Some Lower Mississippi Valley Flood Plain Biotic Communities: Their age and Elevation

Shelford, V. E.

doi:10.2307/1931109

Cited by 81 publications

(49 citation statements)

References 8 publications

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“…Shelford, 1954;Barnes, 1978;Menges and Waller, 1983; Hupp and Osterkamp, 1985; Lyon and Sagers, 1998). Elevation affects the frequency and duration of inundation and may influence the likelihood of bed load movement, the latter depending additionally on particle size and shape.…”

Section: Geomorphological Controls On Vegetation Compositionmentioning

confidence: 99%

Channel dynamics and geomorphic variability as controls on gravel bar vegetation; River Tummel, Scotland

Gilvear

Willby

2006

River Research & Apps

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This paper presents the results of an investigation into environmental controls on vegetation dynamics on gravel bars. Such environments are a hotspot of threatened plant biodiversity and the dynamics of their vegetation reflect a range of processes that should be indicative of the integrity of the wider floodplain ecosystem. The study was undertaken on a 2 ha mid-channel gravel bar complex that evolved over two decades, in response to several high magnitude flood events (including two with a return period in excess of 25 years), on a 'wandering' reach of the River Tummel, Scotland. Over 180 plant species, including a number of national or regional scarcities, had colonized. The fluvial chronology of the site was documented via sequential sets of aerial photography that revealed a number of discrete surfaces created by individual floods. Environmental heterogeneity, both within and between fluvial units, was investigated by field sampling of vegetation and abiotic variables at 66 locations. The fluvial surfaces were assigned to five habitat classes that ranged in age from two to approximately 20 years, from fine gravel to cobbles, and maintained an elevation range of up to 2.5 metres above low flow river levels. Multivariate analysis highlighted the relative importance of elevation, grain size, moisture content and infiltration and trapping of fines in controlling plant species composition. After standardizing sampling effort the habitat mosaic was found to support on average 1.36 times more species than an equivalent sample of any one habitat. In terms of biodiversity and river management, our results emphasize the importance of sustaining fluvial processes that preserve the habitat mosaic in order to conserve the characteristic biota of gravel bar complexes and river channel islands.

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Section: Geomorphological Controls On Vegetation Compositionmentioning

confidence: 99%

Channel dynamics and geomorphic variability as controls on gravel bar vegetation; River Tummel, Scotland

Gilvear

Willby

2006

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“…The capacity of A. maritima to thrive in severe environments would make it extremely well suited for primary forest succession (Ugolini 1968;Chapin et al 1994) but less competitive during secondary succession, when soil nutrients or soil moisture are less prohibitive of other species (Connell and Slatyer 1977). The present rarity of A. maritima might best be explained by its specialized and narrow realized niche and by the absence of opportunities to serve its role in primary forest succession within its range over the last 10,000 yr. During the late Pleistocene Epoch, successive episodes of glacial progression and recession and numerous episodes of widespread sediment deposition and subsequent erosion, especially in the Mississippi River drainage basin (Esling and Halberg 1985;Hajic 1985;Lively and Alexander 1985), would have provided extensive and continuous opportunities for colonization of A. maritima on wet, disturbed sites in full sunlight (Shelford 1954;Ugolini 1968;Bedinger 1978;Chapin et al 1994). With the retreat of the last great glacier (the Wisconsin ice sheet), the resumption of drainage of the Great Lakes via the St. Lawrence River, and the opening of the outlet channel for Glacial Lake Agassiz to the northeast about 10,000 yr ago, the Mississippi River basin and many other watersheds of central and eastern North America have experienced a long period of relative stability (Delcourt and Delcourt 1993;Saucier 1994).…”

Section: Ecologymentioning

confidence: 99%

Differences in Shade Tolerance Help Explain Varying Success of Two SympatricAlnusSpecies

Schrader¹,

Graves

Rice

et al. 2006

International Journal of Plant Sciences

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Alnus maritima and Alnus serrulata are riparian shrubs that occur in similar habitats in the southern and eastern United States.Alnus serrulata is abundant throughout this range, but A. maritima is rare, occurring only in small populations in Oklahoma and Georgia and on the Delmarva Peninsula. Alnus maritima is more resistant than A. serrulata to water and temperature stresses, but the degree to which insolation influences the restricted distribution of A. maritima is unknown. Our goals were to characterize the shade tolerance of A. maritima and A. serrulata and determine whether differences in shade tolerance could help explain the differing ecological success of the two species. Measurements in nature showed that leaves of A. serrulatahave greater concentrations of chlorophyll than do leaves of A. maritima, and a greater percentage of A. serrulata inhabit shaded sites. Two experiments evaluating the resistance of seedlings to light-deficit stress revealed that A. maritima had a greater photosynthetic capacity and grew more quickly than A. serrulata in full sunlight. In shade, survival of seedlings was lower and reductions in photosynthesis and growth were greater for A. maritima than for A. serrulata. We conclude that A. serrulata is tolerant and A. maritima is intolerant of shade. Moreover, we conclude that shade intolerance strongly restricts the potential niches of A. maritima within the region where the shade-tolerant A. serrulata is comparatively abundant. Alnus maritima and Alnus serrulata are riparian shrubs that occur in similar habitats in the southern and eastern United States. Alnus serrulata is abundant throughout this range, but A. maritima is rare, occurring only in small populations in Oklahoma and Georgia and on the Delmarva Peninsula. Alnus maritima is more resistant than A. serrulata to water and temperature stresses, but the degree to which insolation influences the restricted distribution of A. maritima is unknown. Our goals were to characterize the shade tolerance of A. maritima and A. serrulata and determine whether differences in shade tolerance could help explain the differing ecological success of the two species. Measurements in nature showed that leaves of A. serrulata have greater concentrations of chlorophyll than do leaves of A. maritima, and a greater percentage of A. serrulata inhabit shaded sites. Two experiments evaluating the resistance of seedlings to light-deficit stress revealed that A. maritima had a greater photosynthetic capacity and grew more quickly than A. serrulata in full sunlight. In shade, survival of seedlings was lower and reductions in photosynthesis and growth were greater for A. maritima than for A. serrulata. We conclude that A. serrulata is tolerant and A. maritima is intolerant of shade. Moreover, we conclude that shade intolerance strongly restricts the potential niches of A. maritima within the region where the shade-tolerant A. serrulata is comparatively abundant.

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“…Sediment deposition usually increases the terrestrialization rate not only through increasing aggradation, but also through eutrophication, as suspended sediment is usually nutrient-rich (Shelford 1954, Peck and Smart 1986, Bhowmik and Adams 1989, Sparks et al 1990). Plants do not succeed if they are unable to tolerate these submersion periods (primarily helophytes and hydrophytes with low reserves and growth rates; van der Valk and Bliss 1971, Hamel and Bhe Âreur 1982, Brock et al 1987, Sparks et al 1990, van den Brink et al 1995.…”

Section: The Erosional±depositional Environment and Equilibriummentioning

confidence: 99%

Vegetation as a Tool in the Interpretation of Fluvial Geomorphic Processes and Landforms in Humid Temperate Areas

Hupp

Bornette

2003

Tools in Fluvial Geomorphology

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Some Lower Mississippi Valley Flood Plain Biotic Communities: Their age and Elevation

Cited by 81 publications

References 8 publications

Channel dynamics and geomorphic variability as controls on gravel bar vegetation; River Tummel, Scotland

Channel dynamics and geomorphic variability as controls on gravel bar vegetation; River Tummel, Scotland

Differences in Shade Tolerance Help Explain Varying Success of Two SympatricAlnusSpecies

Vegetation as a Tool in the Interpretation of Fluvial Geomorphic Processes and Landforms in Humid Temperate Areas

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