Michiro Fujihara

VR (head-mounted display) is a tool that allows you to experience a three-dimensional space. By using VR to evaluate green spaces, it is possible to evaluate them as if they were real spaces. In this study, we aimed to understand the spatial recognition characteristics of VR images of green spaces, and focused on the understanding of spatiality, the reproducibility of reality, and the effectiveness of the montage method. The method was to evaluate green spaces using VR, photography, and field evaluation, respectively, and compare the results. First, we compared the VR evaluation with the photography evaluation in terms of spatial understanding. As a result, we found that VR is superior to photography in expressing three-dimensionality. Also, regarding the reproducibility of the scene, we found that VR is superior in recognizing close view and middle distance view, and that there is a tendency for the difference in evaluation to be greater in sunny weather than in cloudy weather. In addition, when we showed the montaged images in VR and photos, both showed similar reactions regarding variability. Therefore, it can be said that the use of VR in the evaluation of green spaces is suitable for the evaluation of close to middle distance view and evaluation in fine weather.

In order to understand changes in the use of bamboo forests by wild boar, the count of the bamboo shoot feeding marks by wild boars, the position of culm, diameter of culm and a stand age-structure survey were conducted in Awaji Island from 2017 to 2018. Edible bamboo shoots appear on the ground in spring, but we found that wild boar has dug the soil and eaten bamboo shoots before the end of October. In November the number of eaten bamboo shoots accounted 0.1 to 0.7/100m²/day. The total number of the eaten bamboo shoots reached 10 to 15 /100m² during this month and this value was almost equal to the number of current-year culm appeared in the next spring. It is considered that wild boars severely affected to the regeneration of bamboo forest.

Myriophyllum aquaticum is an invasive alien aquatic plant and causes many problems such as water pollution, elimination of native plants, and obstructs water ways. To prevent these problems, suppression of M. aquaticum has been often implemented by local governments and/or NPOs. However M. aquaticum regenerate rapidly and suppression is not effective. In this study, to establish a method for eradicating M. aquaticum, vegetation and population surveys and test extermination were carried out in the field, and shading experiment took place in the laboratory. M. aquaticum covered the whole of the pond, but it rooted only on the shallow area near the waterside. During the laboratory shading experiment, M. aquaticum individuals survived the darkness for 158 days, but the length of M. aquaticum stems decreased through that period. It suggests that shorter fragments of M. aquaticum can die by short periods of darkness. At test extermination in the field, M. aquaticum did not regenerate after shading treatment with soil removed. Most fragments of M. aquaticum were removed with soil, and remnants of fragments were killed by the long darkness period. Exterminating M. aquaticum might be possible by using shading together with removing soil.

In order to prevent the expansion of bamboo forests, possibility of sustainable use of column for fuel and management of bamboo forests on the basis of the estimation of weight and volume of bamboo culm was investigated. The column density, raw weight, dry weight, apparent culm volume and culm volume was 10,460 ha^-1, 247.3t ha^-1, 120.5t ha^-1, 563.3 m³ ha^-1 and 234.2 m³ ha^-1, respectively. The dry weight of culm in Awaji Island was estimated to be 320,599 t. The culm volume recovered in eight years after having felled the bamboo by 50% density. The amount of culm consumption was 2.0t/year when the boiler was used twice a week. It seems that the selective cutting of intervals of 8 year seems to lead the sustainable use and management of bamboo forests.

In this research, we examined the possibility of tree vigor diagnosis by hand-held chlorophyll fluorometer (following, FluorPen) through comparison with the existing measuring method aiming at establishment of the simpler and more objective tree vigor diagnostic technique. Photinia glabra Thunb. were divided into the irrigation treatment groups and the non-irrigation treatment groups, and FluorPen, MINI-PAM, a chlorophyll meter, and visual diagnosis compared the decline degree of tree vigor by water stress. As a result, there was a significant difference by all the measuring methods in the irrigation treatment and the non-irrigation treatment after the 7th day of the experiment start. Moreover, only night measurement of FluorPen had a significant difference between the irrigation treatment and the non-irrigation treatment as of the 4th day.

To clarify the current status of irrigation pond abandonment and the problem for aquatic plant conservation, we investigated the percentage of abandoned pond in local area, the relationship between the depth of pond and aquatic and meadow plants diversity at farm village on hilly terrain in northern part of Awaji Island. The investigation was carried out by interviewing 133 pond manager and by field survey. We found half of ponds had been abandoned already, and, we verify the strong correlation between depth of pond and species richness of aquatic plants.

In this research, we surveyed the formation of wound wood at pruned points by the pruning examination of Cerasus speciosa (Koidz.) H. Ohba in a city park. As a result, the wound wood formed at 87 % of all pruning points, and we considered that the pruning management for C. speciosa is possible in city parks. Moreover, the differences of pruning time did not effect formation of the wound wood and the rate of covering. Therefore, time of after flowered is an appropriate time of pruning to achieve substantial amount of flowering. However, it was suggested that attention be necessary for the diameter of the pruning branch to increase formation of wound wood.

The effects of planting in the city on CO₂ uptake and alleviation of urban heat island phenomenon has received much attention recently. Varieties of general landscape shrubs with improved CO₂ absorbing and transpiration ability have been developed. In this study, differences of the improved varieties and the general landscape shrubs were evaluated by comparing CO₂ absorption and transpiration quantitatively. In the results, Gardenia jasminoides J. Ellis 'Wald' showed 67 % higher growth rate in dry weight, and higher photosynthetic rate than the original. On the other hand, Salvia microphylla 'Kirsch Red' showed high transpiration ability compared with the original.

近年，生物多様性の観点から，在来生物に被害を及ぼす外来生物が注視されている。中でもナルトサワギクは，兵庫県の淡路島および徳島県鳴門市を中心に分布域を拡大しており，外来生物規制法により特定外来生物に指定され，分布拡大防止・防除が図られている。セイタカアワダチソウやナルトサワギクなどのキク科の植物種は，道路のり面や路傍の空地などに侵入しやすい一方，森林内には侵入しにくい傾向にある。本報告では，土壌環境と植物の生育に着目し，ナルトサワギクに対し，改良客土(酸性・低栄養塩類型植生基材)を用いた成長抑制実験を行った結果を報告するものである。

There are a large number of examples poor of growth of trees in Kabokurinen of Yumebutai (34.33'30"N, 135.0'30"E) north AWAJI-island in Hyogo. (Original planting was in 1998) It is necessary to investigate the cause of poor growth and to relate to future management plan. Therefore, the weather stations were set to establish the environment of the planting sites. Tree growth factors (height, canopy spread and girth) and soil (moisture, temperature and electric conductivity) were measured. Soil amending work was also carried out to recover the vigor of Cornus florida, over 2 months period, photosynthetic rates were measured to assess effect of soil amending work. Results show that, a large improvement was suitable for a poor water area. The other way around a small improvement was suitable for a rich water area. It is important for management to consider these factors.