CHEMICAL COMPOSITION OF THE ORGANIC MATTER IN FOREST SOILS

Abstract

The organic chemical composition of three different forest litter types (spruce, beech, ash) is characterized by comparing results obtained from (1) wet chemical degradations, (2) CPMAS 13C NMR spectros-copy, and (3) pyrolysis-field ionization mass spectrometry (Py-FIMS). From CPMAS 13C NMR spectros-copy, the litter layers consist of 17 to 23% alkyl-C, 52 to 56% O-alkyl-C, 15 to 23% aromatic carbon, and 5 to 10% carboxyl-C. The wet chemical methods account for 49 to 59% of the total organic carbon in the litter layers. More specifically, proteins and extractable lipids account for 30 to 40% of the alkyl-C. Polysaccharides and lignin side chains account for 74 to 78% of the O-alkyl-C, and lignin-derived phenols, determined by CuO-oxidation, account for 26 to 71% of the aromatic carbon. The identification of the organic litter constituents is substantiated qualitatively by Py-FIMS. All three methods give similar results for poly-saccharides, which make up 40 to 50% of the organic matter of litter. Furthermore, Py-FIMS indicates that part of the unknown alkyl-C is present in the form of bound, nonextractable fatty acids. © Williams & Wilkins 1988. All Rights Reserved.