The growth of seedlings of Japanese black pine (Pinus thunbergii Parl.) was promoted when the seedlings were cultivated in the presence of material of vesicular-arbuscular (VAM) fungi. The weight of the ground part, and the length and weight of the underground part increased from 1.3 to 1.7 times of that of the seedlings in the control. The elongation of the main root of seedlings where wood vinegar was applied became about the double of that of the control. The seedlings where VAM and wood vinegar were applied raised the density of the rootlet and improved in respect of the elongation of the main root. As for the seedlings that were cultivated in the presence of an organic fertilizer, the weight of the ground part and the underground part has increased by 70 percent from 30 percent. On the other hand, the length of the underground part of the seedlings has decreased oppositely by about 20 percent from 30 percent. The seedlings which was cultivated by the addition of the VAM material strengthened the drying resistance, but the resistance for the drying was reversely lowered by the use of organic fertilizer.

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A field survey was conducted on the water solubility ion in the soil at the Shonan beach, Kanagawa prefecture. As a result, it was considered that ion composition in the soil of beach was greatly affected by salt water, because main constituent in the salt water was high. It was also supposed that Na⁺ ion was main constituent of the water solubility ion and greatly affected chemical condition in the soil. Furthermore the water solubility ion such as Na⁺ and Cl^- was related to the development of coastal vegetation. Further study would be necessary to make clear the relationship between Na⁺ ion and coastal vegetation.

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The height diameter ratio of coastal black pine (Pinus thunbergii) is an important factor for forest thinning plan for over-stocked, stand. In this article, relation between the number of stands, the height diameter ratio, the area of crown projection and the volume of black pine in the Shonai Sand dune were examined. These results contribute to the disaster prevention forest in the coast or the Sea of Japan, the Tohoku district.

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