Biomass equations for determining fractions of common and grey alders growing on abandoned farmland and some practical implications

摘要

A study was conducted in order to construct functions for above-ground biomass of fractions of young common alders (Alnus glutinosa (L.) Gaertn.) and grey alders (Alnus incana (L.) Moench. The constructed functions were designed to be used to predict the amount of biofuel produced from small areas. Biomass production was estimated in 10 stands of common alder and 15 stands of grey alder,, growing on abandoned farmland. The common alder stands were located in Sweden at latitudes ranging from 58 deg to 60 deg N, and their total age varied from 4 to 36 years. Grey alder stands were located at latitudes ranging from 60 deg 66 deg N, and their total age varied from 5 to 35 years. A modified `mean tree technique' was used to estimate biomass production, i.e. the tallest tree was chosen for samling. The mean total dry weight above the stump level for common alder stands was 39 tonnes ha~-1 with a range of 5 to 140 d.w. ha~-1 and 61 tonnes ha~-1 with a range of 3 to 140 tonnes d.w. ha~-1 for grey alder stands. The mean annual increment for common alder stands was 3.11 tonnes ha~-1 y~-1 (0.50-7.71) and 4.38 tonnes ha~-1 y~-1 (0.66-9.32) for grey alder stands. In addition to estimating comentional dry weights of trees and tree components, specific leaf area, total surface area and leaf area index (LAI), among other measures, were estimated. The mean LAI for common alder stands was 3.16 and 2.03 for grey alder stands. The specific leaf area per tree for common alder was 16.1 m~2 kg~-1 and 14.4 m~2 kg~-1 for grey alder. Practical implications of the findings are discussed.