We measured surface soil (fine soil, gravel, and litter) movement in three types of plantation about 40 years old, namely Japanese cypress (Chamaecyparis obtusa), Japanese cedar (Cryptomeria japonica), and Japanese red pine (Pinus densiflora). All of the stands were growing under the same conditions on a steep slope and differed only in terms of the planted species. We also clarified the differences in surface soil movement among the planted species. Movement of fine soil, gravel, and litter per 1 mm precipitation (i.e. the transport rate) was higher in the C. obtusa stand than in the others. The floors of the C. japonica and P. densiflora stands were almost covered with either litter or undergrowth all year around, whereas on the floor of the C. obtusa stand the cover of undergrowth and litter was poorer. A higher floor cover percentage led to a lower rate of transport of fine soil. Consequently, the C. obtusa stand was characterized by easily lost undergrowth and litter, which in turn influenced surface soil movement. Because of the low litter cover, in C. obtusa stands with poor vegetation cover, control of light conditions by tree thinning and maintenance of undergrowth are needed to minimize surface soil movement.

Many plants carried by human migration and trade have become naturalized and significantly affected local ecosystems. A deciduous tree, Firmiana simplex (Malvaceae), of uncertain origin, grows in warm temperate regions in Japan. We explored anthropogenic influences on the distribution of F. simplex along the coast of the Bungo Channel, eastern Japan, by evaluating the successional sere that the species occupies, historical usage, and local plant names. An old land use map, historical records, local knowledge, and field observations of forest stands indicated that the F. simplex-dominated forest on Kashima, Ainan town, Ehime Prefecture, which was generally perceived as primary forest, was most likely anthropogenically disturbed. The F. simplex in several other localities had an aggregated distribution and grew at disturbed sites. These results imply that the species favors mid-successional forest stands. Trunk fiber had various uses around the mid-20th century in the study region. Interviewees told of planting this species on backyard slopes in Kochi Prefecture, and on mountain slopes in Miyazaki Prefecture. Common local names hera and isaki were recorded in both Kyushu and Shikoku. According to a historical record, Tilia species (Malvaceae), which are also called hera, were brought to the Chugoku region for trunk fiber usage in the early 19th century. This fact and our results suggest that F. simplex was introduced along the coast through the cultural diffusion of fiber usage and is now concentrated around specific villages.

To evaluate the suitability of carrion beetle (Silphidae and coprophagous group of Scarabaeoidea) assemblages collected by a simple method as indicators of forest habitat, a pitfall trap baited with fish meat was set one per site in each of 15 small, different-aged forest stands in 2012 in Kumamoto City. I sampled 7,667 individuals, belonging to 13 species of carrion beetles. My results indicate that species richness, total numbers of beetles, Simpson's diversity indices, and the abundance of six species significantly increased with stand age. The results of indicator species analyses on the three groups along with stand age (1−2 years old forests, young forests, and middle-aged forests) showed that one and seven species had significant indicator values for young forests and middle-aged forests, respectively. Ordination analysis of beetle assemblages by nonmetric multidimensional scaling revealed that coordinates of the three groups along with stand age differed from each other if excluding a coordinate of the young forest group. These results suggest that carrion beetle assemblages collected through simple methods may be superior indicators of forest habitat in a mixed forest composed of small stands, and that assemblages can respond to environmental changes associated with the stand age.

Containerized tree seedlings are expected to exhibit high survivorship and good growth after outplanting; however, a unified consensus on the performance of containerized seedlings in Japan remains undetermined. To understand the universal properties of the performances of containerized seedlings after outplanting, the survival ratio and height and diameter growth rate of two stock types (containerized seedlings and bare-root seedlings) were estimated from 39 experiment sites covering five prefectures and five species and compared between stock types. The result of parameter estimation using hierarchal Bayesian models revealed that the median survival ratio of containerized seedlings across all species was 0.96, which was not different from that of bare-root seedlings (0.97). The estimated height and diameter growth rates were also similar between stock types. The sturdiness quotient (SQ, the ratio of height and diameter) was higher in containerized seedlings than in bare-root seedlings of all species immediately after outplanting. However, the difference in SQ between stock types diminished 1 year after outplanting. These results suggest that containerized tree seedlings generally show performances equivalent to those of bare-root seedlings after outplanting. Therefore, other properties of containerized seedlings, such as ease of cultivation and low-labor planting present more attractive advantages than those of good performance after outplanting.

The purpose of this study is to clarify the bottleneck elemental works in planting using containerized seedlings. For this purpose, the total number of 16 people planted containerized seedlings using 4 implements (hoe, dibble, spade, and planting tube), and we analyzed working efficiency and elemental works with the 4 implements. The results showed that the highest working efficiency is the hoe. The working efficiency of pitting with a dibble or spade or planting tube is lower that those of pitting with a hoe. The working efficiency of planting with planting tube is lower than that of planting with hoe. The work time to tread down around a seedling and the work time to move to the next planting ground is not affected by the difference in the planting implements. We show that the efficiency improvement of the pitting and planting is necessary for the high efficiency of the planting work using planting implements besides the hoe.

We investigated and compared the survival ratio and initial growth rate during two years after planting between the containerized and bare-root seedlings of Cryptomeria japonica in Shinanomachi, northern Nagano Prefecture, located in the cool and dry inland region in Japan. The survival ratio of the containerized seedlings was similar to that of bare-root seedlings. The first-year height growth rate was less than one cm per year for both seedling types, suggesting that the strong water stress was caused by planting shock. The second-year height and diameter growth demonstrated recovery, but containerized seedlings showed less than bare-root seedlings. We also found that the second-year growth was negatively affected by competition with weeds, suggesting that the small first-year height growth in this study site might be a serious disadvantage for healthy seedling growth and cost savings on weeding.

Consistent operation in both clearcutting and reforestation is being researched for cost reduction by using logging machines in reforestation. In this study, we researched clearcutting and reforestation productivity and cost with the vehicle logging system in three areas that included five gentle slope forest stands in Nagano Prefecture. As the results revealed labor productivity of 14.8−24.0 m³/man-day in clearcutting operations, we expect productivity of about 20 m³/man-day with similar systems. In our site preparations, the grapple loader showed higher productivity than human power, and use of the loader reduced cost 25 to 75% as compared to human power. The forwarding operation of carrying seedlings was reduced to 73% of the usual cost. The planting productivity of the containerized trees was significantly higher than that of bare-root trees, but also higher in cost. To balance cost cutting with efficiency, we expect a lower price for containerized trees.

To clarify the effects of initial height and surrounding weed trees on the height growth of 107 planted sugi (Cryptomeria japonica) trees, we investigated competition between weed trees and the sugi trees in a four-year-old plantation. In this plantation, weeding was conducted when trees were one and two years old, but was not conducted when they were three years old. The height growth of sugi was more strongly influenced by vertical suppression than lateral suppression of the crown. Height growth decreased when the top of the crown was covered by surrounding weed trees. Additionally, we found a significant positive correlation between initial size and height growth for the sugi trees whose top of crown was covered by weed trees. On the other hand, height growth of the taller sugi trees did not change regardless of the cover by weed trees, and variation in their height growth was relatively low. These results indicate that it is better to conduct weeding at the initial stage after planting to favor growth of planted sugi. Our study showed that the height of sugi and vertical competition between sugi and weed trees are useful indices to effective decision making in weeding management.

We evaluated the effects of pre-sowing treatments such as near-infrared (NIR) light sorting (for filled seeds) and fungicide cleansing on the germination rate of Cryptomeria japonica and Chamaecyparis obtusa seeds, which were stored dry for 18 months below freezing. After NIR light sorting, seed germination rates of both species were greatly increased; as for C. japonica, more than 90% of all collected seeds successfully germinated, the rate considered as the minimum requirements for containerized seedling production via single-seed sowing procedures. On the other hand, seeds of both species soaked in fungicide solution or water before sowing exhibited a tendency to germinate earlier than unsoaked controls. However, these cleansing treatments did not perfectly prevent seed deterioration due to mold breeding or putrefaction, and hence the effect was not significant at later than two weeks after sowing. It is expected that future development of methods for identifying stale seeds and/or for preventing sown seeds from deterioration will further contribute to improve production efficiency of afforestation tree seedlings.