Although within terrestrial ecosystems, we must point out a particular ecosystem, cities and their urban ecosystem. In the human environment, with its buildings, streets, cars, pollution, etc., there are characteristics that have allowed some living beings to adapt to them. For example, the temperature of cities is a couple of degrees higher than their surroundings.
The level of producing organisms is almost nil, since most of the food has an external origin and the trophic levels of the consumers predominate. Only in some parks and green areas can there be fruits, for example, that feed the primary consumers.
Although the main consumer is humans, other species such as dogs, cats, live with it. And others, such as pigeons, sparrows, ants, etc., which are also primary consumers. There may even be a bird of prey in our cities. The cycle of matter is not completed, since waste accumulates in landfills and some are even difficult to recycle.
Patio of the IES Ramón Pignatelli (Zaragoza): Map with the main trees and shrubs in the patio.