Ecological engineering is the creation of a community of plants, animals, microbes, and technological components, so that they provide some service. An example of such an engineered ecosystem is an in-vessel composter, in which a community of microbes breaks down organic waste into a soil-like product and the vessel controls the microbes’ environment to keep them happy.

A different view of ecological engineering is the study of existing ecosystems to learn how material and energy flow through them. This understanding inspires the design of better technological systems. An example of such ecologically-inspired design is the construction of a building that is naturally ventilated, based on the principles of convective airflow observed in termite mounds.
 

Ecosystems are complex adaptive systems, meaning that they are made up of very many components that interact with one another and their surroundings in complicated and surprising ways. The dynamics of complex systems generate fascinating spatial and temporal patterns. Natural systems that are driven by energy gradients tend to become increasingly complex. All living things are complex systems. Ecosystems, for example, are made up of trillions of organisms that use gradients in light energy and chemical concentrations to grow.