This study investigated the vegetation and environmental variable of fragments at different successional stages in a secondary riparian forest in the municipality of Ponte Alta, Santa Catarina state, Brazil (27°29'00" S and 50°17'11" W, WGS84), aiming to list priority variables for monitoring forest succession in riparian forests. For this, two areas were identified: "Reference" (conserved secondary forest) and "Restoration" (secondary forest under passive restoration). The Principal Component Analysis (PCA) indicated the existence of differences in the arboreal community diversity with lower values for the "Restoration" synthesized by PC1. The ground coverage by Ocellochloa rudis (Nees) Zuloaga & Morrone (Poaceae) was mainly in places with higher pH values and ability for effective cation exchange, with no preference of occurrence in either evaluated site. The composition of arboreal diversity was a relevant variable for monitoring passive restoration in this environment.

Monitoring successional advancement is a complex field involving a constant search for applied ecological indicators which facilitate monitoring of secondary forests for both active and passive restoration. In this study, the authors investigate the successional advancement of floristics and tree structure within Araucaria Forest (AF) fragments under passive restoration in a context where exotic tree plantations (mainly Pinus L. genus) dominate the landscape. The ecological indicators used were floristic dissimilarity (β-diversity inferences), indicator species, ecological groups of species, basal area, and species abundance distribution (SAD) models (α-diversity inferences). A total of 182 tree species belonging to 91 genera and 43 botanical families were identified. A high β diversity was verified for which each site has indicator species (for the locations CD-Dicksonia sellowiana; CO-Cryptocarya aschersoniana; and PG-Pinus taeda), where pioneer species contributed to much of the abundance. Different SAD models are useful for describing passive restoration sites in exotic tree plantation landscapes, namely Lognormal, Mandelbrot, and Zipf. SAD models together with basal area, taxonomic group (e.g. Myrtaceae assemblage), and tree abundance in ecological groups are strategic ecological indicators for monitoring successional advancement in AF.

Pioneer species have the potential to colonize disturbed environments, contributing to the establishment of other species and driving the dynamics and advancement of the structure of forest communities. The aim of this study was to assess the evolution of floristic-structural composition in the regenerating stratum of communities formed in the Mimosa scabrella Benth. understory with different ages. The study was carried out in four municipalities located in the Santa Catarina State South Plateau, on communities with different successional ages. The plot method was applied to the survey of all arboreal individuals with height ≥ 10 cm. The floristic-structural patterns found were compatible with the expected trend of Araucaria Forest successional dynamic, showing higher richness and abundance of regenerating individuals in the older understories.

Ilex paraguariensis A. St. Hil. (yerba mate) is a native species widely consumed in southern Brazil, a region that presents a current scenario of forest fragmentation. The objective was to evaluate the genetic diversity, genetic structure, and gene flow among cohorts of I. paraguariensis in two forest remnants. Genetic analyses were conducted using microsatellite markers from leaves from adult (Ad), regenerating (Reg), and seed-derived (Se) populations in Santa Catarina (SC) (ChapecÃ’s National Forest [CCO]) and Rio Grande do Sul (RS) (Teixeira Soares’ Municipal Natural Park [PTS]). We found unique alleles in both populations, eleven in the CCO and eight in the PTS. There was no significant difference in genetic diversity indexes, whereas high and significant fixation indexes were observed (FCCO = 0.394; FPTS = 0.319). The proportion of genetic variation obtained between populations was lower (8%) than the proportion within populations (92%). The presence of significant genetic structure was verified in the cohorts of I. paraguariensis for two study areas. Moreover, all pairwise genetic divergence between Ad and Reg, and Ad and Se cohorts was significant, except for Ad versus Reg in PTS. Aiming to maintain diversity over generations, we recommend the conservation of remnants and expansion of connectivity between fragments. Study Implications Ilex paraguariensis is a species of high consumption and of social, cultural, and economic importance in southern Brazil. It occurs naturally or was naturalized in highly fragmented forests, which may reduce genetic diversity. The genetic analyses of different cohorts of I. paraguariensis reveals the current status of the genetic diversity of the species and indicates how diversity is maintained over generations. Thus, the study provides information for its use and conservation, maintaining genetic diversity.

ResumoA dinâmica das populações de plantas em uma c omunidade explica as mudanças qualitativas e quantitativas que ocorrem na vegetação, em que o balanço entre o recrutamento e mortalidade determina o funcionamento e a complexidade local, contribuindo para o entendimento das relações entre população e o meio. Objetivou-se avaliar alterações na estrutura populacional de Mimosa scabrella Benth., quanto ao recrutamento, a mortalidade e o incremento em área basal em populações com diferentes idades e verificar suas relações com variáveis ambientais. As populações avaliadas estão inseridas no Planalto Sul Catarinense, sob os domínios da Floresta Ombrófila Mista Montana (FOM-M) e Alto-Montana (FOM-A). No ano de 2012, três parcelas permanentes (40x40 m) foram aleatoriamente alocadas em populações naturais, onde todos os indivíduos presentes foram mensurados quanto o diâmetro a altura do peito para adultos (DAP ≥ 5 cm) e diâmetro a altura do colo (DAC) para regenerantes (DAP < 5 cm), os quais foram remedidos no ano seguinte (2013). Para todas as populações foram avaliados o total de indivíduos, mortalidade, recrutamento e alterações na densidade, assim como a influência das variáveis ambientais (química do solo, declividade e abertura do dossel) sobre os valores de incremento em área basal (m 2 ha -1 ). As alterações sobre a distribuição diamétrica caracterizam o caráter pioneiro de Mimosa scabrella, evidenciando o efeito da cobertura do dossel na dinâmica destas populações. Características relacionadas às maiores altitudes (FOM-A) alteraram o comportamento da espécie, influenciando os processos de dinâmica, especialmente a mortalidade, que apresentou taxa média de 10,5%. Mesmo não sendo fatores limitantes para o desenvolvimento de Mimosa scabrella, a mesma apresenta resposta em termos de crescimento sob condições de fertilidade. Palavras-chave: Mimosa scabrella Benth.; distribuição diamétrica; mortalidade; área basal; heterogeneidade ambiental. Abstract Dynamic Mimosa scabrella Benth. populations of different ages under different environmental conditions in the SouthernPlateau of Santa Catarina. The dynamics of plant populations in a community explains the qualitative and quantitative changes that occur in the vegetation, where the balance between recruitment and mortality determines the local functioning and complexity, contributing to the understanding of the relationships between population and the environment. The objective was to evaluate changes in population structure of Mimosa scabrella, as the recruitment, mortality and increase in basal area in populations with different ages and verify its relationship with environmental factors. The populations evaluated are embedded in Plateau of Santa Catarina, in the Montane Araucaria Forest (FOM-M) and Highland Araucaria Forest (FOM-A). In 2012, three plots (40 x 40 m) were randomly allocated into natural populations, where all individuals present were measured as the diameter of the breast height for adults (DBH ≥ 5 cm) and diameter neck height for regenerating (DNH < ...