Postglacial vegetation history of Orcas Island, northwestern Washington

2016 ◽  
Vol 85 (3) ◽  
pp. 380-390 ◽  
Author(s):  
Estella B. Leopold ◽  
Peter W. Dunwiddie ◽  
Cathy Whitlock ◽  
Rudy Nickmann ◽  
William A. Watts
Keyword(s):  
Plant Communities ◽  
Vegetation History ◽  
Warming Trend ◽  
Tsuga Heterophylla ◽  
Alnus Rubra ◽  
Pollen Record ◽  
Narrow Channels ◽  
San Juan Islands ◽  
Alnus Viridis ◽  
History Of

The revegetation of islands following retreat of Pleistocene glaciers is of great biogeographical interest. The San Juan Islands, Washington, feature regionally distinctive xerophytic plant communities, yet their vegetation history, as it relates to past climate and sea level, is poorly known. We describe a 13,700-year-old pollen record from Killebrew Lake Fen and compare the vegetation reconstruction with others from the region. The data suggest that the narrow channels surrounding Orcas Island were not a barrier to early postglacial immigration of plants. Between 13,700 and 12,000 cal yr BP, Pinus, Tsuga, Picea, Alnus viridis, and possibly Juniperus maritima were present in a mosaic that supported Bison antiquus and Megalonyx. The rise of Alnus rubra-type pollen and Pteridium spores at ca. 12,000 cal yr BP suggests a warming trend and probably more fires. Temperate conifer taxa, including Cupressaceae, Pseudotsuga, Tsuga heterophylla, and Abies, increased after 11,000 cal yr BP and especially in the last 7000 cal yr BP. After 6000 cal yr BP, Pseudotsuga and Cupressaceae dominated the vegetation. The last 1500 yr were the wettest period of the record. Due to its rain shadow location, Orcas Island experienced drier conditions than on the mainland during most of the postglacial period.

A 14,000 year vegetation history of a hypermaritime island on the outer Pacific coast of Canada based on fossil pollen, spores and conifer stomata

2012 ◽  
Vol 78 (3) ◽  
pp. 572-582 ◽  
Author(s):  
Terri Lacourse ◽  
J. Michelle Delepine ◽  
Elizabeth H. Hoffman ◽  
Rolf W. Mathewes
Keyword(s):  
Pinus Contorta ◽  
Vegetation History ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Thuja Plicata ◽  
North Coast ◽  
Pollen Record ◽  
The North ◽  
History Of ◽  
Local Species

AbstractPollen and conifer stomata analyses of lake sediments from Hippa Island on the north coast of British Columbia were used to reconstruct the vegetation history of this small hypermaritime island. Between 14,000 and 13,230 cal yr BP, the island supported diverse herb–shrub communities dominated by Cyperaceae, Artemisia and Salix. Pinus contorta and Picea sitchensis stomata indicate that these conifers were present among the herb–shrub communities, likely as scattered individuals. Transition to open P. contorta woodland by 13,000 cal yr BP was followed by increases in Alnus viridis, Alnus rubra and P. sitchensis. After 12,000 cal yr BP, Pinus-dominated communities were replaced by dense P. sitchensis and Tsuga heterophylla forest with Lysichiton americanus and fern understory. Thuja plicata stomata indicate that this species was present by 8700 cal yr BP, but the pollen record suggests that its populations did not expand to dominate regional rainforests, along with Tsuga and Picea, until after 6600 cal yr BP. Conifer stomata indicate that species may be locally present for hundreds to thousands of years before pollen exceed thresholds routinely used to infer local species arrival. When combined, pollen and conifer stomata can provide a more accurate record of paleovegetation than either when used alone.

Postglacial vegetation history of Mitkof Island, Alexander Archipelago, southeastern Alaska

2010 ◽  
Vol 73 (2) ◽  
pp. 259-268 ◽  
Author(s):  
Thomas A. Ager ◽  
Paul E. Carrara ◽  
Jane L. Smith ◽  
Victoria Anne ◽  
Joni Johnson
Keyword(s):  
Pinus Contorta ◽  
Vegetation History ◽  
Regional Climate ◽  
Sitka Spruce ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Thuja Plicata ◽  
Pollen Record ◽  
Coastal Forests ◽  
History Of

An AMS radiocarbon-dated pollen record from a peat deposit on Mitkof Island, southeastern Alaska provides a vegetation history spanning ∼12,900 cal yr BP to the present. Late Wisconsin glaciers covered the entire island; deglaciation occurred > 15,400 cal yr BP. The earliest known vegetation to develop on the island (∼12,900 cal yr BP) was pine woodland (Pinus contorta) with alder (Alnus), sedges (Cyperaceae) and ferns (Polypodiaceae type). By ∼12,240 cal yr BP, Sitka spruce (Picea sitchensis) began to colonize the island while pine woodland declined. By ∼11,200 cal yr BP, mountain hemlock (Tsuga mertensiana) began to spread across the island. Sitka spruce-mountain hemlock forests dominated the lowland landscapes of the island until ∼10,180 cal yr BP, when western hemlock (Tsuga heterophylla) began to colonize, and soon became the dominant tree species. Rising percentages of pine, sedge, and sphagnum after ∼7100 cal yr BP may reflect an expansion of peat bog habitats as regional climate began to shift to cooler, wetter conditions. A decline in alders at that time suggests that coastal forests had spread into the island's uplands, replacing large areas of alder thickets. Cedars (Chamaecyparis nootkatensis, Thuja plicata) appeared on Mitkof Island during the late Holocene.

scholarly journals Late Miocene Vegetational History of Jackson Hole, Wyoming

1980 ◽  
Vol 4 ◽  
pp. 28-31
Author(s):  
C. Barnosky
Keyword(s):  
Plant Communities ◽  
Regional Scale ◽  
Pollen Record ◽  
Regional Patterns ◽  
Sufficient Detail ◽  
Dominant Feature ◽  
Community Evolution ◽  
Jackson Hole ◽  
History Of ◽  
Fossil Floras

The frequent reassortment of angiosperms to form new communities, a dominant feature of the Quaternary record, has seldom been recognized in earlier periods. In fact, analysis of fossil floras in North America suggests that Tertiary plant communities were relatively stable over long periods of time (for example, Hickey, 1977; MacGinitie, 1969; Wolfe, 1975). This stability suggests that either the record has not been studied in sufficient detail or that the factors controlling plant and environment interactions were less variable than in the Quaternary. If the latter hypothesis is true, the botanical record of the last 1.8x 10^6 yr may be an atypical model on which to base our understanding of community evolution . To assess the importance of short-term variation in Tertiary plant communities, detailed botanical analyses of continuous stratigraphic sections are needed. In particular, a pollen record through a lacustrine sequence is critical for recognizing rapid, floristic or vegetational changes on a regional scale. Thus far, such recognition has been difficult because our understanding of floristic development is based primarily on plant megafossils. While such material provides information on the riparian flora adjacent to a depositional site, it reveals little about regional patterns.

scholarly journals Zur Pollenanalyse von Lössen: Untersuchungen der Lößprofile von Oberfellabrunn und Stillfried (Niederösterreich)

1964 ◽  
Vol 15 (1) ◽  
pp. 5-39
Author(s):  
Burkhard Frenzel
Keyword(s):  
Plant Communities ◽  
Vegetation History ◽  
Northern Eurasia ◽  
Loamy Soil ◽  
Plant Associations ◽  
Surface Samples ◽  
Last Glaciation ◽  
Steppe Communities ◽  
History Of ◽  
Eemian Interglacial

Abstract. A method for pollenanalytical investigations of loesses is described. If several sources of error are duely taken into consideration, this method is successful in the reconstruction of the vegetation history of those phases of pleniglacial times, during which the thick loess layers were accumulated. The method can be employed in pollenanalytical investigations of weathered and unweathered loesses, with the exception of redeposited loesses. It can be shown that the famous sequence of fossil soils at Oberfellabrunn, known as the soils of the "Fellabrunner Komplex" („Stillfried A"), which is sometimes held to be the equivalent of the "Göttweig Interstadial", must be divided into the brown loamy soil at the base of the sequence, which was formed during the Eemian Interglacial, and into the younger humic layers, which developed during the Interstadials of Amersfoort and Brørup. The amelioration of climate during the "Stillfried B-Interstadial" (perhaps equivalent of the "Paudorf Interstadial"?) was strong enough to enable local subalpine conifer forests and riverine broad-leaved forests to spread along the rivers and other suitable places within the still dominant steppe formations on the drier loess plateaus. The loess layers of the Riss and Würm glaciations have been accumulated within the eastern Dart of Niederösterreich in different steppe communities, which can be described at best as belonging to the Gramineae steppe formation, rich in herbaceous plants. Sometimes there occurred plants of recent tundra-communities in the loess steppe: but real tundras did not exist at that time in Niederösterreich. This holds true most of all for the last period of loess accumulation after the Stillfried B-Interstadial. When being compared with pollen spectra of surface samples of recent tundra, steppe and semidesert plant communities, it becomes evident, that the open vegetation, thriving during the last glaciation in vast regions of Northern Eurasia cannot be described in terms of modern plant associations.

scholarly journals Vegetation and climate dynamics in Khyber Pakhtunkhwa (NW Pakistan), inferred from the pollen record of the Kabal Valley in Swat District during the last 3300 years

2019 ◽  
Vol 59 (1) ◽  
pp. 145-163
Author(s):  
Farooq Jan ◽  
Lisa Schüler ◽  
Fayaz Asad ◽  
Hermann Behling
Keyword(s):  
Vegetation History ◽  
Agricultural Activity ◽  
Pollen Record ◽  
Conifer Forest ◽  
Khyber Pakhtunkhwa ◽  
Hindu Kush ◽  
History Of ◽  
Khyber Pakhtunkhwa Province ◽  
Trees And Shrubs ◽  
Vegetation And Climate

Abstract We present a pollen-based palaeoenvironmental reconstruction of the past 3300 years in the Kabal Valley of Swat District in the Hindu Kush mountains of Khyber Pakhtunkhwa Province, north-western Pakistan. We studied the pollen record from 38 samples taken from a 150 cm long radiocarbon-dated sediment core in order to analyse the vegetation history of the area. Only the upper 76 cm of the core, with 20 samples recording the last 3300 years, had sufficiently preserved pollen. Conifers such as Pinus, Picea, Abies, Cedrus and Taxus, and herbs belonging to Poaceae, Cyperaceae and Amaranthaceae were found consistently throughout the period, at varying abundance. The vegetation reconstruction revealed that Cyperaceae and Poaceae dominated the conifers from 3300 to 300 cal yr BP. The decrease in herbaceous vegetation (mainly Poaceae) from 2400 to 1500 cal yr BP, and its increase from 1500 to 1200 cal yr BP, indicate contraction followed by expansion of grassland in the Kabal Valley of Swat, pointing to corresponding dry-cool and wet-warm periods. Herbs were abundant in most samples from 900 to 300 cal yr BP. This change from conifer forest to open grassland can be attributed to the more pronounced impact of widespread deforestation, agricultural activity and a drier summer climate. Evergreen trees and shrubs such as Oleaceae, Myrtaceae, Moraceae species, Juglans and Dodonaea dominated and were constant from 2400 cal yr BP to the present. Conifers such as Pinus, Taxus, Picea, Abies and Cedrus were frequent in the study area from 300 cal yr BP to the present. Today these conifers occur mostly in mixed coniferous forests at higher elevation in the alpine area.

Postglacial vegetation history of the Mariana Lake region, Alberta

1994 ◽  
Vol 31 (2) ◽  
pp. 418-425 ◽  
Author(s):  
M. J. Hutton ◽  
G. M. MacDonald ◽  
R. J. Mott
Keyword(s):  
Picea Mariana ◽  
Picea Glauca ◽  
Vegetation History ◽  
Fossil Pollen ◽  
Pollen Record ◽  
Sparse Vegetation ◽  
Lake Region ◽  
History Of

A fossil pollen record extending from 11 300 BP to the present was recovered from Mariana Lake, Alberta (55°57′N, 112°01′W). Initially, the region had a sparse vegetation dominated by forbs and graminoids, which at approximately 10 500 BP succeeded to Picea glauca forest. Picea mariana – Sphagnum peatlands began to develop between 10 000 and 9500 BP. After 9000 BP Sphagnum-dominated sites decreased; P. glauca declined while Betula increased. From 7500 to 5500 BP Populus reached its maximum Holocene representation in the vegetation. Sphagnum-dominated peatlands almost disappeared. The changes following 9000 BP were likely caused by increased aridity. However, the presence of P. mariana, Abies, and Larix in the pollen record suggests that mesic sites remained. Beginning at 6500–6000 BP the extent of Sphagnum peatlands began to increase. Abies declined in importance following 5000 BP, possibly due to paludification of mesic sites. The expansion of parkland into central Alberta during the mid-Holocene did not extend to Mariana Lake. However, Mariana Lake records changes in vegetation resulting from increased aridity in the early to mid-Holocene which are not apparent at more northerly sites in Alberta.

Vegetation History of Pleasant Island, Southeastern Alaska, since 13,000 yr B.P.

1996 ◽  
Vol 46 (2) ◽  
pp. 161-175 ◽  
Author(s):  
Barbara C. S. Hansen ◽  
Daniel R. Engstrom
Keyword(s):  
Vegetation History ◽  
Lodgepole Pine ◽  
Late Quaternary ◽  
Lacustrine Sediments ◽  
Tsuga Heterophylla ◽  
Temperature And Precipitation ◽  
Early Arrival ◽  
Peatland Development ◽  
History Of ◽  
Lake Catchment

A 13,000-year history of late-Quaternary vegetational and climatic change has been derived from lacustrine sediments from Pleasant Island in the Glacier Bay region of southeastern Alaska. Early arrival of lodgepole pine and mountain hemlock, indicated by the presence of pollen and conifer stomata, suggests expansion from refugia in the Alexander Archipelago. A short-term climatic reversal, possibly correlated with the European Younger Dryas, is inferred from the expansion of tundra elements and deposition of inorganic sediments between 10,600 and 9900 14C yr B.P. Two peat cores from the lake catchment verify Holocene vegetation changes and aid in the separation of biogenic from climatic forces affecting vegetation history. Differences in pollen representation among the three cores illustrate the variation among pollen-collecting substrates, as well as the spatial heterogeneity of peatland development and its dependence on local hydrology. Initial peat accumulation and soil paludification, occasioned by increases in temperature and precipitation in the early Holocene, allowed western and mountain hemlock to replace sitka spruce 8500–8000 yr B. P. Open muskeg became widespread about 7000 yr B. P. and allowed lodgepole pine to reinvade the region after a 2000-yr absence. The extensive replacement of fen elements by bog taxa at 3400 yr B. P. suggests increased paludification due to changing hydrologic conditions; its correlation with the upland expansion of Tsuga heterophylla suggests the onset of a cooler/wetter Neoglacial climate in southeastern Alaska.

Holocene history of a raised bog, northern New Zealand, based on plant cuticles

The Holocene ◽  
2016 ◽  
Vol 27 (2) ◽  
pp. 309-314 ◽  
Author(s):  
Carolin Haenfling ◽  
Rewi Newnham ◽  
Andrew Rees ◽  
Ignacio Jara ◽  
Aline Homes ◽  
...  
Keyword(s):  
New Zealand ◽  
Vegetation History ◽  
Pollen Grains ◽  
Plant Cuticle ◽  
Pollen Record ◽  
Raised Bog ◽  
Local Site ◽  
Pollen Types ◽  
Plant Cuticles ◽  
History Of

We present a method for analysing subfossil plant cuticles preserved in peat and apply the method to provide a preliminary, coarse resolution reconstruction of Holocene vegetation history at Moanatuatua Bog, northern North Island, New Zealand. The plant cuticle record reveals the early-Holocene development of a swamp and its transition to a raised bog, which is not apparent from other proxies. Comparison with a pollen record from the same sequence highlights the advantages of plant cuticle analysis in cases where pollen is hard to identify or poorly preserved. In particular, distinguishing between the pollen grains of the two main bog species, the restiads Empodisma robustum and Sporadanthus ferrugineus, relies on subtle gradational characteristics, whereas their cuticular patterns are very distinct. Furthermore, Cyperaceae pollen is poorly preserved at Moanatuatua Bog, being almost completely absent, whereas the Cyperaceae cuticles are present throughout the sequence. Therefore, we suggest that Cyperaceae pollen at this site is a less reliable indicator of local sedge communities than the cuticle record. The wide dispersal capabilities of these wind-dispersed pollen types also make them less suitable for determining local site vegetation and environmental change in comparison with cuticle remains. These results suggest that plant cuticle analysis may be a useful tool for the reconstruction of long-term vegetation changes from peat sequences, especially when used in concert with palynology. Sample preparation also proved to be fast with little equipment or chemicals needed.

scholarly journals Late-Quaternary Vegetation History of Jackson Hole, Wyoming

1982 ◽  
Vol 6 ◽  
pp. 35-36
Author(s):  
Cathy Barnosky
Keyword(s):  
Environmental History ◽  
Plant Communities ◽  
Rocky Mountains ◽  
Vegetation History ◽  
Late Quaternary ◽  
Sediment Cores ◽  
Northern Rocky Mountains ◽  
Hole Area ◽  
Jackson Hole ◽  
History Of

During the late Quaternary, the Jackson Hole area has reen repeatedly glaciated-the most recent and least extensive ice advance occurred during the Pinedale Glaciation (ca. 25,000-9,000 yr B.P.; Love and Reed, 1971). The objective of this research is to study the vegetation history of Jackson Hole since Pinedale time, as a means of interpreting the development and stability of modern plant communities. The research is based on an examination of pollen and plant-macrofossiil records contained in lake-sediment cores collected near the former ice margin. The environmental history of this region is poorly known and the paleoecological information provided by this study should help fill a gap in our understanding of the vegetation, climate, and glacial history of the Northern Rocky Mountains.

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