Mineralogical and Micromorphological Modifications in Soil Affected By Slash Pile Burn.

Pile burning of logging slash is an important silvicultural practice, yet little is known about its effect on soil mineralogical properties. We investigated the effects of high-temperature fire on mineralogical and micromorphological soil properties of fine-loamy, mixed, frigid, Pachic Argiustolls. An experimental slash pile burn was conducted on soils ofManitouExperimentalForest in Colorado. Soil samples were collected from the depths of 0-5 and 5-10 cm prior to and after the burn. Temperature measurements were conducted continuously during the fire, with temperatures at soil surface reaching 500 ºC.

Mineralogical composition of the samples was analyzed with XRD using a Panalytical X’Pert Pro MPD diffraction system. While post-fire mineralogical composition of silt and clay fractions remained unchanged, poorly crystallized Mn minerals (pyrolusite and birnessite) were identified in sand fraction of post-fire soil. Thin sections were prepared and analyzed with petrographic microscope and scanning electron microscope in order to determine the changes in soil microstructure, fraction mophology and mineralogical composition caused by heating, as well identify the presence of Mn compounds.