Abstract
As part of a growth and yield study, the Forestry and Forest Products Research Institute and Regional Forest Offices have conducted long-term monitoring in more than 180 permanent experimental sites installed in national forests all over Japan. The present article reports the time-series growth data of 76 plots at 39 sites of Cryptomeria japonica, Chamaecyparis obtusa, Larix kaempferi, and Abies sachalinensis planted forests and 3 plots at one site of Pinus densiflora natural forest, for which the most recent measurement was conducted between FY2011 and FY2015.
To obtain precise growth data, the trees in each plot were measured in detail: every individual tree was, in principle,
identified by a unique number, and its condition (damaged, thinned, or dead) was recorded; the breast height was permanently marked with paint for measurement of the diameter at the same position at every data collection session; and the heights of all individuals were measured using a hypsometer. Moderate qualitative thinning has been
performed in most plots. Some sites include plots with different planting densities or thinning intensities, including
an unthinned plot. Time-series growth data of these plots were successfully used to construct and verify yield tables, to analyze thinning effects and the long-term growth dynamics of planted forests, and to determine the parameters of several forest growth models, indicating that these experimental sites are useful in terms of valuable data sources. Further well-planned, continuous measurements will enhance the value of the growth data.
