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Single tree approaches are commonly seen as the primary alternative in the modelling of continuous cover forests. In some cases, however, the original inventory data may not allow their usage, at least not directly. Diameter distribution approach offers an intermediate solution, since it can be predicted with average stand parameters and allows the usage of single tree modelling based on size classes. The main aim of this paper is to improve and demonstrate the ability of diameter distribution approach to describe structurally diverse stands.

In practical applications the diameter distribution is usually predicted from the mean stand characteristics. The original variation observed in the stands obviously diminishes. This study indicates that by appropriately calibrating the predicted distribution with additional stand parameters irregular distributions can be obtained. Results are based on the data of sample plots located in unman aged stands of the boreal vegetation zone in Finland and Western Russia.

Diameter distributions were firstly predicted by using generally applicable parameter models for the Weibull function and percentile method. Secondly, calibration estimation was used to obtain a perfect estimate for each additional variable available from the stand. A number of auxiliary variables and their combinations were tested. A calibration estimator modifies the predicted frequencies of each diameter class by minimizing some distance measure subject to the calibration equations. ns.

Additional information

Authors: PUUMALAINEN J, EC-JRC, Environment and GEOinformation Unit, Ispra (IT);MALTAMO M, University of Joensuu, Faculty of Forestry (FI);KANGAS A, Finnish Forest Research Institute, Kannus Research Station (FI)
Bibliographic Reference: An oral report given at: Continuous Cover Forestry: Assessment, Analysis, Scenarios. Organised by:University of Gottengen. Held in: Gottengen (DE), 19-21 September 2001
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