Retranslocação de nutrientes foliares de espécies arbóreas de terra firme da Amazônia Central

Abstract

Nutrient retranslocation occurs before leaf abscission, with nutrients being translocated to other parts of the plant. It is an important strategy for nutrient conservation and influences nutrient cycling in ecosystems. However, our understanding of what influences retranslation processes in tropical trees is limited. Thus, to improve our understanding of these processes, we studied the retranslocation of nine macro and micronutrients in a tree community. The objective was to investigate the effects of leaf nutrient concentration in mature leaves, leaf longevity and canopy position in the retranslocation of nutrients in a lowland forest in central Amazonia. For this, we determined leaf nutrients concentration at different leaf ages and the retranslocation efficiency and proficiency in the community. The study was carried out at the AmazonFACE research area, where two towers were used to access the canopy of the twelve tree species studied. The senescent leaves of individual trees were collected every fifteen days from August 2018 to December 2019. We found a strong decrease in P and K at different leaf ages and a contrary tendency for Ca, Fe, Zn and Mn which increased with leaf age. In addition, we found that the nutrient concentration in mature leaves was positively correlated with the retranslocation of C, N, P, Fe and Zn. In addition, we observed that leaf longevity was positively correlated with most nutrients, except for Ca, Fe, Zn and Mn. However, the canopy position was positively correlated only with C, K and Zn retranslocation. Our results showed that in this forest P and K were the most retranslocated nutrients (33.24% and 42.03%, respectively) and that some processes can affect specific nutrient retranslocation in different ways. Our results also emphasize the importance of understanding the interaction of different species in nutrient cycling which should also reflect on individual growth performance. Retranslocation is a fundamental nutrient conservation mechanism in low nutrient tropical forests and should be considered when predicting future scenarios.