Direct shear tests on soil specimens including roots of Festuca rubra L. and Phalaris arundinacea L. based on the soil dressing seed spraying Engineering were conducted under the methods both of unconsolidated-undrained (UU) test and of constant pressure shear. Here, we discussed the relationships between the shear characteristics of soil specimen including roots of herbaceous plants and the soil cover thickness. When the soil specimen included the roots of herbaceous plants, the cohesion, c values increased, but the angle of shear resistance ,φ values stayed. Also, the c values tended to large with the thinner soil cover. The c values of P. arundinacea were larger than F. rubra with any soil cover thickness. However, the c values of F. rubra decreased to the c_blank (1.1 kN/m²) including no roots with 1.5 cm or larger in the soil cover thickness. The root length density had a negative correlation with the soil cover thickness, had a positive correlation with the c values in both of F. rubra and P. arundinacea. Therefore, the c values were affected by growing condition of the roots in the soil specimens. F. rubra needed about 1.0 cm of the soil cover thickness to keep the strength of the c values. While P. arundinacea showed good growing condition and high c values with any soil cover thickness, and high applicability of the revegetation engineering for the slope conservation in the cold region with snowfall.

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Communities of Artemisia sacrorum Ledeb. were surveyed in the Koshin District (a high-snowfall region area outside the indigenous distribution range) and on Hokkaido Island (within the indigenous distribution range) to clarify the adaptations of this species to a snowy environment. Vegetation and growth properties were surveyed in two quadrats (2 m × 2 m) per site in 2014. At all 12 sites in the Koshin District, introduced vegetation developed on roadside cut slopes after ten years and over since road construction, in general shaded by trees. However, at all seven sites in Hokkaido, herbaceous vegetation of A. sacrorum community was found in areas without trees on steep, ocean-facing slopes, involving six sparsely-vegetated grasslands on sea cliffs and one area with introduced vegetation on a reinforced slope. The elongation of creeping stems of A. sacrorum was more marked in the Koshin District. In both regions, winter buds formed on woody stems. The simultaneous production of numerous winter buds was considered advantageous for survival in snowy areas, from the viewpoint of preventing damages caused by stem bending and animals. No significant difference was observed in the average number of seeds per 100 capitula between districts, because of the large variation among sites. Similarly, no significant correlation was observed between the number of capitula and number of seeds per inflorescence. The results suggest that, despite poor growth conditions with a small number of capitula in the Koshin District, A. sacrorum survives by setting fruit occasionally and regenerating naturally.

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Recently, the habitat of sika deer has expanded to include snowy regions, and browsing damage by these deer has been reported. To promote revegetation in these snowy regions it is necessary to prevent this damage. Use of tree shelters is one method of damage prevention. To clarify the snow-pressure resistance of tree shelters, we tracked the snow depth over 1 snow season in cedar forests located on a flat site in a snowy region, and after the snowmelt we investigated the rate of damage to the shelters. We installed 20 hexagonal-column-type tree shelters (height: 140 cm) at the site. We also followed snow depth by automatic photographs taken every hour during winter 2013-2014. The snow cover period lasted at least 106 days. The maximum snow depth during the investigation period was 110 cm. No damaged or collapsed hexagonal-column-type tree shelters were observed after the snowmelt. This suggested that hexagonal-column-type tree shelters are usable year -round if the maximum snow depth is less than the height of the tree shelter.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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To consider how best to conserve flowering species in the semi-natural grassland of a montane region, we investigated plant species and flowering at sites that underwent different forms of artificial management from 2006 to 2013 at Mt. Amari in Yamanashi Prefecture. The management included simple mowing; mowing with grass removal; and mowing, grass removal, and scratching (three-step treatment) of the topsoil. These forms of management were applied in 3-year cycles in the order listed above. In each year, study plots were subjected to each form of management. A control plot was not managed. Management commenced in October 2005. The number of flowers in the control plot was smaller than in every other management plot. The numbers of flowers in May and June were greatest with grass removal and scratching every year. However, the height of vegetation and cover rates under the scratching treatment decreased after the first year and the height of vegetation in the grass removal treatment decreased after the sixth successive year of management. The extent of flowering after July did not vary with the type of management. Therefore, we are able to suggest a form of management to conserve flowering species. Mowing with grass removal every October should be conducted along trails, which are the major sightseeing areas, to maintain flowering from May to October, with such management continuing for about 6 successive years. In addition, mowing should be conducted every 3 years across a wider area to maintain flowers after July.

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This study investigated the growth response of a specific alien species, Hydrocotyle ranunculoides L. f., to differences in water current and scraping on and below the soil surface. Furthermore, growth characteristics of creeping stem cut fragments were surveyed. Non-scraped creeping stems extended about 10 m in two months. The creeping stems were cut naturally in a flowing water-current (0.23 ± 0.01 m/s) , although the biomass was significantly greater under a stagnant water situation. Plants scraped to soil depth of 1 cm showed greater total biomass than that of plants scraped only on the soil surface. Creeping stem cut fragments having 2 nodes and 3 nodes with non-terminal buds regenerated well. Biomass of the creeping stem cut fragments of 2 nodes increased to more than 80% of that of 4-node fragments. Moreover, the total number of nodes increased almost equally to the total for a 4 node fragment. Results show that the creeping stems reproduced better in the case of scraping treatment, with cutting or damage, than in a non-scraping treatment.

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This is a comparative study of a living plant (Hedera herix L.) and similar shape imitation greens which have the adsorption amount per cm² (-μg/cm²) during extended times in the outdoor environment. In addition, we considered the plant and these materials, characteristics and advantages. It was found from the result that NO₃^- -μg/cm² were larger than SO₄^2－ -μg/cm² in all measurement terms. In a similar, Warm seasons were larger than Cool seasons, too. Furthermore, NO₃^- -μg/cm² degrees were Polyester imitation green (PL) ＞ Polyethylene imitation green (PE) ＞ Polyester -Polyvinyl chloride coating imitation green (PL-PVC) ＞ Hedera. It's as the Hedera and weather resistance enhanced products (PL-PVC) had resulted in a decreased. On the other hand, SO₄^2－ -μg/cm² were not obvious differences Warm and Cool seasons. However, it became clear that the Hedera was second largest during Cool seasons.

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