Magnetic Properties of Plant Ashes and Their Influence on Magnetic Signatures of Fire in Soils

Fires are an integral part of many terrestrial ecosystems and have a strong impact on soil properties. While reports topsoil magnetic enhancement after fires vary widely, recent evidence suggests that plant ashes provide the most significant source burning. To investigate properties burnt material, samples individual species from Iceland Germany were cleaned combusted at various temperatures prior to rock geochemical characterization. Mass-normalized saturation magnetization values for residues increase with extent burning in nearly all samples. However, when normalized loss ignition, fewer than half ash charcoal display relative intact material. Thus, while mineral concentrations generally increase, changes total amount material much more variable. Elemental analyses Icelandic reveal both Fe strongly correlated Ti Al, indicating Fe-bearing phases originate inorganic such as atmospheric dust. Electron microscopy confirmed particulate matter remains surfaces cleaning. Plants textured leaf retain dust, these tend exhibit higher metal concentrations. Magnetic therefore result thermal transformation organic compounds matter, which become concentrated mass basis is combusted. These results indicate response will among sites regions function 1) fire intensity, 2) local composition dust particles surfaces, 3) vegetation type consequent differences morphologies.