Wyniki wyszukiwania

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Pozywienie roslinne ludow zbieracko-lowieckich we wschodniej Saharze okolo 8 tysiecy lat temu

100%

Wasylikowa K.

Działalność Naukowa PAN. Wybrane Zagadnienia

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1998

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tom 05

74-75

2

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Kształt barchanów jako wskaźnik reżimu wiatru na przykładzie Sahary Zachodniej Maroko

100%

Dluzewski M., Biejat K.

Prace i Studia Geograficzne

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2012

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tom 49

Barchans are characterized by a symmetric shape independently of their stage of development and the axis of symmetry parallels to the dominant wind direction. However, shape of the dunes can be modified by several factors, among which most important are: change of wind regime, dune collisions or interaction of closely spaced dunes, ground surface relief, asymmetric sediment supply. The aim of the study was to analyze the impact of short-term (diurnal) and long-term (seasonal) changes in wind direction and velocity on shape of barchan dunes. The study was conducted in southern Moroccan area of Western Sahara, between Tarfaya and Laâyoune. This area is characterised by significant variability of active wind (RDP/DP=0,66) which is unfavourable for barchans development. Measurements were conducted in two spring seasons of 2011 and 2012 and two autumn seasons of 2007 and 2011. 52 isolated barchans were selected for detailed studies. Based on GPS-RTK measurements, precise 3D models of the landforms were obtained allowing the detailed analysis of dune shapes. Changes of basie morphological parameters were analyzed as well as shape changes occurring the windward slope and within dunes horns. The shapes of the barchans were correlated with the short-term and the long-term wind regime. It was found that basic morphological parameters are not good indicators of wind variability, with the exception of barchan horns lengths which change according to the seasonal wind regime. Short-term wind regime changes are well registered by: i) "collars" developing along the dune crestlines, ii) "tongues" developing at the ends of dune horns and iii) location of the dune apex. On the other hand, beaded horns testify for very strong wind. I was found, that mentioned features develop and undergo modification during first days or even hours of changed wind regime. The analyzes of barchan shapes, performed in different seasons, proved that even a several-month long period of highly diversified wind regime does not change basie shape of the barchans. Therefore, it can be inferred that barchans development does not depend exclusively on wind regime.

3

Źródło wilgoci w barchanach Sahary Zachodniej

75%

Dluzewski M., Zmudzka E., Woronko D., Biejat K.

Prace i Studia Geograficzne

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2012

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tom 49

The aim of the study was to determine the impact of climatic and meteorological conditions on aeolian sand transport within barchans. The study area was located at Western Sahara, around the towns of Tarfaya and Laâyoune. Particular attention was paid to the factors that increase the moisture content of the surface and subsurface layers of sand dunes. It could be one of the important factors to have an influence on threshold wind velocity. Western Sahara dune fields are situated in the zone of the dominant wind direction from the northern sector, which determines the barchan dunes shape and orientation, as well as the supply of moisture from the Atlantic Ocean. The results of investigations confirm that dunes receive quite a lot of moisture from rainfall and such phenomena as fog as well. Studies have confirmed that the water supply from the fog is comparable to, or even exceeds the amount of water from rainfall in the area. Wetted surface layer reduces the transport of aeolian material, even in case of a wind speed greater than 4-5 ms⁻¹. The presence of fog and dew does not affect the moisture of the deeper sand layers, which occurs after rainfall. Analysis of aeolian sand transport within the barchan dunes in the areas such a Western Sahara, should not be therefore limited to the measurement of wind speed and its direction. It must include the investigations on other meteorological elements, especially air temperature and humidity conditions, responsible for the amount of atmospheric deposits on the dune surface.

4

Rolnicze wykorzystanie wód na Saharze

75%

Walewski A.

Prace i Studia Geograficzne

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2010

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tom 44

The Sahara has exceptionally unfavourable natural conditions for farming. The extremely low precipitation and the high prevailing temperature allow for plant cultivation only in artificial irrigation conditions. The author discusses the regions' water resources (precipitation, surface and underground waters) and describes various ways of their use for agriculture. He also enumerates the main advantages and limitations of the technologies used, both traditional and modern, while placing special emphasis on the natural conditions of irrigated agriculture.

5

Elements of the vascular flora collected in France, Spain and West Africa during the Polish Scientific Expedition to Equatorial Africa 1974-75

75%

Herezniak J.

Fragmenta Floristica et Geobotanica

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1999

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tom 44

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nr 2

6

Czy Sahara i Syberia wyludniają się? Zmiany zaludnienia w obszarach o niesprzyjających do życia warunkach środowiska przyrodniczego

63%

Wites T.

Czasopismo Geograficzne

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2016

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tom 87

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nr 1

7

Modelling the transport of Saharan dust toward the Mediterranean region: an important issue for its ecological implications

63%

Riccio A., Chianese E., Tositti L., Baldacci D., Sandrini S.

Ecological Questions

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2009

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tom 11

Airborne particulate matter (PM) is presently an environmental problem of primary concern, whose role in air quality, climatic and ecological issues is well recognized, though still a matter of extensive investigations (Intergovernmental Panel on Climate Change, 2007).It is of great scientific interest to detect sources of atmospheric particulate matter and quantify their influence on the global and local scales. Unfortunately, emissions are usually not directly available, while PM concentration time series are experimentally accessible, so that the problem often consists in "inverting" these data to determine the region of influence that caused the measured concentration. In this paper we are concerned with an alternative approach to inverse modeling based on backward trajectory analysis (BTA); this approach has the potential to overcome some limitations associated with traditional BTA.We apply this method to the analysis of PM time series from the Monte Cimone observatory, hereafter MCT, a high altitude station on the top of the Italian Northern Apennines, with the aim of estimate the contribution of Saharan dust transport on PM concentration levels registered in the Mediterranean region.

8

Mechanical and chemical alterations of skeletal tissues in a recent Saharian accumulation of faeces from Vulpes rueppelli [Carnivora, Mammalia]

63%

Denys C., Kowalski K., Dauphin Y.

Acta Zoologica Cracoviensia

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1992-1993

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tom 35

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nr 2

9

Uczmy się od Tuaregów - relacja z wycieczki szkolnej

63%

Olesiak M.

Bociek. Biuletyn Klubu Przyrodników

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2004

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nr 1[77]

10

New early Pliocene owls from Langebaanweg, South Africa, with first evidence of Athene south of the Sahara and a new species of Tyto

51%

Pavia M., Manegold A., Haarhoff P.

Acta Palaeontologica Polonica

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2015

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tom 60

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nr 4

The fossiliferous Upper Varswater Formation at Langebaanweg (South Africa) produced remains of at least five species of owls (Strigiformes). Tyto richae sp. nov. is the first palaeospecies of Tytonidae described from an African fossil site, though indeterminate remains referable to the genus Tyto are known from the Middle Miocene of Morocco, the early Pliocene of Ethiopia, and the Pliocene of Tanzania. Athene inexpectata sp. nov. is not only the earliest documented fossil evidence for the genus worldwide, but also the first record of a species of Athene in Africa south of the Sahara. Proportions of its hind limb indicate that At. inexpectata sp. nov. probably has been as terrestrial as its modern relative At. cunicularia. A few additional remains represent the earliest fossil evidence for the genera Asio and Bubo on the African continent, though the poor preservation of these bones prevents more detailed identifications. A distal tibiotarsus of a small owl about the size of At. inexpectata sp. nov. indicates the presence of a fifth, as yet indeterminate, species of owl at Langebaanweg. Biogeographical and palaeoecological implications of this assemblage of owls are discussed.

11

Projektowane morze w Saharze algiersko-tunetańskiej i jego znaczenie (Dokończenie)

51%

Czerny F.

Wszechświat

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1882

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tom 1

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nr 12

12

Projektowane morze w Saharze algiersko-tunetańskiej i jego znaczenie

51%

Czerny F.

Wszechświat

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1882

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tom 1

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nr 11

13

Egg size variation and breeding characteristics of the Black-winged Stilt Himantopus himantopus in a Saharan oasis

51%

Adamou A.-E., Kouidri M., Chabi Y., Skwarska J., Banbura J.

Acta Ornithologica

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2009

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tom 44

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nr 1

Different aspects of the breeding biology of the Black-winged Shit were studied in a natural oasis wetland area in the Sahara Desert, the Chott of Aïn El Beïda, near Ouargla, E Algeria in 2004-2007. In this wetland the water level is independent of rainfall and Stilts start egg laying when average daily temperature increases to ca. 15°C, mostly in April-May, with no significant differences between years. Complete clutches usually consist of 4 eggs but 3 egg clutches happen with low frequency (2.9-5.6%). Egg size traits (mass, length, breadth and volume) tended to decrease from 2004 to 2007, probably due to deteriorating hydrological conditions of the wetland. Within-clutch variability showed both significant repeatability and laying-sequence-dependent differences among eggs, with the final egg being smaller than the clutch mean value. We found that all egg traits studied showed a negative correlation with the date of laying, which seems to be a phenomenon analogous to the seasonal decrease in clutch size, typical of birds with more variable clutch sizes. Hatching tended to be asynchronous, with average clutch hatching time being 1.84 days. The small final egg and hatching asynchrony are typical components of the adaptive brood reduction, the phenomenon not being recorded so far and remaining for future studies on the Black-winged Stilt. These are the first published data on breeding characteristics for any N African population of the Black-winged stilt.

14

Flora of the 8000 years old archaeological site E-75-6 at Nabta Playa, Western Desert, Southern Egypt

51%

Wasylikowa K.

Acta Palaeobotanica

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1997

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tom 37

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nr 2

15

Przyroda nieozywiona Sahary

51%

Pajak J.

Wszechświat

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2009

|

tom 110

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nr 04-06

63-66

16

Rajdowanie nieobiektywnie. W obiektywie

51%

Jozefczyk M.

Konie i Rumaki

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2019

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nr 10

17

Palmy, palmy, czyli konno przez Saharę cz. I

50%

Jozefczyk M., Zawistowski T.

Konie i Rumaki

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2019

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nr 09

18

Parenchymatous tissues from the early Neolithic site E-75-6 at Nabta Playa, western desert, South Egypt

45%

Hather J.

Acta Palaeobotanica

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1995

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tom 35

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nr 1

19

Numerical analysis of charred seeds and fruits from an 8000 years old site at Nabta Playa, western desert, south Egypt

45%

Mitka J., Wasylikowa K.

Acta Palaeobotanica

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1995

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tom 35

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nr 1

20

Plant macroremains from Z'bib N Elias. A subfossil middens from a prehistoric cave in the Hoggar, Central Sahara

45%

Barakat H. N.

Acta Palaeobotanica

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1995

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tom 35

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nr 1

Ograniczanie wyników

Pozywienie roslinne ludow zbieracko-lowieckich we wschodniej Saharze okolo 8 tysiecy lat temu

Kształt barchanów jako wskaźnik reżimu wiatru na przykładzie Sahary Zachodniej Maroko

Źródło wilgoci w barchanach Sahary Zachodniej

Rolnicze wykorzystanie wód na Saharze

Elements of the vascular flora collected in France, Spain and West Africa during the Polish Scientific Expedition to Equatorial Africa 1974-75

Czy Sahara i Syberia wyludniają się? Zmiany zaludnienia w obszarach o niesprzyjających do życia warunkach środowiska przyrodniczego

Modelling the transport of Saharan dust toward the Mediterranean region: an important issue for its ecological implications

Mechanical and chemical alterations of skeletal tissues in a recent Saharian accumulation of faeces from Vulpes rueppelli [Carnivora, Mammalia]

Uczmy się od Tuaregów - relacja z wycieczki szkolnej

New early Pliocene owls from Langebaanweg, South Africa, with first evidence of Athene south of the Sahara and a new species of Tyto

Projektowane morze w Saharze algiersko-tunetańskiej i jego znaczenie (Dokończenie)

Projektowane morze w Saharze algiersko-tunetańskiej i jego znaczenie

Egg size variation and breeding characteristics of the Black-winged Stilt Himantopus himantopus in a Saharan oasis

Flora of the 8000 years old archaeological site E-75-6 at Nabta Playa, Western Desert, Southern Egypt

Przyroda nieozywiona Sahary

Rajdowanie nieobiektywnie. W obiektywie

Palmy, palmy, czyli konno przez Saharę cz. I

Parenchymatous tissues from the early Neolithic site E-75-6 at Nabta Playa, western desert, South Egypt

Numerical analysis of charred seeds and fruits from an 8000 years old site at Nabta Playa, western desert, south Egypt

Plant macroremains from Z'bib N Elias. A subfossil middens from a prehistoric cave in the Hoggar, Central Sahara