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Daugaviete, M. 2011. Above-Ground Biomass in Young Grey Alder (Alnus incana [L.] Moench.) Stands.  Baltic Forestry 17 (1): 76-82

Presented is a method for estimating the amount of leafless naturally moist above-ground biomass in one-to-five-year-old untended naturally grey alder regenerating stands with the respective values calculated by using easy-to-measure stand parameters like the average height and the number of stems (root suckers, stool shoots, coppice, or saplings) per unit area. An equation is proposed for estimating the amount of biomass in one-to-five-year-old grey alder growth: biomass (M) is calculated as a function of the average stem height (HV) and the number of stems (N) per ha: M = 0.0536·HV2.2516·N,(R²= 0.905; P<0.05).
The biomass of untended young grey alder stands is calculated from the average stem height of HV =0.8-4.8 m in one-year-old and five-year-old stands, respectively, with the number of stems per 1 ha ranging from 10,000 to 100,000.
The calculations show that, with the average stem height in one-to-five-year-old grey alder stands increasing only by 0.1m, the amount of above-ground biomass increases by an average of 30%, provided the number of stems per ha is the same; in case the number of stems is by 10,000 larger, the biomass increase is by 40%.
The research shows that the amount of naturally moist biomass in one-to-five-year-old untended grey alder stands is uneven with the variations depending on stand age and stem dimensions.
The amount of biomass in untended grey alder stands depending on the stand density varies in a fairly wide range: from 0.9 t·ha⁻¹ to 7.7 t·ha⁻¹ ha in one-year-old stands; from 2.2 t ha⁻¹ to 23.6 t·ha⁻¹ in two-year-old stands; from 5.2 t·ha⁻¹ to 28.9 t·ha⁻¹ in three-year-old stands; from 7.3 t·ha⁻¹ to 57.4 t·ha⁻¹ four-year-old stands; from 15.2 t·ha⁻¹ to 64.4 t·ha⁻¹ per ha in five-year-old stands.

Key words: grey alder, biomass, average height, number of stems per ha, natural regeneration, coppice, saplings