Caribaea Var Research Articles

DOES RESIN TAPPING AFFECT THE TAPERING AND ACCUMULATION OF MERCHANTABLE TIMBER VOLUME IN PINE TREES?

Form factors and taper functions are used for the quantitative and qualitative description of tree stem shape. In southeastern Mexico, there are plantations of Pinus caribaea var. hondurensis (Sénécl.) W.H. Barrett & Golfari, Pinus elliottii var. elliottii Engelm., and hybrids between these species to simultaneously produce resin and wood. Farmers need to know whether the practice of resin tapping to death has a negative impact on tree shape and volume of the wood produced. To answer these questions, this study compared the shape, taper, and volume of resin-tapped and untapped trees from three P. caribaea origins. A total of 198 trees (99 resin-tapped and 99 untapped) were measured in all diameter categories of the plantation. Total volume models, along with a compatible taper system and variable merchantable timber volume, were fitted using linear and nonlinear regression analyses. To compensate for the lack of initial tree size data prior to tapping, indicator variables (dummies) and an additive structure were used to parameterize volume and taper models. Untapped trees accumulated greater volume than tapped trees. In contrast, the form factor (ff) of resin-tapped trees (ff = 0.51) was greater than that of untapped trees (ff = 0.45). The form factor increased due to tapping between 4 and 7 % depending on the origin, although the hybrid P. caribaea × P. elliottii presented the most desirable stem geometry in tapped and untapped trees. Based on the Demaerschalk model, the variability is estimated at 99 and 97 % of the merchantable and taper volumes, respectively.

Funciones alométricas de altura total para pinos tropicales en Puebla, México

Tropical pines are important because of the amount of wood they produce in short periods. However, it requires allometric functions to predict the total tree height, since it is one of the critical variables to estimate both, it is the total and commercial volume. Accordingly, we aimed to develop a local and a generalized allometric function for model the total height-diameter (h-d) relationship of Pinus caribaea var. hondurensis and hybrid Pinus caribaea var. hondurensis × Pinus tecunumanii in the Sierra Norte of Puebla, México. In order to analyze the relationships, 1 232 h-d pairs were used. The allometric models were fitted with three parameters totaling 80% of the data and validated with 20%. The best model had the lowest average bias, root mean square error, and Akaike’s Information Criterion, as well as of the highest adjusted coefficient of determination. The models explained over 58.55% of the variability in observed total tree height. Nonetheless, the Gompertz and Weibull models obtained the best performances in fit and validation, and estimated h of tropical pines with less uncertainty. In consequence, the fitted allometric functions are reliable for predicting tree h; therefore, it can contribute to the sustainable management of commercial tropical pine plantations in the study region.

Apparent density of wood determined by two different methods in Pinus caribaea var. hondurensis and Pinus tecunumanii

The aim of this study was to compare the apparent wood density obtained by two different methods in populations of Pinus caribaea var. hondurensis and Pinus tecunumanii, both 50 years old, located in Itirapina, SP. For this purpose, five trees of each species were selected. From each tree, two discs of 7 cm thickness were removed in the diameter at breast height (DBH) region. To determine the apparent density by the gravimetric method, samples were collected at five different positions, from pith to bark, on one of the discs. The other disc was used to obtain the radial profile of apparent wood density, using the X-ray Densitometry method. The results revealed that the apparent density did not differ significantly between the species. Variations in apparent density were observed from pith to bark in the trunks of both species, with a tendency of increasing density towards the bark. Furthermore, positive correlations between radial position and apparent density were observed in both species. The methodologies used to obtain the apparent density showed a high correlation between them, allowing for estimates with good precision. It is worth noting that the apparent density obtained by the gravimetric method showed significantly higher values than the X-ray densitometry method.

Predicting Wood Density Using Resistance Drilling: The Effect of Varying Feed Speed and RPM

The IML PD series Resi is a device used to assess the drilling resistance of wood. The IML PD series Resi instrument is being widely adopted for commercial wood quality assessment due to its speed, cost-effectiveness, and precision when combined with web-based trace processing. Collecting Resi data with fixed feed speed and RPM settings is challenging due to inherent basic density variations within and between tree species. Altering these settings affects the drilling resistance amplitude of the Resi data, impacting basic density predictions. This study introduces the concept of chip thickness to combine feed speed and RPM into a single parameter to minimise the effects of different sampling conditions on the basic density predictions. Regression models, with chip thickness as the regressor variable, account for 97% to 99% of variance in mean Resi outerwood amplitude across six species. The demonstrated adaptability of chip thickness for adjusting feed speed and RPM settings, along with species-specific functions correlating it with Resi amplitude, holds promise for standardizing amplitude values across diverse feed speeds and RPM settings. Optimal sampling conditions needed to predict basic density lie within the 30%–40% amplitude range. To drill a ~30 cm diameter tree, the recommended fastest settings were 200 cm/min and 3500 RPM for Southern Pine (Pinus elliottii var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Sénéclauze)) and Radiata Pine (Pinus radiata (D. Don.)), 200 cm/min and 2500 RPM for Hoop Pine (Araucaria cunninghamii (Mudie)), 50 cm/min and 5000 RPM for Spotted Gum (Corymbia citriodora subsp. variegata (F. Muell.)), 200 cm/min and 4500 RPM for White Cypress (Callitris glaucophylla (Thompson & Johnson)), and 150 cm/min and 3500 RPM for Shining Gum (Eucalyptus nitens (H. Deane & Maiden) Maiden) based on the billets sampled.

Predicting Wood Density Using Resistance Drilling: The Effect of Instrument and Operator

The IML PD series Resi is an instrument designed to measure the drilling resistance of wood. Use of the IML PD series Resi instrument is rapidly becoming a routine method among Australian forest plantation growers for wood quality assessments. The major driver in the commercial uptake of the IML Resi is that it is fast, cheap, and sufficiently precise for commercial use, particularly when the data are processed through a user-friendly, web-based processor. This study examined whether the accuracy of wood density predictions was impacted by the use of different Resi tools and different operators, which has never been examined before. Seven Resi instruments were evaluated across six sites with two operators on plantation-grown Southern Pine (Pinus caribaea var. hondurensis (Sénéclauze) or hybrids between Pinus elliottii var. elliottii (Engelm) × P. caribaea var. hondurensis) trees. Two types of Resi instruments were used (IML Resi PD-400 and IML Resi PD-500), and all had been recently serviced or were new. The instruments were operated by experienced operators. Constant sampling conditions of feed speed 200 cm/min and 3500 RPM were used. The order of instrument use, and hence the order of operator assessment at each site, was randomized. The variance between Resi instruments was small. The measured mean basic density of 50 mm outerwood cores across all plots was 542 kg/m3, while Resi-predicted basic density varied among instruments between 535 and 547 kg/m3. One Resi instrument underpredicted basic density by 9 kg/m3 and another overpredicted by 5 kg/m3. The operator had no effect on the basic density prediction. Resi PD400 or PD500 instruments gave similar basic density predictions.

Climate-growth relation and isotopic △13carbon responses of field-grown Pinus caribaea var. hondurensis and Pinus taeda to nutrient availability

This study aimed to characterize the development of Pinus caribaea var. hondurensis and Pinus taeda grown under two fertilization regimes (fertilized and control treatments) at field-grown condition. The growth, climate-growth relation, and intrinsic water use efficiency (WUEi) of the trees were assessed by a combined analysis of cross-sectional area (CSA) increment, water balance and carbon isotope discrimination (Δ13C ‰). The effect of fertilization on tree growth regime was assessed using inventory data collected yearly over 8 years. Additionally, monthly data of wood increments, monitored in nonfertilized stands over a period of 6 years, were utilized for correlations with meteorological variables (air temperature, rainfall, vapor pressure deficit, solar radiation and potential and actual evapotranspiration). The growth of Pinus caribaea and P. taeda was strongly influenced by multiple meteorological variables related to water availability and evapotranspiration. Differences in carbon isotope composition between treatments revealed that fertilized Pinus spp. displayed higher Δ13C values in some years, indicating improved water uptake efficiency due to increased nutrient availability. Pinus caribaea outperformed P. taeda in wood productivity and exhibited a heightened responsiveness to fertilization. In general, P. caribaea was shown to be more water-use efficient than P. taeda, as it is able to use smaller amounts of water for greater wood production.

Evaluation of the Oriented Strand Board Properties Produced Using Tropical Wood Mixtures

The objective of this study was to evaluate the composition of OSB panels created using the Amazonian species Caryocar villosum Aubl., Erisma uncinatum Warm., and Hymenolobium excelsum Ducke. The OSB was produced using a phenol–formaldehyde adhesive at a ratio of 30:40:30 for each layer. Different mixtures of Amazonian wood and Pinus caribaea var. caribaea. were tested. Physical (water absorption and thickness swelling after 2 and 24 h of immersion in water and non-return rate in thickness) and mechanical (internal bond and parallel and perpendicular static bending) tests were performed. The OSB panels composed of wood mixtures absorbed less water after 2 and 24 h of immersion when compared to the OSB produced using pine wood. After 24 h of immersion in water, the T3 panel (40% Pinus caribaea + 40% Hymenolobium excelsum + 20% Caryocar villosum) presented the lowest absorption value. In terms of swelling in thickness at 2 h and 24 h, the panel composed of 100% pine strands showed the highest swelling value, while the T3 treatment exhibited the lowest swelling value at 2 and 24 h, as well as for the rate of non-return in thickness. Regarding mechanical properties, we observed that all panels exhibited similar resistance for both parallel and perpendicular Modulus of Rupture, as well as parallel and perpendicular Modulus of Elasticity, except for the internal bond, where T3 demonstrated the highest resistance. Additionally, some OSB panels met the requirements of the EN 300 standard for OSB panels.

Modeling the growth and production of Pinus Caribeae Var. Caribeae not thinned in Mato Grosso state

The objective of this work was to evaluate the growth and production through statistical models, under the variables of diameter at 1.30m, total height and volume of a stand of Pinus caribaea var. caribaea at 35 years old, not thinned, located in the municipality of Nova Marilândia, Southwest region of the state of Mato Grosso. Diameter data at 1.30m high and total height data were collected in 31 temporary plots with 900 m² (30m x 30m) and 60 dominant and codominant trees were felled. Of these, 31 were rigorously scaled using the Smalian method and trunk analysis was performed in 29. Fourteen volume equations, local productivity classification were adjusted, in addition to the adjustment of nine growth and forest production models. The accuracy verification of the estimates of all the models tested was given by the adjusted Coefficient of determination (R²adjus.); the Standard error of estimates (Syx%); and the Error percentage (Error%) and graphic analysis of residues. To determine the volume of Pinus caribaea var. caribaea, the best adjustment was obtained with the Schumacher-Hall model. The growth and production models suitable for P. caribaea for the diameter estimates were Hoerl's, and for height and volume were Moissev's. In the classification of local productivity, 3 site classes were determined, ranging between 18 and 26 m at the index age of 35 years with the Moissev model.

Alvania skylla n. sp. from the Mediterranean Sea (Gastropoda: Rissoidae)

A new Mediterranean species of the genus Alvania Risso, 1826 is described: Alvania skylla n. sp. The new species has been collected in the Central and Western Mediterranean Sea (Sicily, Malta, Tyrrhenian Sea and Ceuta) at 20–90 m depth. In the literature, it has been reported as A. subareolata Monterosato, 1869, from which it differs for the bi-angulate whorl profile, the much stronger ribs and spiral cords forming acute tubercles at crossings. The spiral cords are in number of two (rarely three), instead of always three. Axial ribs are less numerous (12–16 against 18–23). The labial varix is much stronger and larger, with the cords passing over it. When seen from the side the labial varix is straight instead of slightly sinuous. The characteristics of A. subareolata living in Sicily and Western Mediterranean are compared. The relationship with Rissoa ignorata Pallary, 1920 from the Atlantic coast of Morocco is discussed. The new species is compared with Alvania guancha Moolenbeek & Hoenselaar, 1989 from the Canary Islands. Rissoa areolata Philippi, 1844 is here considered nomen dubium, while Rissoa caribaea var. asperrima Monterosato, 1873 is considered nomen nudum.

Maximizing the Use of Out-of-Grade Hybrid Pine in Engineered Wood Products: Bond Performance, the Effect of Resin Streaking, Knots, and Pith

The evolution toward small-diameter and fast-growing plantation timbers such as the Pinus elliotti var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Sénéclauze) (PEE×PCH) hybrids around the world is producing large volumes of core wood that are falling short of structural sawn timber grading requirements. Engineered timber products such as cross-laminated timber (CLT) and glue-laminated (glulam) offer potential solutions to value-adding this resource, but the bond performance of this feedstock and the extent to which current standards and guides address its common characteristics for bond performance need to be understood. This study investigated the bond quality and performance of clear defect-free, low stiffness out-of-grade PEE×PCH and evaluated this performance using the pass/fail criteria of the CLT bond performance requirements of three national CLT standards. 5-layer CLT delamination samples and shear block test samples were glued using one-component polyurethane (PUR). This process was repeated for common occurring characteristics in this resource of resin, knots, and pith to understand their impact and inform an evaluation on the need to restrict their inclusion. Clear samples had an average glue line delamination of 2.9% and an average glue line wood failure of 96.7%. Resin achieved 9.3% and 92.6%, respectively. While knots had the lowest performance at 24.4% and 77.4%, respectively. When pith was at or adjacent to the glue line, wood failure occurred through the pith and its immediate surrounding fiber. Shear strength and wood failure tests were carried out on glulam and CLT-oriented samples. CLT knot samples were tested in two load orientations. Glulam-oriented samples in clear, resin, pith, and knots achieved an average shear strength of 8.5 MPa, 8.2 MPa, 7.9 MPa, and 8.2 MPa, respectively, and wood failure of 86%, 85%, 90%, and 69%, respectively. CLT-oriented samples in clear and resin both achieved average shear strengths of 4.0 MPa; 0°-loaded and 90°-loaded pith samples achieved 3.6 MPa and 2.4 MPa, while 0°-loaded and 90°-loaded knot samples achieved 4.2 MPa and 4.7 MPa respectively. Average wood failures were 90%, 89%, 96%, 96%, 83%, and 51%, respectively. PRG320 was found to be the most restrictive standard. Resin, knots, and pith were not addressed in the evaluation of delamination or shear strength in any standard, and PRG320 was the only standard to restrict these characteristics over and above structural grading rules. The amount and type of characteristics present vary considerably in structurally graded wood, and even more so for this out-of-grade resource. It was determined that the negative impact that resin, knots, and pith have on bond quality and bond performance calls for some restriction of their inclusion in order to achieve the author’s interpretation of the intended bond performance requirements of the CLT standards, which currently do not address these characteristics well or at all. A proposed modification to the PRG320 effective bond area was presented as a proactive solution.

Physical and mechanical wood properties of two varieties of Pinus caribaea

This study aimed to characterize the properties of wood from Pinus caribaea var. hondurensis and Pinus caribaea var bahamensis, in 7-year-old individuals, in the municipality of Batatais, State of São Paulo, Brazil. For this, twelve trees of each species/variety were felled, and a 1 m long log was removed from the base of each tree. Samples were taken from the obtained logs to evaluate the physical-mechanical properties of the wood. It was verified that the woods of Pinus caribaea var. hondurensis and Pinus caribaea var. bahamensis do not differ significantly from each other for: Apparent density, basic density, compression parallel to the grain, shear parallel to grain, modulus of elasticity, volumetric shrinkage, anisotropy coefficient, radial shrinkage, and tangential shrinkage. The wood of the species/variety Pinus caribaea var. bahamensis showed a significantly higher modulus of rupture than the variety Pinus caribaea var. hondurensis. Regarding the use of wood from these species/variety, at a younger age, both showed potential use for different purposes. Since this initial assessment can be used as an indication of pre-selection of wood for the various segments of the timber industry, mainly for uses that do not have many restrictions in structural applications and dimensional variation.

COLORED AREA, GROWTH-RING WIDTH, AND LATEWOOD PERCENTAGE IN HYBRID PINE F1 INTA-PINDO

The characteristics of the annual growth rings are indicators of the growth and quality of the wood. At 11 years of age, 90 F 1 hybrid pine trees of Pinus elliottii x Pinus caribaea var. hondurensis were sampled from two sites. The sample consisted of 15 families and 3 positions in the genetic growth ranking. Disks were taken at 0.10 m, 1.30 m, and 4.45 m, colored area (%) in the central zone of the log, ring width, growth-ring area, and proportion of latewood were evaluated. The data were analyzed with mixed linear models. Statistically significant differences were found between families for the studied variables, except for latewood percentage. Family 02 showed higher growth and a low proportion of pink core. Families 01 and 03 had a higher percentage of colored area. The percentage of colored area increased with tree height. The ring width decreased with tree height and was higher for families 01, 02, 03, 04, 05, and 07. The latewood percentage increased from the pith to the bark and from the tree base to the crown. To conclude, top-growth families exhibited higher mean ring width and ring area than lower-growth families but the same proportion of latewood. These are desirable characteristics for obtaining wood quality for structural uses.

Genetic Control of Pitch Canker Response in Southern Pine and Southern Pine Hybrids

Fusarium circinatum causes pine pitch canker (PPC) disease and associated symptoms such as resinous lesions, mechanical weakness, and crown dieback that may lead to mortality in Pinus and Pseudotsuga spp. There are no ameliorative techniques available for the disease, and the genetic resistance among populations to support commercial plantation deployment has not been well characterized. In this study, we characterize the genetic control of PPC disease tolerance (and/or resistance) and predict the tolerance of families in existing breeding populations: open-pollinated (OP) half-sib and control-pollinated full-sib (FS) slash pine (Pinus elliottii var. elliottii Engelm.), OP loblolly pine (Pinus taeda L.), and advanced-generation OP hybrid slash × P. caribaea (Pinus elliottii var. elliottii Engelm. × Pinus caribaea var. bahamensis, caribaea, and hondurensis) using F. circinatum isolates obtained from three locations in Georgia and FL, USA. We describe a new experimental design that improves the accuracy of breeding value predictions, provides more precise genetic parameter estimates, and facilitates comparisons within and among taxa as well as comparisons among isolates. We found strong evidence for genetic control of the ratio of stem damage by F. circinatum, especially in slash pine and slash × P. caribaea hybrids. Loblolly and slash × P. caribaea hybrids exhibited less damage than slash pine. We observed a spectrum of virulence among F. circinatum isolate sources, which were not equally virulent in different pine taxa.

Analysis of genetic diversity in two plantations of <i>Pinus caribaea</i> var. <i>hondurensis</i>

Forest tree breeding activities in plantations with exotic species implies several instances of material selection where genetic variation can be affected. The objective of the work was to verify the genetic variability present in two plantations of Pinus caribaea var. hondurensis by microsatellite markers, initially designed for Pinus taeda fluorescent-labeled. Thus, 299 individuals were analyzed using eight polymorphic microsatellite markers. The results indicate that both plantations have adequate levels of genetic diversity that are representative of the Pinus genus. Through the Bayesian method, it was possible to detect two different population genetic structures (K = 2) between both plantations analyzed. In conclusion, this study suggests that microsatellites markers are useful tools to monitor genetic variation in genetic breeding programs. The genetic diversity estimated in both plantations is similar and typical for Pinus plantations, and as expected, there was a slight decrease in genetic variability in the commercial plantation in comparation with the base plantation.

Changing use of species and hybrids in South African forest plantations

South Africa has 1.2 million hectares of plantations developed progressively through the 20th century. These occur from 23° to 34°S, from near sea level to 2 000 m above sea level and in both Mediterranean winter rainfall and summer subtropical rainfall climates. Plantations supply pulp mills, sawmills, treated pole and mining timber production, and wattle tannin production. The diversity of sites and markets requires planting of a range of taxa of pine, eucalypt and wattle. A survey of planted area by taxa in South African forest plantations is reported and compared to statistics available from national annual reporting on the commercial timber resources in the country. The survey found a similar number of taxa are currently planted (15) as in the 1950s but only 6 of the earlier options remain in use. Changes have occurred in the last 30 years, with 40% of planted area in 2019 using options not available before 1990. From the 1990s, Eucalyptus grandis has been extensively replaced by eucalypt hybrids and E. dunnii and Pinus elliottii × P. caribaea var. hondurensis has become an important pine planting option. Over the past decade, E. nitens replacement with other existing frost tolerant eucalypt planting options has occurred, use of P. radiata has reduced and P. patula has been replaced on a significant scale with P. patula hybrids. Many of these changes have been to mitigate the impact of new pests and pathogens and, on lower productivity sites, periodic severe droughts. However, the new planting options also provide increased yields and have wood properties acceptable to the intended markets. Meeting all three criteria is likely to remain a requirement for successful introduction of future new planting options. The survey indicates a need to revise current national reporting requirements to better reflect use of species and hybrids in South African plantations.

Longitudinal analysis of Pinus caribaea var. hondurensis full-sibling progenies based on multivariate analysis

Aim of study: To define an early selection strategy based on tests applied to full-sibling progenies of Pinus caribaea var. hondurensis grown in the Cerrado Biome.
 Area of study: Prata region (MG), Brazil.
 Material and methods: Progeny tests were cultivated in 2006; the study followed a completely randomized design, with 79 families of full-siblings and 15 repetitions, with one plant per plot. Thinning was carried out at the age of 6 and 8 years; 615 individuals and 44 families were included in the test. The following quantitative variables were used in the statistical analysis of data on the remaining individuals: diameter at breast height (DBH) in cm, total height (H) in m, and volume in dm³ at the age of 3, 4, 5, 6, 7, 8 and 11 years. BLUP multi-trait multivariate model, with non-structured covariance structure matrix, was adopted for calculations.
 Main results: There were strong additive genetic correlations (above 90%) between variables DBH and H, in all analyzed ages. Strong volume correlations were estimated based on the age group over four years; volume selection efficiency reached its peak at the age of five years. Selection based on volume at the age of 5 years leads to genetic gains in this variable; selection intensity values can range from 7.8% to 6.4% and 5.4%, and from 10% to 20% and 30%.
 Research highlights: The best strategy lies on carrying out the selections at the age of five years, based on 30% selection intensity.

Mechanical Properties of Low-Stiffness Out-of-Grade Hybrid Pine—Effects of Knots, Resin and Pith

Out-of-grade pine timber is an abundant material resource that is underutilised because its mechanical properties are not well understood. Increasing trends toward shorter rotation times and fast-grown plantation pines around the world such as Pinus elliottii × P. caribaea var. hondurensis hybrid (PEE × PCH) mean low-stiffness corewood is becoming a larger portion of this out-of-grade population. This study characterised the modulus and strength properties in bending, compression parallel to grain (CParG) and compression perpendicular to grain (CPerpG), shear and tension strength of low-stiffness out-of-grade PEE × PCH. The effect of resin, knots and pith on these properties were also investigated. The results show that in clear wood, the MOE in bending, CParG, CPerpG and shear modulus are 6.9 GPa, 5.78 GPa, 0.27 GPa and 0.59 GPa, respectively, while strengths are 45.8 MPa, 29.4 MPa, 6.7 MPa, 5.7 MPa, respectively. The tensile strength is 32.4 MPa. Resin significantly increased density 45% higher than clear, but performed similar with the exception of CPerpG MOE and strength which were significantly different. Resin area ratio (RAR) has a moderate correlation with density with an R2 of 0.659 but low to no correlation for mechanical properties. Knots were significantly different to clear for all test types and within a range of 48% to 196%. Knots were high in CPerpG MOE and strength but lower for all other properties and had the largest negative impact on tensile strength. Knot area ratio (KAR) had low to moderate correlation with tension strength and CPerpG MOE with R2 of 0.48 and 0.35, respectively. Pith was within the range of 76% to 121% of non-pith samples for structural performance, some of which were significantly different, and pith samples were higher in density than non-pith. This new information is crucial for the effective establishment of grading rules, design optimisation and utilisation of low-stiffness out-of-grade PEE × PCH as a new material resource in civil engineering applications.

Initiation of somatic embryogenesis in Pinus caribaea var. hondurensis using mature female gametophytes as explants

Due to the difficulties of harvesting immature cones in genetic breeding orchards, such as high costs and the considerable time required, this study aimed to evaluate the somatic embryogenesis (SE) initiation of Pinus caribaea var. hondurensis using the mature female gametophyte as the initial explant. The basic medium for embryogenesis initiation was composed of QL (Quoirin and Lepoivre, 1977) nutrients, sucrose, myo-inositol, glutamine, casein hydrolisate, thiamine, 2,4-D, BAP and agar. This medium was compared with DCR (Gupta and Durzan, 1985) and WV5 (Coke, 1996) media, supplemented or not with 0.1 g L−1 folic acid (FA). Afterwards, three concentrations of 2,4-D (10, 20 and 30 μM) combined or not with BAP (2, 4 and 8 μM) were tested. After 90 days the percentages of explants with embryogenic tissue (ET), embryo-like structures and oxidation were evaluated. We observed somatic tissue initiation` on mature female gametophytes. On QL medium supplemented with FA, the initiation was observed on up to 42% of female gametophytes. The combination of 10 μM 2,4-D and 4 μM BAP resulted in the highest initiation rate. The formation of ET was confirmed in all treatments by a histochemical test. Embryo-like structures developed on QL medium supplemented with FA, were first transferred to basic medium supplemented with 1.5 g L−1 AC for 30 days and finally to the same medium supplemented with 10% polyethylene glycol 3350 and 120 µM abscisic acid. The expression of SERK-1 and GER-1 genes was analyzed. SERK-1 was expressed only in the ET, while GER-1 was expressed in both the embryogenic and non-embryogenic tissues (non-ET). However, the somatic embryos studied through morphological and histochemical tests proved to be abnormal and did not develop further.

Investigating the generation of wood wastes from mechanical processing of two forest species

The circular saw is a tool commonly used for wood processing. It may be presented at different models. Considering their specificities, they can generate different amount of waste. The objective of this study was to evaluate the generation of waste from Tectona grandis L. f. and Pinus caribaea var. hondurensis, processed with two saws of the multiple type (48 and 36 teeth) and one of the universal type (28 teeth). The cutting process followed in grain direction into ninety samples, 15 for each species and saw, until the sample was completely processed. The processing time was measured and the waste was collected in each operation. ANOVA and test of multiple comparison of averages were applied. The influence of the teeth number and type of saw on the amount of waste generated was verified. The universal saw was the one that generated the highest amount of waste. It reached up to 116% more than the multiple saw, that generated the lowest amount of waste (36 teeth). P. caribaea var. hondurensis generated 7% more waste and presented shorter processing time (22%), when compared to T. grandis.

Landscape heterogeneity increases survival of Pinus caribaea var. hondurensis juveniles in a frequently burned, humid savanna

AbstractWe characterized Caribbean pine (Pinus caribaea var. hondurensis) seedling and juvenile survival in lowland Belizean savannas with respect to environment and fire regimes. Plants in open and densely wooded environments had lower survival after fire. We hypothesize that facilitative or correlative mechanisms might promote positive relationships between shrubs and pine survival.Abstract in Spanish is available with online material.