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# Relationship between Current Annual Increment & Mean Annual Increment

## Relationship between Current Annual Increment & Mean Annual Increment

Every year the volume of a tree increases by a quantity known as current Annual Increment. It is very difficult to measure the increment every year. For this reason, it is measured after 5 or 10 years and then its mean is called CAI.
For example, the increase in the volume of a tree is 10 cft. In 5 years its CAI will be 10/5=2 cft.
The CAI of a tree starts slowly during initial stages and accelerates with the increase in age till it reaches its highest point and then starts declining rapidly.

Besides age CAI is also affected by environment.

Mean Annual Increment (MAI) when the volume of a tree is divided by its age we get its mean annual increment.
When MAI for any species is plotted against its age, a smooth curve results which rise steadily and reaches its highest point. Then it gradually declines but does not drop to zero.
When CAI and MAI Curves are drawn, CAI initially remains above MAI and reaches a peak earlier than MAI. The point at which CAI and MAI end each other is called Economic Rotation of the species.

 Years VOl cft MAI cft DAI cft 1 2 2 2 2 4 2 2 3 7 2.3 3 4 10 2.25 3 5 14 2.8 4

(The graph given below is not in accordance with the table. It simply shows the CAI, MAI, and Economic Rotation)
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