Flux of nutrients in rainfall and throughfall in the Tapajós National Forest, Belterra, Pará

Abstract

The rainfall is an important source of nutrients to ecosystems, especially in Tropical forest, which is extremely dependent on this source for their survival. The objective of this research was to quantify the of potassium (K+), phosphorus (P), calcium (Ca2+), magnesium (Mg2+) and iron (Fe2+) flux present in the direct precipitation (PD) and throughfall (PI) and also to verify the influence of the edge effect on the chemical composition of PI. The study was conducted in the Tapajós National Forest (FLONA Tapajós), in Belterra town, Pará, in the zone of influence of highway BR-163 (Santarém-Cuiabá), in two areas, km 67 and km 126. For the realization of the sampling outlined a transect, from the edge up to 100 m inside the forest, where the collections of PI occurred on the edges of the FLONA and PD in the respective surrounding areas. Only at km 67, also, were considered the flows of present nutrients in the PI, in FLONA Tapajós center. The nutrients flow, in general, showed the decreasing order: K+>Ca2+>Mg2+>P>Fe2+. It was possible to verify that the PI is an important source for potassium and that large-scale agriculture activities influence significantly the chemical composition of PI, in the zone of the plateau and FLONA Tapajós.