Caracterização dos impactos do desmatamento no microclima em Rondônia (RO) LBA 2002

Abstract

This work will discuss the possible climatic impacts of the replacement of native vegetation by pastures in western Amazonia (Rondônia) during the rainy season. The aim is to contribute to a better understanding of these impacts over the local microclimate, especially the surface energy balance. Data were collected during the LBA experiment in 2002 (Large Scale Biosphere-Atmosphere Experiment in Amazonia), being used the data between February and march of this year. Measurements were performed at two experimental sites, one within a native forest (10°5 S; 61° 55 W; 120 m) and the other in the area where forest has been replaced by pasture (10° 45 S; 62° 21 W; 290 m). The results showed that the temperature in the deforested area increased on average 0.88 ° C. The pasture area also was 11% drier, with winds of 2.3 ms-1 more intense. The net radiation was also lower in deforested area, 20.41 W.m-2 on average. In what concern the turbulent fluxes of sensible and latent heat, in the in the degraded area, H presented 13.16 W.m-2 higher, and LE was 38 W.m-2 inferior. This situation is reflected in the Bowen ratio, which averaged 0.59 higher. The amount of available energy converted in air heating (H/Rn) was of 39,41% in the pasture and11,18% in the forest. The amount of available energy converted in evaporation (H/LE) in the deforested area was only 31,6%, while in the native forest was 54%.