Precipitação efetiva e interceptação em Caxiuanã, na Amazônia Oriental

Abstract

The present work was carried out at the Ferreira Penna Scientific Station, in the Caxiuanã National Forest, Melgaço, Pará, Brazil (01º 42" 30"S; 51º 31" 45"W; 60 m a.s.l.). The studied region is an upland forest with closed vegetation and a mean canopy height of 35 m although some trees can be 50 m high. The species density is between 450 and 550 plants per hectare. The aim was to quantify the net precipitation, throughfall, stemflow and rain interception by vegetation, from March to December of 2004. For the throughfall measurements 25 rain gauges were randomly distributed in an one hectare area subdivided in one hundred parcels of 10 x 10 m, while the stemflow was measured on seven trees with a stem diameter at breast height representative of the area. The results showed values of net precipitation of 905.4 mm, throughfall of 885.4 mm, stemflow 20 mm and rain interception of 248 mm,corresponding respectively to 78.5%, 76.8%, 1.7% e 21.5% of the total precipitation above the canopy which was 1,153.4 mm for the study period.