A 180,000-year pollen record from Owens Lake, CA: terrestrial vegetation change on orbital scales

2003 ◽  
Vol 59 (3) ◽  
pp. 430-444 ◽  
Author(s):  
Wallace B. Woolfenden
Keyword(s):  
Sierra Nevada ◽  
Vegetation Change ◽  
Vegetation History ◽  
Pollen Record ◽  
Terrestrial Vegetation ◽  
Subalpine Forests ◽  
Owens Lake ◽  
Ice Cap ◽  
Juniper Woodland ◽  
Warm Desert

AbstractPollen from the upper 90 m of core OL-92 from Owens Lake is a climatically sensitive record of vegetation change that indicates shifts in the plant associations representing warm and cold desertscrub, pinyon–juniper woodland, and pine–fir forest during the past 180,000 years. These changes are synchronized with glacial–interglacial cycles. During glacial and stadial climates, juniper woodland expanded downslope and replaced warm desert shrubs while upper montane and subalpine forests in the arid Inyo Mountains also expanded, and those in the Sierra Nevada were displaced by the ice cap and periglacial conditions. Conversely, during interglacial and interstadial climates, warm desert plants expanded their range in the lowlands, juniper and sagebrush retreated upslope, and montane and subalpine forests expanded in the Sierra Nevada. The reconstructed vegetation history demonstrates a regional climatic response, and the congruence of the pollen sequence with marine and ice cap oxygen isotope stratigraphies suggests a link between regional vegetation and global climate change at orbital scales.

Ice-Core Pollen Record of Climatic Changes in the Central Andes during the last 400 yr

2005 ◽  
Vol 64 (2) ◽  
pp. 272-278 ◽  
Author(s):  
Kam-biu Liu ◽  
Carl A. Reese ◽  
Lonnie G. Thompson
Keyword(s):  
Little Ice Age ◽  
Ice Core ◽  
Climatic Changes ◽  
Ice Age ◽  
Striking Similarity ◽  
Pollen Record ◽  
Dry Period ◽  
Proxy Records ◽  
Ice Cap ◽  
Ice Accumulation

AbstractThis paper presents a high-resolution ice-core pollen record from the Sajama Ice Cap, Bolivia, that spans the last 400 yr. The pollen record corroborates the oxygen isotopic and ice accumulation records from the Quelccaya Ice Cap and supports the scenario that the Little Ice Age (LIA) consisted of two distinct phases�"a wet period from AD 1500 to 1700, and a dry period from AD 1700 to 1880. During the dry period xerophytic shrubs expanded to replace puna grasses on the Altiplano, as suggested by a dramatic drop in the Poaceae/Asteraceae (P/A) pollen ratio. The environment around Sajama was probably similar to the desert-like shrublands of the Southern Bolivian Highlands and western Andean slopes today. The striking similarity between the Sajama and Quelccaya proxy records suggests that climatic changes during the Little Ice Age occurred synchronously across the Altiplano.

scholarly journals Grassland fire ecology has roots in the late Miocene

2018 ◽  
Vol 115 (48) ◽  
pp. 12130-12135 ◽  
Author(s):  
Allison T. Karp ◽  
Anna K. Behrensmeyer ◽  
Katherine H. Freeman
Keyword(s):  
Late Miocene ◽  
Fire Ecology ◽  
Vegetation Change ◽  
Global Climate ◽  
Indian Subcontinent ◽  
Strong Association ◽  
Feedback System ◽  
Terrestrial Vegetation ◽  
Precipitation Seasonality ◽  
Seasonal Extremes

That fire facilitated the late Miocene C4grassland expansion is widely suspected but poorly documented. Fire potentially tied global climate to this profound biosphere transition by serving as a regional-to-local driver of vegetation change. In modern environments, seasonal extremes in moisture amplify the occurrence of fire, disturbing forest ecosystems to create niche space for flammable grasses, which in turn provide fuel for frequent fires. On the Indian subcontinent, C4expansion was accompanied by increased seasonal extremes in rainfall (evidenced by δ18Ocarbonate), which set the stage for fuel accumulation and fire-linked clearance during wet-to-dry seasonal transitions. Here, we test the role of fire directly by examining the abundance and distribution patterns of fire-derived polycyclic aromatic hydrocarbons (PAHs) and terrestrial vegetation signatures inn-alkane carbon isotopes from paleosol samples of the Siwalik Group (Pakistan). Two million years before the C4grassland transition, fire-derived PAH concentrations increased as conifer vegetation declined, as indicated by a decrease in retene. This early increase in molecular fire signatures suggests a transition to more fire-prone vegetation such as a C3grassland and/or dry deciduous woodland. Between 8.0 and 6.0 million years ago, fire, precipitation seasonality, and C4-grass dominance increased simultaneously (within resolution) as marked by sharp increases in fire-derived PAHs, δ18Ocarbonate, and13C enrichment inn-alkanes diagnostic of C4grasses. The strong association of evidence for fire occurrence, vegetation change, and landscape opening indicates that a dynamic fire–grassland feedback system was both a necessary precondition and a driver for grassland ecology during the first emergence of C4grasslands.

Intimations on the Tertiary vegetation of southern Africa

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 345-354 ◽  
Author(s):  
J. A. Coetzee
Keyword(s):  
Southern Africa ◽  
Major Change ◽  
Pollen Record ◽  
Vegetation Shifts ◽  
Ice Cap ◽  
Tropical Vegetation ◽  
Cape Peninsula ◽  
Benguela Current ◽  
And Migration ◽  
The Antarctic

Fossil pollen sequences from the Cape Peninsula and the Saldanha region indicate that sub tropical vegetation and climates existed in these regions during the Miocene. The pollen record from the Cape Peninsula may point to the extinction of some taxa by the terminal Miocene/Early Pliocene with the subsequent strong development of macchia. This major change can probably be related to the maximum build-up of the Antarctic ice-cap in the latest Miocene and the accompanying profound palaeoceanographic changes such as the major cooling of the Benguela current with its effect on the aridification of the Namib desert, and the global glacio-eustatic sea level drop.Parallel palynological and lithological studies in the Saldanha region show that prominent Miocene vegetation shifts were linked to profound local changes in the palaeoenvironment associated with the northward migration of the Miocene Berg River. Such studies are of paramount importance for the possible assessment of the causes of changes in the palaeoenvironment and should first be carried out at many more sites over a wide region. It is to some extent premature to draw firm conclusions as to the origin and migration of some taxa in southern Africa. The record of very primitive angiosperms such as the ClavatipolleniteslAscarina complex and Winteraceae is of considerable phytogeographic interest.

Mesolithic to Bronze Age Vegetation Change and Human Activity in the Exe Valley, Devon, UK

2003 ◽  
Vol 69 ◽  
pp. 161-181 ◽  
Author(s):  
R.M. Fyfe ◽  
A.G. Brown ◽  
B.J. Coles
Keyword(s):  
Bronze Age ◽  
Human Activity ◽  
Vegetation Change ◽  
Vegetation History ◽  
Valley Floor ◽  
Domestic Activity ◽  
Vegetation Disturbance ◽  
Wide Range ◽  
Slope Vegetation ◽  
The Bronze Age

This paper presents the results of the first investigation of vegetation change and human activity from a river valley west of the Somerset Levels. The record is contrasted with the pollen and archaeological record from south-west uplands (Dartmoor and Exmoor) and the Somerset Levels. Vegetation change and archaeological evidence are shown to be generally consistent, with evidence from the middle valley of Mesolithic vegetation disturbance (with nearby lithics), Neolithic clearance of terraces and slopes in the lower valley and Neolithic–Bronze Age ceremonial and domestic activity, but in the upper reach the maintenance of wooded valley floor conditions probably with management until historic times. The valley floor and surrounding slope vegetation history is found to be significantly different to that of the uplands with lime and elm being significant components of the prehistoric woodland record. The data suggest that lime is restricted to terraces and lowlands below 200 m OD throughout the prehistoric period. The pollen data from the valley suggest the lowlands had a rich and mixed ecology providing a wide range of resources and that, despite less visible archaeological remains, human activity is manifest through palynological evidence from the Mesolithic to the Bronze Age. The largest expanse of valley-floor terrace, the Nether Exe Basin, which was at least partially deforested in the early Neolithic contains a rich assemblage of Neolithic–Bronze Age ceremonial, funerary and domestic archaeology associated with an early and clear palynological record of woodland clearance, arable and pastoral activity.

scholarly journals The Holocene Cedrus pollen record from Sierra Nevada (S Spain), a proxy for climate change in N Africa

2020 ◽  
Vol 242 ◽  
pp. 106468
Author(s):  
Gonzalo Jiménez-Moreno ◽  
R. Scott Anderson ◽  
María J. Ramos-Román ◽  
Jon Camuera ◽  
Jose Manuel Mesa-Fernández ◽  
...  
Keyword(s):  
Climate Change ◽  
Sierra Nevada ◽  
Pollen Record ◽  
The Holocene

scholarly journals A Holocene pollen record of savanna establishment in coastal Amapá

2008 ◽  
Vol 80 (2) ◽  
pp. 341-351 ◽  
Author(s):  
Mauro B. de Toledo ◽  
Mark B. Bush
Keyword(s):  
Vegetation Change ◽  
Human Impacts ◽  
Detrended Correspondence Analysis ◽  
Fire Frequency ◽  
Pollen Record ◽  
Human Occupation ◽  
Sample Distribution ◽  
River Flooding ◽  
History Of ◽  
Tremendous Impact

The main goal of this study was to investigate how climate and human activities may have influenced ecotonal areas of disjoint savannas within Brazilian Amazonia. The fossil pollen and charcoal records of Lake Márcio (Amapá) were used to provide a Holocene palaeoecological history of this region. Detrended correspondence analysis (DCA) was used to enhance the patterns of sample distribution along the sediment core. A marked vegetation change from closed forests with swamp elements to open flooded savanna at c. 5000 yrs BP was evident from the pollen record. Charcoal analysis revealed a pattern of increased accumulation of particles coincident with the establishment of savannas, suggesting higher fire frequency and human impacts near the lake. A 550-year sedimentary hiatus suggests that the lake depended heavily on floodwaters from the Amazon River, and that it became suddenly isolated from it. When sedimentation restarted in the lake, the environment had changed. A combination of factors, such as reduced river flooding, palaeofires and human occupation may have had a tremendous impact on the environment. As there are no other major changes in vegetation, after 4700 yrs BP, it is plausible to assume that the modern mosaic vegetation formed at that time.

A 23,000-yr Pollen Record from Lake Euramoo, Wet Tropics of NE Queensland, Australia

2005 ◽  
Vol 64 (3) ◽  
pp. 343-356 ◽  
Author(s):  
Simon G. Haberle
Keyword(s):  
New Record ◽  
Vegetation Change ◽  
Fire History ◽  
World Heritage ◽  
Pollen Record ◽  
Orbital Forcing ◽  
Wet Tropics ◽  
The Relationship ◽  
Warm Temperate ◽  
Significant Factors

AbstractA new extended pollen and charcoal record is presented from Lake Euramoo, Wet Tropics World Heritage rainforest of northeast Queensland, Australia. The 8.4-m sediment core taken from the center of Lake Euramoo incorporates a complete record of vegetation change and fire history spanning the period from 23,000 cal yr B.P. to present. The pollen record is divided into five significant zones; 23,000–16,800 cal yr B.P., dry sclerophyll woodland; 16,800–8600 cal yr B.P., wet sclerophyll woodland with marginal rainforest in protected pockets; 8600–5000 cal yr B.P., warm temperate rainforest; 5000–70 cal yr B.P., dry subtropical rainforest; 70 cal yr B.P.–AD 1999, degraded dry subtropical rainforest with increasing influence of invasive species and fire.The process of rainforest development appears to be at least partly controlled by orbital forcing (precession), though more local environmental variables and human activity are also significant factors. This new record provides the opportunity to explore the relationship between fire, drought and rainforest dynamics in a significant World Heritage rainforest region.

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