Os solos da reserva Ecológica de Maracá, Roraima: Segunda aproximação.

Robison, Daniel M.; Nortcliff, Stephen

doi:10.1590/1809-43921991211424

Cited by 11 publications

(8 citation statements)

References 4 publications

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“…The plots were located in a dissected plinthite landscape (Robison & Nortcliff 1991), with a predominance of soils of podzdico vermelh+amarelo, plintico, and textura arenosa (red-yellow podzolic, plinthic, and sandy textured; EMBRAPA 1981), which corresponds to Grossarenic Plinthic Paleudults (USDA 1975). The soils had similar physical characteristics in all plots and were very sandy (78-86 %), well drained, and acidic, with low concentrations of extractable N, P, and exchangeable cations (Nascimento et al 1997, Villela 1997 …”

Section: Study Areamentioning

confidence: 99%

Leaf Litter Decomposition and Monodominance in the Peltogyne Forest of Maracá Island, Brazil1

Villela

Proctor

2002

Biotrop

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The forest type dominated by Peltogyne gracdipes (Caesalpiniaceae) on the riverine Marad Island is the least speciesrich of any recorded for Brazilian Amazonia. Because the forest has high soil and foliar Mg concentrations, and Mg is known to be toxic to plant growth at high concentrations, this study tested the hypothesis that dominance by Peltogyne is related to Mg leaf litter amounts and decomposition. We predicted that decomposition of PeItogyne leaves would differ from that of other species, and that their decomposition would result in a pulse of Mg release, Three plots (50 X 50 m) were established in each of three forest types: Peltogyne-rich forest (PRF; dominated by Pgracilipes), Peltogynepoor forest (PPF), and forest without Peltogyne (FWP). Three leaf litter decomposition experiments tested if decomposition of mixed leaf litter in coarse-mesh (CM) litterbags differed among forests (experiment 1); whether or not decomposition and nutrient release of Ecclinusa pianensis, Lucbeopsis duckeana, and Peltogyne in CM litterbags differed among forests and species (experiment 2); and using fine-mesh (FM) litterbags, investigated the differences in the influence of faunal activity on Ecclinusa and Peltogyne decomposition (experiment 3). Decomposition was independent of the presence and dominance of Peltogyne, since decomposition rates in both PRF and FWF' were in general lower than in PPF. These differences appeared to be related to faunal activity. The decomposition of Peltogyne leaves was lower than that of the other species tested and was more affected by microbial and physical action. It is possible that the monodominance of PeItogyne is related to its deciduousness and faster decomposition in the dry season, which coincides with a large leaf fall. Magnesium was lost quickly from the PeItogyne leaves and the resultant pulses of Mg into the soil during the heavy rains at the beginning of the wet season may be deleterious for other species that are not adapted to high solution Mg concentrations. Results obtained were consistent with the hypothesis that PeItogyne dominance is related to the pattern of its leaf decomposition and the seasonal pulses of toxic Mg. RESUMOA floresta dominada por Peltogyne gracili$es (Caesalpiniaceae) na Ilha fluvial de Marad t a mais pobre em esptcies reportada para a Amazania brasileira. Devido a esta floresta possuir altas concentrapks de Mg no solo e nas folhas, e pel0 fato de Mg ser conhecidamente t6xico para o crescimento das plantas quando em alms concentra+es, este estudo testou a hip6tese de que a dominhcia de Peltogyne esd relacionada corn as quantidades de Mg e corn a decomposieo das folhas da serrapilheira. Esperou-se encontrar um padrzo de decomposigo diferente para folhas de Peltogyne, e que as folhas de Peltogyne apresentassem urn pulso de liberago de Mg. Tr& parcelas (50 X 50 m) foram estabelecidas em cada um dos tres tipos florestais: floresta r i a em PeItogyne (PRF; dominada por Pgrmilipes), floresta pobre em Peltogyne (PPF) e floresta sem Peltogyne (FWF'). Tres exper...

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Section: Study Areamentioning

confidence: 99%

Leaf Litter Decomposition and Monodominance in the Peltogyne Forest of Maracá Island, Brazil1

Villela

Proctor

2002

Biotrop

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“… Soil, drainage, and relief classes were derived from field observations in association with the studies by Robison and Nortcliff () and Villacorta (). …”

Section: Methodsmentioning

confidence: 99%

“…The vegetation of Maracá is characterized by an ecotone zone formed by contact of the continuous forest formations with the large savanna area located in the northern part of the Brazilian Amazon, between the Rupununi and Branco River basins (Barbosa, Campos, Pinto, & Fearnside, ; Milliken & Ratter, ). The continuous forest is characterized by a mosaic of ombrophilous and seasonal forests that occur on different soil and drainage types (Nortcliff & Robison, ; Robison & Nortcliff, ).…”

Section: Methodsmentioning

confidence: 99%

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Amazon soil charcoal: Pyrogenic carbon stock depends of ignition source distance and forest type in Roraima, Brazil

Carvalho

Fearnside

Nascimento

et al. 2018

Global Change Biology

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Pyrogenic carbon (PyC) derived from charcoal particles (paleo + modern) deposited in the soil column has been little studied in the Amazon, and our understanding of the factors that control the spatial and vertical distribution of these materials in the region's forest soils is still unclear. The objective of this study was to test the effect of forest type and distance from the ignition source on the PyC stocks contained in macroscopic particles of soil charcoal (≥2 mm; 1 m depth) dispersed in ecotone forests of the northern Brazilian Amazon. Thirty permanent plots were set up near a site that had been occupied by pre-Columbian and by modern populations until the late 1970s. The sampled plots represent seasonal and ombrophilous forests that occur under different hydro-edaphic restrictions. Our results indicate that the largest PyC stock was spatially dependent on distance to the ignition source (<3 km), occurring mainly in flood-free ombrophilous forests (3.46 ± 5.22 Mg PyC/ha). The vertical distribution of PyC in the deeper layers of the soil (> 50 cm) in seasonal forests was limited by hydro-edaphic impediments that restricted the occurrence of charcoal. These results suggest that PyC stocks derived from macroscopic charcoal particles in the soil of this Brazilian Amazon ecotone region are controlled by the distance from the ignition source of the fire, and that forest types with higher hydro-edaphic restrictions can inhibit formation and accumulation of charcoal. Making use of these distinctions reduces uncertainty and improves our ability to understand the variability of PyC stocks in forests with a history of fire in the Amazon.

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“…Soil classes vary with relief and drainage, where hills and slopes (well-drained soils) are dominated by quartzite or granite with a predominance of rocks that are rich in bases, while in the lowlands (poorly VOL. 49(2) 2019: 81 -90 ACTA AMAZONICA drained soils) there is a dominance of hydromorphic soils (Robison and Nortcliff 1991). Maracá has climatic seasonality and is located in a border zone between the "Aw" and "Am" climatic sub-types in the Köppen classification (Barbosa 1997).…”

Section: Study Areamentioning

confidence: 99%

Allometric models to estimate tree height in northern Amazonian ecotone forests

et al. 2019

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Allometric models defining the relationship between stem diameter and total tree height in the Amazon basin are important because they refine the estimates of tree carbon stocks and flow in the region. This study tests different allometric models to estimate the total tree height from the stem diameter in an ecotone zone between ombrophilous and seasonal forests in the Brazilian state of Roraima, in northern Amazonia. Stem diameter and total height were measured directly in 65 recently fallen trees (live or dead).Linear and nonlinear regressions were tested to represent the D:H relation in this specific ecotone zone. Criteria for model selection were the standard error of the estimate (S yx ) and the adjusted coefficient of determination (R² adj ), complemented by the Akaike Information Criterion (AIC). Analysis of residuals of the most parsimonious nonlinear models showed a tendency to overestimate the total tree height for trees in the 20-40 cm diameter range. Application of our best fitted model (Michaelis-Menten) indicated that previously published general equations for the tropics that use diameter as the independent variable can either overestimate tree height in the study area by 10-29% (Weibull models) or underestimate it by 8% (climate-based models). We concluded that our site-specific model can be used in the ecotone forests studied in Roraima because it realistically reflects the local biometric relationships between stem diameter and total tree height. Studies need to be expanded in peripheral areas of northern Amazonia in order to reduce uncertainties in biomass and carbon estimates that use the tree height as a variable in general models. Modelos alométricos para estimar altura de árvores em florestas ecotonais do norte da Amazônia RESUMOModelos alométricos que definem o relacionamento entre diâmetro do tronco e a altura total da árvore na bacia amazônica são importantes porque refinam as estimativas de fluxo e estoques de carbono arbóreo na região. Este estudo testou diferentes modelos alométricos para estimar a altura total de árvores a partir do diâmetro do tronco em uma zona de ecótono entre florestas ombrófilas e sazonais no estado de Roraima, norte da Amazônia. Diâmetro do tronco e altura total foram medidos de forma direta em 65 árvores tombadas recentemente (vivas e mortas). Regressões linear e não-linear foram testadas para representar a relação D:H nesta zona específica de ecótono. Os critérios de seleção dos modelos foram o erro padrão da estimativa (S yx ), o coeficiente de determinação ajustado (R² adj ) e o Critério de Informação de Akaike (AIC). A análise dos resíduos dos modelos não-lineares mais parcimoniosos mostrou uma tendência de superestimar a altura total para árvores entre 20-40 cm de diâmetro do tronco. A aplicação do modelo melhor ajustado (Michaelis-Menten) indicou que equações gerais publicadas previamente para os trópicos que usam diâmetro como variável independente podem superestimar em 10-29% (modelos Weibull) ou subestimar em 8% (modelos baseados no clima) a altura da...

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Os solos da reserva Ecológica de Maracá, Roraima: Segunda aproximação.

Cited by 11 publications

References 4 publications

Leaf Litter Decomposition and Monodominance in the Peltogyne Forest of Maracá Island, Brazil1

Leaf Litter Decomposition and Monodominance in the Peltogyne Forest of Maracá Island, Brazil1

Amazon soil charcoal: Pyrogenic carbon stock depends of ignition source distance and forest type in Roraima, Brazil

Allometric models to estimate tree height in northern Amazonian ecotone forests

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