Trees play an important role in urban greening, but there are often problems with their growth, so it is necessary to monitor their growth status as basic information for appropriate tree management. The aim of this study was to analyze the relationship between the results of visual surveys of tree vitality, which are widely used as a method of monitoring tree growth, and vegetation indices obtained using UAV platforms, and to verify the effectiveness of these methods as a monitoring method for tree growth. The study focused on cherry trees planted in Yahagi Ryokuchi Hiradobashi Park (Toyota City, Aichi Prefecture). The relationship between NDVI calculated using UAV platforms and the evaluation rank of visual surveys of tree vitality was analyzed. It was found that NDVI could be used to evaluate tree health and leaf volume, and that a buffer of 1.5 m was the most suitable spatial unit for aggregating NDVI values. This study has clarified the effectiveness of NDVI for each category of vitality survey. In the future, by applying the methods of this study to various cases, it is thought that knowledge will accumulate and the methods will develop into more versatile methods, and it is hoped that this will contribute to the appropriate management of cherry trees.

Green building rating systems (GBRS) are becoming popular within the broad context of the building industry. The increasing number of projects received the WELL certification among GBRS incorporating planting design, aiming to enhance levels of human health and well-being, while few studies quantified the effects of the WELL certification and planting design on occupants’ valuation of projects. In this study, the results of the online choice experiment for the co-working space users (n=400) comparing the effects of the WELL certification, planting design, projects’ proof of health benefits, fee (or rent) on the choice of co-working spaces were used for conjoint analysis and latent class analysis. We found that the proof of health benefits and planting design had significant effects for increasing marginal willingness to pay than the WELL certification. Planting design was the most important factor for the choice of co-working spaces for 3 (73% of all participants) of all 4 latent classes, while projects’ proof of health benefits and planting design were positive factors for the choice of co-working spaces for all 4 latent classes. Further research should test the interaction between planting design and health benefits specifically from planting design, which could have large effects for increasing occupants’ valuation of GBRS projects.

Soil amendments using household food waste products are becoming popular approaches for enhancing urban sustainability. In Japan, the increasing number of households produces BC (bokashi compost using sealed containers for composting food waste mixed with fermentation agent) and DF (dehydrated food waste using home appliances specialized for thermal dehydration), while there are few studies testing effects of those home food-waste products as soil amendments for urban greening. In the 4-week laboratory experiment using LED lights for recreating the sunny summer temperature of Tokyo, we measured thermal and hydrologic properties of substrate samples made by adding BC vs. DF to commercial green roof substrates using organic (wood bark) vs. mineral (expanded shale) base materials respectively. We found that the addition of BC to green roof substrates using mineral base materials, and the addition of DF to green roof substrates using organic or mineral base materials increased field capacity and plant available water respectively. The 40% addition of DF to green roof substrates using organic base materials increased evaporation. The addition of DF to green roof substrates using organic or mineral base materials increased substrate temperature for the entire experimental period. Further research is needed for understanding plants’ effects on stormwater retention and cooling potential for green roof substrates mixed with household food waste products, while identifying the initial decomposition periods having high decomposition rates.

Among important strategies aiming to promote sustainable agriculture are soil amendments using biochar for enhancing legumes’ yield levels and biological nitrogen fixation (BNF) rates, while few study determined the optimum biochar application rates, which can depend on crop specific BNF strategies and nitrogen fixing bacteria. In this unirrigated unfertilized field study using pots, different biochar application rates (0, 30, 60 t/ha) were tested for each of two legume crops (hairy vetch: Vicia villosa and crimson clover: Trifolium incarnatum) having different BNF strategies and nitrogen fixing bacteria. We found the highest phosphorus uptake, potassium uptake, nitrogen accumulation, and yield levels for hairy vetch at biochar application rates of 60 t/ha, meaning that biochar application rates around 60 t/ha could maximize the yield levels and the incease of nitrogen contents (crop and soil) for hairy vetch. No measurements in this study for crimson clover were affected by biochar application. Further research is needed for determining the precise biochar application rates which can maximize yield levels and BNF rates for hairy vetch and crimson clover by using stable isotope ratio.

Shortage of soil water content is a major threat to wetland vegetation's decline. The effects of watering using irrigation tubes on plant communities were investigated in the Tajimagahara flood plain, Saitama Prefecture, where the nature-reserve population of a threatened species, Primula sieboldii E.Morren, has persisted. The watering system was established in 2022. Since then, the growth patterns of P. sieboldii and several major dominant species were compared for three years between plots with and without watering. P. sieboldii had longer leaves and higher stature in plots with than without watering, but only in 2022. Euphorbia adenochlora C.Morren et Decne. had higher cover and stature in plots with watering for three years. E. adenochlora performed better in earlier seasons in later years. These indicate that continued watering enhanced the steady growth of E. adenochlora with the year, which would, in turn, mask the better growth of P. sieboldii observed in 2022.

Pueraria lobata (Willd.) Ohwi subsp. lobata is listed as one of the top 100 invasive alien species in the world. In controlling P. lobata subsp. lobata, early detection and monitoring of invasions are the most important. UAV platforms should be useful for early detection and monitoring of P. lobata subsp. lobata invasions, but there are no cases of their application. Therefore, in this study, we aimed to evaluate the effectiveness of UAV platforms for monitoring P. lobata subsp. lobata in open spaces where P. lobata subsp. lobata invasions have been confirmed, and to obtain basic information for strategic management. The survey area was the forest of the Natural and Cultural Park (approx. 25 ha) in the Expo Commemorative Park (Suita City, Osaka Prefecture). Orthomosaic images were created using a UAV platform, and patch polygons of P. lobata subsp. lobata were created by visual interpretation. The distribution characteristics of P. lobata subsp. lobata were analyzed using Digital Canopy Height Model (DCHM) and park path data. In the Expo Commemorative Park, it was found that the patch area of P. lobata subsp. lobata increased 2.2 times from 2021 to 2024, and that the number of P. lobata subsp. lobata covering the tree canopy increased significantly. More than 83% of P. lobata subsp. lobata patches were distributed within 30 m of the park paths. It was found that P. lobata subsp. lobata was expanding to higher tree canopy heights. The UAV platform can be said to be effective for monitoring P. lobata subsp. lobata.