Growth characteristics and growth equations of the diameter at breast height using tree ring measurements of street trees in Kyoto City, Japan

Abstract

Tree growth equations are indispensable for modeling tree functions for ecosystem services. However, knowledge about the growth rates of street trees in Japan remains limited. This study aimed to examine the growth characteristics of street trees (Zelkova serrata, Platanus orientalis, and Prunus yedoensis) in Japan to generate growth equations of the diameter at breast height (DBH) based on measurements of tree rings. Specifically, diameter growth was used and compared against nursery-grown trees used in previous studies in Japan and street trees in the USA. The diameter growth rate per year of Z. serrata ranged from 0.43 cm to 1.12 cm, with peak growth occurring at 17.8 years of age. For P. orientalis, the diameter growth rate per year ranged from 0.25 cm to 1.59 cm, with peak growth occurring at 7.4 years of age. For P. yedoensis, the diameter growth rate per year ranged from 0.68 cm to 1.65 cm, with no apparent peak growth. The Chapman-Richards growth function generated the best fit as a diameter growth equation for all three species out of three tested theoretical growth equations (Chapman-Richards, Gompertz, and Logistic function). For 25-year old trees, the estimated DBH of Z. serrata and P. orientalis grown as street trees was 68 % and 84 % of that of nursery-grown trees, respectively. For street trees 25 years after planting, the estimated DBH of Z. serrata, P. orientalis, and P. yedoensis in Kyoto City was 62 %, 63 %, and 56 % of that of street trees in the USA. The diameter growth of street trees in Kyoto was substantially lower than that of nursery-grown trees and street trees in the USA. Therefore, region-specific growth equations must be developed for street trees when the planting environment and management approaches are different.