Vegetation changes and topographic feature in the delta of Obitsu River in Tokyo Bay

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 many estuarine tidal flats in Ise Bay, different plant communities are present, as described in the Red Data Book of Japan [2]- [4]. The formation of vegetation in estuarine tidal flats is influenced by the ground level [5], the difference between tidal level and surface sediments [6] [7], the scale and frequency of disturbance due to differences in basin areas and annual precipitation [8] [9], and the responses of a dynamic ecosystem to repeated destruction and restoration [10]. In particular, salt marsh plant communities are exposed to the impact of sediment dynamics and the physical environment [11]- [14].…”

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

“…With respect to the growth environment of these species, Suaeda maritima disseminates its seed via the tide [15] and may form soil seed bank [16]. The Suaeda maritima community occurs at low elevations that are disturbed by flooding at high tide [3]. In addition, the Suaeda maritima community prefers the fine gravel and pebble gravel substrate that occurs below the spring high tide level [17].…”

“…We suggest that, although we found on the ground that Artemisia fukudo and Suaeda maritima were co-occured, Artemisia fukudo grows more readily than Suaeda maritima at higher elevations. Consequently, it seems likely that, following the repeated disturbances of water levels of 1 -3 m and flow volumes of 480 -700 m 3 •s −1 over the bare ground eroded by massive flooding in 2004, the Suaeda maritima community was established on the higher ground formed by the sediment transported from upstream and the sea during high tides and subsequently deposited. In addition, when this same level of disturbance occurred, Artemisia fukudo germinated and grew on the ground that was made higher by the sediment deposited on the Suaeda maritima community.…”

“…In recent years, these species have undergone declines due to coastal development, bank protection and other factors. Several environmental factors influence the habitat preferences of plants in estuarine tidal flats, including elevation and flood frequency [3], soil environment (salinity, humidity, particle size distribution, depth, oxidation-reduction potential), disturbance by floods, competition with other plants and other factors [4,5]. The composition of the salt marsh plant community is influenced by sediment dynamics and the physical environment [6,9].…”

“…We suggest that following the repeated disturbances caused by water levels of 1 -3 m and flow volumes of 500 -700 m 3 •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.…”