Twenty of the most thermophilous vascular plant species in Svalbard and their conservation state     

Torstein Engelskjøn  Leidulf Lund  Inger Greve Alsos 《Polar research》2003,22(2):317-339

An aim for conservation in Norway is preserving the Svalbard archipelago as one of the least disturbed areas in the Arctic. Information on local distribution, population sizes and ecology is summarized for 20 thermophilous vascular plant species. The need for conservation of northern, marginal populations in Svalbard is reviewed, using World Conservation Union categories and criteria at a regional scale. Thirteen species reach their northernmost distribution in Svalbard, the remaining seven in the western Arctic. Nine species have 1-8 populations in Svalbard and are assigned to Red List categories endangered or critically endangered: Campanula rotundifolia, Euphrasia frigida, Juncus castaneus, Kobresia simpliciuscula, Rubus chamaemorus, Alchemilla glomerulans, Ranunculus wilanderi, Salix lanata and Vaccinium uliginosum , the last four species needing immediate protective measures. Five species are classified as vulnerable: Betula nana, Carex marina ssp. pseudolagopina, Luzula wahlenbergii, Ranunculus arcticus and Ranunculus pallasii . Six species are considered at lower risk: Calamagrostis stricta, Empetrum nigrum ssp. hermaphroditum, Hippuris vulgaris (only occurring on Bjørnøya), Juncus triglumis, Ranunculus lapponicus and Rhodiola rosea . The warmer Inner Arctic Fjord Zone of Spitsbergen supports most of the 20 target species and is of particular importance for conservation. Endangered or vulnerable species were found in a variety of edaphic conditions; thus, several kinds of habitats need protection.  相似文献   

Influence of the Pacific Decadal Oscillation on the climate of theSierra Nevada, California and Nevada     

Larry Benson  Braddock LinsleyJoe Smoot  Scott MensingSteve Lund  Scott StineAndre Sarna-Wojcicki 《Quaternary Research》2003,59(2):151-159

Mono Lake sediments have recorded five major oscillations in the hydrologic balance between A.D. 1700 and 1941. These oscillations can be correlated with tree-ring-based oscillations in Sierra Nevada snowpack. Comparison of a tree-ring-based reconstruction of the Pacific Decadal Oscillation (PDO) index (D’Arrigo et al., 2001) with a coral-based reconstruction of Subtropical South Pacific sea-surface temperature (Linsley et al., 2000) indicates a high degree of correlation between the two records during the past 300 yr. This suggests that the PDO has been a pan-Pacific phenomena for at least the past few hundred years. Major oscillations in the hydrologic balance of the Sierra Nevada correspond to changes in the sign of the PDO with extreme droughts occurring during PDO maxima. Four droughts centered on A.D. 1710, 1770, 1850, and 1930 indicate PDO-related drought reoccurrence intervals ranging from 60 to 80 yr.  相似文献   

Queens as Mothers: the role of the traditional safety net of care and support for HIV/AIDS orphans and vulnerable children in Ghana     

Ragnhild Lund  Samuel Agyei-Mensah 《GeoJournal》2008,71(2-3):93-106

The paper examines the significance of the traditional safety net to provide security and help to orphans and vulnerable children (OVC). (Abbreviation OVC, as conceptualised by UNICEF (2001)). It questions the scenario of societal breakdown due to HIV/AIDS by asking how the traditional safety net operates, nature of solutions to the OVC problem it provides and its sustainability. No geographical region in Ghana has been so affected by the HIV/AIDS pandemic than the Manya Krobo District in Ghana. While analysing the role of the work of the Manya Krobo Queen Mothers’ Association (QMA) and five private caregivers, the perceptions of three OVC are presented: on how it is to be an OVC, what their dreams and hopes are for the future, and their awareness of HIV/AIDS. It is observed that even though the QMA serves as a good role model for how to address the OVC problem, it has its limitations. The traditional extended family system is under pressure, but not about to break down. As the effectiveness of its support will depend on the contribution of the wider Ghanaian society, localised solutions have to be scaled up to make an impact. Thus, the breakdown scenario needs to be nuanced and contextualised. The vulnerability of the local place under study relates to unemployment and migration, economic poverty and social–cultural marginalisation. These factors are intertwined with the HIV/AIDS epidemic.  相似文献   

Relationships between the frequency of farmed Atlantic salmon, Salmo salar L., in wild salmon populations and fish farming activity in Norway, 1989-2004     

Fiske  Peder; Lund  Roar A.; Hansen  Lars P. 《ICES Journal of Marine Science》2006,63(7):1182-1189

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The incidence of reared Atlantic salmon (Salmo salar L.) of fish farm origin at West Greenland     

Hansen  L. P.; Reddin  D. G.; Lund  R. A. 《ICES Journal of Marine Science》1997,54(1):152-155

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Interpretation of the precursor to the 1960 great chilean earthquake as a seismic solitary wave     

Fernando Lund 《Pure and Applied Geophysics》1983,121(1):17-26

Seismic solitary waves may exist. The situation envisaged is that of an elastic layer over a half space where transverse, linearly polarized surface waves—Love waves—propagate. In the long wavelength limit, nonlinearities may compensate dispersion so that localized wave packets can propagate without distortion. A model equation is derived that explicitly exhibits this phenomenon, having among its solutions a strain solitary wave. It is predicted that strains of seismic interest should propagate with the shear wave velocity of the underlying half space, and they should have a wavelength about three orders of magnitude greater than the depth of the top layer. In light of the above considerations the precursor to the 1960 great chilean earthquake recorded with the Pasadena strain seismogram is interpreted as a seismic solitary wave produced by the foreshock that preceded the main shock by about 15 min. It traveled as a surface wave guided by the oceanic crust.  相似文献   

The fine structure of the lower lithosphere underneath the Blue Road profile in northern Scandinavia     

C.-E. Lund 《Tectonophysics》1979,56(1-2)

On the basis of DSS data from the recordings of compressional and shear waves made during the Blue Road shootings in 1972, velocity—depth models for the lower lithosphere are presented. A lid with a velocity of 8.32 km/s was found underneath the Mohorovic̆ić discontinuity. An upper-mantle fine structure consisting of several high- and low-velocity zones was derived. At a depth of 96 km, a P-velocity of 8.5 km/s was reached.A minimum shear-wave velocity of 4.70 km/s has been determined for the uppermost part of the mantle underneath the Mohorovičić discontinuity. This velocity allows a shear low-velocity zone of a few tens of kilometers in the uppermost post of the mantle.  相似文献   

Marine radar ocean wave retrieval’s dependency on range and azimuth     

Björn Lund  Clarence O. Collins  Hans C. Graber  Eric Terrill  Thomas H. C. Herbers 《Ocean Dynamics》2014,64(7):999-1018

The strength of the surface wave signal in marine X-band radar (MR) images strongly depends on range and azimuth (i.e., the angle between antenna look and peak wave direction). Traditionally, MR wave analysis is carried out in a set of rectangular windows covering the radar field of view (FOV). The FOV is typically partially obstructed, e.g., due to the coastline or ship superstructures. Especially for ships that are subject to regular course changes, this results in an increased variability or error associated with wave parameters. Using MR measurements from R/P FLIP, acquired off California during the 2010 US Office of Naval Research (ONR) high resolution air–sea interaction (Hi-Res) experiment, this study quantifies the dependency of the radar-based 2D wave spectrum and parameters on range and azimuth. With the help of reference data from a nearby Datawell Waverider buoy, we propose empirical methods to remove the dependency and we illustrate their efficacy.  相似文献   

A Holocene record of Pacific Decadal Oscillation (PDO)-related hydrologic variability in Southern California (Lake Elsinore,CA)     

M. E. Kirby  S. P. Lund  W. P. Patterson  M. A. Anderson  B. W. Bird  L. Ivanovici  P. Monarrez  S. Nielsen 《Journal of Paleolimnology》2010,44(3):819-839

High-resolution terrestrial records of Holocene climate from Southern California are scarce. Moreover, there are no records of Pacific Decadal Oscillation (PDO) variability, a major driver of decadal to multi-decadal climate variability for the region, older than 1,000 years. Recent research on Lake Elsinore, however, has shown that the lake’s sediments hold excellent potential for paleoenvironmental analysis and reconstruction. New 1-cm contiguous grain size data reveal a more complex Holocene climate history for Southern California than previously recognized at the site. A modern comparison between the twentieth century PDO index, lake level change, San Jacinto River discharge, and percent sand suggests that sand content is a reasonable, qualitative proxy for PDO-related, hydrologic variability at both multi-decadal-to-centennial as well as event (i.e. storm) timescales. A depositional model is proposed to explain the sand-hydrologic proxy. The sand-hydrologic proxy data reveal nine centennial-scale intervals of wet and dry climate throughout the Holocene. Percent total sand values >1.5 standard deviation above the 150–9,700 cal year BP average are frequent between 9,700 and 3,200 cal year BP (n = 41), but they are rare from 3,200 to 150 cal year BP (n = 6). This disparity is interpreted as a change in the frequency of exceptionally wet (high discharge) years and/or changes in large storm activity. A comparison to other regional hydrologic proxies (10 sites) shows more then occasional similarities across the region (i.e. 6 of 9 Elsinore wet intervals are present at >50% of the comparison sites). Only the early Holocene and the Little Ice Age intervals, however, are interpreted consistently across the region as uniformly wet (≥80% of the comparison sites). A comparison to two ENSO reconstructions indicates little, if any, correlation to the Elsinore data, suggesting that ENSO variability is not the predominant forcing of Holocene climate in Southern California.  相似文献   

The incidence of escaped farmed Atlantic salmon, Salmo salar L., in the Faroese fishery and estimates of catches of wild salmon     

Hansen  L. P.; Jacobsen  J. A.; Lund  R. A. 《ICES Journal of Marine Science》1999,56(2):200-206

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