Using high-resolution multitemporal imagery to highlight severe land management changes in Mediterranean vineyards

Mediterranean vineyards are subjected to drastic changes due to socio-economic, physical and environmental drivers. Whereas global trends affecting the evolution of Mediterranean land cover are well-known, their descriptions at a fine spatial scale, i.e., a plot level of several decametres, and over long time periods are still underexplored. This lack of exploration persists despite the increase in multitemporal imagery at fine resolutions. As scale and stakeholders are often correlated, we hypothesize that monitoring land cover at fine spatial and temporal scale would help understanding the local drivers shaping landscapes. To that end, we exploited a database of aerial pictures to obtain classified and vectorized land uses at the field level during the past five decades of a large watershed. The land uses were analyzed to detect changes at the field level considering the evolution of vineyard management. Changes in land management were synthesized in transition matrices expressing gains, losses and swaps for each land use category and illustrated using chord and Sankey diagrams. The results showed both a change in land management through a severe transformation of vineyards areas, from goblet to trellised vineyards, during the 1980s and a progressive evolution of land uses from vineyards to urban areas, arboriculture areas and arable lands. This transformation resulted from the local policies on vineyard replanting and the arrival of mechanization.