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Forest restoration in post-open pit mining areas is complex and faces the challenge of "recreating" the soil under horizontal disruption, representing strong barriers to root growth. Hence, trenches (paths opened by digging) for planting are an alternative to improve root development conditions and plant growth. This study aimed to evaluate growth of six tree species planted in trenches under three treatments: Topsoil or control (CT), Sawdust (SD), and Cow manure (CM). The trenches (1 m in height and length by 40 m long) were filled with topsoil. In the 6-m space between trenches, two treatments were performed: soil covered and not covered by sawdust to test natural regeneration. Six tree species (250 individuals) in pits over trenches where mortality, mean annual increment in height (MAIHt,), diameter (MAIDSH), and crown area (MAICA) were assessed. Natural regeneration and litter stock were also evaluated. After 18 months, mortality was zero, except Byrsonima spicata with less than 5% in CT, SD, and CM. Clitoria fairchildiana, Tachigali vulgaris, and Croton matourensis showed highest MAIHt and MAIDSH, and C. fairchildiana presented the highest MAICA with no statistical differences among treatments. Sawdust coverage had no effects on litter amounts and on tree species from the natural regeneration. Herbs and grasses covered 45.5% and 57.2% of the soil with and without sawdust. Based on growth and mortality, C. fairchildiana, T. vulgaris, and C. matarensis can be recommended for initial restoration after kaolin mining. [ABSTRACT FROM AUTHOR]

Mining is one of the economic activities that most degrade ecosystems, and the rehabilitation of such environments in the Brazilian Amazon is still a challenge. The first step is to recover the soil quality for plant reestablishment. In this study was evaluated the effect of different organic fertilizers, supplementary to chemical fertilizers, on the physical and chemical attributes of a minesoil after kaolin mining in the Eastern Amazon, Brazil. Nine trenches measuring 1 m × 40 m and 1 m in depth were opened in a reconstructed area after kaolin mining. They were 6 m apart from each other and filled with topsoil from areas destined for new mine pits. Then 40 cm × 40 cm × 40 cm pits were opened along the trenches. They were 1.5 m apart from each other within each trench, and 400 g pit−1 of simple superphosphate, 130 g pit−1 of urea and 130 g pit−1 of potassium chloride were applied in five treatments: three treatments along the trenches, in the planting rows with; i) addition of topsoil; ii) sawdust; iii) cattle manure, and two treatments between the planting rows; iv) sawdust; and v) without sawdust. Two hundred and fifty seedlings of six heliophilous tree species were planted, being randomly distributed. One hundred and forty-four disturbed (original structure altered) and 144 undisturbed (structure equal to the original soil) samples were collected for evaluation of the physical and chemical attributes of minesoil. Besides soil, other variables were assessed: plants abundance, height, diameter at breast height as well as litter stock. The treatments did not differ significantly in relation to the effects on abundance, height, diameter and litter stock, either in the planting rows or between them. The organic matter was higher in the Manure treatment at depths of 0.0–0.1 and 0.2–0.4 m. The sawdust coverage between trenches increased Ca and base saturation, but decreased N due to the high Carbon/Nitrogen ratio. Planting using trenches, topsoil, chemical and organic fertilization and sawdust coverage resulted in good physical and chemical properties of the soil and enabled greater efficiency in restoring the area mined for kaolin in the Amazon. • Trenches favored the planted and naturally established tree and shrub species. • Supplementary organic fertilization had not effect on the tree species development. • Sawdust coverage increased nutrient availability and reduced soil acidity. • Tree species in initial planting achieved rapid growth and high litter production. [ABSTRACT FROM AUTHOR]