Forest managers seeking to meet biodiversity or restoration objectives while maintaining a flow of income may be disadvantaged in emerging forest carbon offset markets. Current protocols such as the Chicago Climate Exchange create incentives to accumulate short-term forest carbon stocks without regard for long-term specie composition or age class distribution in relation to a natural range of variability. While other protocols such as the Voluntary Carbon Standard (VCS) may benefit landowners to meet multiple objectives, such as those trying to balance financial objectives with restoration for biodiversity and long-term forest resilience to climate change.  Tools are needed to understand the implications of these carbon offset protocols for managed forests.

Forest managers managing for biodiversity or restoration objectives will often use an area regulation approach to determine harvest levels.  Determining annual harvest levels based on an area regulation approach facilitates the creation of a desired future condition; rather than employing a control method where the objective is a yearly harvest of approximately equal volume. We developed a carbon calculator to assess the carbon market eligibility under the VCS of restoration forestry activities being planned by Minnesota’s Aitkin and Cass County Land Departments.

This project evaluated the implications of this carbon calculator approach for determining eligible carbon for two public land managers in north central Minnesota that use the area regulation method (~500,000 acres total).  It used the carbon sub-model of the USFS Forest Vegetation Simulator (Lake States variant) to evaluate changes in forest carbon stocks under three different management scenarios (high, med, and low).  The carbon calculator allows the manager to determine the most effective way to manage carbon stocks while meeting other objectives. The calculator was then used to test the implications of shifting to lower intensity harvest practices that retain higher residual basal areas.  The planned distribution of harvests by cover type and intensity class using each manager's short-range tactical plans was considered Business as Usual (BAU) for use in the calculation of eligible carbon. 

Results/Conclusions

Using the carbon calculator, both counties were able to demonstrate eligible carbon volumes annually while employing the area regulation method.  A reduction in harvest intensity and a slight decrease in overall acreage harvested were able to provide higher post-harvest retention rates versus the BAU scenario.  The advantage of the area regulation strategy is that harvest acreage levels are predictable while carbon credits and associated biodiversity and restoration benefits are achieved.