Late Quaternary climates and river channels of the Atlantic Coastal Plain, Southeastern USA

Leigh, David S.

doi:10.1016/j.geomorph.2008.05.024

Cited by 98 publications

(55 citation statements)

References 76 publications

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“…During glacial maxima, diverse ecosystems, ranging from tundra and taiga of northern Canada to subtropical swamps and forests of the Gulf Coast, were massively compressed into an area extending just south of the North American Great Lakes region (the southern limit of most glaciation events) to somewhere south of the current northern shoreline of the Gulf of Mexico (Deevey 1949). Long-term pollen records from soil and lakebed cores in Central Florida, the Florida panhandle, and the Coastal Plain of Georgia and the Carolinas indicate that grasses and other C4 species were most frequent in the southeastern landscape during the previous glacial maximum, ranging from 60,000 to 30,000 ybp (Grimm et al 1993;Huang et al 2006;LaMoreaux et al 2009;Leigh 2008;Watts 1971;Watts et al 1992). This was the tallgrass prairie and savanna of the last glacial maximum, likely extending west along the Gulf Coast into western Texas, New Mexico, and northern Mexico.…”

Section: Geographic Distribution Of Ecotypes and Lineagesmentioning

confidence: 99%

Post-glacial evolution of Panicum virgatum: centers of diversity and gene pools revealed by SSR markers and cpDNA sequences

et al. 2011

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Switchgrass (Panicum virgatum), a central and Eastern USA native, is highly valued as a component in tallgrass prairie and savanna restoration and conservation projects and a potential bioenergy feedstock. The purpose of this study was to identify regional diversity, gene pools, and centers-of-diversity of switchgrass to gain an understanding of its post-glacial evolution and to identify both the geographic range and potential overlap between functional gene pools. We sampled a total of 384 genotypes from 49 accessions that included the three main taxonomic groups of switchgrass (lowland 4x, upland 4x, and upland 8x) along with one accession possessing an intermediate phenotype. We identified primary centers of diversity for switchgrass in the eastern and western Gulf Coast regions. Migration, drift, and selection have led to adaptive radiation in switchgrass, creating regional gene pools within each of the main taxa. We estimate that both upland-lowland divergence and 4x-to-8x polyploidization within switchgrass began approximately 1.5-1 M ybp and that subsequent ice age cycles have resulted in gene flow between ecotype lineages and between ploidy levels. Gene flow has resulted in ''hot spots'' of genetic diversity in the southeastern USA and along the Atlantic Seaboard.

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Section: Geographic Distribution Of Ecotypes and Lineagesmentioning

confidence: 99%

Post-glacial evolution of Panicum virgatum: centers of diversity and gene pools revealed by SSR markers and cpDNA sequences

et al. 2011

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“…In either case, T1f is interpreted as clastic sedimentation that outpaced the accumulation of organic matter. Other studies in the southeastern USA also have found evidence of higher magnitude flood events, as well as increased hillslope sedimentation, during the early Holocene (Goman and Leigh 2004;Leigh and Webb 2006;Leigh 2008;Liang 2008;LaMoreaux et al 2009). Although these studies are all from somewhat larger watersheds, USGS gaging records show that large and small basins in the Blue Ridge Mountain respond in a similar fashion during flood events.…”

Section: Landscape Evolutionmentioning

confidence: 86%

Section: Landscape Evolutionmentioning

confidence: 99%

“…However, Leigh (2006Leigh ( , 2008 found that bankfull floods on rivers of the Coastal Plain were much larger during the terminal Pleistocene to middle Holocene than during the late Holocene. Leigh (2008) also found that effective precipitation (runoff) was maximized during the terminal Pleistocene and first half of the Holocene. During this time period, there is also evidence of an increase in hillslope failures in the Blue Ridge Mountains, providing an excess amount of sediment, which if connected to the fluvial system would cause stream aggradation (Shafer 1988;Eaton et al 2003;Delcourt and Delcourt 2004;Leigh and Webb 2006).…”

Section: Landscape Evolutionmentioning

confidence: 99%

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Terminal Pleistocene through Holocene Evolution of Whiteoak Bottoms, a Southern Blue Ridge Mountains Peatland

McDonald

Leigh

2011

Wetlands

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Our primary objective was to develop an understanding of the geomorphic evolution of Whiteoak Bottoms (WOB), a peatland along the Nantahala River in the Southern Blue Ridge Mountains (SBRM) of western North Carolina. Radiocarbon dates directly above basal fluvial sediments returned ages of 14,000 to 15,000 cal yr BP. These ages indicate WOB is the oldest dated peatland in the SBRM and that such wetlands have persisted throughout the Holocene. Below the relatively flat surface of the wetland, paleochannels, similar to those of the modern channel, were found; suggesting a persistence of similar channel morphology since the terminal Pleistocene. The wetland's stratigraphy reveals a consistent pattern with basal fluvial cobbles being overlain by sandy channel-fill grading up into peat. Two different distinct inorganic deposits separate the lower organic deposits from the sapric peat deposits at the surface. Interestingly, we estimate more than 56% of the organic matter preserved by the wetland accumulated during the first 6,000 years of development. Overall, WOB has accumulated approximately 424 Mg/ha of carbon during the past 15,000 years. Maintenance of this wetland initially depended on the Nantahala River; however, today it is ground water and beavers that allows for the persistence of this rare landscape.

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“…Such settings have a complex floodplain geomorphology and sedimentology, possibly influenced by ground subsidence and river avulsion processes (Stouthamer and Berendsen 2001;Aslan et al 2005;Leigh 2008). These factors influence floodplain adjustment and increase flood risk but were often inadequately considered in the design of "traditional" flood control infrastructure (e.g., NRC 1995; ASCE 2007).…”

Section: Scope and Rationalementioning

confidence: 99%

Integrated Floodplain Management, Environmental Change, and Geomorphology: Problems and Prospects

Hudson

Middelkoop

2015

Geomorphic Approaches to Integrated Floodplain Management of Lowland Fluvial Systems in North America and Europe

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Recognition of the failure of old perspectives on river management and the need to enhance environmental sustainability has stimulated a new approach to river management over the past couple of decades. The manner that river restoration and integrated management are implemented, however, requires a case study approach that takes into account the influence of historic human impacts to the system, especially engineering. The process of engineering frequently results in an embanked floodplain to reduce the impact of flooding. It is increasingly recognized that floodplain embankment, while usually effective at minimizing flood risk, results in a variety of adverse consequences to the functioning of the river and associated ecosystem health. New, geomorphic-based approaches, which take into account the different modes of adjustment under the framework of integrated management, are now largely seen as the way to move forward. Implementation of such an approach, however, requires a sophisticated understanding of the fluvial system.

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Late Quaternary climates and river channels of the Atlantic Coastal Plain, Southeastern USA

Cited by 98 publications

References 76 publications

Post-glacial evolution of Panicum virgatum: centers of diversity and gene pools revealed by SSR markers and cpDNA sequences

Post-glacial evolution of Panicum virgatum: centers of diversity and gene pools revealed by SSR markers and cpDNA sequences

Terminal Pleistocene through Holocene Evolution of Whiteoak Bottoms, a Southern Blue Ridge Mountains Peatland

Integrated Floodplain Management, Environmental Change, and Geomorphology: Problems and Prospects

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