Manilkara Huberi Research Articles

Thermal Decomposition and Kinetic Analysis of Amazonian Woods: A Comparative Study of Goupia glabra and Manilkara huberi

This study presents a detailed analysis of the thermal degradation and kinetic behavior of two Amazonian wood species, Goupia glabra (cupiúba) and Manilkara huberi (maçaranduba), using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR-ATR), and direct infusion mass spectrometry (DIMS). Wood samples were subjected to controlled heating rates of 20, 40, and 60 °C/min from 25 to 800 °C under an argon atmosphere. TGA revealed moisture evaporation below 120 °C, with hemicellulose degradation occurring between 220 and 315 °C, cellulose decomposition between 315 and 400 °C, and lignin breakdown over a broader range from 180 to 900 °C. The highest rate of mass loss occurred at 363.99 °C for G. glabra and 360.27 °C for M. huberi at a heating rate of 20 °C/min, with shifts to higher temperatures at faster heating rates. Activation energies were calculated using Arrhenius and Kissinger models, yielding values between 53.46–61.45 kJ/mol for G. glabra and 58.18–62.77 kJ/mol for M. huberi, confirming their stable thermal profiles. DSC analysis identified a significant endothermic peak related to moisture evaporation below 100 °C, followed by two exothermic peaks. For G. glabra, the first exothermic peak appeared at 331.45 °C and the second at 466.08 °C, while for M. huberi, these occurred at 366.41 °C and 466.08 °C, indicating the decomposition of hemicellulose, cellulose, and lignin. Enthalpy values for G. glabra were 12,633.37 mJ and 18,652.66 mJ for the first and second peaks, respectively, while M. huberi showed lower enthalpies of 9648.04 mJ and 14,417.68 mJ, suggesting a higher energy release in G. glabra. FTIR-ATR analysis highlighted the presence of key functional groups in both species, with strong absorption bands in the 3330–3500 cm−1 region corresponding to O-H stretching vibrations, indicative of hydroxyl groups in cellulose and hemicellulose. The 1500–1600 cm−1 region, representing aromatic C=C vibrations, confirmed the presence of lignin. Quantitatively, these results suggest a high content of cellulose and lignin in both species. DIMS analysis further identified polyphenolic compounds and triterpenoids in M. huberi, with major ions at m/z 289 and 409, while G. glabra showed steroidal and polyphenolic compounds with a base peak at m/z 395. These findings indicate the significant presence of bioactive compounds, contributing to the wood’s resistance to microbial degradation. This comprehensive thermal and chemical characterization suggests that both species have potential industrial applications in environments requiring high thermal stability.

Sustainable forest management for timber and non-timber resources in the Amazon forest under concession

The Amazon biome is one of the largest in terms of area and biodiversity. It provides impressive ecosystem services that are crucial to planetary functions, for example global precipitation patterns. Besides, it provides important timber and non-timber products that are crucial for local communities and even international markets. The aim of this study was to conduct a phytosociological analysis to select the species with important ecological functions and with commercial interest for timber and non-timber forest products (NTFP). Forest inventory data were collected were collected from 4 Annual Production Units (APUs) at the Paru State Forest. The 5 species with highest Importance Value Index (IVI) were: Chrysophyllum lucentifolium, Micropholis venulosa, Handroanthus serratifolius, Handroanthus impetiginosus and Manilkara huberi. These species presented commercial volume in the diameter classes of 40 to ≥ 170 cm. The species providing NTFP (Carapa guianensis, Bertholletia excelsa and Copaifera guianensis) presented IVI in the 1, 9, and 34 positions, respectively. The species Carapa guianensis presented more individuals in the 40 and 80 DBH classes. Bertholletia excelsa was the only one presenting individuals with DBHs exceeding 140 cm. Copaifera guianensis was the less common species. We concluded that all the 5 species producing timber are viable for sustainable forest management. Regarding the non-timber forest species, forest management need to be focused in Carapa guianensis and Bertholletia excelsa.

Physical properties and predominant compounds of Guarea trichiloides L., Licaria aritu Ducke and Manikara huberi (Ducke) A. Chev

Wood is composed of macro-molecules (cellulose, hemicellulose and lignin), which are the structural components, and micro-molecules or secondary metabolites (minor components of around 2% to 5%), responsible for the defense activities of the plant species in its environment. In this article, we evaluate the physical properties and the predominant secondary metabolites in woody residues of Guarea trichilioides L., Licaria aritu Ducke and Manilkara huberi (Ducke) A. Chev. The methanolic extract of G. trichilioides, which was subjected to chromatographic fractionation, provided piceatannol. The hexane extract of L. aritu showed an abundance of Aurein A. The hexane extract of M. huberi presented β-sitosterol and lupeol. After chromatographic fractionations, the methanolic extract resulted in the purification of p-hydroxybenzaldehyde and 2β,3β,6β,28-tetrahydroxyolean-12-en-23-oic acid 23-O-α-L-rhamnospyranosyl ester. Wood from M. huberi and L. aritu showed high density. The types of molecules identified in the three specimens are reported to play an important role in the plant as a defense against pathogens and are markers of the evolutionary process.

Facial Biocosmetics Based on Natural Dyes from Amazon Wood Residues

ABSTRACT The occurrence of several flavonoids with antioxidant and anti-inflammatory potential properties in wood may have a viable application in the biocosmetic industry. This paper studies the technical viability of redirecting wood residues of the main commercialized Amazonian species, Dipteryx odorata (cumaru), Manilkara huberi (ironwood), Hymenaea courbaril (Brazilian cherry) and Handroanthus serratifolius (yellow ipe), to obtain natural dyes for facial biocosmetics development. For each dye sample, phytochemical profile of phenolic compounds and the total flavonoids content expressed in rutin and quercetin (ug mL–1) was determined. Wood residues extract yield was 6.5% for cumaru, 8.1% for ironwood, 16.3% for Brazilian cherry and 8.8% for yellow ipe. The physical-chemical properties were compliant with the official compendia. TLC-analysis revealed the presence of flavonoids (quercetin) and hydrolyzable tannins (gallic acid). Concentration of total flavonoids content expressed in rutin and quercetin varied between 0.106 to 7.5 and 0.1 to 3.12ug.mL–1, respectively, for all species. Facial biocosmetic formulations with organoleptic properties (appearance, color and odor) suitable for facial use could be obtained from ironwood, Brazilian cherry and yellow ipe dyes. Therefore, Amazon species wood residues reuse is an innovative and sustainable technological strategy to add value to bioproducts of Amazon biodiversity, contributing to the region’s socio-economic development.

Use of impulse tomography in the evaluation of Manilkara huberi (maçaranduba) managed of the Amazon rainforest

ABSTRACT The use of new technologies in forest management, such as impulse tomography, can help in the selection of standing trees and reduce wood waste. This study aimed to evaluate the applicability of impulse tomography in Manilkara huberi (maçaranduba) trees managed in the Amazon rainforest (Amazonas, Brazil). A total of 10 trees were selected at the exploration site, and visual assessments and trunk readings were performed with sonic tomography. The graphic simulation of the maçaranduba trees using the PICUS software presented the geometric contours of the studied trunks. The tomographic images revealed heterogeneous tissue due to the variation of pixels in 50% of the trees. The blue color was accentuated in the greater proportion of the wood, which is associated with the reduction in speed that can be interpreted as “tension wood” or even indicative of the presence of hollow trees. The distance traveled by sound propagation in healthy individuals appears to not imply the study, with values above 1421.72 m/s indicating healthy individuals. The results obtained in this research provide important answers for the sustainability of forest management in the Amazon and reduce unnecessary felling of unwanted individuals (with hollows, degraded), thereby significantly reducing the generation of waste.

Experimental investigation on variability in properties of Amazonian wood species Muiracatiara (Astronium lecointei) and Maçaranduba (Manilkara huberi) focusing guitar fingerboards manufacturing

In face of scarcity in the supply of non-traditional Brazilian woods properly treated for use in high quality musical instruments, pieces of Amazonian wood species muiracatiara (Astronium lecointei) and maçaranduba (Manilkara huberi) purchased in the common internal Brazilian timber market were examined. These species were pre-selected for use in fingerboards of acoustic and electric guitars due to similar properties with ebony (Diospyros crassiflora). Variabilities of elastic modulus parallel to grain and density were investigated inside wooden pieces. In addition, referred parameters were used in calculation of speed of sound. Statistical tests were performed in order to compare both species and revealed inequality for variances of dynamic elastic modulus (Ed) and speed of sound, but equality for density. Equality of means was also examined via unequal variance t-test. Despite color differences, lower variability of M. huberi led to the indication of this species as likely capable to substitute satisfactorily ebony in fingerboards manufacturing.

Pattern and spatial associations of commercial trees in the Amazon

ABSTRACT: This study was conducted to establish the pattern and the spatial associations of the Amazon commercial tree groups. In a region extending across 2,000 ha in the Tapajós National Forest (FNT), Pará, a forest census was conducted. The census included commercial trees of perimeter at breast height (PBH), equal to or greater than 158 cm and the Cartesian coordinates of their bearings. Using Ripley’s K function, the spatial pattern was discerned, with 5 m radius being assumed, and maximum distances varying up to 1,500 m. Then, with 99.8% probability for both, 500 Monte Carlo simulations were performed for the univariate K function, and 500 toroidal simulations were done for the bivariate function.The commercial tree groups, which revealed an aggregated spatial pattern in a minimum of approximately 50% of the analysis distance were namely, Astronium lecointei, Bagassa guianensis, Couratari guianensis, Manilkara huberi, Mezilaurus itauba, and Vochysia maxima. In Brazil, the commercial tree groups, based on the commercialization criteria for tropical trees show random and aggregated spatial patterns with associations of spatial independence.

Diagnosis of hollow trees in an area of effective sustainable forest management in the Amazon forest

The sustainable practices of Forest Management activities are used with the objective of minimizing impacts to the environment, as well as exploring tree individuals with qualities that aim at the highest volumetric yield in sawmills. However, some characteristics may not be diagnosed before logging, as is the case with hollow trees, commonly found in forested areas. Thus, the objective was to diagnose the occurrence of hollow trees in two areas of forest exploitation, for the knowledge of individuals at the family and botanical species level. In order to carry out thediagnosis of the occurrence of hollow trees, data on the effective exploitation of trees in the Company's Forest Management areas were obtained through a collection of information on two Annual Production Units - UPA, named according to the company's specification as named as UPA ITP11 and UPA FLA01. In each UPA, tree individuals were identified by gender, species, family, distribution, presence of hollowness and the basic density of their wood. The results show that in the UPA ITP11 area, 7.38% of the total trees explored, had hollowness, while in the UPA FLA01 area it was 4.88% and that the majority had high basic density. Twenty botanical families were identified in the exploration areas, where the Leguminosae family obtained the greatest representation. A total of 49 botanical species explored were identified, being Manilkara huberi (Ducke) Stanley, as basic high density wood. Regarding the frequency of occurrence of hollowness, the species Dinizia excelsa Ducke, popularly known as Angelim Vermelho, stood out for the two areas under study. However, it is shown the considerable existence of hollow trees among the trees selected for forest exploitation, reinforcing the importance of better targeting of appropriate methodologies for their identification, as well as, the better volumetric utilization of logs in sawmills, in order to certify the sustainability for the activity, regardless of the structural aspect of forestry individuals.

Ecological panels as an alternative for waste from mechanical processing of Amazonian species

The wood residues resulting from the operational phases in companies in the forestry market are normally considered by-products and, therefore, are discarded or reused for energy production, however, this material has a greater potential, such as the generation of new products through agglutination, which may generate a new segment in the wood industry, causing competition between products of native and planted species. This research aimed to develop agglomerated panels using residues of two tree species from the Amazon (Dinizia excelsa Ducke and Manilkara huberi (Ducke) Chevalier) and a mixture of commercial Amazonian species of high density, with the purpose of greater added value and a possible solution to reduce the negative environmental impacts of carbon emissions. The experimental design consisted of three treatments with five repetitions in each. Experimental panels were produced with a nominal density of 0.80 g/cm³, using castor oil-based resin with 10% percentages. The panels were pressed with a pressure of 10 MPa, temperature of 100ºC and with a pressing time of 10 minutes. The evaluations of the results obtained were compared with the ANSI A208.1 / 2009 standard and with the literature on agglomerated panels of tropical species. In physical properties, the panels showed compliance with the values found in the literature, however, they are outside the standard of the norm. Regarding the mechanical properties, the MOR values classify the panels in the medium to high density standard in accordance with the standard. The results of the MOE are superior to those of the existing literature, with emphasis on the perpendicular traction that presents values consistent with the literature. The machining evaluations carried out according to ASTM D 1666-11 / 2011, show a good quality in the finish. In general analysis and in compliance with the regulations, all panels have economic viability and potential for industrialization.

Physical and Mechanical Characterization of Astronium Lecointei and Manilkara Huberi Branch Wood

Abstract Forest harvest residues are usable; however, studies on their quality are incipient. Thus, our study sought to perform physico-mechanical characterization of wood from the branches of Astronium lecointei and Manilkara huberi, as well as to compare its properties with trunk material found in the literature. The material was collected in the Tapajos National Forest (Flona - Tapajos) and cut for the trials performed at the Universidade Federal do Oeste do Para (Ufopa). Descriptive statistics were used for data analysis and the averages were compared with values found in the literature for the trunk of the studied species and other commercial wood of the region. The physical properties of Astronium lecointei and Manilkara huberi showed approximate averages to those of trunk, while the mechanical properties presented lower averages. Therefore, regarding the mechanical properties, the residues may be substituents for the trunks of other species for having similar properties.

Carbon fiber-reinforced polymers as a tensile reinforcement of the Pinus elliotti and Manilkara huberi wood species

In wood structures, the elements subjected to bending stresses, such as the beams, present a fracture initiated in the tensile region, and under these conditions, the use of laminated composite materials is presented as an alternative solution in the form of repair or reinforcement. This research aimed to evaluate the influence of the use of carbon fibers laminated composites in tensile reinforcement in the direction parallel to grain of Pinus elliotti and Manilkara huberi wood species. The Viapol two-component epoxy adhesive was used in the lamination and fixation of the unidirectional carbon fiber in the wood species. Ten specimens with no defects (reference) and 10 specimens were prepared for each crack length (25 and 50mm) with and without the reinforcement (60mm × 50mm) by the laminated composite. The tensile tests were performed in accordance with the requirements of the Brazilian standard ABNT NBR 7190 (1997). From the results of the statistical analysis, the use of the carbon fiber composite was able to restore the tensile strength of the cracked samples (partial or total) in relation to samples without defects, demonstrating the potential of the laminates in carbon fibers as an alternative solution in repair for both wood species.

CONICITY AND YIELD FOR LUMBER FROM COMMERCIAL SPECIES FROM THE AMAZON

ABSTRACT Stem conicity and the sawing pattern, besides the presence of hollows and sapwood, are among the principal factors that are responsible for the low yield of lumber from harvested wood in the Amazon. Therefore, the objective of this study was to analyze of logs and stem conicity, and its effect on yield of sawn wood from the species Handroanthus impetiginosus (Mart. ex DC.) Mattos, Lecythis lurida (Miers) S. A. Mori, Manilkara huberi (Ducke) Chevalier, Astronium lecointei Ducke and Couratari sp., which are currently the most important commercial species in the study area. The data used were obtained from six production units in the Tapajos National Forest, Para. The variables analyzed were conicity (obtained as a function of the difference between diameters at the base and top) between logs, DBH classes (diameter at breast height) and species, as well as yield (estimated using the Software MaxiTora) between logs and species. The majority of the species showed differences in conicity between logs, with the first log being the most conic, which was directly reflected by the lower yield for this log. There was a tendency of increase in conicity in the larger DBH classes, and differences in conicity and yield between species. The estimated yields were superior to the percent yields observed for Amazonian species in studies done using samples with similar characteristics. Therefore, it was concluded that conicity can vary between species, logs, and DBH classes, and is a characteristic that directly effects the yield of lumber. Furthermore, the incorporation of cutting templates represents an alternative for maximizing lumber yield.

Measures for sustainable forest management in the tropics – A tree-ring based case study on tree growth and forest dynamics in a Central Amazonian lowland moist forest

The conservation of tropical forests is recognized as one of the most important challenges for forestry, ecology and politics. Besides strict protection, the sustainable management of natural forests should be enhanced as a key part of the foundation for the maintenance of tropical rain forest ecosystems. Due to methodological reasons it has been complicated to attain reliable growth data to plan sustainable felling cycles and rotation periods. Tree ring analyses enable the estimation of growth rates over the entire life span of trees and their age as well as giving hints from forest dynamics in previous centuries. For tree ring analysis, stem disk samples were taken from three important commercial tree species (Cariniana micrantha, Caryocar villosum and Manilkara huberi) in the upland (terra firme) forests of the Precious Woods Amazon logging company near Itacoatiara, Brazil. Based on radiocarbon estimates of individual growth zones, the annual nature of tree rings was proven for the three species. Tree rings were measured and the results used together with height estimates to model diameter, height and volume growth. The age of the eldest tree, a C. micrantha, was 585 yrs with 165 cm in diameter. The species’ diameter increments range from 0.20±0.12 cm yr-1 to 0.29±0.08 cm yr-1. At first sight, this is considerably lower than increments reported from other Amazonian or African timber species. Considering the respective wood density there is no significant difference in growth performance of dominant timber species across continents. The interpretation of lifetime tree ring curves indicate differences in shadow tolerance among species, the persistence of individuals in the understory for up to 150 years and natural stand dynamics without major disturbances. Management criteria should be adapted for the measured growth rates as they differed considerably from the Brazilian standards fixed by laws (felling cycle of 25–35 years and a common minimum logging diameter of 50 cm). Felling cycles should be increased to 32–51 years and minimum logging diameters to 63–123 cm depending on the species.

Massaranduba Sawdust: A Potential Source of Charcoal and Activated Carbon.

This paper provides proof of concept that activated carbon (AC) may be readily produced using limited conversion methods and resources from sawdust of massaranduba (Manilkara huberi) wood, thereby obtaining value-added products. Sawdust was sieved and heat-treated in an oxygen-free muffle furnace at 500 °C to produce charcoal. The charcoal was activated in a tubular electric furnace at 850 °C while being purged with CO2 gas. Microstructural, thermal and physical properties of the three components: sawdust, charcoal and AC were compared by means of field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), density and water adsorption/desorption measurements. The resulting AC had a large surface area as measured by Brunauer-Emmett-Teller (BET) comparable to other such values found in the literature. The large surface area was due to pore development at the microstructural level as shown by FESEM. XRD illustrated that sawdust had a semi-crystalline structure whereas charcoal and AC evidenced mostly amorphous structures. TGA and DSC showed that AC had high reactivity to moisture compared to sawdust and charcoal.

Classificação fisiológica de sementes de maçaranduba quanto a tolerância à dessecação e ao armazenamento

The demand for native forest seeds has been increasing due to the production of seedlings, used in the recovery of abandoned and degraded areas, as well as reforestation zones. To properly conserve these seeds, however, one needs to understand their tolerance to desiccation and storage. Thus, the objective of this work was to classify Manilkara huberi seeds regarding desiccation tolerance and storage behavior. After processing and water content determination of the newly harvested seeds, they were submitted to the drying process, followed by germination tests. According to the results, it is concluded that the seeds of M. huberi are classified as recalcitrant because they do not tolerate the drying process and the storage at low temperatures. The species M. huberi belongs to the group of climax species.

Spectral analysis of amazon canopy phenology during the dry season using a tower hyperspectral camera and modis observations

The association between spectral reflectance and canopy processes remains challenging for quantifying large-scale canopy phenological cycles in tropical forests. In this study, we used a tower-mounted hyperspectral camera in an eastern Amazon forest to assess how canopy spectral signals of three species are linked with phenological processes in the 2012 dry season. We explored different approaches to disentangle the spectral components of canopy phenology processes and analyze their variations over time using 17 images acquired by the camera. The methods included linear spectral mixture analysis (SMA); principal component analysis (PCA); continuum removal (CR); and first-order derivative analysis. In addition, three vegetation indices potentially sensitive to leaf flushing, leaf loss and leaf area index (LAI) were calculated: the Enhanced Vegetation Index (EVI), Normalized Difference Vegetation Index (NDVI) and the entitled Green-Red Normalized Difference (GRND) index. We inspected also the consistency of the camera observations using Moderate Resolution Imaging Spectroradiometer (MODIS) and available phenological data on new leaf production and LAI of young, mature and old leaves simulated by a leaf demography-ontogeny model. The results showed a diversity of phenological responses during the 2012 dry season with related changes in canopy structure and greenness values. Because of the differences in timing and intensity of leaf flushing and leaf shedding, Erisma uncinatum, Manilkara huberi and Chamaecrista xinguensis presented different green vegetation (GV) and non-photosynthetic vegetation (NPV) SMA fractions; distinct PCA scores; changes in depth, width and area of the 681-nm chlorophyll absorption band; and variations over time in the EVI, GRND and NDVI. At the end of dry season, GV increased for Erisma uncinatum, while NPV increased for Chamaecrista xinguensis. For Manilkara huberi, the NPV first increased in the beginning of August and then decreased toward September with new foliage. Variations in red-edge position were not statistically significant between the species and across dates at the 95% confidence level. The camera data were affected by view-illumination effects, which reduced the SMA shade fraction over time. When MODIS data were corrected for these effects using the Multi-Angle Implementation of Atmospheric Correction Algorithm (MAIAC), we observed an EVI increase toward September that closely tracked the modeled LAI of mature leaves (3–5months). Compared to the EVI, the GRND was a better indicator of leaf flushing because the modeled production of new leaves peaked in August and then declined in September following the GRND closely. While the EVI was more related to changes in mature leaf area, the GRND was more associated with new leaf flushing.

Does masting result in frugivore satiation? A test with Manilkara trees in French Guiana

Abstract:Species showing mast seeding synchronously produce large amounts of fruits during some scattered years. This massive crop has been hypothesized to improve dispersal effectiveness by a satiation of seed predators, but the consequences for seed dispersers have barely been studied in the tropics. We tested the hypothesis that masting resulted in satiation of frugivorous dispersers using the study case of two Manilkara species growing in an Amazonian forest in French Guiana. Seed dispersal was estimated by means of seed traps in two forest types during a 10-y monitoring. Manilkara huberi and M. bidentata showed three fruiting events in a time span of 10 y (in 2001, 2006 and 2010). Estimates of seed dispersal from 2001 and 2010 showed that satiation of frugivores only occurred in the year with the largest crop of Manilkara (2010) and in the habitat where the diversity of primate-dispersed species retrieved in seed traps was the highest (Grand Plateau, with clay soils), while fruit consumers did not seem to be satiated in other instances. Spatio-temporal variability of seed production and the community-crop context are therefore affecting satiation of frugivores during masting events.

Decayed Wood Affecting the Attraction of the Pest Arboretum Termite Nasutitermes corniger (Isoptera: Termitidae) to Resource Foods

Nasutitermes corniger shows preferential feeding for the wood of different tree species, but it is not known whether attractiveness is a function of the state of decay. This study examined the foraging behavior of N. corniger towards wood in different stages of decay. Wood was exposed to weather for durations of 0, 3, 6 or 9 months. Then the wood was placed in a standard foraging arena with termites. Exploration and recruitment behavior were recorded for 1 h. Separate bioassays were conducted for three species: Pinus elliottii, Eucalyptus grandis and Manilkara huberi. In the tests with P. elliottii and E. grandis, more individuals were recruited to wood decayed for 6 months (191 and 185, respectively) than to undecayed wood (12 and 69, respectively). Similarly, more individuals were recruited to decayed M. huberi wood than undecayed, but only after 9 months (249 and 7, respectively). Decayed wood has therefore been demonstrated to be more attractive to N. corniger than undecayed wood. The different decomposition rates necessary to increase attractiveness may be explained by differences in wood density.

Níveis de regeneração natural em floresta de terra firme no Amapá Brasil

Este trabalho objetivou identificar a regeneração natural na fitofisionomia ombrófila densa da Floresta Estadual do Amapá, descrevendo as relações entre estratos verticais. A área de estudo está localizada no Município de Porto Grande, AP, Amazônia oriental. Foram implantados três conglomerados, equidistantes 2.500 m, para a estimativa da regeneração natural. Foram utilizadas 100 subparcelas de 10 x 10 m para o estudo das arvoretas (5,0 < dap (diâmetro a 1,30 m do solo) < 10,0 cm) e varas (5 x 5 m) (2,5 < dap < 5,0 cm) por conglomerado. Coletaram-se as alturas e nomes populares. As alturas foram divididas em três classes de regeneração, para a estimativa dos parâmetros fitossociológicos de frequência e densidade, bem como da regeneração por classe de tamanho e total. A diversidade foi estimada pelo Índice de Shannon. Também, analisou-se a similaridade florística entre as varas e arvoretas por conglomerado. O inventário contemplou 2.700 indivíduos, pertencentes a 38 famílias botânicas, 93 gêneros e 141 espécies arbóreas, com seis indeterminadas. O índice de Shannon foi de 4,21 (arvoretas) e 4,11 nats.ind.-1 (varas). Foi constatada a ocorrência de 33 espécies comuns nas três classes de regeneração. A regeneração natural total apresentou variações de 10,3 a 0,1% (varas) e 5,6 a 0,1% (arvoretas). As espécies com menores percentuais foram as Indeterminadas, Vouacapoua americana, Carapa guianensis, Virola calophylla e Manilkara huberi. Logo, fica evidente que as espécies estão desenvolvendo seu processo sucessional de forma eficiente, garantindo a conservação da fitofisionomia da região.

Disturbance Level Determines the Regeneration of Commercial Tree Species in the Eastern Amazon

AbstractThe effects of reduced‐impact logging (RIL) on the regeneration of commercial tree species were investigated, as long‐term timber yields depend partly on the availability of seedlings in a managed forest. On four occasions during a 20‐month period in the Tapajós National Forest (Eastern Amazon, Brazil), seven commercial tree species were assessed as follows: the long‐lived pioneers Bagassa guianensis and Jacaranda copaia; the partially shade‐tolerant Hymenaea courbaril, Dipteryx odorata, and Carapa guianensis; and the totally shade‐tolerant Symphonia globulifera and Manilkara huberi. In 2439 10 × 10 m plots, all individuals < 20 cm diameter at breast height (dbh) were assessed over three intervals, before, during, and after the forest being logged. Before logging, the density of seedlings and saplings of the seven species did not change. Logged trees were spatially aggregated, with 9.2 percent of the plots being heavily impacted by logging. After logging, the recruitment rate increased more than the mortality rate, so that post‐harvesting densities of seedlings and saplings increased. The increase in density was concentrated in logged plots with more disturbances. It is concluded that post‐harvesting heterogeneity of micro‐environments created by RIL may be an important component to be taken into account for sustainable forest management and conservation of commercial species.