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Stand Density Management Diagram

Stand Density Management Diagram

The density management diagram is best described as a “simple biological model relating yield and density at any stage of stand development” (Kershaw and Fischer). Stand density management diagrams are designed to use current stand density to project what the future of the stand will look like (Ministry). One major reason for the effectiveness of density management diagrams is the relatively low effect of site variance on the diagram’s shape. Density management diagrams are a transformation of the traditional ideas held in stocking diagrams. Gingrich came up with the idea of comparing basal area per acre, trees per acre, and quadratic mean diameter in one graph. He called this the stocking diagram (Kershaw and Fischer). These same principles are used to make the stand density management diagram work (Fischer). Basal area and density are plotted against one another and quadratic mean diameter lines are plotted through the plot. The diagram itself is comprised of a plot of the natural log (ln) of the volume or yield against the density in stems per acre. Just like a stocking diagram, the A-line, B-line, and C-line are plotted. In addition, the -3/2 rule maximum density line is plotted just above the A-line (Kershaw and Fischer). The diagram works well for even aged, single cohort stands. However, it is not as effective with uneven aged stands (Ministry).

Works cited

Kershaw, J. A., and B.C. Fischer. 1991. A stand density management diagram for sawtimber sized mixed upland central hardwoods. pp. 414-428 in McComick, L.H. and Gottschalk, K.W., eds. Proceedings, 8th Central hardwood forest conference.

British Columbia Ministry of Forestry. How to use a stand density management diagram. Published 1997. Accessed 17 March 2008. <http://www.for.gov.bc.ca/hfp/publications/00169/SDMD_get.pdf>.