Acai Palm Management Disturbs Seed Rain and Soil Seed Bank of an Amazonian Estuarine Forest

The exploitation of non-timber forest products has been proposed as a sustainable way to exploit tropical forests, but such an opportunity remains to be proved. Here, we examine the impact of intensive acai palm (Euterpe oleracea) management on the seed rain and soil seed bank in an estuarine forest landscape with a long history of forest management by locals in the Amazon region. Seed rain (100 80 cm(2) collectors) and soil seed bank (100 30 cm(2) samples) were monitored through a year across 20 forest stands, covering a gradient of acai stem density (50-3575 acai stems per ha). Seed rain and bank were dominated by acai seeds (85.5%-85.8%) and by excluding them, seed rain and bank were low density and species poor, capturing a tiny subset from the local (17.91%-19.40%) and landscape woody flora (11.82%-14.55%). Moreover, autochthonous and vertebrated-dispersed predominated as well as those from tree species considered useful by locals. Overall, acai stem density positively affected acai seed abundance in the seed rain and negatively affected seed pools in the bank in relation to abundance of seeds and vertebrated dispersed, while adult tree species richness and density and accessibility to forest stands were associated with more diversified seed pools. Thereby, forest stands are exposed to different levels of acai management (high vs. low intensity) supported taxonomically distinct seed pools. Our results suggest that acai intensification disturbs seed rain and soil seed bank with potential impacts on forest regeneration and the forest integrity standards required to consider acai fruit production as sustainable according to current legislation.