Site index curves for European aspen (Populus tremula L.) growing on forest land of different soils in Sweden.

Growth data were collected from from 40 European aspen (Populus tremula L.) stands growing on eight localities in Sweden. The stands ranged in latitude from 56 to 66°N. The mean age of the stands was 32 years (range, 12–63), the mean stand density 1978 stems ha–1 (range, 300–6000), and the mean diameter at breast height (on bark) 17 cm (range, 8–34). Site index curves were constructed for total age. Curves for H40 (dominant height at 40 years total age) were made for total Sweden. Curves fitted for H40 total age have another shape than curves presented by other Nordic studies. The curves from the present study have slower growth for young aspens than curves from norwegian and finnish conditions. For 50–70-year-old aspen stands, curves from the present study indicate taller heights than from Nordic studies. Classified soil types from the stands were grouped into three groups: sandy till (17), light clay (15) and medium clay till (4). As there was only one stand growing in the fine sand group and one stand in the heavy clay till group and two stands in the silty till group, these stands were not presented with growth curves. There were no statistically significant differences in site index between the three soil type groups. Some recommendations for management of aspen stand are given. Damages caused by moose, fungis and other injuries are discussed as a problem for height yield production and a good timber quality