Comparison of fixed diameter-limit and selection cutting in northern conifers

Diameter-limit cutting is a common type of harvest in which all merchantable trees above specific size thresholds are removed. Despite a long history of application, controlled experiments of these harvests are rare and the cumulative effects of repeated diameter-limit cuts are largely unknown. The Penobscot Experimental Forest in Maine is the location of a long-term USDA Forest Service experiment in which both fixed diameter-limit and selection cutting have been applied at 20-year intervals since the early 1950s. After three entries, present value of gross harvest revenue was greater in the fixed diameter-limit than selection treatments. However, sawtimber volume and growth, total and merchantable volume, regeneration stem density, and inventory value all were lower in the fixed diameter-limit than selection stands. Accumulated value (harvest plus residual) and species composition did not differ between treatments. Within-treatment analysis revealed desirable directional changes in cull percentage and species composition in the selection but not diameter-limit cut stands, suggesting trends that may result in greater future treatment disparity. These data confirm the degrading effects of fixed diameter-limit relative to selection cutting, and reveal that greater short-term value removals are offset by lower residual stand volume and value.