In order to examine the seasonal changes in the colonization rates of arbuscular mycorrhizal (AM) fungi in the roots of Cryptomeria japonica, we collected roots from mature trees and seedlings in Takakuma Experimental Forest of Kagoshima University from January 2012 to November 2013. We stained sample fine root segments and observed AM fungi by microscopy. As a result, all the individuals of C. japonica examined in this study were colonized by AM fungi. Colonization rates were low from January to May for both mature trees and seedlings. They drastically increased in June and then decreased until August. They recovered after summer from September till November for mature trees and till October for seedlings, and decreased again. Colonization rates showed quite similar patterns of seasonal change between the two years both for mature trees and seedlings, but were generally higher in mature trees than in seedlings. Colonization rates showed significant positive correlation with mean air temperature in total, but more precisely, they increased with the increase in temperature below 22℃, but decreased above that temperature. Precipitation also showed significant positive correlation with colonization rates, but this seem to be an indirect relationship reflecting the relationship between colonization rate and air temperature.

We investigated the genetics structure of Rhizopogon roseolus by using microsatellite markers (SSR, Simple sequence repeat) in three geographical scales: fine-scale, local scale and national scale. Fine-scale genetic structure analyses revealed genet size of R. roseolus is small (Avg. 0.6 m, ≦1.6 m) and genet turnover is frequent (95.8％ within 1 year), indicating R. roseolus depends on frequent sexual reproduction. Spatial autocorrelation analyses detected significantly positive genetic structure in the shortest distance class (0‒4 m), within which dense spore mass is directly dispersed into soil from melted sporocarps after maturity. Local scale analyses in Tottori Prefecture revealed that R. roseolus populations in the Tottori sand dune had higher genetic diversity than those of outside, and gene flow between the outside and inside of the dune was restricted in this spatial scale (e.g. F_ST＝0.243 for 32.2 km). STRUCTURE analyses were conducted in R. roseolus strains from 21 regions in Japan and found 4 genetic clusters corresponding to the geographical origins of the strains. Our results indicate that restricted gene flow of R. roseolus causes genetic differentiation between regional populations. Unique genetic variations among differentiated populations could be useful resources for R. roseolus breeding.

This study investigated the effect of a shortened weeding period on colonization by native broad-leaved tree species over 8 years from the age of 4 to 11 in a plantation of hinoki cypress. The weeding period was experimentally reduced to 3 years in a part of the plantation, which was compared with another part where the weeding period was the standard 6 years. At the end of the study, saplings of wind- and bird-dispersed trees (e.g., Fraxinus, Prunus) were found in both parts of the plantation, but no gravity-dispersed trees (e.g., Quercus) were found. At the age of 11 years, the planted trees were much taller than the colonizing trees in the 6-year weeding area. By contrast, in the 3-year weeding area, the colonizing trees were often taller than the planted hinoki cypresses trees, although most of them were shrub species.

In Japan, rural areas have maintained the forests and their public functions, but their activities are gradually declining because of the stagnant forest industry and the depopulation and aging of the society. In recent years, project-based learning (PBL) on regional issues or problems has been introduced in higher education, and there are increasing cases of applying forests as regional resources. This study measured the ability growth of students in project based learning using 12 competency elements of Fundamental Competencies for Working Persons as an indicator. By comparing ability growth in forest environmental education (FEE) with that of PBL, the growth in their ability by FEE was higher in “stress control,” followed by “creativity” and “ability to influence,” after a year-long activity. Principle Component Analysis was applied in order to validate the factors, and influences by “accomplishment factor by reflection” and “activity content factor” were confirmed. Specifically, the activities of FEE are influencing growth in “ability to grasp situations,” “ability to apply rules and regulations,” and “ability to stress control”.