A new approach to portable vibracoring underwater and on land

Lanesky, Douglas E.; Logan, Brian W.; Brown, R. G.; Hine, Albert C.

doi:10.1306/212f77f2-2b24-11d7-8648000102c1865d

Cited by 149 publications

(48 citation statements)

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“…Salt-marsh peat can provide a record of vegetation dating back several thousand years (8,12). To document saltmarsh community composition over the last several thousand years and test the hypothesis that cordgrass has migrated landward in response to recent increases in the rate of SLR, we recovered a series sediment cores (7.5 cm diameter) by using a vibracore rig (17) from across the modern cordgrass͞high marsh transition at these sites (Fig. 1).…”

mentioning

confidence: 99%

Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated sea-level rise

Donnelly

Bertness

2001

Proc. Natl. Acad. Sci. U.S.A.

312

207

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The distribution of New England salt marsh communities is intrinsically linked to the magnitude, frequency, and duration of tidal inundation. Cordgrass (Spartina alterniflora) exclusively inhabits the frequently flooded lower elevations, whereas a mosaic of marsh hay (Spartina patens), spike grass (Distichlis spicata), and black rush (Juncus gerardi) typically dominate higher elevations. Monitoring plant zonal boundaries in two New England salt marshes revealed that low-marsh cordgrass rapidly moved landward at the expense of higher-marsh species between 1995 and 1998. Plant macrofossils from sediment cores across modern plant community boundaries provided a 2,500-year record of marsh community composition and documented the migration of cordgrass into the high marsh. Isotopic dating revealed that the initiation of cordgrass migration occurred in the late 19th century and continued through the 20th century. The timing of the initiation of cordgrass migration is coincident with an acceleration in the rate of sea-level rise recorded by the New York tide gauge. These results suggest that increased flooding associated with accelerating rates of sea-level rise has stressed high-marsh communities and promoted landward migration of cordgrass. If current rates of sea-level rise continue or increase slightly over the next century, New England salt marshes will be dominated by cordgrass. If climate warming causes sea-level rise rates to increase significantly over the next century, these cordgrass-dominated marshes will likely drown, resulting in extensive losses of coastal wetlands. R ecent studies indicate that both climate warming (1, 2) and increases in the rate of sea-level rise (SLR) in New England (3) over the last 150 years are unprecedented in at least the last 1,000 years. The possibility that emission of greenhouse gases is influencing and will continue to influence global climate and potentially SLR has prompted considerable research into the possible implications for plant and animal communities (4). The distribution of salt-marsh communities is mechanistically linked to the duration of tidal inundation. As a result, coastal wetlands may be particularly sensitive to changes in sea level (5). Wetland loss has been documented in areas of the Mississippi River Delta (6) and Chesapeake Bay (7), where rates of local SLR exceed marsh accretion.In New England salt marshes, cordgrass (Spartina alterniflora) exclusively dominates daily f looded low-marsh elevations, whereas a mosaic of marsh hay (Spartina patens), spike grass (Distichlis spicata), and black rush (Juncus gerardi) dominates higher marsh elevations (8). Lower species borders are controlled by physical stress tolerance to flooding and soil anoxia, whereas upper species borders are controlled by interspecific plant competition (9, 10). Marsh hay and spike grass are excluded from the low marsh by low substrate oxygen levels. The ability of cordgrass to oxygenate substrates (11) allows this species to dominate frequently flooded lower-marsh elevations, where...

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mentioning

confidence: 99%

Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated sea-level rise

Donnelly

Bertness

2001

Proc. Natl. Acad. Sci. U.S.A.

312

207

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“…Average annual precipitation gradient and location of National Weather Service (NWS) stations used to construct historical precipitation record. (Lanesky et al, 1979). The cores were collected with an aluminum pipe lowered to the point of refusal, penetrating the pre-impoundment surface.…”

Section: Reservoir Sedimentation Ratesmentioning

confidence: 99%

Contrasting watershed-scale trends in runoff and sediment yield complicate rangeland water resources planning

Berg

Marcantonio

McAlister

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. Rangelands cover a large portion of the earth's land surface and are undergoing dramatic landscape changes. At the same time, these ecosystems face increasing expectations to meet growing water supply needs. To address major gaps in our understanding of rangeland hydrologic function, we investigated historical watershed-scale runoff and sediment yield in a dynamic landscape in central Texas, USA. We quantified the relationship between precipitation and runoff and analyzed reservoir sediment cores dated using cesium-137 and lead-210 radioisotopes. Local rainfall and streamflow showed no directional trend over a period of 85 years, resulting in a rainfall-runoff ratio that has been resilient to watershed changes. Reservoir sedimentation rates generally were higher before 1963, but have been much lower and very stable since that time. Our findings suggest that (1) rangeland water yields may be stable over long periods despite dramatic landscape changes while (2) these same landscape changes influence sediment yields that impact downstream reservoir storage. Relying on rangelands to meet water needs demands an understanding of how these dynamic landscapes function and a quantification of the physical processes at work.

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“…The sampling was done with a "vibracore" sampler (Lanesky et al 1979;Smith 1984). Texture characterization of core strata was made through Bouyoucos method (Casanova 1994), and total organic carbon determination through digestion with a sulfuric acid-potassium dichromate mixture (Anderson and Ingram 1993).…”

Section: Sampling and Pollen Analysismentioning

confidence: 99%

Contribution to Early Holocene vegetation and climate history of Eastern Orinoco Llanos, Venezuela, from a paleoecological record of a Mauritia L.f. swamp

Leal

Pérez²,

Bilbao³

2011

Acta Amaz.

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A palynological analysis of an organic paleosol found at 150-125 cm depth in a Mauritia swamp from the Eastern Orinoco Llanos is presented. The 25 cm pollen record summarizes the vegetation history during the Early Holocene, from 10,225 to 7,800 calendar yr BP. The vegetation was characterized by a Poaceae marsh, where Asteraceae, Melastomataceae, Schefflera-type and Phyllanthus were the most abundant shrubs and trees. Pollen-types richness was lower than that recorded today in similar environments, and Mauritia pollen was absent. Results suggest that climate was as humid as present during the beginning of the Holocene, with a decreasing trend in humidity from around 8,000-7,000 yr BP, in coincidence with the beginning of the "Early-Mid-Holocene Dryness" that affected deeply the Amazon Basin and neighboring areas. Dry climatic conditions could have existed in the study site until the Mid-Late Holocene when a Mauritia swamp developed, and humid conditions similar to present established. Main climate phases inferred in our study site fit well with regional trends recorded in other places located north Amazon Basin. However, conclusions are still limited by the lack of additional Quaternary records in the Orinoco Llanos area, avoiding regional correlations. KEYWORDS: Orinoco Llanos, Mauritia swamp, Early Holocene, paleoclimate, Early-Mid Holocene Dryness.Contribuição para a história da vegetação e clima durante o Holoceno Temprano do Llanos Orientais do Orinoco, Venezuela, a partir de um registro paleoecológico de um pântano Mauritia L.f. RESUMORealizou-se uma análise de pólen amostrada em paleossolos orgânicos, entre 150-125 cm de profundidade, em um pântano Mauritia os lhanos do Orinoco. O registro de pólen dessa amostra resumiu a história da vegetação durante o Holoceno Temprano, entre 10,225-7,800 cal. anos AP. A vegetação durante esse período foi caracterizada por um pântano de Poaceae, com maior abundância de arbustos e árvores de Asteraceae, Melastomataceae, tipo-Schefflera e Phyllanthus. Encontrou-se que a riqueza de tipos polínicos no Holoceno Temprano foi menor do que a riqueza atualmente encontrada em ambientes similares; o pólen de Mauritia esteve ausente de todas as amostras. Os resultados deste estudo sugerem que o clima durante o início do Holoceno foi úmido, semelhante ao clima atual. Houve também uma tendência de diminuição de umidade entre 8,000-7,000 anos AP, o que coincidiu com o início da "seca do Holoceno Temprano-Médio". Esta seca afetou profundamente a Bacia Amazônica e áreas adjacentes, persistindo no local de estudo até o Holoceno Médio-Final, período em que surgiram o pântano Mauritia e as condições climáticas atuais. Fases climáticas principais deduzidas se encaixam bem com as tendências regionais registradas em outros lugares localizados ao norte da Bacia Amazônica. No entanto, as conclusões ainda são limitadas pela falta de novos registros quaternários na área lhanos do Orinoco, evitando correlações regionais. PALAVRAS-CHAVE: lhanos do Orinoco, Mauritia pântano, Holoceno Tempra...

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A new approach to portable vibracoring underwater and on land

Cited by 149 publications

References 0 publications

Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated sea-level rise

Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated sea-level rise

Contrasting watershed-scale trends in runoff and sediment yield complicate rangeland water resources planning

Contribution to Early Holocene vegetation and climate history of Eastern Orinoco Llanos, Venezuela, from a paleoecological record of a Mauritia L.f. swamp

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