Comparison between microclimatic variables in open and forest sites at Mata Atlântica Biome, Southern Brazil

Abstract

In the subtropical region of Brazil, the environment is naturally characterized by the hot and humid climate. These conditions are preponderant factors for the occurrence of forest formation, the Atlantic Forest biome. Any non-natural environment can receive negatively the local meteorological condition. Forests act as regulators mitigating the meteorological and microclimatic indices. Three-year data of two meteorological stations were used, one in an open pasture area and one under the canopy of a forest fragment of the dense Ombrophilous forest (Mata Atlântica) in advanced stage of regeneration. Precipitation, relative air humidity, global radiation, air temperature, wind speed and soil temperature were monitored. Potential daily evapotranspiration was estimated by the Penman-Monteith equation (PM-FAO56) for both conditions. The forest area presented different meteorological conditions when compared to the open area (pasture). For example, forest canopy retained 41.2% of annual precipitation (lower surface drainage), the average daily air temperature was reduced by 9.5%, as well as the average wind speed by 87.6%, and mean radiation by 88.1%. Potential evapotranspiration was 89.1% higher in pasture. This value is corroborated by the annual average of air humidity which was 7.6% higher in the forest. The daily behavior of meteorological variables showed higher values in the pasture and around 15h, and lower in the forest at night. Except for the relative humidity that was the inverse. In pasture there are larger losses of water to the atmosphere. The forest environment, on the other hand, retains more water, forming a “microclimate” inside the forest canopy.