Showing papers in "Arctic and alpine research in 1974"
TL;DR: Interglacial refugia may be more important than glacialRefugia in consolidating evolutionary changes in alpine taxa which evolve in response to decreasing temperatures, increasing light intensities, and in some cases to increasing drought stress.
Abstract: Alpine environments are characterized by short, cold, unpredictable growing seasons. Outside of the Arctic this growing season is characterized by cold nights as well. Alpine plant adaptations are much like those of the Arctic in morphological and physiological characteristics. However, they appear to acclimate metabolically to changes in temperature more easily than do arctic ecotypes. In fact, almost all representatives of arctic-alpine species are ecotypically different from their congeners in the Arctic. This is particularly true in reproduction and metabolism, the real heart of adaptation to cold alpine environments. While there are relatively ancient alpine plant taxa, the accelerated rise of new mountain ranges in late Pliocene and Pleistocene times has led to new floristic aggregations in alpine vegetations by migration and adaptive radiation. Fluctuations in Pleistocene glaciations have alternately allowed migrations and blocked them. Interglacial refugia may be more important than glacial refugia in consolidating evolutionary changes in alpine taxa which evolve in response to decreasing temperatures, increasing light intensities, and in some cases to increasing drought stress.
252 citations
TL;DR: Subnivean conditions, as they affect winter reproduction, influence the timing of the rise to a population peak, and thus influence the period of the cycle, it is concluded.
Abstract: Winter nests of brown and collared lemmings were examined following melt-off in 1969 through 1973 for evidence of predation by weasels during the preceding winter. In the winter of 1968-69 heavy weasel predation (34.7% of nests examined) contributed to the decline of a breeding lemming population. Weasel and bird predation in summer 1969 then drove the lemmings to a very low density. Weasel predation remained low for the duration of the study. Lemming population changes were related to the intensity of summer and, especially, winter reproduction. Reproduction was impaired in winters of unusually shallow snow cover and cold subnivean conditions. We conclude that subnivean conditions, as they affect winter reproduction, influence the timing of the rise to a population peak, and thus influence the period of the cycle. Pred
139 citations
96 citations
TL;DR: In this paper, the distribution of vegetation types and closely related to the distributions of vegetado-continuous permafrost in a representative watershed were mapped in detail, and a solar-radiation index, based on the index, although vegetation characteristics ap concept of equivalent latitude (a function of pear to be at least as important in controlling slope and aspect), was also mapped.
Abstract: The distributions of vegetation types and closely related to the distributions of vegetadiscontinuous permafrost in a representative tion and permafrost. The boundary of perma1.8-km2 drainage basin in the Yukon-Tanana frost in this area appears to coincide approxiuplands were mapped in detail. A white spruce- mately with the isopleth of 265 * cal ? cm-2 day birch forest is confined to the permafrost-free average-annual insolation. The thickness of the areas of the basin; other vegetation types are seasonally thawed zone above the permafrost is apparently underlain by permafrost at shallow significantly correlated with the solar-radiation depths. A solar-radiation index, based on the index, although vegetation characteristics apconcept of equivalent latitude (a function of pear to be at least as important in controlling slope and aspect), was also mapped, and is this.
51 citations
48 citations
TL;DR: Permafrost was discovered in 1969 at an altitude of 4,140 m near the surface of Summit Cone crater on Mauna Kea, a dormant volcano as mentioned in this paper.
Abstract: Permafrost was discovered in 1969 at an altitude of 4,140 m near the surface of Summit Cone crater on Mauna Kea, a dormant volcano
48 citations
TL;DR: In this paper, the authors reviewed the avifauna of the north slope of arctic Alaska, with particular reference to the Barrow region, using records published since Bailey (1948) and field experience in northern Alaska, mainly near Barrow, over a 23-year period (1951 to 1973).
Abstract: The avifauna of the north slope of arctic Alaska, with particular reference to the Barrow region, is reviewed on the basis of records published since Bailey (1948) and field experience in northern Alaska, mainly near Barrow, over a 23-year period (1951 to 1973). New records for the Barrow region and other parts of the north slope are reported. Five species are added to the known avifauna of mainland North
45 citations
44 citations
TL;DR: Currey's (1974) radiocarbon dates seem to solve the problem of the age of the type Temple Lake till; that is, it predates the Altithermal as discussed by the authors.
Abstract: Currey's (1974) radiocarbon dates seem to solve the problem of the age of the type Temple Lake till; that is, it predates the Altithermal. Our work in the same cirque, however, suggests that his subdivision of the type Temple Lake till into inner and outer units of "substadial" rank can not be substantiated, and that there exists a heretofore unrecognized till that possibly is equivalent to the Audubon till of the Colorado Front Range. Furthermore, we feel that the relative age dating criteria he presents to characterize the tills are not sufficiently detailed to provide workers with data useful for differentiating tills within the cirque, and for suggesting correlations within the Rocky Mountain region. Data on relative age dating criteria that better serve these goals are lichen sizes and percent lichen cover, boulder weathering (percentage of boulders weathered and pitted, depths of pits, and thickness of weathering rinds), the presence and thickness of a surficial loess mantle, depth of soil oxidation, and soil color.
38 citations
TL;DR: Temperature-related photosynthetic and respiratory acclimation responses were examined in alpine, subarctic, and bog populations of Ledum groenlandicum Oeder, a widespread ericaceous shrub species, and populations differed markedly in their potentials for net photosynthesis and dark respiratory Acclimation.
Abstract: Temperature-related photosynthetic and respiratory acclimation responses were examined in alpine, subarctic, and bog populations of Ledum groenlandicum Oeder, a widespread ericaceous shrub species. Acclimation responses to temperature were measured both after 12- to 16-week exposures to either cool (15? C light - 10?C dark) or warm (30?C light - 25?C dark) thermal regimes and again after each of a series of 2-week exposures to new thermal regimes. Dark respiratory rates were decreased by warm acclimation and increased by cool acclimation. These shifts in rates were frequently completed within 2 weeks in a new thermal regime. Maximal net photosynthetic rates generally did not differ significantly among either populations or thermal regimes; however, the temperature for maximal net photosynthesis in each population was increased to 25?C by warm acclimation and decreased to 20?C by cool acclimation. Net photosynthetic rates were increased at cool temperatures by cool acclimation and increased at warm temperatures by warm acclimation. In contrast to respiratory responses, these photosynthetic acclimation shifts were not completed within 2 weeks in a new thermal regime. Ledum groenlandicum populations differed markedly in their potentials for net photosynthetic and dark respiratory acclimation. Alpine and subarctic populations acclimated to greater degrees than their continental and maritime bog counterparts.
TL;DR: In this paper, it was shown that the type of Temple Lake moraine is pre-Neoglacial, as originally suspected; however, the name Temple Lake has gen- probably correlative with the Temple Lake erally been applied to the initial, post-Altither-stade of Neoglaciation recognized elsewhere in mal, stade of NEoglacia.
Abstract: When originally described in the 1940s the evidence for this includes a minimum limiting type Temple Lake moraine was regarded as date of 6,500 + 230 14C years BP from the base probably of latest Wisconsin, or late preclimatic of a bog on the type moraine. A group of optimum, age. In subsequent stratigraphic moraines upvalley from the type moraine is usage, however, the name Temple Lake has gen- probably correlative with the Temple Lake erally been applied to the initial, post-Altither- stade of Neoglaciation recognized elsewhere in mal, stade of Neoglaciation. The present study the Rocky Mountains. Possible revisions of glaindicates that the type Temple Lake moraine is cial stratigraphic nomenclature are discussed. indeed pre-Neoglacial, as originally suspected;
TL;DR: In this article, measurements of seasonal frost heave and penetration were conducted on frost boils occupying the tread of a windswept, snow free, turf-banked lobe just above tree line in the Colorado Front Range.
Abstract: Measurements of seasonal frost heave and frost penetration were conducted on frost boils occupying the tread of a windswept, snowfree, turf-banked lobe just above tree line in the Colorado Front Ra...
TL;DR: In this article, the needle ice stripes on the ground in southwestern British Columbia and in New Zealand were observed to develop parallel to the shadows cast by the sun when needle ice, with its soil cap, thaws and collapses.
Abstract: Observations have been carried out on needle ice striped ground in southwestern British Columbia and in New Zealand. The stripe orientations are shown to develop parallel to the shadows cast by the sun when the needle ice, with its soil cap, thaws and collapses. Differential thaw of the needle ice, and adhesion of some unsupported particles of the soil cap
TL;DR: The internal structure of humgrows on different parts of the hummocks suggests periodic movements of soil by the top of a tree is vegetated by plants cryoturbation, and the absence of trees on that have no roots (lichens, mosses) or by hummock tops is attributed to short-lived plants as mentioned in this paper.
Abstract: Earth hummocks occur on vast areas of trees in the mature forests lean away from the perennially frozen mineral soils in the western hummocks as a result of severe and repeated Canadian subarctic regions. Different vegetation ground heaving. The internal structure of humgrows on different parts of the hummocks. The mocks suggests periodic movements of soil by tops of the hummocks are vegetated by plants cryoturbation, and the absence of trees on that have no roots (lichens, mosses) or by hummock tops is attributed to the same process short-lived plants. Trees seldom grow on humand to somewhat droughty conditions caused mock tops, occurring mainly on the sides of by the pronounced microrelief. hummocks or in interhummock troughs. Most
TL;DR: In this article, rates of movement of nonsorted stripes on slopes of very low angle (2 to 4°) were measured over a 3-year period, 1969 to 1972, at Sachs Harbour in southern Banks Island.
Abstract: Rates of movement of nonsorted stripes on slopes of very low angle (2 to 4°) were measured over a 3-year period, 1969 to 1972, at Sachs Harbour in southern Banks Island. Average annual subsurface m...
TL;DR: In this article, logbooks and journals of American and British whalers and of Hudson's Bay Company vessels were used to reconstruct the summer months of the 18th century. But they did not consider the weather conditions.
Abstract: Logbooks and journals of American and British whalers and of Hudson's Bay Company vessels are used to reconstruct the summer
TL;DR: Alpine plants have probably evolved at different times in various groups, although the explicable in terms of environmental instability is not the same Various factors involved in the origin and conin all families are discussed as discussed by the authors.
Abstract: Alpine plants have probably evolved at dif- but less than many other floras which may be ferent times in various groups, although the explicable in terms of environmental instability. tendency to develop alpine taxa is not the same Various factors involved in the origin and conin all families. Their diversity is considerable tinued existence of alpine floras are discussed.
TL;DR: The alpine environment is an island-like habitat of conditions which are determined by six climatic factors, and any one of four causes may exterminate the species or the ecosystem as discussed by the authors.
Abstract: The alpine environment is an island-like habitat of conditions which are determined by six climatic factors. It forms a series of marginal situations characterized by strong fluctuations. These habitats are similar everywhere, although the northern mountains show a low degree of insularity due to influences of the Pleistocene as compared to the older tropical highlands. The populations are frequently small, and they fluctuate heavily, and any one of four causes may exterminate the species or the ecosystem. The complete absence of true high altitude or latitude elements in the mountain fauna of northwestern Europe, and disjunct distributions of high altitude invertebrates elsewhere, may be caused by such exterminations followed by the lack of sources for reinvasion.
TL;DR: In this article, four years of data from an automatic weath- terior valleys and the arctic coast was used to estimate the annual precipitation of Brooks Range, Alaska, which is much higher than that at any multaneous and long-term observations at the other station in the region and considerably nearer permanent meteorological stations.
Abstract: Four years of data from an automatic weath- terior valleys and the arctic coast. In particular, er station at an altitude of 2,275 m in the the estimated annual precipitation of approxiBrooks Range, Alaska, are compared with si- mately 500 mm is much higher than that at any multaneous and long-term observations at the other station in the region and considerably nearer permanent meteorological stations. This higher than other estimates for the higher part high level location is found to vary greatly in of the Brooks Range. temperature and wind regime from both the in
TL;DR: Leaf photosynthetic measurements using a portable 14CO2 field system were carried out and leaf relative growth rates, Rl, were determined at different leaf positions of three alpine plant species throughout the growing season to determine Ontogenetic timing of these alpine species.
Abstract: Leaf photosynthetic measurements using a portable 14CO2 field system were carried out and leaf relative growth rates, Rl, were determined at different leaf positions of three alpine plant species throughout the growing season. Initially there was a period of high RI associated with a period of high or increasing photosynthetic activity. Following this stage was a long period of no net change in length of the living leaf with photosynthetic activity eventually exhibiting a steady decrease. The final ontogenetic stage was a period of negative Rs denoting leaf senescence which was associated with a marked decline in leaf CO2 uptake. Ontogenetic timing of these alpine species is geared with the surge and decline of individual leaf photosynthetic activity so that one to several leaves operating at near maximal photosynthetic capacity for existing conditions are always maintained during the growing season for each plant.