Biogeochemical Cycles

The atoms currently constructing the cells of your hand have been recycled billions of times since the Earth cooled. A single carbon atom in your DNA might have once been locked in the shell of a marine diatom, released by a volcanic eruption, or woven into the leaf of a prehistoric fern. This continuous, ancient relay race is governed by a strict physical law: matter in an ecosystem is continuously conserved and recycled.

This stands in stark contrast to the flow of energy. While atoms are infinitely reusable, energy flows through an ecosystem in a single direction and is eventually lost as heat. This fundamental asymmetry—energy flows, matter cycles—is the core engine of ecology and the foundation upon which all biological systems are built.