Forest Resources Management Exam 1 Practice

Mean annual increment is the average amount added per year up to a given age. It’s defined as MAI = Y_a / a, where Y_a is the total yield at age a and a is the age in years. Here, Y_a is 240 at age 40, so MAI = 240 / 40 = 6 units per year. This means the stand has accumulated about 6 units of yield on average each year up to age 40. If you used a different age or yield, you’d get a different MAI, but with these values the result is 6 units/year.