REFORESTATION ASSESSMENT IN THE FORMATION OF SOIL FROM TEPETATES
EVALUACIÓN DE LAS REFORESTACIONES EN LA FORMACIÓN DE SUELO A PARTIR DE TEPETATES
/ pages 303-312
In 1973 the Commission of the Lake Texcoco Plan initiated a soil and water conservation program, through the reforestation of the hilly zone and restoration of the grassland in the low areas in the lands of the former lake bed. It has been 37 years, and there are few studies that assess the direct impact of reforestation on soil formation and the recovery of its functions as part of the ecosystem. The present study was conducted in the eastern part of the State of Mexico, in order to evaluate the impact of different forest plantations (cedar, eucalyptus, pines and casuarinas) on soil formation in a red tepetate area. Three soil profiles were described for each planting, and physical, chemical and micromorphological analyses were carried out. Results show that casuarinas and cedars are the spe¬cies that contribute the most to soil formation and increase the water retention capacity in the area. Although pines and eucalyptus adapt favorably to these environmental conditions, their influence in environmental restoration is considerably lower.
ANALYSIS OF LAND USE CHANGES IN THE WATERSHED OF METZTITLÁN RIVER (MEXICO) USING SATELLITE IMAGERY: 1985-2007
ANÁLISIS DE LOS CAMBIOS EN EL USO DEL SUELO EN LA CUENCA DEL RÍO METZTITLÁN (MÉXICO) USANDO IMÁGENES DE SATÉLITE: 1985-2007
/ pages 313-324
This work evaluated both loss of vegetal cover and urban growth over the last 22 years in the water¬shed of Metztitlan River, Hidalgo, Mexico, with the purpose of monitoring land use change and plan¬ning better the future land use of the study area. Both Landsat images of 1985 (Thematic Mapper, TM) and 2007 (Enhanced Thematic Mapper, ETM+) were used to made thematic maps using the maximum likelihood algorithm. These maps were validated and spatially compared using a change matrix. Two processes of change were detected: (1) annual deforestation (0.5 %), where the most active changes were from scrubland and forest to seasonal agriculture; and (2) urban growth (4.3 % annual rate) displacing agriculture, forests, and grasslands.
ECTOMYCORRHIZAE ASSOCIATED WITH Pinus jeffreyi IN “CONSTITUCIÓN DE 1857” NATIONAL PARK IN BAJA CALIFORNIA, MEXICO
ECTOMICORRIZAS ASOCIADAS A Pinus jeffreyi EN EL PARQUE NACIONAL “CONSTITUCIÓN DE 1857” EN BAJA CALIFORNIA, MÉXICO
/ pages 325-332
The diversity of fungal species in three forest areas of Constitución de 1857 (he¬reafter referred to by its English name, Constitution 1857) National Park in Baja California, Mexico was studied. Samples were collected in August 2007 and Fe¬bruary, May and August 2008, obtaining 25 specimens belonging to three genera: four species of Geastrum, and one each of Suillus and Laccaria. The abundance of species was related to rainfall and ecological conditions of the site itself. Samplings were undertaken to collect secondary roots of mature trees of Pinus jeffreyi Grev. & Balf and ectomycorrhizal morphotypes were identified using DEMMY keys. We found six different morphotypes, suggesting that P. jeffreyi has an ectomycorrhizal association with at least six different species of fungi present in this area.
ECONOMIC VALUATION FOR THE REHABILITATION OF THE AXTLA RIVER, S.L.P.
VALORACIÓN ECONÓMICA POR LA REHABILITACIÓN DEL RÍO AXTLA, S.L.P.
/ pages 333-342
This paper presents the results of a study to determine the willingness to pay (WTP) for the protec¬tion, maintenance and improvement of the Axtla River by the inhabitants of Axtla de Terrazas, San Luis Potosi. For this study, the referendum format contingent valuation method (RCVM) was used. The results were analyzed using logistic regression techniques via maximum likelihood. We conclude that the variables family income, education and pollution damage positively influence WTP, while the bid offered, water quality, number of children who are economically dependent on the household head and age of the household head negatively affect WTP. The study found that residents are broadly receptive to contributing to the rehabilitation of the river, being willing to pay on average 57 pesos per month per household head.
CONSISTENCY BETWEEN GLOBAL AND REGIONAL LAND COVER MAPS IN THE STATE OF MICHOACAN, MEXICO
CONSISTENCIA ENTRE LOS MAPAS GLOBALES Y LOS MAPAS REGIONALES DE LA CUBIERTA TERRESTRE EN EL ESTADO DE MICHOACAN, MÉXICO
/ pages 343-360
For some years attempts have been made for constructing global maps using different types of images, methods and systems of nomenclature. These maps are difficult to validate and local-level accuracy can be very variable. The aim of the present study was to contribute to the validation of global land cover maps, comparing five of them for the particular case of the state of Michoacan, Mexico. The regional land cover map produced by the National Commission for Knowledge and Use of Biodiversity of Mexico was taken as reference, and consistency and spatial area as criteria. The comparison considering the original legends revealed inconsistencies, due in part to differences in classification systems. After a merged legend with six general classes was established, the overall ac¬curacy between maps ranged from 9 to 62 %. Only 2 % of the pixels matched in 4 maps (mainly towns and water) and 88 % agreed in 2 or 3 maps. The main problem is the discrimination between cropland areas and other kinds of vegetation. The more recent maps based on the nomenclature proposed by FAO had an increased accuracy, but not enough to consider them as appropriately detecting the main land covers. The use of global land cover maps in situations of great biodiversity must be adequately contextualized.
EFFECT OF FOREST HARVESTING ON MORPHOLOGICAL VARIATION OF Juglans pyriformis LIEBM.
EFECTO DEL APROVECHAMIENTO FORESTAL SOBRE LA VARIACIÓN MORFOLÓGICA DE Juglans pyriformis LIEBM.
/ pages 379-388
The forest harvesting based on the extraction of individuals phenotypically better, as well as other
factors, could degrade the forest by leaving trees of lesser quality and reducing genetic diversity. The
population of Juglans pyriformis in San José Buenavista, Veracruz (SJB) has been reduced by farming
and logging for timber production purposes under the Silvicultural Individual Selection Method.
The population of Coacoatzintla, Veracruz (COA) has been reduced by change of land use and illegal
logging. The objective was to determine the levels of phenotypic variation of J. pyriformis in SJB population
and contrast to COA populations found in a previously study, using the same method. In SJB
principal component analysis identified three main indicators, SHAFT, CUP and HIGH-DIAM with a
high coefficient of variation (26%, 30% and 42% respectively).
COMPARISON OF SPATIAL METHODS TO DETECT URBAN LAND-USE CHANGE
COMPARACIÓN DE MÉTODOS ESPACIALES PARA DETECTAR CAMBIOS EN EL USO DEL SUELO URBANO
/ pages 389-406,
This research describes and analyzes some methods of detecting land-use changes caused by ur¬ban growth in order to show their advantages and disadvantages. It also outlines those methods that provide favorable results based on geographical information and enable proper decision-making in urban land-use planning.
TECHNOLOGICAL PROPERTIES OF ALGARROBO WOOD (Hymenaea oblongifolia Huber.), FROM BAGADO-CHOCO, COLOMBIA
PROPIEDADES TECNOLÓGICAS DE LA MADERA DE ALGARROBO (Hymenaea oblongifolia Huber.), DE BAGADÓ-CHOCÓ, COLOMBIA
/ pages 411-422
The aim of the present study was to determine the technological properties of Algarrobo wood (Hy¬menaea oblongifolia Huber), from the municipality of Bagado-Choco. Samples collected from trees (wood cylinders) were studied in order to determine the microscopic characteristics, basis density and normal density. Moreover, the mechanical properties were estimated using the values of basic density. Results showed that Algarrobo wood shows scanty vessel (medium to large), fibers that have medium size and rays containing crystal that are thin to moderately long. This wood has a bad quality for production of pulp for paper. The basic density of wood was classified as light softwood with a mechanical resistance that oscillates from high to very high. Algarrobo wood can be used in manufacture of furniture, floors and decorative handles, among other uses.
POTENTIAL OF ORGANOGENESIS AS A STRATEGY FOR in vitro PROPAGATION OF Fitzroya cupressoides IN AUSTRAL SOUTH AMERICA
POTENCIAL DE LA ORGANOGÉNESIS COMO ESTRATEGIA PARA LA MASIFICACIÓN in vitro DE Fitzroya cupressoides EN SUDAMÉRICA AUSTRAL
/ pages 423-433
Fitzroya cupressoides, commonly known as Alerce in South American Spanish, is a conifer species native to southern South America, where its wood is highly prized for its beauty and durability. This study evaluated the effect of hormonal components supplemented with culture media on the organogenic process of Fitzroya cupressoides and analyzed the in vitro regeneration process by histological studies. The Quorin-Lepoivre (QL) basic culture medium, supplemented with different concentrations of indole 3-butyric acid (IBA), 6-benzylaminopurine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D), was tested using nodal segments and acicular leaves. A completely randomized design with five balanced replications was used; the experimental unit was a glass jar containing an explant, while a petri dish containing four foliar explants was used for inducing callogenesis. The treatment factor had significant (P = 0.001) effects on the response variables number of shoots and caulinary elongation. Duncan’s multiple range test confirmed that the treatments that had significant differences were 0.1 mg.L-1 of IBA and 1.5 mg.L-1 of BA for number of shoots per explant and 0.1 mg.L-1 IBA and 1.0 mg.L-1 of BA for caulinary elongation. Histological studies demonstrated the proliferation of meristematic structures from sub-epidermal tissue.