What is a characteristic of an ecosystem at equilibrium?

A characteristic of an ecosystem at equilibrium is stable interactions among species. When an ecosystem is in equilibrium, the populations of various species maintain relatively constant sizes, and interactions such as predation, competition, and symbiosis achieve a balance. This stability allows various species to coexist without significant fluctuations in their populations, leading to a harmonious ecosystem dynamic.

While constant change in species population can occur due to external factors or disturbances, it does not represent equilibrium. Rapid energy transfer is associated with certain energy-dense ecosystems, but it does not inherently indicate stability. High biodiversity is often found in healthy ecosystems, but not all stable ecosystems require high biodiversity; a stable ecosystem can also be comprised of fewer species that interact in balanced ways. Hence, stable interactions among species is the most accurate characteristic that depicts an ecosystem at equilibrium.