Standing crop and net production of sedge meadows of an ungrazed polar desert oasis

1990 ◽  
Vol 68 (12) ◽  
pp. 2660-2667 ◽  
Author(s):  
G. H. R. Henry ◽  
J. Svoboda ◽  
B. Freedman
Keyword(s):  
Standing Crop ◽  
Growth Period ◽  
High Arctic ◽  
Climatic Conditions ◽  
Large Herbivores ◽  
Net Production ◽  
Carex Aquatilis ◽  
Eriophorum Angustifolium ◽  
Desert Oasis ◽  
Sedge Meadows

Standing crop and net production were measured in sedge meadow communities of a coastal lowland at Alexandra Fiord, Ellesmere Island (79°N), a high arctic oasis. The meadows are dominated by Carex aquatilis stans, Carex membranacea, and Eriophorum angustifolium triste. Dwarf shrubs (Dryas integrifolia and Salix arctica) are also important constituents. Total standing crop ranged from 1400 to 3200 g/m2 and was largely (50–80%) composed of attached dead matter. The accumulation of litter and dead roots and rhizomes is attributed to low rates of decomposition, and to a lack of grazing by large herbivores such as muskox. Net production (100–200 g/m2) was similar to more southerly tundra meadows, emphasizing the oasis-like nature of this high arctic location. Furthermore, net production did not vary significantly among sites or years. The consistent net production was due to similar edaphic and climatic conditions, the concentration of biomass belowground, and the apparently fixed growth period of arctic sedges. Key words: sedge meadows, high arctic, net production, standing crop, Carex.

ZOOPLANKTON OF LAKE HAZEN, ELLESMERE ISLAND, AND A NEARBY POND, WITH SPECIAL REFERENCE TO THE COPEPOD CYCLOPS SCUTIFER SARS

1964 ◽  
Vol 42 (4) ◽  
pp. 613-629 ◽  
Author(s):  
I. A. McLaren
Keyword(s):  
Special Reference ◽  
Standing Crop ◽  
Dry Weight ◽  
High Arctic ◽  
Ellesmere Island ◽  
Arctic Lakes ◽  
Net Production ◽  
Daphnia Middendorffiana ◽  
Ice Conditions ◽  
Cyclops Scutifer

Zooplankton was studied in the large, high-arctic Lake Hazen and in a small nearby pond. Primary (O2) production in Lake Hazen may have occurred largely before the ice began to melt, but was unmeasurable in summer. Primary production in the pond was about the same as in other small arctic lakes, Cyclops scutifer was overwhelmingly dominant in Lake Hazen. C. scutifer and Daphnia middendorffiana were commonest in the pond. C, scutifer is annual in Scandinavia, often with coexisting spring-born and fall-born generations. On Ellesmere Island the pond appears to contain alternating annual and biennial generations, whereas the species is strictly biennial in Lake Hazen. Numbers of C. scutifer in Lake Hazen were greatly reduced as a result of summer ice conditions between 1958 and 1961, while the rotifer Keratella hiemalis increased. Estimated mean standing crop (96 mg/m2) and net production (1.0 mg/m2 day) in dry weight ol C. scutifer in Lake Hazen during the summer of 1958 were extremely low. In early August the crop of this species in the pond was abont the same as in Lake Hazen, but net production was sonic 15 times as large, and other zooplankters added considerably to crop and production of the pond.

Effects of fertilization on three tundra plant communities of a polar desert oasis

1986 ◽  
Vol 64 (11) ◽  
pp. 2502-2507 ◽  
Author(s):  
G. H. R. Henry ◽  
B. Freedman ◽  
J. Svoboda
Keyword(s):  
Plant Communities ◽  
High Arctic ◽  
Ellesmere Island ◽  
Nutrient Addition ◽  
The Arctic ◽  
Arctic Ecosystems ◽  
Polar Desert ◽  
Net Production ◽  
Dwarf Shrubs ◽  
Desert Oasis

Three plant communities studied at a high arctic oasis on Ellesmere Island responded to nutrient addition. Response to nitrogen was greatest in the driest community and weaker in the more mesic and wet-mesic communities. Nutrient addition resulted in (i) increased inflorescence densities of dicotyledonous and certain graminoid species; (ii) increased tiller densities of wet sedge species; and (iii) increased net production of graminoids and forbs at high rates of application, and in some dwarf shrubs at lower rates. These results parallel those of studies at lower latitudes in the Arctic, and support the hypothesis that arctic ecosystems are typically oligotrophic.

Radiocarbon Age of Soils in Oases of East Antarctica

Radiocarbon ◽  
2016 ◽  
Vol 59 (2) ◽  
pp. 489-503 ◽  
Author(s):  
E Zazovskaya ◽  
N Mergelov ◽  
V Shishkov ◽  
A Dolgikh ◽  
V Miamin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Vascular Plants ◽  
High Arctic ◽  
Climatic Conditions ◽  
East Antarctica ◽  
Radiocarbon Age ◽  
Antarctic Soils ◽  
Larsemann Hills ◽  
Arctic Soils ◽  
Organic Horizons

AbstractThis article discusses radiocarbon dating results for soils and soil-like systems in the East Antarctic oases, including Schirmacher, Thala Hills, and Larsemann Hills. The organic matter of endolithic and hypolithic systems, soils of wind shelters, and soils under moss-algae vegetation were dated along with micro- and macroprofiles. Organic matter pools formed under extreme climatic conditions and originated not from vascular plants but from cryptogamic organisms, and photoautotrophic microbes have been identified within the oases of the East Antarctica. The organic matter of the most of East Antarctic soils is young and cannot reach a steady state because of the high dynamism in the soil cover due to active erosion. The oldest soil organic matter in East Antarctica was found in the soils formed in wind shelters and endolithic soil-like systems under the protection of consolidated rock surfaces. According to our data, the maximal duration for the formation of organic matter profiles within the oases of East Antarctica is ~500 yr, which is similar to the age determined for High Arctic soils in Eurasia. The absence of older soils, comparable with the Holocene deglaciation, can be due to the extreme conditions resulting in occasional catastrophic events that destroyed the soil organic horizons.

Energy Flow and Secondary Production of the Amphipods Hyalella azteca and Crangonyx richmondensis occidentalis in Marion Lake, British Columbia

1971 ◽  
Vol 28 (5) ◽  
pp. 711-726 ◽  
Author(s):  
Jack A. Mathias
Keyword(s):  
Population Growth ◽  
Energy Flow ◽  
Standing Crop ◽  
Production Efficiency ◽  
Hyalella Azteca ◽  
Growth Efficiency ◽  
Ecological Efficiency ◽  
Net Production ◽  
Annual Basis ◽  
Predator System

The Hyalella azteca population in Marion Lake, B.C., assimilated and produced about three times as much energy as did the Crangonyx richmondensis occidentalis population from May 1966 to May 1967, but during the summer the energy flow of H. azteca was four times, and production was five times, that of C. r. occidentalis.Hyalella azteca was abundant at a depth of 1.0 m (mean summer standing crop, 1952 animals/m2), but was rare (75 animals/m2) at depths greater than 2.5 m. Growth, molting, respiration, and hence energy flow rates decreased with depth, due (in part) to lower ambient temperatures in deeper water. On an annual basis, a mean standing crop of 1.1 kcal/m2 of H. azteca assimilated 18.1 kcal/m2, respired 13.5 kcal/m2, and used 4.6 kcal/m2 in production of growth, molts, and eggs. Approximately two-thirds of the annual energy flow was completed between June and October. On an annual basis, the ecological efficiency of an H. azteca-predator system was in the range 2.5–12.5%, the net production efficiency was 25%, and the net population growth efficiency was 16%.The mean summer density of C. r. occidentalis remained constant with depth (about 283 animals/m2). Annual energy flow and production were not appreciably affected by lower temperatures in deeper water. On an annual basis, a mean standing crop of 0.7 kcal/m2 assimilated 6.5 kcal/m2, respired 5.2 kcal/m2, and used 1.4 kcal/m2 in production. Crangonyx r. occidentalis energy flow was fairly constant throughout the year. The ecological efficiency of a C. r. occidentalis-predator system was in the range 2–10.5%, the net production efficiency was 21%, and the population growth efficiency was 17% on an annual basis.

scholarly journals Survival of Young Greater Snow Geese (Chen Caerulescens Atlantica) During Fall Migration

The Auk ◽  
2005 ◽  
Vol 122 (2) ◽  
pp. 479-496 ◽  
Author(s):  
Stéphane Menu ◽  
Gilles Gauthier ◽  
Austin Reed
Keyword(s):  
Body Mass ◽  
High Arctic ◽  
Climatic Conditions ◽  
Factors Affecting ◽  
Chen Caerulescens ◽  
Migratory Flight ◽  
Snow Geese ◽  
Before And After ◽  
Chen Caerulescens Atlantica ◽  
Similar Survival

Abstract The many hazards that await birds along their migratory routes may negatively affect their survival, especially among newly fledged young. We estimated survival of young Greater Snow Geese (Chen caerulescens atlantica) during fall migration from the High Arctic to temperate areas and examined factors affecting their survival over a five-year period, using two approaches. First, each year (1993–1997), we banded fledglings and adults in mid-August, just before their departure from Bylot Island in the High Arctic (Nunavut, Canada), and again at an important staging area 3,000 km to the south at the Cap Tourmente National Wildlife Area (Québec, Canada) in October; recovery data from those two banding periods allowed estimation of survival during fall migration. Second, we visually determined brood size of neck-banded females before and after the main portion of the migratory flight, to estimate survival of young. The two approaches yielded similar survival estimates and showed the same interannual variation, thus suggesting that estimates were reliable. Mortality of young shortly after fledging and during the fall migration was high, compared with that of adults (monthly survival 0.662 in young vs. 0.989 in adults). However, mortality of young after migration was similar to that of adults (monthly survival 0.969 in young vs. 0.972 in adults). Migration survival of young varied considerably among annual cohorts (range of 0.119–0.707 over five years), and most of the mortality appeared to be natural. Survival was especially low in years when (1) temperatures at time of fledging and start of migration were low (i.e. near or below freezing), (2) mean body mass of goslings near fledging was low, or (3) mean fledging date was late. Our results suggest that migration survival of young is affected by a combination of several factors (climatic conditions, body mass, and fledging date) and that survival is reduced when one of those factors intervenes.

scholarly journals Mass Balance of Two High Arctic Plateau Ice Caps

1987 ◽  
Vol 33 (113) ◽  
pp. 123-128 ◽  
Author(s):  
Raymond S. Bradley ◽  
Mark C. Serreze
Keyword(s):  
Mass Balance ◽  
High Arctic ◽  
Climatic Conditions ◽  
Ellesmere Island ◽  
Equilibrium Line ◽  
Ice Caps ◽  
Mass Losses ◽  
North Eastern ◽  
Contemporary Climate ◽  
Significant Mass

AbstractMass-balance measurements have been renewed on two small ice caps on north-eastern Ellesmere Island. Original stake networks were established in 1972 and 1976. Since then, both ice caps have experienced significant mass losses averaging –70 to –140 kg m−2a−1. They have also decreased in area. The equilibrium line in this area has averaged around 1150 m for the last decade or so. The ice caps are remnants of former climatic conditions and are out of equilibrium with contemporary climate.

Climate and ground temperature relations at sites across the continuous and discontinuous permafrost zones, northern Canada1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Earth Science Sector (ESS) Contribution 20110128.

2012 ◽  
Vol 49 (8) ◽  
pp. 865-876 ◽  
Author(s):  
Jennifer Throop ◽  
Antoni G. Lewkowicz ◽  
Sharon L. Smith
Keyword(s):  
Active Layer ◽  
High Arctic ◽  
High Elevation ◽  
Climatic Conditions ◽  
Yukon Territory ◽  
Ground Temperature ◽  
Air Temperatures ◽  
Discontinuous Permafrost ◽  
Heat Effects ◽  
Ice Content

Climate – ground temperature relations are examined under a range of conditions for 10 sites across northern Canada. The sites are located between 60°N and 83°N and at elevations of 40 to 1840 m above sea level. They encompass various environmental and climatic conditions, with permafrost temperatures that range from just below 0 to –15 °C. The substrates range from bedrock to fine-grained sediment with high ice content, and vegetation types include coniferous forests in the Mackenzie Valley, shrub tundra at high elevation in the southern Yukon Territory, and polar desert in the High Arctic. Permafrost conditions at all of these sites are determined primarily by air temperature, followed by snow and substrate conditions. The apparent thermal diffusivity is relatively high at colder sites and in bedrock and is lower at sites in sediment with high ice content. Snow has a greater influence on air–ground temperature relations at sites where mean annual air temperatures and active-layer moisture contents are relatively high, leading to physically significant latent heat effects and a slower freeze-back of the active layer.

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