Sustainability of High-Value Timber Species in Mixed Conifer–Broadleaf Forest Managed under Selection System in Northern Japan

Abstract

Understanding the sustainability of high-value timber species in managed forests provides useful information for the management of these species in the long-run. Using nearly 50 years of census data in long-term permanent plots, we investigated the sustainability of three high-value timber species—monarch birch (Betula maximowicziana Regel), castor aralia (Kalopanax septemlobus (Thunb.) Koidz), and Japanese oak (Quercus crispula Blume)—in cool-temperate mixed forest under a selection system in northern Japan. We used stocking, demographic parameters, and species proportions of these species as measures of sustainability. Results showed that the tree density and basal area of the three high-value timber species increased during the study period. Moreover, the basal area increment of these species showed an increasing trend across census periods. However, while no significant differences in the tree mortality of these species were observed, the numbers of in-growth fluctuated across census periods. Increasing trends in species proportions of monarch birch and Japanese oak were observed. Even though there were some fluctuations across census periods, especially in smaller diameter classes, diameter distribution curves of high-value timber species followed a reversed J-shaped pattern. The results revealed that the sustainability measures of high-value timber species can be achieved in forest stands managed under single-tree selection system. In addition, the results also indicated the changing structure and composition of the forest stand. The stocking and basal area increment of conifers decreased while those of broadleaves increased. The proportion of conifers decreased to 33.01% in 2008–2016 from 48.35% in 1968–1978. The results of this study would be useful for adapting silvicultural practices and harvesting practices as well as for simulating various silvicultural and management options for high-value timber species.

Predicting individual tree growth of high-value timber species in mixed conifer-broadleaf forests in northern Japan using long-term forest measurement data

“…We divided the study period of 48 years into five intervals with approximately 10 years in each interval. We found that small number of trees and BA of high-value timber species were harvested, and more conifer BA were harvested than broadleaf BA (Moe and Owari 2020). The removal of trees by selection harvest may affect the growth of remaining trees.…”

“…Attention was paid to be spatially unbiassed when marking trees for selection harvest and larger trees are more likely to be marked than smaller ones while dominant species, i.e., A. sachalinensis, is more likely to be marked (Owari et al 2010). In our previous study (Moe and Owari 2020), we analyzed the BA harvest of high-value timber species, conifer, and broadleaf species. We divided the study period of 48 years into five intervals with approximately 10 years in each interval.…”

Changes in the Market of Precious Wood: A Case Study of Submission System in Poland

“…The management of rare species, which often play a biocenotic role in the forest and increase biodiversity, has a significant impact on the economic benefits of forest owners [31]. Increased revenues from the sale of rare or less popular species found in forests may balance, and sometimes exceed the costs of, complications resulting from the increased labor-intensity of caring for and obtaining wood raw material from such forests [32,33].…”

Mapping the Distribution of High-Value Broadleaf Tree Crowns through Unmanned Aerial Vehicle Image Analysis Using Deep Learning

“…High-value tree species are economically important [1,2] as they are used in various industries, support local economies, and are the basis of valuable products for domestic and international markets. Moreover, they play a central role in ecosystem functioning, by supporting biodiversity (such as through the provision of habitat and food resources) and providing essential ecosystem services, and in ecological interactions that help maintain ecological balance and sustainability [3].…”

“…Thus, the present study explored the applicability of high-resolution UAV imagery and the ResU-Net model (U-Net model with ResNet101, pre-trained on large ImageNet datasets, as backbone) to predict the distribution of a high-value deciduous broadleaf tree crowns in an uneven-aged mixed forest located at the University of Tokyo Hokkaido Forest (UTHF). Specifically, because Japanese oak is not only a high-value timber species of northern Japanese mixed forests but also a dominant tree species in the UTHF [1], it was selected for our individual tree segmentation task. In addition, we used UAV images taken before and after the color change of Japanese oak leaves to determine the optimal timing of UAV image collection for integration with the ResU-Net model.…”