Growth and yield models for forest stands on drained peatland sites in southern Finland

Linear regression functions are presented for predicting the volume increment and yield of peatland stands on sites drained far forestry in southern Finland. The data were collected from 329 permanent sample plots measured over a 70-yr period. Site was incorporated into the functions by means of four post-drainage classes (I-IV). These site classes were derived from the functional relationships between the post-drainage yield (total yield minus initial stand volume) at a reference time of 40 yr since drainage within the 21 vegetational site types represented in the data. The growth and yield functions were derived separately for each yield class. Stand volume, stem number, age since drainage, effective temperature sum, peat depth, and ditch spacing were used as predictors in the growth and yield functions. A site classification table, based on stand dominant height, drainage age, and initial volume, is presented for determining the yield class when applying the functions. Yield class can also be determined from the vegetational site types widely used in Finland. The reliability of the forecasts primarily depends on the quality of the data used in deriving the functions and on the input data in an application situation. Care should be taken when applying the functions to long-term simulations of future post-drainage growth and yield, where the growth and yield functions can be applied together. (C) 1998 Elsevier Science B.V.