The Iezer Mountains are part of the Southern Carpathians in Romania; the elevation range spans over 1800 m, with the highest peak at 2470 m. In recent years, the vegetation in this montane landscape has undergone various changes. The aim of the present analysis is to test whether the evolution of vegetation zones can be modeled using remote sensing data and official forestry cadastre data, in correlation with climatic data for the same period. Our analysis used the change detection procedure (image difference) with 2 LANDSAT TM/ETM subscenes for the summers of 1986 and 2002. Field research (2001–2005) helped us to validate thematic classification of the altitudinal zones. The change detection image showed general trends: an increase in timberline elevation, a gradual replacement of coniferous forests by mixed forests, and a natural regeneration of beech trees on mountain slopes.