Solos e geomorfologia da borda leste da Península Warszawa, Ilha Rei George, Antártica Marítima

• Autor(a) principal: Bremer, Ulisses Franz
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1593
• topic: Antártica; Criossolos; Solos ornitogênicos; Geomorfologia periglacial; Antarctica; Cryosoils; Ornithogenic soils; Periglacial geomorphology; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

On the eastern Warszawa Peninsula, King Georg Island, penguins (Pygoscelis antarctica) can be seen nesting on the rocky coasts, low moraines on the shoreline and second level, or higher, marine terraces. Thus, ornithogenic soils derived from these bird colonies are generally shallow, presenting phosphatization depth far lower than the ornithogenic soils of Pygoscelis adeliae rookeries, which occupy the higher grounds of the Antarctic Specially Protected Area Western Shore of Admiralty Bay (ASPA 128). Field work and laboratory analysis of ornithogenic soils, between Sphinx Point, inside Admiralty Bay, and Telefon Point, bordering the Bransfield strait, permitted the differentiation of these soils from other ASPA 128 ornithogenic ecosystems. A mosaic of small format aerial photographs taken in 2004, and the interpretation of a 2006 Quickbird satellite image allowed the contrast and geomorphologic classification of the study site. These products also made it possible to outline the main vegetation communities and establish some geoecological relations of the area by modeling the solar radiation using the Solar Analyst function on ArcView 3.2a software. Soil sample chemical analyses from the extreme southern sector of ASPA128 studied profiles presented exceptionally high values for P. Available Mehlich-1 extractable P concentrations reached higher values than those found by Schaefer et al. (2004) in the soils between Thomas Point and Ecology Glacier, near Arctowski Station, as well as those found by Michel et al. (2006), between Ecology Glacier and Sphinx Point, near Copacabana. From Telefon Point, P2 and P3 profiles are noteworthy, showing values for P of 20054.5 mg dm-3 and 8667.9 mg dm-3, respectfully. These values suggest an important reactivity of the phosphate lixiviated solutions of guano interacting with the rocky substrate, under cryoturbation and, thus, intensively fractured and vulnerable to percolation of per descendum solutions. In this way, combining rookery habitat with the shallow soils, permitting the organic matter to accumulate even though part of the material returns to the sea through surface flow channels. These P. antarctica ornithogenic soils also show very high values of exchangeable Na, demonstrating a marine influence due to the exposure of the soil to the beach sea spray or blown inshore. At Uchatka and Demay points, around Paradise Cove, older rookeries present P concentrations a lot lower than the levels found at the current rookeries and, although anomalous to non-ornithogenic soils, maintaining the trend of shallower soils, with the exception of profile D5, the deepest and most developed of the whole dataset. P levels compare to soils of sites that were colonized by P. adeliae at the Arctowski and Copacabana sites. The acidification promoted by weathering and vegetation cover, mainly the angiosperms Deschampsia antarctica and Colobanthus quitensis, frequently associated to bryophytes, is capable of reducing the pH (4.76-5.23) and high solulability forms of Al for the solution. Lichens compose the largest community of flora on the eastern Warszawa Peninsula, in which usneas from the genus Neuropogon make up 7.7% in the studied area. The vegetated areas are predominant in places where the average global radiation values are above the general average. Despite the importance of this flora, 88.1% of the southern sector of the ASPA128 is absent or rare of having any vegetation. This is due to the short period of time in which these terrains, up until recently, were ice covered, concentrating rookery activity in a few sites on the coast, consequently not promoting soil development.