Estimation of soil reinforcement (SR) by lateral roots in sugi and hinoki plantations after thinning using root bundle model with Weibull survival function (RBMw) necessitates determining and adding SR by roots of thinned trees to that of live trees. RBMw parameters were estimated from pullout tests on 5-year-old thinned tree roots and decay coefficients representing temporal change in SR by roots post-thinning were obtained. SR by roots, estimated by applying RBMw to the horizontal root distribution data obtained from 38-year-old sugi and 53-year-old hinoki forests 6 years post-thinning, was 10.9 and 12.5 kN/m² in thinned and unthinned sugi forests, and 5.9 and 6.0 kN/m² in thinned and unthinned hinoki forests, respectively. SR by decayed roots in thinned forests accounted for only 0.9 and 3.4% in sugi and hinoki forests, respectively.

Green wall plants have various functionality such as mitigating heat island, creating green space, and absorbing carbon in an urban area. A method to evaluate the various functionality is needed for construction field. This study focuses on the plant structure and deep learning was introduced to estimate the leaf area and counting leaves automatically. To achieve this, the panorama distant image was created from 3D data acquired by terrestrial laser to prepare for the deep learning model. The model for the presence or absence of leaves had 90% accuracy and the counting leaves had 72% accuracy and leaf area estimated through deep learning had 27% error compared to the destructively sampled data.

In this study, we conducted an erosion resistance test against soil specimens where Phalaris arundinacea L. had been grown. Our final objective was to determine the erosion control effect of vegetation works against raindrops using a local seedling. Foreign herbaceous plants of Poa pratensis L. were used as the control reference. X-ray CT scan was used to observe the development status of root systems in the soil and measure the erosion depth after the test. The results indicate that the erosion resistance of Phalaris arundinacea L. by the stems, leaves, and root system is comparable to that of Poa pratensis L. However, the erosion resistance of only the root system was found to increase or decrease depending on the thickness of the roots and the amount of root system in the soil.

In this study, we used a constant pressure direct shear test with low vertical stress simulating overburden pressure of the extremely shallow layer of a slope with plant root systems in order to identify the shear strength characteristics of soil which includes root systems of herbaceous plants. Specimens were prepared by compacting sandy soil where seeds of foreign herbaceous plants were planted. A cross section of the specimen was set to be larger than the Japanese geotechnical society standards to avoid loss of controlling vertical stress by the increase in friction drag at the shear test. The test results show that specimens having more developed root systems have larger shear resistance at large shear displacement. The extreme surface layer of a slope even with small overburden pressure exhibits a reinforcement effect by the root systems of vegetation works.

In this study, we developed a testing method using photogrammetry (SfM) to determine the erosion control effect of vegetation works against surface water along a slope. The test was conducted by two types of specimens: one with compacting cohesive soil and the other with growth of herbaceous plants. Test equipment comprises a slope stage and a water path with a tank. Water which overflows the tank flows downwards along the specimen surface. Photos were taken after the tests to create three-dimensional models using Metashape from Agisoft, and we measured the erosion volume therewith. These experiment results show that the stem and leaves, and root systems of herbaceous plants significantly delay the erosion start time. However, it was also found that once erosion began and vegetation was swept away, the erosion control effect was lost.

Direct shear tests were made on soil specimens, including ten types of herbaceous roots for vegetation work. In addition, strength parameters (cohesion c and angle of shear resistance φ) were aging evaluated. In the second year, the ⊿c (c value increases) in ten types of herbaceous roots showed larger than those in the first year. In addition, eight also increased the ⊿φ (φ value increases) compared with those in the former year. The results showed that the seed and nodal roots increased the cohesion c of the slope surface soil. Furthermore, the binding force of the surface soil due to the development of lateral roots increased the angle of shear resistance φ. Therefore, the herbaceous roots of RCG, ChF and MF, whose strength parameters (⊿c and ⊿φ) increase over time, are worthy of consideration as herbaceous plants that can be applied to vegetation work as alternatives TF, an exotic species under industrial control.

To analyze the psychological effect by green-space scenery focused on a light and dark, we use VR movies what we can watch this scenery for an impression evaluation. As a result, the evaluation was low for movies in which the lower part of the image was dark and the contrast of the brightness at the lower part of the image was weak. Furthermore, the space comfortability factor and activity factor were confirmed by factor analysis from the impression evaluation. Multiple regression analysis was performed to explore the relationship between factor scores and image features. The standard deviation of the pixel value of upper part was adopted, so it is suggested that the more sceneries what the upper part is high contrast is, the more a green-space scenery is comfortable.

An individual-level phenological evaluation method was developed for grasping changes in the state of inflorescences and leaf buds in 90 Japanese horse chestnuts trees (Aesculus turbinata). From the comparison of the three horse chestnut populations used for collecting the nuts in Ayabe City, Kyoto Prefecture, Japan, this result revealed that the beginning, peak, and late flowering periods of horse chestnut individuals and populations were identified through the evaluation of the inflorescence judged with 10 stages, and that this evaluation method may provide an effective perspective for elucidating the relationship between flowering synchronization and flowering period and their ecological processes. It is expected that the phenological information related to the conservation of the horse chestnut forest will be accumulated through multiple years of evaluation.

We investigated two chloroplast genome regions from trn L (UAA) 3' exon - trn F ( GAA ) and atp B - rbc L of Primula cuneifolia Ledeb. var. cuneifolia at Yoichidake in Hokkaido, and the morphological characteristics, such as grass height, tube length, flower diameter, leaf length, leaf width, and rosette diameter. As a result, 20 individuals were analyzed and haplotypes were determined for 11 individuals. The chloroplast genome of Yoichidake matched the main haplotype of Taisetsuzan - Hidaka mountains group identified in a previous study, indicating that it belongs to Taisetsuzan - Hidaka mountains group. Moreover, the populations were found to be consistent with the morphological characteristics of the standard Primula cuneifolia Ledeb. var. cuneifolia, the pin and thrum types of flowers indicated a similar ratio.

In abandoned secondary forests, Pleioblastus chino can grow in an unregulated manner and suppress the growth of the herbaceous layer. Two Callicarpa species, C. japonica and C. mollis are constituents of the shrub layer in secondary forests. This study was conducted to investigate the effects of cutting P. chino in every summer on the seed germination and survival rate of seedlings of each species. As a result of seed germination experiments in the laboratory and in the secondary forest, it was found that the germination rate was high under light conditions just after collection and that was improved even under dark conditions at low temperature by wet storage for 6 months. The survival rate of each species was higher in the cutting P. chino plot than in the non-cutting plot.

The object of this study is to determine the motivation of locals by questionnaires to consider the biodiversity of forests on the embankment slopes of expressways (hereafter referred to as “expressway forests”) in management planning. As results, the expressway forests were recognized by 65.5% of the locals, who had neutral or affirmative impressions. They recognized that the expressway forests improved the surroundings with natural environments and biodiversity, and required management plans to maintain such forests. The interest in expressway forests was primarily due to "green scenery" and “seasonal changes", just as other forests. However, local interest in expressway forests was lower than that for other forests. Therefore, consideration for "seasonal changes", "birds chirping", and "tree shade" could be the required conditions to make expressway forests with higher value.

This study focused on the spatial distribution of Ischaemum anthephoroides to evaluate the conservation effect of coastal plants by avoiding embankments for reconstruction of coastal forest in the sand dune ecotone of Sendai City, Miyagi Prefecture, Japan, which was affected by the Great East Japan Earthquake and Tsumani. In the survey, aerial images were taken in 2020 using a small unmanned aerial vehicle, and the position and size of each individual I. anthephoroides was measured. The number of I. anthephoroides was significantly lower in embankment area than in sandy beach and non-embankment area. The non-embankment area had fewer small individuals than the sandy beach area. Furthermore, there were many naturally regenerated black pine, in the non-embankment area; therefore, it was thought that the non-embankment area was difficult for new settlement and growth of I. anthephoroides.

Osbeckia chinensis L. (Melastomataceae), a tropical plant with its northern limit of distribution in semi-natural grasslands in Mie Prefecture, Honshu, Japan, is a threatened species. The purpose of this study was to determine seed germination traits of the O. chinensis. Germination tests based on gradually increasing and decreasing temperature method indicated that low temperatures for short periods of time induced secondary dormancy. The results of cold stratification for different periods (no treatment, 30-days, 60-days, 90-days) showed that untreated seeds had the highest germination rate, followed by the 90-days treatment. Germination of O. chinensis does not require light and alternating temperatures. It was inferred that buried seeds do not form a persistent seed bank.

The workplace stress check has revealed many workers are suffering from physical and mental stress. Therefore, to improve the health of the workers, we procured plant materials from the plants set up in the office and provided a total of four horticultural activities to the workers over a period of three months. And the effects were measured before and after program, focusing on work engagement, well-being, and social health. As a result, the work engagement significantly increased before and after the three-month horticultural activity. In addition, participants who felt that the activities had a positive impact on their work and personal interactions had a significant reduction in social isolation. The results indicate the providing of horticultural activities to employed people may contribute to improving work engagement and promoting social health.

Surface failure sliding at the boundaries of slopes and vegetation works covering the slopes or at extremely shallow layer of slopes happens frequently in cold and snowy regions, possibly thereby forming weak areas. As a basis to clarify the phenomenon, two-layered soil specimens having different soil properties and degree of compaction (D_c) were used. A constant pressure direct shear test was conducted at the boundary of the two layers as the shear position to identify the effect of root systems of herbaceous plants on the layer boundary. X-ray CT scan was conducted to check if the root system reached the lower layers of the specimens. The experimental results show that if root systems of herbaceous plants reach the soil of the lower layer, the boundary layer will be reinforced, thereby improving the tenacity.