A stand density management diagram is a simple biological model relating forest yield to forest density at any stage of a particular

forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

stand's development.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. Stand density management

diagram A diagram is a symbolic representation of information using visualization techniques. Diagrams have been used since prehistoric times on walls of caves, but became more prevalent during the Enlightenment. Sometimes, the technique uses a three ...

s are used in

forest management Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, protection, and forest regulation. This includes management fo ...

and designed to use a current stand's

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...

to project its future yield.British Columbia Ministry of Forestry. How to use a stand density management diagram. Published 1997. Accessed 17 March 2008.
/ref> 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 have transformed ideas long held in traditional stocking diagrams. In 1967,

Samuel F. Gingrich Samuel ''Šəmūʾēl'', Tiberian: ''Šămūʾēl''; ar, شموئيل or صموئيل '; el, Σαμουήλ ''Samouḗl''; la, Samūēl is a figure who, in the narratives of the Hebrew Bible, plays a key role in the transition from the bibl ...

published his idea of comparing

basal area Basal area is the cross-sectional area of trees at breast height (1.3m or 4.5 ft above ground). It is a common way to describe stand density. In forest management, basal area usually refers to merchantable timber and is given on a per hectare ...

per

acre The acre is a unit of land area used in the imperial and US customary systems. It is traditionally defined as the area of one chain by one furlong (66 by 660 feet), which is exactly equal to 10 square chains, of a square mile, 4,840 square ...

, trees per acre, and

quadratic mean In mathematics and its applications, the root mean square of a set of numbers x_i (abbreviated as RMS, or rms and denoted in formulas as either x_\mathrm or \mathrm_x) is defined as the square root of the mean square (the arithmetic mean of th ...

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...

in one

graph Graph may refer to: Mathematics *Graph (discrete mathematics), a structure made of vertices and edges **Graph theory, the study of such graphs and their properties *Graph (topology), a topological space resembling a graph in the sense of discre ...

. He called this the

stocking diagram Stockings (also known as hose, especially in a historical context) are close-fitting, variously elastic garments covering the leg from the foot up to the knee or possibly part or all of the thigh. Stockings vary in color, design, and transparen ...

. These same principles are used to make the stand density management diagram work.Fischer

Basal area Basal area is the cross-sectional area of trees at breast height (1.3m or 4.5 ft above ground). It is a common way to describe stand density. In forest management, basal area usually refers to merchantable timber and is given on a per hectare ...

and density are plotted against one another and quadratic mean diameter lines are plotted through the plot. The diagram itself is a plot of the natural

logarithm In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a number to the base is the exponent to which must be raised, to produce . For example, since , the ''logarithm base'' 10 of ...

of the

volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). Th ...

or yield against the natural logarithm of 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. The diagram works well for even aged, single cohort stands. However, it is not as effective with uneven-aged stands.

References

{{Forestry Forest modelling

See also

References