Floristic Composition and Structure Under Contrasting Soil Management Practices for Sustainable Vineyards in the Douro Demarcated Region

This study evaluated how contrasting vineyard soil management practices influence structural-floristic composition and its floristic quality in Mediterranean vineyard agroecosystems. Vegetation responses were assessed under mown sown cover crops (SOWN), mown spontaneous cover crops without soil amendment (SPONT), mown spontaneous cover crops after soil amendment application (AMEND), tillage (TILL), and herbicide application (HERB), and compared with surrounding spontaneous vegetation (SURROUND). Floristic and structural trajectories under different management regimes were also examined over time. HERB, TILL, SOWN, and AMEND showed greater divergence from the floristic and structural characteristics of SURROUND, whereas SPONT showed the highest floristic and structural variability and the greatest percentage of shared flora with SURROUND (36% of shared flora). The composition of the sown mixtures, including the introduction of allochthonous species in SOWN, and management practices, such as annual tillage, compost or biochar applications, and chemical control in the inter-row, were associated with a narrower range of floristic-structural configurations and, in some cases, with the presence of allochthonous flora. Temporal differences did not indicate a significant convergence towards the floristic-structural configuration of SPONT, suggesting that initial conditions and management history may influence vegetation development. Maintaining spontaneous vegetation may therefore retain floristic and structural characteristics more closely associated with SURROUND, providing an alternative approach for biodiversity-oriented vineyard management.