El microclima en una casa de sombra: palmas y Zamia como indicadores de aclimatación a la luz
Fecha
1999-2002
Autores
Gutiérrez Marco Vinicio
Jiménez Kenneth
Soto, Dagoberto
Alpízar, Melvin
Chinchilla, Cristina
Título de la revista
ISSN de la revista
Título del volumen
Editor
Universidad de Costa Rica
Resumen
Se compararon algunas variables microclimáticas medidas simultáneamente en el interior y en el exterior de una casa de sombra de 720 m2, ubicada en la Estación Experimental Fabio Baudrit Moreno en Barrio San José de Alajuela (840 msnm), construida con un techo compuesto de materiales de sarán que generaron seis regímenes de luz en el interior (40% a 80%). Se utilizaron además nueve especies de palmas y una especie de Zamia como indicadores biológicos de aclimatación a la luz, a las que se les midió el área, el grosor y el contenido foliar de Nitrógeno. Los materiales de sarán cumplieron solo parcialmente con las especificaciones descritas por los fabricantes en cuanto a sus propiedades de intercepción de luz. La temperatura y la humedad relativa del aire en el interior de la casa de sombra no difirieron de los valores registrados en el exterior, lo que sugiere que la modificación de estas variables microclimáticas es importante solo en casas de sarán grandes. En contraste, la temperatura del suelo fue significativamente afectada por el régimen de sombra, lo que resultó en mayores temperaturas absolutas y mayores fluctuaciones diurnas en el suelo expuesto a 40% de intercepción de luz comparado con el de 80%. La distribución espacial de la lluvia también fue alterada significativamente en el interior de la casa de sombra como resultado de la orientación cóncava de la mayoría de los techos. Cuatro de las 10 especies vegetales utilizadas como indicadores de aclimatación a la luz no se establecieron a plena exposición solar, y la mayoría de las especies alcanzaron mayor área foliar a porcentajes de intercepción de luz menores a 70-80%. Se discuten las causas y las implicaciones de los cambios microclimáticos encontrados en las casas de sombra pequeñas, y se recomiendan modificaciones arquitectónicas de las casas de sombra en función de los propósitos del ambiente protegido.
Shadehouses are one of the most common types of sheltered environments employed in tropical regions. The microclimatic modifications induced by these structures inside the shadehouse, their effects on the plants grown, and the relation between the architectural and functional characteristics of the shadehouses, remain unexplored. We measured the microclimate inside and out of a shadehouse of 720 m2, built at the Fabio Baudrit Experiment Station, University of Costa Rica. The roof designed with different shade materials created six light regimes inside the tent. We measured specifically: solar radiation, air temperature and humidity, rainfall spatial distribution, and soil temperature at 5, 10 and 15 cm depth. In addition, we evaluated plant acclimation to different light regimes by growing nine palm and a Zamia species under seven light regimes, including the control. The saran materials evaluated in this study complied only partially with the specifications provided by the manufacturers. Air temperature and relative humidity inside the shadehouse did not differ from the outside values, supporting early indications that changes in those variables are important only in large shadehouses. In contrast, soil temperature was significantly affected by the light regimes imposed. Higher values and larger fluctuations of soil temperature were observed at 40% than at 80% shade. Rainfall distribution inside the shadehouse was also significantly modified as a result of the predominantly concave orientation of the saran panels employed in shadehouse construction. Four out of the 10 species used as indicators of acclimation to light were not establish under full sun exposure, and most of the species exhibited their larger leaf area under shade regimes lower than 70-80%. The causes and implications of the environmental features observed inside small shadehouses are discussed, and modifications of the architectural design of shadehouses are proposed.
Shadehouses are one of the most common types of sheltered environments employed in tropical regions. The microclimatic modifications induced by these structures inside the shadehouse, their effects on the plants grown, and the relation between the architectural and functional characteristics of the shadehouses, remain unexplored. We measured the microclimate inside and out of a shadehouse of 720 m2, built at the Fabio Baudrit Experiment Station, University of Costa Rica. The roof designed with different shade materials created six light regimes inside the tent. We measured specifically: solar radiation, air temperature and humidity, rainfall spatial distribution, and soil temperature at 5, 10 and 15 cm depth. In addition, we evaluated plant acclimation to different light regimes by growing nine palm and a Zamia species under seven light regimes, including the control. The saran materials evaluated in this study complied only partially with the specifications provided by the manufacturers. Air temperature and relative humidity inside the shadehouse did not differ from the outside values, supporting early indications that changes in those variables are important only in large shadehouses. In contrast, soil temperature was significantly affected by the light regimes imposed. Higher values and larger fluctuations of soil temperature were observed at 40% than at 80% shade. Rainfall distribution inside the shadehouse was also significantly modified as a result of the predominantly concave orientation of the saran panels employed in shadehouse construction. Four out of the 10 species used as indicators of acclimation to light were not establish under full sun exposure, and most of the species exhibited their larger leaf area under shade regimes lower than 70-80%. The causes and implications of the environmental features observed inside small shadehouses are discussed, and modifications of the architectural design of shadehouses are proposed.