Site index curves for common alder and grey alder growing on different types of forest soil in Sweden

摘要

Growth data were collected from 32 stands of common alder (Alnus glutinosa) in southern Sweden and 26 stands of grey alder (Alnus incana) in southern and central Sweden. Most had been thinned once before the study, or if not they had been cleaned ata young age. For common and grey alder, respectively, the mean age of the stands was 48 yr (range 21-91) and 40 yr (range 21-66), the mean stand density 1174 stems ha-1 (range 440-2994) and 2140 stems ha-1 (range 591-5120), and the mean diameter at breast height (on bark) 21 cm (range 13-27 cm) and 17 cm (range 9-25 cm). Site index curves were constructed for total age. Curves for H40 (dominant height at 40 yr total age) were constructed using data from all the stands investigated. Curves fitted for H40 total age of common alder were found to have the same shape as curves developed for German conditions. Site index curves for grey alder showed higher growth for middle-aged trees than those shown by curves developed for Norwegian stands. Older Finnishsite index curves for grey alder were found to have the same shape as curves constructed in the present study in Sweden. Soil types in the common alder stands were divided into 4 groups: moorland peat/light clay (n = 5), moorland peat/sand (5), cambisol/sand (4) and fine sand (4). For grey alder stands the soils were divided into 3 groups: silt (4), sandy till (3) and cambisol/light clay (3). Soil types represented by only 1 or 2 stands were not included in the analysis. No statistically significant differences in site index were found between the 4 soil-type groups in common alder stands or between the 3 soil-type groups in grey alder stands. Some recommendations for the management of common and grey alder stands are given.