In 2002, the Brazilian Ministry of Science and Technology launched the ProBiodiesel Project, designed to promote the production and use of biodiesel. This study evaluates the potential of two native Attalea palm species in Southwestern Amazonia as a source of oil for regional production of biodiesel and seeks to generate ecological knowledge to facilitate sustainable management of native palm fruits for oil extraction. Attalea palms are common to forests as well as pastures in Amazonia, and copious amounts of oil can be extracted from the fruits’ mesocarp and endosperm. Attalea species alternate between pistillate, staminate, and sometimes hermaphroditic inflorescences on the same plant, resulting in highly variable fruit production. We monitored flowering and fruiting phenologies of Attalea phalerata Mart. ex Spreng. and Attalea speciosa Mart. ex Spreng. (Arecaceae) in pastures and old-growth forests of Acre and Rondônia, Brazil, over 18 months. We also measured palm height, canopy position and illumination, and leaf production rates.

Results/Conclusions

A. phalerata and A. speciosa consistently produced more staminate than pistillate inflorescences, and while palms growing in pasture produced flowers and fruits year-round, forest palms flowered and fruited during distinct seasons.  Switches between pistillate and staminate inflorescences were common within individuals, but we found no correlation with stem height, light availability, or leaf production rates.  After 18 months, A. phalerata produced two times more staminate and pistillate inflorescences in pasture than in forest.  A. speciosa, on the other hand, showed no significant difference in staminate inflorescence production between pasture and forest, while pistillate inflorescence production was significantly higher in pasture.  A. phalerata demonstrated greater biodiesel potential in pasture than in forest due to higher infructescence production.  A. speciosa exhibited strong potential for oil production in pasture and in forest due to high average fruit production per palm (120 kg) and high mean densities in both environments (30 ha^-1).  These palms can annually produce an estimated 140 kg of oil per hectare in either environment.  Considering average annual A. phalerata fruit production (60 kg) and adult densities in pasture (10 ha^-1), one hectare of pasture with A. phalerata can provide an estimated 45 kg of oil per year.