There are references in the literature that have identified the extent of the area protected from wind by artificial sand dunes. However, most these studies examined cases in which the wind flow direction was only perpendicular to the ridgelines of dunes. Given this background, a wind tunnel experiment was conducted in order to determine the area protected from the wind by an artificial sand dune when wind directions were diagonal to the ridgeline. The size of the area protected from the wind on the leeward side of the dune was smaller as diagonally as to the ridgeline of the dune. When the wind direction was perpendicular to the ridgeline of the dune, the slope of the surface measured along the wind direction was at a maximum. Two dimensional analysis of the wind direction components on the dune (profile view) revealed that the wind which flowed upward along the windward slope of the dune surface separated off at the ridge, resulting in a low wind speed area leeward of the dune. In contrast, when the wind direction was diagonal to the ridgeline of the dune, the slope of the surface measured along the wind direction was smaller than that in the perpendicular case. As a result, the wind was less likely to separate off at the ridge of the dune than it was in the perpendicular case, but flowed downward along the leeside slope of the dune with no reduction in wind speed, which weakened the formation of area low wind speed area on the leeside of the dune.

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We examined the temporal changes in vegetation and soil environment caused by volcanic activity of Mount Sakurajima via field investigations and interpreting aerial photographs taken in 1966, 1974, 1984, 1996 and 2006. The proportions of conifer and broadleaf tree areas and the timberline altitude in the study area decreased from 1966 to 1996, subsequent to volcanic activity commencing in 1972. The timberline altitude rose slowly from 1997 to 2006 because of vegetation recovery with the ebb of volcanic activity. The proportions of conifer and broadleaf tree areas decreased little after 1997. The thickness of tephra deposited since 1972, and the dry density and pH of the tephra surface layer, decreased with increasing distance from Minamidake crater.

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We investigated grain size characteristics of blown sand following severe damage to Japanese black pines in the Fukiage sand dunes. The dominant constituent coastal vegetation species from the top of the fore-dune to 50 m along the four survey lines was similar. The dominant species from 50 m to 300 m in Transects 1 and 2 (survey lines that had severely damaged Japanese black pine forest) were the same as those from 50 m to 200 m in Transects 3 and 4 (survey lines that had almost no damage). Dry bulk densities along the four transects decreased with increasing distance from the top of the fore-dune. At the same distances along transects from the top of the fore-dune, the dry bulk densities in Transects 1 and 2 were greater than those in Transects 3 and 4. D₁₀ of blown sand along the four transects decreased with increasing distance from the top of the fore-dune. D₁₀, D₅₀ and D₉₀ of the blown sand in Transects 1 and 2 were greater than those in Transects 3 and 4.

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Recently, coastal forests have received much attention for their concurrent benefits for environment and tsunami disaster protection. This study has surveyed coastal forests in Japan from viewpoints of tsunami barrier functions. Using detailed land maps and satellite images, their topographic properties, such as altitude, distance from the shoreline, growth areas, etc. are investigated. Next, for each area of the selected coastal forests, the expected tsunami run-up heights which were published by the central and local governments are surveyed. Based on both aspects of the land altitude properties and tsunami vulnerabilities, assessments on the expected tsunami reduction ability of the coastal forests have been performed.

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We clarified the difference between unthinned Pinus thunbergii coastal forest, where 10,000 trees had been planted per hectare, and similar coastal forest, where adequate thinning operations had been performed. We compared the height-dbh ratio and the clear length of the dominant trees in the overstocked, unthinned stands with those expected when the stand had been adequately thinned. Although the average height-dbh ratios of the unthinned stands were high, those of the dominant trees were low because dominance occurs among planted trees. In some cases, enough or almost enough dominant trees with height-dbh ratios of less than 70 remained. On the other hand, some unthinned stands needed many dominant trees with low height-dbh ratios. It is unclear whether, without adequate thinning, there will be enough dominant trees. Although the clear lengths of the dominant trees in the overstocked stands were about 50% of the canopy height when the canopy heights were lower, they exceeded 60% and near 70% at some stands when the canopy heights were higher. The clear lengths of the overstocked stands were higher even in the case of the dominant trees, because the average clear lengths of the stands that were adequately thinned were estimated to be fewer than 35%.

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The purpose of this study is to investigate the psychological effects of strolling with visual scenery and landscape structures that serve as factors in the effects of a coastal forest. As a result, a decrease in the T-score (POMS) was observed when the test subjects strolled in the forest, thus confirming the effect of relaxation. In addition, it was confirmed that the relaxation effect further improved when the strolling was accompanied by pleasant visual scenery. Further, it was confirmed that one of the landscape elements that improves the effect of relaxation was “the bending trunk of the pine” in Niji-no-Matsubara. Therefore, in order to maintain the landscape in the future, it would be an effective measure to ensure that the bending trunk of the pine is visible from the stroll road, and that the road passes through and around the coastal forest.

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Basic information of coastal forests such as the forest stewardship standards is important in promoting the growth and preservation of healthy forests. The purpose of this study is to validate the height measurement method for coastal forests using aerial photos taken with a small Uninhabited Airborne Vehicle (UAV). As a result, the proposed method provides good agreement with ground truth data. Consequently, our results indicate that aerial photos derived from the UAV are available for investigating tree height of coastal forests.

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We observed the acceleration of stem motion under windy conditions in a Pinus thiunbergii coastal forest in Ibaraki, Japan. We aimed to understand the sway characteristics of the trees and of simultaneous movement between trees. Every tree swayed with an obvious spectral peak in field measurements. The frequency of the spectral peak was the natural frequency and same as that observed in free vibration tests. Synchronization was observed between neighboring tree in a NS direction of tree sway. It was suggested that the collision and contact of leaves, branches and stems were avoided or declined by the synchronization of tree sway. The sway amplitudes for wind directions were different. The largest amplitude was observed for wind that had a primary frequency direction.

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