Factors influencing early natural regeneration in areas under passive restoration in Araucaria Forest, southern Brazil

Abstract

Passive restoration is widely adopted in restoration areas previously used by pine plantations. However, little is known about which environmental factors influence the initial natural regeneration in these areas. Our objective was to relate environmental variables to the floristic-structural patterns of early natural regeneration in areas under passive restoration post-harvest of Pinus taeda. We related natural regeneration data with vegetation and soil variables obtained in 19 plots (100 m²). The ordering of the floristic-structural data of natural regeneration was carried out by NMDS (Non-Metric Multidimensional Scaling) analysis, and the significant variables (p < 0.05) were plotted a posteriori. The results indicate that soil conditions are adequate for natural regeneration development in the study areas. The variables pH, clay, and canopy cover showed a relationship with the floristic-structural composition of the initial natural regeneration. These findings indicated a gradient of texture and acidity and a successional gradient among the sites. In general, tree species show an association with sites containing high canopy cover and soils of greater acidity and clay content. On the other hand, pioneer-shrub species predominate in sites with low canopy cover and soils that are less clayey and acidic.