In recent years, anthropogenic actions have intensified forest fragmentation, causing several damages to the landscape’s natural components, such as the loss of biodiversity. This study aims to present a space-time analysis of the forest fragments found in a conservation unit located in southern Brazil. An evaluation of the fragments’ spatial pattern was carried out for the years 1998, 2008 and 2018, by using landscape metrics. Classification of remote sensing imagery of the Landsat satellite were applied to generate land use cover maps. The following metrics were analyzed: area and edge, shape, core area, and aggregation. The results indicated an increase of 16.88% in the total area of vegetation. As a consequence, the percentage of fragments in the landscape increased from 16.16% to 18.89%. The number of fragments decreased by 2257 due to their union, which resulted in an increase of the mean area by 5.4 ha and an increase by 0.103 of the irregularity of the spots measured by the average shape index. The percentage of vegetation under border effect changed from 40.2% to 37.1%. Isolation between fragments showed a decrease over the analyzed period. In 1998, the average Euclidean nearest neighbor distance was 155.4 m, and in 2018, 149.7 m. However, this distance is still classified as a high degree of isolation, which hinders the movement of organisms and the dispersion of species. Thus, all the analyzed metrics indicated a decrease in the fragmentation, except for the edge density metric, in which its increase by 1.86 pointed to a lower degree of conservation during the analyzed period. A study of this nature is important since it provides subsidies for future research on the management of forest fragments and can contribute to adopting action strategies in the management plan of the area.