A conservação florestal em área da antiga colônia agrícola nacional de Goiás, norte do Mato Grosso de Goiás

Abstract

From the 1930s, motivated by a set of factors that favored the expansion of the agricultural and demographic frontier in Goiás, the occupation and consequent deforestation of the tropical forest region known as Mato Grosso de Goiás (MGG) occurred. This area had been kept out of the advance of colonization in Central Brazil since the 18th century. However, with the "March to the West" Policy, and more strongly after the 1940s, with the creation of the Goiás National Agricultural Colony (CANG) the process of deforestation and change in landscapes and land use intensified. In this occasion, this project aimed to relate the changes in the landscape of the old CANG delimitation, in a historical series, correlating with the regional anthropic activities, verifying if the conservation and the management of the forest resources deferred to the Cerrado Biome are applied in the region, considering the peculiarity of the soil and vegetation. In order to do so, we seek to base ourselves on the theoretical and methodological assumptions of environmental history and apply the following investigation procedures: bibliographical research, forest inventory, soil analysis and historic mapping. In the forest inventory data were collected in 15 sample transects, with a record of 312 individuals, on average 20.8 individuals per transect. The 312 individuals are distributed in 99 identified species and in 37 botanical families. 18 families presented only one species each. 14 individuals were only identified at the family level, and 11 were not identified. The Fabaceae family was the most representative. The Diameter at Breast Height (DBH) of greater expressiveness in individuals was <7.96, being Hirtella glandulosa Spreng. the most representative species; and the lowest DBH of <30.25. The height of the species varied from two meters for individuals in the sub-forest, up to 20 meters and fifty centimeters for emerging canopy species such as Cariniana estrellensis (Raddi) Kuntze and Apuleia leiocarpa (Vogel) JF Macbr. from four to five meters and ninety-nine centimeters. From 1946 to 2018, many changes occurred in the soil. In the analysis of 2018 the Ca, Mg, Al, H + Al, MO, C and CTC levels are higher in soils with vegetation, indicating a higher conservation of these soils. In the pastures, the levels of K, P and SATB are higher, and may be a reflection of the chemical fertilization in the area and of the leaching processes. Despite the good results, the years 1946 to 1948 showed much higher rates. The pH presented elevation of a forest soil, in 1946 from weakly alkaline to in 2018 as strongly acid. And in AD, from weak acid to strongly acid. The maps of land use and land cover yielded overall accuracy and Kappa coefficient greater than 80% for all classified images. Agriculture, forestry, burning and exposed land had a reduction from 1985 to 2018, with the greatest reduction being the exposed soil class, while the water, pasture and urbanization classes increased, with pastures being the most exponential.