Interceptação da chuva em floresta estacional decidual em Santa Maria, RS

Abstract

In areas of native forests, interception of rain precipitation trhough the vegetation is an important variable of the water balance. This research analyzed the interception process in two areas of deciduous forest at Santa Maria RS; along river Vacacaí Mirim. The variables monitored from March / 2013 to March / 2014 were: incident precipitation, stemflow and throughfall. The incident precipitation was monitored by a rain gauge type vats-tipper and a rain gauge, and also checked by INMET. The internal precipitation was monitored in both areas (I and II), with dimensions of 12 m x 50 m and 13 m x 45 m respectively. The stakes were installed at 40 or 60 cm of height. In both areas 101 stakes were allocated for disposal of 40 interceptômetros. Tere were 20 of these remained fixed and 20 were rotated. The stemflow was determined by monitoring the flow in three trees chosen within each area and the interception was calculated as the difference between precipitation and the sum of throughfall and stemflow. The highest interception was found in the area I. The stemflow in area II was lower as reported by other authors, showing that this variable can not be ruled of interception study. The internal precipitation variation ranges and interception were similar to those reported in other studies. The average of rainfall for the internal fixed and mobile interceptômetros was not significant. The interception in the experimental area I was 46.63% of the incident rainfall and the experimental area II was 43.93% of the incident rainfall. The results showed that the interception is a key component of the hydrological cycle and generally underestimated by hydrological models. The research concludes that the study of interception in soils with forest cover is essential for determining the water balance of an area.