how disruptions (natural or human-made) to any physical or biological component of an ecosystem can lead to shifts in all its populations.

Changes in either the physical or biological components can alter the populations of many different organisms. These changes are called disturbances and can be either natural (volcanic eruption, drought) or man-made (increase in nutrient input by adding fertilizers, extinction of a species by habitat removal).

Changes in either the physical or biological components can alter the populations of many different organisms. These changes are called disturbances and can be either natural (volcanic eruption, drought) or man-made (increase in nutrient input by adding fertilizers, extinction of a species by habitat removal).