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The complex environment within a crop canopy leads to a high variability of the air temperature within the canopy, and, therefore, air temperature measured at a weather station (WS) does not represent the internal energy within a crop. The objectives of this study were to quantify the difference between the air temperature measured at a standard WS and the air temperature within a six-year-old vineyard (cv. Chardonnay) and to determine the degree of uncertainty associated with the assumption that there is no difference between the two temperatures when air temperature is used as input in grapevine models. Thermistors and thermocouples were installed within the vine canopy at heights of 0.5 m and 1.2 m above the soil surface and immediately adjacent to the berry clusters. In the middle of the clusters sensors were installed to determine the temperature of the air surrounding the clusters facing east and west. The data were recorded within the canopy from December 2015 to June 2017 as well as at the standard WS that was installed close to the vineyard (410 m). Significant differences were found between the air temperatures measured at the WS and those within the vineyard during the summer when the average daily minimum air temperature within the canopy was 1.2˚C less than at the WS and the average daily maximum air temperature in the canopy was 2.0˚C higher than at the WS. The mean maximum air temperature measured in the clusters facing east was 1.5˚C higher and west 4.0˚C higher than the temperature measured at the WS. Therefore, models that assume that air temperature measured at a weather station is similar to air temperature measured in the vineyard canopy could have greater uncertainty than models that consider the temperature within the canopy.

<p>La zona cafetera colombiana está ubicada enteramente en el hemisferio norte, entre los 1 y 11° grados de latitud, sobre la cordillera de los Andes. Esta condición (ecuatorial andina) ha hecho que se dé por sentado que la variación temporal de la temperatura es mínima y que por ello, en su mayor parte la variabilidad de este elemento es espacial, atribuible casi exclusivamente a los cambios en altura sobre el nivel del mar. En este estudio se exploran factores de variación alternas, que muestran cómo, además de la altitud, otros factores, como la latitud, la zona de convergencia intertropical, El Niño Oscilación del Sur y el Cambio Climático, inciden sobre esta variable climática, que a su vez ejerce un papel fundamental sobre las plantaciones de cafeto.</p>

<p>La baja oferta de alimento, problema que aqueja a un alto porcentaje de la población ganadera de Colombia, se asocia,en gran medida, a la selección equivocada de especies forrajeras; es decir, con frecuencia las especies sembradas no están adaptadas a la oferta mbiental de una región en particular. Para atenuar el riesgo de la baja oferta forrajera, sin incurrir en costos asociados al cambio de la oferta ambiental, es preciso aprovechar las habilidades fisiológicas de las especies para hacer frente al ambiente donde crecen. Para ello, se desarrolló un sistema de toma de decisiones para la selección de especies forrajeras (STDF), herramienta básica en la transferencia de tecnología agropecuaria que tiene por objetivo atenuar la incertidumbre al definir las especies forrajeras aptas para un ambiente determinado. El sistema se desarrolló a partir de fundamentos básicos de la gestión del conocimiento, por lo que en su construcción no se diseñó ningún experimento, sino que se aprovechó la información existente en el país, proveniente de evaluaciones realizadas en el pasado. A partir de la información recabada, se generó una base de datos de requerimientos de las especies, de tal forma que el sistema, desarrollado e implementado sobre ASP.NET en C# y base de datos SQL Server, relaciona ambientes y requerimientos de cultivos. Dicho sistema permite a los usuarios realizar procesos de búsqueda y selección de especies de pastos y forrajes de acuerdo con las condiciones edafoclimáticas de una determinada finca o región, de manera sencilla y amigable.</p>

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This paper presents the conceptualization, methodological adjustment and experimental application of the micrometeorological technique eddy covariance - EC, to measure energy, water vapor and CO2 fluxes in two coffee agroecosystems: the first under full sunlight, and the second under shade, both with equatorial Andean hillslope conditions. With a footprint and fetch calculation, the required distance from the edge of the field in the prevailing wind direction to the EC tower is three times higher under shade than full sun. The shaded agroecosystem reached maximum average carbon fixation rates of 21.26 ± 2.469 μmolCO2.m-2s-1 ( = 0.05) (61% higher than under 100% sunlight) which gives a high carbon sink capacity to the association of coffee plants with shading Pigeon peas (Cajanus cajan L). The average evapotranspiration rate was 2.33 ± 0.0102 mm.d-1 ( = 0.05) and 2.08 ± 0.00732 mm.d-1 under shade and 100% sunlight, respectively. The proportion of net radiation that reached the soil was 2% under shade and 4% under 100% sunlight. Likewise, the soil energy loss during the night was lower under shade, indicating less day-night temperature range in the latter agroecosystem. The methodological adjustment and the results of this first work using EC in Colombian coffee plantations, contribute to the development of reliable research regarding gas and energy exchanges between the atmosphere and ecosystems in conditions of the equatorial Andean hillslope.

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