ABSTRACT We present a summary of floristic variation and distribution of richness of tree and tree-like taxa (i.e., freestanding plants that reach at least 3m in height) in Brazil. We investigated composition patterns throughout phytogeographic domains and vegetation types based on 698,490 occurrence records obtained from the NeoTropTree (NTT) database, and used rarefaction and extrapolation methods to compare species richness. We delimited areas of high taxa richness in Brazil by applying the Geographic Interpolation of Endemism method. There are 9,108 tree species catalogued in NTT for Brazil, but our extrapolations indicate that the total could reach 9,525 species. Predominantly forested domains showed the greatest richness of taxa with the Amazon domain having the highest number of exclusive taxa. Fabaceae and Myrtaceae were the most represented families. The richest vegetation types were Rain Evergreen Forest and Seasonally Semideciduous Forest. Distribution patterns of richness in Brazil and among its domains were found to be controlled by different spatial scales for each taxon. Transition zones had high species richness. The patterns found here can help to identify priority areas for biodiversity conservation in Brazil.

Resumo Apresentamos uma revisão das visões controversas acerca da classificação fisionômica da Floresta de Linhares, aqui definida como a floresta sobre tabuleiros costeiros que ocorre entre os rios Doce e Barra Seca, no norte do Espírito Santo. Compilamos informações sobre o clima estacional dessa região e analisamos a inter-relação das variações interanuais e da dinâmica sazonal da precipitação com atributos ecológicos da floresta. Nossas interpretações revelaram que dados mensais médios de precipitação não exprimem a realidade dos períodos biologicamente secos ano a ano e suas consequências sobre a fisionomia da vegetação. Percebemos que a Floresta de Linhares pode se manifestar como semidecídua ou perenifólia, a depender da severidade da seca em um dado período. Então, propomos que a flexibilidade do regime de renovação foliar da Floresta de Linhares deve ser considerada em sua classificação. Sugerimos classificar a floresta duplamente como estacional semidecidual nos períodos anuais ou supra-anuais caracterizados por deficit hídrico pronunciado, e como floresta estacional perenifólia nos períodos anuais ou supra-anuais sem deficit hídrico significativo.

Abstract We present a review of the controversial points of view concerning the physiognomic classification of Linhares Forest, which is defined here as the forest over coastal tablelands that is found between the Rio Doce and the Rio Barra Seca, in the north of Espírito Santo. We compiled information about the seasonal climate of such region and analyzed the relationship of both the interannual variation and the seasonality of the rainfall with the ecological attributes of the forest. Our interpretations unveiled that the average monthly rainfall does not express the reality of the biologically dry periods year after year nor does it express the consequences on the vegetation physiognomy. We perceived that Linhares Forest may manifest itself as semideciduous or evergreen, depending on the drought severity within a given period. Thus, we propose that the flexibility of Linhares Forest leaf flush regime must be considered in its classification. We suggest a double classification for the forest: one as a seasonal semideciduous forest during annual or supra-annual periods that are characterized by pronounced water deficit and the other as a seasonal evergreen forest during annual or supra-annual periods with no significant water deficit.

ABSTRACT This study aimed to compare the spatial and the height distribution of three plant species between two rupestrian field communities, one preserved (A) and the other cultivated (B). One 50 × 100 m plot was delimited in each community and the populations of Eremanthus incanus, Lychnophora pinaster and Vellozia caruncularis were assessed for height and spatial distribution (using the Ripleys’s L-function). In community A, 4,098 individuals were counted, mostly L. pinaster, against 220 individuals in community B, prevailing E. incanus. An inverted-J pattern was observed for height distribution in both communities, however, with lower frequencies in B. Regular spatial distribution was found for E. incanus and V. caruncularis in community A, whereas the pattern for L. pinaster depended on the scale of analysis. The spatial distribution of all species differed between communities. The Ecological Park Quedas do Rio Bonito contributes to the conservation of these rupestrian field species.

Neste trabalho, objetivou-se descrever a dinâmica estrutural da comunidade arbórea de um fragmento de floresta semideciduifólia (Mata do Capivari), situado em Lavras, Minas Gerais. O estudo teve como base três inventários realizados no período de onze anos (1997, 2003 e 2008) em 28 parcelas permanentes de 20×20 m onde foi registrada a espécie e a medida de diâmetro à altura do peito (DAP) das árvores com DAP ≥ 5 cm, incluindo sobreviventes, mortas ou recrutas. A hipótese foi de que os padrões de dinâmica do primeiro período (1997 a 2003) persistiram no segundo (2003 a 2008). Os descritores da dinâmica foram taxas de mortalidade e recrutamento de árvores individuais (dinâmica demográfica), taxas de ganho e perda de área basal (dinâmica da biomassa) e as respectivas taxas de mudança líquida. Entre 2003 e 2008, a taxa de mortalidade, de 3,30%.ano-1, superou a de recrutamento, de 2,78%.ano-1. A taxa de ganho em área basal foi de 2,72%.ano-1, pouco inferior à de perda, de 2,98%.ano-1. De maneira geral, os padrões repetiram os do primeiro período (1998 a 2003), com persistência de um lento declínio demográfico, particularmente concentrado nas proximidades do rio, e uma área basal próxima da estabilidade, ao contrário da alta encosta, onde ocorreu uma significativa expansão. Comparativamente, a Mata do Capivari é uma das mais estáveis entre as estudadas na região, a despeito da persistente interferência humana

The present contribution aimed at describing the structural dynamics of the tree community of a forest fragment of seasonal semi-deciduous forest (Mata do Capivari) situated in Lavras, Minas Gerais State, South-eastern Brazil. The study was based on three surveys carried out during an 11-year period (1997, 2003 and 2008) in 28 20×20 m permanent plots where records were made of the species and diameter at breast height (dbh) of trees with dbh ≥ 5 cm, including survival, mortality and recruits. The hypothesis was that the patterns of dynamics found in the first interval (1997-2003) persisted in the second (2003-2008). The descriptors of dynamics were the rates of mortality and recruitment of individual trees (dynamics of demography), rates of gain and loss of tree basal area (dynamics of biomass), and respective net change rates. Between 2003 and 2008, the mortality rate, of 3.30%.yr-1, surpassed the recruitment rate, of 2.78%.yr-1. The gain rate in basal area was 2.72%.yr-1, only a little inferior to the loss rate, of 2.98%.yr-1. In general, these patterns repeated those of the first interval (1998-2003), with a persisting slow demographic decline, particularly concentrated near the river, and a nearly stable basal area. Comparatively speaking, the Mata do Capivari is one of the most stable among those studied in the region despite persistent human interference.

Accurate knowledge of floristic composition is crucial when planning and designing research projects and public policies. In this study, our goal was to assess tree sampling accuracy and to identify sites with higher concentrations of rare tree species, as well as those with the highest tree species richness, in the state of Santa Catarina, Brazil. We determined sampling accuracy using the first-order jackknife and Chao 2 estimators, calculated the number of rare species (singletons and doubletons) and applied sampled-based rarefaction. We found that sample accuracy (estimated vs. observed values) was over 90% for the state as a whole, the best estimates having been obtained for the areas of rain forest (first-order jackknife: 91%; Chao 2: 95%). Of the tree species identified, 16.6% were considered rare in the state and only 4% were found in all forest types. Among the various forest types, semideciduous forests showed the highest proportions of rare tree species. Tree species richness was highest in the rain forests and lowest in the dwarf cloud forests. Our results make an important contribution to the conservation of tree species within one of the "hottest" biodiversity hotspots in the world.

We analyzed the community structure of an upper montane cloud forest (elevation, 1900 m) in the Serra da Mantiqueira Mountain Range, in the state of Minas Gerais, Brazil. Our objective was to determine the comparative tree species richness and floristic diversity within this forest, which is at one of the higher elevations in the range, in relation to surrounding forests that are at lower elevations, adjusting for elevational gradients. Within 15 permanent plots (40 × 10 m each), we tagged all tree individuals with a diameter at breast height > 5 cm, registering their height and diameter. To compare the study area with neighboring cloud forests, we used the Sørensen similarity coefficient and phytosociological parameters. We sampled 1250 individuals distributed among 89 species, 55 genera, and 34 families. Canonical correspondence analysis revealed no gradients related to the vegetation or soil. We found that tree species richness and diversity were high in the study area. There was structural and floristic heterogeneity among the communities evaluated, underscoring the importance of conservation of these high-elevation ecosystems, which are so unique and irreplaceable.

Este trabalho apresenta o levantamento florístico das plantas vasculares da Reserva Biológica da Represa do Grama, um remanescente de floresta estacional semidecidual do Domínio Atlântico, situado no município de Descoberto, Minas Gerais. Foram realizadas coletas quinzenais de material fértil entre agosto de 1999 e dezembro de 2004. Além do levantamento, fez-se a comparação da composição florística através de análises multivariadas de agrupamento com outras nove áreas (3 de floresta estacional e 6 de ombrófila), cujos levantamentos florísticos de angiospermas tiveram abordagem semelhante. Cada análise foi processada para o conjunto total das espécies e para oito hábitos: árvores (incluindo arvoretas), arbustos, trepadeiras (lenhosas e herbáceas), ervas terrícolas, ervas saxícolas, epífitas, hemiepífitas e parasitas. Na ReBio do Grama foram registradas 644 espécies de angiospermas, distribuídas em 370 gêneros e 100 famílias. Licófitas e samambaias estão representadas por 64 espécies, distribuídas em 37 gêneros e 16 famílias. Seis espécies de angiospermas foram descritas como novas para a ciência. Fabaceae (55 spp.) foi a família com maior riqueza específica, seguida de Rubiaceae (50 spp.), Melastomataceae (28 spp.), Bignoniaceae e Orchidaceae (27 spp. cada) e Myrtaceae (25 spp.). As análises multivariadas sugeriram que os gradientes longitudinais, latitudinais e altitudinais interferem de formas distintas sobre os padrões de riqueza dos diferentes hábitos. O número reduzido de espécies compartilhadas entre as áreas, associado com alta riqueza regionalizada de alguns hábitos demonstra a importância da conservação de fragmentos nas diferentes regiões geográficas da Floresta Atlântica como estratégia para maximizar a conservação da diversidade existente neste domínio fitogeográfico.

The vascular plants survey of a remnant of semideciduous seasonal forest in the Atlantic Forest Biome was carried out in the ReBio do Grama, municipality of Descoberto, Minas Gerais, through forthnightly trips to collect fertile specimens between August 1999 and December 2004. The angiosperms included 644 species distributed in 370 genera and 100 families, including 6 species new to science, while the lycophytes and ferns included 64 species in 37 genera and 16 families. Fabaceae (55 spp.) was the family with the highest number of species, followed by Rubiaceae (50 spp.), Melastomataceae (28 spp.), Bignoniaceae and Orchidaceae (27 spp. each) and Myrtaceae (25 spp.). Once the survey was concluded, a comparison between it and the floristic composition of other nine areas (3 of seasonal and 6 of dense ombrophilous forest) was performed through multivariate analysis. These 9 sites were chosen as their surveys also included all angiosperm habits rather than only woody plants. Each analysis was processed for the all habits and then for each one of the following 8 habits: trees (including treelets), shrubs, climbers (woody and herbaceous), ground-dwelling herbs, rupicolous herbs, epiphytes, hemiepiphytes, and parasites. Multivariate analysis suggested that the longitudinal, latitudinal and altitudinal gradients interfere in different ways over the species richness of diverse habits. The reduced number of species shared between areas, associated to the high regional richness of certain habits shows the importance of conserving forest fragments in different geographical areas of the Atlantic Forest in order to maximize the conservation of the biodiversity within this Domain.

Rigorous and well-defined criteria for the classification of vegetation constitute a prerequisite for effective biodiversity conservation strategies. In 2009, a new classification system was proposed for vegetation types in extra-Andean tropical and subtropical South America. The new system expanded upon the criteria established in the existing Brazilian Institute of Geography and Statistics classification system. Here, we attempted to determine whether the tree species composition of the formations within the Atlantic Forest Biome of Brazil is consistent with this new classification system. We compiled floristic surveys of 394 sites in southeastern Brazil (between 15º and 25ºS; and between the Atlantic coast and 55ºW). To assess the floristic consistency of the vegetation types, we performed non-metric multidimensional scaling (NMDS) ordination analysis, followed by multifactorial ANOVA. The vegetation types, especially in terms of their thermal regimes, elevational belts and top-tier vegetation categories, were consistently discriminated in the first NMDS axis, and all assessed attributes showed at least one significant difference in the second axis. As was expected on the basis of the theoretical background, we found that tree species composition, in the areas of Atlantic Forest studied, was highly consistent with the new system of classification. Our findings not only help solidify the position of this new classification system but also contribute to expanding the knowledge of the patterns and underlying driving forces of the distribution of vegetation in the region.

A maior parte dos estudos envolvendo as Florestas Tropicais Sazonalmente Secas aborda questões fitogeográficas e conexões florísticas deste bioma disjunto. Porém, pouco se conhece a respeito das características estruturais da FTSS. Devido a esta lacuna existente na literatura, buscamos descrever a estrutura de um fragmento remanescente de FTSS em uma área ecotonal entre domínio do Cerrado e da Caatinga. Ocorreram no estudo grande número de espécies arbóreas, 79, e altos valores para os índices de diversidade e equabilidade (3,6 nats/indivíduos e 0,83, respectivamente). A distribuição diamétrica para os indivíduos que apresentaram maiores valores de cobertura e para a comunidade não resultou em padrão de J-reverso, o que indica adaptações ecológicas ao stress hídrico adotadas em diferentes estratégias de crescimento. Não houve formação de grupos florísticos, já que a alta fertilidade do solo da área de estudo configura um ambiente homogêneo. A característica da área de estudo detectada através da estrutura, associada a dados edáficos, nos permitiu vislumbrar sua importância em termos de conservação e reforçar a importância de estudos com este enfoque nas FTSS.

Most studies on Seasonally Dry Tropical Forests (SDTFs) investigate phytogeographic patterns and floristic connections of this disjunct biome. However, little is known about the structural characteristics of SDTFs. We aimed to describe the structure of a SDTF in an ecotonal area between the Cerrado and Caatinga domains. In total, 79 tree species were recorded, and high values of Shannon diversity index (3.6 nats/individual) and equability (0.83) were observed. The diameter distribution for the species with higher cover values and for the entire community did not exhibit a reverse-J shaped distribution, which indicates the occurrence of different growth strategies and ecological adaptations to water stress. The results did not indicate the formation of floristic groups, as the high soil fertility in the study area results in a homogeneous environment. The structural characteristics of the study area associated with the soil composition highlight its importance for conservation and emphasize the need for community structure studies in SDTFs.

Although biological surveys and taxonomic revisions provide key information to ecological and evolutionary studies, there is a clear lack of floristic and phytogeographic studies of the mountainous regions of Brazil, which harbor some of the most threatened plant ecosystems on the planet. Myrtaceae has been reported to be one of the most important families in the upland areas of Brazil, as well as in the Atlantic Forest Domain. In this study, we investigated the floristic composition of Myrtaceae throughout the Espinhaço Mountain Range and adjacent highlands of central-eastern Brazil, testing the following hypotheses: floristic similarity increases with geographic proximity; and species distribution is affected by geoclimatic variables. We performed statistical analyses using a database containing records of 199 species in 19 areas and of their respective geoclimatic variables. We also performed ordination analysis using non-metric multidimensional scaling (NMDS), the first and second axes of which explained 69% and 78% of the variation, respectively. The NMDS analysis demonstrated that variations in the Myrtaceae flora are highly sensitive to geoclimatic variables and geographic proximity. The NMDS ordination also showed a predominantly south-north gradient, as did the cluster analysis. This gradient was highly correlated with variations in rainfall and temperature, which are also associated with the three domains that coincide with the Espinhaço Mountain Range.

A presença cada vez mais disseminada de organismos exóticos (muitos dos quais se tornam invasores) nas diferentes regiões do planeta levou ao surgimento de uma linha de pesquisa na ecologia voltada às invasões biológicas. E para permitir a comunicação entre autores também foi desenvolvido um arcabouço terminológico. Mas, apesar disso, a terminologia relativa às bioinvasões tem sido ignorada por boa parte dos botânicos no Brasil. Há uma boa dose de confusão entre botânicos sobre o que seja uma espécie exótica, naturalizada, invasora, daninha e ruderal, levando ao uso inconsistente da terminologia. Além disso, diferentes autores têm adotado posturas praticamente opostas ao lidar com espécies exóticas em suas áreas de estudo, seja na preparação de tratamentos taxonômicos, seja na publicação de levantamentos florísticos e fitossociológicos. Enquanto alguns pesquisadores incluem em floras mesmo espécies cultivadas que não se reproduzem, outros excluem plantas invasoras comuns e conspícuas. Nós apresentamos aqui, em português, os principais conceitos relativos ao tema da bioinvasão e chamamos a atenção dos autores brasileiros para a necessidade de utilizar de modo consistente o arcabouço terminológico já existente na literatura. Também propomos a adoção de rótulos claros para informar quais espécies são exóticas na área estudada, diferenciando-as das nativas, e sugerimos critérios para ajudar botânicos a decidirem quando uma planta exótica deve ou não ser incluída em tratamentos taxonômicos ou levantamentos de florística.

The ever-growing presence of exotic organisms (many of which become invasive) throughout the planet has led to the emergence of biological invasions as a field of study within ecology. To enable communication between scientists in this field, a terminology has developed. However, this terminology has been ignored by many botanists in Brazil where there is confusion regarding definition of exotic, naturalized, invasive, weed and ruderal species, leading to inconsistent use of the concepts. Moreover, different authors have adopted antagonistic positions when dealing with exotic species existing in their study areas, either in the preparation of taxonomic treatments or in floristic and phytosociological surveys. While some authors include in floras cultivated, non reproducing species, others exclude even widespread and common invasives. We present here, in Portuguese, the main concepts related to the theme of bioinvasion and draw the attention of Brazilian authors to the necessity for consistent use of the terminological framework available for biological invasions. We also propose that authors should clearly label exotic plants reported in their work, differentiating exotics from native species. Finally, we suggest criteria to help botanists decide when exotic plants should or should not be included in taxonomic treatments or in floristic surveys.

Resumo A Serra Negra, no município de Rio Preto (MG), estende-se por uma região com fisionomias florestais serranas da Mantiqueira e campos altimontanos, entre as elevações do maciço do Itatiaia (RJ, SP e MG) e da Serra do Ibitipoca (MG). Com o objetivo de investigar o comportamento das variáveis comunitárias da flora arbórea em condições diferentes de altitude e alagamento, determinou-se a composição florística, estrutura e similaridade entre três fragmentos de floresta (aluvial, montana e nebular) e a suas relações florísticas com estudos da região. Foram amostrados 2.572 indivíduos, identificados em 194 espécies, distribuídas em 59 famílias e 118 gêneros. As famílias com maior riqueza foram Myrtaceae (30 espécies), Lauraceae (20), Melastomataceae (17) e Fabaceae (13). Os três tipos de vegetação estudados, associados a diferentes condições ambientais, diferem entre si em sua composição e estrutura. A floresta aluvial revelou-se com reduzida diversidade, baixa estatura e alta dominância ecológica. A floresta nebular destacou-se por apresentar elementos típicos de altitude em detrimento de espécies freqüentes na região abaixo da escarpa da serra, onde a diversidade foi maior. A flora arbórea da Serra Negra, formada pelo conjunto das áreas estudadas, apresenta um conjunto considerável de elementos com distribuição característica de ambientes montanhosos do Sudeste do Brasil.

Abstract Serra Negra is a region surrounded by some stretches of mountain, covered by Atlantic Forests and cloud scrubs, located in the southern part of Zona da Mata of Minas Gerais, in Serra da Mantiqueira, between the rises of the massif of Itatiaia (RJ, SP e MG) and the Serra do Ibitipoca (MG). The aim of this study was to determine the composition, structure and floristic similarity of arboreal flora among three forest types of Atlantic Forest (Alluvial, Montane and Cloud Forest) and also the similarity with other studies. A total of 2,572 individuals was sampled, from 194 species, 59 families and 118 genera. The highest number of species was recorded in the families Myrtaceae (30 morphospecies), Lauraceae (20), Melastomataceae (17) and Fabaceae (13). The three vegetation types associated with different environmental conditions differ in their composition and structure. The alluvial proved with low diversity and stature and high ecological dominance. The cloud forest stood out for its typical elements of altitude over other common species in the area below the range, where diversity was higher. The tree flora of Sierra Negra presents various indicator species to characteristic distribution of highlands of southeastern Brazil.

Devido à heterogeneidade fitofisionômica da vegetação na região Norte Mineira, a estrutura e riqueza de seus remanescentes são consideravelmente variáveis, e, embora pouco conhecida, trata-se de uma região amplamente explorada economicamente. Objetivou-se, com este estudo, caracterizar a estrutura e florística de uma área de caatinga arbórea, localizada em Juvenília, Minas Gerais. Foram alocadas 20 parcelas de 20 × 20 m (400 m²) totalizando 0,8 há. Nelas foram mensurados todos os indivíduos com CAP (circunferência à altura do peito) > 10 cm. Para complementar a listagem florística do componente arbustivoarbóreo, foram realizadas quatro visitas para coleta de material botânico entre janeiro e dezembro de 2003. A composição florística foi representada por 64 espécies arbóreas, destas, 47 foram amostradas no levantamento fitossociológico. A diversidade da área foi de H' = 2,90 e J' = 0,76, com dominância das espécies Anadenanthera colubrina, Poincianella pluviosa e Myracrodruon urundeuva que apresentaram os maiores valores de Dominância: 26,3, 13,1 e 20,3%; Densidade: 11,2, 16,6 e 10,1%; Frequência: 6,2, 6,5 e 5,5% e Valor de Importância: 14,6, 12,1 e 12,0%, respectivamente. A distribuição diamétrica da comunidade tendeu à normalidade, com menor quantidade de indivíduos nas classes diamétricas menores e maiores. A comunidade estudada mostra padrões estruturais e florísticos semelhantes a outros remanescentes de florestas deciduais em bom estado de conservação, dentro e fora do bioma Caatinga, embora tenha sido evidenciada a presença de interferências antrópicas na área.

Due to the phytophysiognomic heterogeneity of the northern Minas Gerais region, the structure and richness of local vegetation remnants vary considerably, and regardless of the fact that the region is yet little known, it has been widely explored economically. The objective of this study is to characterize the structure and floristics of a fragment of Arboreous Caatinga located in Juvenília, Minas Gerais. Twenty 20 × 20m plots (400 m²) were allocated, to a total of 0.8 ha, and all individuals in them with a CAP (circumference at breast height) > 10 cm were recorded. To complement the floristic listing of shrub and tree components, four visits were undertaken to collect botanical material, between January and December 2003. The floristic composition was represented by 64 arboreous species, out of which 47 were sampled in the phytosociological survey. The local diversity was H' = 2.90 and J' = 0.76, with a dominance of species Anadenanthera colubrina, Poincianella pluviosa and Myracrodruon urundeuva, respectively with Dominance: 26.3%, 13.1% and 20.3%; Density: 11.2%, 16.6% and 10.1%; Frequency: 6.2%, 6.5% and 5.5% and Importance Value: 14.6%, 12.1% and 12.0%. The diameter distribution of the community tended to normality, with less individuals in smaller and larger diameter classes. The structural and floristic patterns of the community in question were found to be similar to other reasonably preserved remnants of deciduous forest, inside and outside the Caatinga biome, despite the evidence of local anthropic intervention.

Resumo Os fragmentos de Mata Atlântica interioranos localizam-se em região de tensão ecológica e carecem de conhecimento sobre os efeitos de impactos antrópicos sobre sua composição e regeneração. Objetivou-se caracterizar e descrever a estrutura e composição da comunidade arbórea em remanescentes florestais localizados em Itumbiara, Goiás, além de analisar as relações florísticas entre esses e outros fragmentos de formações estacionais e de áreas ecotonais. Foram selecionados cinco fragmentos para a amostragem da comunidade arbórea. Foi aplicado o método de quadrantes, sendo alocados, em cada fragmento, transecções lineares contendo 25 pontos, o que resultou no estabelecimento de 125 unidades amostrais. Em cada ponto, foram inventariados os espécimes arbóreos vivos com circunferência a 1,30 m acima do solo >15 cm. As coletas florísticas e o levantamento fitossociológico registraram 149 espécies arbóreas, pertencentes a 110 gêneros e distribuídas em 47 famílias. A análise de similaridade demonstrou o caráter ecotonal, com muitas espécies generalistas e outras de ocorrência mais pontual no Cerrado ou em matas estacionais. Os remanescentes florestais em Itumbiara apresentaram elevada diversidade arbórea. No entanto, a comunidade arbórea sugere relações florísticas mais estreitas com as formações savânicas.

Abstract Hinterland fragments of Atlantic forests situated in transitional areas are poorly known with respect to the effectsof human impacts on their species composition and regeneration. The purpose of this study was to describe andcharacterize the structure and composition of the tree community of forest remnants located in Itumbiara, GoiásState, Central Brazil, and to analyze their floristic relationship with other areas of seasonal and transitionalvegetation ecotones. Five forest fragments were chosen for tree community sampling. The survey was carried outusing PCQ (point-centered quarter) method and 25 points were distributed along linear transects totalling 125sampling units. Four live trees with circumference at breast height (1.30 m) > 15 cm were recorded at each point.The floristic and phytosociological surveys recorded 149 tree species belonging to 110 genera and 47 families.The analysis of similarity confirmed the ecotonal character with many generalist species and other with occasionaloccurrence in 'Cerrado' (woody savanna) and seasonal forests. The forest remnants in Itumbiara showed a hightree species diversity. In spite of this, the tree community species suggests higher similarity with savanna vegetation.

Objetivando caracterizar possíveis flutuações nos padrões de distribuição diamétrica foram analisadas, num intervalo de cinco anos (2000-2005), a comunidade e as populações das 15 espécies mais abundantes do compartimento arbóreo de um remanescente de Floresta Semidecídua. A distribuição diamétrica da comunidade apresentou alta concentração nas classes menores e diminuição acentuada no sentido das maiores (J-invertido), em ambos os inventários. As populações apresentaram padrões distintos, arbitrariamente distribuídos em dois grupos: Grupo 1, formado por espécies de menor porte e abundantes no sub-bosque, como Galipea jasminiflora, Allophylus edulis, Sebastiania commersoniana, Dendropanax cuneatus e Mollinedia widgrenii, e também espécies de árvores altas e pioneiras, como Acacia polyphylla e Piptadenia gonoacantha, cujas distribuições diamétricas seguiram o modelo J-invertido. Com exceção de Calycorectes acutatus, todas as demais espécies do Grupo 2 (Platycyamus regnellii, Cupania vernalis, Machaerium stipitatum, Machaerium villosum, Copaifera langsdorffii, Persea major e Cassia ferruginea) eram de maior porte, cujos adultos predominavam no dossel da floresta, elevando a área basal e apresentando densidade de indivíduos menor nas classes diamétricas inferiores. No intervalo considerado, apenas D. cuneatus alterou seu padrão de distribuição (Grupo 1-Grupo 2), enquanto as demais os acentuaram. No Grupo 1, a síndrome de dispersão preferencial era anemocórica ou autocórica, ao passo que no Grupo 2 predominava a zoocoria. Assim, o remanescente, por apresentar área pequena, forma alongada e localização semiurbana associada a um regime de intensas perturbações, pode ter ocasionado empobrecimento da fauna dispersora, prejudicando a taxa de recrutamento.

Aiming to characterize possible fluctuations in the patterns of diametric distribution, the community and the populations of the 15 most abundant tree species in a fragment of semideciduous forest were analyzed in a five year interval (2000-2005). The diametric distribution of the community showed a high concentration in the smaller classes and accentuated reduction in the biggest classes (reverse-J-shape), for both surveys. The populations presented different patterns, randomly distributed in two groups. Group1, formed by species of smaller diameters and abundant in the sub-canopy, such as Galipea jasminiflora, Allophylus edulis, Sebastiania commersoniana, Dendropanax cuneatus and Mollinedia widgrenii, and also by pioneer species of high trees, Acacia polyphylla and Piptadenia gonoacantha followed the reverse-J-shape curve diametric distributions . All species of Group2 (Platycyamus regnellii, Cupania vernalis, Machaerium stipitatum, Machaerium villosum, Copaifera langsdorffii, Persea major and Cassia ferruginea) except Calycorectes acutatus, present bigger diameters, and their individual adults predominate in the forest canopy, increasing the basal area and presenting a density of smaller individuals in the lower diametric classes. In the evaluated interval, only D. cuneatus altered their distribution pattern (Group1-Group2), while the others increased. In Group1 the main dispersion syndrome is anemochory or autochory, while in Group2 the zoochory syndrome predominates. As the fragment presents a small area, elongated form and semi-urban location associated to a regime of intense disturbances, which may have caused a decrease of the fauna disperseres, compromising the recruitment rate.