Holocene Vegetation and Paleoclimatic and Paleomagnetic History from Lake Johnston, Tasmania

AbstractLake Johnston cirque contains some of the best subalpine rainforest in Tasmania. Pollen from the sediments shows Lagarostrobos franklinii, which presently reaches 1040 m, may be a glacial relict. Nothofagus cunninghamii–Nothofagus gunnii subalpine rainforest developed between 9000 and 6000 14C yr B.P., with a maximum at 8700 14C yr B.P. After 6000 14C yr B.P. Nothofagus gunnii became more important, and from 3600 14C yr B.P. sclerophyll and heath components increased. Partial burning of the catchment occurred periodically. Early Holocene climate was warmer and wetter than late Holocene climate. The vegetation and climate changes are similar to those recorded from western South Island New Zealand and Chile. Radiocarbon dates give a sedimentation rate of 0.43 mm/yr. Cores are correlated by magnetic susceptibility. Magnetic ages are assigned by matching with the 14C-dated secular variation master curve for southeastern Australia. Magnetic ages are consistent with the 14C chronology when the former are adjusted by 350 years.

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Climate change and human disturbance of fynbos vegetation during the late Holocene at Princess Vlei, Western Cape, South Africa

The Holocene ◽

10.1177/0959683611400461 ◽

2011 ◽

Vol 21 (7) ◽

pp. 1137-1149 ◽

Cited By ~ 23

Author(s):

F.H. Neumann ◽

L. Scott ◽

M.K. Bamford

Keyword(s):

Anthropogenic Disturbance ◽

Late Holocene ◽

Climate Changes ◽

Western Cape ◽

Radiocarbon Dates ◽

The Core ◽

Pollen Types ◽

Hydrological System ◽

Vegetation And Climate ◽

Floating Mat

Pollen analysis of a core in Princess Vlei in the Fynbos Biome near Cape Town gives a 4150 year record of vegetation and climate changes followed by disturbance by colonial settlers since c. 300 years ago. Their impact replaced climate as a major factor in changing the vegetation. The chronology is based on eight radiocarbon dates. Pollen types such as Restionaceae, Ericaceae, and Proteaceae reflect changes in fynbos. Pollen indicators at the bottom of the core suggest drier conditions followed by an increase in Morella, Cyperaceae and Carpacoce pollen, which might indicate moist conditions c. 3400–2600 cal. yr BP. Drier conditions prevail c. 2600–1900 cal. yr BP. Apparent light disturbance after c. 2000 cal. yr BP might be attributed to Khoi herders. Deeper water and damp surroundings are indicated c. 1900–1000 cal. yr BP. The top of the core shows an increase of Poaceae while Restionaceae decrease with anthropogenic disturbance, including the introduction of neophytes such as Pinus ( c. 300 years ago) and Zea mays. Charcoal percentages point to intense fires after the arrival of the Europeans. Water between 105 and 75 cm indicates the development of a floating mat resulting from changes in the hydrological system possibly connected to disturbances by settlers.

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The development of blowouts and foredunes in the Ilha Comprida barrier (Southeastern Brazil): the influence of Late Holocene climate changes on coastal sedimentation

Quaternary Science Reviews ◽

10.1016/j.quascirev.2008.08.020 ◽

2008 ◽

Vol 27 (21-22) ◽

pp. 2076-2090 ◽

Cited By ~ 32

Author(s):

A.O. Sawakuchi ◽

R. Kalchgruber ◽

P.C.F. Giannini ◽

D.R. Nascimento ◽

C.C.F. Guedes ◽

...

Keyword(s):

Late Holocene ◽

Climate Changes ◽

Southeastern Brazil ◽

Holocene Climate ◽

Coastal Sedimentation

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Peat multi-proxy data from Männikjärve bog as indicators of late Holocene climate changes in Estonia

Boreas ◽

10.1080/03009480600923360 ◽

2007 ◽

Vol 36 (1) ◽

pp. 20-37 ◽

Cited By ~ 30

Author(s):

Ülle Sillasoo ◽

Dmitri Mauquoy ◽

Antony Blundell ◽

Dan Charman ◽

Maarten Blaauw ◽

...

Keyword(s):

Late Holocene ◽

Climate Changes ◽

Holocene Climate ◽

Proxy Data

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Mid-holocene climate change in Lake Bosumtwi, Ghana

Quaternary Research ◽

10.1016/s0033-5894(03)00065-6 ◽

2003 ◽

Vol 60 (2) ◽

pp. 133-141 ◽

Cited By ~ 57

Author(s):

James Russell ◽

Michael R. Talbot ◽

Brian J. Haskell

Keyword(s):

Late Holocene ◽

Climate Changes ◽

Abrupt Change ◽

Congo Basin ◽

Eastern Africa ◽

Tropical Atlantic ◽

Holocene Climate ◽

Feedback Mechanisms ◽

Equatorial Africa ◽

Nitrogen Isotopic Composition

AbstractLake Bosumtwi is one of the most widely studied palaeoclimate archives in West Africa. Results from numerous AMS 14C dates of samples from four piston cores from Lake Bosumtwi show that an abrupt sedimentary transition from a mid-Holocene sapropel to calcareous laminated muds occurred at about 3200 cal yr B.P. High-resolution analyses of the nitrogen isotopic composition of organic matter across this transition confirm its abrupt nature, and suggest that the change may signal a step toward increased aridity and intensified surface winds that affected western equatorial Africa from Ghana to the Congo basin. Northern and Eastern Africa experienced a similar abrupt shift toward aridity during the late Holocene, but at about 5000 cal yr B.P., a difference in timing that illustrates the regional nature of climate changes during the Holocene and the importance of feedback mechanisms in regulating Holocene climate variability. Furthermore, an abrupt change at about 3000 cal yr B.P. occurs at several sites adjacent to the tropical and subtropical Atlantic, which may hint at major changes in the surface temperatures of the tropical Atlantic and/or Pacific at this time.

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