Germination ecology of aquatic plants : Toward the regime shift to conservationary sound ecosystems

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(1) Restoration of a sustainable of endangered aquatic plant ; A model study on Nymphoides peltata in Lake Kasumigaura.Several theoretically expected issues, such as sudden extinction of small populations with low genetic diversity, limited seed production in small-sized local populations, and significantly high heterozygosity in adults that have survived environmental change, were ascertained through integrated studies on demography with discrimination of genets and genetics using highly polymorphic genetic markers. Investigation of genetic properties of the remnant soil seed bank suggested that the seed bank could potentially restore genetic diversity, although the fitness reduction of seed banks caused by inbreeding could affect the success of restoration. As a result of restoration efforts, increases in the number of local populations and genets in the Lake Kasumigaura metapopulation have led to population recovery.2) Restoration of lakeshore vegetation : Studies and practices in L … More ake KasumigauraRecovery of lost or degraded vegetation and plant diversity is an important but often difficult step in the wetland restoration processes. At Lake Kasumigaura, Japan, a project was launched in 2002 to recover lakeshore vegetation using soil seed banks as the plant material. In this project, lake sediments containing soil seed banks were spread thinly (~10 cm) on the surfaces of artificial lakeshores with microtopographic variations, which were constructed in front of the concrete levees. In total 180 species, including six endangered or vulnerable plants and twelve native submerged plants that had disappeared from the above-ground vegetation of the lake, were recorded on five restored lakeshores (totally 65,200 m2) during the first year of the restoration project. The distribution of each recolonized species suggested the importance of arrangement of ground height for restoration of species-rich lakeshore vegetation. Foreseen changes in the vegetation, such as the disappearance of disturbance-dependent species from the above ground vegetation, replacement of submerged-plant dominated vegetation by Typha-dominated plants, and the invasion of the invasive exotic, Solidago altissima, were recognized in the early stages of monitoring at the restored sites. Vegetation management including selective removal of the invasive exotics started as a collaborative activity among citizens, government and researchers. Less