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Sawnwood of teak (Tectona grandis L. f.) from a Costa Rica plantation was thermally treated at different process conditions using thermo-vacuum technology. The main objectives of the study were to find the optimal combination of the process parameters, i.e. temperature (T), and duration (t), in order to minimise the colorimetric difference between sapwood and heartwood, and to evaluate the influence of the treatment on the modification pattern of physical properties of the material. The resulting mass loss (ML), hygroscopicity (H), dimensional stability (ASE), and lightness (L) were measured and compared. As expected, the temperature (T) is the main parameter influencing the extent of modification. The measured ML values turned out to be moderate even at high T values if compared with other hardwoods. The temperature range between 180 °C and 190 °C minimizes the colorimetric difference between treated sapwood and not treated heartwood. [ABSTRACT FROM AUTHOR]

Efforts to model woody debris dynamics are limited by our empirical understanding of the patterns and drivers of decomposition. This knowledge gap is significant in tropical forests, particularly in the dry tropics where research has been minimal and where forest regeneration is a management priority. Here, we coupled trait-function relationships in decomposing logs with indices of microbial and insect activity in a regenerating Costa Rican dry forest. We cut and placed logs (∼18 cm dia) of eight tree species in ground contact at two sites. We assessed density loss and element dynamics in sapwood and heartwood twice annually over two years. At time 0 and year 2, we measured lignin, nitrogen, structural carbohydrates, extractives, insect galleries, and two residue 'signatures' of fungal rot type: dilute alkali solubility (DAS; higher for brown rot) and lignin:glucan loss (higher for white rot). After two years, sapwood mean density losses ranged from 11.6 to 44.4% among tree species (excluding one thoroughly-degraded species). The best predictor of sapwood density loss was initial pH, but this correlation was negative, contrasting positive correlations proposed for temperate forests. Mean heartwood density losses were consistently less than those in sapwood, and although heartwood extractives contents were as high as 16.4%, trait correlations were insignificant. Insect galleries contributed little to density loss (<3%), and DAS and lignin loss patterns indicated dominance by white rot fungi. This was often matched by dense fungal zone line patterns (spalting), outlining many small territories. Perhaps as a consequence, element patterns were spatially variable, with overall trends roughly similar to those from temperate studies (e.g., Ca gain, P, K loss). Estimated CO2 fluxes from logs ranged from ∼25 to 75% percent of annual fluxes from litter fall. This collectively implies an important role for wood decomposition in dry forest carbon cycling, and in our case, it shows an interesting pattern suggesting high decomposer spatial complexity but low functional diversity. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to investigate the fuel characteristics (calorific value and fuel value index) of 10 fast-growing species in plantations in Costa Rica. The effect of the chemical properties, extractives and moisture content were evaluated. The results revealed that the gross calorific value varied from 16.5 to 20.6 MJ kg−1 for sapwood, and from 16.3 to 20.1 MJ kg−1 for heartwood. No consistency was observed with regard to which type of wood (sapwood or heartwood) had the highest gross calorific value. Large variations among the species were observed in the case of the fuel value index. For heartwood, the slope gradient of linear correlation was affected by lignin and extractives in sodium hydroxide and dichloromethane solution, whereas in the case of sapwood, only ashes content affected significantly to calorific value. For chemical parameters or the amount of extractives, carbon, nitrogen and lignin contents, ashes and extracts in dichloromethane influenced significantly the calorific value of heartwood. The calorific value in sapwood was affected by the amount of extractives in ethanol–toluene and the amount of ashes. Finally, the fuel value index was affected by the quantity of carbon, the extractives in sodium hydroxide and dichloromethane. [Copyright &y& Elsevier]

The Dipteryx genus has a natural distribution throughout several tropical countries in Latin America. This taxon has several tree species, all recognized for their high-density wood. The objective of this research was to study the variation and genetic control of several wood properties, including bark, sapwood, heartwood, green density (GD), specific gravity (SG), moisture content in green condition (MC-G), and mechanical properties, in a Dipteryx panamensis provenance/progeny test at 8 years old. The results showed that bark varied little among families and provenances, but heartwood (diameter and percentage) showed high genetic variation. SG and MC-G showed significant variation between provenances and families, while GD showed little variation. Among the mechanical properties evaluated, the greatest genetic variation was observed in the MOR in bending and shear stress. Families from the Coope San Juan provenance registered the highest values in all wood properties investigated, and families from Puerto Viejo obtained the lowest. Family heritability and the coefficient of genetic variation exhibited high values in heartwood/sapwood and the MOR in bending (h2 > 0.9 and CV > 20%) and lower values in SG, MC-G, compression stress, and shear stress. D. panamensis wood properties have a high potential to be improved through breeding programs. [ABSTRACT FROM AUTHOR]

We developed allometric equations to predict whole-tree leaf area (Al), leaf biomass (Ml) and leaf area to sapwood area ratio (Al:As) in five rain forest tree species of Costa Rica: Pentaclethra macroloba (Willd.) Kuntze (Fabaceae/Mim), Carapa guianensis Aubl. (Meliaceae), Vochysia ferruginea Mart. (Vochysiaceae), Virola koshnii Warb. (Myristicaceae) and Tetragastris panamensis (Engl.) Kuntze (Burseraceae). By destructive analyses (n = 11–14 trees per species), we observed strong nonlinear allometric relationships (r2 ≥ 0.9) for predicting Al or Ml from stem diameters or As measured at breast height. Linear relationships were less accurate. In general, Al:As at breast height increased linearly with tree height except for Pentaclethra, which showed a negative trend. All species, however, showed increased total Al with height. The observation that four of the five species increased in Al:As with height is consistent with hypotheses about trade-offs between morphological and anatomical adaptations that favor efficient water flow through variation in the amount of leaf area supported by sapwood and those imposed by the need to respond quickly to light gaps in the canopy. [ABSTRACT FROM AUTHOR]