Avaliação da interceptação da precipitação pela vegetação na floresta nacional de Caxiuanã, Pará.

Abstract

The data for the present work were obtained in the Ferreira Penna Scientific Station, into the Caxiuanã National Forest, Melgaço, Pará, Brazil (01º 42’ 30”S; 51º 31’ 45”W; 60 m a.s.l.). The study region is an upland forest region with closed vegetation and canopy average 35 m high and some trees with 50 m high, the species density between 450 and 550 plants per hectare. The aims were to measure the precipitation above canopy, net precipitation, throughfall, stemflow and rain interception, the seasonal variability during rainy and drought periods and estimations for numerical modelling, from March to December of 2004. For the throughfall measurements were used 25 rain gauges randomly distributed into the one hectare area subdivided in 100 parcels of 10 x 10 m, while the stemflow were measured at 7 trees with stem diameter at breast height representative of the area. Studies 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 total precipitation above canopy which was 1153.4 mm for the studied period. The rain interception estimations were simulated within a good level using Rutter´s and Gash´s models. The Gash model overestimated in 17.3% (42.8 mm) for accumulated rain interception while the Rutter model overestimated only 0.5% (1.1 mm) for accumulated rain interception, both from March to December of 2004.