Balance Hídrico en Tres Plantaciones de Pinus radiata y una Pradera. II: Humedad del Suelo y Evapotranspiración

Abstract

Soil water content and amount of water consumed by évapotranspiration were studied in three plantations of Pinus radiata D. DON: 26 -year-old (density: 733 tree/ha), 9 -year-old with conventional management (density: 1392 tree/ha), 9 year-old tree-faming management (density: 443 tree/ha) and a natural meadow. The study area is located in Huape Tres Esteros, 20 km northeast from Valdivia (Lat. 39°48' S, Long. 73°14' W, Alt. 20 m).
Soil water content was measured with tensiometers and Bouyoucos plaster capsules, to a depth of 270 cm. Evapotranspiration was calculated from the changes of soil water content plus net precipitation (throughfall plus stemflow), during the period with no percolation.
During summer, soil water reserves were considerably decreased up to 250 cm of the soil in the three plantations, and up to 100 cm in the meadow. Evapotranspiration between October 1, 1982, and April, 1983, for adult, conventional and tree farming forest was 1,057; 1,009 and 999 mm. respectively, and 501 mm for the meadow between October 28 and April 21.
Evaportranspiration for the period of measurements, correspondinq to 76% in adult and conventional forests and 63% in tree—farming forest, as related to the annual net precipitation. For the period October 28 to April 21 it is 29 % for the meadow. For the period when the soil is saturated the treefaming forest shows the greated percolation, due to the minor interception that realizes this cover.