Harri Vasander

Otanta vähäpuustoisten rämeiden biomassa- ja tuotostutkimuksissa

Vasander H. Otanta vähäpuustoisten rämeiden biomassa- ja tuotostutkimuksissa.

Tiivistelmä

The above-ground biomass and production of two pine stands in the bog Laaviosuo Lammi, Southern Finland, were determined (c.f. Lindholm & Vasander 1979; Fig. 5). One stand was in the virgin ombrotrophic kermi pine bog (KeR, o.b. volume of the stand 1.7 m3/ha) and the other in the drained and fertilized part of the bog (KeRmu, o.b. volume 12.1 m3/ha). Biomass and production values considered to be absolute were obtained by the total tally of the stands. This was done by studying an average of three sample trees in every size class measured by the DBH (1.3 m) with the interval of 1 cm and summing these values. The following average tree methods were compared to these results: 1) tree of mean DBH, 2) tree of mean basal area, 3) tree of mean volume, 4) median tree, 5) median tree by basal area, 6) in KeRmu where three tree classes could be distinguished, sample trees were taken in every tree class (DBHs 2,7 and 13 cm), 7) in KeR where the tree histogram was continuous (see Lindholm & Vasander 1979; Fig. 5), several sets of two or three tree classes were tried: 7a) 2,6 cm, 7b) 2,7 cm, 7c) 3,6 cm, 7d) 3,8 cm, 7e) 2, 6, 10 cm (the numbers of the methods are the same as in Figs. 1, 2). Usually the average tree approach gave crude results compared to those of the total tally. In KeRmu the tree of the mean volume was the most accurate of the individual average tree methods (c.f. Ovington & Madgwick 1959, Baskerwille 1965). Here this method overestimated the total biomass by 5.9 % and the total production by 7.9 %. Regarding the different tree components the errors obtained were greater as were also the total values in KeR where method 2 gave a little more accurate results (Figs. 1, 2). If the stand was stratified into three tree layers in KeRmu, almost similar total biomass and production values were obtained as the total tally (Fig. 2, method 6). In KeR total values with the accuracy of appr. ± 10 % were obtained with two tree classes. The other tree class had to be selected amongst those small trees which formed the majority of the tree histogram (DBHs 2 or 3 cm) and the other amongst the trees in the middle of the histogram (DBHs 6, 7 or 8 cm). The values of the individual tree components were in this case, however, more inaccurate than the total values (Fig. 1).

Vastaanotettu 31.10.2017 Julkaistu 1.1.1982

Katselukerrat 471

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