Effects of nutrient addition on polyphenol and nutrient concentrations in leaves of woody species of a savanna woodland in Central Brazil

We investigated whether changes in nutrient availability affected N, P, S and polyphenol concentrations in different leaf-development stages of three brevideciduous and three evergreen dominant woody species in a nutrient-limited savanna woodland in Central Brazil. Treatments included eight years of annual fertilization with 100 kg ha(-1) of N, P, N plus P and control, each replicated in four randomized 15 x 15-m plots. All species increased S concentrations (minimum 28%) in young and mature leaves in fertilized plots. Dalbergia miscolobium decreased total phenol concentrations with P (-34.3%, -23.7%) and NP fertilization (-28.2%, -17.1%). Blepharocalyx salicifolius increased total phenol (27.6%, 18.8%) and tannin (46.3%; 43.5%) in P fertilized and increased total phenol (33.9%) and tannin (27.8%, 43.5%) in NP fertilized plots. Total phenol concentration decreased with leaf age in Ouratea hexasperma, Styrax ferrugineus and Blepharocalyx salicifolius, which also decreased tannin concentration with leaf age. For all treatments, brevideciduous species had higher N, P, total phenols and tannin concentrations and lower S concentration than evergreens. These differences between phenological groups suggest that tropical ecosystems responses to environmental changes are more complex than anticipated by global vegetation models, with consequences for predictions in ecosystem functions and resilience.