Effects of planting spacing on chemical, physical and energetic properties of biomass accumulation in a plantation of Eucalyptus tereticornis Sm

ABSTRACT Background: The use of tree plantations for energy purposes has shown an increase in their use in tropical regions due to the species' rapid growth and low cost of energy generation. This has led to the development of optimization studies of crop conditions. However, the determination of the effect of spacing on physical, chemical and energy properties has not been precise for Eucalyptus tereticornis, which limits the development of plantations with optimal silvicultural conditions. Results: The study analyzed the growth and chemical, physical and energetic properties in a four-year-old plantation. The results showed that mortality ranged from 29 to 69%, being the 1.0 x 2.0 m spacing the one that presented better yields with a significantly higher diameter and height (9.13 cm and 14.17 m, respectively) with a higher biomass accumulation (140.04 ton ha -1 without treetop) concentrated mainly in the stem. The other two spacings presented statistically lower and non-significant values. The physical properties were obtained densities of 0.57 to 0.66 g cm -3, with a specific density of 0.58 and moisture content of 57.7%. The chemical properties only showed differences in carbon concentration (50.11 to 69.16%). The energetic properties showed a caloric power between 4780 to 6059 kcal kg -1, with a variation in volatile content of 10.9% and 1.6% in ash. Conclusion: The planting spacing generates a gradient in the production, mortality and property of the biomass, being the spacing of 1.0 x 2.0 m being optimum for establishing the study species for Costa Rica.