Estabelecimento inicial de aniba rosaeodora ducke em plantios comerciais sobre solo com variações texturais na Amazônia Central

Abstract

This study aimed to evaluate whether the initial development of Aniba rosaeodora - a species of great social, economic and environmental relevance in the Amazon - is influenced by soil texture along a topographic gradient.The work was carried out at Fazenda Simpatia, located at km 3 of Ramal da Sudam, on the right bank, municipality of ltacoatiara, Amazonas. Over the two hectares of Aniba rosaeodora plantation, the following characteristics were measured, in 10 plots, with 30 trees each: 1) Diameter of the collar, 1O cm above the ground, using a precision digital caliper (O, 01 mm); 2) Full height (AT) using a measuring tape; 3) lnsertion height (AI) of the crown using a measuring tape; 4) Diameter of the crown (DC) in the projections of the lines and between the lines using a measuring tape. From the crown height, crown projection height and crown diameter data, the crown length (CC) and crown volume (VC) were calculated. ln addition to dendrometric information, soil samples were collected in the center of each inventoried plot. ln each plot, samples were collected in the layers of O - 20 cm and 20 - 40 cm in depth, using the mini trench technique. Statistical analysis was obtained using the Pearson correlation coefficient. A small variation in altitude - 11.3 meters (54.68 - 43.39 m) - provided a significant variation in the clay and sand contents of the soil. The association between plot altitude and soil texture, in the two evaluated layers (0-20 cm and 20-40 cm), was proven by the correlation analysis, except for the silt values. lt was observed that as the altitude of the plot increased, the soil was more concentrated in clay and less concentrated in sand. Soils in plots with an altitude of less than 47.3 meters were mostly sandy in the O - 20 cm layer; while in plots with altitude above this limit, medium textured soils were observed in the O - 20 cm layer. ln the 20 - 40 cm layer, most of the sampled soils were of medium texture, with the exception of the plot at 43.39 meters of altitude where the soil was sandy; and the plot at 54.68 m where the texture in the subsurface layer was clayey. High mortality (>30%) and variation in growth among trees in the plantation were observed. Variation in tree growth was associated with soil texture along the topographic gradient; therefore, the dendrometric characteristics of the species were associated with the concentration of sand (greater growth) and clay (lower growth) in the superficial and subsuperficial layers of the soil. ln conclusion, the results show that the soil texture varies according to terrain altitude changes, positively influencing the initial establishment of Aniba rosaeodora planting in conditions of higher sand concentration in the lower parts of the topography in the region of the municipality of ltacoatiara.