Climate and Vegetation of the Interior Lowlands of Southern Baffin Island : Long-term Stability at the Low Arctic Limit

The interior of southern Baffin Island between 64 N and 68 N latitude is a mainly lowland area over 50 000 km² in extent, containing two large lakes (Amadjuak and Nettilling) and numerous smaller lakes and ponds. This area is important as summer range for caribou and a variety of birds, and there is evidence for a human presence as early as 3000 B.P. Field studies between 1984 and 1988 and the operation of climatic autostations from 1987 to 1995 revealed a warm summer climate and cold winters. There is a locally rich and diverse vegetation, including Betula glandulosa and other species that are indicative of the low arctic bioclimatic zone and mark the present northern limit of that zone in the eastern Canadian Arctic. Air photos and Landsat imagery were used to map vegetation beyond the field areas, leading to an estimate of 46% of the land area in continuous vegetation (tundra) of some type and 15% with shrub and heath elements. Palynology of sediment cores taken from Nettilling Lake permitted extrapolation from present bioclimatic conditions to 4750 years B.P. Betula and therefore elements of a low arctic vegetation association appear to have been present in the area during most of that period, indicating a local bioclimatic system that has been relatively stable under regional variations of climate.La région intérieure du sud de la terre de Baffin située entre le 64° et le 68° de latit. N. est essentiellement une zone de basses-terres s'étendant sur plus de 50 000 km², qui renferme deux grands lacs (Amadjuak et Nettilling) et de nombreux petits lacs et étangs. Cette région est importante en tant que territoire estival du caribou et d'une diversité d'oiseaux, et on y a découvert des preuves attestant une présence humaine dès 3000 BP. Des études sur le terrain menées entre 1984 et 1988 et l'activité de stations climatologiques automatisées de 1987 à 1995 ont révélé un climat d'été tempéré et d'hiver froid. La végétation locale est riche et diversifiée et comprend Betula glandulosa ainsi que d'autres espèces typiques d'une zone bioclimatique du Bas-Arctique et marquant la limite septentrionale actuelle de cette zone dans l'Arctique canadien oriental. Des clichés aériens et des images du satellite Landsat ont servi à cartographier la végétation au-delà des zones d'étude sur le terrain, ce qui a amené à une estimation de 46 p. cent de la zone possédant un couvert végétal continu (toundra) d'une certaine sorte et 15 p. cent possédant des composants d'arbrisseaux et de bruyère. La palynologie de carottes de sédiments provenant du lac Nettilling a permis d'extrapoler les conditions bioclimatiques depuis la période actuelle jusqu'à 4750 ans BP. Il semble que Betula et par conséquent des composants d'une association végétale du Bas-Arctique ont été présents dans la région pendant la plus grande partie de cette période, ce qui révèle l'existence d'un système bioclimatique relativement stable à l'intérieur de variations climatiques régionales

Report on the Distribution of Dwarf Birches and Present Pollen Rain, Baffin Island, N.W.T., Canada

A distribution map for the dwarf birches is presented for the region from Frobisher Bay northward to Cumberland Peninsula. These shrubs are restricted to favourable habitats which, at the northern limit of the species (67 deg. 40 sec. N), are found on south-facing slopes above the immediate local cooling influence of the sea. Pollen studies within the zone of scattered dwarf birch indicate that pollen dispersal from these low, prostrate shrubs is minimal. Samples of moss collected beneath the bushes have 5-36% Betula pollen; whereas sites no more than 50 m away from Betula shrubs have percentages of <2%. These data will be useful in considering the Holocene and Pleistocene histories of these Low Arctic shrubs in the Eastern Canadian Arctic

Climate and Vegetation of the Interior Lowlands of Southern Baffin Island: Long-term Stability at the Low Arctic Limit

The interior of southern Baffin Island between 64 N and 68 N latitude is a mainly lowland area over 50 000 km² in extent, containing two large lakes (Amadjuak and Nettilling) and numerous smaller lakes and ponds. This area is important as summer range for caribou and a variety of birds, and there is evidence for a human presence as early as 3000 B.P. Field studies between 1984 and 1988 and the operation of climatic autostations from 1987 to 1995 revealed a warm summer climate and cold winters. There is a locally rich and diverse vegetation, including Betula glandulosa and other species that are indicative of the low arctic bioclimatic zone and mark the present northern limit of that zone in the eastern Canadian Arctic. Air photos and Landsat imagery were used to map vegetation beyond the field areas, leading to an estimate of 46% of the land area in continuous vegetation (tundra) of some type and 15% with shrub and heath elements. Palynology of sediment cores taken from Nettilling Lake permitted extrapolation from present bioclimatic conditions to 4750 years B.P. Betula and therefore elements of a low arctic vegetation association appear to have been present in the area during most of that period, indicating a local bioclimatic system that has been relatively stable under regional variations of climate

A 1400-Year Bølling-Allerød Tree-Ring Record from the U.S. Great Lakes Region

Since the late 19th Century, geologists and naturalists working in the US Midwest have reported an abundance of tree macrofossils embedded in glacial and lacustrine deposits formed after the Last Glacial Maximum. The most widely-known of these sites is the Two Creeks type locality in Wisconsin. We report progress on development of a long tree-ring record from this subfossil wood in the US Great Lakes region, employing samples collected during a decade-long series of field campaigns at recently eroded lake shorelines, construction projects, and excavations, along with acquisition of archived samples collected from the 1950s to the 1980s during past lake erosion events. A previously-reported tree-ring chronology from the Two Creeks type locality reached ca. 250 years in length; here we used radiocarbon dates and tree-ring crossdating to develop a 1408-year tree-ring chronology (mainly spruce Picea spp. with some tamarack Larix) comprising a total of 135 overlapped tree-ring width series in three clusters from nine locations in eastern Wisconsin. The calendar age of the record is estimated with 46 14C dates to between 14,500 to 13,100 cal BP. This is currently the oldest and only long tree-ring record in North America from the boreal environments of the Bølling-Allerød warm period during the transition from the Late Glacial to the Holocene. © 2017 by The Tree-Ring Society.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]