Grapevine rhizosphere microbial activity and nitrogen nutrition vary with tree planting age in a temperate vitiforestry system

Agroforestry, i.e., the planting of trees within agricultural systems, has been shown to enhance soil fertility, biodiversity, and the functioning of ecosystems. In temperate vineyards, vitiforestry represents a new type of agroforestry combining perennial grapevines and trees, either within or around vine rows. However, the effects of trees planted within vine rows on belowground microbial processes and grapevine growth remain underexplored. In this study, we investigate soil physicochemical properties, microbial enzymatic activities associated with carbon (C), nitrogen (N), and phosphorus (P) acquisition, and nutrient acquisition strategies in bulk soil and grapevine rhizosphere compartments in a vineyard where trees were planted within vine rows either five years ago (5YO) or ten years ago (10YO). The results indicated that soil organic C and total N contents were higher near 10YO trees compared with soils from control rows (i.e., far from trees). Enzymatic activities increased in the rhizosphere of grapevines growing near trees compared with those growing farther away, and this effect was more pronounced near the 10 years tree planting cohort. Vector analysis revealed a shift toward greater relative investment in P-acquiring enzymes near older trees. The presence of trees was associated with higher vine nitrogen status, without affecting berry yield per vine. Overall, trees enhanced grapevine rhizosphere enzymatic activities and improved vine nitrogen status, while increasing soil organic C, offering a potential pathway toward more resilient and sustainable viticultural systems.