Effect of Soil Transplantation to Abandoned Paddy Field on the Conservation of Threatened Hydrophyte Species

Korehisa Kaneko,Hiroshi Jinguji

doi:10.4236/as.2020.1110056

Abstract

Threatened or near threatened hydrophytes, Ottelia alismoides, Monochoria korsakowii, Najas graminea, Najas minor and Chara braunii, appeared in an inundated paddy field after the 2011 Tohoku-oki Tsunami in Japan. Due to the reconstruction of roads and agricultural restoration efforts implemented following the disaster, the top soil of the paddy field was transplanted to another abandoned paddy field in 2014 to avoid extirpation of the aforementioned species. We then conducted vegetation surveys in July and September from 2014 to 2016. Monochoria korsakowii appeared at the transplantation site from 2014 to 2016, forming a large community in 2016. The volume of this species was significantly higher than that in July 2014 and 2015. Although Ottelia alismoides and Chara braunii appeared in 2014, they were not observed in 2015. Najas graminea and Najas minor were not observed during the vegetation survey, and Salvinia natans and Alisma plantago-aquatica newly appeared at the transplantation site. Our findings suggest that transplantation of surface soil and the seed bank therein to an abandoned paddy field is well suited for the conservation of hygrophytes such as Monochoria korsakowii, Ottelia alismoides and Chara braunii. Preventing disturbances that suppress the growth of herbaceous perennial plants is considered necessary for maintaining the habitats of threatened plant species.

Highlights

Our findings suggest that transplantation of surface soil and the seed bank therein to an abandoned paddy field is well suited for the conservation of hygrophytes such as Monochoria korsakowii, Ottelia alismoides and Chara braunii
Monochoria korsakowii, Ottelia alismoides and Chara braunii all emerged at the soil transplant site
Monochoria korsakowii and Chara braunii were observed in one of the control plots in 2014, we considered that these plants were derived from the donor soil

Summary

Introduction

Monochoria korsakowii was widely distributed in swampy paddy fields from Iwate to Miyagi prefectures after the tsunami [6] [7] [8] This increase in the distribution of these species was promoted by ground subsidence, which inundated paddy fields, and subsequent disturbance of surface soils containing buried seeds, which enhanced the germination of hygrophytes and promoted the establishment of hygrophyte communities after the tsunami. Many of these hygrophyte species are classified as near threatened or vulnerable in the Red Data Book of Plants published by the Ministry of Environment, Japan [9]. This study provides information on how threatened and near threatened species conservation can be effectively combined with using abandoned paddy fields following a natural disaster, like a tsunami

Methods

Results

Discussion

Conclusion