Existing floor area

An important variable for the management of forest resources

The stand base area G (also known as base area for short and in the past often called circular area) is an important factor in forestry yield science. It is a parameter that is used to assess the standing wood stocks in a forest and an important part of all forest inventories. It results from adding up the areas of all individual trees per hectare and is specified in. ${\ displaystyle {\ tfrac {m ^ {2}} {ha}}}$

Base area formula ${\ displaystyle G = \ sum _ {k = 1} ^ {N} g_ {i}}$

The base area is a measure of the density of the stand and is better suited than z. B. the number of trunks when deciding the strength of the thinning . It can be determined by taking a full picture or by random sampling using the angle count sample .

${\ displaystyle g}$ is the circular area of the individual trees and corresponds to the area of the trunk cross-section at breast height (breast height diameter BHD = 1.30 m).

Circle area formula: ${\ displaystyle g = \ left ({\ frac {\ pi} {4}} \ right) \ times BHD ^ {2}}$

Maintenance of floor space

ASSMANN (1961) writes in his book Forest Yield Science about the maintenance of the ground area and categorizes it according to the density of the stand.

He differentiates between:

Maximum base area (100% base area): Base area on which the highest possible number of trees grow. Natural stocking degree of a stand. (Unmanaged and undisturbed stock)
Optimal base area : Base area where the maximum increase is achieved. (100% increase)
Critical base area: Base area where only 95% of the increase is achieved.

Floor area development

The floor area in a managed stand varies depending on the strength of the maintenance measures. During the crawl, ? is reduced and this has effects on, among others:

the crown : The crowns expand and spread. There is an increase in the crown area.
Diameter / Height : Reducing G promotes diameter growth. The trees increase in thickness as well as in height (but much less than in diameter) and the deforestation of the trunks increases.
Volume / biomass : There is also an increase in volume (growth acceleration) and biomass.

All of these effects include: a. depending on the tree species, the stand age, the type of thinning and creditworthiness (performance of the location).

application

With the help of the base area G , the average stand height h and the shape number f (deforestation compensation value), the wood supply (wood volume in Vfm / ha) of a stand is calculated and the harvest quantity is estimated.

Formula:

${\ displaystyle wood supply = h \ times G \ times f}$

literature

German Association of Forest Research Institutes - Yield Science Section. Annual conference 21. – 23. May 2012, ISSN 1432-2609
Horst Kramer , Alparslan Akça: Guide to forest measurement . 3rd, expanded edition. Sauerländer, Frankfurt am Main 1995, ISBN 3-7939-0830-5 .
E. Assmann: Forest yield theory. BLV, Munich-Bonn-Vienna 1961, p. 490.
Forest management and forest growth ETH Zurich online