Stand density management diagram
Encyclopedia
A stand density management diagram is a simple biological model
relating forest yield to forest density at any stage of a particular forest
stand's development. Stand density management diagram
s are used in forest management
and designed to use a current stand's density
to project its future yield
. 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 published his idea of comparing basal area
per acre
, trees per acre, and quadratic mean diameter
in one graph
. He called this the stocking diagram. These same principles are used to make the stand density management diagram work. Basal area
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
of the volume
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.
Mathematical model
A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used not only in the natural sciences and engineering disciplines A mathematical model is a...
relating forest yield to forest density at any stage of a particular forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
stand's development. Stand density management diagram
Diagram
A diagram is a two-dimensional geometric symbolic representation of information according to some visualization technique. Sometimes, the technique uses a three-dimensional visualization which is then projected onto the two-dimensional surface...
s are used in forest management
Forest management
200px|thumb|right|[[Sustainable development|Sustainable]] forest management carried out by [[Complejo Forestal y Maderero Panguipulli|Complejo Panguipulli]] has contributed to the preservation of the forested landscape around [[Neltume]], a sawmill town in Chile...
and designed to use a current stand's density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
to project its future yield
Crop yield
In agriculture, crop yield is not only a measure of the yield of cereal per unit area of land under cultivation, yield is also the seed generation of the plant itself...
. 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 published his idea of comparing basal area
Basal area
Basal area is the term used in forest management that defines the cross-sectional area of a tree at DBH, inside the bark.In most countries, this is usually a measurement taken at a specimen's breast height above the ground and includes the entire diameter of every tree, including the bark...
per acre
Acre
The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. The most common use of the acre is to measure tracts of land.The acre is related...
, trees per acre, and quadratic mean diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
in one graph
Information graphics
Information graphics or infographics are graphic visual representations of information, data or knowledge. These graphics present complex information quickly and clearly, such as in signs, maps, journalism, technical writing, and education...
. He called this the stocking diagram. These same principles are used to make the stand density management diagram work. Basal area
Basal area
Basal area is the term used in forest management that defines the cross-sectional area of a tree at DBH, inside the bark.In most countries, this is usually a measurement taken at a specimen's breast height above the ground and includes the entire diameter of every tree, including the bark...
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
Logarithm
The logarithm of a number is the exponent by which another fixed value, the base, has to be raised to produce that number. For example, the logarithm of 1000 to base 10 is 3, because 1000 is 10 to the power 3: More generally, if x = by, then y is the logarithm of x to base b, and is written...
of the volume
Volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....
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.