Dry matter amounts and increment in 21- to 91-year-old common alder and grey alder and some practical implications

Growth data were collected from 32 stands of common alder (Alnus glutinosa (L.) Gaertn.) and 26 stands of grey alder (Alnus incana (L.) Moench) growing on forest land in Sweden. The stands ranged in latitude from 56 to 60°N and from 58 to 63°N, respectively. The mean ages of common and grey alder stands were 48 (range 21-91) and 40 years (range 21-66), respectively; the mean stand densities were 1114 (range 431-2994) and 1854 stems/ha (range 546-4031), respectively; and the mean diameters at breast height (outside bark) were 21 (range 12-28) and 17 cm (range 9-25). No statistically significant differences in site index were found among the four soil groups in common alder stands or among the three soil groups in grey alder stands. The mean total dry mass above stump level was 152 t·ha-1 with a range of 73-257 t·ha-1 for common alder stands and 139 t·ha-1 with a range of 82-218 t·ha-1 for grey alder stands. Mean annual mass increments outside bark for common and grey alders were 3.5 and 3.4 t·ha-1, respectively. Mean leaf area index was 2.85 for common alder stands and 3.04 for grey alder stands. Mean specific leaf area was 13.3 m2·kg-1 for common alder and 12.8 m2·kg-1 for grey alder. Some recommendations for management of common and grey alder stands are given.