Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

A n evaluation of different sampling plot sizes was carried out on a Pinus cooperi Blanco stand in the region of El Salto, Durango, Mexico to determine optimal plot size for forest inventory.  A complete census was carried out in a 4.4 ha area and 36 plots of 0.1 ha were established. Plot sizes of 0.01 to 0.1 ha, with intervals of 0.01 ha were tested using a fixed dimensions plot simulator. Based on the statistical parameters of the basal area, optimal plot size was 0.06 ha.

An empirical method to calculate the volume of small samples of wood obtained with an increment borer, for the purpose of estimating specific gravity, was evaluated. The empirical method was compared with other methods commonly used: the water displacement method and the maximum moisture method. The mean values, standard deviation, specific gravity minimum and maximum obtained with the empirical method w ere significantly correlated with those values obtained with the other two methods. This indicates that the empirical method is a reliable option, as well as being faster and simpler, for estimating the specific gravity of small samples of regularly shaped wood.  

This study presents the results of a taxonomic review of the conifers found in the La Michilía Biosphere Reserve in southeastern Durango, México. Two families with 13 taxa, including infraspecific levels, were identified.  The Cupressaceae family is represented by the genus Juniperus with two species and one variety and the genus Cupressus, with one species. The Pinaceae family is represented by Pinus with nine species and one variety, and one species of Pseudotsuga. A dichotomic key for species identification is included, as well as descriptions, geographical distribution, and references to the specimens examined.

Some studies focus on the analysis of the effect of mineral fertilization on variables associated with tree growth in productive plantations. They mainly analyze the short-term response to fertilization. The aim of this research is therefore to analyze the long-term response to mineral fertilization, applied fractionally over the first five years of the establishment of a Pinus caribaea plantation in Viñales, Pinar del Río, Cuba. The effect on growth, in diameter and height, was examined using a randomized block design. Seven treatments were established, according to the doses and application regime of NPK, as well as a control, with no fertilizer. These variables were measured at different ages, in 288 trees over 41 years and the growth functions were estimated using a multilevel regression for the entire period and in two separate stages. The analysis of the coefficients for the obtained growing curves showed that, in the period from 2 to 41 years, the diameter and height for individual trees were, on average, superior to those of the control, in treatments of 600 g, 800 g and 1000 g of Nitrogen, Phosphorus and Potassium (NPK) per tree. Treatment with application of a single dose of 300 g of Nitrogen, Phosphorus and Potassium (NPK) tree-1 produced lower values of diameter and height than those of the control. The two-stage study demonstrated that, from 33 to 41 years, homogeneity in height was achieved among treatments, except for the treatment with 300 g of (NPK) tree-1, which presented lower heights relative to those of the control.

A forest tree health can be accurately assessed by evaluating foliage biomass; even when it represents only 4% to 6% of the total tree biomass, it is the main driver of every major physiological processes. This research was mainly focused on estimating accurately needle biomass at branch and tree level on fast growing trees of Pinus patula Schl. et Cham. Needle biomass per branch was estimated with a linear model, which used live branch basal area, live branch height, and crown section like independent variables.Above ground components were estimated with determination coefficients of 0,86, 0,92 and 0,88 for wood with bark, branches and needles. For the wood with bark model, diameter at breast height(DBH) and total tree height (HT) were used in a linear structure; total branch biomass was fitted with a non-linear model, using live crown diameter (LCD) and crown area (CA) while total needle biomass used LCD and HT on a non-linear model. The aboveground total biomass per tree was estimated with R2 = 0.87, using DBH and HT. At 14 years old, biomass partition was estimated to be 92,9%, 4,7% and 2,4% for wood with bark, branches and needles, respectively.

The temperate forests of Chipinque Ecological Park (PECh) are of great importance due to environmental services they provided to the Metropolitan Area of Monterrey. In 1998 was raised a forest fire that affected the third part of the PECh. In the area post-fire was performed an ecological restoration program. In 2008 (ten years after) was conducted a comparative analysis of the diversity of the arboreal component of the restored area and naturally regenerated. The objective was to determine whether there are statistical differences in tree diversity (number and species density, and vertical and horizontal structure) between the two areas. By means of species-area curve was determinated the establishment of four sampling units of 100 m2 in each area. Were 8 families, 10 genera and 14 species. The genus with more presence in both areas was Quercus. The second specie more important in restored area was Pinus pseudostrobus. According to vertical analysis of arboreal layer was concluded that both areas are multicohorts. Referring to ß diversity the evaluated areas presented a mediumhigh similarity. The restored area and regenerated not present statistical differences in the diversity-abundance (t= 0 ,55, g.l.=1269,63, p<0,05), abundance (t=0,16) and dominance (t=0,26). This research generated quantitative information that indicates that the silvicultural practices employed for ecological restoration increased the density of P. pseudostrobus, without altering the diversity, abundance and dominance of the trees.

Tropospheric ozone has been suspected to cause poor vitality and occasional massive mortality in sacred fir (Abies religiosa ( Kunth) Schltdl. & Cham) from Desierto de los Leones National Park, in Mexico City, Mexico, since 1980`s. This work searches for empirical evidences of ozone effects on health indicators of natural populations of sacred from August 2001 to January 2003. We monitored 31 selectively chosen sampling plots with passive monitors. Two additional fir forests with expected low exposure to ozone were used as control. Mean hourly ozone concentration per period (2 to 3 weeks each), fluctuated between 4,826 x10-7 and 0,0441 ppm. Most ozone readings were high, the mean hourly concentration in Desierto de Los Leones was 0,0186 ppm, but only three readings marginally exceeded a 0,0400 ppm toxic threshold. Ozone concentrations in control areas had a lower average (0 ,0145 ppm), with erratic wide fluctuations. We found no relationship between ozone concentrations and sampling plot location, elevation, temperature or region. Foliage retention, crown density, vigor and stand basal area follow weak, but constant and consistent worsening trends as ozone mean site concentration increases. This trend suggests fir health reduction with increasing ozone concentration; control values are consistent with this trend. This result differs from reports of ozone damages on fir, except the case of Switzerland where fir occurs at high elevations and shows clear anatomic damages due to chronic ozone exposure, just like the Mexican case.

We evaluated the germination and survival in situ and ex situ of seedlings of Aspidosperma megalocarpon, Eugenia sp., Lonchocarpus castilloi, Manilkara zapota, Ormosia macrocalyx and Rollinia mucosa. We established nine blocks of 5 m x 20 m in the field, in which 360 seeds of each species were established in three successional conditions with three repetitions: mature tropical forest, advanced fallows and young fallows. The experiment was replied in a tree nursery using 40, 60 and 80% shade. We found no significant differences in the rates of germination and neither in growth due to variation in the natural cover. However, the rates of germination of A. megalocarpon and O. macrocalyx, and the rates of depredation of M. zapota and L. castilloi were affected by the coverage. Seeds sown in young fallows showed higher depredation, whereas seedling survival was higher here than in the other successional stages. In the tree nursery, no significant difference was found in the proportion of germinated seeds, the rates of germination and in growth. However, R. mucosa showed low survival (42%). The environmental conditions of the forests in Tabasco are under various stages of degradation and it is appropriate to start a rehabilitation program by introducing native species. This study indicates that this could be done by sowing the seeds directly in the forests without first producing seedlings in nurseries, which in turn would reduce the costs. It is recommend continuing research on the seed and seedling performance of other species that could be used to rehabilitate and restore the tropical forest.

This paper reports on mechanical properties and natural durability of avocado branch wood (Persea americana Mill.) with the objectives of providing a reliable property profile and to promote the rational use of this abundant yet largely neglected natural resource.  The mechanical properties (static bending, compression, shear, impact bending) and hardness were determined in accordance with European standards (CEN). Natural durability was assessed according to the European standard EN 350-1 (agar block test) using the white rot fungi Trametes versicolor and Phanerochaete chrysosporium, and the brown rot fungus Postia placenta. Avocado trees yield a low to medium density (0,44-0,54-0,64 g/cm3 at 12% mc) branch wood with below average strength under static bending, compression and tension parallel to the grain and average values for longitudinal shear, impact bending and hardness. The wood is rated non-resistant (class 5 according to EN 350-1) and thus is not suitable for exterior applications unless treated. Considering its property profile and the small dimensions available, avocado wood is recommended for general carpentry, furniture, interior paneling, glue-boards for closets and cabinets, and glue-lams for indoor framework.

This study was aimed to contribute to the knowledge of anatomy and ultra structure of the 3 species of wood of Prosopis growing in heterogeneous forest dry Chaqueño Park. The study material was collected in the province of Santiago del Estero northwest Argentina. The species studied were: Prosopis vinalillo, Prosopis alba and Prosopis nigra. The wood of the species was described macroscopically using a magnifying glass. For microscopic study were prepared permanent slides from the three planes of wood and dissociated material to measure the cellular elements. The results show that the 3 species are very similar and consistent with the structural features of the subfamily Mimosoideae. However, the number of vessels/mm2 was quite variable between species and between individuals of the same species. In the cases of intervessel, vessel-ray and vesselparenchyma pits is important to describe its shape, type, distribution and ornamentation. Samples observed under scanning electron microscope allowed displaying ornaments in pits and striations on the vessels walls. These striations were shown to be characteristics of the 3 Prosopis species studied.