Long-term legacy of sowing legume-rich mixtures in Mediterranean wooded grasslands

The oversowing of legume-rich mixtures is a management practice gaining importance in Mediterranean silvo-pastoral farms due to enhanced forage production, quality, and ecosystem service provision. However, the oversowing of legume species can be expensive in silvopastoral farms due to the high cost of legume seeds and seeding operations and low persistence under inadequate management. The study aimed to assess the long-term impacts of legume-rich mixtures oversowing on pasture production of Mediterranean wooded grasslands with a remote sensing approach. The study was conducted on six Dehesa farms in Western Spain, where legume mix-tures had been sown in different years from 2002 to 2015 in part of the farms. The effects of legume species oversowing were assessed by analyzing the variation across years of a set of derived vegetation indices in sown and unsown areas of each farm. Among all considered vegetation indices, the Simple Ratio (SR) and the Normalized Difference Vegetation Index (NDVI) showed the highest capacity in estimating grassland yield (Pearson's r = 0.58 and 0.52, P < 0.01, respectively) and N content (r = 0.52 and 0.48, P < 0.05, respectively). All normalized vegetation indices increased after the sowing and remained significantly higher than before sowing (P < 0.001) for the whole monitoring period. Furthermore, the sowing also positively affected the temporal stability of each vegetation index, being interannual variability significantly higher (P < 0.01) before the sowing than after. The study confirmed the hypothesis that the oversowing of legume-rich mixtures in Mediterranean wooded grasslands effectively improves intra-and interannual biomass production and stability. Remote sensing using Landsat images proved to be an effective tool to assess the impacts of grassland man-agement practices in the long term in silvopastoral systems.