Final answer:
Secondary succession is faster because soil is already present, full of nutrients, and remnants of the previous biological community can speed up the process, unlike in primary succession where soil and community must develop from nothing.
Step-by-step explanation:
The reason why secondary succession occurs faster than primary succession is primarily that in secondary succession, the soil is already present and typically full of nutrients. This nutritious soil helps pioneer species, like grasses, to quickly establish themselves and begin the process of succession. In contrast, primary succession begins on newly exposed or formed land such as after a volcanic eruption, where soil must be created from scratch through the slow process of weathering and accumulation of organic material from pioneer species, such as lichens and hardy plants. Secondary succession also benefits from the remnants of the previous community, which can include seeds, roots, and microorganisms that facilitate the regrowth of vegetation.