Lifecycle of a forest
The graph represents the total amount of forest production. The lower graph represents the logging periods; By the age of 15 the size of the forest is reduced by nearly half. This is done by the cleaning the forest for seedling. After that the forest continues to grow to the age of 30. This is when the first thinning of the forest is done. Another 2 thinning processes are done afterwards. One is done at the age of 50 and the other at the age of 70. After this the forest grows to the age of 90. This is when the final felling is done.
As the picture shows, about half of the forest disappears during the thinning processes.