Calcium and Magnesium Dynamics in Litter in a Successional Forest Ecosystem, Under Hydroperiod

This study was part of the Manipulation of Moisture and Nutrient Availability in Young Regrowth Forests in Eastern Amazonia Project (MANFLORA). The experiment was designed in completely randomized blocks containing control and irrigated treatments during the dry period (5 mm of water/day), with four repetitions each. The monthly mean litter values ranged from 316.10 to 997.90 kg ha-1 month-1. The magnitude of this phenomenon can be explained by the functional role of the floristic structure, represented by the species Myrcia sylvatica (G. mey) DC., Myrcia bracteata (Rich) DC., Miconia ciliata (Rich) DC., Lacistema pubescens Mart., Lacistema aggregatum (Berg.) Rusby, Vismia guianensis (Aubl.) Choisy, Cupania scrobiculata Rich. and Ocotea guianensis Aubl., which constituted the determinant factors, associated with the hydroperiodic effect and ecosystem manipulation. The monthly mean of the analytical results of mass treatments were significant (P < 0.05), however, when compared annually there was no significance, which indicates seasonal influence, since the period of greatest deposition is the dry one, regardless of the water manipulation along the period studied. Only in time the mass values of Ca and Mg were not significant for treatment (P < 0.05). The amount of Ca was significantly (P < 0.05) higher than that of Mg.