Stand Growth - Classical Method ©

The STANDARD or CLASSICAL METHOD of deriving increment data for stands in which the trees are not identified is described on p.150 of Carron (1968) . This method was modified by Smithers (1949) . Smithers' modification is so much easier to understand and apply that the standard method is now seldom used. Some years earlier, Prodan (1947) proposed an alternative method of deriving the increment in which the increments of the coming and past periods are derived separately in the one analysis. Carron (op. cit., p. 156)) compared actual increments with increments derived by both the Standard Method and Prodan's Method. He found that the latter gave remarkably good estimates of increment and was superior to the Standard Method and thus to Smither's Modification of it.

All these methods of deriving increment assume:

  1. trees are evenly distributed throughout a diameter class
  2. trees in a class grow at the same rate.
Both assumptions are seldom fulfilled. The agreement between the calculated increment and the actual increment will depend on the extent to which the assumptions are fulfilled.

Because it is normal in periodic measurement to nominate a lower limit to dbhob measurement, ingrowth will occur between inventories and there may also be some mortality and thinning/harvesting (yield). Each of these must be taken into account in calculating the increment. This is done by a sensible adjustment of the stand tables prior to calculating the increment.

These methods are now seldom applied in Australia, we shall not deal with them further. Note, however, that they are still applied in some tropical countries where identifying individual trees is impractical. 

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Document URLhttp://online.anu.edu.au/Forestry/mensuration/CLAS_GRO.HTM
Editor Cris Brack ©
Last Modified DateFri, 9 Feb 1996