Final answer:
Ecological succession is the process by which a community changes over time. It can be either primary or secondary succession, depending on whether the area has been previously inhabited. Pioneer species colonize newly formed or disturbed areas and gradually transition to a climax community, which is a stable state. Ideas about succession and climax communities have evolved, and ecologists now understand that ecosystems are dynamic rather than reaching a final, stable state.
Step-by-step explanation:
Ecological succession is the process by which a community changes over time. There are two types of succession: primary succession and secondary succession. Primary succession occurs in an area that has never been colonized before, such as a newly formed land or bare rock. It begins with pioneer species that can tolerate harsh conditions, like lichens and mosses. These plants break down the substrate and create soil, allowing other species to colonize the area. As more species establish, the community gradually changes, and eventually reaches a stable state called a climax community.
Secondary succession, on the other hand, occurs in an area that was previously inhabited but disturbed, such as a forest fire or abandoned agricultural land. Unlike primary succession, soil already exists in secondary succession. Remnants of the previous community, like tree stumps or seeds in the soil, provide a starting point. The pioneer species in secondary succession are different from those in primary succession. They are often shade-tolerant plants, like grasses or shrubs. As the community develops, it transitions through a series of intermediate species, until reaching a climax community.
Ideas about ecological succession and climax communities have evolved over time. Early ecologists believed that succession always progresses in a predictable series of stages and ends with a climax community. However, modern ecologists recognize that ecosystems are dynamic and constantly changing. They understand that disturbances can reset succession and prevent the development of a climax community.