Bare rock is exposed

3. After many years, there is enough soil  Lichens are replaced by mosses  Insects & other tiny organisms begin to live here. Bare rock is exposed Soil deepens  Mosses are replaced by ferns Ferns are replaced by grasses & wildflowers Small trees may grow if there is enough soil & shrubs Lichens form  Their acids break down rock into particles  These particles mix with other dead lichens to form soil. klk Hundreds to thousands of years pass  Soil can be deep and stable enough to support a forest.

7. New weeds such as horseweed appears due to seeds being spread by wind or small insects. Weeds such as crabgrass begins to grow first. Disturbance or natural disaster occurs causing severe damage to the area. In this case, it is a fire. In approximately 5 to 15 years, small conifer trees may start growing among the weeds. The trees continue to grow. In about 100 years, a forest may form As older conifers die, they may be replaced by hardwoods, such as oak or maple trees if the environment can support them.

9. Hardwoods (Oak or Maple) Crabgrass Conifer Trees Horseweed