Among the consequences of the current dynamics of manmade land use and cover, forest fragmentation results in a large number of isolated fragments of different sizes. Forest provides many environmental services such as carbon sequestration and storage in the form of biomass, demonstrating the crucial role of native forests and the need to develop new methods that estimate forest biomass and carbon by non-destructive methods. This work aimed to develop a methodology to study and estimate the dynamics of forest biomass and carbon stock in successive stages of regeneration in the northwestern region of Rio Grande do Sul, which was the study area. Yearly images from 1985 to 2014 of the Normalized Difference Vegetation Index -NDVI were calculated, and a global regression was archived to obtain the leaf area index (LAI) and estimate the forest biomass. It was possible to observe the good relationship between the increase in LAI as a function of the NDVI, estimating the forest biomass of 61,156 Gg in 2014, where 602 Gg correspond to the initial regeneration stage, 8,287 Gg for the medium stage, and 52,267 Gg for the advanced stage of regeneration. The total estimated carbon for the study area in 2014 was 27,520 Gg CO2 of which 271 Gg were present in the initial stage, 3,729 Gg in the medium stage, and 23,520 Gg in the advanced stage of regeneration.