Why is a rainforest like a city?

To address this question first think about what a city is. A city can be a community of different individuals. Grouped by ethnicity, age, social rank, etc. A city is shaped by those that live within those communities and what keeps the city moving. Now think about what happens within that city. L.A., New York, Boston whatever. The same is with a rain forest. A rain forest is a community of different species that live in one big city.