The above spreadsheet will plot a Gingrich Stocking Diagram (Gingrich, 1967). Both diagrams for the range of 7 to 22 inches quadratic mean diameter(QMD) and 2 to 7 inches QMD are available. Additionally, the tab labeled "Stand Data" allow the user to plot their data on the diagram.
The Gingrich Diagram was present in in 1964 in a conference proceedings and again in 1967 in Forest Science. This diagram illustrates the relationship between basal area per acre, density (trees per acres) and the quadratic mean diameter (the diameter of the tree of average basal area). The A-line is the minimum tree area line and is based on the fully stocked stand that have never been thinned. Much of this data came from Schurr's publication on Volume and Yield of upland oaks accross the Central States region of the USA. Growth in stands above 100% are considered to slow for normal forest management. The B-line is the maximum tree area line as is the point of full site occupancity with trees of maximum tree area. A stand on the B-line is thought to have trees with no competition, yet no space wasted. The C-line is an estimate based on normal yield table of the lowest stocking that will grow to the B-line within ten years.
Gingrich, S. F. 1967. Measuring and evaluating stocking and stand density in Upland Hardwood forests in the Central States. For. Sci. 13:38-53.
Kershaw, Jr, J. A. and B. C. Fischer. 1991. Maximum size-density relationships for sawtimber-sized mixed upland central hardwoods. In: "The 8th Annual Central Hardwoods Conference", L. H. McCormick and K. W. Gottschalk eds. USDA, Forest Service, Northeastern Forest Experiment Station, General Technical Report, NE-148, pp. 414-428.
Krajicek, J. E. and K. A. Brinkman and S. F. Gingrich. 1961. Crown competition-a measure of density, For. Sci. 7:35-42.
