RESUMODiante da importância ecológica que as florestas ciliares representam para o equilíbrio ambiental, este estudo objetiva indicar espécies nativas para serem usadas na recomposição de florestas ciliares degradadas existentes na sub-bacia do Rio Peixe-Boi. Foram inventariadas todas as árvores e arbustos com diâmetro a 1,30 m do solo > 5 cm em dez áreas de floresta secundária e seis de floresta de igapó. Os dados foram analisados pela Análise de Componentes Principais (ACP) e as espécies avaliadas silviculturalmente através de revisão bibliográfica. As áreas de igapó tiveram baixo índice de riqueza e diversidade de Shannon, quando comparado com os dados das florestas secundárias. A composição florística dos igapós foi bem heterogênea, e há maior similaridade florística entre áreas de maior proximidade geográfica. As florestas secundárias tiveram grande abundância de indivíduos, alta riqueza, diversidade e equabilidade e foram agrupadas em função da proximidade geográfica e da idade, o que está diretamente ligado ao estádio sucessional. A análise ACP estabeleceu a importância ecológica de 29 espécies arbóreas, contudo, foram encontradas informações silviculturais de apenas dez espécies. Por apresentarem grande importância ecológica e técnicas silviculturais viáveis e disponíveis na literatura, as espécies de igapó Carapa guianensis, Pachira aquatica, Spondias mombin, Tapirira guianensis e Virola guianensis são as mais indicadas para a recomposição dessas áreas, em associação com as espécies Inga edulis, Jacaranda copaia, Pseudopiptadenia psilostachya, Simarouba amara e Vismia guianensis de floresta secundária, que podem ser plantadas nas áreas de bordas e adjacentes às florestas de igapó. Palavras-chave: Amazônia; capoeiras; igapós; silvicultura. ABSTRACTThis study aims to indicate native species to be used in the restoration of degraded riparian forests in the subwatershed of Peixe-Boi river. All trees and shrubs with diameter at breast height (DBH) > 5 cm were inventoried in ten areas of secondary forest and six areas of igapó forest. The results were analyzed by Principal Component Analysis and the silviculture of the species was assessed by literature review. In Igapó areas 66 species were found; the areas had low richness and low diversity index of Shannon, when compared with data from the secondary forests. The floristic composition was heterogeneous, and the floristic similarity is higher between areas that are closer geographically. In the secondary forests were found 175 species; the areas showed high abundance of individuals, high species richness, diversity and evenness. Secondary forests were separated according to geographic proximity and age, which is directly linked to the successional stage. The PCA analysis established the ecological importance of 29 tree species; however only ten species had enough silvicultural information. Due to a greater ecological importance and viable silvicultural techniques available in the literature, Carapa guianensis,

We studied the tree-regeneration patterns in three distinct agricultural settlements in the Eastern Amazon to test the influence of land-use mosaics. The following questions are addressed: are the floristic structure and composition of regenerating trees affected by the various land-use types applied in the agricultural settlements? Do tree-regeneration patterns respond similarly to distinct land-use mosaics? Is there a relationship between tree regeneration and soil characteristics among the land-use types? The regeneration was inventoried at 45 sampling points in each settlement. At each sampling point, fourteen soil variables were analyzed. Nine different land-use types were considered. The floristic structure and composition of the settlements showed differences in the density of individuals and species and high species heterogeneity among the land-use types. The maximum Jaccard similarity coefficient found between land-use types was only 29%. Shade-tolerant species were the most diverse functional group in most land-use types, including pasture and annual crops, ranging from 91% of the number of species in the conserved and exploited forests of Travessão 338-S to 53% in the invaded pastures of Maçaranduba. The land-use types influenced significantly the floristic structure and composition of regenerating trees in two agricultural settlements, but not in third the settlement, which had greater forest cover. This finding demonstrates that the composition of each land-use mosaic, established by different management approaches, affects regeneration patterns. Tree regeneration was related to soil characteristics in all mosaics. Preparation of the area by burning was most likely the determining factor in the differences in soil characteristics between forests and agricultural areas.

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The objective of this study was to verify the origin of and resulting floristic composition from seedbanks in different agroforestry systems in Tom e-Ac ßu, Brazil. The seedbanks were sampled in three smallholder farmers (Demonstration Units = DU), each with three agroforestry treatments and secondary forest as control. Seedling emergence in a glasshouse was used to quantify and identify the seeds collected in 2008. The floristic composition of the above-ground community was characterised with annual floristic surveys from 2008 to 2011. The total densities and diversity of the seedbanks were not different among the treatments within a given DU, but differences occurred among DU. The most abundant woody species had higher seed densities in the secondary forests than in DU. Conversely, among the herbaceous species, two groups were differentiated: species with similar densities between the DU and the secondary forest and species with higher density in the DU. In the DU, the similarity between the floristic composition of the seedbank and the flora surveyed in 2008 was high, but decreased in subsequent years. The species present in the seedbank of agroforestry systems are highly influenced by the secondary forest, but provide little information about the floristic composition that will arise in the future.

O objetivo deste estudo foi avaliar as modificações de propriedades físicas das madeiras de três espécies tropicais de interesse comercial por tratamentos térmicos conduzidos com diferentes temperaturas e tempos de exposição ao calor. Amostras de madeira de Pouteria caimito, Protium altissimum e Jacaranda copaia foram submetidas a modificações térmicas a 180 e 240 °C, ambas por 1 e 2 h. Foram avaliadas redução de massa, densidade básica e contração volumétrica das madeiras. O tratamento de 2 h a 240 °C causou maior redução de massa para todas as espécies. Pouteria caimito e Protium altissimum não apresentaram diferença significativa na densidade básica e contração volumétrica entre os tratamentos térmicos. A redução de massa, que confirma a efetividade dos tratamentos térmicos, aliada à manutenção da densidade é básica, é benéfica para a qualidade das madeiras. Jacaranda copaia apresentou maior estabilidade dimensional, mas foi mais afetada pelas variações dos tratamentos com diminuição da densidade básica da madeira quando submetida a 180 ºC por 1 h e 240 ºC por 2 h. A secagem das madeiras não tratadas, assim como os tratamentos térmicos, diminui a capacidade de adsorção de água e o volume saturado, resultando em contrações volumétricas similares às das madeiras termicamente tratadas.   Palavras-chave: secagem da madeira; hornificação; densidade básica; contração volumétrica.   Basic density and dimensional stability of tropical woods modified by thermal treatments   ABSTRACT: This study aimed to evaluate the wood physical properties’ modifications from three commercially interesting tropical species by thermal treatments carried out with different temperatures and heat exposure times. Wood samples of Pouteria caimito, Protium altissimum, and Jacaranda copaia were submitted to thermal modifications at 180 and 240 °C, both for 1 and 2 h. The mass reduction, basic density, and volumetric contraction were evaluated. The treatment of 2 h at 240 °C caused the highest mass reduction for all species. Pouteria caimito and Protium altissimum did not significantly differ in basic density and volumetric contraction of wood among thermal treatments. The mass reduction, which confirms the effectiveness of thermal treatments, allied to the maintenance of basic density, benefits the wood quality. Jacaranda copaia showed the greatest dimensional stability, but it was the most affected species by the variations of thermal treatments with decreases in basic wood density when submitted to 180 ºC for 1 h and 240 ºC for 2 h. The drying of the samples, as well as the thermal treatments, may decrease the water adsorption and saturated volume, resulting in volumetric contractions similar to those of thermally treated samples. Keywords: wood drying; hornification; basic density; volumetric contraction.

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