Distribuição espacial de carbono em solo sob floresta primária na amazônia meridional

Abstract

The study of the carbon cycle is of great importance due to its intricate relationship with changes in the earth's climate. One of the relevant causes of changes in the carbon cycle is the high rate of land use change in the Amazon region, which replaces tropical forest cover with agriculture and grazing. This study was carried out in Juruena, Mato Grosso with objective of studying the spatial distribution of soil carbon concentrations and stocks (0-0.60 m) in headwater catchments under primary forest using geostatistical techniques. A total of 185 georeferenced sample points were established using a 20 x 20 m grid over four headwater catchments. Soil samples were collected from the 0-0.60 m depths at each point. The bulk density increased from 1.36 ± 0.08 g cm-3 (mean ± 1 SD) to 1.46 ± 0.083 g cm-3 for the 0-0.20 and 0.40-0.60 m depths, respectively. Soil carbon stocks (0-0,60 m) were distributed between the headwater catchments as: basin 1 = 56.73 t ha-1, basin 2 = 59.35 t ha-1, basin 3 = 59.22 t ha -1 and basin 4 = 64.35 t ha-1; with a mean for the entire study area of 59.74 ± 10.30 t ha-1. In spite of the apparent homogeneity of the visible landscape characteristics such as slope, soil color and vegetation, the carbon and soil clay attributes were found to vary greatly. This variability over small distances demonstrates that extrapolation of soil characteristics and soil carbon stocks to larger areas could produce erroneous results if the spatial variability of the soil attributes is not taken into consideration.