Avaliação do microclima em área de caatinga e área reflorestada com algaroba no semiárido.

Abstract

In recent years some areas of native vegetation in northeastern Brazil (NEB) have begun to be reforested with mesquite. The present study makes a comparison of microclimates in the areas of caatinga and reforested with mesquite, from January - February and June July 1996 in Serra Negra do Norte - RN. Radiation and energy balances, air temperature above and within the canopies, specific and relative humidity, wind speed and water transfer to the atmosphere were analyzed for these areas using the Bowen Ratio method. . Data acquisition was performed with two dataloggers, which made it possible to perform readings at intervals of 1 in 1 second and then to calculate averages every 5 minutes. The latent and sensitive heat fluxes during the rainy season represented about 68.2% and 27.0% of the radiation balance (Rn) in the caatinga area, while in the mesquite area represented 80.3% and 9.6% of Rn. After the rainy season these flows in the caatinga represented 93.3% and 4.0% of Rn and in mesquite 92.8% and 3.0%, respectively. The Brunt equation during the rainy season better estimated the longwave radiation from the atmosphere (L4-) in both areas. After the rainy season the Satterlund equation estimated better L-l for caatinga area and Idso equation for the mesquite area. In terms of water depth, the caatinga and mesquite areas in the first period transferred the equivalent of 4.6 and 5.1mm / day, while in the second period, the blades corresponded to 4.7 and 4.6mm / day. , respectively. The air temperature within the canopy in both periods was higher in the caatinga area during the day and with slight variations at night. Due to the scarcity of water in the semi-arid NEB region, it is not advisable to set up mesquite near small water sources, as this plant has a large capacity to transfer water from underground to the atmosphere.