Abstrait

Seasonal patterns of nitrogen and phosphorus in the litter and soil surface of transitional Amazon cerrado forest, Brazil

Luciana Sanches, Eliane Dias de Almeida, Osvaldo Borges Pinto Junior, Jose de Souza Nogueira

Measurements of litter production, and the surface litter pool were made over a 1 year period in a tropical transitional forest near Sinop,Mato Grosso Brazil with the aim of quantifying the seasonal variation of nitrogen and phosphorus in the litter and the annual contribution of nutrients to the soil. Average annual litterfall (+95% confidence interval (CI)) was 8.20 ton ha-1 year-1 and forest floor litter mass was 58.63 ton ha-1. Nitrogen and phosphorus in the forest floor litter mass was highest during the dry and dry-wet season, being 38% higher than in the wet and wet-dry season. Seasonal variation in the litter and concentration of nutrients was explained by seasonal variations in the climate, for example in the precipition and soil humidity. Average annual nitrogen and phosphorus concentrations in the forest floor mass were 17.24 ton ha-1 and 16.46 ton ha-1, respectively. The more significant forest floor mass fraction for returning soil nutrients was the leaves. The concentration of nutrients was higher in the soil superficial layer (at depths between 0-5cm) than at depths between 30-70 cm, approximately 83% and 93% for total nitrogen and available phosphorus, respectively.