Effects of Differences in Light Environment on the Growth and Survival of Planted Quercus serrata Seedlings

• Published in: Journal of the Japanese Forest Society Vol. 106; no. 8; pp. 215 - 224
• Main Author: Nakajima, Haruki
• Format: Journal Article
• Language: Japanese
• Published: The Japanese Forest Society 28.12.2024; 一般社団法人 日本森林学会
• Subjects: accidental cutting; die-back; diffuse transmittance; hardwood plantation; retention harvesting; 保残伐; 先枯れ; 広葉樹人工林; 散乱光透過率; 誤伐
• ISSN: 1349-8509; 1882-398X; 1882-398X
• DOI: 10.4005/jjfs.106.215

Planted Quercus serrata seedlings in oak forests, previously affected by Japanese oak wilt or subject to retention harvesting, experience diverse light conditions due to the presence of retention trees. To elucidate the effects of differences in light environment on the growth of planted Q. serrata, a survey was conducted five years after planting across 22 plantations (3 clearcut and 19 retention harvesting sites) in Toyama Prefecture, Japan. Two study plots were established at each plantation, with weeding conducted annually. Diffuse transmittance (DT) across plots varied widely from 5％ to 94％, corresponding to the amount of retention trees. Reduction in planted tree height due to die-back occurred frequently in dark environments. Based on the model equation, tree height growth was impeded at DT below 24％, and survival rates decreased to less than 66.6％ at DT below 16％, thus rendering such dark environments unsuitable for planting. Tree height was greater in brighter environments, whereas survival rates were higher in medium-light environments with approximately 50％ DT. A thorough investigation of the four plots revealed that brighter environments caused more abundant competing vegetation and higher accidental cutting ratio (up to 50％), suggesting that these were factors for decline in survival rates in bright environments. In medium-light environments, tree height growth was slow, but survival rate remained heigh; therefore, artificial regeneration of Q. serrata will likely be successful.