Fenología y producción de frutos de plantaciones de siricote (Cordia dodecandra A. DC.) bajo tres tipos de manejo en Xmatkuil, Yucatán, México

Phenology of a species allows us to understand and predict flowering and fructification times useful in the management of deciduous tropical trees. This study was performed in three plantations (P1, P2 and P3) of Cordia dodecandra with different kind of management (P1, pruning, irrigation, weeding; P2, weeding; P3, without management), established in 2002 at Xmatkuil, Yucatan. The evaluation covered the period of September (2011)-August (2012). The phenology was determinated once a month using Fournier method. Production was assessed by harvesting and counting all fruit of all trees from each orchard and fruit quality was weighed and measured the length and width of a sample (n = 20) and obtained the moisture content of the same putting them in a dryer at 60°C. Results showed that P1 presented 100% leaves in September 2011, and during the period November 2011- August 2012. The percentage of leaves decreased to 25% only in the month of October 2011. P2 y P3 lost all their leaves during the period December-March. Regarding flowering, P1 presented flowers in percentage of 25% most of the year except for the months of June and July when the presence of any floral structure was recorded. The peak was observed in March. The other two plantations, P2 and P3, bloomed during the dry season (December to May). P2 presented a peak in February and P3 in March. Fructification in P1 showed in the months of October, November and January but the maximum production was in May, P2 in the months of January to June, showing a peak in March and P3 from February to May with a maximum in the month of May. The highest production and fruit quality was recorded in P1.El estudio de la fenología de las especies permite entender y predecir épocas de floración y fructificación útiles en el manejo de árboles tropicales caducifolios. La presente investigación se realizó en tres plantaciones de Cordia dodecandra (P1, P2 y P3) establecidas en el año 2002 en Xmatkuil, Yucatán, que se han manejado de diferente manera: poda, riego y deshierbe (P1); deshierbe (P2) y sin manejo (P3). Los objetivos de este trabajo fueron evaluar la fenología, la producción y calidad de los frutos de tres plantaciones. La fenología se determinó una vez al mes, utilizando el método de Fournier. La producción se evaluó cosechando y contabilizando la totalidad de frutos de todos los árboles de cada plantación, y la calidad del fruto, mediante el peso y medidas del largo y ancho de una muestra (n=20) de cada plantación. Además, se obtuvo el porcentaje de humedad de los mismos poniéndolos en una secadora a 60° C. Los resultados mostraron que P1 presentó hojas en porcentajes del 100% en septiembre 2011, en octubre disminuyó y el porcentaje de hojas fue de 25% y posteriormente en el periodo de noviembre 2011-agosto 2012 nuevamente hubo 100% de hojas. P2 y P3, perdieron sus hojas durante el periodo diciembre-marzo. Respecto a la floración, P1 presentó flores en porcentajes del 25% durante casi todo el año, a excepción de junio y julio, en los que no se registró la presencia de ninguna estructura floral; el pico máximo se observó en marzo. Las otras dos plantaciones sólo tuvieron floración durante la época de sequía (diciembre-mayo). En el mes de febrero, P2 presentó un pico máximo y P3 en marzo. La presencia de frutos en P1 se observó en octubre, noviembre y enero, incrementándose hasta obtener un pico máximo en mayo. En P2 la fructificación se observó de enero-junio y presentó un pico máximo en marzo, y en P3, de febrero-mayo con pico máximo en mayo. La mayor producción y calidad de frutos se registró en P1 presentando diferencias significativas

The tropical forest and the ecosystem services it provides. Perceptions of a Mayan community in southern Yucatan, Mexico

Las comunidades humanas tienen una estrecha relación con los ecosistemas que las rodean, de ellos obtienen beneficios tangibles como insumos y alimentos, e intangibles como la tranquilidad y seguridad de sentirse protegidos. Conocer y registrar historias, entornos y percepciones de quienes manejan los recursos, favorece la elaboración de planes de gestión que satisfagan las necesidades comunitarias y conserven los ecosistemas. Este trabajo analiza las percepciones de los habitantes de una comunidad maya en relación con los servicios ecosistémicos que la selva circundante les brinda. Se aplicaron entrevistas semiestructuradas en 41 hogares y se realizaron talleres participativos con ocho informantes clave. Se elaboró una línea de tiempo, mapas de recursos presentes y futuros, y se registró la percepción de los servicios ecosistémicos. Eventos como la conformación de grupos de trabajo y participación en convocatorias gubernamentales han marcado positivamente la vida de los pobladores. Los servicios materiales obtuvieron la mayor valoración. También fueron relevantes los servicios no materiales como el paisaje y la estética. Reconocen que la selva es un espacio que les brinda refugio, paz, tranquilidad y recursos para su subsistencia, por ello la conservación de sus elementos es eje fundamental en cualquier estrategia de manejo que propongan.Human communities have a close relationship with the ecosystems that surround them, as they provide them with benefits ranging from inputs and food to the peace of mind and security of feeling protected. It is important to know and record the stories, environments, and perceptions of those who manage the resources, as this will make it possible to develop management plans that satisfy community needs and at the same time conserve the ecosystems. This study analyzes the perceptions of a Maya community in relation to the ecosystem services that the tropical forest provides them. Semi-structured interviews were conducted with representatives of 41 households, followed by participatory workshops with eight key informants. A timeline and maps of present and future resources were created, and the perception of ecosystem services was recorded. Actions such as the formation of working groups and participation in governmental calls for proposals have had a positive impact on the lives of the villagers. Material services were the most highly valued; however, non-material services such as the landscape and the aesthetics of their environment were also relevant. Dialogue with the communities is a fundamental part of the planning and implementation of strategies linked to the context of each environment, which should be aimed at solving local problems.Esta investigación fue financiada por el Consejo Nacional de Ciencia y Tecnología (CONACyT) a través del proyecto Gestión de agroecosistemas sustentables en el sur de Yucatán (M0037-2019-305870)

Assessment of population structure and management of Cordia dodecandra A. DC. in homegardens and tropical forest in Yucatan, Mexico

Cordia dodecandra A. DC. is an arboreal component of forests and Maya homegardens in the state of Yucatan, México. Changes in land use and landscape fragmentation have led to declines in wild populations. Understanding this species’ population structure is relevant to determining the current state of its populations and proposing strategies for its conservation. The population structure of C. dodecandra in forest and homegardens in Yucatan, and the management practices associated with the species were documented with interviews. Relative importance of the tree species in the associated vegetation was estimated. Seedling density (< 1m of height) was higher in the homegardens than the forest with an evident decrease in the density of juvenile individuals caused by practices such as weeding. In contrast, the forest contained a greater number of adult and larger individuals than in the homegardens. Individual C. dodecandra were taller in the forest, but those in the homegardens had a larger diameter at breast height. Although it has multiple uses (e.g. food, ornamental, wood) the C. dodecandra in homegardens received only minimal maintenance, possibly threatening its permanence in this system. This is concerning since the homegardens function as de facto germplasm banks for this species. Highlights Cordia dodecandra trees from homegardens have a diameter at breast height (DBH) larger than those that live in the dry forest. Cordia dodecandra trees in tropical dry forests, are taller than in homegardens. Succession data showed that tropical dry forests have more adult trees of Cordia dodecandra, and homegardens have a higher density of seedlings.Cordia dodecandra A. DC. is an arboreal component of forests and Maya homegardens in the state of Yucatan, México. Changes in land use and landscape fragmentation have led to declines in wild populations. Understanding this species’ population structure is relevant to determining the current state of its populations and proposing strategies for its conservation. The population structure of C. dodecandra in forest and homegardens in Yucatan, and the management practices associated with the species were documented with interviews. Relative importance of the tree species in the associated vegetation was estimated. Seedling density (< 1m of height) was higher in the homegardens than the forest with an evident decrease in the density of juvenile individuals caused by practices such as weeding. In contrast, the forest contained a greater number of adult and larger individuals than in the homegardens. Individual C. dodecandra were taller in the forest, but those in the homegardens had a larger diameter at breast height. Although it has multiple uses (e.g. food, ornamental, wood) the C. dodecandra in homegardens received only minimal maintenance, possibly threatening its permanence in this system. This is concerning since the homegardens function as de facto germplasm banks for this species. Highlights Cordia dodecandra trees from homegardens have a diameter at breast height (DBH) larger than those that live in the dry forest. Cordia dodecandra trees in tropical dry forests, are taller than in homegardens. Succession data showed that tropical dry forests have more adult trees of Cordia dodecandra, and homegardens have a higher density of seedlings

MODELO TERMOELÉCTRICO DE UNA BATERÍA RECARGABLE EN MATLAB-SIMULINK ( THERMOELECTRIC MODEL OF A RECHARGEABLE BATTERY IN MATLAB-SIMULINK)

Resumen Este artículo presenta la implementación computacional del modelo termoeléctrico de una batería de iones de litio (Li-ion), así como los resultados obtenidos de este modelo bajo distintas condiciones de transferencia de calor por convección. La implementación computacional del modelo desarrollado se realizó usando Matlab/Simulink. El modelo se empleó para investigar el desempeño de la batería, este modelo desarrollado se basó en los parámetros físicos de las baterías eléctricas del Nissan Leaf, i.e. voltaje nominal, capacidad eléctrica, área de convección y masa. La carga demandada de la batería fue 1.5 Amperes a una temperatura ambiente de 20°C durante 3600 segundos. Estas condiciones se mantuvieron para tres diferentes valores de coeficiente de transferencia de calor por convección: 2 y 25 W/m2 K para convección libre, mientras que para convección forzada se usan los valores 25 y 250 W/m2 K. Los resultados correspondientes mostraron valores de entre 31°C y 36°C para la correspondiente temperatura interior de la celda. Palabras clave: Batería Recargable, Modelo termoeléctrico, Matlab-Simulink Abstract This article presents the computational implementation of the thermoelectric model of a lithium-ion (Li-ion) battery, as well as the results obtained from this model under different convective heat transfer conditions. The computational implementation of the developed model was carried out using Matlab / Simulink. The model was used to investigate the performance of the battery, this developed model was based on the physical parameters of the electric batteries of the Nissan Leaf, i.e. nominal voltage, electrical capacity, convection area and mass. The battery charge demanded was 1.5 Amps at an ambient temperature of 20 ° C for 3600 seconds. These conditions were maintained for three different values ​​of heat transfer coefficient by convection: 2 and 25 W / m2 K for free convection, while for forced convection the values ​​25 and 250 W / m2 K are used. The corresponding results showed values between 31 ° C and 36 ° C for the corresponding internal cell temperature. Keywords: Rechargeable Battery, Thermoelectric Model, Matlab-Simulink

Evaluación de tres leguminosas como coberturas asociadas con maíz en el trópico subhúmedo

Evaluación de tres leguminosas como coberturas asociadas con maíz en el trópico subhúmedo. El objetivo fue evaluar el potencia l de tres leguminosas como coberturas para mejorar el sistema de producción de maíz. Se evaluaron cuatro tratamie ntos: 1) maíz solo; 2) maíz y Phaseolus lunatus de ciclo corto de semilla blanca 3) maíz y Phaseolus lunatus de ciclo largo de semilla blanca y 4) maíz y frijol terciopelo (Mucuna sp.) en un diseño experimental de bloques al azar, con cuatro réplicas, durante cuatro ciclos de cultivo (1999-2002) en Yucatán, México. Se midió la biomasa de cultivos, pH, N total, mineralización potencia l anaerobia del nitrógeno, evolución del CO 2, potasio (K), fósforo (P) y materia orgánica del suelo, biomasa y frecuencia de arvenses. La cantidad de rastrojo en los tratamie ntos con leguminosas fue: 3436, 3425 y 4018 kg MS /ha para el primero, segundo y tercer año, respectivamente. El nitrógeno aportado por los rastrojos al maíz fue 25,8; 31,9; 52,8 y 43,4 kg/ha para los tratamie ntos 1, 2, 3 y 4, respectivamente. El rendimie nto de grano de maíz fue en promedio 841, 843 y 460 kg MS /ha para el primero, segundo y tercer ciclo, respectivamente; sin diferencia s entre tratamie ntos. En el tercer ciclo, el frijol terciopelo disminuyó la biomasa de arvenses de 126 a 58 g MS /m2. Las coberturas ejercieron poca influencia en las variables de suelo y rendimie nto de grano de maíz

Source water, phenology and growth of two tropical dry forest tree species growing on shallow karst soils

Seasonally dry tropical forests are dominated by deciduous and evergreen tree species with a wide range of leaf phenology. We hypothesized that Piscidia piscipula is able to extend leaf senescence until later in the dry season due to deeper and more reliable water sources than Gymnopodium floribundum, which loses leaves earlier in the dry season. Physiological performance was assessed as timing of leaf production and loss, growth, leaf water potential, depth of water uptake determined by stable isotopes, and leaf stable isotopic composition of carbon (δ¹³C) and oxygen (δ¹⁸O). P. piscipula took water primarily from shallow sources, whereas G. floribundum took water from shallow and deep sources. The greatest variation in water sources occurred during the onset of the dry season, when G. floribundum was shedding old leaves and growing new leaves, but P. piscipula maintained its leaves from the previous wet season. P. piscipula showed greater relative growth rate, greater leaf expansion rates, and more negative predawn and midday water potentials than G. floribundum. P. piscipula also exhibited greater leaf organic δ¹³C and lower δ¹⁸O values, indicating that the decrease in photosynthetic carbon isotope discrimination was associated with greater stomatal conductance and greater photosynthesis. Our results indicate that the contrasting early and late dry season leaf loss phenology of these two species is not simply determined by rooting depth, but rather a more complicated suite of characteristics based on opportunistic use of dynamic water sources, maximizing carbon gain, and maintenance of water potential during the dry season

PHENOLOGY AND FRUIT PRODUCTION OF SIRICOTE (Cordia dodecandra A. DC.) PLANTATIONS UNDER THREE KINDS OF MANAGEMENT AT XMATKUIL, YUCATAN, MEXICO

Phenology of a species allows us to understand and predict flowering and fructification times useful in the management of deciduous tropical trees. This study was performed in three plantations (P1, P2 and P3) of Cordia dodecandra with different kind of management (P1, pruning, irrigation, weeding; P2, weeding; P3, without management), established in 2002 at Xmatkuil, Yucatan. The evaluation covered the period of September (2011)-August (2012). The phenology was determinated once a month using Fournier method. Production was assessed by harvesting and counting all fruit of all trees from each orchard and fruit quality was weighed and measured the length and width of a sample (n = 20) and obtained the moisture content of the same putting them in a dryer at 60°C. Results showed that P1 presented 100% leaves in September 2011, and during the period November 2011- August 2012. The percentage of leaves decreased to 25% only in the month of October 2011. P2 y P3 lost all their leaves during the period December-March. Regarding flowering, P1 presented flowers in percentage of 25% most of the year except for the months of June and July when the presence of any floral structure was recorded. The peak was observed in March. The other two plantations, P2 and P3, bloomed during the dry season (December to May). P2 presented a peak in February and P3 in March. Fructification in P1 showed in the months of October, November and January but the maximum production was in May, P2 in the months of January to June, showing a peak in March and P3 from February to May with a maximum in the month of May. The highest production and fruit quality was recorded in P1.</p

Análisis de la estructura vegetal de huertas frutícolas del sur de Yucatán, México

The aim of this study was to know the tree structure of the irrigation unit, whose area is 65 hectares divided into 65 plots of 10 000 m² each, in which a sample of 180 m² per plot was performed. 1565 individuals which belong to 40 species, 28 genera and 19 families, were recorded; its horizontal distribution is divided into four canopies, the highest covered species such as Cocos nucifera, Manilkara zapota and Cedrela odorata with heights ranging from 9 to 10 m. The results from structural indices place Sabal yapa and Citrus sinensis as the most important species. Five uses of land were recognized of which the highest value obtained in diversity were obtained by agroforestry plots. The irrigation unit is divided into different agroforestry systems and each one of them has different species which gives them a unique structure.El objetivo del presente estudio fue el conocer la estructura arbórea de la unidad de riego, cuya extensión es de 65 ha dividida en 65 parcelas de 10 000 m² cada una, en las cuales se realizó un muestreo de 180 m² por parcela. Se registraron 1 565 individuos los cuales pertenecen a 40 especies, 28 géneros y 19 familias, su distribución horizontal se divide en cuatro doseles, el más alto abarcó especies como Cocos nucífera, Manilkara zapota y Cedrela odorata con alturas de entre 9 y 10 m. Los resultados de los índices estructurales ponen a Sabal yapa y Citrus sinensis como las especies más importantes. Se reconocieron cinco usos de suelo de los cuales el valor más alto en diversidad lo obtuvieron las parcelas agrosilvopastoriles. La unidad de riego se divide en diferentes sistemas agroforestales y cada uno de ellos tiene diferentes especies lo que le otorga una estructura única