| 1. |
- Farahat, Emad, et al.
(författare)
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Phenology, biomass and reproductive characteristics of Calotropis procera (Aiton) WT Aiton in South Cairo, Egypt
- 2016
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Ingår i: Rendiconti Lincei-Scienze Fisiche E Naturali. - : Springer Science and Business Media LLC. - 2037-4631. ; 27:2, s. 197-204
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Tidskriftsartikel (refereegranskat)abstract
- Phenology is a major trait structuring life history strategies and its role in shaping plant invasions that has increasing attention. The present study aimed to examine the role of phenology, reproductive, and morphological attributes of Calotropis procera in colonizing urban areas, besides assessing its biomass and developing allometric regression equation for prediction of its biomass. Sixty-three permanent quadrats were selected to represent the distribution of C. procera in urban habitats at South Cairo Province, Egypt. The present study revealed significant positive correlation between fruiting phase of the species and temperature, as well as the vegetative phase and precipitation. C. procera is characterized by continuous flowering for 8 months, with a peak in April and May, which help in reproductive success of the species. It had its highest biomass in November (439 kg ha(-1)), but the lowest in March (343 kg ha(-1)), with an annual mean of 388 kg ha(-1). The linear regression based on plant volume as an independent variable was found to be the best fit for biomass prediction, with the highest coefficient of determination (R (2) = 0.81). The above-ground biomass of this plant encourages its potential use as a renewable energy source. Our study suggests that C. procera has efficient plastic phenological and functional attributes that may enable it to dominate many ecosystems in the future. Efficient management plans are needed to mitigate the risk of this plant on other ecosystems and conserve other native species.
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| 2. |
- Ianniello, A., et al.
(författare)
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Air-snow exchange of reactive nitrogen species at Ny-lesund, Svalbard (Arctic)
- 2016
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Ingår i: Rendiconti Lincei-Scienze Fisiche E Naturali. - : Springer Science and Business Media LLC. - 2037-4631. ; 27:supplement 1, s. 33-45
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of atmospheric concentrations and fluxes of reactive nitrogen (NO, NO2, HNO3, NO3 (-) (fine) and NO3 (-) (coarse)) above the snow surface were performed from 29 March to 30 April 2010 at Ny-lesund, Svalbard. Determinations of chemical and physical properties of snow were also carried out. Both NO and NO2 showed clear diurnal cycles with noontime maxima and nighttime minima. Significant emission fluxes of NO and NO2 were observed, reaching noontime values up to 19.42 and 25.20 pmol/m(2) s, respectively. The snow surface was the source of NO and NO2 but these observed releases were small due to almost alkaline snow environment and chemical forms of snow NO3 (-). Significant deposition fluxes of HNO3, fine and coarse particulate NO3 (-) fluxes were also observed, reaching peak values up to -18.00, -37.80 and -12.50 pmol/m(2) s, respectively, during snowfall events. Measurements of surface snow provided experimental data that the total contribution of dry deposition of these species to the NO3 (-) -N in the snow was about 24 %. However, wet deposition in falling snow seemed to be the major contribution to the nitrate input to the snow.
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| 3. |
- Longo, Emanuela, et al.
(författare)
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Inter- and intra-specific variation in movement behaviour of benthic macroinvertebrates from a transitional habitat : a laboratory experiment
- 2016
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Ingår i: Rendiconti lincei scienze fisiche e naturali. - : Springer Science and Business Media LLC. - 2037-4631. ; 27:2, s. 281-290
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Tidskriftsartikel (refereegranskat)abstract
- The movement behaviour of vagile organisms has long been acknowledged as a key determinant of species distribution and biodiversity patterns. Yet, scant information is available for aquatic invertebrates; in addition, the effects of inter-specific differences in morphology and intra-specific variations in body size have been inadequately investigated. In the present study, the movement behaviour of three crustacean species [Proasellus coxalis and Lekanesphaera hookeri (Isopoda) and Gammarus aequicauda (Amphipoda)] and two gastropod species (Ecrobia ventrosa and Bithynia leachii) dominating the macrobenthic assemblage of a Mediterranean transitional habitat (Giammatteo channel estuary, SE Italy) was analysed under resource-free laboratory conditions. The average path length and speed were determined for individuals encompassing a 16-fold range in body sizes. The scale-independent fractal dimension D was used to quantify the tortuosity of their trajectories. In general, significant differences were observed in movement metrics between crustaceans and gastropods; however, species-specific effects were obscured within each taxonomic group by a strong intra-specific variability. All crustacean species were characterized by a significant negative relationship between body size and path tortuosity; specifically, breaks in the slopes of the regression curve were observed, coinciding with sexual maturation. In contrast, negligible relationships were observed for gastropod species. The results of the study suggest that body size may represent a good predictor of movement behaviour for crustaceans but not for gastropods. Specifically, crucial steps of the biological cycle of amphipods and isopods may reflect on considerable variations in movement metrics. The metabolic and ecological implications of these findings are discussed.
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| 4. |
- Lupi, Angelo, et al.
(författare)
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Multi-seasonal ultrafine aerosol particle number concentration measurements at the Gruvebadet observatory, Ny-lesund, Svalbard Islands
- 2016
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Ingår i: Rendiconti lincei scienze fisiche e naturali. - : Springer Science and Business Media LLC. - 2037-4631. ; 27, s. 59-71
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Tidskriftsartikel (refereegranskat)abstract
- The object of this study was to investigate the different modal behavior of ultrafine aerosol particles collected at the Gruvebadet observatory located in Ny-lesund (Svalbard Islands, 78A degrees 55'N, 11A degrees 56'E). Aerosol particle size distribution was measured in the size range from 10 to 470 nm typically from the beginning of spring to the beginning of fall during four (non-consecutive) years (2010, 2011, 2013 and 2014). The median concentration for the whole period taken into account was 214 particles cm(-3), oscillating between the median maximum in July with a concentration of 257 particles cm(-3) and a median minimum in April with 197 particles cm(-3). The median total number concentration did not present a well-defined seasonal behavior, as shown by contrast looking at the sub/modal number concentration, where distinct trends appeared in the predominant accumulation concentration recorded during April/May and the preponderant concentration of Aitken particles during the summer months. Lastly, the short side-by-side spring 2013 campaign performed at the Zeppelin observatory with a differential mobility particle sizer was characterized by an aerosol concentration mean steady difference between the two instruments of around 14 %, thereby supporting the reliability of the device located at Gruvebadet.
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| 5. |
- Spolaor, A., et al.
(författare)
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Evolution of the Svalbard annual snow layer during the melting phase
- 2016
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Ingår i: Rendiconti Lincei-Scienze Fisiche E Naturali. - : Springer Science and Business Media LLC. - 2037-4631. ; 27:Supplement 1, s. 147-154
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Tidskriftsartikel (refereegranskat)abstract
- Understanding and monitoring the evolution of annual snow is an important aspect of cryosphere research. Changes in physical proprieties such as hardness, presence of melt layers, or the shape and size of crystals can completely modify the robustness, propriety and quality of the snow. Evaluating these changes can inform the study and prediction of avalanches. The annual snow layer is also a sink for several compounds and elements. In the polar environment, many compounds can be accumulated during winter depositions, especially during the polar night. During the spring, the combination of solar radiation and the melting of annual snow can release these compounds and elements into the atmosphere and groundwater. An in-depth investigation of the evolution of the first meter of the annual snow layer was conducted in the glacier of Austre Broggerbreen, Svalbard, between the 27th of March and the 31st of May, in concomitance with the start of the melting phase. The present monitoring study mainly aimed to evaluate changes in the thermal profile and water content during the formation of a new ice layer as well as the re-allocation of the total dissolved salts in the different snow layers.
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