Caracterização dos sítios experimentais do esecaflor (Caxiuanã-Pa)

Abstract

As a forest reserve, the Ferreira Penna Scientific Station (ECFPn) is a source of national and international research. In this context, several research projects are developed within the LBA project (Large Scale Atmosphere and Biomass Experiments in the Amazon). The Experiment on Drought in the Forest (ESECAFLOR) is researching the influence of soil water exclusion on the forest cycle. This experiment is in the phase of development and collection of preliminary data (soil, vegetation, climate ...). The objective of this paper is to present data from the soil characterization in the experimental plots. Two plots were separated with 1 ha each, in one of which the water exclusion will be done (plotl) and the other will be the control (plot2). The third plot is the atmospheric data collection tower (plot3). The samples were collected at five depths: (0-20cm), (20-40cm), (40-60cm), (60-80cm), (80-100cm). At field level, the soils were classified as belonging to the Latosols group, presenting a sequence of A, B, and C horizons. Coloration ranged from dark yellow bruno (lORY, 3/6) to yellowish red (7.5 YR, 6/6). The texture ranged from sandy to clayey, ranging from well (plotl and 2) to poorly drained (plot3). The samples were dried at room temperature and properly sieved on 2mm mesh. Subsequently, the humic substances were extracted and then the humic acids (HA) and fluicic acids (FA) were separated. After the separation of the organic matter fractions, they were ready to undergo characterization processes such as: soil pH and organic carbon (OC). The pH is moderately acidic with ranges from 4.6 to 5.0 (plotl), 4.9 to 5.3 (plot2) and 4.6 to 5.4 (plot3). Soil organic carbon ranged from 105.50g/Kg-la 3.9g/Kg-l(plotl), 13.4g/Kg-l to 3.3g/Kg-l(plot2) and 24.12g/Kg-l to 4.6g/Kg-l(plot3). The soil showed a high proportion of AF in relation to AH. In plot3 there was more accumulation of soil CO and higher contents of humic substances. This fact may probably be related to the drainage variation, the topography and the vegetation cover of the site, since the parent material is the same, sedimentary sandy rocks of the Alter do Chão Formation.