Dynamics of land cover and land use in Pernambuco (Brazil): Spatio-temporal variability and temporal trends of biophysical parameters

Changes in land use and land cover can generate the degradation of ecosystems or can be linked to a recovery of their functions. In this sense, the study of biophysical parameters of the surface helps to identify patterns and quantify the changes that have occurred. The objective was to evaluate the changes in biophysical parameters in the state of Pernambuco during 2000-2019 of albedo, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Soil Adjusted Vegetation Index (SAVI), Normalized Difference Water Index (NDWI), and Surface Temperature (ST) with data from the MODIS sensor. The MOD09A1 and MOD11A1 image product collections estimate the biophysical parameters on the Google Earth Engine (GEE) software/platform. Reduced annual images of the parameters listed above were generated, totaling 120 images, in which we obtained the descriptive statistics of each one. For the climatic characterization of the study area, we extracted monthly pixel values in 45 rainfall stations and determined the annual averages of the biophysical parameters and annual accumulated rainfall. We applied the Mann-Kendall temporal trend test, the Kendall coefficient, and the Theil-Sen test to determine the significance, direction, and magnitude of changes in the biophysical parameters from 2000 to 2019 at regional (state) level and homogeneous rainfall zones. The results indicate that rainfall affected the behavior of the biophysical parameters, with a decrease in SAVI by 0.06 (-19%) and an increase in temperature by 2.70 degrees C, (+9%) when comparing rainy and dry years. Vegetation indices decreased, and surface temperature increased throughout the state, however, the results were not significant. At the level of homogeneous rainfall zones, only the coastal region showed a significant reduction in vegetation indices in the order of 0.04 in the analyzed period, demonstrating that economic and social pressures may be altering the dynamics of the local ecosystem. Other studies can compare different regions to verify the possible effects of different public policies on the preservation of natural resources.