Could past land uses, and the land cover changes carried out, affect the current landscape capacity to maintain biodiversity? If so, knowledge of historical landscapes and their socio-ecological transitions would be useful for sustainable land use planning. We constructed a GIS dataset in 10 × 10 km UTM cells of the province of Barcelona (Catalonia, Spain) for 1956 and 2009 with the changing levels of farming disturbance exerted through the human appropriation of photosynthetic net primary production (HANPP), and a set of landscape ecology metrics to assess the impacts of the corresponding land-use changes. Then, we correlated them with the spatial distribution of total species richness (including vascular plants, amphibians, reptiles, birds and mammals). The results allow us to characterize the main trends in changing landscape patterns and processes, and explore whether a land-use legacy of many complex agroforest mosaics maintained by the intermediate farming disturbance managed in 1956 could still exist, despite the decrease or disappearance of those mosaics before 2009 due to the combined impacts of agroindustrial intensification (meaning higher HANPP levels), forest transition (meaning lower HANPP levels) and urban sprawl. Statistical analysis reveals a positive impact of the number of larger, less disturbed forest patches, where many protected natural sites have been created in 1956-2009. However, it also confirms that this result has not only been driven by conservation policies and that the distribution of species richness is currently correlated with the maintenance of intermediate levels of HANPP. This suggests that both land-sharing and land-sparing approaches to biodiversity conservation may have played a synergistic role owing to the legacy of complex land cover mosaics of former agricultural landscapes that are now under a serious threat.