Composição florística e cobertura vegetal das savanas na região de Alter do Chão, Santarém - PA

Magnusson, William E.; Lima, Albertina P.; Albernaz, Ana Luisa; Sanaiotti, Tânia Margarete; Guillaumet, Jean-Louis

doi:10.1590/s0100-84042008000100015

Cited by 42 publications

(43 citation statements)

References 23 publications

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“…The percentage covered by Poaceae observed in the present study was greater than was found previously in western Pará (Magnusson et al 2008), where eight species of Poaceae were identified, with only two of them dominant (Paspalum carinatum and Trachypogon spicatus), although the total coverage of the family was 40.06%. In the savannas within the state of Roraima, Poaceae comprised only 19% of the herbaceous stratum in a survey performed by Takeuchi (1960) and 43.40% in a study conducted by Miranda & Absy (1997).…”

Section: Discussioncontrasting

confidence: 84%

“…The Mangaba savanna exhibited the highest coarse sand content and the lowest clay content, potentially influencing water and nutrient availability (Barros et al 2009) and, consequently, the predominance of Axonopus polydactylus (38.47%), a species common to coastal woodlands (Cialdella et al 2006), where the soil is low in clay and organic matter, with low water and nutrient retention capacity (Cuzzuol & Campos 2001). This may be one of the few savanna areas in the Amazon, if not the only area, where two Axonopus species dominate the herbaceous stratum (Takeuchi 1960;Coradin 1978;Bastos 1984;Allem & Valls 1987;Miranda & Carneiro 1994;Miranda & Absy 2000;Baruch 2005;Magnusson et al 2008;Viana & Filgueiras 2008).…”

Section: Discussionmentioning

confidence: 99%

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Poaceae communities in the savannas of the Amazon Estuary in Brazil

Rocha

Miranda²

2014

Acta Bot. Bras.

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We sought to identify the major environmental factors that affect the diversity and distribution of Poaceae in the savannas of the Amazon Estuary. The study was conducted across seven areas of savanna in the Amazon Estuary, within which 160 subplots of 1 m 2 each were established within four 10 × 100 m plots. Soil samples were collected at a depth of 0-20 cm. A total of 24 Poaceae species were recorded. Only two were common to all of the areas studied (Axonopus aureus P. Beauv. and Anthaenantia lanata (Kunth) Benth). The edaphic factors that most influenced the Poaceae in the savannas studied were organic matter, coarse sand, and silt contents. Conversely, rainfall had no effect. The floristic and structural characteristics of the savannas studied suggest that Poaceae communities exhibit low diversity and a peculiar distribution pattern in which a group of species predominate in a given stretch, creating a homogeneous physiognomy. Our findings suggest that the structure of these communities is related to a gradient of soil texture, the percentage of Axonopus and Trachypogon coverage increasing and decreasing, respectively, along that gradient. These data can contribute to the understanding of plant-soil interactions in this environment, promoting strategies for conservation, management, and revegetation.

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Section: Discussioncontrasting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Poaceae communities in the savannas of the Amazon Estuary in Brazil

Rocha

Miranda²

2014

Acta Bot. Bras.

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“…being considered generalists able to prosper in a variety of environments (Cavalcanti and Tabarelli 2004). Forty species are known to occur in FF and savanna areas in other regions of the country (Northeast, Central-West and Southeast), and in Alter do Chão 33 of these were found in the FF (Magnusson et al 2008).…”

Section: Resultsmentioning

confidence: 99%

Disentangling structural patterns of natural forest fragments in a savanna matrix in the eastern Brazilian Amazon

et al. 2017

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Natural fragments are an important source of richness for the management and conservation of a local flora. The objective of this study was to evaluate the effect of fragmentation on the structure and composition of the plant communities of forest fragments (FF) in Alter do Chão, eastern Brazilian Amazonia. The study sample consisted of 25 FF and nine continuous forest (CF) sites. We compared plant density and species richness between site categories by t-tests, analyzed the differences in composition by cluster analysis, and assessed the effect of fragment size and distance to CF on the basal area and diameter of FF assemblages by linear regression. Individual trees and shrubs with DBH ≥1.27 cm were measured in 2x250 m plots. 17,078 individuals were recorded -75.32% in FF and 24.68% in CF, comprising 475 species, 216 genera and 64 families. Myrtaceae and Fabaceae were the most abundant families in both FF and CF. Average species richness in FF and CF was statistically different. The 20 species with the highest importance values were similar in FF and CF. The average plant diameter was similar in FF and CF, suggesting that both are "mature" forests composed of thin individuals. Average diameter and total basal area showed a negative relationship with distance to CF and fragment area, respectively. Similarity analysis revealed two groups, one composed exclusively of portions of fragmented forest. Fragments and continuous forest differed in species composition, but were similar in structure. Diameter distribution in fragments was similar to that of primary forests. KEYWORDS: Bray-Curtis, Cluster analysis, diameter structure, small trees. Desvendando padrões estruturais de fragmentos florestais na Amazônia Oriental RESUMOFragmentos naturais constituem importante fonte de recursos para o manejo e conservação da flora local. Este trabalho avaliou o efeito da fragmentação sobre a estrutura e a composição das comunidades de plantas de fragmentos florestais (FF), em Alter do Chão, na Amazônia oriental brasileira. Foram amostrados 25 sítios em FF e nove em floresta contínua (CF). Analisamos a diferença na densidade de plantas e na riqueza de espécies entre FF e CF por teste-t, e na composição por análise de agrupamento. Utilizou-se regressão linear para avaliar o efeito do tamanho dos fragmentos e distância à CF sobre a área basal e diâmetro. Os indivíduos com DAP ≥1,27 cm foram medidos em parcelas de 2x250 m. Foram registrados 17.078 indivíduos, 75,32% nos FF e 24,68% na CF, distribuídos em 475 espécies, 216 gêneros e 64 famílias. As famílias Myrtaceae e Fabaceae foram as mais abundantes em ambos FF e CF. A riqueza média diferiu significativamente entre FF e CF. As 20 espécies com maior valor de importância foram semelhantes nos FF e CF. O diâmetro médio nos FF e CF foi semelhante, sugerindo tratar-se em ambos casos de florestas "maduras" compostas por indivíduos finos. O diâmetro médio e a área basal total mostraram relação negativa com a distância à CF e área dos fragmentos, respectivamente. A análise de simil...

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“…Os poucos estudos existentes desenvolveram suas investigações principalmente com comunidades arbóreo-arbustivas abordando florística e estrutura (Barbosa et al 2005;Miranda et al 2006) ou distribuição espacial em função de fatores ambientais (Miranda et al 2002). Pouca atenção tem sido dada às comunidades de plantas herbáceas, embora seja reconhecido que este componente apresente grande diversidade em campos e savanas da Amazônia (Miranda e Absy 2000; Magnusson et al 2008).…”

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“…Os resultados desse estudo indicam maior riqueza de plantas herbáceas da família Leguminosae em relação às 15 espécies verificadas na savana de Alter do Chão (PA) por Magnusson et al (2008). Contudo, os resultados dessa investigação são plenamente compatíveis com levantamentos Figura 2 -Dendrograma de dissimilaridade indicando a distância florística (%) entre as parcelas e a distribuição das espécies.…”

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Fatores edáficos determinando a ocorrência de leguminosas herbáceas em savanas amazônicas

2014

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RESUMOFatores edáficos vem sendo indicados como determinantes para a distribuição de comunidades de plantas na Amazônia. O objetivo deste estudo foi investigar quais fatores edáficos determinam a ocorrência de leguminosas herbáceas em savanas amazônicas. Para tanto, foi realizado um inventário da flora herbácea da família Leguminosae em 34 parcelas permanentes estabelecidas em duas áreas de savana de Roraima, norte da Amazônia brasileira. As espécies Chamaecrista desvauxii (24,9%), Aeschynomene histrix (15,7%) e Galactia jussiaeana (10,8%) foram as de maior índice de valor de importância. Todas com grande abundância e ampla distribuição. Os resultados indicaram baixa densidade ou ausência de indivíduos e espécies em parcelas estabelecidas em solos mal drenados (hidromórficos). Diversidade e riqueza de espécies tendeu a ser maior em habitats formados por solos bem drenados, mais férteis e com menor concentração de alumínio trocável. É sugerido que solos pobres e sazonalmente alagados reduzam as chances de ocorrência e afetem negativamente a riqueza/diversidade de leguminosas herbáceas nas áreas de savana de Roraima. PALAVRAS-CHAVE: ecologia de comunidades, cerrado, lavrado, Roraima Edaphic factors determining the occurrence of herbaceous legumes in Amazonian savannas ABSTRACTEdaphic factors have been indicated as a determinant of the distribution of plant communities in Amazonia. The aim of this study was to detect which edaphic factors determine the occurrence of herbaceous legumes in Amazonian savannas. Therefore, an inventory of herbaceous flora of the family Leguminosae was conducted in 34 permanent plots established in two savanna areas of Roraima, northern Brazilian Amazon. The importance value index was higher for Chamaecrista desvauxii (24.9%), Aeschynomene hystrix (15.7%) and Galactia jussiaeana (10.8%), all having high abundance and wide distribution. The results indicated low density or absence of individuals and species in plots established on poorly drained soils (hydromorphic). Diversity and species richness tended to be higher in habitats formed on well drained soils, greater fertility and lower concentrations of exchangeable aluminum. It is suggested that poor and seasonally flooded soils tend to reduce the chances of occurrence of herbaceous legumes in savanna areas of Roraima, adversely affecting its richness/diversity.

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Composição florística e cobertura vegetal das savanas na região de Alter do Chão, Santarém - PA

Cited by 42 publications

References 23 publications

Poaceae communities in the savannas of the Amazon Estuary in Brazil

Poaceae communities in the savannas of the Amazon Estuary in Brazil

Disentangling structural patterns of natural forest fragments in a savanna matrix in the eastern Brazilian Amazon

Fatores edáficos determinando a ocorrência de leguminosas herbáceas em savanas amazônicas

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