No abstract

The present study explored the influence of edaphic variables and forest leaf cover on natural regeneration in a remnant of a Mixed Ombrophilous Forest (MOF) in southern Brazil. Principal component analysis (PCA) was used to elucidate the heterogeneity of edaphic and leaf cover variables among the sampling units, and the variables exhibiting the strongest correlations with the sampling units were selected. Subsequently, these variables were used to explain floristic patterns using canonical correspondence analysis (CCA). In PCA, the leaf area index explained only some variation in the data, and there was obvious heterogeneity in edaphic variables among the sample units. In the main canonical axis of the CCA, Miconia cubatanensis, Myrcia multiflora, Casearia decandra, and Myrsine coriacea showed greater correlation with variables associated with soil acidity. In contrast, Allophylus guaraniticus and Cupania vernalis showed a high correlation with variables related to bases. Overall, the analysis of soil physicochemical characteristics can allow for the more precise identification of indicator species for the restoration of remnant of MOF in southern Brazil.

This study aimed to analyze the temporal changes in the floristic composition and regeneration structure in a remnant of Mixed Ombrophilous Forest that has been without interventions for decades. Two surveys were undertaken for the study; the first survey was conducted in 2012, and the second in 2017. The experimental area comprised 20 circular plots of 2.5 m radius, where was it performed the quantification of the regenerants, measurement of individual tree heights, and identification of the ecological group that each surveyed species belonged. All individuals with a minimum height of 0.50 m and a circumference at breast height of less than 15 cm were measured. Approximately 12,382 ind ha-1 were found in 2012 and 11,185 ind ha-1 in 2017. Only the following species increased their abundance per hectare in 2017 compared to the previous survey: Dalbergia frutescens (280.3 ind ha-1), Myrsine coriacea (178.3 ind ha-1), Allophylus guaraniticus (76.4 ind ha-1), Bernadia pulchella (51.0 ind ha-1), Casearia obliqua (50.9 ind ha-1), Casearia decandra (25.5 ind ha-1), and Luehea divaricata (25.5 ind ha-1).  The remaining species had a negative balance or disappeared from the study. Ecological group analysis indicated the gradual replacement of shadow-tolerant climax species by pioneer and light-demanding climax species. The most representative species identified on both occasions did not undergo major changes, indicating that they are more likely to remain in the studied area. The results indicated that the studied remnant forest is in an advanced phase of succession; however, it presents punctual alterations that reflect its floristic and ecological dynamics.