Víctor L Barradas | Universidad Nacional Autónoma de México (original) (raw)

Papers by Víctor L Barradas

Botanical sciences, Dec 15, 1999

Resumen. Una área a l ser deforestada para su explotación agrícola y/o ganadera experimenta camb ... more Resumen. Una área a l ser deforestada para su explotación agrícola y/o ganadera experimenta camb ios relevantes tanto en e l microclima como en el suelo. Estos cambios en co njunto pueden formar una barrera física que limita drásticamente e l establecimi ento de especies arbóreas con fines de reforestación. Desde e l punto de vista microclimático, e l estudio del balance de energía juega un papel muy importante cuando un ambiente es severamente transformado. Esto es debido a que toda la energía disponible tanto en un sitio no perturbado como uno perturbado se divide principalmente en los flL0os de calor late nte y de calor sensible. El compo rtamiento de estos flujos permite ll evar a cabo series de análisis con el objetivo de controlar las altas tasas evaporativas y e l ambiente térmico que presentan los sistemas degradados. Se realiza una revisión sobre el balance de e nergía y los flt0os de calor sensible y latente y demás componentes, así como de las diferentes técnicas de la manipulación de estos flujos. Palabras clave: aco lchados, albedo, balance de energía, evapotranspiració n, microclima. Abstract. The deforestation of a si te for agricu lture a nd / or cattle raising purposes changes either microclimate and soil properties. These environmental c hanges ca n act as physical barriers which drastically limits tree species establishment in reforestation. From microclimatic point of view, the study of the energy balance plays a key role when the original enviro nm e nt is severely changed. The net energy in a site is mainly dissipated by latent and sensible heat fluxes which are associated to evapotranspiration and thermal regimes, respectively. The analyses of these fluxes allow to design control systems to reduce the high evaporation rates and high temperatures registered in a deforested sile. Energy balance, latent and sensible heat fluxes and other components are analysed, and sorne techniques to manipulate energy balance are also presented.

TIP, Dec 1, 2015

Con el fin de determinar si el agua recolectada artificialmente de la niebla en la zona central m... more Con el fin de determinar si el agua recolectada artificialmente de la niebla en la zona central montañosa del Estado de Veracruz es apta para el consumo humano, se realizó un muestreo preliminar de enero a marzo del año 2010, periodo de mayor frecuencia de nieblas, para analizar sus aspectos físicos, químicos y biológicos y evaluar su calidad. Se encontró que el agua contiene metales pesados como el mercurio, organismos coliformes y cantidades altas de nitrógeno amoniacal, pero esto se puede solucionar aplicando un tratamiento de saneamiento para uso humano con un costo de 0.00341 USD L-1 que no incluye mano de obra ni infraestructura. Se discuten las causas que pueden originar su contaminación y se concluye que el agua recolectada de la niebla no es adecuada para el consumo humano, pero sí para la agricultura.

Agrociencia, Aug 15, 2018

managers, or others, with actions like crop substitution and new varieties, and to reprogram agri... more managers, or others, with actions like crop substitution and new varieties, and to reprogram agricultural tasks.

Ecosistemas y Recursos Agropecuarios, Dec 1, 2020

RESUMEN. Hemileia vastatrix, hongo causante de la enfermedad más devastadora de Coffea arabica L.... more RESUMEN. Hemileia vastatrix, hongo causante de la enfermedad más devastadora de Coffea arabica L. (roya del café), podría incrementar su distribución altitudinal debido al cambio climático, causando efectos adversos. Por ello, el objetivo fue se realizar una prospección del efecto del cambio climático en la incidencia de H. vastatrix. La investigación se realizó tomando datos de la zona cafetalera de Coatepec, Veracruz, México. Se analizaron las tendencias de temperatura máxima, mínima e índices de extremos climáticos de 1961 al 2010, propuestos por el Equipo de Expertos en Detección e Índices de Cambio Climático (ETCCDI). Las tendencias se relacionaron con las condiciones para la proliferación de H. vastatrix. La zona ha experimentado un aumento de temperatura máxima (0.2 • C década −1) y mínima (0.3 • C década −1); la precipitación y su intensidad diaria se han incrementado, aumentando la susceptibilidad a la incidencia y severidad de la roya del café y de otras enfermedades fúngicas. Palabras clave: Coffea arabica, enfermedades, índices climáticos, roya del café, tendencias climáticas. ABSTRACT. Hemileia vastatrix, the fungus that causes the most devastating disease of Coffea arabica L. (coffee rust), could increase its altitude distribution due to climate change, causing adverse effects. Therefore, realized a prospecting of the effect of climate change on the incidence of H. vastatrix. This study was conducted out taking data from the coffee growing area of Coatepec, Veracruz, Mexico. The trends of maximum, minimum temperature and climatic extremes indexes (1961-2010) proposed by the Team of Experts on Climate Change Detection and Indices (ETCCDI) were analyzed. Trends were related to conditions suitable for the proliferation of Hemileia vastatrix. The area has experienced an increase in the maximum temperature (0.2 • C decade −1) and minimum (0.3 • C decade −1). Annual rainfall and daily intensity have increased, increasing the susceptibility to incidence and severity from coffee rust and other fungal diseases.

La ciencia y el hombre, 1997

Botanical sciences, Jun 15, 1998

Resumen. La estacionalidad de la precipitación y el substrato en el Pedregal de San Angel deben j... more Resumen. La estacionalidad de la precipitación y el substrato en el Pedregal de San Angel deben jugar un papel importante en el estado hídrico de las plantas que en él habitan. Por lo tanto, se realizaron mediciones de conductividad estomática (g), potencial hídrico foliar ('P 1), densidad de flujo fotónico fotosintético (Q), temperatura del aire (Ta) y la diferencia de presión de vapor entre la hoja y el aire (DPV) en Buddleia cordata H.B.K., por ser una especie perennifolia y dominante del estrato arbóreo. Las mediciones se llevaron a cabo durante las estaciones seca y húmeda en el Pedregal de San Angel que es una comunidad que se desarrolla en un substrato de lava. Las conductividades que se registraron fueron de hasta 330 mmol m 2 s• 1 durante la época húmeda, mientras que en la época seca se redujeron hasta cerca de un 54%. Se realizaron dos tipos de análisis, el de la curva envolvente y el de regresión múltiple. Ambos análisis mostraron un efecto significativo de Q, Ta y DPV sobre g tanto en cada una de las épocas como anualmente y los estomas fueron más sensibles a estas variables en la época húmeda que en la seca. El efecto de 'P 1 , no fue significativo en los análisis por época, pero sí en un análisis anual. Los resultados de este tipo de análisis pueden ser una herramienta muy efectiva en la formulación de modelos matemáticos que simulen o pronostiquen la conductividad estomática. Palabras clave: Buddleia cordata, conductividad estomática, modelos matemáticos, Pedregal de San Angel, potencial hídrico. Abstract. Precipitation seasonality and substratum in Pedregal de San Angel can play a key role on plant water status. Therefore, stomatal conductance (g), water potential ('P 1), photosynthetically photon flux density (Q), air temperature (Ta) and leaf-air vapour pressure difference (VPD), were measured on leaves of Buddleia cordata H.B.K., because its perennial character and its dominance in the Pedregal. These measurements were carried out during the wet and dry seasons in the Pedregal which is a plant community developing in a lava substratum. The highest values of stomatal conductance were registered in the wet season (330 mmol m• 2 s• 1), however during the dry season, stomatal conductance was reduced by 54%. Upper limit enveloping curve technique and multiple regression analysis were performed to the data in order to study how g responded to the microenvironment and 'P,,. Results clearly showed that there was a significant effect of Q, Ta and VPD on g and stomata were more sensitive on humid season than during dry season. 'P 1 , effect was not significant during the humid season, nor the dry season, but annually. Results from these kind of analysis may be very useful during the formulation of mathematics models to simulate or predict stomatal conductance.

Journal of Applied Ecology, Apr 1, 1987

... LUIS FANJUL AND VICTOR L. BARRADAS ... The site has been previously described in some detail ... more ... LUIS FANJUL AND VICTOR L. BARRADAS ... The site has been previously described in some detail by Fanjul &amp;amp; Barradas (1985). A detailed climatic analysis of the area has been presented elsewhere (De Ita-Martinez 1983). ...

Ciencia - Academia de la Investigación Científica, 1996

ABSTRACT La modelación en Ia ecofisiologia vegetal se ha desarrollado recientemente debido a Ia c... more ABSTRACT La modelación en Ia ecofisiologia vegetal se ha desarrollado recientemente debido a Ia complejidad de los procesos biológicos de las plantas. La meta principal de los modelos generados en esta disciplina de Ia ciencia, es Ia de complementar el entendimiento de las funciones de las plantas, aunque tambien se pueden usar en contextos socio-económicos. En este trabajo se presentan los tipos de modelos que se usan en Ia ecofisiologia vegetal y se discuten sus implicaciones, ventajas y desventajas. Los modelos empíricos se usan con mayor frecuencia cuando se incrementa Ia complejidad de los procesos biológicos, mientras que los mecánicos se usan más en los procesos vegetales físicos (eg evapotranspiración) debido a que Ia complejidad del sistema es menor. Se discute el papel de estos modelos tanto en el método científico, como en una aproximación socioeconómica y se enfatiza su importancia en Ia sociedad. Finalmente, se concluye que las técnicas de modelación deben ser refinadas y que se debe dar mayor atención a los modelos mecánicos para poder entender con mayor precision los procesos ecofisiológicos de las plantas.

Scientia Agropecuaria, Feb 28, 2022

Negative impacts of climate change are expected in the production of Coffea arabica L. one of the... more Negative impacts of climate change are expected in the production of Coffea arabica L. one of the most commercialized tropical agroproducts in the world. However, most studies work with global circulation models, being of little use in making decisions on the scale of farm management. Given this, the objective of this study was to identify the suitability for the cultivation of C. arabica in the face of climate change and how tree cover mitigates the impacts of climate change in an agroforestry plot. The indices of climatic extremes were calculated (1961 to 2016 for Coatepec; 1985 to 2016 for Briones) and a trend analysis was carried out (Mann-Kendall). The temperature inside a plot, and on an open site, was monitored for two years (2017-2019). This was related to the climatic requirements of C. Arabica. Trends of increase (p < 0.05) of the minimum and minimum extreme annual temperatures were identified in the two stations near the plot (0.24 and 0.69 °C•decade-1 in Coatepec and 0.46 and 0.79 °C•decade-1 in Briones). The maximum temperature did not present significant increases, reducing the thermal amplitude. Both annual and seasonal precipitation shows trends of increase in intensity. All these conditions are still suitable for the cultivation of C. arabica. At the plot scale, the importance of tree cover is demonstrated, which in this agroforestry system allows to reduce the maximum temperature by 1.9 °C compared to an open site. Tree cover has also made it possible to mitigate extreme events.

International Journal of Biometeorology, Jul 27, 2021

Phenology has been useful to better understand the climate-vegetation relationship, and it is con... more Phenology has been useful to better understand the climate-vegetation relationship, and it is considered an indicator of climate change impact. Phenological data have been generated through multiple remote sensing techniques and ground-based observations through professional or citizen science. The combination of both techniques is known as cross-scale phenological monitoring. However, no comparative analysis has been carried out to assess the advantages and disadvantages of each of these techniques to characterize the phenological cycle of forest ecosystem species. This work is a content-analysis-based review of scientific literature published between 2000 and 2018 related to cross-scale monitoring methods, to estimate the phenological variation in different forest ecosystems worldwide. For this study, 97 publications related to cross-scale phenological monitoring were selected. We found that 71% of the articles aimed to corroborate the data generated through satellite imagery using surface data from either phenocams, flux towers, or from citizen science networks. More publications were published by authors in the USA (30%), Canada (8%), and China (7%). The most commonly used vegetation index was the normalized difference vegetation index (65%). Some deficiencies in the evaluation of the phenological phases of autumn when compared with surface observations were found. Flux towers and phenocams were included as alternatives for ground-based monitoring. Cross-scale phenological monitoring has the potential to characterize the phenological response of vegetation accurately due to data combinations at two different observation scales. This work contributes to specifying the methodologies used in gathering phenological parameters of the world’s forest ecosystems.

Plant and Soil, Aug 24, 2006

We examine the effect of mulches on the soil volumetric water content (SVWC), pH, carbon (C), tot... more We examine the effect of mulches on the soil volumetric water content (SVWC), pH, carbon (C), total and mineral (NH 4 and NO 3) nitrogen (N), total and bicarbonate phosphorus (P), and on the survival and relative growth rate of three species, Ipomea wolcottiana Rose, Lonchocarpus eriocarinalis Micheli and Caesalpinia eriostachys Benth, in a degraded seasonally dry tropical forest (SDTF) area. Our study year was unusually dry, with only half of the mean annual rainfall. Sixteen plots (5 • 6 m) for each of our four treatments, mulches with alfalfa (Medicago sativa L.) straw, forest litter (SDTF litter), polyethylene and bare soil (control), were used. In each plot, 20 tree saplings were planted of each species. The SVWC was higher in plots mulched with polyethylene than in bare soil plots. The soil pH did not change with mulching, and there were no differences between treatments in the concentrations of soil organic C, total N, NO 3 and total P. However, soil concentrations of NH 4 were highest in plots with alfalfa straw and of bicarbonate P in plots with polyethylene. Sapling survival was higher in polyethylene mulch plots than in other mulching treatments, in the order I. wolcottiana > C. eriostachys > L. eriocarinalis. Sapling survival under organic mulches, alfalfa straw and forest litter were similar, and lowest in bare soil. The relative growth rate followed the order L. eriocarinalis < C. eriostachys < I. wolcotiana, and the growth rate of all species was greatest under polyethylene mulch. We conclude that a combination of polyethylene mulch with species of high growth rate is best for restoring seasonally dry tropical areas.

&lt;p&gt;This research is a general reflection of the possible transmission not o... more &lt;p&gt;This research is a general reflection of the possible transmission not only of COVID-19 but of any influenza disease depending on environmental parameters such as solar radiation, air humidity and air temperature (vapor pressure deficit), evoking the Penman-Monteith model regarding the evaporation of the water that constitutes the small water droplets (aerosols) that carry the virus. In this case the evapotranspiration demand of the atmosphere with which it can be deduced that the spread of the disease will be higher in those places with less evaporative demand, that is, high air humidity and / or low temperatures, and / or low radiation intensities, and vice versa. It can also be deduced that the hours of greatest potential contagion are the night hours, while those with the lowest risk are between 2:00 p.m. and 4:00 p.m. On the other hand, in those rooms with low temperatures the contagion would be more effective. So, considering that the drops produced by a sneeze, by speaking or breathing can go beyond two meters away, it is roughly explained that the use of face masks and keeping a safe minimum distance of two meters can limit transmission of viruses and / or infections. However, this practice is not entirely safe as the environment can play an important role. What is recommended to reduce the spread of these pathogens is to produce high evaporative demands: increasing solar radiation, and increasing air temperature and reducing air humidity, which is practice that can be effective in closed rooms.&lt;/p&gt;

Theoretical and Applied Climatology, 1991

International Journal of Biometeorology, 1991

Agricultural and Forest Meteorology, Oct 1, 1986

A series of micrometeorological measurements were taken throughout the year in shaded and open-gr... more A series of micrometeorological measurements were taken throughout the year in shaded and open-grown coffee plantations in the central region of the state of Veracruz, Mexico. The average maximum and minimum air temperatures at the open plantation were 5.4-+ 1.5°C higher and 1.5-+ 0.2°C lower, respectively, than in the shaded plantation. Thermal amplitude increased 1.8-fold when shade trees were removed. Vapour pressure deficit was on average 0.2 kPa and Pichd evaporation was 40% higher at the open plantation. These results indicate that the change in micrometeorological factors resulting from the removal of shade trees could have an important impact on the physiology of the crop.

Revista Mexicana de Ciencias Agrícolas, Oct 1, 2011

It's concluded that, the presence of climate change is evident in the studied region even if it i... more It's concluded that, the presence of climate change is evident in the studied region even if it is not manifested in all the climatic parameters.

Terra Latinoamericana, 2006