Fitossociologia e propriedades físicas da liteira em ecossistema sucessional de floresta alterada na Amazônia Oriental

Abstract

The physical properties are analyzed to understand the role of litter in experimental manipulation regime in the successional ecosystem of forest (ESF). In this ecosystem, three treatments: CTL=Control, REM=Litter removal and IRR=Irrigation were evaluated. Thus, the question was: Is there a difference in magnitude of physical properties between treatments after 12 years?. And the hypothesis (h): If the manipulations of REM and IRR altered the metabolism of ecosystems, so in these biological systems there may have been differences in the physical properties of litter. Therefore, the objective was to evaluate the physical properties of litter 12 years after the end of the REM and IRR experiment. The study was carried out in the experimental plots of the MANFLORA Project, UFRA of Castanhal, northeastern Pará. Each treatment presented 4 plots of 20x20m and with the help of a metallic collector, 40 samples/treatment were collected during four months. Phytosociologic characterization (CAP>5) was performed in the treatments. The variables analyzed of physical properties were: litter storage (Mg ha-1), density (g cm-3), thickness (cm) and water retention capacity (%). The design used was fully causalized 3x4. The results of phytosociology showed more expressive values for Lacistema pubescens in the treatments CTL and REM, while Pourouma guianensis in the IRR treatment. In the ecological groups, CTL and IRR showed a predominance of secondary and pioneer species, while REM was secondary and climax, and these characteristics were the determining factors for understanding litter storage. The analyses of the magnitudes of mean values of the physical properties found that the hypothesis was accepted (ANOVA, p <0.05), that is, after 12 years of the end of the treatments there is still a difference between the treatments. In addition, there was the recovery and balance between REM and IRR, both with higher values, understanding that the effect of REM favored its ecological evolution.