The dynamics of Mauritia flexuosa (Arecaceae) recalcitrant seed banks reveal control of their persistence in marsh environments

Abstract

Mauritia flexuosa is a neotropical palm associated with marsh environments, having supra-annual fruiting and producing recalcitrant and dormant seeds. We sought to characterize the soil seed banks (SSB) of this species, determine the effects of edaphic and climatic factors on the dynamics of its SSB, and evaluate the influence of permanence in the bank on seed structure and physiology. Newly dispersed and SSB (established more than two years earlier) seeds were collected from four natural populations in the Brazilian Cerrado biome. Evaluations of seeds, embryos, and young plants defined 20 indicators of SSB dynamics that were correlated with 17 physical and chemical soil attributes. Biometric, biomechanical, cytological and physiological evaluations were made in newly dispersed and SSB seeds. Despite producing recalcitrant seeds, Mauritia flexuosa forms persistent SSB in humid environments, and this is the first in-depth report on this topic for angiosperms. Persistence in SSB is affected by predator and pathogen attacks, without the direct influence of physical or chemical soil attributes. Permanence in the SSB does not affect seed viability, as they have great homeostatic capacities, involving water retention and oxidative stress control. Dormancy levels decrease in the SSB, related to increased temperature sensitivity and embryo growth, promoting gradual positive output via germination. Persistent SSB contribute to the reproductive success of M. flexuosa and must be considered in the management of natural populations, as they can contribute to the recovery of degraded areas and, on the other hand, require monitoring of soil moisture, which is essential for its maintenance.