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Search Results: 1 - 10 of 592138 matches for " María Rafaela;Návar-Cháidez "
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Análisis de sequías y productividad con cronologías de Pseudotsuga menziesii Rob. & Fern., y su asociación con El Ni?o en el nordeste de México
Arreola-Ortiz, María Rafaela;Návar-Cháidez, José de Jesús;
Investigaciones geográficas , 2010,
Abstract: this research was conducted to construct chronologies, to understand climatic shifts, and to determine productivity changes of psesudotsuga menziensii mirb. franco of the sierra madre oriental mountain range of nuevo león, méxico. radial growth patterns, drought episodes and productivity data were studied from the tree rings growth patterns during a 120 years study period. we also studied the association between recorded climate parameters and that hit chronologies using data of four climatic stations. chronologies were also associated to global scale climate events, the multivariate enso index (mei) and climate parameters associated to chronologies were reconstructed. it was noted that chronologies show four main drought episodes (1885-1903, 1907-1937, 1950-1963, and 1998-2003) that hit the highlands of northeastern mexico. productivity has a mean radial growth values of 0.82 mm y-1 and 1.18 mm y-1 during drought and wet episodes, respectively. there is a good association between chronologies and winter rainfall. reconstructed winter rainfall shows an increasing pattern in time and the mei is negatively associated to the chronologies indicating that the presence of wet and cold winters and early spring promote radial growth of trees in northern mexico.
Análisis de sequías y productividad con cronologías de Pseudotsuga menziesii Rob. & Fern., y su asociación con El Ni o en el nordeste de México
María Rafaela Arreola-Ortiz,José de Jesús Návar-Cháidez
Investigaciones geográficas , 2010,
Abstract: Con tres cronologías de Pseudotsuga menziesii Mirb. Franco obtenidas en la Sierra Madre Oriental (SMO), en el estado de Nuevo León, México, se determinaron periodos de sequías y productividad analizando el patrón de crecimiento radial durante un lapso de 120 a os. Se estudió la asociación entre el índice de crecimiento radial de las cronologías y los registros instrumentales de factores climáticos (precipitación y temperatura), obtenidos de cuatro estaciones meteorológicas vecinas a los sitios de muestreo. Se asociaron las cronologías con el índice multivariado del ENSO (MEI). Los resultados indican que en las cronologías resaltan cuatro periodos de sequías que se presentaron entre los a os: 1885-1903, 1907-1937, 1950-1963 y 1998-2003. La productividad disminuye notablemente de 1.18 mm a o-1 de crecimiento radial en épocas húmedas a 0.82 mm a o-1 durante la presencia de sequías. Existe buena asociación entre el índice de Crecimiento Radial Estandarizado (ICRE) de las cronologías con la precipitación invernal observada. La reconstrucción de la precipitación invernal basada en las cronologías, muestra un ascenso paulatino a través del tiempo, desde 1880 hasta 2003. La correlación del ICRE de las tres cronologías y el MEI presenta buena asociación en la mayoría de los meses del a o, principalmente, durante los meses que cubren las estaciones de oto o, invierno y primavera, indicando que el crecimiento del ancho de los anillos se ve favorecido con la presencia de bajas temperaturas y precipitaciones por arriba del promedio durante el invierno o la etapas primarias de la primavera.
Dendrocronología de Pseudotsuga menziesii (Mirb.) Franco de la Sierra Madre Oriental en Nuevo León, México
Arreola-Ortiz, María Rafaela;González-Elizondo, Martha;Návar-Cháidez, José de Jesús;
Madera y bosques , 2010,
Abstract: tree-ring chronologies for pseudotsuga menziesii were constructed for three sites of the sierra madre oriental mountain range of the state of nuevo leon, mexico: el potosí, la encantada and la marta. the correlation coefficients between chronologies, the normality tests on the ring width, and an index of ring width indicate both, the climate regionalization and the decadence on diameter growth of pseudotsuga menziesii (mirb.) franco populations. potential subtle climatic changes may be contributing to the decline of radial growth of the three plant communities studied.
Los bosques templados del estado de Nuevo León: el manejo sustentable para bienes y servicios ambientales
Návar-Cháidez, José de Jesús;
Madera y bosques , 2010,
Abstract: in this research paper, information is presented on the dasometric features of standing volume, diameter, top height, tree density, diameter distributions, tree and stand productivity, aboveground biomass, carbon in aboveground biomass and the tree biological diversity of temperate forests of the state of nuevo leon, mexico. this information was derived from 63 inventoried sites within the framework of the forest inventory of 2004-2006. it is concluded that temperate forests are in juvenile state with diameter distributions skewed to the right, with low tree density, low densities of standing volume, biomass and carbon stocks. tree productivity is also small since it does not surpass on the average 0,36 cm y-1. tree diversity at the site scale is also small since less than four species are found on the average on these sites. there was statistical evidence that productivity is related to tree diversity and structural diversity in a positive and linear manner. therefore, there is a great potential to sustainably manage these forests for a wide range of goods and services. it is recommended a light management for goods for 15 years and to carry on the appropriate silvicultural practices to enhance tree diversity as well as structural diversity to increase productivity.
Productividad foliar y radicular en ecosistemas forestales del Noreste de México
Návar-Cháidez, José de Jesús;Jurado-Ybarra, Enrique;
Ciencia forestal en México , 2009,
Abstract: primary productivity is a key to understand stocks and fluxes of several biogeochemical elements. the aim of this research project was to measure leaf and branch fall in 75 1 × 1m traps, suspended by ropes with at least three replicates in each of 16 plant communities of northeastern mexico. root production was measured during excavations using metal cylinders where roots were extracted. the results showed a great deal of variation on the measured parameters within and between plant communities. average branch and leaf fall (± confidence intervals α = 0.05) was 3.79 mg ha-1 a-1 (± 1.43), where highest productivity was recorded on sites reforested with cupressus spp (9.25 ± 2.58), tamaulipan thornscrub located in an intermittent wetlands (7.23 ± 2.09) and a pinus pseudostrobus reforestation site (5.27 ± 0.93) and the remaining of the plant communities recorded productivities of less than 4.05 mg ha-1 a-1. there was some evidence that the variation in productivity was associated to total standing biomass. branch and leaf fall followed a seasonal tendency with contrasting tendencies in subtropical and temperate plant communities. finally leaf and branch fall are an important productivity component to be considered in any mass or energy balance of ecosystems of northeastern mexico.
Diversidad, estructura y productividad de bosques templados de Durango, México
Návar-Cháidez, José de Jesús;González-Elizondo, Socorro;
Polibotánica , 2009,
Abstract: there is little quantitative evidence of the effect of diversity and structural complexity on stand productivity of temperate coniferous forests of northern mexico. our observations indicate that well-balanced canopy strata, unequal diameter structure and tree diversity enhance stand productivity. although further research is required to understand the long term effect of tree diversity and canopy structure on stand productivity, these preliminary observations emphasize the importance of promoting silvicultural practices to maintain stand structure and diversity in forest management plans and silvicultural prescriptions that aim to maintain ecosystem functions, diversity and productivity.
Estimación de factores de expansión de carbono en comunidades forestales templadas del norte de Durango, México
Silva-Arredondo, F. M.;Návar-Cháidez, J. de J.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2009,
Abstract: this research set as objective to quantify carbon stocks in aerial biomass of temperate communities of northern durango, mexico. the carbon concentration of several biomass components of 25 trees were quantified in the laboratory. dasometric data of inventoried trees, together with alometric equations to estimate biomass and carbon concentrations were employed to estimate carbon expansion factors using stand volume. the carbon expansion factors were modeled as a function of the dasometric features of trees at the stand scale and the normal probabilistic density function was fitted to obtain information on the skewness of this parameter. the results showed that the carbon expansion factors are dependent of the mean tree height and they distributed normally. this information is important for the development of environmental management plans of forest ecosystems and will allow the broader use of forest inventory data.
Comparación de técnicas de estimación de volumen fustal total para cinco especies de pino de Durango, México
Corral-Rivas, S.;Návar-Cháidez, J. de J.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2009,
Abstract: in this study, ten methods for estimating total stem (bole) volume inside bark, were compared for five pine species distributed in the state of durango, mexico. total stem volume was thus estimated by the conventional equations of 1) smalian, 2) newton and 3) revolution of solids, and the taper models of 4) amidon, 5) biging, 6) clutter, 7) kozak 1, 8) kozak 2, 9) newnham and 10) rustagi and loveless. total tree stem volume models of a) schumacher and hall, b) spurr, c) spurr transformed, d) honer, e) sloboda, f) naslund and g) australian, were fitted to estimated volumes by the indicated mathematical methods using the independent variables, diameter at breast height (d) and total height. volume data generated by those conventional models were compared using covariance analysis with the aim to employ those that are compatible with the tree volume estimation by the conventional equation of smalian. results showed that the taper equations of amidon and biging provided comparable tree and stand volumes to those estimated by the conventional approaches that employ the volume estimated by the huber, smalian or newton equations. therefore, these two taper equations are widely recommended to estimate total or merchantable volume of the five studied pine species of durango, mexico.
Valoración económica de los servicios ambientales hidrológicos en El Salto, Pueblo Nuevo, Durango
Silva-Flores, Ramón;Pérez-Verdín, Gustavo;Návar-Cháidez, José de Jesús;
Madera y bosques , 2010,
Abstract: this research explored willingness to pay (wtp) and willingness to accept (wta) payment for conserving water supplies in el salto, pueblo nuevo, durango. personal interviews were applied to both el salto water users to estimate wtp and land resource owners to estimate wta. production costs were estimated at the watershed "la rosilla" near el salto. the production costs included storage, protection, restoration and water supply to el salto residents. in addition, production of water was estimated using a mass balance approach. the results showed that the watershed produces on the average 2,10 mm3/year. about 90% of the water users surveyed in the study were willing to pay for the environmental hydrological service an average of $17,18 for month. likewise, resource owners were willing to accept about $320,00 for month ($5,26/ha/year) as a compensation to forgo forest harvest and stimulate water production. differences between wtp and wta coincide with many other studies that indicate wta is larger than wtp. average production cost was estimated at $2,49/m3 of water for the first year and $2,09/m3 for the remaining years over a 10-year planning period. the cumulative wtp, based on the number of households of el salto, would not be enough to pay for all production costs. other external programs such as carbon sequestration and government subsidies, etc., are necessary to reduce the gap between estimated wtp and production costs.
Detección de Salmonella spp. en melón Cantaloupe en unidades de producción y unidad de empaque
Morales-Hernández, Lucía;Hernández-Anguiano, Ana María;Cháidez-Quiroz, Cristóbal;Rendón-Sánchez, Gilberto;V. Suslow, Trevor;
Agricultura técnica en México , 2009,
Abstract: fresh cantaloupe melons (cucumis melo l.) group reticulatus coming from the state of guerrero, mexico, have been associated with outbreaks of salmonellosis in the united states of america and canada. these countries suspended the importations of cantaloupe melon from mexico due to the outbreaks in 2001. this study evaluated the food safety quality of cantaloupe melon, with the detection and identification of salmonella in two production units and a packing facility unit in zirándaro de los chávez, guerrero. 100 cantaloupe melons (50 of the production units and 50 of the packaging unit), collected in january and april 2005, were analyzed by conventional bacteriological methods and growth in selective media for detection of salmonella, as an indicator of fecal contamination. the proportion of melons with presence of salmonella was 4%, in one of the field production units and 20% in the packing unit. salmonella was detected in fruits irrigated with filtered but not chlorinated river water and handled by workers with poor hygiene. characterization by polymerase chain reaction (pcr) demonstrated that, two of six strains of presumptive salmonella gave positive amplifications with the pair of primers sal-3 and sal-4 as with inva-1and inva-2. for four other isolates only two were observed with inva-1 and inva-2. these results suggest that in the region of zirándaro de los chávez there are more than one serotype of salmonella, and demonstrate the importance of implementing prevention programs to ensure the sanitary quality of cantaloupe melon.
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