A planting test of Sasa nipponica was conducted under the various conditions to prevent the frost heave damages on the slopes along a road in a cold region by native S. nipponica. Studying the growth during 2 years after the planting through the soil property test, the meteorological observation and the growth investigation, it appeared that the growth was influenced by the kinds of soil and the low temperature during winter. Namely, it was clarified from the survival rate of S. nipponica that the frost-susceptible and fine-grained soil is more suitable for the growth of S. nipponica than the nonfrost-susceptible and sandy soil. Further, S. nipponica planted at the frost-susceptible soil site was larger in the average height than that at the non-frost: susceptible soil site. Since the height of grasses in all sites were smaller than that in the previous year, S. nipponica at the frost-susceptible soil grew superior to grasses which compete to grow with it. Therefore, the species seemed to achieve a suitable environment for the growth in a cold region through such cold weather.

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The thesis investigates visually handicapped person's sense to ten kinds of trees with different leaf and trunk texture. The sense and the image data were investigated touching leaves and trunks. Analysis was done using semantic differential method. For a tree with smooth texture, respondents felt elegant, comfortable or beautiful. On the other hand, they felt unpleasant or dirty for a tree with rough texture.

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Salix psammophila in use for revegetation of semi-arid regions in China is said to be going to fade awayalong with the invasion of other plants after it fixed the sands. In fact, in order to know how the growthof Salix psammophila was subjected to the influences under the competition with other plants, Salixpsammophila was allowed to be mingled with weeds or with cosmos which was assumed as a weed. Whenthe amount of weeds increased and the density of cosmos was elevated, the attained total lengths of shootwhich grew newly became shorter and the dry weight of surface/underground part decreased. And the casein which mortality was elevated was seen. What was characterized was that the attained dry weight ofsurface part of Salix psammophila in a 1/2, 000a Wagner pot was reduced to about 1/3 and the dry weightof underground part (root) was reduced to about 1/2 even though one cosmos was mingled with Salix psammophila compared with that of Salix psammophila without the mingling. As above, it was confirmedthat Salix psammophila is a typical pioneer plant that remarkably reduced the growth when it was mingledwith other plants. T/R ratio was also reduced as the increase of weeds and cosmos. From the abovefindings, it was considered that the competition due to the mingling occurred mainly at the undergroundpart, and that it was the manifestation of a relative increase in the amount of root.

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We conducted the seed banks survey of abandoned rice fields in Nakaikemi, Tsuruga City, Fukui Prefecture, Japan. We examined the soil samples from six study sites with different kinds of vegetationand confirmed the existence of diverse seed banks. Species composition of the seed banks was not entirelycoincident with the species composition of the current vegetation. We confirmed that most of the speciesgerminated from the soil of Phragmites australis and Zizania latifolia communities were the dominantplants at the early stage of abandoned rice field succession. Our study showed that plowing is effective forthe restoration of species-rich vegetation.

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We examined the effects of mixing white clover with Japanese lawngrass turf on the soil chemistry andvegetation regrowth after mowing from July to October, 1998, in order to discuss the extensive turfmanagement. The turfs of Japanese lawngrass with (MIX) and without (MONO) white clover at 2.5 and5.0 cm cutting heights were made. Inorganic nitrogen concentrations increased by mixing the white clover.Soil pH (H2O) s represented from 6.0 to 6.8 for all the turfs. At a cutting height of 2.5 cm, regrowth of Japanese lawngrass in MIX was less than that in MONO, while at a cutting height of 5.0 cm, the regrowthin MIX was more than that in MONO. The regrowth of white clover at a cutting height 5.0 cm remainedconstant, while that at a cutting height of 2.5 cm decreased throughout the investigation. The mass ofweeds was less than 10% of the entire regrown vegetation. The regrowth of weeds at a cutting height of5.0 cm was less than that at the cutting height of 2.5 cm. From these results, it was indicated that mixingwhite clover and cutting at about a 5.0 cm height might be effective way to fertilize the soil and inhibitweed regrowth in Japanese lawngrass turf.

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