DBH-Height Relationship for Japanese Red Pine (Pinus densiflora) in Extensive Natural Forests in Southern Japan

The diameter at breast height (DBH)-tree height relationship for Japanese red pine (Pinus densiflora) in an extensive natural forest (27.86ha) was studied at the Kyushu University Forest in Miyazaki (UFM), southern Japan. DBH-height allometry and the shape of height distribution based on DBH class were analyzed using a generalized allometric equation and the Weibull distribution function, respectively, and a height estimation model based on DBH (HEMD) was constructed. The slope of the DBH-mean height curve at a forest level was steeper than that for Pinus densiflora stands at a plot level. The height distributions based on DBH class were positively-skewed and the degree of skewness was stronger at sizes <20cm and >50cm. HEMD described height distribution and DBH class-volume distribution well at a forest level. The effects of stand structure on size diversity and the DBH-height relationship of Pinus densiflora in the UFM were discussed.