The broad diffusion and active management by man of the sweet chestnut in past centuries has resulted in the establishment of the species at the limits of its potential ecological range in many European mountain areas. This raises the hypothesis that the chestnut tree has considerable plasticity, enabling the species to adapt to very different sites and conditions. In order to test this hypothesis, we applied the pipe-model approach, postulating the constancy of the leaf area/sapwood area (LA/SA) relationship for single portions of a tree. We analysed the variation of the LA/SA coefficient among chestnut trees subjected to different sites conditions (e. g., convex vs. concave sites) in order to gain insight into the plasticity of the species. The results confirmed that the sweet chestnut is able to greatly vary the allocation of resources with respect to environmental conditions. In particular, the LA/SA coefficient was high when trees were growing in sites with good water supply (e. g., concave sites or gentle slopes) and low in water stressed convex or steep sites.