This study aimed to analyze relationships among the structure of the tree component, edaphic variables and canopy discontinuity along a toposequence in a seasonal upland (hillside) forest in southern Brazil. Soil and vegetation were sampled in 25 plots of 20 × 20 m each. We described the vegetation in terms of structure, richness and diversity, as well as by species distribution patterns. We evaluated canopy continuity, determined sloping and calculated spatial coordinates. We applied partial canonical correspondence analysis (pCCA) to determine whether species distribution correlated with environmental and spatial variables. We identified 1201 individuals belonging to 76 species within 30 families. The species with highest density and frequency were Gymnanthes concolor Spreng., Calyptranthes tricona D.Legrand, Eugenia moraviana O.Berg and Trichilia claussenii DC. The pCCAs indicated significant correlations with environmental and spatial variables. Sand content, boron content and soil density collectively explained 36.17% of the species matrix variation (total inertia), whereas the spatial variables x, y and xy 2 collectively explained 14.27%. The interaction between environmental and spatial variables explained nearly 4.5%. However, 45.05% remained unexplained, attributed to stochastic variation or unmeasured variables. Terrain morphology and canopy discontinuity had no apparent influence on richness, and changes in species distribution were correlated with sloping, which affects soil features and determines the directional distribution of some species. factors associated with topography, such as riparian forests along flood gradients Giehl & Jarenkow 2008) and hillside forests (Sühs & Budke 2011, Loregian et al. 2012. In general, studies have shown that most species have clustered spatial distribution, and that many generate dense clusters, decreasing the richness and abundance of other species in nearby areas. Sühs & Budke (2011) evaluated the distribution and association among tree species in a hillside forest, having observed greater association among species at more advanced successional stages and greater dissociation among species at distinct stages (for example, pioneer and shade-tolerant). These results highlight the role of biotic relationships, whereas relationships of facilitation and competition may often result in spatial patterns that are less dependent upon physical environment.Although these factors are extremely important on the community scale, on a regional scale, climatic factors have been identified as determinants of the distribution of plant species (Giehl & Jarenkow 2012). From this perspective, deciduous forests have been described as being strongly associated with the seasonality of precipitation and temperature This study aims to investigate the relationship between the distribution of tree species and spatial-environmental variables in a hillside forest situated on a moderate slope gradient (average slope of 25%) and that, therefore, could offer different establishment cond...

Regeneração de espécies arbóreas e relações com componente adulto em uma fl oresta estacional no vale do rio Uruguai, Brasil RESUMO (Regeneração de espécies arbóreas e relações com componente adulto em uma fl oresta estacional no vale do rio Uruguai, Brasil). O estudo de fenômenos relacionados às variações na estrutura das comunidades vegetais tem cada vez mais envolvido a avaliação do potencial de regeneração das espécies arbóreas, uma vez que a regeneração torna as fl orestas capazes de se restaurarem após distúrbios naturais ou antrópicos. Neste sentido, objetivou-se avaliar o componente arbóreo regenerante, identifi cando composição e abundância, grupos funcionais de dispersão, estratificação vertical e necessidades de luz para germinação, além de estimativas de riqueza e diversidade e comparar estes valores com o respectivo componente adulto. O levantamento foi realizado em 20 unidades amostrais de 10 x 10 m, sendo amostrados todos os indivíduos com altura ≥ 0,30 m e diâmetro a altura do solo ≤ 4,7 cm. O levantamento do componente adulto, avaliado em estudo anterior, foi estabelecido em unidades amostrais de 20 x 20 metros, sendo amostrados todos os indivíduos com diâmetro à altura do peito ≥ 4,7 cm. Foram amostrados 1.649 indivíduos em regeneração, pertencentes a 64 espécies, com densidade total estimada em 8.245 ind.ha -1. As espécies com maior densidade absoluta foram Gymnanthes concolor Spreng., Trichilia elegans A.Juss. e Calyptranthes tricona D.Legrand. Uma análise de coordenadas principais indicou nítida separação das unidades amostrais amostradas e um teste de Mantel revelou haver independência entre as matrizes de composição e abundância dos componentes adulto e regenerante (r = 0,19; p = 0,1). Dentre os grupos funcionais, verifi cou-se que o componente regenerante está mantendo as mesmas proporções observadas para o componente adulto, com maior proporção de espécies zoocóricas, dependentes de luz para germinação e formadoras do dossel fl orestal. Ao contrário do esperado, houve diminuição da riqueza no componente regenerante (p < 0,001) e manutenção da equabilidade ao longo da área. Palavras ABSTRACT(Tree regeneration and relationships with adult trees in a seasonal forest in the Uruguai river valley, Brazil). Studies related to variation in plant communities have been involved the analysis of regenerative potential of tree species, because saplings may enable forests to restore themselves aft er natural or human disturbances. Th e goal of this study was to analyze tree regeneration by identifying composition and abundance, the ecological groups of dispersion, vertical stratifi cation and light requirements for germination and to look for changes in expected richness, diversity and relationships with structure of adult trees. A sapling survey was conducted in 20 sample units of 10 x 10 m where all individual living trees were sampled that had a height ≥ 0.30 m and diameter at soil height ≤ 4.7 cm. Adult trees with a diameter at breast height ≥ 4.7 cm were surveyed in 20 x 20 m sampling units, acc...

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