physiology. The study was carried out on one- and three-year-old individuals of five tropical tree species assigned to pioneer (P) or non-pioneer (NP) functional groups. Among the species, Cedrela odorata, Luehea seemannii and Hura crepitans showed the greatest biomass accumulation. On our seasonally dry site, species performance during the first year was dependent on a greater investment in above-ground foraging, while performance after three years was mainly related to water relations. However, large biomass accumulations were not simply associated with an efficient water use but also with contrasting water uses, based on inter-specific relationships. Generally, greater carbon isotope discrimination (Δleaf) was related to greater allocation to roots. Species with high Δ leaf generally showed high leaf potential nitrogen use efficiency (PNUE), suggesting that lower water use efficiency (WUE) increases the efficiency of photosynthetically active N. Also, PNUE was negatively correlated to leaf mass per area (LMA), implying that photosynthetically active N is diluted as total leaf mass increases. Finally, no distinction in measured traits, including biomass accumulation, was observed between the two functional groups.