We assessed vegetation recovery in landslide areas following the 2018 Hokkaido Eastern Iburi Earthquake. Six treatments were examined using combinations of wooden railings, local plants, mats for capturing seeds, and deer fences, in addition to a control. The analysis demonstrated that wooden railings may help capture large seeds. The use of local plants led to higher survival rates and achieved high vegetation coverage, while seed-capture mats decreased soil erosion. A significant effect of deer fences was not observed. The installation of local plants and seed-capture mats will contribute to the reforestation of collapsed slopes of moderate grade. The effect of deer fences should be surveyed over time.

In forests on man-made filled slopes between Haki IC and Asakura IC along Oita expressway in Japan, pruning to reduce tree height and thinning (hereafter, referred to as plantation management) were conducted by different methods. The purpose of this study was to obtain a reference for management plan in consideration for the natural environments of the surrounding area by investigating the vegetation 2 years after management. As results, plantation management did not affect the number of plant species, and it maintained a state similar to the forest edge type. The third layer that was pruned based on the target tree height was composed mainly of planted species in plantation management, and the predominance of invasive plant species was higher with a higher thinning rate. As the strength of pruning increased, dominant plant species that preferred the relatively bright forest floor became more in the fourth layer.

To effectively implement forest management designed to enhance the shallow landslide prevention function on forest slopes, it is important to correctly evaluate lateral root reinforcement. In this study, I estimated the lateral root reinforcement of sugi and hinoki plantations using a RBMw. Root pullout tests were conducted on lateral roots, and pullout force and displacement were measured. The results obtained were used to calculate parameters adopted for the RBMw, and root reinforcement was estimated by applying the model to the lateral root distribution data. Using this approach, estimated values of 6.0 and 6.8 kN/m² were obtained for the sugi and hinoki plantations, respectively, which were 43% and 46% of the values estimated using the conventional (Wu model) method. It is necessary to verify the results with actual measurements.

The present situation of C. × yedoensis ‘Somei-yoshino’ and C. speciosa was compared with the status of trees (flowering level, tree vitality index), individual sizes (height, DBH, crown area) and planting environments (light environment, planting distance, occupied area, soil hardness, habitat classification) planted in Tottori University, which was integrated and relocated in 1966. Taking flowering level and tree vitality index as objective function, other individual factors and environmental factors as explanatory variables, the generalized linear model was used to analyze two species. The factors that affected the flowering level in both species were similar: crown area, light environment, soil hardness, habitat classification for ‘Somei-yoshino’ and light environment, planting distance, soil hardness for C. speciosa. ‘Somei-yoshino’ was planted first and is larger in size, so different management policies will be necessary for both species.

We analyzed the occurrences and forest environment of drought damage of bare-root seedlings in Hinoki (Chamaecyparis obtusa Sieb. et Zucc.) plantation of Utsunomiya University Forest. Additionally, we evaluated drought tolerance due to the difference between seedling types. The mortality rate was 36.0 % and the number of dead trees was 1,012 trees. 2018 that the drought damage occurred was the year of unusual weather with low precipitation and high mean temperature, and the occurrence of drought damage was thought to be caused by long non-rainfall period and high temperature in July. High mortality rate was observed in the ridge top or steep slope with angle more than 30 degrees and thin A layer soil with low humus. While, the containerized seedlings of Hinoki had higher tolerance to drought conditions.

Longitudinal wood decay progress was investigated for Sugi (Cryptomeria japonica (Thunb. ex L.f.) D. Don) trees 5 years after bark-stripping by Japanese black bear (Ursus thibetanus japonicus Schlegel). Longitudinal variation of dynamic Young's modulus was unclear in all individuals. Longitudinal variation of moisture content in all bark-stripped trees showed lower value than partially bark-stripped and non-bark-stripped trees. On the other hand, longitudinal variation of basic density in bark-stripped trees showed constant lower values than those in non-bark-stripped trees. 1% NaOH extract contents of sapwood in bark-stripped trees were higher than those in non-bark-stripped trees at 0.2 m above ground. Thus, wood decay of trees 5 years after bark-stripping progressed in sapwood at 0.2 m above ground.

The purpose of this study is to analyze the actual usage of city parks under the epidemic of COVID-19 from changes in the floating population based on the location information service of mobile phones, and to clarify the factors that lead to the actual usage from the park characteristics. For 21 parks in 3 cities of Osaka, Sakai, and Nagoya, we compared February to September 2020 with the same period in 2019 and explored the relationship between changes in park users due to COVID-19 pandemic and park characteristics. As a result, the use of parks on weekdays tended to increase due to the epidemic of COVID-19. There was a negative correlation between the year-on-year rate of change in the number of park users and the population around the park.

In this study, in order to clarify the effect of rainwater infiltration on the reinforcing effect of vegetation works, specimens were prepared by sowing seeds of non-native herbaceous plants (KBG) in sandy and clay soil specimens to grow and develop root systems, after which the specimens were subjected to constant pressure direct shear tests under different flooding conditions. The saturation of the specimens was adjusted between three levels by flooding and dewatering. The maximum shear stress was found to decrease as the specimens approached the saturated state, regardless of the soil type. However, the root system in the specimen was confirmed to improve the toughness of the soil even at high saturation, and it is likely that the reinforcing effect of the root system is not lost by rainwater infiltration.

In this study, we constructed model embankment slopes simulating vegetation works and tried to clarify their rainfall infiltration characteristics. Three types of model embankment slopes were constructed: a bare slope with no slope protection, a slope with a turf cover, and a slope with a vegetation base on the surface. The model soil tank used in this study was designed to separately collect rainwater that infiltrated into the embankment slope and rainwater that flowed down the slope surface. A numbers of soil moisture sensors were also embedded in the embankment slope to understand the moisture behavior. As a result, the rainwater was confirmed to flow more on the surface of the slope simulating the vegetation works than on the bare slope, and the infiltration of rainwater into the deep part of the embankment was suppressed.

In this study, an erosion resistance test method for soil specimens in which herbaceous plants were grown was investigated to clarify the erosion control effect of vegetation work against raindrops. The test was conducted on soil specimens made of sandy soil in which seeds of non-native herbaceous plants (KBG) were sown to develop a root system. X-ray CT scanning was used to determine the extent of development of the root system in the soil and the erosion depth during the test. The results showed that the root system and stems of herbaceous plants increased the erosion resistance of the soil and significantly reduced the erosion depth. The test method discussed in this study was found to be very effective in evaluating the erosion control effect of vegetation work against raindrops.

In recent years, to facilitate communication and reduce stress in office workers, some companies have set up break rooms in their office. On the other hand, there are reports that greening of offices reduce stress in office workers and greening in the break room is considered to be effective for preventing stress. Regarding the greening of break rooms, effective verification of continuous use of these break rooms are necessary, but there are no studies on this so far. Thus, this study aims to understand the effects of resting in a break room with greening. We tried to measure the physical and phycological indicators of office workers over a long term. As a result, it was revealed that resting in greening break rooms improved negative emotions and the evaluation of work/workplace, indicating that resting in greening break rooms is useful for the office worker's phycological conditions.

Traditionally, brushwood used for making torches which play an essential role in the traditional Kurama Fire Festival has been gathered in local satoyama forests by local residents. In recent years, however, the sustainable procurement of brushwood has become an issue. To clarify the potential of the local forests to continuously procure the brushwood needed for the annual fire festival, this study identified the ecological characteristics of past brushwood harvest sites and assessed the “brushwood harvest potential” of local forests, that is, the quantity and quality of brushwood that can be expected to be obtained from the forests in a sustainable way. We conducted vegetation surveys in 13 of the sites that have been used for brushwood harvesting during the last 18 years. We assessed the brushwood harvest potential based on the occurrence of species that are suitable for brushwood in the forest floor vegetation and among growing trees. The results showed that survey sites with a high brushwood harvest potential could be classified as those with a high possibility for the growth of high-quality brushwood, those that contributed to a stable supply of the quantity of brushwood, and those that possessed both qualities. Furthermore, sites with a high brushwood harvest potential tended to have a high dominance of red pine.

In order to clarify the characteristics of typhoon effects on the trees in urban green spaces, observations were carried out in a green area after No.21 typhoon in 2018. There were 3122 trees in the area before typhoon, 145 snapping stems, 58 uprooting stems and 23 leaning stems were observed after the typhoon. Damaged ratio of root and stem of exotic woody species and cultivar was significantly higher than that of indigenous species. In the logistic regression analysis, the obtained regression equation between proportion of snapping stems and modules of rupture was statistically significant. These data suggest the possibility that MOR is the important parameter for estimating the windthrow by a typhoon.

Seeds of the genus Viburnum have morphophysiological dormancy; however, the mechanisms required to break the dormancy of each species are unknown. Here, we implemented a methodology that combines warm and cold stratification to break the dormancy and stimulate germination of Viburnum opulus L. var. sargentii and V. sieboldii seeds over the shortest period of time. Results showed that warm stratification of V. opulus var. sargentii seeds at 20 ℃ and 25/15 ℃ (12-hour intervals) for 75 days, initiated embryo growth and rooting which, when followed by a period of cold stratification at 5 ℃ for 90 days, led to successful germination. Seeds of V. sieboldii did not require warm stratification and were able to establish roots after a cold stratification period of approximately three and a half months. In addition, seeds of V. sieboldii were able to germinate while in refrigerated storage approximately 1-year after collection. We believe that by clarifying the germination characteristics of both species, we can shorten the growing period of seedlings used in planting.

We analyzed the effects of trampling on coastal plants using an insect protection fence in the Tottori Sand Dunes. In the second year of the fence's installation, we set up survey plots at 10 sites paired with the inside and outside of the fence, and surveyed the height, leaf length, and health of the coastal plant, Carex. pumila. The results showed that the grass height was lower and the leaf length was shorter outside the fence. The percentage of injured leaves was higher in outside. Vegetation cover around the fence was regulated by trampling in addition to site conditions. It is expected that the entry control by a simple rope fence while considering the site conditions, will be actively utilized as an effective tool for the coastal plants protection.

The size of forest fires is increasingly becoming bigger due to climate change. Forest structure contains a fuel ladder, which provides continuous fuels from the ground to the crown, is prone to fire. Taking such forest fire characteristics into consideration, we identified tree parameters that were significantly related to forest fires by employing a common forest survey technique called i-Tree. The field campaign was conducted at a natural forest of Oumu town in Hokkaido where a natural forest fire happened in 2019. The tree parameters related to forest fires are selected through the random forest modeling. Based on the results, we developed a model to estimate forest fire potential with only two parameters, tree height and diameter at breadth height.

Lacquer (Toxicodendron vernicifluum) is expected to be used as a tree in abandoned cultivated lands. However, seedling production is challenging due to its low germinability under natural conditions. In this study, we aimed to improve the germination of lacquer by examining the conditions for breaking dormancy and germination characteristics. The seeds received 0-60 minutes of sulfuric acid scarification and were exposed to 0-100 days of cold-moist stratification prior to being germinated at different temperature and light conditions. The germination percentage improved with acid scarification for more than 15 minutes together with cold-moist stratification for more than 30 days, achieving a maximum at 90%. Light was not required for germination. There was clear temperature dependence of germination and the germination was found to be maximum at around 21 ºC. The seedling production of lacquer is expected to improve by applying appropriate germination treatments.

The Reiwa 1 Boso Peninsula Typhoon caused many windthrows. Among them, we conducted tree census on the wind damage of the characteristic Sanbu-sugi cultivar forest and L. edulis forest. In the Sanbu-sugi cultivar forest established on the flat ground, all the stems with height / diameter ratio of 75 or more had stem breakage, and among the individuals with h/d ratio of 50 to 75, the stems with remarkable external symptoms of non-withered grooved wood decay disease increased stem breakage. The windthrow damage rate of the L. edulis forest established on land with a thick effective soil layer of 1 m or more was 66%, of which 85% was due to stem breakage. The windthrow damage rate of the L. edulis forest, which was established on a slope with a thin effective soil layer of 55 to 100 cm, was 75%, and 79% of L. edulis windthrown trees were due to uprooting.

In this study, to evaluate the tolerance of broadleaf trees in coastal forests to the coastal environment, the damage of component tree species was investigated on the Osato Matsubara coast in Tokushima Prefecture, Japan, which was immersed in seawater by a storm surge. The survey was conducted on 842 trees of nine species that were recorded from an area of 1.35 ha, and their planting locations and survival were examined. Based on the results, when comparing survival rates among tree species located at similar altitudes, the deciduous broadleaf trees Celtis sinensis and Zelkova serrata showed survival rates of more than 89%, which was significantly higher than that of Pinus thunbergii at approximately 38%. The survival rates of evergreen broadleaf trees, such as Cinnamomum camphora and Morella rubra, were approximately the same as that of P. thunbergii.

To obtain data on the unintentional transfer of alien species, we researched the distribution of potted plants (vegetable) in Fukuoka, western Japan, and then searched for other plant and animal species mingled in the potted plants (vegetable, flower, tree, etc.). We determined that most of the potted plants (vegetable) sold in Fukuoka originated from other prefectures, including Niigata, northeastern Japan. In several kinds of potted plants, such as vegetable, flower, tree, etc., other plant species (seedlings) including alien species were observed under experimental conditions. The rates were in 6.7%-56.3% of pots, with up to four species occurring in a single pot. Moreover, animal species, e.g. Armadillidiidae gen. sp. or Formicidae gen. sp., were also found. From these results, we conclude that plants and animals are likely to be transferred unintentionally during distribution of potted plants at a market.

To improve stress management of teachers by promoting school greening projects, we conducted an online questionnaire survey targeting teachers in elementary, middle, and high schools in Tokyo. The survey aims to investigate the utilization and perception of the teachers towards school greening situation in their own working place. As a result, we found that greenery has been rarely set in indoor space, where teachers spent most of their time, while the most relevant school greening to the teachers is just “seeing the plants while walking”. About 60% of the teachers expected school greening to be promoted for the purpose of reducing teachers' stress. Increasing plants in indoor spaces, solving the problems of plants maintenance, and verifying and spreading the effects of school greening on teachers' stress are future issues.

Indoor green is now being used in common spaces in offices with the expectation that it will improve intellectual productivity. However, there has not been sufficient verification of whether the installed common space incorporating biophilic design is used by the workers. Therefore, we conducted a questionnaire survey on the actual status of workers' use of office greening common spaces. Graphical modeling was then applied to the response results to extract usage factors. The results suggest that the frequency of use of green common spaces in offices is influenced by a variety of factors, such as workers' awareness of their use, working patterns, and the layout of green common spaces in buildings. We were able to identify factors that need to be taken into consideration when planning green common spaces to promote their use.