BRYOPHYTE SUBFOSSILS OF A LATE-GLACIAL DEPOSIT FROM THE MISSOURI COTEAU, SASKATCHEWAN

1965 ◽  
Vol 43 (8) ◽  
pp. 947-953 ◽  
Author(s):  
B. de Vries ◽  
C. D. Bird
Keyword(s):  
Boreal Forest ◽  
Higher Plants ◽  
Late Glacial ◽  
Organic Layer ◽  
Middle Zone ◽  
Higher Plant ◽  
Glacial Deposit ◽  
Boreal Species ◽  
The North ◽  
Missouri Coteau

Bryophyte and associated macro-subfossils were recovered from a kettle located in prairie southwest of Moose Jaw in the Missouri Coteau of southern Saskatchewan. The higher plants were discussed in an earlier paper.Three samples taken from the organic layer gave C14 datings ranging from 11,650 ± 150 to 10,270 ± 150 B.P.Sixteen species and one variety of Musci were recovered. Eleven of these were found in the lowermost zone at a depth of 510–450 cm. This zone was composed of bryophytes and higher plants characteristic of a modern Picea forest. Fifteen bryophyte taxa were recovered from the middle zone at a depth of 450–290 cm. The macro-subfossils in this zone are typical of a present-day Populus–Picea forest. No bryophytes were found in the upper layer, 290–280 cm characterized by higher plant macro-subfossils and pollen typical of a modern Picea forest.All bryophytes recovered belong to present-day taxa; however, many of the boreal species are not now found in the region as the southern margin of the boreal forest is now 200 miles to the north.

CONTRIBUTIONS TO THE HOLOCENE PALEOECOLOGY OF WESTCENTRAL CANADA: A LATE-GLACIAL DEPOSIT FROM THE MISSOURI COTEAU

1964 ◽  
Vol 42 (6) ◽  
pp. 677-692 ◽  
Author(s):  
J. C. Ritchie ◽  
Bernard de Vries
Keyword(s):  
Great Plains ◽  
Late Glacial ◽  
Pollen Spectrum ◽  
Pollen Diagram ◽  
Glacial Deposit ◽  
Carbon 14 ◽  
Missouri Coteau ◽  
Plant Assemblages ◽  
Mixed Prairie ◽  
Artemisia Pollen

A buried deposit of limnic sediment was excavated from a site on the Missouri Coteau of Saskatchewan, within the Mixed Prairie section of the Great Plains. Carbon-14 determinations indicate that the section is late-glacial, possibly deposited during an interstadial terminated by the Condie (= Valders?) re-advance. On the basis of the records of about 60 taxa of Tracheophyta and a pollen diagram, the section is characterized by lower, middle, and upper plant assemblages. It is suggested that the lower and upper assemblages, distinguished mainly by a Picea – Shepherdia canadensis – Salix – Artemisia pollen spectrum, indicate the prevalence on mesic sites of a spruce forest. The middle assemblage, having an array of macrofossils and a few microfossils of temperate geographical affinity and a pollen spectrum suggesting relatively less spruce and (or) more herbaceous vegetation, is interpreted in terms of a mixed spruce–poplar forest on mesic sites with shrub and grassland communities on the more xeric habitats. This tripartite division of the section in terms of ecologically concordant plant assemblages suggests an amelioration of environment followed by a deterioration which was probably correlative with the Condie re-advance.

The reduction of organic-layer depth by wildfire in the North American boreal forest and its effect on tree recruitment by seed

2007 ◽  
Vol 37 (6) ◽  
pp. 1012-1023 ◽  
Author(s):  
David F. Greene ◽  
S. Ellen Macdonald ◽  
Sybille Haeussler ◽  
Susy Domenicano ◽  
Josée Noël ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Inverse Function ◽  
Organic Layer ◽  
Layer Depth ◽  
Tree Recruitment ◽  
Organic Layers ◽  
Boreal Region ◽  
The North ◽  
Forest Species Composition

We compared prefire and postfire organic-layer depths in boreal forest types (14 fires) across Canada, and examined tree recruitment as a function of depth. There was extensive within-stand variation in depth, much of it due to clustering of thinner organic layers around boles. There were no significant differences in postfire organic-layer depth among sites with different prefire forest species composition, but sites in the eastern boreal region had thicker postfire organic layers than those in the western boreal region. Mean organic-layer depth was much greater in intact stands than after fires; overall, fire reduced organic-layer depth by 60%, largely because of increases in the area of thin (<3 cm) organic layers (1% in intact stands vs. 40% in postfire stands). There was more variation in organic-layer depth within postfire than within prefire stands; notably, some areas in postfire stands were deeply combusted, while adjacent parts were only lightly combusted. We speculate that the diminished role of energy loss to latent heat around tree boles increased organic-layer consumption around tree boles. Seedlings were clustered around burned tree bases, where organic layers were thinner, and the dependence of a species on thin organic layers was an inverse function of seed size.

Late-glacial (Allerød – Younger Dryas) Coleoptera from central Cape Breton Island, Nova Scotia, Canada

1997 ◽  
Vol 34 (3) ◽  
pp. 247-259 ◽  
Author(s):  
Randall F. Miller
Keyword(s):  
Nova Scotia ◽  
Boreal Forest ◽  
Younger Dryas ◽  
Ground Cover ◽  
Late Glacial ◽  
Polar Front ◽  
Climate Data ◽  
Cape Breton Island ◽  
The North ◽  
Cape Breton

Coleoptera from three late-glacial sites on Cape Breton Island, Nova Scotia, Canada, provide proxy climate data from 12 600 to 10 400 BP. Samples older than about 11 800 BP contain tundra to tree-line species. Between 11 800 and about 10 800 BP, beetle assemblages become typical of the modern boreal forest. Beetles younger than 10 800 BP responded to climatic deterioration during the Younger Dryas. Although coleopteran evidence for the Younger Dryas is not as strong as that presented by palynological and stratigraphic studies, the appearance of Olophrum boreale and other species found today in the northern boreal forest and on tundra or coastal tundra corresponds with the decline of shrub birch and the rise in willow and alder pollen. Beetles responded just as likely to changes in vegetation and ground cover as to changes in temperature. The extent to which Coleoptera were affected may lie somewhere between a moderated continental response seen in the Great Lakes region in North America and more extreme changes recorded in Europe. This response is consistent with shifts in the North Atlantic oceanic Polar Front in the Ruddiman and McIntyre model.

A palynological investigation of true-moss (Bryidae) spores: morphology and occurrence in modern and late Quaternary lake sediments of Alaska

1998 ◽  
Vol 76 (12) ◽  
pp. 2145-2157 ◽  
Author(s):  
L B Brubaker ◽  
P M Anderson ◽  
B M Murray ◽  
D Koon
Keyword(s):  
Boreal Forest ◽  
Late Quaternary ◽  
Late Glacial ◽  
North Slope ◽  
Wall Structure ◽  
Herbarium Specimens ◽  
Glacial Sediments ◽  
The North ◽  
True Moss ◽  
Southwestern Alaska

This study describes (i) spore morphology of 121 Alaskan species of true moss (Bryidae) and (ii) percentages of Bryidae and Sphagnum spores in mud-water interface samples from 46 Alaskan lakes and a late-Quaternary sediment core from Idavain Lake in southwestern Alaska. Bryidae spores were collected from herbarium specimens, prepared by standard palynological chemical treatment and described under light microscopy. An identification key based on spore shape, wall structure, and size recognized 11 major morphological groups. Although family, genus, or species identifications were not possible for most groups, spores of a few genera and species were distinctive. Bryidae spores occurred in 80% of the modern sediment samples, representing boreal forest and three areas of tundra (North Slope, Seward Peninsula, and southwestern Alaska). Bryidae and Sphagnum spore percentages showed greatest differences between the North Slope tundra and other vegetation types, whereas pollen percentages distinguished boreal forest from tundra regions as a group. Bryidae spores were present throughout the Idavain Lake record but were most common in late-glacial sediments. Variations in the abundance of Bryidae spores are consistent with or enhance paleoenvironmental interpretations based on pollen and other spore types.Key words: Bryidae, palynology, spores, Alaska, Quaternary, paleoenvironment.

Carex ×payettei, a new hybrid of Carex sect. Racemosae described from subarctic Quebec, Canada (Cyperaceae)

Phytotaxa ◽  
2021 ◽  
Vol 483 (2) ◽  
pp. 139-148
Author(s):  
JACQUES CAYOUETTE ◽  
ÉTIENNE LÉVEILLÉ-BOURRET
Keyword(s):  
Boreal Forest ◽  
North American ◽  
Parental Species ◽  
Pollen Stainability ◽  
Boreal Species ◽  
Forest Tundra ◽  
The North

A new hybrid is described between two boreal species of Carex sect. Racemosae, the North American Carex atratiformis and the circumboreal Carex media, under the name of Carex ×payettei. It is reported in Nunavik (Northern Quebec, Canada), in nine localities within the Forest Tundra and Open Boreal Forest zones. It is intermediate in morphology between the parental species and is not completely sterile, frequently producing fruits. Pollen stainability of the hybrid varied between 10% and 37% while its parents display values above 95%.

scholarly journals Late Glacial and Holocene plant cover in Węgliny, Lubsza Plain, south-west Poland, based on pollen analysis

2013 ◽  
Vol 53 (2) ◽  
pp. 191-233 ◽  
Author(s):  
Aleksandra Jurochnik ◽  
Dorota Nalepka
Keyword(s):  
Pollen Analysis ◽  
Plant Cover ◽  
Late Glacial ◽  
Anaerobic Sediments ◽  
The North ◽  
South West ◽  
Pollen Diagrams ◽  
Laacher See Tephra ◽  
Late Glacial And Holocene

ABSTRACT Late Glacial (since Oldest Dryas) and Holocene (to Subatlantic) changes of vegetation at the Węgliny site (south-west Poland) are reconstructed based mainly on pollen analysis of five cores from the palaeobasin (anaerobic sediments). The chronology of the described events is based on palynological comparison with the Lubsza Plain environs, based on LPAZs from several published pollen diagrams on 14C data, and multiple cryptotephra levels determined in the Węgliny profiles. The Węgliny record integrates well into the north European Holocene and Late Glacial biostratigraphic framework. The Węgliny site is the next (fourth) locality in Poland where the Laacher See Tephra (LST) horizon within the Allerød chronozone was identified.

Measurement of ferrochelatase activity using a novel assay suggests that plastids are the major site of haem biosynthesis in both photosynthetic and non-photosynthetic cells of pea (Pisum sativum L.)

2002 ◽  
Vol 362 (2) ◽  
pp. 423-432 ◽  
Author(s):  
Johanna E. CORNAH ◽  
Jennifer M. ROPER ◽  
Davinder Pal SINGH ◽  
Alison G. SMITH
Keyword(s):  
Ferrous Iron ◽  
Specific Activity ◽  
Higher Plants ◽  
Protoporphyrin Ix ◽  
Chlorophyll Synthesis ◽  
Marker Enzyme ◽  
Hexane Extraction ◽  
Higher Plant ◽  
Major Site ◽  
Haem Biosynthesis

Ferrochelatase is the terminal enzyme of haem biosynthesis, catalysing the insertion of ferrous iron into the macrocycle of protoporphyrin IX, the last common intermediate of haem and chlorophyll synthesis. Its activity has been reported in both plastids and mitochondria of higher plants, but the relative amounts of the enzyme in the two organelles are unknown. Ferrochelatase is difficult to assay since ferrous iron requires strict anaerobic conditions to prevent oxidation, and in photosynthetic tissues chlorophyll interferes with the quantification of the product. Accordingly, we developed a sensitive fluorimetric assay for ferrochelatase that employs Co2+ and deuteroporphyrin in place of the natural substrates, and measures the decrease in deuteroporphyrin fluorescence. A hexane-extraction step to remove chlorophyll is included for green tissue. The assay is linear over a range of chloroplast protein concentrations, with an average specific activity of 0.68nmol·min−1·mg of protein−1, the highest yet reported. The corresponding value for mitochondria is 0.19nmol·min−1·mg of protein−1. The enzyme is inhibited by N-methylprotoporphyrin, with an estimated IC50 value of ≈ 1nM. Using this assay we have quantified ferrochelatase activity in plastids and mitochondria from green pea leaves, etiolated pea leaves and pea roots to determine the relative amounts in the two organelles. We found that, in all three tissues, greater than 90% of the activity was associated with plastids, but ferrochelatase was reproducibly detected in mitochondria, at levels greater than the contaminating plastid marker enzyme, and was latent. Our results indicate that plastids are the major site of haem biosynthesis in higher plant cells, but that mitochondria also have the capacity for haem production.

scholarly journals Effects of lightning and other meteorological factors on fire activity in the North American boreal forest: implications for fire weather forecasting

2010 ◽  
Vol 10 (14) ◽  
pp. 6873-6888 ◽  
Author(s):  
D. Peterson ◽  
J. Wang ◽  
C. Ichoku ◽  
L. A. Remer
Keyword(s):  
Boreal Forest ◽  
North American ◽  
Meteorological Factors ◽  
Convective Available Potential Energy ◽  
Fire Weather ◽  
Lightning Strikes ◽  
The North ◽  
Lightning Detection ◽  
Western Boreal Forest ◽  
Consecutive Dry Days

Abstract. The effects of lightning and other meteorological factors on wildfire activity in the North American boreal forest are statistically analyzed during the fire seasons of 2000–2006 through an integration of the following data sets: the MODerate Resolution Imaging Spectroradiometer (MODIS) level 2 fire products, the 3-hourly 32-km gridded meteorological data from North American Regional Reanalysis (NARR), and the lightning data collected by the Canadian Lightning Detection Network (CLDN) and the Alaska Lightning Detection Network (ALDN). Positive anomalies of the 500 hPa geopotential height field, convective available potential energy (CAPE), number of cloud-to-ground lightning strikes, and the number of consecutive dry days are found to be statistically important to the seasonal variation of MODIS fire counts in a large portion of Canada and the entirety of Alaska. Analysis of fire occurrence patterns in the eastern and western boreal forest regions shows that dry (in the absence of precipitation) lightning strikes account for only 20% of the total lightning strikes, but are associated with (and likely cause) 40% of the MODIS observed fire counts in these regions. The chance for ignition increases when a threshold of at least 10 dry strikes per NARR grid box and at least 10 consecutive dry days is reached. Due to the orientation of the large-scale pattern, complex differences in fire and lightning occurrence and variability were also found between the eastern and western sub-regions. Locations with a high percentage of dry strikes commonly experience an increased number of fire counts, but the mean number of fire counts per dry strike is more than 50% higher in western boreal forest sub-region, suggesting a geographic and possible topographic influence. While wet lightning events are found to occur with a large range of CAPE values, a high probability for dry lightning occurs only when 500 hPa geopotential heights are above ~5700 m and CAPE values are near the maximum observed level, underscoring the importance of low-level instability to boreal fire weather forecasts.

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