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Stand Density Index
Stand density index (SDI; also known as Reineke's Stand Density Index after its founder) is a measure of the stocking of a stand of trees based on the number of trees per unit area and diameter at breast height (DBH) of the tree of average basal area, also known as the quadratic mean diameter. It may also be defined as the degree of crowding within stocked areas, using various growing space ratios based on crown length or diameter, tree height or diameter, and spacing. Stand density index is usually well correlated with stand volume and growth, and several variable-density yield tables have been created using it. Basal area, however, is usually satisfactory as a measure of stand density index and because it is easier to calculate it is usually preferred over SDI. Stand density index is also the basis for Stand density management diagrams. Use It may also be defined as the degree of crowding within stocked areas, using various growing space ratios based on crown length or diameter, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stocking (forestry)
In forestry, stocking is the measure of the extent to which the growth area potential is used by trees or other vegetation. Stocking is a quantitative measure of the area occupied by trees, usually measured in terms of well-spaced trees or basal area per hectare, relative to an optimum or desired level of density. It is also known as a measure of the growth potential of a site that may be affected by vegetation in the area along with other nearby trees. Stocking can be shown as a ratio of the current stand density to the stand density of a maximally-occupied site. Stocking measures account for three things: the cover type and species mixture in the stand, the basal area per acre, and the number of trees per acre. Stocking allows for the comparison of stands that may have diverse ecology. Stocking is a major part of forest management and how to control the growth of trees in certain areas. They have developed more approaches that account for different ages of stands and grow areas. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diameter At Breast Height
Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements. Tree trunks are measured at the height of an adult's breast, which is defined differently in different countries and situations. In many countries, DBH is measured at approximately above ground. Global variation and scientific precision The height can make a substantial difference to the measured diameter. In the United States, DBH is typically measured at above ground. In some countries, such as Australia, New Zealand, Burma, India, Malaysia, and South Africa, breast height diameter has historically been measured at a height of , but because of much active research into allometrics that are being applied to trees and forests, the convention of is more appropriate. Ornamental trees are usually measured at 1.5 metres above ground. Some authors have argued that the term DBH should be aboli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 or per acre basis. If you cut down all the merchantable trees on an acre at 4 ½ feet off the ground and measured the square inches on the top of each stump (πr*r), added them all together and divided by square feet (144 sq inches per square foot), that would be the basal area on that acre. In forest ecology, basal area is used as a relatively easily-measured surrogate of total forest biomass and structural complexity, and change in basal area over time is an important indicator of forest recovery during succession . Estimation from diameter at breast height The basal area (BA) of a tree can be estimated from its diameter at breast height (DBH), the diameter of the trunk as measured 1.3m (4.5 ft) above the ground. DBH is conver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadratic Mean Diameter
In forestry, quadratic mean diameter or QMD is a measure of central tendency which is considered more appropriate than arithmetic mean for characterizing the group of trees which have been measured. For ''n'' trees, QMD is calculated using the quadratic mean formula: \sqrt where is the diameter at breast height of the ''ith'' tree. Compared to the arithmetic mean, QMD assigns greater weight to larger trees – QMD is always greater than or equal to arithmetic mean for a given set of trees. QMD can be used in timber cruises to estimate the standing volume of timber in a forest, because it has the practical advantage of being directly related to 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 hectar ..., which in turn is directly related to volume. QMD can also be calculated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stand Density Management Diagram
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.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 diagrams 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lodgepole Pine
''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpine, but is rare in lowland rain forests. Like all pines (member species of the genus ''Pinus''), it is an evergreen conifer. Description Depending on subspecies, ''Pinus contorta'' grows as an evergreen shrub or tree. The shrub form is krummholz and is approximately high. The thin and narrow-crowned tree can grow high and achieve up to in diameter at chest height. The ''murrayana'' subspecies is the tallest. The crown is rounded and the top of the tree is flattened. In dense forests, the tree has a slim, conical crown. The formation of twin trees is common in some populations in British Columbia. The elastic branches stand upright or overhang and are difficult to break. The branches are covered with short shoots that are easy to remove. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bark Beetle
A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the term "bark beetle" refers to the fact that many species feed in the inner bark (phloem) layer of trees, the subfamily also has many species with other lifestyles, including some that bore into wood, feed in fruit and seeds, or tunnel into herbaceous plants. Well-known species are members of the type genus ''Scolytus'', namely the European elm bark beetle ''S. multistriatus'' and the large elm bark beetle ''S. scolytus'', which like the American elm bark beetle ''Hylurgopinus rufipes'', transmit Dutch elm disease fungi (''Ophiostoma''). The mountain pine beetle ''Dendroctonus ponderosae'', southern pine beetle ''Dendroctonus frontalis'', and their near relatives are major pests of conifer forests in North America. A similarly aggressive spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Site Index
Site index is a term used in forestry to describe the potential for forest trees to grow at a particular location or "site". Site is defined as "The average age of dominate and/or codominate trees of an even-aged, undisturbed site of intolerant trees at a base age"; furthermore, the word site is used in forestry to refer to a distinct area where trees are found. Site index is used to measure the productivity of the site and the management options for that site and reports the height of dominant and co-dominant trees in a stand at a base age such as 25, 50 and 100 years. For example, a red oak with an age of 50 years and a height of will have a site index of 70. Site index is species specific. Common methods used to determine site index are based on tree height, plant composition and the use of soil maps. Determining site index The most common of the methods used to determine site index is tree height. Determining site index is achieved by measuring and averaging the total height ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
