[in Japanese]

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[in Japanese]

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For restoration of destroyed natural environment along the lake side, growth characteristics and water response of common reed (Phragmites australis) strains, derived from different habitats, were determined. Three strains were planted under the upland or lowland condition in the experimental field. From the results for two years, all strains grown under upland condition showed better growth as evaluated by growth parameters such as total shoot length, the number of shoots and leaves than those under lowland condition. To determine water response, reed strains were also cultivated in the pots with dry soil or under flooded condition. Under dry condition, all plants reduced their total shoot length and the number of shoots in comparison with those under wet condition, but the growth response to water condition depended on the strains. In particular, most of plants of a strain derived from the wetland died under heavy dry condition. These results suggest that appropriate genotypes of reed adapted to suitable water condition must be used for the establishment of reed stands. However, it is necessary to cultivate under dry condition for first one or two years for stimulation of early growth.

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Since the 1980 s, the forest cover type around Kyoto City, i. e., Pinus densiflora, has largely changed in urban areas because of severe damage due to pine wilt disease. In order to clarify the recent dynamics of the damaged forests, in 2007 we resurveyed four plots that had been surveyed in 1997 and examined the changes of the stand structure in these plots during a 10-year period. The broad.leaved forest evolved from damaged P. densiflora areas in 1997, and the species diversity declined during the decade. Although many P. densiflora seedlings were found in the degraded forests for lack of tall trees, they were shorter in height and fewer in number than sub-trees. From the above findings, it can be concluded that the P. densifloraforest could not recover under natural conditions. The pine wilt disease spread to the high altitude areas, suggesting that degraded forests may extend to other areas. In order to recover P. densiflora in these degraded forests, it is necessary to exclude sub-trees when many P. densiflora seedlings are survival, and other forest operation is necessary to promote the regeneration when P. densiflora seedlings are few.

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In the research area (Torino-o No. 3 landslide slope), exotic pasture grasses (Agrostis stolonifera, Festuca sp., and Lespedeza cuneata) were seeded by helicopter, after locality-certified seedlings of native species (Alnus sieboldiana and Miscanthus condensatus) had been planted for vegetation recovery. We set four fertilized plots (approximately 200 kg/10 a of manure with fowl dropping) and three non-fertilized plots in 2004, and surveyed the vegetation in every summer, from 2004 to 2009. As a result, planted seedlings grew steadily whether fertilized or not, while a phenomenon like self-thinning was observed in A. sieboldiana and the maximum plant height was observed in M. condensatus in 2008. Exotic pasture grasses decreased gradually as a whole, but still remained around 10 % in coverage. Correlation with the total percentage of coverage in exotic pasture grasses was significant only in the annual changes in the number of trees per area in the year after fertilizing. In the fertilized plots, growth of A. sieboldiana, M. condensatus and Festuca sp. increased significantly only in the year after fertilizing. Fertilizing also influenced the life forms of invaded native species and species diversity in the her-baceous layer in an early few years, however it was not suggested that the influence delay the plant community succession on a medium to long term.

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The forest topsoil that is able to gather at land development and include seed bank abundantly has competence as revegetation material. We examined the methods of forest topsoil stockpiling as revegetation material. The methods stockpiling in the outdoors by banking were examined. In addition, the method stockpiling indoors in air drying condition and in moist condition by sealing with plastic bag were examined. The stockpiling period was set in one year. Concerning stockpiling by banking in the outdoors, the topsoil that decreased buried viable seed density mostly was stockpiled in 1.5 m depth of banking covered with tarp. However, the number of 88.2% of buried viable seeds remained in this topsoil compared with the no stockpiled topsoil. The number was higher than ones of the existing result of artificial slope revegetation examination using forest topsoil. Therefore, it was concluded that the stockpiling topsoil was able to use for revegetation sufficiently. It was suggested that the topsoil stockpiling for one year by banking was able to use for revegetation, if the topsoil was included the enough amount of buried viable seeds before stockpiling. Moreover, it was concluded that the topsoil stockpiled indoors in air drying condition and in sealing moist condition was able to be used for revegetation. These results are available in revegetation using topsoil that is able to be obtained in development of forest area.

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[in Japanese]

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