Relações Solo–vegetação Em “Ilhas” Florestais E Savanas Adjacentes, No Nordeste De Roraima

Feitosa, Keily Katiany Almeida; Júnior, José Frutuoso do Vale; Schaefer, Carlos Ernesto Gonçalves Reynaud; Sousa, Maria Ivonilde Leitão de; Nascimento, Pedro Paulo Ramos Ribeiro

doi:10.5902/1980509821098

Cited by 21 publications

(25 citation statements)

References 6 publications

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“…Due to the extensive territorial dimensions and the limited accessibility, studies of soils in the Amazon have mainly been based on local scales and on toposequences (Chauvel, 1981;Bernoux et al, 1998;Feitosa et al, 2016). However, in the 1970s an exploratory survey of the soils of this region was conducted, called the RADAM project (Brasil, 1973), and contributed significantly to increasing the knowledge on the soils and their environmental interpretations (Sanchez et al, 1982;Rodrigues, 1996;Nepstad et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Multivariate Analysis and Machine Learning in Properties of Ultisols (Argissolos) of Brazilian Amazon

Souza

Thomazini

Schaefer

et al. 2018

Rev. Bras. Ciênc. Solo

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Ultisols are the most common soil order in the Brazilian Amazon. The Legal Amazon (LA) has an area of 5 × 10 6 km 2 , with few accessible areas, which restricts studies of soils at a detailed level. The pedological properties can be estimated more efficiently using statistical procedures and machine learning techniques, tools which are capable of recognizing patterns in a large soil database. We analyzed the main chemical and physical properties of the B horizons of the Ultisols of the Brazilian Amazon, as well as the spatial variability of the most explanatory properties of these horizons. Physical and chemical data of 1,068 profiles of the RadamBrasil Project were used. A principal component analysis (PCA) was applied and the most explanatory variables were separated by morphostructural units and climate zones. The technique of machine learning was used for spatialization of the explanatory variables based on predictive covariates. In general, the horizons are thick, clay, with a predominance of negative charges, and low levels of exchangeable cations. The variables retained in the PCA were: sum of bases (SB), Al 3+ , degree of flocculation (Floc), ∆pH, and organic carbon content (C). Areas of greater precipitation have low SB, with higher values in the basement complex (BC) and in areas under the Andean influence. Higher levels of Al 3+ and degrees of flocculation were also associated with greater precipitation. However, the soils are predominantly electronegative, showing a kaolinitic mineralogy. The C contents in general were low, with an increase in more humid zones due to the process of mineralization and illuviation (podzolization), and in the BC due to the protection of C by the aggregation of clay. The use of multivariate analysis allowed a better understanding of the Ultisols' main properties in different morphostructural and climatic domains, and its spatialization facilitated the interpretation of properties and their relationships with environmental characteristics in the Legal Amazon.

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Section: Introductionmentioning

confidence: 99%

Multivariate Analysis and Machine Learning in Properties of Ultisols (Argissolos) of Brazilian Amazon

Souza

Thomazini

Schaefer

et al. 2018

Rev. Bras. Ciênc. Solo

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“…However, these environments were less acidic than the peatland soils studied by Zinck (2011) in the savannas of Venezuela and Guyana. These environments, in terms of acidity, resemble the dryland soils of the savannas of the northern Amazonia, studied by Benedetti et al (2011) and Feitosa, Vale Júnior, Schaefer, Sousa, & Nascimento (2016). This high acidity results from the advanced weathering of savanna soils, characteristic of tropical regions and low levels of bases.…”

Section: Chemical Characterization Of Soils In Lakes and Buriti Riparianmentioning

confidence: 85%

Chemical of Soils With Histic Horizon of Lakes and Riparian of the Savanna, Northern Amazonia, Brazil

Duarte¹,

Melo²,

Novotny³

et al. 2018

JAS

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The savanna of the northern Amazon of Brazil is an ecosystem that presents lakes and riparian of buriti (Mauritia flexuosa L.) in its landscape. Although these ecosystems are protected by law, they are subject to changes by anthropization in their surrounding areas. The soils of lakes and on the banks of the buriti riparian of the savanna of Boa Vista, Northern Amazonia, are hydromorphic and, although they are important ecosystems for the environmental sustainability, they are little studied. Thus, the purpose of this work was to characterize the chemical composition of these soils and relate the results to the type of anthropization. Samples were collected at the margins of five riparian and three lakes in the 0.0-0.1, 0.1-0.2, 0.2-0.3, 0.3-0.4, and 0.4-0.5 m depth layers. Soil samples, in each environment, were taken from three points equidistant at 100 m. For soil characterization, pH in water, H + Al, Al3+, P, K+, Mg2+, Ca2+, and total organic C (TOC) were determined. The soils of lakes and buriti riparian are of high acidity, low natural fertility, and high toxicity by Al. Buriti riparian presented the highest levels of TOC but were also the environments most susceptible to the effects of anthropization, in which Bom Intento presented values of available P from medium to high by the interference of agricultural activities.

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“…The expansion of a few pioneer, white‐sand specialist trees over the sand dunes may have facilitated the establishment of generalist tree species originated from the surrounding forests, with the most important environmental modifications possibly being the incremental soil organic matter, tree root stabilization, and the emergence of understory individuals with mild microclimatic requirements. Both inside Viruá megafan and elsewhere soils underlying Amazonian white‐sand forests have higher contents of organic matter than adjacent grassland/shrubland soils (Barbosa and Ferreira, ; Mendonça et al ., ; Feitosa et al ., ; Vale Junior et al ., ). Concentrations of K, P and the sum of bases were also higher in white‐sand forest soils than grasslands, which may be related to the organic matter cycling (Mendonça et al ., ; Feitosa et al ., ).…”

Section: Discussionmentioning

confidence: 99%

“…Both inside Viruá megafan and elsewhere soils underlying Amazonian white‐sand forests have higher contents of organic matter than adjacent grassland/shrubland soils (Barbosa and Ferreira, ; Mendonça et al ., ; Feitosa et al ., ; Vale Junior et al ., ). Concentrations of K, P and the sum of bases were also higher in white‐sand forest soils than grasslands, which may be related to the organic matter cycling (Mendonça et al ., ; Feitosa et al ., ). The release of biotic components by the action of micro‐organisms in decomposing litter further induces root growth (St John and Machado, ).…”

Section: Discussionmentioning

confidence: 99%

The influence of late Quaternary sedimentation on vegetation in an Amazonian lowland megafan

Rossetti

Gribel

Tuomisto

et al. 2018

Earth Surf Processes Landf

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The largest areas of white‐sand vegetation in northern Amazonia are confined to Late Pleistocene–Holocene megafan depositional systems, which suggest a relationship between the two. The aim of this work is to determine: (i) the relative role of sedimentary history and recent ecological processes to explaining the mosaic of white‐sand forest patches, grasslands and shrublands in a wetland area of northern Amazonia; and (ii) the long‐term successional trajectory that led to the establishment of the white‐sand forest patches. Facies analysis was used to reconstruct the megafan paleoenvironment; δ13C, total organic carbon and carbon/nitrogen from sedimentary organic matter to reconstruct the past vegetation; and floristic inventories to characterize the modern vegetation. The results revealed that the Viruá megafan consists of various sandy sub‐environments, including aeolian sand dunes and sheets developed mostly in the Holocene after the megafan turned inactive as a depositional site. Dune margins and tops are colonized by white‐sand trees mixed with a few generalist rain‐forest species, whereas adjacent lower‐lying areas, which are affected by seasonal flooding, are covered by graminoid plants and/or shrubs. The latter initiated their development over the megafan surface in different times of the Holocene due to hydrological gradients imposed by the topography of the various megafan depositional environments, while the white‐sand forest became dominant only on sand dunes over the last few centuries. We suggest that the late Quaternary sedimentary history was crucial in creating morphologies that now determine topographic gradients responsible for different vegetation physiognomies over the Amazonian lowlands. Copyright © 2017 John Wiley & Sons, Ltd.

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Relações Solo–vegetação Em “Ilhas” Florestais E Savanas Adjacentes, No Nordeste De Roraima

Cited by 21 publications

References 6 publications

Multivariate Analysis and Machine Learning in Properties of Ultisols (Argissolos) of Brazilian Amazon

Multivariate Analysis and Machine Learning in Properties of Ultisols (Argissolos) of Brazilian Amazon

Chemical of Soils With Histic Horizon of Lakes and Riparian of the Savanna, Northern Amazonia, Brazil

The influence of late Quaternary sedimentation on vegetation in an Amazonian lowland megafan

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