Which statement describes PAI growth measurement?

• A. It measures annual maximum growth
• B. It measures growth over a fixed interval such as 10 years
• C. It measures mature height
• D. It measures only trunk diameter growth

Answer: (B)

Periodic annual increment is about the amount of growth that occurs over a defined time span, not a single year's instantaneous gain. It captures how much the stand has increased during a fixed interval (for example, 10 years) and is often expressed as the total gain over that period or as an average per year by dividing by the interval length. This fixed-interval approach makes it easy to compare productivity across stands or species with different ages, since you’re looking at a common time window. It isn’t about the maximum growth in one year, it isn’t limited to mature height, and while diameter growth can contribute to the measured increase (especially if using volume as the metric), PAI itself is defined by growth over the chosen interval, not just a single trait.