Felipe Nogueira Bello Simas

Soils associated with rock outcrops in the Brazilian mountain ranges Mantiqueira and Espinhaço

A Serra do Espinhaco e a Serra da Mantiqueira sao duas cadeias de grande importância para o Brasil. Nas partes mais altas destas serras encontramse ecossistemas com caracteristicas singulares, associados aos afloramentos rochosos, denominados Complexos Rupestres de Altitude. Esses ambientes apresentam caracteristicas do solo e da vegetacao distintas das areas adjacentes. Os solos sao em geral rasos, arenosos, com alta saturacao de aluminio e teores variados de materia orgânica. Neossolos Litolicos, Cambissolos e Organossolos sao as classes de solo dominantes, diretamente associadas aos afloramentos, formando um mosaico de solos. Alguns solos encontrados nestes ambientes sao endemicos, em funcao das caracteristicas peculiares da rocha matriz, da topografia e da vegetacao, e sua preservacao e estrategica por se tratar de solos raros e ameacados de extincao. A materia orgânica desses solos apresenta alto grau de humificacao, com grande quantidade de fracoes soluveis, e a presenca generalizada de fragmentos de carvao. Horizontes espodicos e rios negros estao tipicamente associados as areas de afloramento de arenito e quartzito, sendo formados pela iluviacao de compostos orgânicos, e sendo menos comuns nas areas de granito. O oligotrofismo destes solos, associado a outras limitacoes de ordem quimica e fisica, induzem o desenvolvimento de estrategias de adaptacao fisiologica e morfologica por parte da vegetacao. A maioria destes ecossistemas e instavel sob a condicao climatica atual, e a intervencao antropica e um fator de aceleracao do processo de degradacao. A descricao detalhada dos solos nestes ambientes e fundamental para um melhor entendimento do seu papel nos processos ecologicos e para o desenvolvimento de politicas de conservacao.

CLAY-SIZED MINERALS IN PERMAFROST-AFFECTED SOILS (CRYOSOLS) FROM KING GEORGE ISLAND, ANTARCTICA

Cryosols from Maritime Antarctica have been less studied than soils from continental areas of Antarctica. In this work X-ray diffraction, difference X-ray diffraction, differential thermal analysis, thermogravimetry, transmission electron microscopy/energy dispersive spectroscopy and selective chemical dissolution were used to characterize the clay fraction of basaltic, acid sulfate and ornithogenic Cryosols from ice-free areas of Admiralty Bay, King George Island. Non-crystalline phases are important soil components and reach >75% of the clay fraction for some ornithogenic soils. Randomly interstratified smectite-hydroxy-Al-interlayered smectite is the main clay mineral of basaltic soils. Kaolinite, chlorite and regularly interstratified illite-smectite predominate in acid sulfate soils. Jarosite is also an important component of the clay fraction in these soils. Crystalline Al and Fe phosphates occur in the clay at sites directly affected by penguin activity and the chemical characteristics of these ornithogenic sites are controlled by highly reactive, non-crystalline Al, Si, Fe and P phases. Chemical weathering is an active process in Cryosols in Maritime Antarctica and is enhanced by the presence of sulfides for some parent materials, and faunal activity.

Spatial variability models of CO2 emissions from soils colonized by grass (Deschampsia antarctica) and moss (Sanionia uncinata) in Admiralty Bay, King George Island

Abstract Soil CO2 emission is an important part of the terrestrial carbon cycling and is influenced by several factors, such as type and distribution of vegetation. In this work we evaluated the spatial variability of soil CO2 emission in terrestrial ecosystems of maritime Antarctica, under two contrasting vegetation covers: 1) grass areas of Deschampsia antarctica Desv., and 2) moss carpets of Sanionia uncinata (Hedw.) Loeske. Highest mean emission was obtained for the Deschampsia (4.13 μmol m-2 s-1) developed on organic-rich soil with a strong penguin influence. The overall results indicate that soil temperature is not directly related to the spatial pattern of soil CO2 emission at the sites studied. Emission adjusted models were Gaussian and exponential with ranges varying from 1.3 to 2.8 m, depending on the studied site and vegetation cover.

Characterization and mapping of plant communities at Hennequin Point, King George Island, Antarctica

King George Island is the largest island and the principal area used for research bases in Antarctica. Argentina, Brazil, Chile, China, Poland, Russia, South Korea and Uruguay have permanent open bases on this island. Other countries have seasonal summer stations on different parts of this island, which demonstrates that human impact is strong on King George Island relative to other areas in the maritime and continental Antarctica. The objective of this work was to present a phytosociological approach for ice-free areas of Hennequin Point, eastern coast of Admiralty Bay, King George Island. The study started with the classification and description of the plant communities based primarily on phytosociological and biodiversity data. The area was mapped using an Astech Promark II® DGPS, yielding sub-metric precision after post-processing with software. The plant communities were described as follows: (1) lichen and moss cushion formation; (2) moss carpet formation; (3) fellfield formation; (4) grass and cushion chamaephyte formation; and (5) Deschampsia Antarctica–lichen formation. Characterizations and distributions of the plant communities are presented on a map at a scale of 1:5000. The plant communities found at Hennequin Point, in general, differ from those found in other areas of the Admiralty Bay region, probably because of the concentration of skua nests in the area and the relief singularities. We conclude by highlighting the importance of the study of plant species found in the ice-free areas of the Antarctic with respect to environmental monitoring and for evaluating global climate and environmental changes.

Soils of the South Orkney and South Shetland Islands, Antarctica

The present Chapter presents an overview on soils from Maritime Antarctica, comprising ice-free areas distributed along the South Orkney (SOI) and South Shetland Islands (SSI). Published and novel data were compiled, with focus on pedogenesis and soils geography, in a total of 365 pedons, of which 71 % are from King George Island. Seven soil-forming processes occur, including cryoturbation, gleization, melanization, podzolization, paludization, and phosphatization. Six soil orders have been reported in the SOI and SSI, including Gelisols, Entisols, Inceptisols, Histosols, Mollisols, and Spodosols, which represent half of the orders in ST. Gelisols are predominant at altitudes above 30 m.a.s.l. to 100 m.a.s.l., where discontinuous permafrost exists. The most abundant great group is the Haploturbels, illustrating the importance of cryoturbation. We conclude with a summary of the current knowledge on soil formation and distribution in the SOI and SSI, and a prospect of future research needs and questions.

Windows on Antarctic soil–landscape relationships: comparison across selected regions of Antarctica

Abstract This paper brings together topographic cross-section ‘windows’ from across Antarctica to illustrate soil–landscapes from the margins of the polar plateau in the Transantarctic Mountains and McMurdo Dry Valleys, through East Antarctic coastal areas, to the northern Antarctic Peninsula Region. Soils identified range from Gelisols in the Ross Sea Region, through Gelisols and Entisols in coastal East Antarctica, to a mixture of Gelisols, Entisols, Spodosols and Inceptisols in the northern Antarctic Peninsula Region where permafrost is not ubiquitous. The relative impacts of the soil-forming factors are considered. At a continental scale climate is the main driver of the differences observed between soils in different areas. At local scales strong soil–topographic relationships are observed. Organisms, time and parent material are dominant influences on soil properties only in relatively localized situations. Organisms dominate in areas of organic matter or guano accumulation and time is a dominant influence on exceptionally old upland surfaces in the McMurdo Dry Valleys. The US Department of Agriculture’s Soil Taxonomy gives a useful overall appraisal of Antarctic soils; however, for detailed work, there is a need to introduce some new categories at subgroup level to better capture the range of soils described.

Hg distribution and speciation in Antarctic soils of the Fildes and Ardley peninsulas, King George Island

Abstract Data on the content and speciation of mercury (Hg) in the soils of Antarctica are scarce and vary greatly between the regions studied, but overall Hg concentrations found were generally very low. We investigated the Hg quantity and speciation by solid-phase Hg pyrolysis and chemical fractionation in selected maritime Antarctic soils, comparing ornithogenic and non-ornithogenic areas of the Fildes and Ardley peninsulas of King George Island. The total Hg contents ranged from 4.3–256 ng g-1, and values for ornithogenic soils were the highest recorded for Antarctic soils. A close correlation between Hg and organic matter was observed in the ornithogenic soils, with levels decreasing with depth. In the non-ornithogenic soils, a correlation between Hg content and soil depth was also observed, but the values were found to increase with depth. Thermograms showed that all Hg was in the 2+ oxidation state and was predominantly linked to organic matter, corroborating the chemical fractionation results for the ornithogenic soils. These results show the need for further refined studies about the interactions of Hg with organic matter in order to better understand the biogeochemistry of this metal in the Antarctic environment.

Methods for evaluation of easily-reducible iron and manganese in paddy soils

ABSTRACT Iron (Fe) and manganese (Mn) toxicity can be an important limitation to flooded rice cropping. Flooding causes several physical and chemical alterations that affect the dynamics of these elements in the soil environment. The objective of this study was to develop procedures of soil analysis, that enable the assessment of easily reducible Fe and Mn availability and uptake by plants. Surface samples (0–20 cm) of ten lowland soils from the State of Minas Gerais, Brazil, were used. The experiment consisted of a factorial randomized block design of ten soils and five liming levels, with five rice plants grown in pots containing 2 dm3 of soil with permanent flooding. The concentrations of Fe and Mn were evaluated in the soil solution and in the aerial parts of the rice plants. The air-dried samples were analyzed for Fe and Mn with sodium-citrate dithionite, ammonium oxalate, Melich-1, 0.1 mol L−1 HCl, ammonium acetate–EDTA, and DTPA–TEA extractants. The Fe concentration in the soil solution was most highly correlated with Melich-1 (r = 0.87), while DTPA–TEA showed the highest correlation with the amount of Fe in the plant (r = 0.62). For Mn, DTPA–TEA was the best predictor of both soil solution Mn and plant Mn (r = 0.87 and r = 0.80, respectively).

Caracterização de geoambientes da floresta nacional do purus, Amazônia ocidental: uma contribuição ao plano de manejo

The lack of basic studies for the elaboration of management plans has delayed the effective implementation of conservation units in the Amazon region. In this work, the interpretation of orbital and sub-orbital images, together with field surveys were used for the geoenvironmental characterization of the Purus National Forest (PNF). A georreferenced digital database composed of thematic maps was produced and constitutes the base of a GIS for the PNF. Four geoenvironments were identified and mapped: Dissecated Plateaux with forest vegetation on Latosols and Argisols; Forested slopes on Argisols; Alluvial plains with eutric soils; Alluvial plains with dystric soils. The holocenic alluviums influenced by the Purus River are eutric, and receive sub-Andenean sediments. On the other hand, most of the PNF has extremely poor and acid soils related to the Solimoes Formation. Since the nutrient levels in the mineral substrate are very low, the management of these areas should seek the increment of biomass in the system, which would enhance nutrient cycling by the vegetation since the nutrient levels in the mineral substrate are very low.

Fosfatização de solos e evolução da paisagem no arquipélago de Abrolhos, BA

The activity of the avifauna on terrestrial ecosystems results in the intense chemical and mineralogical alteration of mineral substrates. The objective of the present work is to investigate the impact of the avifauna on landscape evolution at the Abrolhos Archipelago, based on soils chemical characteristics and spatial distribution. A total of 10 soil profiles are described and analyzed, representing the main landscape units present in the Archipelago. Based on careful field observation and interpretation made on the existing nautical map (n.1311), produced by the Brazilian Navy (scale 1:100.000), detailed soil maps were produced. The widespread occurrence of strongly ornithogenic soils in areas without current nesting activity indicates a much broader occupation by birds in the past. Some of the studied soils are of difficult classification, and reflect the marked influence of present-day and past avifauna activity.