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Wildfire severity and its environmental effects revealed by soil magnetic properties

Author(s): Neli Jordanova, Diana Jordanova, Vidal Barrón
Year Published: 2019

Strong wildfires pose significant damage to all soil compartments and lead to land degradation. The complex nature and properties of fire‐derived materials require multidisciplinary efforts for their reliable characterization. The main objective of our study was to evaluate the suitability of magnetic properties of fire‐affected soils as proxy parameters for wildfire severity and to relate magnetic signature of burnt soils to carbon and nitrogen contents as influenced by wildfires. We present mineral magnetic investigation of 22 sites with wildfire‐affected soils and 17 non‐burnt soils from nearby locations. We employed measurements of magnetic susceptibility and anhysteretic remanence in combination with scanning and transmission electron microscopy observations on magnetic particles from burnt soils and ashes. Bulk soil and vegetation ash analyses of total carbon and nitrogen, organic carbon and elemental content were carried out as well. We show that pyrogenic magnetic enhancement is restricted to the uppermost 0-2cm soil depth and can be used as a proxy for wildfire severity. Strong wildfires lead to the production of nm‐sized superparamagnetic magnetite and/or maghemite particles and smaller amount of single domain fraction. These strongly magnetic minerals have typical characteristics of high‐temperature combustion products with spherical shape and diameters between 0.1 to 2 microns. Fire‐affected soils show relative enrichment with phosphorous, manganese and heavy metals (Cu, Pb, Zn, Ni, Co, As) calculated with respect to soils from non‐burnt nearby localities. Our results demonstrate the potential of environmental magnetic methods as an additional tool for assessment of wildfire severity and the content of main soil nutrients.

Citation: Jordanova, Neli; Jordanova, Diana; Barrón, Vidal. 2019. Wildfire severity and its environmental effects revealed by soil magnetic properties. Land Degradation & Development 30-18:2226-2242. https://doi.org/10.1002/ldr.3411
Topic(s): Fire Effects, Ecological - First Order, Soil Heating, Ecological - Second Order, Soils, Fire Regime, Fire Intensity / Burn Severity
Ecosystem(s): None
Document Type: Book or Chapter or Journal Article
NRFSN number: 20587
FRAMES RCS number: 58280
Record updated: Jan 7, 2020