What is current annual increment (CAI)?

• A. The average increase in tree size over five years.
• B. The annual height growth of the tallest tree.
• C. The increase in tree size for one year.
• D. The total height at maturity.

Answer: (C)

Current annual increment measures the growth that happens within a single year. It’s the amount a tree has increased in size during the current year, whether in height or diameter, from one year's measurement to the next. For example, if a tree’s height goes from 5.00 m to 5.25 m in a year, its CAI for height is 0.25 m; similarly, if DBH increases from 10.2 cm to 10.6 cm, the CAI is 0.4 cm for that year. This is different from the height at maturity or the total height reached overall, and it’s different from a mean annual increment, which averages growth over several years. The one-year change is precisely what CAI captures.