Final answer:
Ecosystems change due to disturbances from natural events or human activities. Succession is the process of ecological recovery, where new communities of plants and animals replace the ones affected. Human actions like deforestation and overfishing can also cause significant ecosystem changes.
Step-by-step explanation:
Ecosystems change when they are subjected to various disturbances, either from natural forces or human actions. Succession is a critical concept in ecology, referring to the natural process by which ecosystems recover from disturbances. After a disturbance, like a forest fire caused by lightning, the land typically goes through a series of changes in vegetation, starting with grasses, then shrubs and bushes, and eventually mature trees. This ecological succession is a form of ecosystem recovery.
However, human actions such as deforestation, pollution, and overfishing also significantly impact ecosystems, sometimes leading to drastic and rapid changes. Farming, for example, can lead to the clearing of natural habitats, while overfishing can deplete species and alter aquatic ecosystems.
Changes in an ecosystem can occur in various time frames; from short-term changes like unseasonal rainfall or seasonal patterns to long-term changes such as melting glaciers and the rise in water levels that may submerge islands and change local ecosystems drastically.