New insights into the plant functional strategies of woody species in the Brazilian Savanna

BACKGROUND AND AIMS: Species maximise fitness in stressful environmental conditions either by the evolution of diverse strategies or by convergence on optimal traits. In tropical savannas, the consequences of conditions like high solar radiation, nutrient-poor soils, seasonal droughts and frequent fires on plant functional strategies remains understudied. Here we aim to investigate the diversity of resource-use strategies in these ecosystems, looking at the trade-offs and coordination across plant organs and the integration of photosynthetic and hydraulic traits. METHODS: We measured a series of key functional traits related to plant structure, photosynthesis, hydraulics, and nutrient use in the leaves and stems of 19 woody species with different leaf phenology in Brazilian savannas. In addition, we incorporated data from the literature to place our findings in a broader ecological context. KEY RESULTS: Our study species account for ≥ 50% of trait variation across global biomes for at least eight traits. While our study species have conservative traits like high xylem embolism resistance, high leaf mass per area, and low leaf P concentrations, they also have high photosynthetic capacity and high hydraulic conductance. Leaf phenology explained part of the variability found, however, a variety of trait combinations and trade-offs existed within phenological groups. Across all species, we observed few trait trade-offs and trait coordination related to conventional resource-use strategies. CONCLUSIONS: We provide new insights into the functionality of savanna species, questioning the notion of a single spectrum of resources use (i.e. the dichotomy between acquisitive and conservative strategies). We emphasize the importance of using multi-dimensional functional approach to provide a better understanding of plant resource-use strategies in environments with co-limiting resources.