Ecosystem restoration projects became common in Japan recently as public works. In this social situation, a method for setting goal of ecosystem restoration is required. The author discussed about two different approaches to set goal of restoration. The first one is setting special or temporal reference. If reference site was available, detailed information which contribute setting model for restoration, can be provided. But in most cases, appropriate reference site is hardly available in neighborhood of given sites. Temporal reference is more difficult to get, because detailed ecological information of the past time is not recorded usually. But in case of its available, it is quite useful for setting model. After all, the role of special and/or temporal reference is indicating rough direction of restoration goal. Estimating environmental potential of ecosystem is another approach. There are four different dimensions of environmental potential, such as abiotic condition of the given site, relationship between source and sink of species, coaction of species and possibility of ecological succession. Among them, coaction of species is most difficult to estimate, but others could be estimated more or less. The role of estimating environmental potential is indicating possibility and limitation of restoration on given site. Combination of two approaches can provide rational direction and possibility for ecological restoration. This combined method for setting restoration goal could be useful in practice.
Currently, ecological restoration activities including “biotope creation/restoration projects, ”“compensatory mitigation projects” have been popular in Japan. However, success criteria on these activities were not clearly defined. Ecological restoration activities must have clear success criteria that directly relates to their goals/objectives. This paper reviewed mechanisms of Habitat Evaluation Procedures (HEP) that are very popular in the U.S. to identify possible success criteria on ecological restoration projects. The study showed there were three basic parameters such as “quality, ”“space, ”“time, ” that were used in HEP, In conclusion, such basic ideas of HEP will fit for ecological restoration projects to establish their goals/success criteria as well as to evaluate impacts on ecosystems both of development site and of compensatory mitigation site in Japan.
The restoration of the wetland ecosystems is an essential problem in the world, however, the evaluation technique for the functions of ecosystems, especially in the intertidal wetlands, has not been established still in spite of the ecosystems adjoining with the human life. The Functions of a wetland tend to roughly correspond with characteristics of both the water and sediments of the wetland. In this study, the 13 intertidal sandy and muddy flat wetlands were selected from Hokkaido to Okinawa, and the indicators for water and sediments were investigated as a first step of the functional ecosystem assessment in Japan. The classification for traditional landform subclass, i. e. fore-beach, estuary and lagoon, was unclearly changeable, and it often did not agree with the functional classification. In the intertidal sandy and muddy flat wetlands in Japan, the subclass fo HGM Approach should be set corresponding to the characteristics of influent water and sediments, and it was considered that the ecosystem evaluation should be carried out in each Hydrogeomorphic Unit classified at smaller-scale than the original HGM Approach in U.S.
In this study, we investigated the most suitable extensive cultivation management cycle for conserving floral diversity in a fallow paddy field. The following three studies were made for this purpose:(1) review of the examples of paddy restoration (2) vegetation survey of fallow paddy fields and (3) rhizome study of Phragmites australis. The paddy restoration works involve those aboveground and underground i.e. mowing and plowing. The following two types of plants were found to interfere with mowing: tall-stem plants (e.g. Phragmites australis and Miscanthus sacchariflorus) and rhizome and erect-stem plants (e.g. Isachne globosa and Leersia sayanuka). These plants increased greatly during the second year in fallow. In plowing, plants with strong and long rhizome (e.g. P. australis and M. sacchariflorus) were found to interfere. The weight of their rhizome increased greatly during the forth year in fallow. Plowing is four-times laborious compared to mowing in restoration work. Therefore it is suggested that cultivation of once every four years is effective in restoration from the labor point of view.
To propose reforestation plan by plant succession for the Second Tomei Expressway that is under construction, the changes of woody-plants on man-made slopes of three expressways being in operation now were studied. Woody plants that got into the slopes and dominated first were wind-dispersal plants. However, animal (bird)-dispersal woody plants increased after 18 to 19 years. The invasion of wind-dispersal woody plants got strong influence of surrounding land use and got highest invasion rate on the slopes adjoining natural forest. It thus appears that the existence of the forest to supply the seeds is the one of the most important factors to reforest the slopes by plant succession. There are few natural forests near the Second Tomei Expressway, so planting native trees on the slopes to supply seeds was proposed to accelerate plant succession and restore natural forest.
According to my annual survey, the number of the flowering plants of Aster kantoensis Kitamura on the Tame River floodplain declined from 45, 000 in 1991 to 175 in 2001. Experiments were made in 2001 to create habitats for A. kantoensis. After cutting down trees, mostly Robinia Pseudo-acacia L., and taking the surface sand away, five types of gravel dry river bed were prepared; Type A: no treatment, Type B: covered with one layer of large stones (D>10cm), Type C: one layer of stones of different sizes (D>7cm), Type D: fine sand deposits and Type E: three layers of large stones. The rate of emergence 8 days after the sowing was the highest in Type B (29%), followed by Types C, E, A and D in the order. As fine particle deposits under stones had higher moisture contents than uncovered deposits, the favorable emergence rates in Types B and C are attributable to the covering effects of stones.