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

Wood of Quercus obtusata is described and the variation of nine quantitative wood characters is evaluated through tree height and diameter, elevation and 11 climatic parameters in four sites. Pearson correlation showed that only the narrow vessel element length is significantly correlated with tree height (rp = 0,70, p <0,02). The principal component analysis revealed that three components explain 76,46% of the total variation and ten variables are those with the highest loadings. Moreover, this analysis segregated the localities due to altitude and some climatic variables as for temperature and rainfall throughout the year, which have an effect on vessel elements length, as well as on fibres length and wall thickness. The driest locality, Arcos del Sitio, and in that of higher elevation, Santa Ana Jilotzingo, have the shortest vessel elements with wider diameter (561 µm and 552 µm respectively) than the most humid environment, Santa Catarina (621 µm). The fibres neither diminish in size with the elevation nor increase with tree height. The analyses suggest that the microclimatic parameters of each location need to be accounted when recommendations for Q. obtusata wood used as raw material or in reforestation programs are given.

The aim of this study is to analyze the kiln-drying of chalamite wood (Pinus pseudostrobus) using a 22 factorial design. Two drying schedule were applied: the first one was an intense schedule with temperatures from 76°C to 87°C, and the second one a soft schedule with temperatures from 60 °C to 82 °C; these schedules were applied with two air velocities: 2,05 ms-1 and 3,35 ms-1. Drying time and quality of wood were the responses evaluated. According to the results, the drying time is affected by the schedule intensity, and the wood quality depends on the drying schedule and air velocity. Statistically, it was observed that a drying schedule with temperatures from 76 °C to 87°C and air velocity of 3,35 ms-1 reduces the drying time and defects development in wood.

This work refers to the classical theory of tree stem form. It shows the derivation of a general sectional volume equation for frustums of solids of revolution generated by the function y2 = pnxn where, pn is a positive constant, and n any positive integer. The cylinder case presents a singular situation because of its sectional volume equation cannot be defined for n = 0 as it is known for the generating function. However, that geometry is implicit as a trivial solution of the derived equation. The known sectional volume equations for frustums of paraboloid, conoid and neiloid are particular cases of that equation for n =1, 2, and 3, respectively. The general sectional volume equation has an unexpected statistical nature. It is given as an arithmetic mean of geometric means The classical theory of tree stem form continue being present in the forest measurement teaching and research. This work could contribute to improve the understanding on that theory. 

The Sierra Zapaliname (SZA) is the most important source of water for Saltillo and neighboring settlements. Population increase is putting pressure on limited water sources, therefore it is necessary to have a better understanding of historical hydroclimate variability for planning the proper use of limited water resources. Tree-ring series were developed for the lower, mid, and upper sections along an altitudinal gradient in SZA. The chronology length was 412 years (1595-2006), 306 years (17002005) , and 603 years (1400-2002), for the lower, mid, and higher elevation, respectively. The lower elevation tree-ring chronology had higher climatic sensitivity to dry periods as compared to those of the mid and upper elevation sections. Intense and extended droughts were detected along the altitudinal gradient in the 1440s to 1450s, 1530s, 1590s, 1640s, 1660s, 1690s, 1710s, 1740s, 1750s, 1760s, 1790s, 1860s, 1890s, 1920s, 1950s, and 2000s, and produced local and regional food shortage and epidemic outbreaks. Severe droughts were detected at frequencies of 100 years followed by mid intensive droughts at 50-year periods. The climatic influence of ENSO in determining hydroclimatic behavior of SZA has not been significant and other circulatory patterns (cold fronts, hurricanes, tropical storms) could better explain the historical climate variability that has characterized this mountain range.

The Myrtaceae family in Mexico is represented by twelve genera widely distributed in temperate, tropical and semiarid regions. The family has economic importance due mainly to the extraction of wood (from Eucalyptus spp.), of fruit for human use (Psidium spp.) and to the practice of apiculture (in Eugenia spp.), among other uses. Several genera representing the family have been recorded in Quintana Roo, among which Eugenia, with several species, is well represented in the tropical rainforest. Wood of this genus has important local uses: poles and pillars used in the construction of rural houses, it has also been used to build railroad (sleepers). Valuable melifer species have also been found. Its wood structure has been poorly studied; therefore this paper describes the anatomy of Eugenia capuli (Schlecht. & Cham.) Berg. and of Eugenia mayana Standley, wich were collected in the common land (ejido) Cafetal Limones, Quintana Roo. The anatomical descriptions, have produced esthetic, macroscopic and microscopic studies using the three typical cuts and dissociated material. A statistical analysis was done using the measurable characters which were determined based on the value of the mean. Botanical data was included in each description. In both species, the wood is light brown, with diffuse-porous and the vessels have simple perforation plates; the axial parenchyma comes in stripes and it is diffused; rays are heterogeneous type I, II, III and libriform fibres. E. mayana is different from E. capuli in that it has axial parenchyma vasicentric, triseriate rays and its fibres have gums. 

The tropical dry forest is an ecosystem under strong human pressure. It is found both inland and on coastal dunes. The objective of this research is to identify native tree and palm species growing on dunes that are used by local communities. In this research we carried out surveys and interviews among residents of San Isidro and Colonia La Mancha, in the coast of Veracruz on the use of trees of the tropical dry forest on dunes. Among the 55 registered species, Cedrela odorata, Diphysa robinioides, Enterolobium cyclocarpum, Bursera simaruba, Gliricidia sepium, Tabebuia rosea, Chrysobalanus icaco, Guazuma ulmifolia, Acacia cochliacantha, Brosimum alicastrum, Bumelia celastrina, Cocos nucifera, Maclura tinctoria, Piscidia piscipula, Spondias mombin and Ficus spp. were mentioned by more people. Eighteen uses were recorded, being the most frequent construction of houses (119 mentions), posts for fences and live fences (99), firewood (72) and food (48). Four of the uses mentioned refer to environmental services provided by these plants in the dunes. The species with higher number of uses is Gliricidia sepium and Bursera simaruba is the species in which more parts are used, followed by Gliricidia sepium, Guazuma ulmifolia and Brosimum alicastrum. We also inquired about the parts of the tree being used, the frequency, their sale and local price. Based on the results we suggest a group of species that can be used to increase species tree richness in the secondary growths and grassland on dunes, which will provide wood, forage, etc., to the local inhabitants and help maintain the tree cover of the dunes.

Rhizophora mangle L. (red mangrove) and Avicennia germinans (L.) L. (black mangrove) seedling survival and growth were evaluated in reforestation trials as part of an environmental restoration and regional development program in the Chabihau coastal microbasin, Yucatan, Mexico. Building of road bridges over inlets modified swamp conditions by increasing tide reflux and reducing salinity extremes. Mangrove seedling survival is now regulated by flood level and growth by salinity. Red mangrove survival was highest in deeper areas and with higher development with lower soil salinity (3 ,28 psu ± 0,32 psu), while black mangrove survival was higher in shallower areas and development was highest with higher soil salinity (45,5 psu ± 0,50 psu). Building of sediment beds to control degree of flooding aided in increasing black mangrove survival, and clearing of springs to reduce salinity ensured proper growth. Survival was higher for nurseryraised red mangrove seedlings than for directly planted red mangrove seedlings. High black mangrove natural incorporation was probably favored by the lower water depth and higher salinity in the swamp during 2006, a low rainfall year. Reforestation programs need to include monitoring of surface and soil hydrological parameters (especially flood level and salinity) to aid in the selection of optimum species and methods for higher seedling survival and improved growth.

The effect of land use on the structural diversity of Tamaulipan thornscrub in northeastern Mexico was examined. The objective was to determine whether land use modified diversity, ecological indicators, structural and vertical distribution of trees and shrubs. The analysis was performed by comparing three ecosystems with different land use history: extensive cattle grazing, traditional agriculture and clear cutting with 21 year of abandonment. The methodology used was a combination of rectangular sites and a sampling analysis called "structural group of four trees". Results showed differences in diversity, ecological indicators, vertical distribution and dimensional structure.

The interpretation of the nomograms from the vector analysis technique for nutrient status diagnosis of preformed growth forest tree species frequently is a difficult task that may lead in some cases to vague or even unsatisfactory conclusions. The present document contains a guide to help nutrient diagnosticians to interpret such nomograms. As compared with the existing tabular models for nomogram interpretation, this guide includes a higher amount of possible vectors, it provides a wider spectrum of interpretation possibilities for each of the vectors, and discriminates the interpretation of the nomograms according to the level of manipulation of the nutrient being analyzed. Furthermore, if it applies, the status of the nutrient before and after the application of treatments is defined.

Not applicable.