Why doesnt secondary succession simply start with the growth of trees?

Secondary succession doesn't start with the growth of trees because the initial conditions of the environment often require the establishment of pioneer species first. These are typically fast-growing plants, such as grasses and shrubs, that stabilize the soil and create a more favorable environment for later species, including trees. The presence of these initial species helps improve soil quality, retain moisture, and provide nutrients, ultimately allowing for the gradual establishment of a forest ecosystem. Thus, the process is a gradual progression rather than an immediate transition to tree growth.