Evapotranspiration and control mechanisms in managed Amazonian forest in, Pará, Brazil.

This work examines whether management causes changes in evapotranspiration (ET) surface conductance (gs), aerodynamic conductance (ga) and the decoupling factor (Ω) in managed and natural forest sites in a tropical rain forest in the Amazon. The study was conducted in the Tapajós National Forest (FNT) in managed (logged) and natural (unlogged) forests, which have micrometeorological towers for data capture. For ET estimation, the Penman-Monteith (PM) and Eddy Covariance (EC) equations were used. The models were significantly different only for unlogged (PM 134.9±15.9 mm.month-1 and EC 100.9±11.1 mm.month-1), while the means of the logged site were PM 111.1±15.7 mm.month-1 and EC 108.5±18.3 mm.month-1. Each area has different characteristics for the surface variables, ga, gs and Ω, and therefore the sites were different from each other for the study variables. However, logged ET did not differ for the PM, while EC decreased in the year after the management intervention, and was then followed by an increase.