Resumo em Inglês:

Abstract The impact of forestry practices was evaluated on Eucalyptus’s growth variables and mortality dynamics. An experiment was conducted in Uruguay over sixteen years, sixteen spacing and thinning treatments were compared depending on the genetic material and productive objective. Tree height and diameter at breast height were assessed annually. All variables were analyzed using linear mixed models. Kaplan-Meier survival analysis and the Log Rank test were used to compare tree survival. 460 trees ha-1 from seed material resulted in the highest individual basal area (0.023 m2), while treatments with 2000 trees ha-1, without thinning, generated a greater yield per hectare (1014 m3 ha-1). Variations in mortality were detected in higher-density treatments (above 800 trees ha-1). This study underscores the critical importance of managing spacing, genetic material, and thinning practices to optimize Eucalyptus growth.

Resumo em Inglês:

Abstract The work proposes the use of multi-walled carbon nanotubes in various concentrations treated in nitric acid (f-MWCNT) as a filler for urea-formaldehyde resin to produce birch plywood with improved physical-mechanical, water-resistant and thermal properties. The MWCNTs were characterized using transmission electron microscopy, IR and Raman spectroscopy, and the zeta potential was determined. The thermal stability of plywood on the UFR/f-MWCNT adhesive composition was assessed and a higher thermal stability of plywood was revealed when a nanofiller was added to the resin. The modulus of rupture increased by 62.7% and the modulus of elasticity by 113% with the addition of 1.5% f-MWCNT. A decrease in water absorption was established by 43%. A steady decrease in the emission of free formaldehyde from plywood was determined. The possibility of intermolecular interaction between the functional groups of f-MWCNT and urea-formaldehyde resins has been established.

Resumo em Inglês:

Abstract Knowledge of the characteristics and durability of every wood species is essential so it can be better directed for the correct harnessing. In a wood rot field test, this work aimed to determine the natural durability of timber species from the Brazilian dry forest, Mimosa tenuiflora and Mimosa caesalpiniaefolia . The slats were buried in the ground up to half their length and distributed in the field according to a completely randomized experimental design. Annual assessments were performed to determine the deterioration rate. Furthermore, mass loss and condensed tannin content were quantified. The condensed tannin content found for the species was 4.40% for M. caesalpiniaefolia and 3.99% for M. tenuiflora . The results of 3 years of evaluation of the test make it possible to understand that both species presented durable wood, where M. caesalpiniaefolia presented a deterioration rate of 77.27%, while M. tenuiflora presented 66.27%, making them of high natural durability.

Resumo em Inglês:

Abstract Given escalating environmental concerns and stricter regulations, there’s a pressing need for sustainable materials. Eco-composites, which blend natural fibers with polymer matrices for reinforcement, are gaining traction. This study stands out by employing Australian royal palm stem fibers within a polystyrene matrix for eco-composites. The research involved assessing thermal stability, quantifying lignin/carbohydrate content, and measuring moisture levels. Scanning electron microscopy was utilized to examine fiber structure. Results from evaluations of thermal and mechanical properties underscore the high-performance reinforcement potential of Australian royal palm fibers, suggesting their suitability for various eco-composite applications. Beyond meeting the demand for sustainable materials, this project introduces an innovative use of these fibers, broadening their potential applications and advocating for greener, socially responsible industry practices.

Resumo em Inglês:

Abstract The objective of this study is to evaluate changes in vegetation cover in the Ilhéus-Itabuna geographic intermediate region from 1984 to 2019 using the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Soil-Adjusted Vegetation Index (SAVI). Data was processed through the Google Earth Engine programming interface, using image collections from the TM/Landsat 5 and OLI/Landsat 8 sensors. After creating the indices, areas with different uses were selected, and the NDVI time series graphs were created. It was found that the vegetation density in the region decreased from 1984 to 1999 and increased from that year. The NDVI and EVI showed similar behavior, unlike the SAVI, which lower averages. Average NDVI values were higher in (June-August), due to the association of these conditions with higher soil moisture. In the pasture area, peaks of heat (January-March) drove vegetative activity due to the favorable climate and availability of water and sunlight.

Resumo em Inglês:

Abstract The objective was to evaluate the spatial distribution of chemical and textural soil variables in a multistrata agroforestry system. A total of 73 georeferenced soil samples were collected at depths of 10-20 cm and 20-40 cm. The studied parameters were: pH H2O , potential acidity (H+Al), calcium (Ca 2+ ), magnesium (Mg 2+ ), aluminum (Al 3+ ), sodium (Na + ), potassium (K + ), phosphorus (P), organic carbon (C org ), cation exchange capacity (T-value), base saturation (V-value), total clay, total sand, and silt. Principal component analysis (PCA) was performed in R software using the FactoMineR and Factoextra packages. For variables with spatial dependence, ordinary kriging was performed using the best-fitted model. For variables without spatial dependence, inverse distance weighted (IDW) interpolation was applied (power = 2). The spherical model was the best fit for chemical attributes. IDW interpolation accurately mapped the textural attributes. It was concluded that geostatistics enabled a detailed analysis of chemical and textural attributes.