Managing Hardwood-Softwood Mixtures for Future Forests in Eastern North America: Assessing Suitability to Projected Climate Change
Despite growing interest in management strategies for climate change adaptation, there are few methods for assessing the ability of stands to endure or adapt to projected future climates. We developed a means for assigning climate "Compatibility" and "Adaptability" scores to stands for assessing the suitability of tree species for projected climate scenarios. We used these scores to determine whether mixed hardwood-softwood stands or "mixedwoods" were better suited to projected future climates than pure hardwood or pure softwood stands. We also examined the quantity of aboveground carbon (C) sequestered in the overstory of these mixtures. In the four different mixedwood types that we examined, we found that Pinus echinata-Quercus mixtures in the Ozark Highlands had greater Compatibility scores than hardwood stands and greater Adaptability scores than pure Pinus echinata stands; however, these mixtures did not store more aboveground overstory C than pure stands. For Pinus strobus-Quercus rubra, Picea-Abies-hardwood, and Tsuga canadensis-hardwood mixtures, scores indicated that there were no advantages or disadvantages related to climate compatibility. Those mixtures generally had greater Adaptability scores than their pure softwood analogs but stored less aboveground overstory C. Despite the many benefits of maintaining mixedwoods, regenerating and/or recruiting the softwood component of these mixtures remains a persistent silvicultural challenge.