Holocene vegetation history of Banks Island, Northwest Territories, Canada

2000 ◽  
Vol 78 (4) ◽  
pp. 430-436 ◽  
Author(s):  
K Gajewski ◽  
R J Mott ◽  
J C Ritchie ◽  
K Hadden
Keyword(s):  
Northwest Territories ◽  
Vegetation History ◽  
Middle Zone ◽  
Pollen Diagram ◽  
Radiocarbon Dates ◽  
Banks Island ◽  
Pollen Diagrams ◽  
Pollen Types ◽  
History Of ◽  
Lower Frequencies

Four pollen diagrams from Banks Island, Northwest Territories, provide the first records of the postglacial vegetation of the region. Chronologies are estimated from radiocarbon dates and by correlation of the exotic-pollen curves to data from the mainland. The pollen stratigraphies from all sites can be divided into three zones, where the middle zone, dating from 7000 to 2000 BP, corresponds to the warmest time. Although both the first and third zones correspond to cooler periods, the vegetation of the earliest zone was not identical to that of the latest, indicated by lower frequencies of key pollen types such as those of Dryas and Saxifraga.Key words: Banks Island, Holocene, pollen diagram, Arctic, paleoecology, Quaternary.

Holocene vegetation history of Banks Island, Northwest Territories, Canada

2000 ◽  
Vol 78 (4) ◽  
pp. 430-436 ◽  
Author(s):  
K. Gajewski ◽  
R.J. Mott ◽  
J.C. Ritchie ◽  
K. Hadden
Keyword(s):  
Northwest Territories ◽  
Vegetation History ◽  
Banks Island ◽  
History Of

A Vegetation History of the Far North of New Zealand during the Late Otira (Last) Glaciation

1993 ◽  
Vol 39 (3) ◽  
pp. 361-372 ◽  
Author(s):  
Rewi Newnham ◽  
John Ogden ◽  
Dallas Mildenhall
Keyword(s):  
New Zealand ◽  
Forest Cover ◽  
Vegetation History ◽  
Mixed Forest ◽  
Radiocarbon Dates ◽  
Substantial Loss ◽  
Far North ◽  
Last Glaciation ◽  
Pollen Diagrams ◽  
History Of

AbstractDuring the latter part of the last (Otira) glaciation the forest cover of New Zealand was much reduced. It has frequently been postulated, however, that diverse mixed forest communities survived in the far north of North Island. Pollen diagrams and radiocarbon dates from two last glacial and postglacial (Aranuian) sits on the Aupouri Peninsula in the far north of New Zealand are compared with other published palynological and plant macrofossil evidence from the region. Mixed kauri/podocarp/angiosperm forest was present at times during the late Otiran (and Aranuian) and no evidence was found for substantial loss of forest. However, radiocarbon samples from one site, at least, seem to have been contaminated with young carbon; this introduces uncertainty into the chronology established at that site. Possibly nondeposition or erosion has obscured part or all of the late Otiran record at all the sites studied so that very much reduced forest cover at that time cannot be ruled out.

A palynological study of postglacial vegetation changes in the University Research Forest, southwestern British Columbia

1973 ◽  
Vol 51 (11) ◽  
pp. 2085-2103 ◽  
Author(s):  
Rolf W. Mathewes
Keyword(s):  
British Columbia ◽  
Pinus Contorta ◽  
Vegetation Change ◽  
Vegetation History ◽  
Sediment Cores ◽  
Silty Clay ◽  
Pollen Diagram ◽  
History Of ◽  
Palynological Study ◽  
The University

The postglacial vegetation history of the University of British Columbia Research Forest was investigated using percentage and absolute pollen analysis, macrofossil analysis, and radiocarbon dating. A marine silty clay deposit records the oldest (12 690 ± 190 years before present (B.P.)) assemblage of terrestrial plant remains so far recovered from the postglacial of south-coastal British Columbia. Lodge-pole pine (Pinus contorta) dominated this early vegetation, although some Abies, Picea, Alnus, and herbs were also present. Sediment cores from two lakes were also studied. The older is Marion Lake, where five pollen assemblage zones are recognized, beginning with a previously undescribed assemblage of Pinus contorta, Salix, and Shepherdia in clay older than 12 350 ± 190 B.P. The pollen diagram from Surprise Lake (11 230 ± 230 B.P.) is divided into three pollen zones which show the same major trends of vegetation change as the Marion Lake diagram.The first report of the postglacial vegetation history of cedar (Thuja and perhaps Chamaecyparis) in southwestern British Columbia is presented from pollen and macrofossil analyses.At about 10 500 B.P. in both lakes, pollen of Douglas fir (Pseudotsuga menziesii) began a rapid increase, probably in response to climatic amelioration. The palynological evidence, supported by well-preserved bryophyte subfossils, suggests that humid coastal conditions have prevailed in the study area since about 10 500 B.P., with virtually no evidence for a classical Hypsithermal interval between 8500 B.P. and 3000 B.P.

The interpretation of some post-Glacial vegetation diversities at different Lake District sites

1965 ◽  
Vol 161 (984) ◽  
pp. 310-323 ◽  
Keyword(s):  
Lake Sediments ◽  
Drainage Basin ◽  
Large River ◽  
Single Type ◽  
Lake District ◽  
Drainage Basins ◽  
Radiocarbon Dates ◽  
Pollen Diagrams ◽  
History Of ◽  
The Individual

The lake sediments which have been described by Mr Mackereth contain pollen and other plant remains which record the broad outlines of vegetational history. Many pollen diagrams are now available from the one ecologically homogeneous area of the central Lake District; their similarities record the effects of a single type of climate on an area of uniformly ancient rock, while their diversities record the individual history of each drainage basin. The large river valley lakes such as Windermere represent an integration of the many small drainage basins of which the river systems are made up; a simpler ecological picture is presented by the small lakes or tarns. Mackereth’s hypothesis, based on purely chemical evidence, that the lake sediments are derived from a series of soils washed in from the drainage basins, is supported by all the pollen evidence. Two deductions are made from this accepted assumption—first, that radiocarbon assay of the lake muds would be of comparatively little value, since the organic matter in any sample may have originated from a soil and be much older than its date of incorporation in the lake mud, and secondly that the presence of derived pollen from soils must be considered in interpretation of the pollen diagrams. The outline of the ecological history of the Lake District attempted here must therefore be built up by synthesis and comparison, but, as yet, in the absence of radiocarbon dates. The advantages of lake sediments for post-Glacial investigation—to set against their limitations—are that there is no overwhelming local pollen component as in fen or bog peats, and that stratigraphical changes in the sediments provide evidence for major changes in erosion rate, which can be correlated with vegetation changes shown in the pollen diagrams—as can chemical changes related to soil changes in the drainage basins.

Late Quaternary vegetation history of the central Mackenzie Mountains, Northwest Territories, Canada

1995 ◽  
Vol 113 (2-4) ◽  
pp. 351-371 ◽  
Author(s):  
Julian M. Szeicz ◽  
Glen M. MacDonald ◽  
Alejandra Duk-Rodkin
Keyword(s):  
Northwest Territories ◽  
Vegetation History ◽  
Late Quaternary ◽  
History Of ◽  
Mackenzie Mountains

Holocene Vegetation History of the Prince William Sound Region, South-Central Alaska

1983 ◽  
Vol 19 (3) ◽  
pp. 337-355 ◽  
Author(s):  
Calvin J. Heusser
Keyword(s):  
Vegetation History ◽  
Influential Factor ◽  
Tectonic Activity ◽  
Prince William Sound ◽  
Sedimentary Records ◽  
South Central ◽  
Peat Deposits ◽  
Pollen Diagrams ◽  
History Of ◽  
Fossil Records

AbstractVegetation history during the Holocene is interpreted from the pollen and sedimentary records of nine sections of peat deposits located in sedge tundra at sites in the northern and northwestern parts of the Prince William Sound region. Basal radiocarbon ages of the deposits are between 10,015 and 580 yr B.P. Modern surface pollen data from these and 25 additional sites, ranging from lowlands to an altitude of 675 m in the alpine tundra, were used to aid in the interpretation of the fossil records. Both frequency and influx pollen diagrams of the oldest section disclose a sequence of communities beginning with sedge tundra, containing thickets of willow and alder, followed by alder, which became predominant at about 8300 yr B.P. Later, alder declined, and an inferred growth of sedge tundra and the establishment of colonies of mountain hemlock and Sitka spruce with some western hemlock occurred about 2680 yr B.P. Finally, regrowth of sedge tundra accompanied by the development of forest communites took place over the past 2000 yr. The influence of glacier advances on the vegetation in the fjords occurred during Neoglacial episodes dated at 3200–2500 yr B.P. and during recent centuries. Regional Holocene tectonic activity was also an influential factor, especially at the time of the 1964 earthquake.

Development of a peatland complex in boreal western Canada: lateral site expansion and local variability in vegetation succession and long-term peat accumulation

2003 ◽  
Vol 81 (8) ◽  
pp. 833-847 ◽  
Author(s):  
Ilka E Bauer ◽  
L Dennis Gignac ◽  
Dale H Vitt
Keyword(s):  
Vegetation History ◽  
Community Change ◽  
Vegetation Succession ◽  
Peat Accumulation ◽  
Radiocarbon Dates ◽  
Nucleation Sites ◽  
Peatland Development ◽  
Water Tables ◽  
History Of

The spatial development and vegetation history of a large boreal peatland complex in east-central Alberta was reconstructed to examine factors that control peatland development in continental regions. Peat depth throughout the site was interpolated from over 300 depth measurements, and basal radiocarbon dates were obtained from 16 cores. Peat first initiated about 7400 calibrated 14C years BP (cal. BP), and early peat-forming communities were wet fens or marshes. Rates of expansion from these nucleation sites were dependent on both moisture availability and topography, with asynchronous expansion in different regions. Basal macrofossil assemblages suggest that paludification on slopes of large basins was the result of flooding caused by rising peatland water tables. In many areas that initiated after 3000 cal. BP, paludification involved invasion of upland forest by Sphagnum. Long-term apparent rates of peat accumulation were fastest in wet, moderate-rich fen areas where little community change has occurred over time. Macrofossil analysis of core profiles reveals a tendency for sites that initiated wet and minerotrophic to eventually be colonized by Sphagnum. However, the thickness of surficial Sphagnum layers differs between cores, and there are several examples of minimal or apparently reverse successional development.Key words: peatlands, boreal, paleoecology, vegetation succession, peat accumulation, paludification.

Late Quaternary vegetation history of Kettlehole Pond, southwestern Yukon

1988 ◽  
Vol 18 (10) ◽  
pp. 1270-1279 ◽  
Author(s):  
Les C. Cwynar
Keyword(s):  
Vegetation History ◽  
Late Quaternary ◽  
Initial Period ◽  
Forest Tree ◽  
Published Data ◽  
Vegetation Changes ◽  
Pollen Diagram ◽  
Mesic Forest ◽  
Effective Moisture ◽  
History Of

A pollen diagram with a detailed chronology reveals Late-Pleistocene and Holocene vegetation changes which, in combination with previously published data, provide information on regional vegetation changes in the western boreal forest of the southwestern Yukon. A Populus woodland with an understory of Shepherdiacanadensis and extensive open areas dominated by Artemisia occurred from 11 030 to 9250 BP. Juniperus populations expanded at 9700 BP and then more-mesic forest communities developed when Piceaglauca populations increased at 9250 BP and Populus declined. At 6100 BP there is a remarkable shift from Piceaglauca woodland with Juniperus to a mixed spruce forest in which P. mariana was the dominant species. At 4100 BP conditions altered to favour P. glauca which expanded at the expense of P. mariana, and Juniperus again became important in the vegetation. By 1900 BP Pinuscontorta had become a dominant tree as P. mariana declined, the latter eventually disappearing from the local vegetation. There is no evidence that grasslands were more extensive in the early Holocene, as has been hypothesized for the southwestern Yukon. The vegetation sequence implies an initial period of aridity from 11 030 to 9250 BP, when summer warmth was probably greater than that of the modern climate, a period of increased effective moisture between 9250 and 6100 BP, when Piceaglauca was abundant, even greater effective moisture between 6100 and 4100 BP, when Piceamariana was the dominant forest tree, and then a prolonged period of increasing aridity beginning at 4100 BP and culminating in the development of the modern semi-arid climate.

scholarly journals Medieval impacts on the vegetation around the confluence of the river Meuse and its tributary the Swalm, the Netherlands

2016 ◽  
Vol 96 (2) ◽  
pp. 165-173 ◽  
Author(s):  
Corrie Bakels
Keyword(s):  
The Netherlands ◽  
Middle Ages ◽  
Large Scale ◽  
Vegetation History ◽  
Black Death ◽  
Anthropogenic Stress ◽  
River Meuse ◽  
Pollen Diagrams ◽  
History Of ◽  
The Middle Ages

AbstractThe vegetation history of the area around the confluence of the rivers Meuse and Swalm (the Netherlands) during the Middle Ages is covered by two pollen diagrams. The diagram Swalmen reveals a large-scale deforestation as a result of the foundation of a nobleman's homestead around 950. The diagram Syperhof shows a period during which the forest partly returns after a long history of unremitting anthropogenic stress. This temporary phenomenon is ascribed to the onslaught of the Black Death in 1349. Both diagrams provide evidence of the start of buckwheat growing.

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.

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