Studies on the Ecology of the River Rheidol: II. An Ox-Bow of the Lower Rheidol

Jones, Herbert L.

doi:10.2307/2257152

Cited by 5 publications

(4 citation statements)

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“…1978) and annual scales (Macan 1977;Kunii & Maeda 1982;Wiegleb et al 1989). The role of floods in the fluctuations observed in organization of macrophytes communities was demonstrated by Butcher (1933), Jones (1956), and Wiegleb et al (1989). But Jones (1956) is the only one who has demonstrated the existence of a shifting mosaic at the seasonal scale on a braided former channel of the Rheidol River supplied by groundwater, and the scouring effect of flood on aquatic vegetation in this type of ecosystem.…”

Section: Discussionmentioning

confidence: 99%

“…The role of floods in the fluctuations observed in organization of macrophytes communities was demonstrated by Butcher (1933), Jones (1956), and Wiegleb et al (1989). But Jones (1956) is the only one who has demonstrated the existence of a shifting mosaic at the seasonal scale on a braided former channel of the Rheidol River supplied by groundwater, and the scouring effect of flood on aquatic vegetation in this type of ecosystem. However, the few studies conducted on former channels did not focus on both seasonal and interannual dynamics of the vegetation in these former channels, even though some Bravard et al 1986) have focused on the rate of the successional processes in cut-off channels: from several decades to one hundred years are needed to reach terrestrial forested stages on the braided former channels of the Rh6ne River.…”

Section: Discussionmentioning

confidence: 99%

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Succession and fluctuation in the aquatic vegetation of two former Rh�ne River channels

et al. 1994

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The vegetation dynamics in two former braided channels of the Rh6ne River was studied at two time scales in order to test the following hypothesis: fluctuations would occur within seasons (flood disturbances, hydrological fluctuations, phenology) while successions would occur between years. The vegetation was surveyed in 1983, 1988 and 1989 during summer for the interannual investigation, and in spring 1989, summer 1989, winter 1989 and spring 1990 for the seasonal investigation. Terrestrialization, which was observed within the same period in other braided former channels of that river, did not happen here despite the 1989 drought. However, a vegetation zone situated in the upstream part one channel seems to represent some successional trend, resulting in the establishment of Nasturtium officinale and the increasing abundance of Chara vulgaris. In disagreement with the tested hypothesis, only fluctuations are observed at the two temporal scales in the other vegetation zones. The amplitude of cyclic trajectories observed in the seasonal study depends of the degree of hydraulic disturbances (floods, drought) that affects each vegetation zone. The channel that is closer to the river is maintained at a steady state by the periodical inputs of kinetic energy during river overflows and fast floods; the disturbances wash away fine deposits and rejuvenate the vegetation mosaic. In the other former channel that is less disturbed by floods and is characterized by a thick layer of fine sediments, the groundwater inputs from numerous limnocrene springs carry away organic matter and slow down ecological successions. Abbreviations: C.A.: Correspondence Analysis. Species abbreviations used in figures are listed in Table 1. Nomenclature: Corillion, R. 1975. Flore et v6g6tation du massif armoricain: tome IV. Flore des Charophytes (Charac6es) du massif armoricain et des contr6es voisines d'Europe occidentale, Jouve (ed.),

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Succession and fluctuation in the aquatic vegetation of two former Rh�ne River channels

et al. 1994

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“…The patchy plant distribution results from vegetative growth from spatially separated sources, e.g. overwintering patches, seeds and attachment of drifting shoots (Jones, 1955;Haslam, 1978), although their importance is largely unknown.…”

Section: Introductionmentioning

confidence: 99%

Patch dynamics of the stream macrophyte, Callitriche cophocarpa

Sand‐Jensen

Madsen

1992

Freshwater Biology

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1. We examined changes in position and growth of Callitriche cophocarpa patches in a shallow section of a small Danish streain during the main expansion of plant cover between April and June. Mean upstream growth of patches was only 7.5% of downstream growth. The mean growth rate was 1.02cm day ~' in length and 0.55 cm day "' in width and the growth rates were not significantly dependent on patch size. For patches with an area (A) above 100 cm^ the growth rates in patch area (dA/dt) was proportional to patch circumference and thus y/Aand the relative growth rate {dA/dt A~^) was inversely proportional to y/A.The smallest patches (<100cm^), however, expanded less than expected because of their combined tendency to grow more slowly in patch length and width than larger patches. 2. The expansion of plant cover will be much more rapid in many medium-sized patches compared to few large patches of a similar combined area, because internal selfhmitation by light and space is partially relieved in smaller patches. We anticipate that recruitment and mortality of new-formed patches are critical steps preceding areal expansion. Quantification of these processes are needed fully to evaluate patch dynamics and space occupation.

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“…Plants tolerant of varying degrees of Xooding have developed physical and/or metabolic adaptations to deal with inundation and anoxia (Wharton et al 1982). Presumably, it is the degree to which individual species have adapted to anoxia-related stresses that has led to the distinct and drastic changes in vegetation composition over very short (meters) (Jones 1956, van der Valk and Bliss 1971, Bilby 1977, and in some cases, may completely remove Wne-sediment deposits that had accumulated since the last scouring event. Natural successional processes that occur in riverine ecosystems can be slowed or stopped, depending on the intensity and frequency of Xood scouring (Sparks et al 1990, Foeckler et al 1991, Mu È ller 1995.…”

Section: Plant Communities and Dynamics In Bottomlandsmentioning

confidence: 99%