RESUMO -(Anatomia do lenho de oito espécies de lianas da família Leguminosae ocorrentes na Floresta Atlântica). Lianas são importantes componentes estruturais das florestas tropicais, apesar disso a anatomia destes vegetais é pouco estudada. A família Leguminosae é relatada como a segunda maior em número de espécies de lianas, contudo pouco se conhece da diversidade anatômica das lianas desta família. O presente estudo descreveu e analisou a anatomia do lenho de oito espécies de lianas da família Leguminosae, ocorrentes no Parque Nacional do Itatiaia, localizado no Estado do Rio de Janeiro, região Sudeste do Brasil, local inserido no bioma Floresta Atlântica. As espécies apresentaram características comuns ao hábito liana, como: elementos de vaso com diâmetro elevado, com duas categorias de diâmetro; e maior proporção de parênquima axial em comparação às fibras. Quatro espécies do gênero Senegalia apresentaram variações cambiais produzidas por um único câmbio, normal em produto mas anormal em conformação. A anatomia do lenho das espécies estudadas é muito semelhante por compartilharem o mesmo hábito e pertencerem à mesma família. Apesar disso, as oito espécies estudadas puderam ser diferenciadas. As espécies com variações cambiais e Dalbergia frutescens são facilmente diferenciadas das demais. Contudo Senegalia tenuifolia, Piptadenia micracantha e Piptadenia adiantoides necessitam ser examinadas com muita cautela para identificá-las exclusivamente pela anatomia do lenho. Palavras-chave: anatomia da madeira, lianas, Mata Atlântica, LeguminosaeABSTRACT -(Wood anatomy of eight liana species of Leguminosae family from Atlantic Rain Forest). Lianas are important structural component of tropical forests and even though the anatomy of these plants is poorly studied. Leguminosae family is reported as the second larger family in number of liana species, but little is know about the anatomical diversity of lianas from this family. The present study described and analyzed the wood anatomy of eight liana species of Leguminosae family, from Parque Nacional do Itatiaia, located in Rio de Janeiro State, Southeast region of Brazil and included in Atlantic Rain Forest Biome. The species show common features with the liana habit, as: wide vessels, vessel dimorphism, and high proportion of parenchyma when compared with fibers. Four species of Senegalia genus showed cambial variants made by a single cambium, normal in products but abnormal in conformation. The studied species have similar wood anatomy, many of which are because they belong to the same family and share the same habit. Nevertheless, the eight species studied could be distinguished. The species with cambial variants and Dalbergia frutescens are easy distinguished from the others. However Senegalia tenuifolia, Piptadenia micracantha and Piptadenia adiantoides require much wariness examination to identify the species exclusively by wood anatomical features.

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Information about plant growth, development and age forms the basis for understanding complex forest ecological processes. Although lianas play an important role in tropical forests, little is known about their growth and development from either climatic or ecological perspectives. Therefore, we studied the growth rings in Legume liana species collected in a mountainous Atlantic Forest in southeastern Brazil. Four of the eight studied species did not show cambial variants, three had a lobed stem, and one had a furrowed xylem. Distinct growth rings were observed in all species. Semi-ring porosity, marginal parenchyma, fibrous zone and radially flattened latewood cells were the main characteristic features of these growth rings. Species without cambial variants, including Dalbergia frutescens, Piptadenia adiantoides, P. micracantha and Senegalia tenuifolia, showed very distinct growth rings visible in macroscopic and microscopic analysis. Ring-width time series and cambial wound assessment were performed to analyze periodicity and dendrochronology. The species with cambial variants, S. grandistipula, S. lacerans, S. martiusiana and S. pedicellata, also showed distinct growth rings, however, sometimes barely detectable or not detected at all. Cambial wounding, cross-dating and climate-growth relationships indicated the annual nature of growth rings in species without cambial variant. Crossdating between radii within one individual and between individuals was successful, and the synchronized series enabled us to build species chronologies and a mean chronology. Climate-growth analysis revealed significant correlations between chronologies and precipitation, indicating that available moisture is the main factor determining growth rates of lianas in the Atlantic forest.

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In this work we explore the radiocarbon (14C) signal as an independent tool to assess the year of formation of individual tree rings of tropical species in northern Brazil. Three different species were analyzed in this work: Dipteryx magnifica, Enterolobium maximum, and Hymenolobium petraeum. The studied samples are from the stem of only one individual of each species, all cut down in 2008 in Porto Trombetas, Pará, Brazil. Individual tree rings were identified based on wood anatomy and they were counted from bark to pith. Several rings were selected for 14C analysis in order to cover the overall shape of the 14C atmospheric bomb peak (after 1955). The 14C content was measured at Laboratory of Radiocarbon, Universidade Federal Fluminense (LAC-UFF). Results are compared with the Southern Hemisphere 14C atmospheric calibration curves. For E. maximum and H. petraeum the 14C signal exhibits an overall good match with the SH zone 3 and suggests annual seasonality in the growth-ring formation. These species offer suitable characteristics for dendrochronology. The D. magnifica shows mismatches in the 14C measurements that are likely a result of difficulties in identifying ring boundaries with certainty. Additional techniques may be helpful to disentangle the origin of this discrepancy.

Fire disturbance affects the composition, structure and dynamics of vegetation. Historical records of fire events exist in some places, but they are generally limited in temporal and spatial extent. Tree-ring research is a useful tool for fire history reconstruction and can contribute important long-term ecological data. We tested the hypotheses that Moquiniastrum polymorphum (Less.) G. Sancho, a widespread species in Brazil that occurs in burnt areas of Atlantic Forest, produces annual growth rings and that its wood can record fire incidence by datable fire scaring. Our results corroborate these hypotheses and indicate that the species has potential for fire history reconstruction.

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Sapindaceae lianas are remarkable for the diversity of cambial variants found in their stems. One of the family’s exclusive cambial variant is the divided vascular cylinder, which occurs in eight species of the genus Serjania. This cambial variant is marked by 5 peripheral vascular cylinders around a large pith. We performed a comparative developmental analysis, integrating traditional plant anatomy techniques with high-resolution X-ray micro-computed tomography to investigate the structure and development of the stems of three species with divided vascular cylinder. Our observations showed that the initial stages of stem development were similar to those described in the literature, however, on later developmental stages a central vascular cylinder appears in all species. The ontogeny of these stems are marked by three main processes: (i) dissection of vascular tissue from the peripheral vascular cylinders; (ii) development of new cambial arcs through the redifferentiation of pith cells; and (iii) recruitment of cambial cells from the inner portions of the vascular cambium of the peripheral vascular cylinders, forming a novel central vascular cylinder where the pith was, surrounded by five initial peripheral cylinders. As an ulterior developmental stage, some older stems also develop neoformations and connections between the different vascular cylinders. While our findings support previous descriptions of divided vascular cylinders, this is the first study illustrating the formation of the central vascular cylinder in this cambial variant. Our observations further corroborate that Serjania is the lineage with the highest and some of the most complex forms of cambial variants among all vascular plants.