Complementing seedling planting with nucleation techniques increases forest restoration potential in areas around bauxite mining

Abstract

The soil seed bank is one of the most important ecological indicators to evaluate and monitor the ecological restoration process of plant communities. We aimed to analyze the influence of two different ecological restoration techniques on the diversity and floristic composition of the soil seed bank and of standing vegetation, in two 4-year-old areas under forest restoration around bauxite mining, Southeast Brazil. A total of 30 soil samples were collected in each area (SPN—forest restoration by seedling planting in rows and nucleation techniques between planting rows and SP—forest restoration by seedling planting in rows). The samples were transported to a shade house and evaluated for 6 months, where germinated individuals were counted and identified weekly. A floristic census of shrub/tree species was conducted to assess the diversity of standing vegetation. The results indicated that the soil seed banks of the two areas are floristically similar (predominance of pioneer, herbaceous, and native origin species). The two restoration techniques did not differ in their effects on the species composition of the soil seed bank, mainly due to the restoration age. However, when analyzing the standing vegetation, 38 species were recorded in SPN, while only 20 species were in SP. This result demonstrates that nucleation techniques contributed to the increase in species diversity in SPN. We conclude that combining seedling planting in rows with nucleation techniques (topsoil transposition, direct seeding, and artificial perches) can enhance species diversity in standing vegetation, improve forest functionality, and consequently enhance the potential for forest restoration.