This study evaluated the impact of the “void”, a non-tangible space in the forest, on the microclimate, rather than tangible objects such as trees and understory vegetation. A terrestrial laser was used to measure the forest void space in three dimensions and compact meteorological sensors were used to measure the temperature and humidity inside the forest. The relationship between the number of voxels for the tangible and non-tangible objects showed that the distribution of forest void structure was different by different height layer. The correlation analysis between the number of voxels and meteorological data showed that forest voids have a significant influence on minimum temperature. The previous study showed the presence or absence of forest canopy influences microclimate, however this study shows the relationships between forest structure and microclimate was obtained from the spatial distribution of forest void.

We investigated a method for easily estimating the amount of carbon fixation in seven species of plants that are used for green walls. Changes in plant length from the ground to the tip, leaf area, and dry weight as the plants grew were measured. For all plants, a significant positive correlation was found between the length from the ground to the tip and dry weight, and between leaf area and dry weight. The carbon concentration of all plants was approximately 400-450 g kg^-1. From these results, it was possible to estimate the approximate amount of carbon fixation based on the length of the plant.

From 2020 to 2023, we conducted a survey on the influence of cutting Pleioblastus chino on Japanese oak wilt (in regards to mortality or the effect on the living trees that had been attacked) growing on the forest floor in long-abandoned Quercus serrata and Quercus acutissima forest in the Kanto region. Japanese oak wilt caused by Platypus quercivorus spread from the forest edges in the study site during its initial stage. In particular Q. serrata with large trunk circumferences tended to be damaged initially. Two to three years after the survey started, damage to Q. serrata and Q. acutissima increased, and there was no longer a tendency for damage caused to be correlated with cutting P. chino or trunk circumference. Cutting of P. chino had no impact on Q. serrata, in the short term, but impacted the vegetation structure minimally.

This study evaluated the risk of occurrence of blown sand in coastal sand dune area and selected revegetation plants suitable for topography. Using a small unmanned aerial vehicle, we acquired orth-mosaic image and digital surface model and analyzed the relationship between vegetation and topography. The vegetation clearly changed depending on the distance from the shoreline and ground elevation. When we calculated the probability of occurrence of bare land based on the predictions of the classification tree, we found that it was high in low ground on the sea side and low in high ground on the land side. The value of the central part of the dunes was approximately 20% to 50%, and it was considered that Carex kobomugi was suitable in a flat location with a lot of sediment, and Ischaemum anthephoroides in a location with high ground and large slope.

The weaken conditions of Melastoma tetramerum and Piper postelsianum (both endemic to the Ogasawara Islands and listed as endangered species) are not clearly understood. In this study, we focused on water and light conditions and conducted experiments to understand how they decline. We conducted four experimental setting with the limitation of water and light to find that limited water and light caused restricted growth in both species. In addition, we evaluated their current habitat condition based on the data obtained by the experiments to find that the water conditions did not differ significantly, but light conditions were limited for some individual and variable among individuals in Ogasawara Islands. This study suggests that a light environment in their habitat should be improved to promote their growth of the two species.

In this study, a model embankment slope simulating vegetation work was constructed with sandy soil to clarify the runoff and infiltration characteristics of rainfall in summer and snowmelt water in spring. The soil boxes that were used had structures to collect water that infiltrated the embankment slope and water that ran off the slope separately. The soil boxes were mounted on a load cell to make it possible to measure the mass change of the entire equipment. Based on the measurement results during the summer season, it was confirmed that the slope with turf work allowed much rainfall to run off as surface water compared to the bare ground slope. Based on the measurement results during the snowmelt season, it was observed that snowmelt water could not deeply infiltrate the bare ground slope, the extreme surface layer became saturated, and the sediment flowed.

Reforestation using biological legacies has been proposed as a revegetation technique to conserve local ecosystem. It aims to restore forests by using the effect of biological legacy left behind after natural disturbances to enhance ecological resilience. In this study, reforestation using biological legacies, which was experimentally adopted for a part of the shallow landslide area caused by the Iburi East Earthquake, was evaluated from the viewpoint of restoration of ecosystem functions, by focusing on plant functional traits. The results showed that both the planting and matting treatments enhanced functional diversity. Seed weight, which affects the process of plant establishment, tended to increase by the planting and matting treatments. Changes in green leaf nitrogen concentration with treatment were not sufficient to contribute to recovery of litter decomposition rate.

This study aims to extract issues of creating biodiversity-friendly forests in urban areas by conducting vegetation and flora surveys on this area, which developed on a former factory site, and analyzing the current situation along with evaluating surrounding forests. As a result, 498 species of locally native plants were observed in the green space, or 74% of the native species ratio. And the number of species per unit area (100 m²) in the evergreen artificial forests and Quercus forests was 28.6 and 33.5. Missing species were detected in both artificial forests in comparison to the floristic composition of the surrounding area. To work towards target vegetation, introducing perennials and ferns in evergreen artificial forests and improving soil conditions for Ericaceae species in Quercus forests are needed.

In this study, specimens grown with reed canary grass (Phalaris arundinacea L.) were prepared using highly frost-susceptible sandy soil. These specimens were subjected to a freeze-thaw history, and then subjected to constant-pressure direct shear tests at low vertical stress. The test results showed that the shear resistance of the soil specimen containing the root system of reed canary grass decreased somewhat owing to the freeze-thaw history, but the soil reinforcement effect itself was not lost. In particular, the ductile behavior of the shear resistance increasing at a large shear displacement observed in previous studies was maintained after freeze-thaw history. These results indicate that reed canary grass is a very promising seed or seedling for use in vegetation work in snowy and cold regions.