Converting Even-Aged Plantations to Uneven-Aged Stand Conditions: A Simulation Analysis of Silvicultural Regimes with Slash Pine (Pinus elliottii Engelm.)

There has been increasing interest in managing forest stands as uneven-aged structures to promote sustainable harvests as well as maintain ecosystem services. This study provides a framework for simulating conversion of mature even-aged stands to uneven-aged slash pine (Pinus elliottii Engelm.) stands using the USDA Forest Vegetation Simulator (FVS) model. A total of 73 scenarios, representing combinations of two harvest methods (based on either “BDq” and/or “low thinning”), two harvesting cycles (10 or 20 years), three harvest intensities (4.6 or 8.0 or 11.5 m 2 ha 1 residual basal areas), and six levels of regeneration (0 –2,224 seedlings ha 1 ) were evaluated for structural diversity, timber production, and carbon (C) stocks over a 100-year period. The BDq harvest approach, which applied selection cutting based on diameter regulation from the first cutting cycle onwards, resulted in higher structural diversity. Scenarios based on low thinning in the first cutting cycle and BDq method from the third cutting cycle onwards tended to result in higher total merchantable timber and C stocks over the entire simulation period, particularly at higher residual basal areas and longer cutting cycles. None of the scenarios maximized all of the three variables simultaneously. Based on the desired objectives, land managers can choose among scenarios presented. The study revealed that regeneration and establishment of as low as 247 seedlings ha 1 can lead to successful conversion and multiple benefits from uneven-aged slash pine stands.