An 18 ka to present pollen- and phytolith-based vegetation reconstruction from Hall's Cave, south-central Texas, USA

2019 ◽  
Vol 92 (2) ◽  
pp. 497-518 ◽  
Author(s):  
Carlos E. Cordova ◽  
William C. Johnson
Keyword(s):  
Vegetation Change ◽  
Last Deglaciation ◽  
Sedimentary Records ◽  
South Central ◽  
Drought Tolerant ◽  
Arboreal Pollen ◽  
Central Texas ◽  
Scattered Trees ◽  
Sizable Proportion ◽  
Drying Trend

AbstractPollen, spores, phytoliths, and microscopic charcoal from a sedimentary column in Hall's Cave, south-central Texas, provide information for local and regional vegetation change during the last deglaciation and the Holocene in the context of broader regional and global climatic changes. The combination of paleoenvironmental proxy data from the cave indicates that between about 18,000 and 16,500 cal yr BP the cave area was dominated by an open plant community consisting of herbaceous vegetation, dominated by C3 grasses, and scattered trees, primarily Quercus and Pinus species. After about 16,500 cal yr BP, the arboreal component fluctuated, attaining a peak between 14,000 and 13,000 cal yr BP with relatively equal proportions of C3 and C4 grasses, including a sizable proportion of Panicoideae grasses. The Younger Dryas is marked by a conspicuous decrease in arboreal pollen with an apparent increase of C4 grasses toward its termination. Early Holocene recovery of arboreal vegetation is followed by a drying trend marked by the increasing dominance of C4 drought-tolerant Chloridoideae grasses. Increasing human use of the cave in middle to late Holocene times creates noise in the climatic significance of pollen, phytolith, and other proxies, a factor to consider when interpreting paleoenvironmental proxies in other cave sedimentary records.

Paleoclimate Changes during the last 100,000 yr from a Record in the Brazilian Atlantic Rainforest region and Interhemispheric Comparison

2005 ◽  
Vol 64 (3) ◽  
pp. 444-450 ◽  
Author(s):  
M.-P. Ledru ◽  
D.-D. Rousseau ◽  
F.W. Cruz ◽  
C. Riccomini ◽  
I. Karmann ◽  
...  
Keyword(s):  
Global Climate ◽  
Ice Core ◽  
Climatic Changes ◽  
Climate Forcing ◽  
Atlantic Rainforest ◽  
Tropical Atlantic ◽  
Forest Expansion ◽  
Last Glaciation ◽  
Arboreal Pollen ◽  
Brazilian Atlantic Rainforest

AbstractA long terrestrial record, Colônia CO-3, from the Atlantic rainforest region in Brazil (23°52′S, 46°42′20 ʺW, 900 m a.s.l.) registrates variations in the forest expansion during the last 100,000 yr. The 780-cm depth core was analyzed at 2-cm intervals and arboreal pollen frequencies were compared to nearby speleothem stable isotope records and neighboring marine records from the tropical Atlantic. To evaluate regional versus global climate forcing, our record was compared with Greenland and Antarctic ice-core records. These comparisons suggest that changes in temperature seen in polar latitudes relate to moisture changes: e.g., to changes in the length of the dry season, in tropical and subtropical latitudes during glacial as well as interglacial times. These climatic changes result from changes in the frequency of polar air incursions to these latitudes inducing a permanent cloud cover and precipitation. This is an important result that should help define paleoclimatic features in the Southern Hemisphere for the last glaciation.

Pollen Analysis of Digger's Creek Bog, Kosciuszko National Park: Vegetation History and Tree-line Change

1999 ◽  
Vol 47 (5) ◽  
pp. 725 ◽  
Author(s):  
A. R. H. Martin
Keyword(s):  
National Park ◽  
Vegetation History ◽  
Early 20Th Century ◽  
Peat Bog ◽  
Tree Line ◽  
Before Present ◽  
Near Surface ◽  
Lake Zone ◽  
Arboreal Pollen ◽  
Eastern Australia

Digger's Creek Bog, an Empodisma minus–Callistemon pityoides–Sphagnum cristatum shrubby subalpine peat bog, alt. c. 1690 m, not far below local altitudinal tree-line, began development > 10 000 years before present as an Astelia sp.–Carex alpine soak. Surrounding vegetation was a grassy alpine herbfield with many Asteraceae, Apiaceae and Gentianella diemensis, corresponding to the regional Club Lake Zone C, dated to the same period. Astelia died out c. 6500 years before present approximately at the Club Lake C/D 1 boundary, marked by spread of Pomaderris in subjacent montane forests. Thereafter, shrubs, mainly Myrtaceae and Epacridaceae, and Restionaceae (Empodisma and Restio australis) dominated the bog. Epacris cf. paludosa and C. pityoides seem to have been the earliest shrubs to invade, Baeckea, probably B. gunniana, and Richea continentis reaching maximum prominence 5000–3000 years before present. Sphagnum was uncommon until recently. Regional arboreal pollen enable comparisons with other sites in south-eastern Australia but immigration of the tree-line species Eucalyptus pauciflora subsp. niphophila (snowgum) is not well expressed in the pollen spectra. Surface and near-surface counts of this species are higher than at any preceding time, and correspond most closely to surface counts in adjacent young snowgum woodland. The co-occurrence of weed pollens, probably associated with the late 19th and early 20th century practice of summer pasturing stock on the alpine–subalpine tract, suggests that pasturing and burning, responsible for widespread severe fires on this range, led both to the formation of dense even-aged snowgum woodland that had been open and patchy at this altitude, and a spread of Sphagnum on the bog surface.

Analysis of airborne pollen fall in Sakarya, Turkey

Biologia ◽  
2006 ◽  
Vol 61 (4) ◽  
Author(s):  
Adem Bicakci
Keyword(s):  
Airborne Pollen ◽  
Pollen Grains ◽  
Arboreal Pollen ◽  
Total Pollen

AbstractIn this study, pollen grains were identified using Durham sampler in the atmosphere of Sakarya in 2000 and 2001. During these two years, a total of 10 805 pollen grains were recorded. A total of 5 386 pollen grains per cm2 were recorded in 2000 and a total of 5 419 pollen grains per cm2 in 2001. Pollen fall in the years 2000–2001 comprised grains belonging to 40 taxa and some unidentified pollen grains. Of these taxa, 22 belonged to arboreal and 18 taxa to non arboreal plants. Total pollen grains consisted of 69.45% grains from arboreal plants, 28.11% grains from non-arboreal plants and 2.44% unidentified pollen grains. In the region investigated, Gramineae, Pinus sp., Quercus sp., Cupressaceae/Taxaceae, Salix sp., Platanus sp., Populus sp., Carpinus sp., Fagus sp., Chenopodiaceae/Amaranthaceae, Xanthium sp., Moraceae, Corylus sp., Fraxinus sp., and Urticaceae released the greatest amount of pollen. The season of maximum pollen fall was from March to May, with a prevalence of arboreal pollen in the first months, and of pollen from non-arboreal plants in the last months of the year.

Modern pollen spectra from lakes in arctic western Canada

1987 ◽  
Vol 65 (8) ◽  
pp. 1605-1613 ◽  
Author(s):  
J. C. Ritchie ◽  
K. A. Hadden ◽  
K. Gajewski
Keyword(s):  
Late Glacial ◽  
High Arctic ◽  
Pollen Deposition ◽  
Tree Pollen ◽  
Indicator Taxa ◽  
Modern Pollen ◽  
Banks Island ◽  
Arboreal Pollen ◽  
Low Arctic ◽  
Trees And Shrubs

Fifty-four samples of modern sediment from Banks Island and the Melville–Horton region of the Northwest Territories illustrate the major features of pollen deposition from the high to low arctic. Modern pollen deposition in the high arctic of Banks Island is characterized by up to 14% windblown tree pollen. Indicator taxa of the high and mid arctic include Oxyria (<5–23%), Saxifragaceae, Saxifraga oppositifolia, and Cruciferae (all up to 8%) and Dryas (up to 3%). Arboreal pollen increases to 60% in low-arctic and subarctic samples. Pollen concentration decreases from between 3 500 and 20 000 in the low arctic to less than 5 000 grains/cm3 in the high and mid arctic. Pollen spectra from the Late Glacial of northwestern Canada differ from those of the modern high and mid arctic not only by the absence of trees and shrubs but also in the relative proportions of Artemisia and of such indicator taxa as Oxyria and Saxifragaceae.

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