Lipid fraction in forest litter: Early stages of decomposition

The lipid fractions of leaf or needle litters of ash, beech, birch, larch, oak, pine and spruce generally disappear more rapidly than non-lipid fractions, though the trend may be obscured by extensive fungal colonization as observed in 3-month old oak and ash samples. While the behaviour of most lipid subfractions is approximately species-independent, changes in concentration of material soluble in hot heptane but only sparingly soluble in cold ether are inversely related to bulk disappearance rate. The exceptional behaviour of this fraction in birch litter is perhaps a result of grazing by soil animals being the dominant removal process for birch leaves. Hot acid hydrolysis, presumably of ester linkages to lignin or polysaccharide, liberates a bound lipid fraction composed principally of fatty acids and accounting for up to 32% (in larch) of total lipid. Data for all species reveal rapid liberation and subsequent disappearance of free fatty acids by biochemical processes in the field.