Why are plants important in succession?

Question

Science homework.

Answer 1

I would also add that those pioneering species also tend to be nitrogen fixers, and create plant available nitrogen for later successional plants to use.

Answer 2

Assuming the geographic area is bare, no vegetation, pioneer plants suitable to the habitat will colonize the area.  Pioneers are often lichens, mosses and grasses.  The mosses and grasses can grow in small crevices helping to capture soil particles and forming humus from decaying plant materials.  Once some soil and humus accumulate other plants will become established and change the habitat.  As nutrients become available from the plants, populations of animals and decomposers.  Eventually a stable biome will become established until something distrubs it such as landslides, floods, fires, human activities and the like.