Margéli Pereira de Albuquerque

In situ methane and nitrous oxide fluxes in soil from a transect in Hennequin Point, King George Island, Antarctic

The study aimed at to determine the magnitude of the methane (CH(4)) and nitrous oxide (N(2)O) flux rates in soils at Hennequin Point, King George Island, Antarctic, under different slope positions, vegetal covers and presence of skuas, as well as to evaluate the main soil and climate factors that are involved with the flux of such gases. In situ gas sampling (closed chamber method) was performed in four sites along a transect involving a skua nesting field in a moraine with 5% and 100% of surface covered by vegetal, and two poor-drained soils in the toeslope (a bare alluvium soil and a poor-drained moss field with 100% soil cover). Flux rates ranged from -0.86±0.45 to 2.75±1.52 μg N(2)O-N m(-2) h(-1) and -12.26±3.05 to 1.42±1.31 μg CH(4)-C m(-2) h(-1). The soil totally covered by vegetal in the skua field had the largest CH(4) influx rates. However, this benefic effect was counterbalanced by the greatest N(2)O efflux rates from this soil, resulting in the largest contribution to the global warming potential among the soils evaluated. Flux rates were closely related to soil temperature, but no significant relation was observed with mineral N contents and water-filled pore space. In turn, accumulated CH(4) and N(2)O emissions were closely related to the total N and total organic C stocks in the soil. Net CH(4) influx predominated even in the poor-drained soils, suggesting that the coarse soil texture avoided critical anaerobic conditions. No significant changes in flux rates were observed for sampling time along the day.

Comparative study of moss diversity in South Shetland Islands and in the Antarctic Peninsula

BackgroundThis paper presents a comparative study of moss diversity in three collection sites in the South Shetland Islands (King George, Elephant, and Nelson Islands) and one in the Antarctic Continent (Hope Bay, Antarctic Peninsula). In the King George, Elephant, and Nelson Islands, the collections were done in ice-free areas during the austral summers of years 1988, 1989, 1990, 1991, 1992, and 1994. In Hope Bay, the collections were done in the 2009 summer (February). All collections were deposited in the HCB (Chaves Batista Herbarium). FindingsThe King George Area is the most diverse area and the Hope Bay has the lowest diversity stats. The diversity stats for each region and the similarities between both are presented.ConclusionThis results suggested that harder climatic conditions determine lower diversity for the bryoflora.ResumenEn este trabajo se presenta un estudio comparativo de tres puntos de muestreo de musgosen las Islas Shetland del Sur (Isla Rey Jorge, Elefante y Nelson) y el Continente Antártico (Bahía Esperanza, Península Antártica). En las Islas King George, Elefante y Nelson, se tomaron muestras en las zonas libres de hielo durante los veranos australes de años 1988, 1989, 1990, 1991, 1992 y 1994. Hope Bay, las colecciones se hicieron en el verano austral de 2009 (febrero). Todas las colecciones fueron depositadas en el herbario de HCB (Herbario Chaves Batista). Los índices de diversidad para cada región se presentan, así como la similitud entre ellos.

Lichen-Moss associations in plant communities of the Southwest Admiralty Bay, King George Island, Antarctica

The phytosociology of plant communities in the Admiralty Bay ice-free areas (King George Island, South Shetland Islands, Antarctica) was investigated during the 2003/04 summer seasons. In this study associations among lichens and mosses were found, where the lichen species are dominant in the samples. A total of 10 associations are identified. For each association found in this work, descriptions are given and comments about their ecology and distribution in the study area are made. Key words: Antartic plants, phytosociology, ecology.

Description of plant communities on Half Moon Island, Antarctica

ABSTRACT During February–March of the austral summers of 2013/14 and 2014/2015, fieldwork was performed on Half Moon Island, South Shetland Archipelago, Antarctica, to evaluate the distribution and abundance of mosses and lichens, as well as to describe and map the plant communities there. The quadrat (20 × 20 cm) sampling method was employed in a phytosociological study that aimed to describe these communities. The area was mapped using an Astech Promark II® DGPS, yielding sub-metric precision after post-processing with software. The number of species totalled 38 bryophytes, 59 lichens, only one flowering plant (Deschampsia antarctica Desv.), and two macroscopic terrestrial algae. Five types of plant communities were identified on the island, as follows: (1) fruticose lichen and moss cushion, (2) moss carpet, (3) muscicolous lichen, (4) crustose lichen and (5) moss turf.

Methane and nitrous oxide fluxes in relation to vegetation covers and bird activity in ice-free soils of Rip Point, Nelson Island, Antarctica

This study aimed to quantify the nitrous oxide (N2O) and methane (CH4) fluxes at sites with different vegetation covers and where bird activity was present or absent using the static chamber method, on Rip Point, Nelson Island, maritime Antarctic. The sites were soils covered by Sanionia uncinata, lichens, Prasiola crispa, Deschampsia antarctica and bare soil. Seabirds used the P. crispa and D. antarctica sites as nesting areas. Soil mineral N contents, air and soil temperature and water-filled pore space were measured, and the content of total organic C and particulate organic C, total N, bulk density and texture were determined to identify controlling variables of the gas emissions. The N2O and CH4 flux rates were low for all sampling events. Mean N2O flux rates ranged from 0.11±1.93 up to 21.25±22.14 µg N2O m−2 h−1 for the soils under lichen and P. crispa cover, respectively. For the CH4 fluxes, only the P. crispa site showed a low positive mean (0.47±3.61 µg CH4 m−2 h−1). The bare soil showed the greatest absorption of CH4 (−11.92±5.7 µg CH4 m−2 h−1), probably favoured by the coarse soil texture. Bare soil and S. uncinata sites had N2O accumulated emissions close to zero. Net CH4 accumulated emission was observed only at the P. crispa site, which was correlated with (p<0.001). These results indicate that seabird activity influences N2O and CH4 soil fluxes, while vegetation has little influence, and bare soil areas in maritime Antarctica could be greenhouse gas sinks.

Gametophyte Length Variation Among Antarctic Populations of Polytrichum Juniperinum Hedw. (Polytrichaceae)

Up to now, no sporophytes of Polytrichum juniperinum were recorded in Antarctica. erefore, the long distance dispersal may be a rare event in this continent. In this study, we recorded the length of gametophytes sampled in natural populations from an Antarctic island, aiming to evaluate the presence of patterns of morphological di erentiation related to short distance dispersal of vegetative propagules. e mean size of gametophytes ranged from 2.85±0.59 cm to 7.01±1.34 cm, with signi cant overall di erentiation according to the analysis of variance. e populations’ pair-wise comparison was signi cant in 20 out of 21 pairs. In terms of clustering of morphologically similar populations due to short distance dispersal, the degree of morphological di erentiation between sample locations slightly increased with geographical distance, although not statistically signi cant. Considering the absence of signi cant correlation between gametophyte size and geographic distance observed for the populations studied, adaptation to micro-environment seems to be the best explanation for the observed di erentiation. Further morphological records and studies based on molecular genetic markers are being developed by our group, in order to determine if such di erences have also some genetic basis.

Soil Chemical Attributes as Affected by Vegetal Cover and Seabirds in Punta Hennequin, Antarctica

is study had the purpose of evaluating the e ect of soil cover by vegetation on soil chemical attributes in a skua (Catharacta maccormicki) eld at Punta Hennequin, Shetland Island, Antarctica. Four locals along a transect were sampled, involving soils with 5 and 100% of vegetal cover (L1 and L2, respectively) with Deschampsia+Colobanthus; bare alluvium soil (L3); and poor-drained moss (Sanionia uncinata) carpet with 100% soil cover (L4). Soil samples obtained from three layers and three replicates were submitted to chemical and physical analysis. Although both L1 and L2 are in the same nesting eld, the more abundant vegetation at L2 promoted signi cantly larger (P < 0.05) total organic C (TOC) stocks in the soil than at L1 (43.08 and 9.03 Mg C ha–1, respectively, at the 0-40 cm layer). Total N stocks increased from 2.60 to 6.54 Mg ha–1 for L1 and L2, respectively. Although the presence of seabirds represents an important transfer of organic material from marine to the terrestrial environment, the di erences evidence the importance of vegetation in order to raise the soil organic matter levels. Soil pH was consistently lower in L2 than L1 about 1.0 unit for the soil layers herein evaluated, which is probably linked to the soil organic matter accumulation. Contrary to the distribution of TOC and TN contents, exchangeable P and K had no gradient along the soil pro le, evidencing that most of the P and K is native from the parent material and their input by seabirds to the soil is negligible.

Conservation Status of Moss Species in Northern Maritime Antarctic Based on the Index of Ecological Significance

e aim of this work was to verify moss conservation status on ice-free areas of northern Maritime Antarctic, including data of Elephant Island, King George Island and Deception Island. e study started with the classi cation and description of the plant communities based primarily on phytosociological and biodiversity data. All records were obtained from 1991-1992 to 2003-2004 austral summers. e coverage degree and frequency of each species found was used to calculate the index of ecological signi cance. 22 most frequent species based on all island records were found. e most important species in both studied areas were Sanionia uncinata (Hedw.) Loeske, Polytrichastrum alpinum (Hedw.) G. L. Smith, Bartramia patens Brid., respectively, occurring in all the studied islands. ese results demonstrate the fragility of plant communities in Maritime Antarctic, based on the low frequency and coverage of most species known to this area. Keyword: Bryophyta, ice-free areas, plant communities http://dx.doi.org/10.4322/apa.2014.063

Lichen Moss Association Frequently Found in Maritime Antarctic

e aim of this work was to report on the lichen-moss association in the ice-free areas of Elephant Island, King George Island, Nelson Island and Deception Island. e study started with the classi cation and description of the plant communities based primarily on phytosociological and biodiversity data. All data were obtained from 2003-2004 to 2011-2012 austral summers. 12 most frequent lichen-moss association species based on all island records were found. e most frequent association in both studied areas involved foliose-crustose lichen with a moss carpet species, such as Psoroma cinnamomeum Malme with Sanionia uncinata (Hedw.) Loesk. e occurrences for each island as well as the common association found in all sampled islands are demonstrated.

Mapping and Geopositioning Methods in Ice-Free Areas Antarctica

Mapping is an activity which can register the occurrence of phenomenons related to land cover. ere are several methods of map registry. In Antarctic areas, the mapping gives importance to registry of the land cover of plants in ice-free areas. e maps are tools to understand the dynamics of plants in those areas. e Global Navigation Satellite System (GNSS) is an important tool to reach this objective, such as the plotting of georeference points in any place in the world including Antarctic locations. is study aims to contribute to the research of mapping in ice-free areas making a comparison with map builds for Hennequin Point and Keller Peninsula at King George Island, Antarctica. e study was carried out using GNSS L1/L2 and L1 receivers to record points in ice-free areas with plant coverage and post processing using speci c so ware. e post processed data were exported to CAD so ware. With the points plotted, they were connected using polylines to draw the vegetation patches. e maps obtained were overlapped to identify the growth or retraction between the patches. e resulting maps are presented. e results show di erences between the patches sampled during di erent polar years. Probably, these divergences are due to the di erent methodologies used to obtain the points in these areas. To better understand these variations, we need to produce more maps of the same place, obtained with the same methodologies or compare them using Satellite Images with high spatial resolution.