•Secondary phosphates controlled by microstructural and microchemical factors.•The degree of rock fracturing influences the infiltration of guano at depth.•The degree of serpentinization controls the ...microchemistry of phosphate.•Sedimentary rock’s minerals are linked to Holocene sea-level cycles and SPSPA uplift.
The São Pedro and São Paulo archipelago (SPSPA) is noteworthy for its unusual lithology when compared to other oceanic archipelagos, consisting of mylonitized and serpentinized peridotites, and rare carbonate sedimentary rocks. There, marine bird species use these substrates as a nesting ground and excrement deposition (i.e. guano), resulting in widespread phosphatization of local substrates. The unique geological nature of the SPSPA makes it particularly fascinating for geochemical and mineralogical research since diverse lithological, microstructural and microchemical attributes are present. This study aims to investigate the microscale chemical and mineral composition of the phosphatization materials in SPSPA, in relation to different geological substrates and associated mineralogy. Speleothems of secondary phosphates formed in fractures and on the walls, as a result of guano percolation. The microstructural control is the primary factor, which depends on the degree of rock fracturing. Wider and interconnected fractures allow the gravitational flow of cations and phosphate rich solutions with resulting phosphatization. Secondary factor is the substrate/guano interaction, which contributes to the precipitation of secondary phosphate minerals. The microchemical control is influenced by the degree of serpentinization, which leads to the generation of iron phosphates with structural potassium and aluminum. Phosphatization of sedimentary rocks is associated with pre-existing fractures and cavities, as well as the carbonate composition of the rock. This study enhances our understanding of varying ornithogenesis in the SPSPA, with a specific emphasis on the process of phosphatization of oceanic islands. Understanding this process can assist in understand the genesis of phosphate deposits in comparable environments, enhancing the knowledge of the biogeochemical cycle of phosphorus on Earth.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Antarctica is mainly dominated mainly by non-vascular species.•The pedoenvironmental gradient shapes non-vascular species assemblages.•Soil texture affects species composition but not ...richness.•Fine-scale pedoenvironmental heterogeneity promotes beta diversity.
The main terrestrial ecosystems dominated by lichens and mosses, which represent important ecological indicators of climatic changes in high polar latitudes, are found in the Antarctic continent. However, little is known about how environmental filtering shapes cryptogamic communities’ assemblages at fine-scale. In this study, we analysed changes in non-vascular species richness, species composition and plant coverage along a pedoenvironmental gradient in Maritime Antarctica. We hypothesized that pedoenvironmental filters (i.e. soil texture and chemistry properties) drive the non-vascular assembly community. We classified soils according to the World Reference Base for Soil Resources, selecting ten different pedoenvironments at fine-scale. The plant inventory data from 206 plots across these pedoenvironments was used to evaluate the main effect of plant coverage, soil texture and soil chemistry on non-vascular species richness and composition. The ecological value of the species was determined and the type of community it occurred in was characterized, then the associations of the species were classified in each pedoenvironment. Differences in species richness, species composition and plant coverage were detected along the pedoenvironmental gradient. However, plant coverage, soil chemistry, soil texture and soil variables did not affect species richness and species composition, with the exception of clay content that was particularly an important predictor of species composition. High pedoenvironmental filtering apparently has no effect on species richness but determined differences in species composition. Therefore, we assumed that pedoenvironmental filtering determined high beta diversity in this island from maritime Antarctica. This study reveals that fine scale heterogeneity contributes to specific species associations along a pedoenvironmental gradient; thus, pedoenvironmental filtering not only determines diversity pattern in non-vascular plants, but also type of communities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Understanding how environmental drivers induce changes in plant composition and diversity across evolutionary time can provide important insights into community assembly mechanisms. We evaluated how ...taxonomic and phylogenetic diversity and structure of plant communities change along a local-scale edaphic and elevational gradient in the Tepequém table mountain, Brazilian Amazon. We selected three phytophysiognomies along the altitudinal gradient: Open Rupestrian Grassland, Shrubby Rupestrian Grassland, and Forest. We compared community composition and taxonomic and phylogenetic diversity between phytophysiognomies, and analysed effects of altitude and soil properties on species richness and phylogenetic metrics using linear mixed-effects models. The highest species richness and phylogenetic diversity were found at a lower elevation for Forest. All standardised phylogenetic metrics were significantly lower in Shrubby Rupestrian Grassland. This phytophysiognomy showed phylogenetic clustering. Forest showed a cluster pattern when only terminal nodes are considered and random dispersion to deep phylogenetic nodes. Open Rupestrian Grassland also showed a random phylogenetic structure. The linear mixed-effects models showed that species richness and different phylogenetic structure metrics were explained by altitude and soil properties. Our study revealed that key plant diversity dimensions (i.e. taxonomic and phylogenetic) are shaped by a local-scale edaphic and elevational gradient on an isolated
tepui
of Brazilian Amazonian.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The high mountains of Central Andean represents one of the most diverse and heterogeneous landscape of South America, with very contrasting climates across an east-west gradient that remains poorly ...investigated in terms of Late Quaternary soil formation. Climatic forces within a diverse pedogeomorphological framework generates a complex geoenvironmental scenario, extremely susceptible to climatic changes. From the high aridic bolivian altiplano to moist periglacial regions at high mountain, and from these, to the tropical rainforest downslope, one finds soil chronosequences and different ecosystems. The objective of this work was to describe and interpret chronological, morphological, physical, chemical and mineralogical attributes of 18 profiles along a long and representative east-west transect through the Cordillera Real, at altitudes varying between 1800 and 5030 m a.s.l. The parent material is lithologically diverse, ranging from till, fluvio-glacial, talus and loess sediments. Most soils show a sequence of O, A, C and C/R with high organic carbon contents at surface and subsurface, forming Umbric horizons. Buried, polycyclic organic layers are common and the 14C dating reveals a sequence of processes as one moves away from the glaciated peaks, varying from 1500 to 6000 years (BP). The occurrence of paleo-peatlands and past and present-day hydromorphic areas (bofedales) result in widespread melanization trend, with histic horizons and histosols formation in the bottomlands. The relict, degraded state of bofedales indicates a reduction of waterlogging in the Altiplano in the late Holocene, resulting in increasing water shortage. Inceptisols occur at the high mountain sector, under periglacial conditions and high slope instability and solifluxion. In general soils are acid or high acid, with low base saturation and high Al saturation. High mountain Tundra soils at (5020 m) are exclusively developed on moraines of resistant granodiorite and have low clay content and less mineralogical diversity. Soils at the western slope were affected by the last glaciation and show more diverse mineralogy with cryogenic features under dry, open vegetation (Puna). On the other hand, soils at the eastern slope are associated with a greater climatic variation, varying mineralogical attributes, greater organic carbon mineralization and formation of organometallic complexes. Although most soils show influence of non-crystalline minerals, such as allophanes and amorphous Fe oxides, andic soil properties were apparently absent.
•The tropical Andean has a soil chronosequence.•There is a great variability of soils even in a slightly variable parent materials.•Peatbogs in the Cordillera Real correlates to Holocene climatic optimum.•Allophanes occurs in soils of the Cordillera Real, without andic soil properties.•Melanization, paludization and cryoturbation are the main pedogenic processes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In South America, one of the least addressed regions in paleoecological studies is the Brazilian Semiarid region, composed of vegetation from different biomes and currently marked by an arid climate. ...Although environmental conditions do not favor the formation of palynological sites, previous studies have indicated an expansion of savanna vegetation during the Last Glacial Maximum (LGM). However, more refined analyses with better spatial and temporal resolutions are important for a better understanding of these environments. The region's past reconstructed by models is related to intense climate changes on brief time scales in the Pleistocene and Holocene. Furthermore, paleoclimatic modeling reconstructions that only reproduce atmospheric conditions do not always represent all factors for vegetation formation and dynamics through time. In this work, we aimed to use the combination of bioclimatic and edaphic predictors to build models with machine learning algorithms capable of predicting the current and last 21,000 years' vegetation. Our results show that there is a significant gain in precision in the classification of vegetation formations when edaphic predictors are added. The use of subsurface horizons to generate edaphic attributes also resulted in better details of the local distribution of vegetation. The reconstruction of the past climate showed that the greatest change was promoted during the Heinrich Stadial 1 period; with the retraction of areas of open vegetation formations of the Hyperxerophilous Caatinga, areas of Arboreal Caatinga, Forested Caatinga, and Seasonal Deciduous Forest advanced. The current vegetation cover was established only in the Late Holocene, a period in which the humid conditions of the region allowed occupation by mostly dry vegetation.
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•Joining soil and paleoclimate data allowed new results of vegetation distribution in the past 21 ka of the Brazilian Semiarid•Hyperxerophilous Caatinga has retracted in greater humidity periods and advanced only in the last 0.4 kyr.•The humidity pulses allowed Arboreal/Forested Caatinga and Seasonal Decidous Forest to occupy a larger area.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A degradação dos solos representa um risco atual e futuro de comprometimento de serviços ecossistêmicos. Este trabalho tem como objetivo caracterizar os atributos do solo de uma área degradada e ...fragmentos conservados de Cerrado no Triângulo Mineiro-MG. Para tanto, houve avaliação multitemporal de uma voçoroca por meio de fotogrametria em SIG; realizou-se trabalhos de campos com coletas em 39 pontos amostrais e descrição de 5 perfis de solo, em ambientes previamente estratificados da voçoroca; em laboratório, procedeu-se a determinação de atributos físicos, químicos e de matéria orgânica do solo e; análises estatísticas foram conduzidas. Ao longo do tempo, foi estimada uma evolução da degradação do solo de 62% na área, com avanço de 499,5 m²/ano no período de erosão mais acelerada (1964-1979) para 96,9 m²/ano (2005-2020). A ACP evidencia o ambiente de Mata como o de maior fertilidade, com vetores de matéria orgânica, soma de bases e macro e micronutrientes relacionados; testes estatísticos indicam variações entre as frações granulométricas de ambientes conservados e áreas degradadas e igualdade da matéria orgânica no Cerradão e Mata em detrimento da voçoroca. O manejo da matéria orgânica, visando sua incorporação e aumento no solo, deve ser privilegiado em projetos de restauração ambiental.
Antarctic soils occur in restricted areas, but few integrated studies on soils and landforms have focused in the Antarctic Peninsula. We studied the representative soils of Hope Bay, emphasizing the ...processes of quaternary sedimentation, landforms, soil classification, and distribution. Results show that landforms and soils are closely associated in Hope Bay. Ornithogenic soils are associated with Late Pleistocene to Holocene stable ground moraines; these are currently being destroyed by thermokarst erosion around Lake Boekella. Lithic Haploturbels occur chiefly on shallow rocky terrains whereas Typic Haploturbels are found on patterned ground. In Hope Bay, a much colder climate prevails compared with the South Shetlands, and the widespread permafrost close to the surface warrants strong cryoclastic weathering with active and general gelifraction across different lithologies. The shallow occurrence of permafrost in Hope Bay has a strong regulating effect on soils, retarding leaching and soil development processes. Local soils are, in general, shallow and cryoturbic, and the current pedoenvironment on lowland stable areas was subjected to varying phosphatization on previously weathered sedimentary material. The evidence of phosphatization of a formerly larger area appears to be the main driver of pedogenesis at Hope Bay, and nesting activity by penguins on stable surfaces is capable of enhancing weathering and soil formation.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Prehistoric shell middens, called “sambaquis”, occur along the Brazilian coast, but their geoarchaeological and pedological contexts remain little explored. We characterized micromorphological ...attributes and forms of phosphate of key horizons of a soil at Sambaqui. We identified how pedogenesis may affect archaeological materials, helping interpretations relating to the occurrence of elevated concentrations of phosphate, associated with habitation. Micromorphology and microchemical analysis using SEM/EDS investigated well-studied horizons of these shell midden soils. Phosphate mobility is demonstrated by the occurrence of secondary Ca-phosphates in deeper strata free from artifacts, below the midden. Ca-apatite forms well-defined microaggregates of illuvial/chemical origin. The primary sources of the Ca and P have disappeared, and we suggest they were organic materials and ash rather than the existing fragments of bone apatite or shells present in the overlying archaeoanthrosol. The in situ preservation of denser and larger bone fragments may be attributed to the apatite-rich micromass, which retards Ca-apatite dissolution from bone fragments. The presence of phosphate-rich lower strata without direct anthropic inputs indicates that P leaching and precipitation as secondary forms has occurred during wet climate episodes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Unidades de conservação representam a principal estratégia para a preservação e recuperação de recursos naturais brasileiros. Para nortear o seu planejamento e gestão, informações relativas aos ...geoambientes constituem um referencial integrado indispensável. O objetivo deste estudo foi descrever os aspectos pedológicos associados à identificação, caracterização e mapeamento de geoambientes do Parque Nacional Serra da Mocidade, Roraima, norte do Brasil, de forma a subsidiar o manejo ecológico da unidade. Para a estratificação geoambiental foram avaliados os aspectos pedológicos, geomorfológicos e vegetação. Foram descritos e coletados 19 perfis de solos. A caracterização da vegetação foi realizada
in loco.
Foram descritos quatro pedoambientes, com destaque para os seguintes solos: Espodossolo Humilúvico, Espodossolo Ferri-Humilúvico, Espodossolo Ferrilúvico, Neossolo Quartzarênico, Neossolo Regolítico, Neossolo Flúvico, Plintossolo Háplico, Plintossolo Argilúvico, Gleissolo Melânico e Cambissolo Háplico. Foram identificadas 12 unidades geoambientais. No Parque, destaca-se um contraste entre serras e morrarias da zona florestada e os grandes espaços inundáveis e baixios do pediplano Rio Branco-Rio Negro. Além disso, essa área de conservação possui o mais antigo e, provavelmente, o mais importante conjunto montanhoso granítico-gnáissico do norte amazônico, de grande extensão e topografia complexa. Este estudo evidencia a singularidade de cada geoambiente, subsidiando na definição mais precisa e adequada das formas de manejo do Parque.
In prehistoric times, innumerous shell middens, called "sambaquis", consisting mainly of remains of marine organisms, were built along the Brazilian coast. Although the scientific community took ...interest in these anthropic formations, especially since the nineteenth century, their pedological context is still poorly understood. The purpose of this study was to characterize and identify the physical and chemical changes induced by soil-forming processes, as well as to compare the morphology of shell midden soils with other, already described, anthropogenic soils of Brazil. Four soil profiles developed from shell middens in the Região dos Lagos - RJ were morphologically described and the physical and chemical properties determined. The chemical analysis showed that Ca, Mn, Mg, and particularly P and Zn are indicators of anthropic horizons of midden soils, as in the Amazon Dark Earths (Terras Pretas de Índio). After the deposition of P-rich material, P reaction and leaching can mask or disturb the evidence of in situ man-made strata, but mineralogical and chemical studies of phosphate forms can elucidate the apparent complexity. Lower phosphate-rich strata without direct anthropic inputs indicate P leaching and precipitation in secondary forms. The total and bioavailable contents of Ca, Mg, Zn, Mn, Cu, P, and organic C of midden soils were much higher than of regional soils without influence of ancient human settlements, demonstrating that the high fertility persisted for long periods, at some sites for more than 4000 years. The physical analysis showed that wind-blown sand contributed significantly to increase the sand fraction in the analyzed soils (texture classes sand, sandy loam and sandy clay loam) and that the aeolian sand accumulation occurred simultaneously with the midden formation.
Ao longo do litoral brasileiro foram erigidos, na pré-história, centenas de depósitos, constituídos principalmente por restos de organismos marinhos, denominados sambaquis. Essas formações de origem antrópica despertaram a curiosidade da comunidade científica, especialmente a partir do século XIX; entretanto, permanecem pouco conhecidas no contexto pedológico. Este trabalho objetivou caracterizar e identificar resultados dos processos pedogenéticos, que produziram alterações físico-químicas e morfológicas, bem como comparar solos de sambaquis com outros solos antropogênicos do Brasil, já conhecidos. Quatro perfis de solos desenvolvidos de sambaquis na Região dos Lagos - RJ foram estudados. Os solos foram descritos morfologicamente, e amostras foram coletadas para execução de análises físicas e químicas. As análises químicas revelaram que os elementos Ca, Mn, Mg e, especialmente, P e Zn são indicadores de horizontes antrópicos de solos de sambaquis, à semelhança das Terras Pretas de Índio da Amazônia. Após a deposição de materiais ricos em fósforo, reações e lixiviação podem alterar drasticamente as evidências de camadas feitas pelo homem in situ, porém estudos químicos e mineralógicos das formas de fósforo podem elucidar a complexidade aparente. Horizontes ricos em fósforo sem a deposição direta de materiais antrópicos indicam a lixiviação de P e sua precipitação em formas secundárias. Os teores de Ca, Mg, Zn, Mn, Cu, P e C-orgânico dos solos de sambaquis são muito maiores em comparação aos dos solos regionais sem interferência de antigos assentamentos humanos, o que demonstra a permanência de elevada fertilidade por longo período - em alguns sítios, superior a 4 mil anos. Quanto às análises físicas, elas mostraram que o aporte eólico de areias foi significativo no incremento dessa fração na composição dos solos analisados - todos se mostraram entre as classes texturais areia, franco-arenosa e franco-argiloarenosa - e que o acúmulo de areias eólicas foi contemporâneo à formação dos sambaquis.
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