Resumo Avaliou-se a dinâmica do componente arbóreo e regenerante em uma floresta nebular, na região do Planalto Sul Catarinense, com o objetivo de se conhecer o processo de desenvolvimento da vegetação ao longo do tempo. Para isso, foram instaladas parcelas permanentes onde foram caracterizados os componentes adulto e regenerante, respectivamente, nos anos de 2011 e 2013. Todas as espécies amostradas foram classificadas quanto à guilda de regeneração em pioneiras, climácicas exigentes em luz e climácicas tolerantes ao sombreamemto. No ano de 2015, foi realizado o segundo inventário dos componentes vegetacionais, sendo determinado o crescimento dos sobreviventes (somente adultos) e contabilizados os indivíduos recrutados e mortos. Para cada uma das populações, foram determinadas as taxas de mudança líquida em número de indivíduos (adultos e regenerantes) e em área basal (adultos). Foram realizados testes de proporções para verificar se a representatividade das diferentes guildas de regeneração se alterou entre os anos avaliados. Os resultados indicaram que a floresta se encontra em um processo de estruturação, caracterizado pelo ganho em número de indivíduos e em área basal. Por outro lado, observou-se estabilidade na riqueza e na representatividade das guildas de regeneração, com destaque para a maior participação de espécies classificadas como clímax exigentes em luz. Conclui-se que a floresta avaliada se encontra em estruturação, com o favorecimento da regeneração de espécies exigentes em luz.

Abstract The dynamics of adult and regenerative tree species components was assessed in a cloud forest in the South Plateau of Santa Catarina state, southern Brazil, seeking a better understanding of the process of vegetation development. To this end, permanent sampling plots were allocated, where the adult and regenerative components were characterized, respectively, in 2011 and 2013. All surveyed species were classified according to regeneration guilds into pioneer, light-demanding climax, and shade-tolerant climax. In 2015, a second tree species component survey was conducted to determine the growth of surviving individuals (adults) and count the recruited and dead individuals. For each population, the net change rates for individuals (adults and regenerative) and basal area (only adults) were determined. Proportion tests were conducted to verify whether representativeness of the regeneration guilds changed over the study period. The results showed that the forest investigated is undergoing a structuring process characterized by gains in number of individuals and basal area. In contrast, stability in species richness and representativeness of regeneration guilds was verified, with highlight for light-demanding climax species. In conclusion, the assessed forest is undergoing a structuring phase that favors the regeneration of light-demanding species.

Resumo O presente estudo objetivou analisar a dinâmica do componente arbóreo em floresta com araucária em função da distância da borda, em Santa Catarina, Brasil. Foram realizados levantamentos da vegetação em 2011 e 2015, pelo método de parcelas permanentes, em cinco transeções contendo dez parcelas de 200 m2 cada, sendo as cinco primeiras parcelas (0-50 m) definidas como setor borda e as cinco últimas (50-100 m) como interior. Em 2011, os indivíduos arbóreos foram inventariados e em 2015 os sobreviventes e mortos foram quantificados e os recrutas incorporados ao levantamento. Foram calculadas as taxas de mortalidade e recrutamento e as espécies foram classificadas em guildas de regeneração. Os resultados demonstraram que a dinâmica da comunidade não diferiu entre os setores, porém as guildas de regeneração apresentaram diferentes performances em função da distância da borda, com espécies existentes em luz favorecidas na borda e espécies tolerantes ao sombreamento no interior. Conclui-se que a fragmentação florestal tem o potencial de impactar negativamente o componente arbóreo na floresta com araucária.

Abstract This study aimed to analyze the tree component dynamics in an araucaria forest in function of fragment edge distance in the Santa Catarina state, Brazil. To do so, we conducted the vegetation surveys in 2011 and 2015, through permanent plots, in five sampling transects, containing ten 200 m2 plots for each one. The first five plots (0-50 m) were defined as edge sector and the last five plots (50-100 m) were considered as interior sector. In 2011, tree individuals were surveyed, with the recruit and dead individuals counted in 2015. The rates of mortality and recruitment were determined, and the species were classified into regeneration guilds. The study showed that there was no difference in tree community dynamics between the analyzed sectors, but the regeneration guilds presented different performance in function of edge distance, with light-demanding species succeeding in edge and shade-tolerant species performing better in the interior. We conclude that forest fragmentation has the potential to impact negatively the tree component in Araucaria forest.

ABSTRACT: The natural regeneration process is essential for forest maintenance since it is critical for establishing new tree individuals. This study aimed to improve the understanding of the regenerative component dynamics of Araucaria Forests in Southern Brazil. We investigated the effects of climate, light, tree component structure and anthropogenic disturbance on tree species regeneration. Regenerating communities from six different fragments in forest remnants of the “Planalto Sul Catarinense” region was evaluated in permanent plots two years after the first inventory. The following demographic rates were determined: recruitment, mortality, net change in the number of individuals and the changes to both upper and lower height classes. The following variables were measured in each fragment: altitude, climatic variables, light environment, tree component density and cattle presence. Association between dynamics rates, regenerating species abundance and explanatory variables was verified by the fourth-corner and RLQ methods. A total of 4,379 and 5,268 individuals were sampled for the first and second inventories, respectively, with recruitment rate (21 % yr−1) higher than mortality rate (13 % yr−1). The dynamics pattern of the fragment with greater presence of cattle stood out for the intense height increase of regenerating species caused by the presence of fast growth and light-demanding species. Natural regeneration of forest remnants under study is facing a structuring process. The main conclusions of this study were: i) climate and altitude play a relevant role in defining floristic identity and ii) chronic disturbances may influence the definition of ecological strategies.

RESUMO Objetivou-se caracterizar a organização florístico-estrutural, a riqueza e a estrutura filogenética de comunidades arbóreas de fragmentos florestais altomontanos em diferentes estágios sucessionais, situados no Parque Nacional de São Joaquim em Urubici, Santa Catarina. Foram selecionados três fragmentos, dois em avançado estágio sucessional e um em estágio inicial, sendo cada um avaliado por meio de 20 parcelas de 10 x 10 m, distribuídas na forma de transecção de 20 x 100 m. Foram identificados e medidos todos os indivíduos arbóreos com DAP ≥ 5 cm. Os dados foram analisados por meio de rarefação, ordenação multivariada, análise de espécies indicadoras e métricas de estruturação filogenética. A riqueza encontrada em cada fragmento não apresentou relação com o estágio sucessional, uma vez que as áreas não difeririam quanto a este aspecto. A organização florístico-estrutural foi influenciada pela interação entre o estágio sucessional e as diferenças ambientais entre os locais. Na área em início de sucessão, foi observado o agrupamento filogenético das espécies, e nas áreas tardias, o padrão foi aleatório. Assim, os resultados evidenciaram variações na riqueza independentemente do estágio sucessional e que a sucessão florestal influenciou a composição florístico-estrutural e a estrutura filogenética das áreas.

ABSTRACT We aimed to describe the floristic-structural organization, the richness and the phylogenetic structure of tree components in highland forest fragments in different successional stages, at São Joaquim National Park, in the municipality of Urubici, Santa Catarina state. Three fragments were selected, two in an advanced successional stage and one in an initial successional stage, being each one evaluated by 20 10 x 10 m sampling plots, allocated as 20 x 100 m transects. All trees with dbh ≥ 5 cm were identified and measured. The data were analyzed through rarefaction, multivariate ordination, indicator species analysis and phylogenetic structure metrics. There was no relationship between the richness and the successional stage, once the studied areas did not differ in relation to the number of species. The floristic-structural organization was influenced by the interaction between the successional stage and the environmental differences among areas. Phylogenetic clustering of species was observed in the initial successional stage area and random phylogenetic pattern was observed in advanced successional stage areas. The results indicated independent variation in richness in relation to successional phase and, that the forest succession influenced the floristic-structural composition and phylogenetic structure of the study areas.

RESUMO O presente estudo teve como objetivo investigar o impacto do enchimento do reservatório de uma usina hidrelétrica sobre as taxas de dinâmica do componente arbóreo em uma floresta adjacente. Para isso, foram alocadas 48 parcelas em três setores do fragmento: adjacente às margens do reservatório, meio da encosta e topo da encosta. Um ano após o enchimento do reservatório, todos os indivíduos arbóreos com circunferência a altura do peito (CAP) ≥ 15,7 cm foram avaliados (identificados e mensurados), e dois anos após o enchimento foi realizado o estudo de dinâmica, com as árvores sobreviventes remedidas, as mortas quantificadas e as recrutas incorporadas. Foi realizado o levantamento das variáveis ambientais edáficas, topográficas, de abertura do dossel e de impacto ambiental. Foram calculadas as taxas de dinâmica. Para ordenação das variáveis ambientais foi aplicada uma Análise de Componentes Principais (PCA) e a influência de gradientes ambientais sobre as taxas demográficas da comunidade foi verificada por meio de regressão logística. A dinâmica apresentou estabilidade no número de indivíduos, porém, com maior ganho (3,64%.ano-1) que perda (1,62%.ano-1) em área basal. Entre os setores houve distinções, sendo o setor 1 caracterizado pela maior taxa de perda em área basal (2,51%.ano-1). Houve pouca relação das taxas demográficas com as variáveis ambientais analisadas, indicando que a maior influência encontrada sobre o crescimento das árvores está associada a variáveis não mensuradas. O presente estudo indica que, dois anos após o enchimento do reservatório, foi possível perceber os primeiros efeitos da influência do lago da hidrelétrica na comunidade arbórea.

ABSTRACT We aimed to investigate the impact of the water reservoir of a hydroelectric power station on the tree component dynamics in an adjacent forest. For this, we allocated 48 plots in three sectors: bottom, adjacent to water reservoir, middle slope and upper slope. One year after the water filling, we measured (circumference at breast height - cbh and identified all trees with cbh) ≥ 15,7 cm, followed by the dynamics study in the next year, with the re-measurement of survival trees and quantification of mortality and recruitment. We evaluated environmental variables (edaphics, topographics and environmental impacts). We determined the dynamics rates and applied a Principal Component Analysis (PCA) to the ordination of environmental variables and analyzed the influence of environmental gradients on community demographics rates through logistic regression. The dynamics presented number of individuals stability, but a greater basal area gain (3.64%.year-1) than loss (1.62%.year-1). There were differences among sectors, with a greater loss in bottom sector (2.51%.year-1) than others. There was a weak relation between analyzed environmental variables, suggesting that trees growth is mostly related to non-measured variables. The present study indicates that, two years after the water filling, it is possible to detect the short-term impacts of the reservoir of hydroelectric power station on tree community.

SUMMARY: This study aimed at analyzing the dynamics of tree components in a forest adjacent to the Barra Grande Hydroelectric Power Plant reservoir, in the southern Brazilian Atlantic Forest, located in the municipality of Capão Alto. In 2013, this area was previously inventoried and divided into three sectors according to the distance from the reservoir: lower sector (in contact with the reservoir), intermediate sector (a slope area following the first sector) and upper sector (near the slope top). Fifty plots were allocated in the sectors, where all tree individuals with DBH (diameter at breast height) higher than or equal to 5 cm were inventoried (identified and measured at the circumference). In 2017 the surviving individuals were measured again, the dead ones were registered and the recruits (those with DBH reaching 5 cm) were included into the survey. Dynamics rates in number of individuals and basal area were calculated. The tree community under study has shown species richness stability, though also structural development, which is typical of areas that are facing a self-thinning process. The higher density populations of each sector have shown a similar structural dynamics pattern. There were no differences in the demographic rates among sectors, indicating that, approximately 12 years after the reservoir filling, the forest dynamics has not been influenced by the reservoir but by ecological factors dependent on density, such as competition.

RESUMEN: El objetivo del estudio fue analizar la dinámica del componente arbóreo en un bosque adyacente al reservorio de la Usina Hidroeléctrica (UHE) Barra Grande en Capão Alto, Mata Atlántica del sur de Brasil. En el año 2013, se hizo un inventario en el área, y se dividió en tres sitios con diferentes distancias del embalse: sector inferior, en contacto con el embalse; sector intermedio, área de ladera tras el primer sector, y sector superior, cerca de la cima. Fueron espaciadas 50 parcelas en los sitios, donde todos los individuos arbóreos con clase diamétrica (DAP) igual o mayor a 5 cm fueron inventariados (se identificaron y se midieron sus circunferencias). En 2017, los individuos sobrevivientes fueron remedidos, los individuos muertos registrados, y los de reclutamiento (aquellos que alcanzaron 5 cm de DAP), agregados al estudio. Se calcularon las tasas de dinámica en número de individuos y en área basal. La comunidad presentó estabilidad en la riqueza de especies y desarrollo estructural, típico de áreas que se encuentran en proceso de autorraleo. Las poblaciones de mayor densidad y de cada sector presentaron patrón de dinámica estructural similar. No se observaron diferencias en las tasas demográficas entre los sitios, por lo tanto, se concluye que, aproximadamente 12 años después del llenado del embalse, el mismo no está influenciando la dinámica del bosque adyacente, siendo esta más influenciada por factores ecológicos dependientes de la densidad, como la competencia.

ABSTRACT The aim of the present study was to characterize the floristic-structural heterogeneity of the tree species in an alluvial forest remnant considering three sectors: forest-river edge, forest interior and forest/non-forest matrix edge. Forty-eight plots of 200 m 2 were allocated and all tree individuals with a diameter at breast height (dbh) equal to or greater than 5 cm were measured and identified. Data was analyzed by Shannon’s diversity index, Pielou evenness and phytosociological descriptors. Plots were ordered through NMDS. Sixty-six species were sampled and Myrtaceae was found to be the richest family. Diversity and evenness reached 2.96 and 0.71, respectively. Sebastiania commersoniana (Baill.) L.B.Sm. & Downs presented the highest importance value (21.22%). The NMDS showed that tree components are spatially partitioned according to sectors, therefore indicating floristic-structural heterogeneity.