Diameter caps for thinning southwestern ponderosa pine forests: Viewpoints, effects, and tradeoffs

Upper size limits of trees allowed to be cut, termed diameter caps, have resulted in polarization, litigation, and delays and alterations to thinning projects in many western forests. Using southwestern ponderosa pine forests as an example, we summarize viewpoints on caps, simulate effects of caps on thinning prescriptions, and provide examples of ecosystem-level tradeoffs of leaving extra trees during thinning projects. The importance placed on trees versus other ecosystem components primarily differentiates those who support caps and those who do not. We conclude that diameter caps may enhance some ecosystem components, such as densities of large trees, but they negatively impact many nontree components.