Relative Density as a Standardizing Metric for the Development of Size-Density Management Charts

Stand density management is central to achieving diverse silvicultural objectives. Decision-support tools in this domain range from expert opinion to sophisticated computer models that vary by forest type, region, and organization. The graphical frameworks represented by density management diagrams (DMDs) and stocking guides (SGs), collectively called size-density management charts (SDMCs), are well established and balance quantitative rigor with user accessibility. Regional differences in species composition and site quality are known to influence maximum size-density relationships, historically limiting the development of reliable charts. Advances in statistical modeling and data availability are overcoming this issue and should encourage more widespread use. We briefly review the history of SDMCs and propose the adoption of relative density based on stand density index as a logical metric for linking the DMD and SG formats. Examples of SDMC construction and use are illustrated for spruce-fir stands in Maine, USA.