Impacto da substituição da mata atlântica alagoana por cana-de-açúcar no albedo

Abstract

The Atlantic Forest today is considered the most devastated native vegetation area in Brazil. It’s one of the five most diverse biomes in the world. Studies on the tropical forests microclimate help to understand how this biome has been suffering from climate change. Solar radiation is all electromagnetic radiation coming from the sun that reaches the planet, considered the main source of energy for many physical-chemical and biological processes that occur in the Earth-Atmosphere system. The albedo is defined as the ratio of the flux of radiation reflected by a surface in all directions and the flux incident on earth. A detailed study of how albedo varies in space and time, its influence on climate and vegetation dynamics, because with the increase or decrease of the albedo, there is an energy and radiative imbalance on the surface of the Earth. The general objective of this work is to analyze the albedo variability with the substitution of the Atlantic forest for sugarcane in the state of Alagoas, as well as to study the possible variation that the vegetation change cover can cause in the local microclimate as to the energy balance. The study area comprehend two experimental sites, one in an Open Ombrophylous Forest with transition to Semideciduous Seasonal Forest and the other in the middle of a cane field of the Utinga Leão Plant. Data from January to December / 2014, however, the data of solar radiation and albedo in the Canavial are related to the period of regrowth and development of the crop until the harvest phase, from January to October / 2014. The measurement of the experimental data of Global Solar Radiation (Rg) and surface albedo (α) were made using pyranometers installed in the micrometeorological stations in the forest and in the cane field. In the two stations, the measurements were performed every 20 seconds by CR10X dataloggers and their averages stored every 10 minutes. In the albedo data collection, two pyranometers were used with their domes facing downwards. In the albedo data collection, two pyranometers were used with their domes facing downwards. Ten - minute rainfall data were used for Canavial, yielded and measured by the automatic agrometeorological station of the Agrarian Sciences Center of the Federal University of Alagoas (CECA/UFAL); Climatic norms referring to Coruripe and Maceió (points closest to the respective sites) made available by the National Institute of Meteorology - INMET. After data consistency, the hourly, daily, monthly and annual averages of the albedo values were calculated. Subsequently, the zenith angle (Z) and the atmospheric transmittance index (Kt) were calculated to verify their relationship with the albedo. The forest albedo was, on average, (15.2%) and sugarcane (23.2%). In rainforest and rainy season (May to August) and transition (rainy-dry), the periods with the highest occurrence of rain are in the morning and at night, with the rain being the longest in the forest, intense. In the rainy season, the albedo of the forest was, on average, 14.8% and in the dry season 15.4%. For canevial, in the rainy season, the average of the albedo was 22.3% and 24.9% for the dry season. The forest albedo was, on average, (15.2%) and sugarcane (23.2%). There is an increase in the albedo of 34.5% when it replaces the forest with sugarcane.