Potential greenhouse gases emissions by different plant communities in maritime Antarctica.

Antarctic plant communities show a close relationship with soil types across the landscape, where vegetation cover changes, biological influence, and soil characteristics can affect the dynamic of greenhouse gases emissions. Thus, the objective of this study was to evaluate greenhouse gases emissions in lab conditions of ice-free areas along a topographic gradient (from sea level up to 300 meters). We selected 11 distinct vegetation compositions areas and assessed greenhouse gases production potentials through 20 days of laboratory incubations varying temperatures at -2, 4, 6, and 22 °C. High N2O production potential was associated with the Phanerogamic Community under the strong ornithogenic influence (phosphorus, nitrogen, and organic matter contents). Seven different areas acted as N2O sink at a temperature of -2 °C, demonstrating the impact of low-temperature conditions contributing to store N in soils. Moss Carpets had the highest CH4 emissions and low CO2 production potential. Fruticose Lichens had a CH4 sink effect and the highest values of CO2. The low rate of organic matter provided the CO2 sink effect on the bare soil (up to 6 °C). There is an overall trend of increasing greenhouse gases production potential with increasing temperature along a toposequence.

Apparent thermal diffusivity of soil in ice-free areas of Keller peninsula in maritime Antarctica.

Heat transfer process in the soil active layer is important for the knowledge of its thermal properties linked with climate issues. The objective of this work was to analyze the energy flux in different soil profiles by estimating the apparent soil thermal diffusivity ($ATD$). The study was carried out in Keller Peninsula, located at King George Island in four different sites differing by soil characteristics, as well as vegetation coverage and landscape setting. The $ATD$ was estimated in function of the long-term hourly temperature records at different soil depths. In addition, we estimated the seasonal mean of the $ATD$ and the freezing $N$-factor. Results showed that $ATD$ values were smaller at shallow depths and increased with depth. The diffusivity values presented lower variability in colder conditions, especially at deeper soil layers. Water content was the main factor affecting soil thermal diffusivity at sites $1$ and $3$ (more than $70$ and $63\%$ of probability). At sites $3$ and $4$ lower $N$-factors were observed, suggesting higher snow pack and permafrost closer to the soil surface. Hence, positive $ATD$ appears in the summer due to thawing increases soil moisture, while negative $ATD$ appears during the freeze of the snow pack and precipitation.

Changes in plant communities and soil attributes in the "Cousteau's whale bone skeleton" tourist attraction area in Keller Peninsula after 48 years.

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.

Evaluation of the agricultural potential of the serpentinite rock as a soil remineralizer.

Magnesium is one of the essential elements for the plant growth. However, when the supply of magnesium is required exclusively, few economically feasible options are available. Serpentinite represents an alternative source of magnesium, although little is known about its potential and efficiency under tropical soil conditions. This work aimed to evaluate the use of serpentinite as a soil remineralizer, as well as magnesium fertilizer. The study was conducted in a greenhouse, using a completely randomized design, with seven treatments and four replications, as follows: three levels of serpentinite, mix of serpentinite and phonolite, and the controls with dolomitic limestone and without fertilization. Two plant species (Zea mays L. corn hybrid BRS - 1055 and Phaseolus vulgaris L. common bean variety BRS - Estilo) and two contrasting soils (clayey and sandy texture), were used in pots. Results showed that serpentinite's free silica and toxic element contents fitted the legal requirements. No statistically significant difference was observed for the plant dry matter weight production in the serpentinite and dolomitic limestone control, as well as in the pure serpentinite and the mix with phonolite treatments. The serpentinite was able to supply and to fullfil magnesium requirements for growth and development of corn and bean plants.

High-resolution topography for Digital Terrain Model (DTM) in Keller Peninsula, Maritime Antarctica.

High resolution topography (HRT) surveys is an important tool to model landscapes, especially in zones subjected to strong environmental changes, such as Antarctica, where landform is highly influenced by cryoclasty and permafrost melting. The aim of this work was to obtain a high accurate DTM for Keller Peninsula, Maritime Antarctica. The survey study was assessed in the 2014/2015 and 2015/2016 during the austral summer, by using Terrestrial Laser Scanner (TLS). In order to cover 8 km² of the Peninsula, the TLS equipment was installed in 81 different points. Results of the DTM generated by TLS (hereafter, HRT-DTM), and the terrain variables Aspect, Slope and Hillshade obtained were compared with previous models generated by aerophotographic survey (hereafter, APG-DTM). RMSE for the HRT and APG-DTM were 0.726 and 2.397 m, respectively. Spatial resolution of the DTMs was 0.20 m. Morphometric variables obtained from the two methods presented visual differences on the thematic maps, especially related to the Aspect. Generalization was the main process, whereas interpolation occurred for the HRT survey, being the process of choice for the APG method. A large number of points are obtained by the TLS, providing a dense cloud of points, spatially well-distributed, enabling the generalization process to obtain surface models with high performance.

Indicadores participativos de qualidade do cafeeiro conilon e do solo em sistema agroflorestal e convencional / Participatory indicators of quality in conilon coffee and soil in agroforestry system and conventional

A avaliação participativa de agroecossistemas é uma técnica rápida e de fácil aplicação para avaliação da sustentabilidade de propriedades de agricultura familiar. Este trabalho teve por objetivo implementar e avaliar, em cinco propriedades rurais de Alegre (ES), uma metodologia prática e de fácil aplicação por agricultores na avaliação participativa de características indicadoras de qualidade do Coffea canephora e do solo. Foram avaliadas cinco áreas com sistemas de manejo convencional e conservacionista agroecológico de cultivo. A partir de observações feitas a campo notas foram atribuídas aos indicadores de qualidade do café e solo. As notas variam de 1 a 10 em 3 intervalos ( 0-5; 5-8 e 8-10). Gráficos em forma de radar foram elaborados, representando o estado de cada indicador, e comparados com as diferentes percepções dos produtores e técnicos da área agrícola. O diagrama da qualidade do café indicou no sistema convencional a alta dependência de insumos externos (nota 2) e grande efeito da radiação solar pela falta de cobertura vegetal na seca de ponteiros (nota 3). Já para a qualidade do solo no sistema conservacionista, notou-se controle da erosão (nota 9), maior profundidade da camada escura (nota 9) e maior diversidade de plantas (nota 9,5). Sistemas conservacionistas agroecológicos de cultivo promovem maior sustentabilidade da agricultura familiar e otimizam a produção agrícola.

Participatory evaluation of agroecosystems is a fast and easy application for assessing the sustainability of family farming properties. This study aimed to implement in five farms in Alegre (ES), a practical and easily applied by farmers in participatory evaluation of quality characteristics Coffea canephora and soil. Five sites were evaluated with conventional management system agroecological farming and conservation. From observations made in the field notes were assigned to the indicators of quality of coffee and soil. The scores range from 1 to 10 in 3 steps (0-5, 5-8 and 8-10). Graphics in the form of radar were plotted, representing the state of each indicator and being compared with the different perceptions of producers and technicians of the agricultural site. The diagram indicates the quality of coffee in the conventional high dependence on external inputs (note 2) and large effect of solar radiation by the lack of vegetation in dry hands (note 3). As for the soil quality in conservation system showed better erosion control (note 9), increased depth of the dark layer (note 9) and more diversity of plants (note 9.5). Agroecological farming systems conservationists promote greater sustainability of family farming and optimize agricultural production.