Em toda região da Floresta Ombrófila Mista, parte do Bioma Mata Atlântica, o corte seletivo e pastoreio são atividades muito comuns. Com o objetivo de relacionar a composição e estrutura com o histórico de uso, foram avaliados os indivíduos arbóreos adultos e juvenis de 12 fragmentos em Santa Catarina. Os fragmentos com menor impacto antrópico apresentaram, para o estrato adulto, maior riqueza e amplitude diamétrica, e menor densidade e frequência de múltiplos fustes, apesar da área basal não diferir entre os fragmentos. Quanto ao estrato juvenil, os fragmentos com maior impacto apresentaram maior riqueza e menor densidade. Os resultados demonstram que o impacto antrópico sobre a comunidade arbórea foi de tal magnitude, que, mesmo passadas algumas décadas, diferenças florísticas e estruturais permanecem evidentes, com tendência a se manterem por longo período.

The present study aimed at sampling the biomass of vascular epiphytes within a protected area in South Brazilian Atlantic Forest. All tree specimens with diameter at breast height equal or greater than 4.8 cm were measured and divided into classes. In each class, 10% of tree specimens were randomly selected for epiphytic biomass measuring. Furthermore, we divided the phorophytes into five tree parts to analyze epiphytic biomass. We generated mathematical models to estimate epiphytic biomass in similar forest areas. We analyzed 55 phorophytes and found an estimated epiphytic biomass of 5.3 Mg/ha. Epiphytic biomass ranged from 0.02 to 135 kg and the lower values were found on small-sized phorophytes. Higher values of epiphytic biomass were found on phorophytes with diameter at breast height between 30 and 36.5 cm. The tree part with higher epiphytic biomass was the outer crown. The epiphytic biomass showed a high correlation with phorophyte diameter, according to the mathematical models. We selected two equations which presented the most similar values to the ones we measured. Our results corroborate that epiphytes play a very important role as to the biomass level within tropical forests.

Cyclones are an increasing disturbance in the subtropical region of South America, but their impacts over the forests are still poorly documented. Here, we evaluate the effects of an extratropical cyclone over tree mortality in Araucaria Forest remnants in southern Brazil. We surveyed 116 sites (10 × 20 m each) and collected data on all tree individuals presenting DBH ≥ 4.8 cm before (2009) and after (2014) the occurrence of an extratropical cyclone. Using GLM models, we checked how the cyclone occurrence, different plant traits (DBH, trunk branching, wood density, successional group and evolutionary distinctiveness) and site characteristics (basal area, exposure, landscape protection, nearest border distance, cyclone border distance and the presence of native bamboo species) could impact tree mortality. The GLM model selection shows that the lowest AIC model considers all predictors separately and their interaction with the cyclone. The results showed that the cyclone occurrence and some site characteristics (bamboo presence, site exposure, landscape protection, nearest border distance and cyclone border distance) and plant traits (successional group and evolutionary distinctiveness) are related to tree mortality. The intense deforestation and fragmentation of the Araucaria Forest coupled with the increase in cyclone frequency expected for the region due to climate change may increase mortality rates of these forests, affecting their resilience and phylogenetic structure. Further biodiversity conservation efforts in the Araucaria Forest need to consider the characteristics of sites for enabling the protection of forest remnants in areas under different exposures to cyclone impacts.