Abstract Areas of high concentration of seal carcasses have been observed in localized areas of James Ross Island, Antarctica. Such carcasses show an unusual vegetation development, in a semi-arid area with bare soils under intense winds, high salinity and sandy texture. We investigated carcasses of seals around a lake in James Ross Island, with four different stages of decomposition, with three replicates: Seal (S01), with recently mummified carcasses; S02, with partially degraded carcasses; S03, with broken carcasses with partially degraded exposed bones, and S04, with completely broken, scattered skeletons. The vegetation showed a maximum degree of development in carcasses at stages S02 and S03, with the environment between the skin and the skeleton as the preferred place for vegetation establishment. The chemical alteration was greater with increasing carcass decomposition but reduced with the spreading and final decomposition of the bones, with anomalous values observed only in the vicinity of the carcasses. It is concluded that the presence of carcasses of seals, concentrated in wet places, even in a semi-desert climate, represent important oases of nutrients, with a combination of physical and chemical effects throughout the decomposition process that favor plant establishment and succession.

Abstract Active layer and permafrost are important indicators of climate changes in periglacial areas of Antarctica, and the soil thermal regime of Maritime Antarctica is sensitive to the current warming trend. This research aimed to characterize the active layer thermal regime of a patterned ground located at an upper marine terrace in Half Moon Island, during 2015-2018. Temperature and moisture sensors were installed at different soil depths, combined with air temperature, collecting hourly data. Statistical analysis was applied to describe the soil thermal regime and estimate active layer thickness. The thermal regime of the studied soil was typical of periglacial environment, with high variability in temperature and water content in the summer, resulting in frequent freeze-thaw cycles. We detected dominant freezing conditions, whereas soil temperatures increased, and the period of high soil moisture content lasted longer over the years. Active layer thickness varied between the years, reaching a maximum depth in 2018. Permafrost degradation affects soil drainage and triggers erosion in the upper marine terrace, where permafrost occurrence is unlikely. Longer monitoring periods are necessary for a detailed understanding on how current climatic and geomorphic conditions affect the unstable permafrost of low-lying areas of Antarctica (marine terraces).

Abstract Maritime Antarctica is one of the major terrestrial ecosystems dominated by lichens and mosses, which represent important ecological indicators. Thus, we aimed to evaluate the changes in associated communities of mosses-lichens diversity and coverage along a pedoenvironmental gradient on Half Moon Island, Maritime Antarctica. We focused on how patterns in associated communities of mosses-lichens species diversity (richness, species composition and beta diversity) and coverage are associated with soil properties using plant inventory data from 174 plots across 14 contrasting pedoenvironments. The results clearly show marked differences in soil properties along the pedoenvironmental gradient, which determine variations in species composition, richness and coverage. We presumed that these variations are common in Maritime Antarctica owing to varying periglacial processes, weathering degree, parent material and biological influence (especially by penguins and other birds). The community species richness and coverage along the pedoenvironmental gradient differ, nevertheless share common species present in most pedoenvironments, despite differences in coverage. We assume that most of the pedoenvironments are habitats to rare species that occur only under specific soil conditions, additionally promotes high β-diversity between pedoenvironments and low species similarity.

Abstract Ice-free areas of Antarctica represent an important study region that helps us understand how human activity affects plant communities and soil properties. The goal of this study was to determine the changes in plant composition and soil properties around a whale bone skeleton (WB) near Ferraz Station, King George Island, Antarctica from 1972 to 2020 (48 years). The WB was assembled in 1972 by Jacques-Yves Cousteau and his team. It is located in a large moss field and visited by many tourists. We studied the plant composition and development based on historical and recent photographs and phytosociological studies from 1986 to 2020. The soil was sampled in February 2009 to determine general properties. The results showed that human activity surrounding the WB directly affected the plant community composition and soil properties. The Syntrichia cushions were positively affected by the calcium deposits from bone dissolution. The principal component analysis revealed that mineralization of the bones increased soil nutrient assembly. A strong phosphatization process was observed in the WB area, similar to that in ornithogenic soils. The WB on the marine terrace enhanced soil fertility and changed the plant community.

Abstract The Antarctic Peninsula has experienced some of the most accelerated warming worldwide, resulting in the retreat of glaciers and creation of new areas for plant development. Information regarding the plant dispersal processes to these new niches is scarce in Antarctica, despite birds being important vectors elsewhere. Many bird pellets (with feed remains such as bones and feathers) are generated annually in Antarctica, which are light and easily transported by the wind and include vegetation that is accidentally or purposely swallowed. The aim of this study was to analyze the presence of plant fragments within skua (Stercorarius/Catharacta spp.) pellets collected from two sampling areas in the Maritime Antarctic: Stinker Point (Elephant Island, 17 samples) and Byers Peninsula (Livingston Island, 60 samples), in the South Shetland Archipelago, during the austral summers of 2018 and 2020. In both study areas, five species of Bryophyta were found that were associated with the pellets and viable in germination tests in a humid chamber. The ingestion of Bryophyta for the skuas contribute to the dispersion of different moss species, including to areas recently exposed by the ice retreat. This is the first demonstration that skua pellets effectively act in the dispersion of Antarctic mosses.

Abstract The geomorphic dynamics on ice-free areas are crucial for understanding soil formation, vegetation and landscape stability in maritime Antarctic. We aimed to describe the soil formation on different landforms, following the Holocene glacial retreat at Stinker Point. Twenty profiles were sampled and classified, grouped into three landforms units: middle platforms and scarps, till/glacial deposits and present/Holocene raised beaches. Soil chemical and physical attributes were determined, and the vegetation type identified and quantified. Soils from till and glacial deposits can be separated by the age of exposure: older soils are stony, skeletic; and recently exposed till has soils with moderate depth, alkaline reaction and very high base saturation. Soils at the middle platforms are shallow, coarse-grained, skeletic, with abundant vegetation. Soils from the present-day beaches are alkaline, very coarse with no horizon differentiation, whereas soils on Holocene beaches are acid and nutrient-rich due to past or present-day influence of fauna. Soils from Stinker Point are generally shallow, skeletic and strongly related to the landforms and biogenic influences. Compared with other islands of the South Shetlands, in Elephant Island soil development is less pronounced, being this mainly attributed to the metamorphic nature of parent material, with greater resistance to weathering.

Abstract The aim of this research was to evaluate the physical attributes of Cambisol in apple (Malus domestica Borkh. cv. Gala) orchard under different weed management systems in the state of Santa Catarina (SC), Brazil. The treatments were as follows: control (no weed management), chemical desiccation and mowing. We took samples of undisturbed soil at depths of 0-5, 5-10, 10-15 and 15-20 cm. We evaluated hydraulic conductivity (HC); bulk density (BD); soil penetration resistance (Pr); total porosity (TP), macropores (MaP), micropores (MiP); soil aggregation indices such as arithmetic and geometric mean diameter of air-dried and water-stable aggregates (AMDad, AMDws, GMDad, GMDws, respectively); aggregate stability index (ASIAMD and ASIGMD) and volumetric water content (VWC). We also carried out principal component analysis (PCA) with the data. The mowing or desiccation treatments increased BD at the 15-20 cm depth compared to control. The mowing treatment had the highest ASIGMD while desiccation contributed to the lowest ASIGMD. The desiccation treatment decreased AMDws (0-10 cm), ASIAMD (0-5 cm) GMDws (5-10 cm) and reduced HC by 26% and 22%, respectively, compared to the mowing and control treatments. Through PCA we were able to separate the three treatments. The mowing treatment was correlated with HC, VWC at pressure of 600 kPa and ASIGMD; desiccation was correlated with BD and Pr; and control with ASIAMD, MaP and TP.

Resumo O objetivo do trabalho foi avaliar os atributos físicos de Cambissolo em pomar de macieira (Malus domestica Borkh. cv. Gala) em Santa Catarina, Brasil, submetido a diferentes manejos das plantas espontâneas. Os tratamentos avaliados foram: testemunha (sem manejo das espontâneas), dessecação química e roçada. Foram coletadas amostras indeformadas de solo nas profundidades de 0-5, 5-10, 10-15 e 15-20 cm, nas quais foram avaliadas a condutividade hidráulica (CH); densidade do solo (Ds); resistência do solo à penetração (Rp); porosidade total (PT), macroporos (MaP), microporos (MiP); índices de agregação do solo, sendo o diâmetro médio aritmético e geométrico dos agregados secos ao ar e estáveis em água (DMAsa, DMAea, DMGsa, DMGea, respectivamente); índice de estabilidade de agregados (IEADMA e IEADMG) e umidade volumétrica (UV). Também realizou-se uma análise de componentes principais (ACP) com os dados obtidos. O manejo com roçada ou dessecação aumentou a Ds (15-20 cm) quando comparado com a testemunha. O tratamento roçada foi responsável por apresentar o maior IEADMG, enquanto a dessecação contribui para o menor IEADMG. O manejo com a dessecação diminuiu o DMAea (0-10 cm), IEADMA (0-5 cm), DMGea (5-10 cm) e reduziu a CH em 26% e 22%, respectivamente, em relação à roçada e testemunha. Por meio da ACP foi possível separar os três tratamentos avaliados, sendo o manejo com a roçada correlacionado com a CH, UV na tensão de 600 kPa e IEADMG; a dessecagem correlacionado com DS e RP; e a testemunha correlacionada com IEADMA, MaP e PT.

ABSTRACT This study evaluated the physical attributes of Humic Cambisol cultivated with onion in a no-tillage system (NTSV) and conventional tillage system (CTS), as compared to a secondary forest. The treatments consisted of the use of cover crops, alone and intercropped in an agroecological onion NTSV for six years, in randomized blocks with five replications: spontaneous vegetation, 100% oats; 100% rye; 100% wild radish; intercropping of wild radish (14%) and rye (86%); and intercropping of wild radish (14%) and oats (86%). We also evaluated an onion cultivation area under CTS for ±38 years and a forest area (secondary forest for ±31 years). Undisturbed soil samples were collected at depths of 0-5, 05-10, 10-15 and 15-20 cm, and the soil density, total porosity, macro and micropores, mean geometric diameter and mean weighted diameter of aggregates, and volumetric moisture were evaluated. The NTSV increased the aggregation indices, total porosity and volumetric moisture in comparison to the CTS and the aggregation indices in relation to the forest area. Alone and intercropped wild radish with oats and rye improved the soil physical attributes as compared to the CTS.

RESUMO Este trabalho avaliou os atributos físicos do solo cultivado com cebola em sistemas plantio direto de hortaliças (SPDH) e preparo convencional (SPC) do solo, comparados à área de floresta secundária. Os tratamentos constituíram-se da utilização de plantas de cobertura, solteiras e consorciadas em SPDH agroecológico de cebola por seis anos, em blocos ao acaso com cinco repetições: vegetação espontânea, 100% aveia; 100% centeio; 100% nabo forrageiro; consórcio de nabo forrageiro (14%) + centeio (86%); consórcio de nabo forrageiro (14%) + aveia (86%). Adicionalmente, foram avaliadas duas áreas, uma sob SPC com cultivo de cebola por ±38 anos e outra de mata (floresta secundária, ±31 anos). Foram coletadas amostras indeformadas de solo nas profundidades de 0-5, 05-10, 10-15 e 15-20 cm, e nestas avaliaram-se a densidade do solo; porosidade total, macro e microporos; diâmetro médio ponderado e geométrico dos agregados, e umidade volumétrica. O SPDH aumentou os índices de agregação, a porosidade total e umidade volumétrica em comparação ao SPC, e equiparou-se aos índices de agregação em relação à área de mata. O nabo solteiro e consorciado com aveia e centeio melhorou os atributos físicos do solo em comparação com o SPC.

ResumoAs pesquisas definidas como estado da arte ou da questão, entre as várias nomenclaturas utilizadas, não constituem, aparentemente, uma preocupação efetiva entre os pesquisadores da Comunicação. A partir de um entendimento de que esta tarefa é não apenas necessária como também urgente, a pesquisa aqui relatada se debruça sobre a produção acadêmica stricto sensu desenvolvida nas duas últimas décadas dentro dos estudos de recepção. Foram analisadas as teses e dissertações produzidas nos Programas de Pós-Graduação em Comunicação no intervalo de 1990 a 2009 com vistas a mapear o cenário teórico metodológico adotado pelos pesquisadores que se dedicaram a compreender esse fenômeno complexo das relações entre “meios e audiências”. Os resultados apontam para um ainda lento crescimento desses estudos e vários desafios teóricos para o enfrentamento da problemática.

AbstractThe researches defined as state of the art or state of the question, among several names used, apparently do not constitute a real concern among researchers in Communication. Based on the understanding that this work is not only necessary, but also urgent, this research focuses on the stricto sensu academic production about reception studies developed in the past two decades. Thesis and dissertations produced in the Graduate Programs in Communication from 1990 to 2009 were analyzed, aiming to map the theoretical and methodological scenario adopted by researchers who made efforts to understand this complex phenomenon of relations between “Media and audiences”. The results point to a slow growth of these studies and several theoretical challenges as regards facing such theme.

ResumenLas pesquisas definidas como estado del arte o de la cuestión, entre las varias nomenclaturas utilizadas, no constituen aparentemente una preocupación efectiva entre los pesquisadores de la Comunicación. A partir de una comprensión de que esta tarea no es solo necesaria pero también urgente, la pesquisa aquí relatada se basa en la producción académica stricto sensu desarrollada en las últimas décadas dentro de los estudios de recepción. Fueron analisadas las tesis y disertaciones producidas en los programas de Post Grado en Comunicación entre 1990 y 2009 con el objetivo de hacer un mapa del escenario teórico-metodológico por los pesquisadores que se dedicaron a comprender ese fenómeno complejo de las relaciones entre “Medios y Audiencias”. Los resultados apuntan para un crecimiento todavía lento de estos estudios y varios desafíos teóricos para el enfrentamiento de la problemática.