The region of Murcia, located in the southeast of Spain, has historically been affected by deforestation and desertification processes that favour natural risks, sometimes ending in tragic personal consequences. To address this, at the end of the 19th century an ambitious plan was launched to reforest the mountains in the most problematic river basins. This article aims to study the changes experienced in the geographic mountain system “Carrascoy y El Valle” after reforestation, and their effects on different environmental processes. Two areas were selected to compare the evolution of the tree cover, using photographs from 1928 and current satellite images, and small grids were designed to analyze the current herbaceous and shrub cover. The results show a significant increase in tree cover in parallel to the mulch cover, which was higher in the shady than in the sunny orientation. The distribution of the herbaceous and shrub cover was irregular and unexpectedly higher in the sunny than in the shady areas, probably due to intensive trampling in the shady areas. Overall, the evolution of the geographic system “Carrascoy y El Valle” has been sustainable, with favourable effects on the ecosystem, erosion, landscape, and climate conditions, thus slowing down desertification.