Fluxos de cátions em ecossistema sucessaonal de floresta na região do médio Apeú, nordeste do Pará, Amazônia Oriental

Abstract

The valued ofthe influence of imgation and remova! of Htter on. the vatiatfoa m Etter was held at the Fish Culture in Freshwater (EPAD) in the municipalíty of Castantel (IoW S, 47057' W) during the period from January to December 2000 and 2006, wtth the aim of understanding the behavior ofCa and Mg in Htter in a forest ecosystem succession. This study was part of Project Handling of Water and Nutrients on Ecosystem. of Secondary Forest m Bastem Amazônia (MANFLORA). The experimental, design was- randomrzed; bloefcs with. 4 blocks with 3 replicates and 3 treatments-,, which were: control:, imgated (added 5 mm ofwater per day, for about 30 min. During the dry season) and remova! of Htter (held every 15 days. the total removal of Htter from. the soil surface). The seasonal production of Htter was well established, with occurrence of greaíer production of Htter in the months with lower precipitation. The total monthly Htter varied during the experimentai period from- 316..,10) te 997.90 kg ha"1mo'1, with an average of610.20 kg ha 'mo ^ aecording to. the fíoristic. síructure, represented by the species dominant Myreiasylvatica (G. mey) DC., Myreia bmeteata (Rich) DC., Miconia ciliata (Rich) DC, Lacistemapubescem Mart., Lacistema aggregatnm (Berg.) Rusby, Vismia guianensis (Aubl.) Choisy, Cupania scrobiculata Rich. and Ocotea guianensis Aubl, which constituted the determining factors associated with, the phenomenon hydroperiod. The analytical results obíained from monthly average mass of Ca ranging from 0.02 to 0.08 g rafW1, and Mg 0.006 to 0.03 g m'2mo'1, was sígniTicantly (P <0.0-5) different, so that the values of Ca were higher than Mg. The dynamics of Ca and Mg in the ecosystem with removal of the Htter were signifieantly (P <0.05) lower than those of control and irrigated treatments.