USE OF AGROMINERAL AS SUBSTRATE FOR GROWTH OF EUCALYPTUS SEEDLINGS

Success in the production of eucalyptus seedlings directly affects the development of plants in the field. Several factors influence their initial growth, especially the substrate. This study aimed to evaluate the growth of Eucalyptus globulus seedlings and characteristics of the substrate using silicate agromineral (SA) in different proportions (substrate:SA; v/v): T0 – 100:00%, T1 – 90:10%, T2 – 80:20%, and T3 – 50:50%. The treatments were evaluated using a completely randomized design. Measurements of height (H), stem diameter (SD) and calculation of the H/SD ratio of the plants were performed every 3 weeks, totaling 4 measurements. At the end of the experiment (12 weeks), soil fertility analyses, granulometric analysis (sand, silt and clay) and total chemical analysis were carried out. Due to the chemical and mineralogical composition of SA, its use in substrate in a greater proportion (T3) promoted the increase of exchangeable K, Ca and Si contents, which influenced the increase in the sum of bases and cation exchange capacity. The levels of assimilable P and micronutrients Fe, Cu, Zn and Mn were also higher in this treatment. The increase in SA proportions in the substrate composition also favored increase in the sand fraction and reduction in the clay fraction. As for the growth of seedlings, the results were not significant for H and SD as a function of SA doses, leading to the conclusion that the solubilization and slow release of nutrients by SA did not influence the growth of the plants

Precision and accuracy of sampling methods in thinned Pinus taeda L. stands

Different sampling methods can be used in forest surveys. It is important to know the precision and accuracy of these sampling methods, and which one is the most appropriate in specific conditions of the forest population. The aim of this study was to compare estimates of a forest inventory performed by different sampling methods with forest census results. The sampling methods evaluated were the fixed-area method and the variable-area methods of Bitterlich, Prodan, and Strand. The data were obtained in a 15-year-old thinned stand of Pinus taeda L., located in the municipality of Teixeira Soares, southern Brazil, with a total area of 12.80 ha. Initially, the forest census was carried out, and subsequently, the sample units for each sampling method were distributed in the stand, with a common starting point. The variables used to compare the sample results with the census means were quadratic diameter, number of trees, basal area, and volume, per hectare. Precision and accuracy were evaluated by sampling error and whether the confidence intervals covered the population means, respectively. The fixed-area and Bitterlich methods stood out in precision for all variables analysed. The fixed-area, Bitterlich and Strand methods with proportion to height provided more accurate estimates. The Prodan method provided inaccurate and imprecise estimates for the variables under analysis, except for the quadratic diameter.

RELATIONSHIP BETWEEN MOISTURE CONTENT AND FLAMMABILITY OF CERRADO SPECIES IN SOUTHERN TOCANTINS

This study aimed to analyze the relationship between moisture content and flammability of nine plant species from the Cerrado in southern Tocantins. The species studied were: Machaerium brasiliense, Qualea grandiflora, Luehea grandiflora, Campomanesia guaviroba, Astronium fraxinifolium, Curatella americana, Bauhinia forficata, Vatairea macrocarpa, and Anacardium Occidentale. The plants were analyzed at four moisture contents (M1, M2, M3, and M4). For each level, 50 samples (1 g ± 0.1 g) of each species were collected, and 50 repetitions of burning were performed. The parameters analyzed were: time to ignition (TI), frequency of ignition (FI), duration of combustion (DC), combustion index (CI), flammability value (FV), and height of flames (HF). Our results showed that moisture contents influence flammability in Cerrado plant species. The correlation coefficients between moisture and flammability parameters were r = 0.951 (TI), r = -0.962 (DC), r = -0.977 (HF), and r = -0.988 (FI).

HYPSOMETRY AND VOLUMETRY OF Eucalyptus urograndis IN A CROP-FOREST INTEGRATION SYSTEM

Due to the positive impact that the eucalyptus species has on the Brazilian economy, it is currently the most used forest essence. The objective of this work was to evaluate different hypsometric and volumetric models for Eucalyptus urograndis clones (Eucalyptus urophylla S.T. Blak and Eucalyptus grandis W. Hill ex Maiden) in a Crop-Forest Integration (CFI) system. The trees were evaluated at 7 years of age and arranged in double rows, occupying 20.76% of the total system area. The individuals were subjected to rigorous volumetric cubing according to the Smalian method at intervals of one meter up to full height. The following models were evaluated for the collected height data: Linear, Trorey, Stofels, Curtis, Henriksen, Prodan, Chapman & Richards, Petterson and Bailey & Clutter. Furthermore, the Spurr, Hohenald-Krenn, Stoate, Schumacher Hall, Meyer, Husch, Ogaya and Takata models were used for volume data. The results were determined through the coefficient of determination (R2), standard error of the estimate in percentage (Syx%), significance of the regression coefficients (𝛽) and graphical distribution. The hypsometric model which best fit the database among tested models was the Prodan equation, with a coefficient of determination (R²) of 0.89, while the best result for volumetric models was found using the Meyer model, with a coefficient of determination (R²) of 0.99. All evaluated models were efficient in estimating the height and volume of the Crop-Forest Integration (CFI) system, thus demonstrating that GG100 eucalyptus is a good option in integrated systems.

INPUTS OPTIMIZATION IN THE SEEDLINGS PRODUCTION OF Corymbia citriodora E Eucalyptus dunnii

Corymbia citriodora and Eucalyptus dunnii are species of relevant importance due to the quality of the wood and growth potential in Southern Brazil. Therefore, we aimed to identify containers and doses of controlled-release fertilizer capable of enhancing the morphophysiological quality and growth of these species in the nursery, aiming for the proper management of these inputs. The seedlings were produced in two volumes of containers (50 e 110 cm³), filled with Sphagnum peat-based substrate, mixed with different doses of controlled-release fertilizer (CRF) NPK 15-09-12 (0, 3, 6, 9 e 12 g L-1 of substrates). In addition, the morphological (height, stem diameter, leaf area, dry weight of shoot, root, and total) and physiological (chlorophyll a and b index and quantum yield of the photosystem II) attributes were evaluated. The morphological attributes proved to be suitable indicators of the quality of C. citriodora and E. dunnii seedlings, allowing to recommend the container of 50 cm³ and the doses of 9.0 g L-1 of controlled-release fertilizer for both species. At the same time, the physiological variables evaluated were not responsive to the effect of the treatments.

INFLUENCE OF LOG LENGTH ON THE PRODUCTIVITY OF WOOD HARVESTING AND TRANSPORTATION

The selection of machines and the development of operating systems are the major challenge for reducing costs in harvesting and forest transportation. This work aimed to carry out a technical analysis of harvesting and forest transport activities in two different log lengths (6 and 7m). The operational cycles of the Harvester, Forwarder and combined road train vehicle in mechanized harvest areas were evaluated. The technical analysis was performed through studies of times and movements, determining the operational efficiency and productivity of the machines. According to the results, processing consumed most of the harvester's operational cycle, while in the forwarder, the most time was consumed 35,2 and 45,2 m³·he-1 and 42,84 and 75,42 m³.he-¹. The larger log size led to an increase in the productivity of the harvester by 28% and the forwarder by 48%. Among the studied models of road train vehicles, the one that showed the best results both in the analysis made with a length of 6 m and 7 m, was the dimensions with 2.35 m in width and 2.85 in height. These vehicles had a total gross weight of 63.52 tonnes for logs with a length of 6m and 69.17 tons for logs of 7m, with an 8.17% higher performance compared to 6m logs. With the obtained results it can be concluded that the increase in the length of the logs increased the productivity and the performance of the harvest and the forest transport.

EFFECTS OF METEOROLOGICAL VARIABLES ON Pinus caribaea GROWTH IN DIFFERENT AGES AT THE AMAZON REGION.

This study compares the impact of five meteorological variables on the diametric growth of Pinus caribaea var. hondurensis Barrett & Golfari in Vilhena, Rondônia. One thousand nine hundred sixty-eight trees were evaluated and classified at different ages: 600 trees were one year old; 600 trees were two years old; 768 trees were 13 years. The diameter measurement at the soil level (SL) was conducted in young stands between one and two years old. In the stand with 13 years old, the diameter was measured at 1.3 m (DCH). Using a Pressler borer, 50 increment cores were removed at DCH to measure the tree rings in LINTAB™ 6. The diametric growth was evaluated through the Periodic Increment (PI) for young stands and Current Annual Increment (CAI) for adult stands. The following variables were considered: average temperature (°C), precipitation (mm), solar radiation (Kj m-²), real evapotranspiration (mm), and maximum relative humidity (%). The Pearson Correlation Coefficient (r) proposed by Callegari-Jacques and the coefficient of variation (CV%) were used to establish the relationship between growth and meteorological variables. For young stands, the variables with higher positive correlation were real evapotranspiration and maximum relative humidity. However, the variable with a higher positive correlation in adult stands was average temperature, demonstrating a strong correlation until the sixth year of the species.

PRUNING Araucaria angustifolia FOR KNOT-FREE TIMBER PRODUCTION

Although A. angustifolia is currently economically unimportant, the worldwide trend of conservation through the sustainable use of natural resources together with an intense discussion of governmental regulations and the recent results of genetic breeding started in the 1970s are delivering promising perspectives for a new wave of plantations. This study aimed to determine optimal pruning strategies by evaluating the diameter and height growth of young A. angustifolia trees as affected by different pruning intensities. Pruning quality in terms of occlusion and defect-core size were also investigated. At the age of 6 years, the pruning experiment was started by conducting six different pruning intensities, named after the number of whorls left after pruning (0, 2, 4, 6, and 8), as well as unpruned (U) trees as a control. From the results obtained in the present study, it was concluded that pruning intensity had a significant negative effect on the growth of young A. angustifolia trees. Diameter was more affected than height growth. Pruning young A. angustifolia trees for knotty-free timber production must be conducted keeping 8 whorls after the intervention if no negative effect in current annual increment in diameter is to be observed when compared to unpruned trees. A defect core of 15 cm seems to be a feasible target for the species regarding optimal pruning intensity to avoid losses in diameter growth. This is strongly dependent on a fast occlusion process, which, in turn, is a result of a careful pruning technique.

SURVIVAL AND NATURAL REGENERATION OF FOREST ESSENCES CULTIVATED IN ALTERED AREAS THIRTY-FIVE YEARS AFTER PLANTING

The evaluation of the survival and natural regeneration of tree species in a 35-year-old plantation was carried out to identify the species established in the area, aiming at their recommendation in forest restoration plantations in the State of Acre. In the 1980s, 138 forest species were planted in two experimental units (EU), of 1.38 ha each, in the Zoobotanical Park (ZP) of the Federal University of Acre, Rio Branco campus. The main activities carried out in the area, prior to planting, were agriculture and cattle raising. Survival status was measured through a census of all individuals planted at the time, who were still alive. In addition, all regenerating individuals from planted species were surveyed in the effective planting area of the experimental units. At the time of evaluation, living individuals of 41 and 46 species were found in experimental units 1 (EU-1) and 2 (EU-2), respectively. The species Syagrus sancona, Talisia esculenta, Acacia polyphylla, Couepia bracteosa, Mangifera indica, Syzygium cumini and Copaifera multijuga showed survival rates above 90% in at least one of the experimental units. Only Syagrus sancona and Handroanthus serratifolius presented high survival rates in both experimental. Regenerating individuals of the species Aspidosperma vargasii, Couepia bracteosa, Euterpe precatoria, Handroanthus serratifolius, Oenocarpus mapora, Onychopetalum periquino and Stryphnodendron pulcherrimum were found in the two EU.