Mrs. Zammit introduces the second geography topic on ecosystems, covering the basic components, including living and non-living factors, and the roles of producers, consumers, and decomposers. She explains that ecosystems are communities of organisms interacting with their environments, with stability often linked to diversity, though they can be disrupted by natural events like earthquakes or fires. The lesson includes definitions and examples of ecosystem structures, such as individual species, populations, communities, biomes, and the biosphere, illustrated by a pond ecosystem.