Abstract Understanding the influence of fine-scale abiotic filters on plant communities can provide important insights into floristic patterns of the Brazilian Cerrado. We aimed to evaluate the interactions of the soil and the plant community composition with their distribution in different sandy environments of Brazilian Cerrado, the Jalapão region. Eight environments were sampled, each with ten plots of 20 × 50 m. All woody individuals presenting circumference at soil height ≥ 10 cm were sampled. Subplots of 5 × 15 m were demarcated, where woody individuals with a circumference at soil height ≥ 5 and < 10 cm were sampled. Subplots of 2 × 2 m were also demarcated to sample herbaceous individuals. Soil samples varying from 0 to 20 cm of depth were collected for each plot (20 × 50 m). Overall, 20000 individuals that belong to 338 species and 76 families were sampled. The dominant family was Fabaceae. There were significant differences among the environments regarding species richness and soil. The analyzed soils are extremely poor and with a tendency to sandy texture, small chemical and/or physical variations imply differences in the distribution of vegetation. Our study revealed abiotic filters exerted crucial fine-scale effects on plant community in the Jalapão region.

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 This work aimed to characterize the variation in the thermal regime of the active layer in a permafrost area on Fildes Peninsula, Antarctica, and relate this variability with meteorological data between 2014 and 2016. The monitoring site was installed to continuously monitor the temperature and moisture of the active layer, radiation flow on the surface, and air temperature. We used data collected to generate the indexes freezing degree-days, thawing degree-days, frost number, n-factor, apparent thermal diffusivity, and active layer thickness. The temperature of the active layer is not homogeneous, varying with depth and position in the transect, with the greatest variations in soil with better drainage and lower moisture content. Among the evaluated factors, air and soil surface temperature are the ones that most influence the thermal gradient of the active layer. We identified that near the surface there is a greater influence of albedo and cloudiness and at -35 cm depth there is a greater influence of net radiation and soil moisture. The average depth of the active layer in 2014 was -44.3 cm and in 2015 -47.7 cm and the frost number index indicates that there was a predominance of continuous permafrost in the transect during the monitoring.

Abstract Understanding the influence of soil-forming factors and processes in ornithogenic soils is important to predict impacts of climate change on Antarctic ecosystems. Herein, we analyzed the soil-landscape interplays and development of ornithogenic soils at Harmony Point (HP), Nelson Island. We collected, described, and classified 24 soil profiles, combined with vegetation and landforms descriptions. Geoprocessing techniques were employed for mapping. Soil physical, chemical, geochemical, and mineralogical analyses were applied. Patterned ground, “Ornithogenic”/Typic Gelorthent, and moss carpets were the dominant landform, soil and vegetation classes, respectively. Soils from rocky outcrops were more structured, acidic, with higher organic carbon, organometallic complexes, and secondary phosphate minerals, due to former bird influence. Soils from cryoplanated platforms presented higher water pH, base saturation, clay content, and secondary silicate minerals. Soils from marine terraces presented high exchangeable bases, phosphorous, and amorphous phosphate minerals. Soil chemical weathering is enhanced by ornithogenesis and widespread in HP. Besides ornithogenesis, organic matter accumulation, cryoturbation, and cryoclastic processes are also important to pedogenesis of ornithogenic soils. The soils of the cryoplanated platforms exhibited a gradient of pedogenetic development corresponding to increasing biota influence and distance from glacier. In contrast, soils of rocky outcrops were more developed even close to the glacier, due to ornithogenesis.

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 Microplastics are ubiquitous contaminants of marine ecosystems around the world and Antarctica is no exception. Microplastics can be influenced by sedimentary dynamics mainly on coastal areas where they are more abundant in Antarctica. This study evaluated microplastic contamination in beach environments from two Antarctic Specially Protected Areas, aiming to identify relationships between microplastic numbers and sedimentological parameters on beach sediments. Low numbers of microplastics were found (> 0.5 mm; fibers excluded) – one particle per sample in 4 of 15 samples analyzed – and there is no evidence of widespread contamination. Sedimentological parameters reveal differences between sampled environments, but low numbers of microplastics impaired statistical comparison. All sediment samples are coarse, denoting highenergy depositional environments that are likely little susceptible to microplastic accumulation. Microplastic contamination in the Antarctic coastal ecosystem is heterogeneous, and their detailed characterization assisted by a systematization of methods can improve the understanding of microplastics distribution patterns in the cold coastal ecosystem.

Abstract The Serra do Divisor National Park (SDNP) in the Westernmost Brazilian Amazonia possesses unique Mountain landscapes of sub-andean nature, with high geo-biodiversity and pristine environments, with a potential high contribution in ecosystems services. We studied and mapped the basic geo-environmental units of the main sector of the Park, evaluating soil carbon stocks as a key ecosystem service provided by the Protected Area. For the identification, characterization and mapping of the geoenvironmental units, we integrated pedological, geomorphological and vegetation data obtained by local soil survey and field campaigns, as well as secondary data. Eight geoenvironmental units were identified and mapped, distributed in three main compartments: the Serra do Divisor (SD) the upper Moa River and the medium Moa River. This region presents similar environments to the sub-Andean region, notably the Ceja Forest at the top surface of the SD. Soils at the SD have high organic carbon accumulation, with close association with the nutrient-poor, quartz-rich rocks, and shows organic matter illuviation indicating active podzolization. The SDNP encompasses important ecosystems and services linked with high geo-biodiversity, and high soil carbon stocks, representing a new frontier for scientific research in the only area of transitional sub-andean forested landscape in Brazil. (SDNP subandean sub andean nature geobiodiversity geo biodiversity environmental Area identification pedological campaigns compartments (SD subAndean Andean accumulation nutrientpoor, nutrientpoor nutrient poor, poor nutrient-poor quartzrich quartz rich rocks podzolization geobiodiversity, biodiversity, Brazil

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 Benthic cyanobacterial assemblages from ponds distributed along inland-coastal gradients in the McMurdo Sound region were studied during the 2011/12 Antarctic summer season. Twenty-five ponds were sampled in four distinct geographic locations, including the Lower and Upper Wright Valleys, Ross Island and the McMurdo Ice Shelf. For morphological identification, benthic mat samples were thawed and a subsample was directly observed by light microscopy. Remaining sample material was stored in 50 ml sterile polycarbonate bottles containing the mineral nutrient medium MLA for future studies, maintained at a temperature of 21°C. Ten morphological criteria were used to describe the morphotypes (trichome shape, number of trichomes in sheath, presence or absence of terminal attenuation of trichome, calyptra on mature apical cell, shape of apical cell, presence or absence of constrictions at transverse walls, granules, branching, range in width of trichomes and range of cell length) with reference to available identification literature. All morphospecies were documented using photomicrography. In total, 29 morphospecies were described, four assigned to the order Chroococcales, three to Nostocales and 22 to Oscillatoriales. The four geographic locations had similar taxonomic richness, sharing many morphospecies. However, each also contained distinct floristic elements that were rare or absent from the others.

Abstract This study characterized the physical, chemical, macro- and micromorphological soil properties from three successive marine terrace levels from Harmony Point (Nelson Island, Maritime Antarctica) in order to understand the pedological signatures of Quaternary coastal landscape evolution of Maritime Antarctica. Soils were sampled on the Late Holocene beach (current beach) and Mid Holocene marine terraces higher up, at 3, 8, and 12 m a.s.l. At the lower levels, the predominant soils were Gelorthents, whereas Haplogelepts dominate the higher terraces. Soil properties are mostly influenced by parent material and faunal activity, in which cryoclastic (thermal weathering) and phosphatization are the main soil-forming processes. Soils from the upper levels are more developed, deeper with reddish colors, granular structures and incipient formation B horizon. These horizonation features highlight that soils vary according with age of glacier-isostatic terrace uplift, representing a Quaternary soil chronosequence. All marine terrace levels are Ornithogenic soils, at varying degrees. However, the presence of old bird nesting sites for long periods led to formation of phosphatic horizons, stable Fe-phosphate minerals and abundant vegetation in the highest terraces of this part of Maritime Antarctica.

Abstract The behavior and feeding habits of different species of seabirds can influence the enrichment of trace metals in Antarctic soils. This study aimed to evaluate the influence of different species of seabirds on the concentrations of potentially toxic metals in Antarctic soils. For this, we collected soil samples in areas influenced by penguins, kelp gulls, and giant petrels. We analyzed the concentration of total organic carbon (TOC), total nitrogen (TN), available phosphorus (P) and metals by three different methods of extraction: USEPA 3051A, Mehlich-1, and distilled water. The concentrations of Cr and Hg presented positive correlations with P, TOC, and TN by the USEPA 3051A method, indicating the biotransport of these metals by seabirds. Soils influenced by penguins showed higher levels of P, TOC, TN, Cr, and Hg. Comparing the results from the different extractors, we found that Hg had the highest relative levels in the exchangeable fraction and the soil solution. Therefore, the soils with the influence of penguins present higher levels of biotransported trace metals, but this does not necessarily mean that these birds have a higher biotransport potential, since the concentration of trace metals in these soils may be related to their degree of ornithogenesis.

Abstract Sulfurization is a pedogenic process that involves pyrite oxidation and strong soil acidification, accounting for the formation of acid sulfate soils. In Antarctica, acid sulfate soils are related to specific parent materials, such as sulfide-bearing andesites in Maritime Antarctica and pyritized sedimentary rocks in James Ross Archipelago. The hypothesis is that the acid sulfate soils of these regions vary according with a climate gradient. The reviewing of current data showed that the acid sulfate soils of warmer and wetter Maritime Antarctica have a greater weathering degree, higher acidity, leaching, phosphorus adsorption capacity, structural development, and well-crystallized iron oxides and kaolinite formation. On the other hand, the sulfurization at the drier region of James Ross Archipelago is counterbalanced by the semiaridity, resulting in lower acidity and higher base contents combined with little morphological and mineralogical evolution besides presence of weatherable minerals in the clay fraction. The sulfurization process interplays with other pedogenic processes, such as the phosphatization in Maritime Antarctica and salinization in James Ross Archipelago. Higher temperatures and soil moisture enhance the pedogenesis, showing that even the Antarctic sulfate soils, which originated from specific parent materials, have their development and characteristics controlled by a clear climatic gradient.

Abstract The majority of ornithogenic soils studied in Antarctica focus on the influence of penguins, wherever little reports evaluated the influence of flying birds on soil genesis. This study aimed to characterize the morphologic, chemic, physic, mineralogic, and micromorphologic ornithogenic soil pockets influenced by flying birds in Snow Island, Maritime Antarctica. Fifteen soil pockets were selected, described, sampled and analyzed, these sites constitute the main areas with intense long-term terrestrial biological activity in Snow Island. In order to investigate the impact of phosphatization, we compared the soil pockets with the surrounding soils and soils affected by penguins. Zone of phosphatization have a high concentration of P, K, and Ca. The XRD patterns for the clay fraction of ornithogenic soils show that phosphate minerals are the main crystalline phases (leucophosphite, minyulite, fluorapatite, and apatite). We show that even under typical periglacial conditions, sites influenced by flying birds present active chemical weathering processes. The phosphatization release exchangeable bases and accelerate mineralogical and micromorphological transformations in soils. Under the current global warming trend and expected sea-level rise, the ornithogenic environments are susceptible to accelerated erosion rates and a great part of these hotspots may be lost for the open sea.

Abstract Southern giant petrels (Macronectes giganteus) are found in the Antarctic. They build their nests with rock fragments, disturbing large areas during incubation and chick feeding periods; however, their impact on vegetation is unknown. Thus, we aimed to evaluate the effect of Petrel nests and associated breeding activities on the diversity and structure of cryptogam communities of Stinker Point, Elephant Island. We selected 13 nests in February and March 2012 and continue the monitoring in 2018. The area of direct influence of breeding activities was photographed to calculate plant community coverage. The results demonstrated that species richness, community coverage and composition, and beta diversity showed significant differences between active and inactive nests. The linear mixed-effect models revealed that the positive effect of nest area mainly caused variation in community coverage, but had a negative effect on beta diversity. Sphaerophorus globosus (lichen) grew around the inactive nests, sometimes forming a ring up to 1 m in diameter. This ring was then surrounded by the Chorisodontium acyphyllum moss colonized by S. globosus, and a final ring of Sanionia uncinata, colonized by the same lichen. Recently constructed nests are generally surrounded by Prasiola crispa and Sanionia uncinata carpets.

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.