Swamp forests are associated with soils that are saturated or inundated because of a high water table. In Brazil, little is known about the plant ecology of such forests. In this paper, we aimed to describe the phytosociological structure of the tree layer of swamp forests in Restinga de Jurubatiba National Park, in the northern part of the state of Rio de Janeiro, and to evaluate the floristic similarities between these forests and some other possibly related types of vegetation formations in Brazil. The sampling included 84 species, within 62 genera and 34 families. The Shannon diversity index was 3.42, and the Shannon evenness index was 0.77. The forests studied showed an oligarchic structure; Tapirira guianensis, Calophyllum brasiliense and Protium icicariba were the most important species. Oligarchy, or monodominance, and relatively low species richness are the norm in the swamp forests of southeastern Brazil and result from the strong selective character of the saturated/inundated soils. In comparison with local areas of restinga (coastal woodland), Atlantic Forest sensu stricto, other swamp forests and flooded riparian forests, the similarity was low (Jaccard similarity coefficient < 0.25). In addition to the similar ecological conditions, geographic proximity was a key factor determining the patterns of similarity found. Our results indicate that the swamp forests of southeastern Brazil do not represent a distinguishable floristic unit, due to sources of local variation, notably migration and the establishment of adaptive species from neighboring vegetation formations (some 70% of the species surveyed)

O presente trabalho compara a composição e estrutura de assembléias vegetais de fragmentos florestais, com diferentes características em relação ao tipo de propriedades rurais do entorno, tamanho e histórico de uso, com uma área localizada dentro de uma unidade de conservação (área controle), na bacia do rio Guapiaçu. Em cada fragmento foram delimitadas duas parcelas de 50 x 100m, na mesma orientação sudoeste, no interior das quais foram medidos os DAP (Diâmetro Acima do Peito) e altura de todos indivíduos com DAP ≥ 5 cm e identificados até o menor nível taxonômico possível. A densidade, área basal total, riqueza e diversidade foram calculados. As assembléias foram comparadas quanto aos seus valores diâmétricos e proporção de indivíduos em classes de diâmetro. Os parâmetros fitossociológicos foram calculados e as vinte espécies de maior cobertura foram selecionadas com vistas à comparação da composição específica e de suas caracteríticas sucessionais. Todas as assembleías estudadas apresentam alta riqueza e diversidade de espécies, sendo igualmente constatadas, em relação à área controle, diferenças significativas em pelo menos uma das caracteríticas analisadas. Todas apresentam uma menor proporção de indivíduos nas classes diâmetricas maiores e de espécies secundárias tardias que na área controle. No entanto, para algumas delas correspondem valores totais de diâmetro igual ou maiores que os da área controle por conta da maior proporção de indivíduos em classes diâmetricas intermediárias que parece contribuir mais para o aumento desses valores. De forma geral, há maior abundância de espécies pioneiras e secundárias iniciais nos fragmentos florestais, porém a proporção destas categorias sucessionais varia entre eles evidenciando diferenças dos estágios sucessionais em que se encontram. Estas diferenças poderiam estar relacionadas a certa variabilidade dos distúrbios identificados no entorno. Os resultados obtidos aqui sugerem que fragmentos de mata rodeados por pequenas propriedades encontram-se em estágios sucessionais mais inicias e sujeitos a distúrbios mais severos.

This work synthesises information about plant diversity of 37 sites of coastal and inland swamp forests of southeast and southern Brazil and investigates floristic similarities and differences among them. Swamp forests often show low species richness, diversity and evenness, which are associated with the selective character of oxygen deprivation caused by soil waterlogging. However, our results pointed out some degree of site-level variation (Sobs = 5 to 110; Sjack1 = 6 to 151; H′ = 0.82 to 3.98; J′ = 0.51 to 0.87) related to local ecological conditions. Two major phytogeographical patterns emerged from our work: the strong influence of the neighbouring non-flooded vegetation on the flora of swamp forests and its high spatial heterogeneity. At least 85.9% of the 518 species sampled are found in neighbouring non-flooded vegetation. A correspondence analysis consistently separated swamp forests of the coastal plain from those of the plateau. A Mantel test indicated a significant correlation between floristic and geographical distances among sites (r = 0.45; p = 0.001), and highlighted the main effect of regional-scale changes in the flora of swamp forests. We conclude that swamp forests of southeast and southern Brazil cannot be considered a distinguishable floristic unit.

O município de Armação dos Búzios, RJ, faz parte da região de Cabo Frio, considerada um dos 14 Centros de Diversidade Vegetal do Brasil. Para a caracterização da composição florística e estrutura do componente arbustivoarbóreo (DAP > 5 cm) de florestas sobre maciços litorâneos deste município, foram implantados cinco blocos de cinco parcelas de 10 x 20 m, distribuídos em diferentes encostas (total de 0,5 ha). Foram amostrados 1193 indivíduos, 98 espécies e 36 famílias. Myrtaceae e Fabaceae (20 e 11 espécies) destacaram-se em riqueza e Euphorbiaceae, em número de indivíduos (39% do total). As espécies mais importantes foram Pachystroma longifolium (VI = 31,9), Sebastiania nervosa (30,6), Chrysophyllum lucentifolium (11,3), Machaerium pedicellatum (10,5), Guapira opposita (9,9), Philyra brasiliensis (9,9), Capparis flexuosa (9,1), Lonchocarpus virgilioides (8,2), Syagrus romanzoffiana (7,6) e Acosmium lentiscifolium (7,5). O índice de Shannon (H') foi de 3,60 nat.ind.^-1 e a equabilidade (J') foi de 0,79. A distribuição espacial das espécies parece estar condicionada às características ecológicas de cada encosta, como resultado de sua orientação. As florestas estudadas apresentaram, em geral, similaridade (Jaccard) muito baixa com outras florestas fluminenses.

Studies of the vegetation on islands off the coast of southeastern Brazil are still very scarce, despite their importance for assessing, managing, and conserving insular biodiversity. We present here a list of the vascular flora of Queimada Grande Island (QGI; 24°29′10″ S, 46°40′30″ W, 57 ha, 33.2 km from the coast) in southeastern Brazil and describe its phytophysiognomies. The island is covered mainly by Atlantic Forest (Dense Ombrophilous Forest), as well as with rock outcrop and anthropogenic vegetation with herbaceous-shrub phytophysiognomies. QGI showed relatively low species richness (S = 125) when compared to other Brazilian coastal islands. Herbaceous (52) and climbing species (31) predominated on QGI. The richest families were Fabaceae (11 species), Poaceae (9), and Apocynaceae, Asteraceae and Orchidaceae (8 species each). Most species (S = 112) are autochthonous from different phytophysiognomies of the southeastern Brazilian Atlantic Forest complex. Many species associated with anthropically disturbed areas (S = 26) can be found on QGI, including the invasive grass Melinis minutiflora. There was a slight predominance of zoochory (S = 50). We did not identify any species endemic to QGI. One of its species (Cattleya intermedia, Orchidaceae) is vulnerable at both national and regional levels, and another (Barrosoa apiculata, Asteraceae) is presumably extinct on the mainland in São Paulo State. The vascular flora of QGI originated from the mainland Atlantic Forest complex, following the pattern of other coastal islands in southeastern Brazil. The flora and vegetation of QGI reflect the combination of insular conditions, the small size of the island, habitat restriction, steep topography, incipient soils, and the past use of the area with the introduction of several foreign species. We recommend permanent monitoring of the vegetation cover of QGI and its management, in order to ensure the conservation of the local native biota.

In the present study a specific and comprehensive analysis of the arboreal flora of Ilha Grande, located in the municipality of Angra dos Reis, on the southern coast of the state of Rio de Janeiro, Brazil, is presented. Unpublished data and contributions from studies already carried out at the site that investigated issues related to the composition and richness of tree species, the degree of threat, endemism and the history of occupation and/or changes in land use were gathered and analyzed. This study is part of the PPBio Mata Atlântica – Programa de Pesquisa em Biodiversidade (Biodiversity Research Program) which, through phytosociological inventories of the tree component, has been contributing, since 2010, to the increase in the floristic knowledge of Ilha Grande. The inventory identified 509 tree species, belonging to 220 genera and 74 families. Of these, 34 species were categorized as threatened, two of which are critically endangered, 18 are endangered and 14 are vulnerable. 53 exotic tree species were indicated. The results presented here reinforce the importance of these inventories as indispensable tools for the construction of strategies and actions for conservation, restoration and management of diversity in the context of the Atlantic Forest.