Uso e cobertura da terra e parâmetros biofísicos: análise do projeto de assentamento Assurini, Altamira-Pará, Brasil

Abstract

Changes in land use and cover and their impacts have been discussed by various governmental and scientific agencies around the world. In this context, the aim of this study was to assess the impact of the implementation of the Assurini settlement project and its land use dynamics on biophysical parameters such as the Normalized Difference Vegetation Index (NDVI), Surface Temperature (Ts) and Radiation Balance (Rn). These parameters were analyzed in areas of native and secondary vegetation, as well as in areas of pasture and degraded vegetation with bare soil. The research used orbital products from the Landsat 5 (TM) and Landsat 8 (OLI/TIRS) satellites, point 62 orbit 225, as well as meteorological data from the ERAS 5 platform, for the years 1996, 2006, 2011, 2017 and 2023, in which the data was processed on the Google Earth Engine - GEE platform. To collect land use and land cover data, remote sensing data managed in a Geographic Information Systems environment was used to process and generate the data. It was observed that NDVI showed a reduction over the years due to the decrease in native forest areas, while Ts showed an increase, especially in 2017 and 2023, due to the replacement of native vegetation by pasture areas. It was also observed that the Rn data was impacted by the dynamics of land use and occupation in the settlement, and was influenced by the availability of incident solar radiation on the days of 2017 and 2023. The areas of native vegetation showed the highest NDVI values with 0.91 on July 4, 2011 and Rn on September 6, 2017 with 754.85 Wm-² and October 25, 2023 with 797.33 Wm-², in addition to the lowest Ts values, while the areas of pasture and bare soil showed lower NDVI and Rn values, and higher Ts values in the years 2017 and 2023 with 28 and 37ºC. In relation to land use and cover in the PA, the 1996 pasture class had 6,639.527 hectares and in 2023 it increased to 20,024.18 ha, equivalent to a 332% increase in area. The biophysical parameters studied showed changes in the area of the Assurini settlement, with a decrease in its extension of 13,725.76 ha in 27 years after the creation of the PA and in 2023 there was a total loss of native forest of 52.20% in relation to 1996 and this reduction in forest areas was due to the conversion of these areas into spaces that develop activities related to agricultural expansion in the settlement. Therefore, the different land covers directly influenced the biophysical parameters and land use, which demonstrates different patterns of energy absorption behavior. It is therefore extremely important to consolidate public policies that are compatible with the reality of each settlement, as well as to create, disseminate and provide access to the means to introduce agricultural systems with more sustainable production.