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

La resiliencia ecológica está integrada por dos componentes: resistencia y recuperación. En áreas de bosque tropical seco (BTS) donde se elimina la vegetación para establecer actividades agrícolas, la resistencia de la vegetación a este disturbio antrópico es irrelevante. Sin embargo, una vez que se abandonan los campos agrícolas, los sitios inician un proceso de recuperación de sus atributos ecológicos. El objetivo de este trabajo es proponer un marco metodológico para la evaluación de la resiliencia ecológica de los BTS mediante la combinación secuencial de la percepción remota y muestreos en campo, considerando el marco conceptual de la resiliencia y la ecología del BTS. Se plantea que la evaluación de la resiliencia ecológica del BTS tenga las siguientes aproximaciones: (1) la primera incluye un análisis de la recuperación de los atributos del BTS (e. g., cobertura, altura) a nivel regional y de paisaje, mediante insumos de percepción remota (e. g., imágenes de satelite) que muestren el cambio de cobertura y uso del suelo; (2) después, el análisis requiere abordar la recuperación desde una perspectiva a nivel local que implica el análisis de las variables ecológicas más relevantes como la estructura, la diversidad y la función ecológica; (3) finalmente, a partir de los insumos a nivel local, es posible retornar a niveles de trabajo menos detallados (e. g., regional y paisaje) y modelar los datos obtenidos en campo mediante índices de vegetación. Este planteamiento permite evaluar la resiliencia ecológica de un ecosistema y las causas que la promueven a diferentes escalas espaciales.

Croton guatemalensis is a threatened and multipurpose species in communities of southeastern Mexico and Central America. For the first time, its reproductive phenology and its relationship with environmental variables present in four different natural protected areas of the Zoque Tropical Forest Biological Corridor was determined. Throughout a year the flowering and fructification of the species was monitored, the local environmental variables were recorded and fruits and seeds were collected to determine, under a random design, the germination of the seeds and the growth of seedlings in the laboratory and in nursery respectively. In all cases, flowering was presented from July to April, while fructification occurred from March to September, coinciding with the months where the rains diminish considerably. In terms of seed germination, it presented a statistically significant difference between seeds from the four protected areas. The most contrasting results were presented between La Pera and Area Villa de Allende (98% ± 3.84% and 6% ± 3.84% respectively). According to the generalized linear model, soil porosity was the only variable that influenced the germination of the species (the higher the porosity, the higher the percentage of final germination, t = 2.237, P = 0.0503). Because this is the first study on the ecophysiology of C. guatemalensis in southern Mexico, the importance of it becomes relevant when providing fundamental reproductive information for the generation of strategies for conservation, restoration and forest management of the species.

Trees sequester and store large amounts of carbon within their biomass, thus helping to mitigate the effects of the greenhouse gasses (GHG). To date, no allometric equations exist to estimate biomass of the forest tree species from Guerrero, Mexico. That is why the aim of the present study was to generate equations to estimate aboveground biomass for Pinus oocarpa Schiede and Quercus resinosa Liebmann. Databases consisted of 33 and 19 sample trees for the pine and oak species, respectively, all of them distributed in temperate forest within Hueyapa river micro-watershed, Guerrero, Mexico. The biomass was estimated based on the dry weight of 6 to 14 samples per tree component, according to tree size. Power models were adjusted in their linear form and with Box-Cox transformation. The model that best estimated the aboveground biomass in P. oocarpa was the power function and for Q. resinosa it was the one obtained with the Box-Cox transformation, using the logarithm of the diameter at breast height ( ) and the transformed combined variable  as the independent one, respectively. The allometric equations generated fill the existing vacuum for the estimating the aboveground biomass of these forest species in Guerrero state.

The charcoal produced in Mexico comes from different species and processes, so that its characteristics have a wide variation. The objective was to characterize the charcoal produced in the North Central region of México according to international standards of quality and energy. Three bags of nine commercial provenances of mesquite charcoal (Prosopis sp.), ebony (Ebenopsis sp.) and oak (Quercus sp.), were randomly collected. Readings were obtained for particle size, volatile material, moisture content, fixed carbon, calorific value and the elements Mg, Ca, Cu, Zn and Fe. Data were subjected to analysis of variance under a completely randomized design with four replications per bag and comparison of means were developed with Tukey test. It was found a predominance of 20 mm > X ≤ 50 mm size, only two provenances showed fragments > 100 mm. Mean values were: moisture content 5.1%, volatile material 25.9%, ash 6.3% and fixed carbon 62.7%. The highest calorific value was 27 669 kJ kg-1 and higher values for Ca (177 267 mg kg-1) and Mg (20 263 mg kg-1). Provenances 5, 7 and 8 showed more fixed carbon and volatile material. The variation was related to plant species, provenance as well as the method of production. It is necessary to improve charcoal quality according to particle size, fixed carbon and calorific value; as well as low levels for moisture content, volatile material, and ash content. The constant evaluation of these characteristics will improve the quality of the coal produced in México and facilitate its trading in the international markets.

Climate exerts a dominant control over the natural distribution of species. Bioclimatic models are an important tool for assessing the potential responses of species to climate change. The objective of this study was to estimate the distribution of Dendroctonus mexicanus Hopkins, under current and future climate scenarios (year 2050) in two Representative Concentration Pathway (RCP´s) 4.5 and 8.5. Characteristics of model (creation, calibration, selection and evaluation) were carried out in kuenm, an R package that uses Maxent as the modeling algorithm. Model suitability of D. mexicanus was composed mainly by mean temperature of warmest quarter (76.6%), temperature annual range (12.5%) and precipitation of driest quarter (5.5%). In Mexico, the high suitability of D. mexicanus is 121 310.7 km2; only five states: State of Mexico (17 879.7), Michoacan (15 669.8), Puebla (14 693.1), Oaxaca (14 380.1) and Hidalgo (13 830 km2), comprise more than 63% of the estimated high suitability. For 2050 it is estimated a decrease of 51 thousand km2 of climatic suitability specially in Michoacan, Jalisco and Guanajuato, but an increase of about 25 thousand km2 toward northwest Mexico. A shift and a probable migration of this bark beetle toward higher latitudes (30 ± 15 km) and altitudes (~ 100 m) extending its distribution up to 3700 masl is feasible. These relevant changes in their probably distribution may involve potential forest damage.

In forestry there is a long history in the parameterization and use of models to quantify and predict the growth and yield of forest stands, as a fundamental requirement to optimize the application of silvicultural practices for sustainable forest management. The status of Mexico on the use and parameterization of forest models shows significant advances in recent years, which has resulted in the constant generation of biometric tools for the implementation of planning systems and forest management plans. Nevertheless, there is still an urgent need to generate biometric tools to optimize the processes of planning and utilization of forest resources. Currently, in Mexico there is an important collection of models for various purposes, such as volume models, taper models, compatible taper-volume systems, height-diameter models, site index models, biomass, carbon and nutrient content of ecosystems, density management; whole-stand, diameter distributions and individual tree growth models. Given the dynamic environment that involves using biologically more realistic variables to model physiological processes related to forest growth, much remains to be done in forest modeling in Mexico. However, important steps have been taken in the establishment of permanent sampling plots for the periodic measurement of forest growth, and the characterization of structural changes of forest stands. These, coupled with capacity building in biometrics and modeling throughout the country, make it possible to prognosticate important advances in this area in the near future.

The wood fibre used by the paper industry originates primarily from forests. Apart from Gmelina arborea, there are other fast-growing plant species whose fibre characteristics are yet unknown. In order to relieve the pressure and demand on G. arborea, this work was aimed at characterizing and comparing the fibres of four tree species (Parkia biglobosa, Arzadirachta indica, Alstonia boonei and Cassia siamea) to G. arborea, with the intention of elucidating their suitability for the pulp and paper industry. The trunk wood samples used in this study were collected from the Botanical Garden of the University of Nigeria, Nsukka, while the study was conducted in the Plant Anatomy Laboratory in the Department of Plant Science and Biotechnology, University of Nigeria, Nsukka, Enugu State-Nigeria. The results showed that the mean fibre length ranged from 1.00 mm in P. biglobosa to 1.70 mm in A. boonei. The fibre lengths of G. arborea and A. booneidid do not vary significantly (P < 0.05). The Runkel ratio ranged from 0.624 to 3.227 across the species with G. arborea and A. boonei recording the lowest values. Conclusively, A. boonei is another pulp wood with good paper-making potential that could substitute the already known G. arborea.

The following work presents the results obtained by fire management applied in coniferous ecosystems, in the Agroforestry enterprise La Palma, Pinar del Río, Cuba with the purpose of looking for economic and versatile alternatives for forest resources management. Although in Cuba, prescribed burns have few antecedents, this practice is implemented in several countries as a support tool for its integral forestry management plans. Little attention is paid in Cuba to prescribed burns due to the scarce information available about its effects at medium and long terms in forest ecosystems. In this paper, some aspects of prescribed-burns influence such as: definition, application time, fire effects on fuel material, vegetation and superficial glide are analyzed. Results show that prescribed burns can represent a support alternative in integral forestry management because of the reduction of fuel materials and the risk of forest fires; also, they allow to mitigate forest fires effects on surface draining and contribute to pine ecosystems conservation.

The hydroclimatic reconstruction is relevant to understand how a forest watershed works and take decisions about its management. In this study the precipitation and streamflow on Piaxtla river watershed was reconstructed, using tree-ring width index values from Pseudostuga menziesii. From seven dendrochronological series, a regional series (RS) was built. The correlation of RS with ocean-atmosphere phenomena like El Nino/Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, and Palmer Drought Severity Index was tested. Results showed the reliability of reconstructing the November-April precipitation and the November-August streamflow from the early wood series with verified and validated equations: Precipitation = -271.538 + 447.764*(Early wood index), (r = 0.85, n = 49, p < 0.0001) and Streamflow = 5.123 + 0.623*(log10(Early wood index)), (r = 0.68, n = 46, p < 0.001). Except for the Atlantic Multidecadal Oscillation, all climate circulatory events had significant correlation to the dendrochronological information. This study confirms the high sensibility of P. menziesii in the Sierra Madre Occidental reflected in a high correlation among tree-ring width series and hydroclimatic variables. For this reason, the potential of this study should be expanded to monitor any change in the availability of water resources and for the valuation of hydrological environmental services.

The dynamic between litter fall and its decay is part of the functioning of ecosystems. The production, loss and rate of decomposition of forest litter and secondary vegetation in ecogeographic units (EU) of mountain slopes, terraces and fluvial plains in the subregion of the rivers of Tabasco in Mexico were evaluated. In each EU, six conglomerates were established with four plots of 10 m x 40 m and in three plots of each conglomerate, 6 traps of 1 m2 were distributed (n = 144), which were collected from March 2014 to March 2015. To determine the remaining weight and the decomposition rate, the decomposition bags method was used, initially with 10 g of litter per bag (n = 384). The period to determine the decomposition was comprised from June 2014 to March 2015 and monthly, four bags were collected per conglomerate, which were dried at constant weight. The results show that the litter production of the secondary vegetation in the EU is similar to that of primary vegetation in two zones, while in only one of them it was higher. The weight loss and decomposition rate showed that, for primary vegetation, both are slightly higher than for the acahuales. These results may be significant due to the inexistent works about the production and decay of litter in the ecogeographic unit, that may help to secure the management and conservation of secondary vegetation in Tabasco state.