The expansion of woody shrub vegetation (Elaeagnus umbellata) along a regulated river channel

Kohri, Mari

doi:10.1007/978-4-431-76737-4_14

Cited by 4 publications

(12 citation statements)

References 15 publications

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“…Therefore, the hydrogeomorphic properties of the river and plant life‐history traits, particularly on seed dispersal appear to be important in structuring this type of community. Previous studies have shown that the establishment years for the present population of E. umbellata correspond to the occurrence of floods with a daily average discharge exceeding 1000 m 3 /sec over the period from 1 October to 31 December in every year between 1979 and 1995 in the Yoshino River (Kohri 2008).…”

Section: Introductionmentioning

confidence: 82%

“…1997). When mature trees were excavated during tree age ring analysis, there was always a big anchor stone carried by the root system of E. umbellata (Kohri 2008).…”

Section: Discussionmentioning

confidence: 99%

“…1999; Shin and Nakamura 2005). However, a fleshy‐fruited species, with its seeds mainly dispersed by vertebrates, sometimes forms a linear dominant community on the gravel bars (Kohri 2008).…”

Section: Introductionmentioning

confidence: 99%

“…These results have clarified that an increase in suitable habitat itself within the river system has increased the number of E. umbellata communities, as they tend to distribute on elevated terraces with coarse bed materials in the gravel bars in the Yoshino River (Kohri et al . 2000; Kohri 2008) and Naka River (Kohri et al . 2002).…”

Section: Introductionmentioning

confidence: 99%

“…1996) acts as a secondary seed dispersal mechanism (Kohri et al . 2000, 2002; Kohri 2008) to a wider area, and this natural disturbance appears to be effective in creating new safe sites for seed germination (e.g. Bill et al .…”

Section: Introductionmentioning

confidence: 99%

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Spatial–temporal distribution of ornithochorous seeds from an Elaeagnus umbellata community dominating a riparian habitat

Kohri

Kamada

Nakagoshi

2011

Plant Species Biology

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The dispersal efficiency and potential distribution of ornithochorous seeds of Elaeagnus umbellata in a riparian habitat were evaluated to clarify this species' establishment site in relation to the disturbance regime of the floodplain. Fruit removal by avian frugivores was monitored using fruit bags, and the spatial distribution of excreted seeds was quantified by seed traps set randomly on a gravel bar as an isolated seed source in the Yoshino River throughout an autumn fruiting season. Although more than 45% of the fruits remained on the twigs in the fruit bags, almost all fruits on the control twigs without fruit bags were exploited by the beginning of January. The fruit removal rate and seed dispersal distance were positively correlated with an increase in wintering bird species and their abundance. Intact bird-dispersed seeds of E. umbellata were trapped within a 400-m range and damaged seeds were limited to traps set within 50 m from the seed source. Frugivore behavior, such as feces excretion on rocks near water drinking sites and perching on surrounding woodland, greatly influenced the spatial and temporal dispersal pattern of the seed rain. In the present study, the avian frugivores showed upstream seed dispersal; thus, in years with stochastic autumnal floods, secondary dispersal via hydrochory downstream may be facilitated. The intensive seed dispersal in E. umbellata indicates that the present distribution of parent trees in the restricted elevation range of the gravel bars is the result of survival through disturbance, rather than seed dispersal limitation.

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Section: Introductionmentioning

confidence: 82%

“…1997). When mature trees were excavated during tree age ring analysis, there was always a big anchor stone carried by the root system of E. umbellata (Kohri 2008).…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatial–temporal distribution of ornithochorous seeds from an Elaeagnus umbellata community dominating a riparian habitat

Kohri

Kamada

Nakagoshi

2011

Plant Species Biology

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Flushing sediment from reservoirs triggers forestation in the downstream reaches

2014

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It was assumed that sediment release from a reservoir would trigger forestation and change the spatial pattern of tree recruitment in the downstream. This study tested these hypotheses by observation on a downstream sandbar of the Kurobe River. Prior to sediment release, Elaeagnus umbellata and Salix gilgiana were the most abundant tree species (33% and 64% of the total tree population) on the bar. The former colonized on elevated areas, whereas the latter mostly grew along the edges of river channels. After 2008 and 2009 sediment releases, a thick layer of fine sediment accumulated in active river channels and on low‐elevated areas of the bar. The particle size of the accumulated sediment was significantly lower (p < 0·01) and the moisture content was higher (p < 0·01) than in the underlying substrate. Total nitrogen, carbon and phosphorus concentrations of the accumulated sediment were higher than in the covered portions. After sediment release, a seedling flushing of both species occurred on the bar where 87% was composed of S. gilgiana and the remaining 13% was of E. umbellata. Although most of the S. gilgiana seedlings recruited on low‐lying areas, numerous individuals also grew on elevated margins of the channels and on areas dominated by E. umbellata. The accumulated sediment made changes in the substrate, which were favourable for the recruitment and spread of S. gilgiana. This study suggests that an alternative to sediment flushing for reservoir maintenance should be sought or the impacts on downstream environment should carefully be considered before an extensive sediment flushing operation. Copyright © 2014 John Wiley & Sons, Ltd.

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Ecological Functions of Autumn Olives for Improving Vegetation Species Diversity and Habitat Conditions Supporting Their Growth: A Study of Tedorigawa River, Japan

Taya,

Denda

2024

River Research & Apps

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Thus far, no studies have quantitatively investigated the ecological functions of wood communities for increasing vegetation species diversity and promoting supportive habitat conditions for their growth. To fill this gap, this study investigates the ecological function of the autumn olive (Elaeagnus umbellata var. umbellata) community, a typical native wood community of Japan. We selected the Tedorigawa River, a representative rapid river of Japan, as a case‐study subject and conducted field surveys to investigate the relationships between the autumn olive, black locust, and oriental wormwood‐kawarahako communities (among six total vegetation communities) and their respective species compositions. Hydraulic simulations helped investigate significant differences in the cover ratio of native species that grow in rivers and alien species and, differences in the physical and environmental characteristics among the three typical vegetation communities in the river channel (native grass community, native wood community, and alien wood community). The results showed that autumn olives support the growth of native species that prefer wet conditions and control alien species' growth. This ecological function is supported by the characteristic hierarchical structure of autumn olives, including low‐density trunks and leaves and low height, which create bright light conditions in the community. The autumn olive community was also found to obstruct flood flow, which enhances the deposition of fine sediments and nutrients. These characteristics enhance wet conditions to support the growth of native species that prefer these conditions.

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The expansion of woody shrub vegetation (Elaeagnus umbellata) along a regulated river channel

Cited by 4 publications

References 15 publications

Spatial–temporal distribution of ornithochorous seeds from an Elaeagnus umbellata community dominating a riparian habitat

Spatial–temporal distribution of ornithochorous seeds from an Elaeagnus umbellata community dominating a riparian habitat

Flushing sediment from reservoirs triggers forestation in the downstream reaches

Ecological Functions of Autumn Olives for Improving Vegetation Species Diversity and Habitat Conditions Supporting Their Growth: A Study of Tedorigawa River, Japan

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