Phytosociology and physical properties of the litter in an altered successional ecosystem in the eastern Amazon

Abstract

This study aimed to evaluate the physical properties of the litter and the phytosociology of a successional forest, 12 years after the end of the experiment of manipulation of natural resources, submitted to three treatments: Control (CTL); Litter removal (REM) and Irrigation (IRR). We performed the phytosociological characterization (CAP>15 cm) and collected the litter stored in the soil in two periods (rainy and less rainy). The variables analyzed for the physical properties of the litter were the litter stock (Mg ha^-1), density (g cm^-3), thickness (cm) and the water retention capacity (%). Lacistema pubescens, Annona exsucca and Ocotea guianensis were found in all treatments. The CTL and IRR treatments showed the highest density of individuals and similarity. Shannon's index ranged from 1.71 to 2.13 but did not differ between treatments. The REM treatment presented the highest average values of stock in the rainy season (8.66 ± 0.42 Mg ha^-1), while in the less rainy period, treatments with resource manipulation were superior to the control. The water retention capacity was similar between treatments, however we found a slow process of ecological restoration, which can be justified by the proximity to urbanized areas. We believe that the removal of litter can delay the development of plants that are less tolerant of unfavorable soil conditions, but an stimulate the morphophysiological adaptations. Twelve years after the end of the treatments, we found that the manipulation of resources influenced the recovery of the physical properties of the litter, with few effects on the phytosociological characteristics.