This succession may be defined as the change in the biological community of the species on the barren land. The pioneer species is lichen. This succession is slow and takes more time to develop into a climax community.
Secondary succession:
This succession may be defined as the succession on the land that has been destroyed by the natural or human calamity. The remains of the earlier plant or spores may acts as the pioneer species. This succession is fast and takes less time to develop into a climax community.
It's often impossible to repeat trials on the same subjects. 2-Subjects may report an inaccurate medical history. 3-It can be difficult to control all possible variables. 4-It's impossible to come up with testable scientific questions for human subjects.
