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

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.

Review of Effective Vegetation Mapping Using the UAV (Unmanned Aerial Vehicle) Method

We tried more precise mapping of vegetation using UAV?(unmanned aerial vehicle), as a new method of creating vegetation maps, and we?objected to be clearly the efficient mapping of vegetation using the UAV method by comparing vegetation maps created by analysing aerial photographs taken by a UAV and an aircraft (manned flight). The aerial photography using UAV was conducted in the Niida River estuary (the secondary river flowing into Minamisoma City in Fukushima Prefecture, Japan). The photography period was in August 2013. We analysed the aerial photographs using ArcGis 9 (Esri Japan Corporation, Tokyo, Japan). The aerial photographs of the main plant communities (Phragmites australis,?Typha domingensis, and?Miscanthus sacchariflorus) taken by the UAV could clearly discriminate each plant community at the 1/50 scale. Moreover, it could clearly discriminate the shape of a plant at the 1/10 scale. We compared the vegetation maps by analysing the aerial photos taken by a UAV (2013 shooting) and an aircraft (2011 shooting). As a result, the vegetation map created by the UAV method could clearly discriminate community distributions. We conclude that vegetation surveys using UAV are possible and are capable of a highly precise community division in places where field reconnaissance is difficult. The UAV method is effective and will contribute to the improvement of research methods in the future;this method may reduce research costs associated with a reduction in field survey days and man-power.

Vegetation communities in estuarine tidal flats in the different river and basin environments of the four major rivers of Ise Bay (Suzuka, Tanaka, Kushida), Mie Prefecture, Japan

In this study, we compared and analysed vegetation communities in the estuarine tidal flats of the four major rivers of Ise Bay (Suzuka River, Tanaka River, Kushida River and Miya River) in Mie Prefecture, Japan. Along the Suzuka River, Eragrostis curvula of the exotic plant accounted for 60.0% or more of the entire surface area, and the plant volume was high. Along the Tanaka River, Suaeda maritima community occupied the sand-mud zone in the vicinity of the shoreline on gravel bars, while Phragmites australis community was distributed along a shallow lake upstream. In the Kushida River, a salt marsh plant community (a community type found in areas flooded at high tide) of Suaeda maritima, Phragmites australis and Artemisia fukudo was distributed on the sand-mud surface along the main river. A salt marsh plant community (a community type found in areas that do not flood at high tide) of Phacelurus latifolius accounted for least 50.0% of the entire surface area. Along the Miya River, the area covered by the annual salt marsh plant community type was larger than the area occupied by this community type along the other rivers. The flow volume of the Miya River was high in April, June and August-October of 2006, July and September of 2007 and April-June of 2008. The flow volume was especially high in July 2007, when it reached levels above 1500.0 m3/s;change in flow volume was also large. We suggest that a large-scale disturbance occurred in the estuary, resulting in the formation of a gravelly sandy surface where an annual salt marsh plant community of Suaeda maritime and Artemisia fukudo has been established and grown as the annual precipitation and catchment volume of the basin have increased.

The influence of changes in the degree and frequency of disturbance on the annual salt marsh plant (<i>Suaeda maritima, Artemisia fukudo</i>) communities in estuarine tidal flats: A case study of the Kushida River in Mie Prefecture, Japan

In this study, we examined the influence of changes in the degree and frequency of disturbance in estuarine tidal flats on the annual salt marsh plant communities (Suaeda maritima, Artemisia fukudo) in Mie Prefecture, Japan. Suaeda maritima and Artemisia fukudo communities occur in the branch river of the Kushida River. Although the areas occupied by these communities were very small in 2006, the Suaeda maritima community expanded significantly to 3609 m2 in 2008, and the Artemisia fukudo community expanded significantly to 2726 m2 in 2008 and 10,396 m2 in 2010. Before the onset of the investigation period in 2006, the overflow warning water level (3.5 m) and the flood fighting corps standby water level (3.0 m) each occurred on one day in August 2004 and October 2004, respectively;at those times, the water volume exceeded 1000 m3·s-1 and 1500 m3·s-1, respectively. We suggest that because much of the estuarine tidal flat erodes when the water volume exceeds 1000 m3·s&#451, the establishment of the Suaeda maritima and Artemisia fukudo communities is delayed until sufficient substrate is formed by the deposition of new sediment. In contrast, a water level of 2 - 3 m was observed on one day each in 2005, 2007 and 2009, with average water volumes of 488.5, 566.4 and 690.1 m3·s-1, respectively. We suggest that following the repeated disturbances caused by water levels of 1 - 3 m and flow volumes of 500 - 700 m3·s-1 over the bare ground exposed after flooding and erosion, Suaeda maritima is a pioneer species that colonizes on bare ground deposited by sediment transported from upstream and the sea during high tides, and following the same level of disturbance, Artemisia fukudo is secondary colonizer that has germinated and grown on the sediment deposited on the Suaeda maritima community.

Ecosystem services of coastal sand dunes saw from the aspect of Sake breweries in Chiba Prefecture, Japan: A comparison of coastal and inland areas

In this report, we reviewed the differences in the ecosystem services of coastal and inland areas surrounding 39 Sake breweries in Chiba Prefecture by investigating environmental variables (e.g., location, altitude, soil, and hardness of preparation water). The Sake breweries were located in three distinct environments: the coastal vicinity, the river plains region, and the plateau/ mountainous region. The hardness of the preparation water and the soil types in the coastal vicinity were compared with those of the river plains and the plateau/mountainous region. Strong hard and hard water sources were observed in 70% or more of the breweries in the coastal vicinity, and sand dune regosol, coarse particle brown lowland soil, and coarse particle grey soil were more prevalent along the coast than inland. Most of the Sake brewery wells in the coastal vicinity were approximately 5 - 10 munderground, and there were no great differences in the number of Sake breweries in each well depth class in the river plains and the plateau/mountains region. We analysed environmental factors (distance from the sea, soil type, water hardness and preparation water collection depth) using a principal component analysis. This analysis revealed the existence of three main environments: the coastal vicinity, the river plains and the plateau/mountainous region. We conclude that the decrease in altitude between the inland Sake breweries and those along the coast is accompanied by a corresponding increase in the hardness of preparation water (from soft water to strong hard or hard water) and shifts in soil composition from gley soil, grey lowland soil, brown forest soil, and andosol to sand dune regosol, coarse particle brown lowland soil, and coarse particle grey soil.

Traditional Food Culture (Local Cuisines, Japanese Sake) That Has Been Nurtured by the Rich Nature of the Prefecture, Japan

In Chiba Prefecture, Japan, during the Edo period (1603-1867), the development of waterway traffic by ships and the management of ports, highways and post towns around the ports progressed with the prosperity of the Edo (present-day Tokyo), which became heavily populated and the center of politics. We estimated that the demand of Japanese sake, which is luxury grocery item, was high. The freshwater layer that is abundant in mineral water to a depth of approximately 10 m is formed in coastal sand dunes. The fresh water layer is hard water, in which the concentrations of minerals such as calcium and magnesium are high. When the fresh water layer is used as the preparation water, the working rice malt and yeast in the sake brewing process become active. Japanese sake trends to be dry with a full-bodied taste. In addition, the main ingredients of local cuisines are fish and shellfish;many local cuisines are seasoned using soy sauce, miso and salt, and these local cuisines pair well with the type of Japanese sake described above. The local cuisines have been nurtured in harmony with the region’s rich nature and heritage. In the future, we need to conserve the rich natural environment of the tidal flat, coast, seaweed beds, and marine, which have been producing the main local cuisine in Chiba Prefecture, and the water source area (a successive environment on the plateau from the coast, which was previously called the coastal dune area) of the preparation water for making Japanese sake. We also need to proactively develop local production for local consumption activities. Thus, we hypothesize that if the Japanese food life is secured and the traditional food culture is continued, the region will become revitalized by the development of the exchanges in the region.

Vegetation Formation in Estuarine Tidal Flats: Influences of Basin Scale and River-Crossing Structures of the Eight Rivers of Ise Bay in Mie and Aichi Prefectures, Japan

In this study, we examined the influences of the differences in basin scale and river-crossing structures of 8 rivers of Ise Bay in Mie and Aichi Prefectures, Japan on the vegetation in the estuarine tidal flats of these rivers. The dominant plant communities of the estuarine tidal flats formed from rivers of large-scale river basins (exceeding 300 km2) were determined. In the Miya River, the dominant plant community was the Suaeda maritima and Artemisia fukudo community. In the Kushida River, the dominant plant community was composed of Phacelurus latifolius, Artemisia fukudo, Phragmites australis, and bamboo. In the Kumozu River, the dominant community was composed of the coastal plants Calystegia soldanella, Lathyrus japonicus, and Carex pumila and the exotic plant of Lolium multiflorum. The plant community of Suzuka River was dominated by the exotic plant of Eragrostis curvula. Among the estuarine tidal flats influenced by a small-scale river basin (50 km2 or less), the plant community of Shinbori River (Fukue tidal flat) was dominated by Suaeda maritima, and the plant communities of the Shio and Harai Rivers were dominated by Phragmites australis. The plant community of Tanaka River was dominated by Phragmites australis and coastal plants. Regarding the relationship between the vegetation and the river environment for each study site, we hypothesised that in a large basin area with few structures crossing the river, the river water catchment in the estuary after heavy rains caused large areas of disturbance and formed bare land, providing suitable habitat for an annual salt marsh plant community. In contrast, in cases with many structures crossing the river, a stable channel, an excavated riverbed and the suppression of runoff and the resulting disturbance of the estuary, flooding did not occur during high tide. Moreover, we hypothesised that in a small basin with many structures crossing the river, disturbance to the estuary was not likely, and the perennial salt marsh plant community of Phragmites australis would be widely distributed, except for a river type such as the Shinbori River, in which tide and river flow were managed by a final closure.

Effects of environmental factors on <i>Sparganium emersum</i>and <i>Sparganium erectum</i>colonization in two drainage ditches with different maintenance

In the Niheishimizu and Ooshimizu sections of the town of Misato in the Akita Prefecture, Northern Japan, there are many abundant spring water areas. Sparganium (Sparganium emersum and Sparganium erectum) species are widely distributed in the irrigation water that fed by spring water. The irrigation waters were divided the natural type ditch and the maintained ditch that connect with nearby natural ditch to promote environmentally friendly agriculture. This study was conducted in both sections to support the maintenance of the irrigation water fed by the abundant spring water. A vegetation survey was conducted in September of 2005. The survey collected data on the amount of vegetation cover and the stem lengths of the plant species found in selected locations of the study area. The water depths and the flow velocities were also measured in these locations. As for the growth situation of S. emersum and S. erectum, the submerged form of S. emersum was found in water approximately 15 cm deep with a surface flow velocity of approximately 7 cm/s. This species was characterised by a relatively fast flow and relatively shallow water. The emergent and submerged growth forms of S. emersum were found in waters having flow velocities faster than those associated with S. erectum. The emergent form of S. emersum grew in relatively deep water. S. emersum is more capable of adjusting to the conditions of stream habitats than S. erectum.

Effects of the inhibition of weed communities by winter-flooding

Winter-flooded paddy field is an agricultural method which putting a water among the winter, it is paid attention as an environmental friendly agriculture. Especially, it is said, winter-flooding is control paddy weeds and there is the farming potential that the annual rice yield is high. However, there is no detailed research about the effects of weed communities by winter-flooding, as the purpose of this study, we investigated the effects of the inhibition of weed communities (life cycle, harmful weed) by winter-flooding at a shore of Inba Lake, Chiba Prefecture, Japan, and compared them to paddy weeds in a dry paddy field. Methods examined the plant height (cm) and the cover degree class of all appearance species in each quadrant frame (1 m2). Quadrant in the two type paddies were 10 frames (D1-D10) at the control, and were 10 frames (W1-W10) at the treatment (Figure 1). In a winter-flooded paddy field, species number and plant volume of winter-annual plants decreased in the third winter after winter-flooding, In particular, the plant volume of Alopecurus aequalis, Cardamine flexuosa decreased significantly. We considered that the cause of this decrease was due to the depth of flooding (more than 10 cm). Eleocharis kuroguwai and Echinochloa oryzoides, which are perennial plants, Sagittaria trifolia, which is an annual plant, increased in a winter-flooded paddy field in the third summer after winter-flooding. We considered that these species grew thicker at places where the seeds germinated, and grew easily, because the conservation situation of the seeds fitted well under the winter-flooding conditions. They started to grow immediately after the drainage of water. The period of drainage coincided with increasing light intensity and temperature. In addition, the annual rice yield of the third year after winter-flooding was higher than that of the habitual practice rice field.