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Dendrocalamus asper (Schult. & Schult.f.) Backer and Guadua angustifolia Kunth are cultivated in Costa Rica for their commercial benefits, and their application in different constructions projects. G. angustifolia has two varieties: the Caribe and the South varieties. Existing knowledge of the variation in culm properties of these two varieties and the differences between the two species is limited. The main objective of this study was to evaluate the physical and mechanical properties of G. angustifolia varieties and D. asper planted at various heights at the same site in the Atlantic Region of Costa Rica. Some properties exhibited statistical differences between species, but almost no properties of the two varieties of G. angustifolia differed significantly. D. asper exhibited the highest levels of moisture content, specific gravity, density, parameters of flexion test, tension stress, diameter, area and frequency of bundles specifically from base to 25% of height, although beyond this height, no significant differences were observed between species. Regarding the two varieties of G. angustifolia, external and internal diameters, wall thickness culm, moisture content, specific gravity, density, parameters of flexion test, tension stress, diameter, area, and frequency of bundles showed no statistical differences. These results indicate that the differences observed in the two varieties of G. angustifolia may be attributable to the adaptation of the species to distinct soil and climate conditions for growth. When the two varieties were planted at the same site, no differences were observed.

ABSTRACT Research and implementation of energy crops using short-rotation woody species (SRWC) are increasing in Latin America, especially for biomass production and use in bioenergy. For this purpose, one of the main factors to consider is species assessment. Therefore, the objective of the present study was to evaluate the growth characteristics, the production and distribution of biomass, and the chemical, physical, and energetic properties of the biomass of three-year-old Dipteryx panamensis plantations in SRWC in three different spacings (1.0x2.0 m, 1.0x0.5 m and 1.0x1.0 m) and establish the best spacing condition for this tropical species. The results showed that the production of biomass varies between 1.1 and 42.36 t.ha-1, and that 33-44% of the production are concentrated in the leaves. At three years, the SRWC presented 50% mortality, with a diameter of 4.8 cm at 30 cm-height from the ground, with total tree heights ranging from 5.17 to 6.98 meters. The evaluation of the biomass showed a calorific value between 18.9 and 19.4 MJ/kg, less than 1.81% of ash content and 86% of volatile content. As for the effect of the spacing, the green density of the wood and the moisture content increased with increasing spacing, while spacings of 1.0x1.0 m and 1.0x0.5 m showed the best behaviour regarding annual biomass production.