Landscape analysis based on soil color in the windward slope of the Baturité Massif, northeastern Brazil

The Baturité Massif is located in northern Ceará state (Northeast Brazil) and is the most humid mountain range of the state, with an average annual rainfall of 1500mm. The predominant lithostratigraphic unities are composed of gneisses, schists, quartzites, amphibolites, and other calcium-silicate rocks. The mountainous relief reaches 800-900 m a.s.l on the central region of the massif, which stands out by steep and winding slopes in contrast with vast flattened surfaces of 100 - 200 meters a.s.l. Based on previous studies in the area, this research aimed to analyze the correlation between the coloration of the Lixisols - the most common type of soil in the region, and the changes in size and density of the vegetation, featuring a tropical evergreen forest at the highest altitudes and a tropical semideciduous forest at low altitudes. In order to identify variations in soil color, a morphopedological analysis was carried out through toposequence in the municipality of Pacoti, located at the windward slope of the Baturité massif. Samples were collected in 6 soil profiles, with altitudes ranging from 300 to 950 meters. The determination of coloration was executed with the wet samples, using the Munsell chart and from the collected values, the soil redness index (RI) was calculated using the following equation: RI= ((10- M) × C)/V; M = hue (7.5R = 0; 10R = 1; 2.5YR = 2; 5YR = 3; 7.5YR = 4; 10YR = 5; 2.5YR = 6); V = value; C = chroma. Profile 1 (960 meters) presented low-density vegetation of arboreous size, with low RI on both superficial and sub superficial soil horizons. At intermediate altitudes (>400m and <600m), the soil profiles 2, 5 and M, presented vegetation in a climax state with low RI values on superficial horizons but high RI values on sub superficial horizons. On the other hand, at the lower altitude region (<400m), soil profiles 3 and 4 presented quite the opposite, with high RI values on the superficial horizons and low RI values at the sub superficial ones, the vegetation in this area was shrubby and with a high density of individuals. Thus, it is assumed that there is a direct correlation between reddening indexes, topography, and state of vegetational development of the landscape