C4 grasses from the boreal forest region of northwestern Canada

1988 ◽  
Vol 66 (12) ◽  
pp. 2424-2430 ◽  
Author(s):  
A. G. Schwarz ◽  
R. E. Redmann
Keyword(s):  
Boreal Forest ◽  
High Irradiance ◽  
Published Data ◽  
Kranz Anatomy ◽  
The North ◽  
Forest Region ◽  
Geothermal Activity ◽  
The Mean ◽  
Distichlis Stricta ◽  
Boreal Climate

Six C4 grasses (Distichlis stricta, Muhlenbergia glomerata var. cinnoides, M. mexicana, M. richardsonis, Spartina gracilis, S. pectinata) were found in grassy openings in the boreal forest of northwestern Canada. High carbon isotope ratios and Kranz anatomy confirmed that these northern populations are functionally C4 grasses. Muhlenbergia mexicana was assumed to be a C4 grass on the basis of published data. Recent collections of C4 plants tended to have more negative δ13C values than older collections from northern locations, which may reflect decreases in δ13C of atmospheric CO2 over time. In general, northern C4 species had lower δ13C values than those reported for their southern counterparts. The boreal climate in the north supports C4 species only where the mean minimum temperature for July is at least 7.5 °C. C4 grasses were found in microsites warmed by high irradiance or geothermal activity; many of the sites had saline substrates. Northern C4 populations are rare and unique in the boreal flora and deserve special protection.

Kraft Pulping and Specific Gravity in the Uppermost Stem of Fertilized Balsam Fir

1975 ◽  
Vol 5 (3) ◽  
pp. 399-402 ◽  
Author(s):  
J. D. Gagnon ◽  
K. Hunt
Keyword(s):  
Specific Gravity ◽  
Boreal Forest ◽  
Kraft Pulping ◽  
Balsam Fir ◽  
Pulp Yield ◽  
Kraft Process ◽  
Forest Region ◽  
The Mean ◽  
Boreal Forest Region

Samples of five pairs of fertilized and non-fertilized 60-year-old natural balsam fir (Abiesbalsamea (L.) Mill.) growing in the Quebec boreal forest region were pulped by the kraft process and the specific gravity was measured. Analyses carried out 7 years after treatment on the last seven terminal internodes revealed the mean pulp yield of trees fertilized exceeded that of non-fertilized by 7%, while the mean specific gravity was about 6% lower.

Using Landsat data to assess fire and burn severity in the North American boreal forest region: an overview and summary of results

2008 ◽  
Vol 17 (4) ◽  
pp. 443 ◽  
Author(s):  
Nancy H. F. French ◽  
Eric S. Kasischke ◽  
Ronald J. Hall ◽  
Karen A. Murphy ◽  
David L. Verbyla ◽  
...  
Keyword(s):  
Boreal Forest ◽  
North American ◽  
Boreal Forests ◽  
Forest Succession ◽  
Fire Effects ◽  
Burn Severity ◽  
The North ◽  
Forest Region ◽  
Post Fire Effects ◽  
Boreal Forest Region

There has been considerable interest in the recent literature regarding the assessment of post-fire effects on forested areas within the North American boreal forest. Assessing the physical and ecological effects of fire in boreal forests has far-reaching implications for a variety of ecosystem processes – such as post-fire forest succession – and land management decisions. The present paper reviews past assessments and the studies presented in this special issue that have largely been based on the Composite Burn Index and differenced Normalized Burn Ratio (dNBR). Results from relating and mapping fire/burn severity within the boreal region have been variable, and are likely attributed, in part, to the wide variability in vegetation and terrain conditions that are characteristic of the region. Satellite remote sensing of post-fire effects alone without proper field calibration should be avoided. A sampling approach combining field and image values of burn condition is necessary for successful mapping of fire/burn severity. Satellite-based assessments of fire/burn severity, and in particular dNBR and related indices, need to be used judiciously and assessed for appropriateness based on the users’ need. Issues unique to high latitudes also need to be considered when using satellite-derived information in the boreal forest region.

scholarly journals The Flow through the Gulf of Mexico

2019 ◽  
Vol 49 (6) ◽  
pp. 1381-1401 ◽  
Author(s):  
J. Candela ◽  
J. Ochoa ◽  
J. Sheinbaum ◽  
M. López ◽  
P. Pérez-Brunius ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Straits Of Florida ◽  
The North ◽  
Astronomical Tide ◽  
Flow Through ◽  
Sverdrup Transport ◽  
The Mean ◽  
Yucatan Channel ◽  
Range Variation

AbstractFour years (September 2012 to August 2016) of simultaneous current observations across the Yucatan Channel (~21.5°N) and the Straits of Florida (~81°W) have permitted us to investigate the characteristics of the flow through the Gulf of Mexico. The average transport in both channels is 27.6 Sv (1 Sv = 106 m3 s−1), in accordance with previous estimates. At the Straits of Florida section, the transport related to the astronomical tide explains 55% of the observed variance with a mixed semidiurnal/diurnal character, while in the Yucatan Channel tides contribute 82% of the total variance and present a dominant diurnal character. At periods longer than a week the transports in the Yucatan and Florida sections have a correlation of 0.83 without any appreciable lag. The yearly running means of the transport time series in both channels are well correlated (0.98) and present a 3-Sv range variation in the 4 years analyzed. This long-term variability is well related to the convergence of the Sverdrup transport in the North Atlantic between 14.25° and 18.75°N. Using 2 years (July 2014–July 2016) of simultaneous currents observations in the Florida section, the Florida Cable section (~26.7°N), and a section across the Old Bahama Channel (~78.4°W), a mean northward transport of 28.4, 31.1, and 1.6 Sv, respectively, is obtained, implying that only 1.1 Sv is contributed by the Northwest Providence Channel to the mean transport observed at the Cable section during this 2-yr period.

Bankarization in the first European cities with an equal number of Muslim and Christian inhabitants

2017 ◽  
Vol 10 (4) ◽  
pp. 554-580
Author(s):  
Miguel Ángel Pérez-Castro ◽  
Miguel Ángel Montero-Alonso ◽  
Akram Abderrahman-Azaar
Keyword(s):  
North Coast ◽  
Content Type ◽  
European Cities ◽  
The North ◽  
Financial Depth ◽  
Financial Framework ◽  
European Banks ◽  
The Mean ◽  
Different Cultures ◽  
Near Future

Purpose This paper aims to analyze the situation of the financial system in the Spanish-governed cities of Melilla and Ceuta, Christian and Muslim cities located on the north coast of Africa, and compared it with the mean bankarization level in the rest of Spain in 2000-2015. Design/methodology/approach Although different calculation methods have been proposed, most authors agree that the bankarization level of a country or a territory reflects the development of the society as a whole and has a positive correlation with economic growth. The indicators of financial depth proposed by these researchers are not only the ratio between variables such as loans, deposits, etc., but also the ratios of these variables to the population and the gross domestic product (GDP) of the country or territory. Findings The results obtained revealed that there are differences between these two North African Spanish cities. Furthermore, the financing gap between the mean bankarization levels of these cities and those of mainland Spain was found to be even larger than most of the other economic indicators (GDP per capita and the unemployment rate). Practical implications The authors are convinced that the manuscript is a contribution of great interest for serving pilot experience in cities wishing to offer a development of traditional banking and Islamic banking. The paper should be of interest to readers in the areas of finance systems and commercial banks where two different cultures coexist. Originality/value This is the first research study on the financial framework of European cities whose populations have an approximately equal percentage of Christians and Muslims. The data reflected the existence of savings and loan methods parallel to conventional banking. The conclusion was that in the near future, it would be advisable for European banks to take into account the cultural customs and religious practices of potential Muslim clients.

scholarly journals On tho proportions of the prevailing winds, the mean temperature, and depth of rain in the climate of London, computed through a cycle of Eighteen Years, or periods of the Moon’s declination

1843 ◽  
Vol 4 ◽  
pp. 300-300
Keyword(s):  
The Moon ◽  
Fair Weather ◽  
North West ◽  
West Wind ◽  
North East ◽  
East Wind ◽  
The North ◽  
The Common ◽  
The Mean ◽  
Solar Influence

In this paper the author investigates the periodical variations of the winds, rain and temperature, corresponding to the conditions of the moon’s declination, in a manner similar to that he has already followed in the case of the barometrical variations, on a period of years extending from 1815 to 1832 inclusive. In each case he gives tables of the average quantities for each week, at the middle of which the moon is in the equator, or else has either attained its maximum north or south declination. He thus finds that a north-east wind is most promoted by the constant solar influence which causes it, when the moon is about the equator, going from north to south; that a south-east wind, in like manner, prevails most when the moon is proceeding to acquire a southern declination ; that winds from the south and west blow more when the moon is in her mean degrees of declination, going either way, than with a full north or south declination ; and that a north-west wind, the common summer and fair weather wind of the climate, affects, in like manner, the mean declination, in either direction, in preference to the north or south, and most when the moon is coming north. He finds the average annual depth of rain, falling in the neighbourhood of London, is 25’17 inches.

PREDATION BY INSECTS AND SPIDERS INHABITING COLONIAL WEBS OF HYPHANTRIA CUNEA

1972 ◽  
Vol 104 (8) ◽  
pp. 1197-1207 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Population Dynamics ◽  
Nova Scotia ◽  
North America ◽  
Population Density ◽  
New Brunswick ◽  
Numerical Response ◽  
Initial Number ◽  
Hyphantria Cunea ◽  
The North ◽  
The Mean

AbstractThe number of predators inhabiting nests of Hyphantria cunea Drury was recorded annually for 13 years in four areas in New Brunswick and two areas on the coast of Nova Scotia. The most common groups were the pentatomids and spiders, which sometimes reproduced within the nests, but the mean number per nest was low in relation to the number of H. cunea larvae in the colonies. The rate of predation on fifth-instar larvae was low. Small or timid predators appeared to prey largely on moribund larvae or small saprophagans during the principal defoliating instars of H. cunea.No relationship could be detected between the number of larvae reaching the fifth instar and the number of predators in the colony; nor could any functional or numerical response of the predators to either the initial number of larvae per colony or the population density of colonies be found. It is concluded that the influence of the nest-inhabiting predators is small and relatively stable, and may be treated as a constant in the development of models to explain the population dynamics of H. cunea.H. cunea is a pest in parts of Europe and Asia, where it has been accidentally introduced from North America. The introduction to other continents of the North American predator, Podisus maculiventiis (Say), is discussed briefly.

scholarly journals Prevalence of multidrug-resistant Acinetobacter baumannii in a critical care setting: A tertiary teaching hospital experience

2021 ◽  
Vol 9 ◽  
pp. 205031212110011
Author(s):  
Thabit Alotaibi ◽  
Abdulrhman Abuhaimed ◽  
Mohammed Alshahrani ◽  
Ahmed Albdelhady ◽  
Yousef Almubarak ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Mortality Rate ◽  
Acinetobacter Baumannii ◽  
Care Setting ◽  
Multidrug Resistant ◽  
University Hospital ◽  
Published Data ◽  
Tertiary Teaching ◽  
The Mean

Background: The management of Acinetobacter baumannii infection is considered a challenge especially in an intensive care setting. The resistance rate makes it difficult to manage and is believed to lead to higher mortality. We aim to investigate the prevalence of Acinetobacter baumannii and explore how different antibiotic regimens could impact patient outcomes as there are no available published data to reflect our population in our region. Methods: We conducted a retrospective review of all infected adult patients admitted to the intensive care unit at King Fahad University Hospital with a confirmed laboratory diagnosis of Acinetobacter baumannii from 1 January 2013 until 31 December 2017. Positive cultures were obtained from the microbiology department and those meeting the inclusive criteria were selected. Variables were analyzed using descriptive analysis and cross-tabulation. Results were further reviewed and audited by blinded co-authors. Results: A comprehensive review of data identified 198 patients with Acinetobacter baumannii. The prevalence of Acinetobacter baumannii is 3.37%, and the overall mortality rate is 40.81%. Our sample consisted mainly of male patients, that is, 68.7%, with a mean age of 49 years, and the mean age of female patients was 56 years. The mean age of survivors was less than that of non-survivors, that is, 44.95 years of age. We observed that prior antibiotic use was higher in non-survivors compared to survivors. From the review of treatment provided for patients infected with Acinetobacter baumannii, 65 were treated with colistin alone, 18 were treated with carbapenems, and 22 were treated with a combination of both carbapenems and colistin. The mean length of stay of Acinetobacter baumannii–infected patients was 20.25 days. We found that the survival rates among patients who received carbapenems were higher compared to those who received colistin. Conclusion: We believe that multidrug-resistant Acinetobacter baumannii is prevalent and associated with a higher mortality rate and represents a challenging case for every intensive care unit physician. Further prospective studies are needed.

scholarly journals Different trends between extreme and median surface aerosol extinction coefficients over China inferred from quality controlled visibility data

2017 ◽  
Author(s):  
Jing Li ◽  
Chengcai Li ◽  
Chunsheng Zhao
Keyword(s):  
Northwest China ◽  
Positive Trend ◽  
Median Surface ◽  
Aerosol Extinction ◽  
Significance Level ◽  
The North ◽  
Synoptic Conditions ◽  
The Mean ◽  
Mean Trend ◽  
Year 2000

Abstract. Although the temporal changes of aerosol properties have been widely investigated, the majority focused on the averaged condition without much emphasis on the extremes. However, the latter can be more important in terms of human health and climate change. This study uses a previously validated, quality-controlled visibility dataset to investigate the long-term trends of extreme surface aerosol extinction coefficient (AEC) over China, and compare them with the median trends. Two methods are used to independently evaluate the trends, which arrive at consistent results. The sign of extreme and median trends are generally coherent, whereas their magnitudes show distinct spatial and temporal differences. In the 1980s, an overall positive trend is found throughout China with the extreme trend exceeding the mean trend, except for Northwest China and the North China Plain. In the 1990s, AEC over Northeast and Northwest China starts to decline while the rest of the country still exhibits an increase. The extreme trends continue to dominate in the south while it yields to the mean trend in the north. After year 2000, the extreme trend becomes weaker than the mean trend overall in terms of both the magnitude and significance level. The annual trend can be primarily attributed to winter and fall trends. The results suggest that the decadal changes of pollution in China may be governed by different mechanisms. Synoptic conditions that often result in extreme air quality changes might dominate in the 1980s, whereas emission increase might be the main factor for the 2000s.

scholarly journals Optical Properties of Dissolved Organic Matter in Finnish and Estonian Lakes

2003 ◽  
Vol 34 (4) ◽  
pp. 361-386 ◽  
Author(s):  
L. Sipelgas ◽  
H. Arst ◽  
K. Kallio ◽  
A. Erm ◽  
P. Oja ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Natural Waters ◽  
Mean Value ◽  
Published Data ◽  
Optical Parameters ◽  
Exponential Approximation ◽  
Absorption Coefficients ◽  
Specific Absorption ◽  
The Mean

The main objective of the present study is to test various methods for describing the absorption spectra of coloured dissolved organic matter (CDOM) and to determine the numerical values of some optical parameters of CDOM in lakes with diverse water quality. First, the parameters of an exponential model in different spectral intervals were determined. In addition, the suitability of some other models for the approximation of CDOM spectra was estimated. Specific absorption coefficients of CDOM were calculated from the absorption coefficients and dissolved organic carbon (DOC) concentrations. The experimental initial data were differences between spectral attenuation coefficients of filtered and distilled water. Two datasets were used: 1) for 13 Estonian and 7 Finnish lakes (altogether 404 spectra between 350 and 700 nm) measured by the Estonian Marine Institute (EMI); 2) for 10 Finnish lakes (73 spectra) measured by the Finnish Environment Institute (FEI). The spectra of CDOM absorption coefficients (aCDOM) were calculated from experimental data taking into account the correction due to scattering properties of colloids in the filtered water. The total content of CDOM in natural waters of Estonian and Finnish lakes was expressed by means of aCDOM at the wavelength of 380 nm. It varied significantly, from 0.71 to 19.5 m−1, the mean value (of all the investigated lakes) being around 6.6 m−1. Slopes of the exponential approximation varied widely, from 0.006 to 0.03 nm−1. Averaged over all lakes values of slope for the interval 380-500 nm obtained from the EMI dataset are close to those obtained from the FEI dataset: from 0.014 nm−1 (without correction) to 0.016-0.017 nm-1 (with different types of correction). These results are in good correspondence with most published data. Attempts to describe the spectra in the region of 350-700 nm by means of hyperexponential functions (∽ exp(-αλη)) show that: (1) η < 1 (in the case of traditional exponential approximation η = 1); (2) a promising idea is to seek the best fit only for wavelengths λ > λ1, where λ1 will be chosen taking into account the real shape of aCDOM spectra. The mean value of the specific absorption coefficient (a*CDOM) at the wavelength 380 nm obtained in this study (0.44 L mg−1 m−1) is close to the values published in the literature, if we assume that a*CDOM (380) is calculated using the data of dissolved organic matter (DOM). The optically non-active fraction of DOM in our study was high and therefore a*CDOM (380) was considerably higher (1.01 L mg−1 m−1) than a*CDOM (380). The results of the present work could be used in the modeling of underwater light field as well as in the interpretation of radiation measurements and optical remote sensing results.

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