermore they can be used by the tool for decision-making in forest management plan.

 

Key words : thinning, distribution index, dynamic stand growth model