Variations in productivity and wood properties of Amazonian tachi-branco trees planted at different spacings for bioenergy purposes

Tachi-branco ( Tachigali vulgaris , L.F.Gomes da Silva & H.C.Lima) is a leguminous tree species native to the Amazon rainforest that has drawn attention for its remarkably fast growth, a required trait for biomass/bioenergy plantations. In evaluations of biomass production and wood properties of T. vulgaris planted in homogeneous plantations at different spacings in the Amazonian state of Pará, Brazil, biomass of 7-year-old trees was quantified for individual trees and the entire population. Wood was also sampled to assess properties relevant to bioenergy applications. The choice for spacing dimension for planting nonclonal T. vulgaris should consider whether the priority is greater productivity per tree, achieved with greater spacings (9.0 m 2 and 12.0 m 2 ), or productivity per area, achieved with closer spacings (6.0 m 2 and 7.5 m 2 ). Genetic variability of the T. vulgaris seed stand and/or high heritability of wood traits overcame the effect of different spacing on all morphological, physical, chemical and energetic properties of T. vulgaris wood. This species has moderate basic density when cultivated at spacings larger than 6 m 2 and net heating value above 7.95 MJ/kg, which is suitable for bioenergy purposes. The high variation in wood properties within tree spacing is strongly indicative of great potential for genetic breeding. The fast growth and the suitable moderate wood basic density confirm the outstanding potential of homogeneous plantations of T. vulgaris for providing wood for bioenergy.