Sustaining Cavity-Using Species: Patterns of Cavity Use and Implications to Forest Management

Figure 2

Mean decay class of trees used by strong and weak primary cavity excavators and by secondary users in North America. Black bars represent conifers; grey bars are aspen; numbers in parentheses are sample sizes—the first number for conifers, the second for hardwoods. Decay classes of [16]. Data of [28, 55–66].