By definition, an ecosystem consists of a system that includes biotic (living organisms) and abiotic (non-living parts) factors working together as a unit.
In other words, it is an ecological community where the different populations of organisms coexist in a particular area called habitat.
There are natural ecosystems, these are found in nature where the organisms coexist with each other and the other components of the environment without any human intervention, for example, natural forests, grasslands, mountains.
Another type of ecosystem is called urban ecosystem. These ecosystems correspond to systems located in cities or other densely populated areas. In these ecosystems, the biotic factors and abiotic factors coexist just like on natural ecosystems with the difference that it includes the human population and its demographic characteristics, social, economic, and institutional structures, and all human interactions with the other factors of the environment.
Following these definitions, you can conclude that the city of Selma Alabama does have an ecosystem.