Spatial and temporal effects of urban growth in Manaus: examining urban and periurban sprawl in the heart of the world's largest tropical rainforest, Brazil

Urban and periurban sprawl is a complex and active spatial-temporal process affected by population dynamics, land use, economic factors, and government policies. It has intensified over time, especially in developing countries. Driven by population growth, urban expansion can pressure areas of native vegetation close to cities. As a result, these changes contribute to landscape change, site degradation, and losses in ecosystem services. In addition, unplanned urban and periurban sprawl tends to occur over areas of adjacent forest cover and agricultural lands. This research aims to demonstrate the driving forces and causes of land use change and to assess the impacts of change on humans and the environment in Manaus, the most populous city in the Amazon rainforest. We performed the intensity of land use change in a 36-year historical series provided by the MapBiomas Project - Collection 7 from 1985 to 2021. The intensity analysis details the changes in three levels: Interval, category, and transition, using the OpenLand package in R statistical language. Our results show that the proportion of forest areas has decreased from 68.95% in 1995 to 66.75% in 2021, and farming areas have decreased from 11.08% in 1995 to 9.91% in 2021. In contrast, the proportion of urban areas has increased from 3.71% in 1985 to 10.16% in 2021, and the proportion of mining areas has increased from 0.06% in 1995 to 0.33% in 2021. We highlight the changing priorities and pressures on the environment in the city of Manaus, with increased urbanization and resource extraction at the expense of natural environments and the fluctuation in the rate of change over time, with fast-paced changes occurring more frequently between 1985 and 2000, followed by a shift towards slow-paced changes from 2005 to 2021.