Variability of annual rainfall partitioning for different sites and forestcovers in Chile

Precipitation, throughfall, stemflow and interception losses were determine d in Chile on 29 research plots grouped in nine research sites, covering a wide range of rainfall zones, forest types, species, ages and densities. Al l the data are presented and analyzed on a 12-month time base. Throughfall varied between 55 and 86% of precipitation (P) and although it was higher i n coniferous stands than in broadleaved forests the differences were not st atistically significant. Stemflow varied from 1 to 13% of P in coniferous s tands and between 1 and 8% of P in broadleaved forests. Stemflow for indivi dual trees was higher under high annual rainfall and in low dense forests, and decreased when annual precipitation reduced and forest density increase d. In broadleaved stands interception losses (I) ranged from 204 to 1097 mm /year while in coniferous forests I showed a narrower range of variation fr om 199 to 579 mm/year. Because the final effect of the replacement of nativ e forests by plantations upon water yield also depends on transpiration and other evaporation losses, it was not possible to conclude that this substi tution will increase water availability. In a Monterey pine stand intercept ion losses increased with the age of the forest because of the tendency for the branches of this conifer to become horizontal, thus increasing interce ption capacity and decreasing stemflow. In a native forest that had reached its climax state interception losses decreased during nine years of measur ement associated with the continuous reduction of interception capacity of the dense bamboo understorey. (C) 2001 Elsevier Science B.V. All rights res erved.