History of the endangered thread-leaved sundew (Drosera filiformis) in southern Nova Scotia

2005 ◽  
Vol 83 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Mark Landry ◽  
Les C Cwynar
Keyword(s):  
Nova Scotia ◽  
Residence Time ◽  
Radiocarbon Dating ◽  
Plant Macrofossil ◽  
Radiocarbon Age ◽  
Macrofossil Analysis ◽  
The Past ◽  
History Of ◽  
Minimum Residence Time ◽  
Plant Macrofossil Analysis

We used the techniques of plant macrofossil analysis and radiocarbon dating to determine the minimum residence time of the endangered thread-leaved sundew (Drosera filiformis Raf.) in three bogs of southern Nova Scotia. The minimum residence times are 4240 cal. year BP for Swain's Road Bog, 2050 cal. year BP for Villagedale Bog, and very recent (modern radiocarbon age) for Port La Tour Bog, indicating that the species has likely been in the region for the past 4240 years. Analysis of nearby Old School Road Bog, which lacks D. filiformis today, failed to find any evidence that it formerly occurred there, suggesting that it may not have been more widespread in the past than it is today.Key words: Drosera filiformis, thread-leaved sundew, plant macrofossil analysis, radiocarbon dating, bogs, minimum residence time.

Forest history of the last 12 000 years based on plant macrofossil analysis of sediment from Marion Lake, southwestern British Columbia

1987 ◽  
Vol 65 (11) ◽  
pp. 2179-2187 ◽  
Author(s):  
Newton Wainman ◽  
Rolf W. Mathewes
Keyword(s):  
British Columbia ◽  
Forest History ◽  
Thuja Plicata ◽  
Taxus Brevifolia ◽  
Good Correspondence ◽  
Plant Macrofossil ◽  
Macrofossil Analysis ◽  
Red Cedar ◽  
High Runoff ◽  
Plant Macrofossil Analysis

The forest history around Marion Lake in southwestern British Columbia is reconstructed using plant macrofossil analysis. A comparison with a previous reconstruction based on pollen and spore analysis reveals a good correspondence between pollen and macrofossil zones. Significant improvements in the reconstruction of forest history are possible by combining the study of pollen and macrofossils. Thuja plicata macrofossils do not appear at Marion Lake until 6000 BP, contradicting previous suggestions of red cedar presence as early as 10 000 BP. Although not common at present, Taxus brevifolia may have been an important component of the forest prior to the arrival of Thuja. Fluvial input of macrofossils is important at Marion Lake. Charcoal also appears to enter the lake primarily during periods of high runoff and erosion in the watershed, suggesting the need for caution in the interpretation of charcoal data from stream-fed lakes. Increases in total influx coincide with evidence for increased precipitation after 7000 BP. Marked reductions in macrofossil influx coincide with periods of peat deposition upstream from the present lake. Relative percentages of conifer needles are unaffected by changes in influx.

Bertrand Russell (1872-1970) after twenty years

1990 ◽  
Vol 44 (2) ◽  
pp. 280-306 ◽  
Keyword(s):  
Nova Scotia ◽  
Historical Research ◽  
Bertrand Russell ◽  
British History ◽  
Arithmetical Property ◽  
The Past ◽  
History Of ◽  
The Subject ◽  
Long Life ◽  
The Many

1990 marks the vicesenary of the death of Bertrand Russell, in his 98th year; and this arithmetical property is sufficient reason to review the historical research that has been published on his life and work during the past 20 years. During his long life he had already become the subject of historical research in many of his activities; but this interest accelerated considerably around the time of his death because in the mid 1960s he had decided to sell the bulk of his manuscripts, to raise money to finance his current projects. One of these was the series of conferences financed by the Canadian industrialist Cyrus Eaton, which began at his birthplace of Pugwash, in Nova Scotia. An alumnus of McMaster University at Hamilton, Ontario, Eaton announced that he would put forward a considerable sum of his own money if the papers went to McMaster. Some deft work by the librarian there secured the rest of the required capital, and the papers were purchased in 1968. Thus was created the ‘Bertrand Russell Archives’, as Russell insisted it be called, rejecting the original appellation of ‘Archive’; it is a major resource for British history of Russell’s time, and for the many other concerns in which he was involved. Soon after its launch in 1972, the first Russell conference at McMaster took place, to commemorate the centenary of his birth; its proceedings were published as a book four years later.

scholarly journals The Mysterious 14C Decline

Radiocarbon ◽  
2009 ◽  
Vol 51 (1) ◽  
pp. 109-119 ◽  
Author(s):  
Wallace Broecker
Keyword(s):  
Age Differences ◽  
Radiocarbon Dating ◽  
Progressive Increase ◽  
Time Interval ◽  
Last Deglaciation ◽  
Polar Ice ◽  
Radiocarbon Age ◽  
Surface Ocean ◽  
The Past ◽  
The Last Deglaciation

Fundamental to the field of radiocarbon dating is not only the establishment of the temporal record of the calendar age-radiocarbon age offsets but also the development of an understanding of their cause. Although part of the decline in the magnitude of this offset over the past 40,000 can be explained by a drop in 14C production rate associated with a progressive increase in the strength of the Earth's magnetic shielding, it is clear that changes in the distribution of 14C among the Earth's active carbon reservoirs are also required. In particular, the steep 15% decline in the 14C to C ratio in atmospheric CO2 and surface ocean ΣCO2, which occurred in a 3 kyr-duration interval marking the onset of the last deglaciation, appears to require that a very large amount (at least 5000 gigatons) of 14C-deficient carbon was transferred to or within the ocean during this time interval. As no chemical or stable isotope anomaly associated with this injection appears in either the marine sediment or polar ice records, this injection must involve a transfer within the ocean (i.e. a mixing of 2 ocean reservoirs, one depleted in 14C and the other enriched in 14C). Although evidence for the existence of a salt-stabilized glacial-age abyssal ocean reservoir exists, a search based on benthic-planktic age differences and 13C measurements appears to place a limit on its size well below that required to account for the steep 14C decline.

The Potential of Fossil Mammal Middens as Indicators of Vegetation History in Central Australia

1991 ◽  
Vol 39 (3) ◽  
pp. 305 ◽  
Author(s):  
SL Berry
Keyword(s):  
Vegetation History ◽  
Plant Macrofossil ◽  
Radiocarbon Age ◽  
North East ◽  
Vegetation Zones ◽  
History Of ◽  
Vertical Slice ◽  
Components Analysis ◽  
Central Australia ◽  
Weak Tendency

The plant macrofossil contents of two fossil mammal middens were investigated. Midden MS was collected from near Mt Swan, 200 km north-east of Alice Springs in central Australia. The vegetation in this region is predominantly grassland scattered with low trees. Midden KS was collected from Kathleen Springs, 240 km west-south-west of Alice Springs. The flora in this locality is dominated by forbs and chenopods. Midden KS had a radiocarbon age of 1700 years BP at the top and 3500 years BP at the bottom. Most of the plant taxa in each midden were components in the flora of the vegetation zones currently surrounding that midden. However, the two middens, collected from different vegetation zones, shared only 33% of taxa. Similarly, only 24% of species were common to the July 1987 vegetation at the two localities. A vertical slice of midden KS was cut into 25 subsamples. No progressive change of subsample plant macrofossil assemblage with depth could be detected by Principal Components Analysis. However, there was a weak tendency for subsamples from the same level in the midden to be similar. It was concluded that mammal middens are potentially useful indicators of the vegetation history of central Australia.

No significant ice-sheet expansion beyond present ice margins during the past 4500 yr at Rauer Group, East Antarctica

2010 ◽  
Vol 74 (1) ◽  
pp. 23-25 ◽  
Author(s):  
Sonja Berg ◽  
Bernd Wagner ◽  
Duanne A. White ◽  
Martin Melles
Keyword(s):  
Sediment Core ◽  
Radiocarbon Dating ◽  
Ice Sheet ◽  
East Antarctica ◽  
Antarctic Ice Sheet ◽  
The Holocene ◽  
The Core ◽  
The Past ◽  
Field Evidence ◽  
History Of

AbstractThe history of glacial advances and retreats of the East Antarctic ice sheet during the Holocene is not well-known, due to limited field evidence in both the marine and terrestrial realm. A 257-cm-long sediment core was recovered from a marine inlet in the Rauer Group, East Antarctica, 1.8 km in front of the present ice-sheet margin. Radiocarbon dating and lithological characteristics reveal that the core comprises a complete marine record since 4500 yr. A significant ice-sheet expansion beyond present ice margins therefore did not occur during this period.

Peat isotopic composition of a deep deposit of palsa mire for the reconstruction of environmental changes in permafrost domain of Northern Siberia

2021 ◽  
Author(s):  
Prokushkin Anatoly ◽  
Novenko Elena ◽  
Kupryanov Dmitry ◽  
Serikov Sergey
Keyword(s):  
Isotopic Composition ◽  
Radiocarbon Dating ◽  
Environmental Changes ◽  
Vegetation Changes ◽  
Northern Siberia ◽  
Plant Macrofossil ◽  
Peat Core ◽  
The Past ◽  
Diagenetic Alteration ◽  
C And N

<p>Palsa peatlands are a significant carbon pool in Northern hemisphere which is subjected to change due to accelerated permafrost thaw and peat decomposition with progressing global warming. On the other hand, peat deposits of palsas serve as an important conduit of information about variability of environment conditions in the past millennia and respective vegetation changes. In our study we applied the multi-proxy record to distinguish variation in hydrothermal regimes of palsa peatland in Northern Siberia and to trace the likely diagenetic alteration of accumulated peat.</p><p>The study site is located 10 km North-East of Igarka settlement (67<sup>o</sup>31’ N, 86<sup>o</sup>38’E) within the area underlain discontinuous permafrost. The peat core was obtained in the central intact part of elevated (ca. > 3.5 m above surrounding hollows) dry hummock. The active layer, thawed seasonally layer, at the coring site was about 0.6 m. The entire depth of peat deposit was 8.6 m, but interrupted with several relatively thin (0.1-0.2 m) ice-rich lenses. Thawed and frozen peat samples of 0.5-5.0 cm thickness (mean = 2.8 cm) were collected at 2.5-12.0 cm step (mean =5.4 cm) depending on the amount of peat material. Collected samples (n = 160) after drying at 60<sup>o</sup>C for 48 h were subjected to the analysis for C and N content, stable isotopic composition of C and N. These measurements will further accompany radiocarbon dating, loss on ignition, plant macrofossil and macro charcoal analyses.</p><p>The analyzed 8.6 m deep peat core demonstrated the large variation of C (17.3-54.7%) and N (0.37-3.26 %) contents as well as C:N ratios (14-134). The isotopic depth profile was in the range from -24.51 to -34.31 ‰ for d<sup>13</sup>C and from -1.77 to 6.96 ‰ for d<sup>15</sup>N. The highest enrichment in <sup>15</sup>N (2.69±1.60 ‰ d<sup>15</sup>N) was found in seasonally thawed layer (≤0.6 m). A layer close to the bottom (6.9-8.3 m) contained peat the most depleted by <sup>13</sup>C (<-30 ‰ d<sup>13</sup>C). Meanwhile, along the peat profile depth we detected significant fluctuations in these parameters suggesting the different periods with specific environmental conditions.</p><p>Further combined with radiocarbon dating and plant macrofossil analyses we will attempt to capture the changes occurred during the past epochs in an input matter (vegetation changes and/or its productivity), decomposition rates as well as hydrothermal regimes and permafrost processes like aggradation (e.g. hummock uplift and cryoturbation) and degradation (e.g. hummock collapse, shifts from minerotrophic to ombrotrohic conditions and vice versa).</p><p>This work was supported by the Russian Science Foundation, project № 20-17-00043.</p>

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