RESUMOO presente estudo teve como objetivo avaliar os aspectos ecológicos e sucessionais de um fragmento de floresta subtropical via projeção da estrutura diamétrica de diferentes grupos ecológicos com uso da Matriz de Transição. Com base em medições de 2009 e 2012 de todas as árvores acima de 10 cm de DAP, foram realizadas projeções da distribuição diamétrica, bem como análise da dinâmica de três agrupamentos de espécies: Pioneiras; Não Pioneiras; e Floresta como um todo. Simulações da dinâmica dos agrupamentos foram feitas até 2027 após validação do método. O método de projeção se mostrou aderente em todos os casos, apresentando maior precisão quando utilizado o intervalo de classe de 5 cm. As análises indicaram tendência de substituição gradual das espécies pioneiras, sugerindo avanço sucessional no fragmento florestal estudado, bem como eficiência do método para análise da dinâmica dos grupos ecológicos estudados.Palavras-chave: dinâmica florestal, sucessão florestal, cadeia de Markov. Diametric Distribution Projection of Ecological Groups in a Mixed Tropical Forest ABSTRACTThis study aimed to evaluate the ecological and successional aspects of a subtropical forest fragment by projection of the diameter distribution of different ecological groups, using transition matrix model. Based on measurements of 2009 and 2012 of all trees above 10 cm of DBH, projection of the diameter distribution as well as analysis of forest dynamic were made for three species groups: Pioneer; Non Pioneers, and the whole forest. Simulations of the dynamics of the groups were made until 2027 after method validation. The projection method was adherent in all cases, with higher precision when using the 5cm class interval. The analysis made indicated a gradual substitution tendency of the pioneer species, suggesting a successional advance in the forest fragment under study, as well as an efficiency of the projection method for dynamics analysis of the ecological groups studied.

O objetivo desta pesquisa foi caracterizar parametricamente a fitossociologia de uma floresta ecotonal de 120 hectares, situada na região norte matogrossense, bem como testar a acuracidade de processos, frações amostrais e métodos estimativos para oito grupos de espécies. Estudou-se a composição florística e sua diversidade, distribuição espacial de espécies e características da estrutura horizontal para árvores com DAP ≥ 30 cm. Os processos aplicados foram aleatório e sistemático, com 5 e 10% de fração amostral, com 22 tamanhos e formas de parcelas variando de 400 a 10.000 m2. Identificaram-se 7.968 árvores distribuídas em 70 espécies (6 não identificadas), 58 gêneros e 31 famílias botânicas, apresentando, em média, 66,4 árvores e 11,08 m2 de área basal por hectare. A família botânica mais rica foi Fabaceae - Caesalpinioideae, e a mais frequente, Sapotaceae. A espécie mais importante foi Micropholis guyanensis (A. DC.) Pierre subsp. guyanensis. O padrão preponderante de distribuição das espécies é o aleatório nas parcelas de 400 m2 e agregado nas de 10.000 m2. Parcelas de 400 até 2.500 m2 estimaram com eficiência os valores de cobertura (VC) para o grupo das 15 espécies de maiores valores de importância (VI) e para as 6 comerciais mais importantes. Para os demais grupos de espécies, os erros mostram que os processos de amostragem aleatório e sistemático são inviáveis nas intensidades amostrais de 5 e 10%.

National Forest Inventories are important primary data sources for large-scale forest resource surveys, in which volume estimates of sampled trees are essential for quantitative analysis. Volume prediction models in natural forests are scarce in Brazil due to legal restrictions for cutting trees, especially in the Atlantic Forest. This study aimed to fit volume models for the main forest types and timber species of the Atlantic Forest in Rio de Janeiro state, considering two hypotheses: (I) generic volume models provide greater generalizability of estimates; however, (II) they may reduce the accuracy of forest typeand species-specific predictions. Four linear models with logarithmic transformation of variables were evaluated to fit volume models for generic and specific datasets, which correspond to the main forest types and timber species. Goodness-of-fit statistics were calculated to compare the accuracy and efficiency of the models, and selected models were validated through leave-oneout cross-validation procedures. The estimates obtained by generic and specific models were compared by non-parametric hypothesis tests. Generic models showed similar predictions to the specific models for forest types and timber species, with similar potential for stem and total volume predictions. Therefore, generic models can be used for Atlantic Forests in Rio de Janeiro state, while specific models are recommended to obtain more detailed local estimates.

The knowledge of the environmental variable seffect on the distribution of tree species is of great importance, since it contributes to a greater efficiency on the management of forests and on the conservation of degraded areas. In order to identify these effects on native species from the western region of Paraná, 21 plots of 2,000 m2 were installed in the Iguaçu National Park. The plots were distributed along the altitude gradient, between 150 and 750 m, and in different positions of the drainage ramps, from the river banks to the plateau regions. After the data processing carried out by Canonical Correspondence Analysis, it was identified species that are distributed in the vegetation according to the variations of altitude, humidity, fertility, saturation by aluminum and soil clay content. Some species presented tolerance to the environmental variations, a typical characteristic of species of wide geographic occurrence.

Bracatinga (Mimosa scabrella Bentham) is an important pioneer tree species in Ombrophylous MixedForest of Brazil and is widely used as an energy source. In traditional agroforestry systems, regeneration is induced by fi re, then pure and dense stands known as bracatinga stands (bracatingais) are formed. In the fi rst year, annual crops are intercalated with the seedlings. At that time the seedlings are thinned, then the stands remain at a fallow period and cut at seven years old. The species is very important mainly for small landowners. We studied the understory species that occur naturally during the succession over several years in order to manage them rationally in the future and maintain the natural vegetation over time. Three to 20 year-old Bracatinga stands were sampled between 1998 and 2011. All tree species with diameter at breast height (DBH) ≥ 5 cm were measured.The fl oristic evolution was assessed with respect to Sociability Index, the Shannon Diversity Index and the Pielou Evenness Index. Graphs of rank/abundance over different age groups were evaluated using the Kolmogorov-Smirnov test. We identifi ed 153 species dispersed throughout the understory and tend to become aggregated over time.