Flora of Freshwater Wetlands in the Tsunami-Affected Zone of the Tohoku Region

Abstract

The Great East Japan Earthquake and subsequent tsunami broke open seawalls, levees, and channels on the Pacific coast of the Tohoku region, creating temporary marshes and pools at sites that had been dry before the earthquake. In ponds, paddy fields, and canals that had existed before 2011, the tsunami disturbed sediments, deposited sand, and soil and changed the growth environments of wetland plants.

After the 2011 tsunami, plant researchers and lay botanists made observations in freshwater and brackish water wetlands, where the flora recovered for the first time in decades. Many threatened, extirpated, and newly recorded species were listed by them. In this study, literature on vegetation and floristic studies of the regions of Iwate, Miyagi, and Fukushima Prefectures that were inundated by the 2011 tsunami was reviewed, focusing on studies of inland waters.

Wetland plants that appeared after the tsunami likely germinated from seed banks in the soils of the flooded areas, rather than from seeds transported from surrounding regions by dispersal vectors. They were previously common weeds in the floodplain, especially in agricultural environments.

The reported appearance frequencies for rare species are considerably higher than those for common species because the aim of most taxonomic publications is to report first findings or rare species. Herbarium specimens and literature records focus disproportionately on rare species.

These wetlands are vanishing rapidly as restoration of housing and agriculture proceeds with the infilling of wetlands. Therefore, on-site conservation of threatened aquatic and wetland species is extremely difficult.

The original version of this chapter was revised. An erratum to this chapter can be found at DOI 10.1007/978-4-431-56448-5_24

An erratum to this chapter can be found at http://dx.doi.org/10.1007/978-4-431-56448-5_24