Résumé
Agroforestry systems (AFS) can provide many services, among which sequestering atmospheric carbon (C) dioxide (CO2) into both tree biomass and soil organic matter for mitigating climate warming. But atmospheric CO2 uptake is depending on vegetation functioning and phenology can dramatically impact annual primary productivity. Assessing the feedback interactions between climate change and AFS functioning requires monitoring phenology and understanding its determinism. This study aims at providing the first main phenological stages of a black locust (Robinia pseudoacacia L.)-based agroforestry site (DIAMS) in Mauguio (43.612°N, 3.976°E; INRAE DIASCOPE unit), Southern France. Research conducted on DIAMS aims to understand aboveground functioning, belowground plant-soil interactions and the balance of Carbon, Nitrogen and Phosphorus in Mediterranean agroforestry. The experimental site is a 5-ha complete block design (3 blocks) on which three planting systems are compared: forestry (F) i.e. trees planted at high density (1925 trees ha-1), crop (without trees) and agroforestry (AF, 327 trees ha-1). The observations of the main phenological stages were performed on 44 individuals in each block and each planting system (AF or F), except for one plot were 64 individuals were considered. The current stages comprised latent buds, beginning of budbreak, first leaf visible, leaf yellowing and fall. The planting systems will be compared in order to provide different hypotheses in the determinism of the observed phenological patterns. Future observations will cover the inflorescence and fruit development, which can represent an important C sink, despite the young age of this agroforestry site, as well the cambial phenology.