Getting to the root of the problem: litter decomposition and peat formation in lowland Neotropical peatlands

Litter decomposition is an important control on carbon accumulation in tropical peatlands. We investigated the contribution of different litter tissues from two peatland tree species (Raphia taedigera and Campnosperma panamensis) to peat formation in four lowland tropical peatlands in the Republic of Panama. Leaves, stems, and roots decomposed at different rates; with roots being the slowest to decompose among tissues. The position of litter in the peat profile strongly influenced the decomposition rate of all tissue types. Roots decomposed up to five times faster at the surface than at 50 cm depth. Molecular characterization of litter and peat profiles by tetramethylammonium-pyrolysis-gas chromatography-mass spectrometry (TMAH-Py-GC/MS) revealed that the peat is formed predominantly of decomposed roots and stems, as indicated by the high lignin, low methylated fatty acids and carbohydrate concentrations in these litter types. Taken together, these data demonstrate that roots play a fundamental role in the formation of lowland Neotropical peatlands.