DBH growth model for Pinus densiflora and Quercus variabilis mixed forests in central Korea

This study presents an individual tree diameter at breast height (dbh) growth model for mixed Pinus densiflora (Red pine) and Quercus variabilis (Oak) uneven-aged stands in central region of Korean peninsula. The different model components, including the effects of tree age, tree size, competition and growing site are evaluated for both Red pine and Oak. The aim is to understand and model the individual growth patterns of the two species. Based on sensitivity analysis of radial growth using a variety of combinations of independent variables, the conclusion could be reached that the size and aspect components have a positive effect on radial growth, while the other variables such as age, competition index, elevation, and slope have a negative influence. All model component effects, except the effect of elevation, are greater in pine than in Oak, indicating that Red pine is relatively less suppressed than Oak in the study area. Among the topographic variables, slope appears to be an important critical factor for Red pine. For Oak, elevation is the primary critical factor and other variables have no great effect. These interrelationships between radial growth and the age, size, competition, and site variables correspond quite well with ecological expectations and silvicultural experience of the two species in Korea.